The demand for a bidirectional dc–dc converter with a flexible dc bus is driven by the fast development of renewable energy system, transportation electrification, and microgrid. In order to accommodate different dc bus, two-stage ac–dc–dc architecture has been widely used, and the dc output regulation was handled by a rear-end dc–dc converter. If the galvanic isolation is not required, the four-switch buck-boost (FSBB) converter with quadrangle control is a good candidate because of the bidirectional noninverting output, step-up/down capability, and zero voltage switching. However, to achieve the minimum rms current and soft switching, the calculation of quadrangle control is complicated and often requires the resource-consuming loop-up tables, or additional high-frequency current detection circuits. Moreover, due to the unbalanced circuit topology, the common-mode (CM) noise is another concern. In this article, a symmetric three-level (3-L) buck–boost converter was first proposed to suppress the CM noise. To increase the power density and efficiency, a planar coupled inductor was designed for this 3-L buck–boost converter with a 30% winding loss reduction. And then, to realize a simple close-loop output control, a real-time simplified minimum rms current calculation for quadrangle modulation was found without look-up tables or ZCD circuits. Based on this simplified output control, a decoupled mid-points balance control for both input and output sides were also proposed. Finally, the simplified close-loop control, the decoupled active balance control, and the CM mode noise reduction were all verified by a 30 kHz 50 kW 3-L buck–boost converter. Compared with the typical FSBB converter, the proposed 3-L buck–boost converter has a up to 25 dB CM noise reduction from 150 kHz to 30 MHz. This article is accompanied by two videos demonstrating the effect of decoupled active balance control.

This article proposes a novel multi-agent framework that can link various forms of resources and power electronic systems into distributed energy resources (DER). The proposed multiagent architecture can also integrate DERs to a central controller for optimization and control to support the grid. To demonstrate the flexibility of this novel framework, the developed agent system is applied to a set of end-use systems. The agent framework is validated in hardware using controller-hardware-in-the-loop simulation platform.

The LCL filter has been widely used in the grid-tied inverter systems. However, the resonance of the LCL filter can reduce the system stability margin and the control performance. Moreover, the grid impedance variations can lead to the drift of the resonant frequency, which can further worsen the system robustness. Thus, it is important to know the actual resonant frequency of the LCL filter. In this letter, an adaptive extremum seeking control (AESC) based estimation scheme is proposed to estimate the resonant frequency of the LCL filter online. By injecting a high-frequency (HF) signal into the inverter output voltage, the AESC scheme can identify the extremum of the LCL filter amplitude response, i.e., resonant peak. The amplitude of injection signal is adaptive based on the inverter HF response, which can address the tradeoff between the dynamic response and inverter output current quality. Most importantly, compare to other method, the proposed scheme has very low computational complexity, which minimizes the burden to the normal inverter controller operation. Stability analysis is given in this letter, and experimental studies are conducted to validate the effectiveness of the proposed scheme.

This paper presents six groups of dynamic temperature-sensitive electrical parameters (TSEPs) for the medium-voltage silicon carbide (SiC) and silicon (Si) devices. The physical mechanisms of the temperature dependence of these parameters are analyzed with the difference between SiC and Si devices highlighted. A test platform is developed that enables implementation of the temperature relevant dynamic characterization. The investigated TSEPs are summarized in terms of their relationship with junction temperature, load current, DC voltage, and external gate resistance. The impact of the parasitic parameters on the evaluation results is analyzed. The comparison between 3.3 kV 5 A SiC MOSFETs and 3 kV 12 A Si IGBTs is conducted. The results verify that for the mediumvoltage SiC MOSFETs, the turn-off drain-source voltage switching rate, the turn-off gate current peak value, and the turnon gate current plateau achieve better thermal sensitivity, in comparison with the Si IGBTs. The turn-off and turn-on delay time exhibit better thermal linearity compared with other investigated TSEPs.

This article presents a systematic power stage design approach for a high-power density air-cooled inverter, which involves the utilization of emerging 1.7 kV silicon carbide (SiC) mosfet bare die engineering samples, heatsinks optimized with genetic algorithm, and built using three-dimensional printing technology and integrated power modules with a novel packaging structure. The developed air-cooled inverter assembly is mainly composed of the SiC mosfet phase leg modules with split high-side and low-side switch submodules, which are attached to two separate heatsinks for increased heat dissipation area and reduced thermal resistance. The heatsink is designed using a co-simulation environment with finite element analysis in COMSOL and genetic algorithm in MATLAB. The primary design procedure, including bare die device characterization, loss calculation, thermal evaluation, and power module development, is elaborated. The proposed design approach is verified and validated through experiments at each stage of development. The experimental results show that the inverter California Energy Commission efficiency is 98.4%, and a power density of 75 W/in3 is achieved with a sufficient junction temperature margin for semiconductor long-term reliability.

Heatsink design is critical for power density and reliability enhancement of power semiconductor modules. In this letter, an automated design and optimization methodology for air-cooled heatsinks are proposed based on genetic algorithm and finite element analysis. While the genetic algorithm generates a population of candidates with complex heatsink cross-section geometry in each iteration, finite element analysis is used to evaluate the fitness function of individual heatsink, i.e., junction temperature of semiconductor devices. With the rule of “survival of the fittest,” the proposed methodology eventually converges to an optimum heatsink design with the lowest device junction temperature. The optimized heatsink is fabricated through three-dimensional printing technology for thermal performance evaluation. Simulation and experimental evaluations have been conducted based on a 50-kW three-phase air-cooled inverter with the fabricated heatsinks. The comparative evaluation results show that the optimized heatsink is superior over a customized solution by 27% less in size and 6% lower in junction temperature.

This paper evaluates the temperature-dependent static and switching characteristics of SiC Trench mosfets in a low-inductance multiple-chip power module. First, a phase-leg power module package design with integrated decoupling capacitance is proposed and fabricated based on the P-cell/N-cell concept, and the module design including the substrate layout and packaging material selection are discussed. With the fabricated power module, the temperature-dependent static and switching characteristics of the SiC Trench mosfets are comprehensively investigated, and the key performance differences from the traditional SiC planar mosfets are discussed. Specifically, compared to the SiC mosfets with planar structure, the SiC Trench mosfets are observed to have a different temperature coefficient in term of the turn-off switching loss. Detailed analysis is provided as well to explain the experimental results.

Several wireless charging methods are under development or available as an aftermarket option in the light-duty automotive market. However, there are not a sufficient number of studies detailing the vehicle integration methods, particularly a complete vehicle integration with higher power levels. This paper presents the design, development, implementation, and vehicle integration of wireless power transfer (WPT) based electric vehicle charging systems for various test vehicles. Before having the standards effective, it is expected that WPT technology first will be integrated as an aftermarket retrofitting approach. Inclusion of this technology on production vehicles is contingent upon the release of the international standards. The power stages of the system are introduced with the design specifications and control systems, including the active front-end rectifier with power factor correction, high frequency power inverter, high frequency isolation transformer, coupling coils, vehicle side full-bridge rectifier and filter, and the vehicle battery. The operating principles of the control and communication systems are presented. Aftermarket conversion approaches, including the WPT on-board charger integration, WPT CHAdeMO integration, and WPT direct battery connection scenarios, are described. The experiments are carried out using the integrated vehicles and the results obtained to demonstrate the system performance including the stage-by-stage efficiencies.

Inclusion of power electronics allows increased controllability and stability in power systems. The simulation of such systems on a large-scale is challenging due to the presence of a large number of switches and nonlinear devices. This paper presents an advanced simulation algorithm to solve the aforementioned problem. The algorithm considers separation of differential algebraic equations (DAEs) on the basis of numerical stiffness and applies hybrid discretization algorithms to simulate the DAEs. The DAEs, in this paper, represent the nonlinear nonautonomous switched system dynamics of power systems. Stability analysis is performed on a general class of nonlinear nonautonomous switched systems to show the constraints under which the proposed algorithm is stable. To show the validity of the proposed algorithm, two case studies are considered: 1) single high-voltage direct current (HVdc) substation based on the modular multilevel converter (MMC); and 2) an example three-terminal MMC-HVdc system. Relaxation techniques are introduced to create a stable interface for the separated DAEs. The developed algorithms are also validated with PSCAD/EMTDC-detailed reference models.

Various noncontacting methods of plug-in electric vehicle charging are either under development or now deployed as aftermarket options in the light-duty automotive market. Wireless power transfer (WPT) is now the accepted term for wireless charging and is used synonymously for inductive power transfer and magnetic resonance coupling. WPT technology is in its infancy; standardization is lacking, especially on interoperability, center frequency selection, magnetic fringe field suppression, and the methods employed for power flow regulation. This paper proposes a new analysis concept for power flow in WPT in which the primary provides frequency selection and the tuned secondary, with its resemblance to a power transmission network having a reactive power voltage control, is analyzed as a transmission network. Analysis is supported with experimental data taken from Oak Ridge National Laboratory's WPT apparatus. This paper also provides an experimental evidence for frequency selection, fringe field assessment, and the need for low-latency communications in the feedback path.

Silicon carbide (SiC) power devices are expected to have an impact on power converter efficiency, weight, volume, and reliability. Currently, only SiC Schottky diodes are commercially available at relatively low current ratings. Oak Ridge National Laboratory has collaborated with Cree and Semikron to build a Si insulated-gate bipolar transistor-SiC Schottky diode hybrid 55-kW inverter by replacing the Si p-n diodes in Semikron's automotive inverter with Cree's made-to-order higher current SiC Schottky diodes. This paper presents the developed models of these diodes for circuit simulators, shows inverter test results, and compares the results with those of a similar all-Si inverter.

The electric grid is evolving into an electrical network composed of power electronic converters interconnected with renewable and energy storage technologies. This requires the adoption of more advanced control such as volt/var regulation, fast frequency control, and active power frequency response. This work presents a communication and control framework to support dynamically changing droop control segments that can be used for different optimization schemes. Results are presented to work in a controller hardware in the loop testbed.

With a vision to increase power density and standardize power electronics interface with the grid, this paper presents the design and validation of a SiC-based 75 kVA Intelligent Power Stage (IPS), comprising DC-DC and DC-AC power stages. The IPS is built on a modular 3D structure platform, where all three sides of the heat sink are utilized to achieve high power density (5.5 kW/L), including passives. The heat sink is custom-built and optimized to channel power from all three sides. Moreover, the intelligent features involve online non-invasive health monitoring of power stage components through a pseudo-optimized Digital Twin (DT) approach. DT also aids in identifying system failure modes, providing an extra layer of protection. Lastly, for grid-tie operation and interoperability, a hierarchical controller Smart Universal Power Electronics Regulator (SUPER) is proposed, which controls the DC-AC stage and monitors the health of IPS components through control and data communication channels.

This paper focuses on the development of a tool that includes an automated testbed with controls, protection, and communications integrated into a real-time system to provide a platform to generate data sets for failure modes and effects analysis. This tool establishes a value for automation of data generation for different scenarios and addresses the gap of nonexistent field data for different applications and use cases. The features of this tool can further be expanded to include multiple power electronics models, communication protocols, and scaled system architectures. This general framework was evaluated for a DC fast charger system use case to provide quantitative solution for resiliency.

This paper presents the application of a new design of a multiport, modular, medium-voltage power electronics hub (M3PE-HUB) in a microgrid setting. The M3PE-HUB system was modeled in a digital real-time simulator (DRTS) and integrated into the Banshee microgrid test system. This paper presents the preliminary DRTS simulation-based results of the M3PE-HUB system connected in a test microgrid system. Verification and validation of the M3PE-HUB architecture and controls in the test microgrid setting are the primary contributions of this work. The results of the operation during the islanding and resynchronization process indicate the feasibility of the proposed architecture in a microgrid setting. This paper also presents results for a system reconfiguration use case where the M3PE-HUB was used to reconfigure the system under a fault condition.

The goal of this work is to present an architecture, cost, and efficiency analysis tool of power systems, with emphasis on power electronics, for an off-grid, gigawatt-scale green hydrogen production for steel manufacturing, also known as green steel. The tool analyzes the main possible architectures based on commercially available components, such as wind generators, batteries, and electrolyzers. To reach gigawatt scale, different levels of aggregation are evaluated for DC and AC source-to-load coupling. The overall efficiency is estimated based on the efficiencies of each conversion stage, including transformers, AC/DC, DC/AC, and DC/DC converters, which are inputs to the tool. Similarly, the overall cost is estimated based on the cost per kilowatt of each system component, each of which is also an input. User defined input values, or default values may be used. The tool output is a list of the predefined architectures and its associated costs and efficiencies for decision support. A block diagram overview with the components of such architectures is also provided.

Electric vehicles adoption continues to grow. While charging infrastructure is anticipated to expand to meet the increased need, lack of EV charger system robustness is concerning and further compounds range anxiety. This paper discusses potential outage conditions associated with EV charging and presents new technology in development to improve EV charging resilience.

Planar magnetics design has been widely used in power electronics field because of the low profile, ease of manufacturability, and high power density. This paper first proposes a 3-level four-switch buck-boost (3L-FSBB) converter for the dc-dc applications where the zero common-mode (CM) voltage emissions, step-up and step-down are all required. With the consideration of power density, efficiency, and cost, a 15oz heavy copper coupled inductor for 3-level FSBB converter was designed and optimized with the low-cost commercial core and planar windings. According to the soft-switching quadrangle modulation for 3-L FSBB, the turns number and stacked core number are optimized first. And then, a two-board design is proposed to reduce the fringing effect and improve the thermal performance. Finally, a 75 kVA two-stage ac-dc-dc converter including a 3-level FSBB converter was built to verify the electrical design.

In this paper, a demand driven energy management (DDEM) technique is implemented on modular parallel input parallel output DC/DC auxiliary power supply (APS) structure. In this method, modules are brought in/out of the operation making them operate under high loading conditions, avoiding low efficiency under light load. Such a method finds its application in power conservative systems with variable load. Implementation of DDEM and the energy saved is shown using APS comprised of two 15W commercially off-the-shelf DC-DC modules, with 100–1000 VDC input and 24 V output voltage. Along with the DDEM, the lifetime of the power stage devices is controlled minimizing their junction temperature swing through control of cooling system. This control method uses digital twin as interface to virtualize the power devices loading operation/ health condition. Accordingly, no extra sensor or closed loop control required to measure the junction temperature of the devices or feedback the losses to the cooling flow.

The paper presents a novel and futuristic architecture for a megawatt charging system (MCS) capable of charging light, medium, and heavy-duty vehicles. The station architecture consists of multiport systems with each multiport interfacing the grid, EV, PV, and energy storage system through an intermediate DC bus. The station being a “system of systems” requires a complex software layer with intelligence, control, and communication for effective coordination and utilization of the power electronic interfaces and the assets. The paper elaborates on the station architecture and the associated software layer used for control and coordination. Additionally, the paper provides an approach to utilize hardware-in-the-loop (HIL) capabilities to validate such architectures.

The demand for grid-interface converter with flexible dc bus is driven by the fast development of energy storage system (ESS), electric vehicle (EV) charging system, and versatile residential load. This paper first proposes a two-stage intelligent power stage (IPS) unit for future grid-interface applications. To achieve zero common-mode (CM) voltage emissions, step-up and step-down voltage gain, a 3-level four-switch buck-boost (3-L FSBB) dc-dc converter is adopted with fully zero voltage switching (ZVS). In one IPS unit, an advanced fiberoptic communication with sub-nanosecond synchronization is developed for different enhanced gate drivers. Moreover, an enhanced gate driver integrated current and voltage sensors is designed for monitoring and diagnostics. To achieve a whole low-profile design, three 12 oz heavy copper planar ac inductors are designed and implemented. Finally, a 75 kVA IPS unit was built to verify both the thermal and electrical design.

This paper presents a medium voltage energy hub based on a modular design of a multilevel cascaded H bridge (CHB)-dual active bridge (DAB) converter. The energy hub composed of the two CHB-DAB modules with a back-to-back topology can be utilized as a grid interconnection component between distribution feeders. The energy hub can provide multiple simultaneous grid services such as voltage regulation, power factor correction, as well as active power flow control between the connected feeders, contributing to grid flexibility, efficiency, reliability, and resilience. Circuit structure and control schemes for the energy hub including both local controllers for each converter and outer loop controllers are proposed to enable simultaneous grid services with coordination to prevent the overloading of the hub. To validate the performance of the hub, the hub system is interconnected between two IEEE 4-bus feeders and provides voltage regulation for both feeders, while controlling active power flow between them. The system and the feeders are implemented in Real-Time Digital Simulator (RTDS) for real-time simulation verification.

In this paper a new concept of multiport, modular, medium-voltage, power electronics hub (M3PE-HUB) is introduced for the future power grid. The goal for this project is to design, develop, and demonstrate foundational technologies and capabilities for multiport power electronics energy hubs that can serve as intelligent devices to coordinate and control several different sources and loads. This paper presents the architecture of the controller, the central controls, and their verification.

A SiC-based intelligent power stage (IPS) with zero-voltage-ride-through (ZVRT) and device prognosis & diagnosis (P&D) capability is proposed for power electronics grid interface systems. Compared to other grid-tied power converters, the proposed IPS embeds online health monitoring of SiC device into its intelligent and integrated gate drivers (i2GDs). In addition, a low-latency hardware-based approach with fast-response is developed to suppress large inrush current during ZVRT transients. The fiber-optic based robust communication architecture to transfer SiC device health status signals, P&D information, PWM signals, as well as fault signals between IPS local controller and i2GDs are illustrated. A 50kW IPS prototype is built and tested in the laboratory. Simulation and experimental results are presented to validate the advanced features of proposed IPS.

This work proposes a three-stage converter topology with a medium frequency isolation transformer for direct integration of energy storage systems into medium voltage distribution grids. The distributed architecture of the topology, using standard AC/DC converters, has been developed with the aim of plug-and-play capability and voltage and power scalability. The medium frequency transformer facilitates improved power density, while its 20:1 voltage translation capability enables the use of limited voltage level (500 Vdc) of the commercially available batteries. This paper presents the topology structure and details how it can be scaled to reach the full range of the distribution grid voltages and the required power levels. A transformer design for 500 Hz rated frequency is discussed. The control scheme of the converter equipped with voltage support, frequency support, and black start capabilities is also presented. Control hardware-in-the-loop results using OPAL-RT, with converter switching models connected to a weak IEEE-4 node test feeder modified for the aforementioned grid services, are provided to show the topology feasibility.

Power electronic (PE) systems are increasingly being integrated into distribution and sub-distribution networks in support of distributed energy resource integration (DERs), electric vehicle (EV) charging (particularly in the case of fast charging infrastructure), and improvement in power quality for high performance computing and/or servers farms. This provides an opportunity to research and develop integrated PE systems that can function as single systems thereby bringing additional functionality and benefits to the overall system. The goal of this paper is to demonstrate foundational technologies and capabilities for a multiport power electronics energy hub that can intelligently coordinate and control integrated sources and loads. The focus for this digest is on a commercial building use case which is demonstrated in hardware.

The startup of systems composed of power electronic systems is becoming more complex. As the systems grow, standard pre-configuration sequencing methods will struggle. This work proposes a linear programming optimization method to couple power electronic systems in a series of startup commands. This formulation is demonstrated in a real-time implementation on hardware.

Extreme fast charging of electric vehicles technologies is coming. Heavy duty electric vehicles (HD-EVs) are in development and are expected to have multipliers bigger in battery capacity compared to the light duty counterparts. To meet short charging times, MW charging will be necessary. This paper presents a MW scale extreme DC fast charger with a communication and control architecture for HD-EVs. The system is validated in a controller hardware in the loop platform.

With the growing deployment of distributed generation, or power electronic interfaced renewable energy and storage technologies, the nature and behavior of the grid is changing. Synchronous machine-driven asset contributions to the generation mix are shrinking, leading to concerns regarding grid stability. Furthermore, the scale of smaller distributed PE resources needed for managing the electrical network could dwarf the existing system leading to more complex optimization problems and communication interconnections. This paper introduces the concept of a hierarchal system of controllers that spans the grid edge or the customer end to distribution scale substations or solid-state power substation (SSPS). This concept focuses on minimizing the number of interfaces and optimization considerations in the grid by clustering resources into nodes and hubs. The work validates the concept in a controller hardware-in-the-loop (cHIL) platform.

This paper presents a plug-and-play power electronic system for integration of multiple energy storage system technologies. The system uses a communication and control architecture with individual developed modules to support scaling to larger systems for the electric grid. An optimization framework is also presented to demonstrate the functionality of the system. This system is shown to work in hardware with a constructed testbed to demonstrate different use cases and systems. Results are presented for a full efficiency cycle test.

As DC fast charging electric vehicle (EV) infrastructure continues to expand, potential challenges loom. One issue is the potential for EV charger outages due to electrical grid voltage transients. Today, EV chargers are expected to disconnect under a severe voltage sag (below 70%) which reduces electric vehicle charging infrastructure resilience. This work proposes a droop-control solution to ride-through voltage sags and maintain operation. The control solution is presented in a controller hardware in the loop platform.

Solid-State DC Circuit Breaker (SSCB) have been proposed for faster breaking response as compared to traditional electromechanical circuit breakers. It offers the potential for integration of functionality and reduction of footprint of the system. This is achieved by operating the devices in active region to limit the start-up current through capacitive loads. This paper proposes a RC assisted close-loop Active Gate Control (AGC) to soft-start capacitive loads. The proposed solution aims to achieve a more generalized solution which is independent of device type and characteristics while offering utilization of off-the-shelf gate drivers. The negative feedback based close-loop AGC offers the advantage of compensating device's non-linearities and dependencies. The proposed solution also gives the flexibility of either using RC circuit to soft turn-off under load and bypass it after start-up process for faster response under low impedance fault. This paper discusses the dynamics of the devices and close-loop design of the system. To validate the proposed solution, simulation and experimental results are given on a 900 V 15 kW prototype.

This paper proposes and demonstrates a real-time condition monitoring method using gate driver integrated sensing circuits and sensor fusion algorithms. Power device on-state voltage $(\mathbf{V}_{DSon})$ measurement and junction temperature $(\mathbf{T}_{j})$ sensing circuits with high noise immunity are built and integrated into an adaptive gate driver circuit for power modules. Considering the inherently noisy measurement environment of power converters, $\mathbf{V}_{DSon}$ together with several other measurements are fused together to provide accurate descriptions of the stress and degradation of each power device. Furthermore, the gate driver circuit can actively control the turn-on gate voltage $(\mathbf{V}_{GSon})$ for each device based on the stress and degradation state. The proposed sensing circuits and power device condition assessment algorithms are implemented in a 75 KVA grid-tied power converter. This paper focuses on the sensing circuits hardware designs and testing in grid-tied power converter prototype and device stress index generation. More comprehensive results on the device state of health index generation will be presented in future work.

As power electronic systems (PESs) grow increasingly complex, integrating and testing these systems in the development stages is becoming more crucial and more challenging. New modes and resource integration strategies are in development and must be tested before pilot demonstrations and mass production. This paper proposes a framework for testing of PES technologies including early validation with integration of simulated resources. The framework is demonstrated to work in two example configurations as proof of principle.

This paper proposes an optimization model for the optimal configuration of an grid-connected electric vehicle (EV) extreme fast charging station considering integration of photovoltaic (PV) and energy storage. The proposed model minimizes the annualized net cost (i.e., maximizes the annualized net profit) of the extreme fast charging station, including investment and maintenance cost of charging ports, PV and energy storage, net cost of purchasing energy from utility and selling energy to EV customers, degradation cost of energy storage and demand charge. The decision variables are number of charging ports, capacity of invested PV and the power and energy ratings of invested energy storage. The Erlang-loss system is adopted to model the EV mobility. Results of numerical simulations indicate that investment of PV and energy storage could increase the annualized profit of the extreme fast charging station. In addition, the impacts of various parameters on the optimal solution are investigated by sensitivity analysis.

DC stacked topologies have gained popularity for interfacing individual photovoltaic panels to a high-voltage DC bus. A similar approach can be used to interface individual battery packs to the same DC bus, which allows active balancing of battery substrings and the use of lower voltage switches. Any imbalance in battery current, however, can cause the converter output voltages to diverge. This paper describes the source of voltage divergence and demonstrates a solution that allows seamless stacking of multiple battery packs to be interfaced to a high voltage DC bus. To prevent the voltage divergence phenomenon and allow asymmetrical battery charging for efficient battery state of charge management, the PI-based decentralized voltage control enabling both capacitor voltage sharing and asymmetrical capacitor voltage control is proposed. The effectiveness of the decentralized voltage control strategy is demonstrated through controller hardware-in-the-loop test results.

This paper proposes a computationally efficient mixed integer linear programming (MILP) model for the coordinated optimization of solid-state power substations (SSPSs) in a feeder considering the full unbalanced three-phase structure of the distribution grid and its characteristics. The proposed model determines the optimal real and reactive power of each SSPS at the point of common coupling (PCC) that minimizes the operating cost and maximizes the system performance, e.g., voltage regulation and phase balancing. To improve the computational efficiency, an inscribed octagon is introduced to approximate the quadratic capacity constraints of components. Numerical simulation results show the effectiveness of the proposed model and significant improvements in voltage profiles and power imbalance between phases.

The growth in load and generation sources at the edge of the grid is driving the innovation in power electronic (PE) grid interfaces at the consumer end to improve the grid resiliency, reliability, security, and cost of the future infrastructure. Novel PE technologies are key enablers for the future grid infrastructure to handle the issues that arise because of the projected growth. This paper introduces a novel fundamental building block (FBB) architecture with plug-and play features. An example framework that enables co-ordination of multiple FBBs hierarchically to provide various grid functions is also presented. The FBBs are designed to be equipped with advanced features like online health monitoring, embedded intelligence, and decision-making capability for enhancing the metrics of consumer end plug and play interfaces. The paper elaborates on the proposed architecture and the developed framework i.e., the controls, communication, protection, and the corresponding timing requirements for the building blocks. The architecture and the framework have been validated through simulations and the communication framework has been validated with a control hardware in the loop platform.

Low-cost, grid-connectable energy storage technologies represent a significant challenge for the electric grid of the future. Energy storage technologies are in rapid development with targets to reduce the storage medium cost. However, a significant cost to deployment also comes in the integration. This paper presents the development of a plug-and-play system for supporting secondary use multiple battery systems into a single grid connectable unit. Results of the system design are demonstrated in a controller hardware in the loop (CHIL) platform. Simulations of two energy storage systems operating in parallel and dispatched optimally are presented.

High integration rates of new loads and distributed generation at the edge of the grid are posing new challenges. However, existing smart power electronic systems are not designed to coordinate and maximize grid support or provide multiple grid services simultaneously. This work presents the application of a solid-state power substation (SSPS) to residential systems to increase this coordination and reduce future challenges. The proposed residential SSPS is validated in simulation including power electronic converter models, feeder models, and optimization.

Power electronic systems are becoming a staple building block for electric grid networks. However, these systems have been largely designed to grid integrate in ad hoc configurations with little or no coordination of control. This work proposes a central controller and power electronic system hardware and software design for a residential system (photovoltaic, energy storage and residential building). This system supports auto-integration, plug and play capabilities, and optimal energy management to meet different use cases. Modelling and multi-day testing of the system have been conducted in a controller hardware-in-the-loop (C-HIL) testbed. Multiple use cases and pricing options have been considered as part of the simulation and testing. Results are presented of these systems as a proof of principle.

The resonant frequency of the LCL filter can drift away from its nominal value due to the circuit components parameters uncertainty and the grid-side impedance, which will further deteriorate the robustness of the system and damping performance. Conventional online resonant frequency estimation schemes, such as discrete Fourier transformation and recursive prediction error, require a significant amount of computational power to implement, which may even need to reduce the sampling and control frequency of the inverter controller. In this work, an extremum seeking control based resonant frequency estimation scheme is proposed, which can provide an accurate estimate of the resonant frequency with notably reduced execution time. Simulations, hardware-in-the-loop (HIL) tests, and experimental tests on a single-phase grid-tied inverter are conducted to validate the effectiveness of the proposed scheme.

This paper proposes and demonstrates a liquid metal-based cooling system for power converters with an inductor integrated magnetohydrodynamic (MHD) pump. The inductor in this case not only functions as the pump for liquid metal but also can be an essential part of typical power converters such as the output inductor of a buck converter. Two prototypes of liquid metal-based cooling systems were designed and built. The first prototype is an MHD pump with an external current source and permanent magnets and to evaluate the effectiveness and power consumption of liquid metal based cooling. The second prototype for the first time integrates the MHD pump into an inductor, which eliminates the need for an external power supply and permanent magnets. Since the inductor is part of the power converter to be cooled, the flow rate can be self-adjusted with the load condition. Simulation and experimental results validate the concept of the inductor integrated liquid metal pump and demonstrate the advantage of the liquid metal cooling system over non-metallic fluid-based liquid cooling systems in terms of power density, cooling efficiency, power consumption, reduction of rotatory components, and lowered acoustic noise.

Like many areas in research and development, power electronic and distributed energy resource research and development slowed during the COVID pandemic. While the presence of the virus has reduced and workers are returning to shared offices, uncertainty of potential future challenges are still present. This work proposes a development and testing network that provides researchers the ability to operate remotely and coordinate control and debug activities for power electronic systems. This development and testing network has been demonstrated in both controller hardware-in-the-loop (C-HIL) and hardware testing.

This paper presents the communication, control, and architecture, for a low voltage (nominal 480V) hybrid AC/DC microgrid for supporting small commercial buildings with critical data center loads. The proposed system is based on a dc-power electronic hub (PEH) that seamlessly integrates renewable energy resources, energy storage, and back-up generation to support commercial building economical energy management and reliability. This PEH concept provides a parallelization of critical power to the commercial and industrial buildings leading to increased efficiency and reliability compared to traditional uninterruptable power supplies. The demonstration of the proposed PEH architecture and controls is conducted through a controller hardware in the loop validation.

Continental level power system interconnections using a High Voltage direct current (HVDC) transmission lines have been considered to bring economic benefits such as interregional power exchange. This paper describes the modeling process and studies the technical benefits of having multiple HVDC lines, including a grid of HVDC lines (macrogrid) configuration, connecting the North American Eastern and Western electric power interconnections. The models developed provide steady state and stability analysis for multiple HVDC overlay topologies and provide technical benefit analysis in terms of frequency response and congestions management. The paper also provides a comparison of different HVDC topologies performance and their grid support in case of major disturbances.

Silicon carbide (SiC) power devices operate at high switching frequencies with high voltages and good stabilities owing to their advantages in excellent breakdown field strength, heat dissipation characteristics, and electron saturation velocity, and so on. Therefore, SiC-based systems can achieve a high power density compared to conventional Si-based systems. However, high dv/dt and di/dt accompanied with high-speed switching operations can cause EMI noise issues. Traditional gate drivers cannot actively control such EMI noise problems. This digest proposes an integrated active gate driver (AGD) to solve the noise issues. The proposed AGD controls the switching speed through controllable AGD voltages in real-time according to the system feedbacks such as the DC-link voltage, output current, and device temperature. The proposed AGD enables switching devices to control the switching speed accurately under various system operational conditions. Simulation and experimental results are presented to verify the proposed method.

This paper proposes an optimization model for the optimal sizing of photovoltaic (PV) and energy storage in an electric vehicle extreme fast charging station considering the coordinated charging strategy of the electric vehicles. The proposed model minimizes the annualized cost of the extreme fast charging station, including investment and maintenance cost of PV and energy storage, cost of purchasing energy from utility and demand charge. The decision variables are capacity of invested PV and the power and energy ratings of invested energy storage. To further reduce the annualized cost of the extreme fast charging station, the charging strategy of electric vehicles are integrated into the optimization model and coordinated with the power output of PV and charging/discharging of energy storage. Results of numerical simulations indicate that investment of PV and energy storage could help reduce the annualized cost of the extreme fast charging station significantly. Meanwhile, the impacts of various parameters on the optimal solution are investigated by sensitivity analysis.

In this paper, the concept of a framework based on an agent-based interface for power stages in a power electronic system is presented. The presented concept or agent system is able to consider any number of different types of sources, types of converters, communication protocols, embedded decision making to support transactive, and hierarchy for large system integration. The concept is presented through several examples including the implementation on an actual physical system and demonstration of transactive type controls.

With increase in distributed energy resources (DERs) and smart loads, each energy resource and load need a separate power conversion system leading to complex coordination and interaction, reduced energy conversion efficiency, coordinating compliance to grid standards (IEEE 1547) from multiple sources, reduced security. Also, multiple vendors with legacy system designs and proprietary communications interfaces result in redundancy and increase in cost of power electronics systems. This paper presents an energy router concept for buildings applications which provides autonomous power flow between sources and loads with a novel agent-based software interface.

In this paper, we propose a novel resilient microgrid scheduling model considering the multi-level load priorities. The resiliency of the microgrid is guaranteed by quickly adjusting the output of committed local resources and shedding the loads with low priorities when the power supply from the main grid is interrupted. Considering the uncertainty of renewable energy resources and loads as well as exchanged power at PCC, the probability of successful islanding (PSI) is used to quantity the resiliency of electricity supply for various loads with different priorities. Then, the multi-level priorities are enforced through chance constrains. Results of numerical simulation validate the proposed resilient scheduling model. In addition, the impacts of resiliency requirement of loads with high priority on the resiliency of loads with low priority are analyzed as well.

In most of the research, a conventional one degree-of-freedom type proportional-integral controller (1DOF-PI) is used for the regulation of the dc bus voltage in an Active Front-End Converter (AFEC). This paper proposes a two degree-of-freedom type proportional-integral controller (2DOF-PI) for the regulation of dc bus voltage in an AFEC. Such a controller eliminates the left-half plane (LHP) zero in the command-to-output transfer function for dc bus voltage regulation that is inherent to the conventional 1DOF-PI for this application. The dynamic model of an AFEC in the synchronous reference frame (SRF) is presented. An inner current control and outer dc voltage control loop is built for controlling the AFEC. Vector-control scheme is employed to achieve decoupled control of direct-axis and quadrature-axis currents. The outer dc voltage control loop is designed with a 2DOF-PI to complete the control system. Transfer function (TF) of the controller is derived based on the presented model and used to calculate the controller gains. Transient and steady state performance of the designed controllers are investigated in MATLAB/Simulink and results presented.

This paper presents five dynamic temperature-sensitive electrical parameters (TSEPs) for the medium-voltage silicon carbide (SiC) and silicon (Si) devices. The theoretical temperature dependence of these parameters is analyzed. A test platform that enables to implement the temperature relevant dynamic characterization is developed. The tested TSEPs are summarized in terms of their relationship with junction temperature, drain/collector current, DC voltage, and external gate resistance. The comparison between the 3 kV 12 A Si IGBT and 3.3 kV 5 A SiC MOSFET with the identical TO-263 package is conducted. The results verify that the turn-off drain-source voltage switching rate achieves better thermal sensitivity for medium-voltage low-current SiC MOSFETs compared with Si IGBTs. Both the turn-on and turn-off delay time exhibit better thermal linearity for the two devices. The turn-off delay time further achieves five times better thermal sensitivity than the turn-on delay time for investigated medium-voltage SiC MOSFETs.

The following topics are dealt with: security of data; power engineering computing; invertors; photovoltaic power systems; power grids; smart power grids; power distribution control; computer network security; power system security; power generation control.

Power electronic (PE) systems are increasingly being integrated into the electric grid in a distributed fashion. As the number of installations increases, the challenge of integration of these systems into the grid is also growing. Advanced control features of these systems are often overlooked or neglected due to the complex nature and novelty of these systems. This is also complicated from the vendor point of view as different converter topology integration is usually composed of single system designs with tight coupling and configurations. The presented work discusses a novel architecture for the integration of PE systems with other sources and loads to create a coordinated controllable resource for the grid. The presented work also describes a system level controller to coordinate these systems. ¹Testing results on a hardware in the loop (HIL) platform are provided to show the validity of the proposed architecture and framework.

This paper summarizes the fault mechanisms specifically for the overvoltage protection schemes in power electronic converters and the resulted power electronics enabled systems. A flexible and secure evaluation platform for overvoltage protection, has also been presented based on this conceptual mechanism. The proposed platform aims at testing the protection performance of distinctive overvoltage protection schemes. It would be applied to verify the effectiveness, identify potential strengths and weaknesses, and obtain the most critical protection response time to provide sufficient engineering insights for the designer. The operation principle and detailed design guideline have been presented first. The comprehensive component stress has been analyzed. An intensive set of LTSpice simulations have been conducted to show the validity of the proposed assessment approach.

Many energy storage systems that use technologies such as batteries are composed of power electronics conditioning systems and battery management systems. These are often produced by multiple manufacturers and require hardware and software integration for full grid functionality. This paper proposes an agent-based framework to support the development of an energy storage system with standardized communications. This framework can be utilized with different power conversion systems with an appropriate hardware interface.

The next generation of utility-scale energy storage will be composed of modular systems and autoconfiguring software. This is key to incorporating battery management systems (BMS) and power electronic converters (PEC) from multiple manufacturers into a cohesive single system. In this paper, an agent-based architecture which supports the integration of numerous BMSs and PECs is proposed. This architecture supports optimization and control of the entire system and can be used in many different energy storage technologies.

Secondary-use energy storage systems (ESS) are a potential low-cost energy storage system for the electric grid. These systems propose a low-cost solution to the challenge, what to do with electric vehicle batteries once EV end-of-life has been reached. However, the development of an ESS is complex by nature. Typically, the bidirectional power electronics conversion (PEC) system has hardware which includes power stages, auxiliary circuits, protection circuits, and the control interfaces all embedded and integrated as a system. This leads to interoperability challenges and vendor dependencies that increase balance of system costs. This paper proposes a modular approach of software and hardware interfaces to reduce the costs of an ESS.

Power electronics devices are emerging at residential houses, including electric vehicles, energy storage systems, solar photovoltaic systems, and variable-speed air conditioners. Little work has been done on scalable and end-to-end architectures for integrating and engaging large number of residential behind-the-meter assets to provide grid services. In this paper, a framework for integration of a demand management system, home energy management system, and residential smart inverters is presented. Full measured results of inverter response to control signals is also presented.

This paper presents a fault ride-through control strategy for grid-tied virtual synchronous generator (VSG) under two main grid fault conditions, grid voltage sag fault and unintentional grid outage fault. Considering the overcurrent issue of VSG during the grid voltage sag fault, mechanism on overcurrent issue and the relationship among power angle, voltage amplitude, active power and reactive power are analyzed. Based on the analysis, a control strategy based on direct power angle and voltage amplitude control is proposed. Compared to the common control strategy based on additional inner current loop, the proposed VSG requires no add extra voltage or current sensors. For the grid outage fault, detailed analysis on the relationship among power angle, active power and frequency has been conducted, and it is found that the power angle is related to the output active power when the converter operates on grid-tied condition; under unintentional islanding conditions, the power angle is related to the voltage frequency. Based on the found, a detection method based on small frequency disturbance is proposed. Simulation studies on a prototype VSG system are presented to demonstrate the validity of the proposed control strategy.

Grid modernization efforts are leading to increased penetration of power electronics in the existing alternating current (ac) bulk power systems (BPS). Some examples of power electronics based applications that are being developed in BPS include high-voltage direct current (HVdc) systems, renewable generation systems, energy storage systems, and others. One of the requirements to succeed in the goals of grid modernization (like increased efficiency and reliability) is to setup a platform that can evaluate basic building blocks of such systems. For example, the basic building block of a modular multilevel converter (MMC)-based HVdc system is a submodule (SM). The evaluation platform will provide means to innovate new SM circuit architectures, new semiconductor devices in the SM, new gate-drivers, new controllers, and others. The flexible intelligent real-time dc-ac grid emulator (FIRE) platform incorporates the evaluation capability to evaluate the basic building blocks. The FIRE platform incorporates this evaluation capability through the power electronic hardware-in-the-loop (PE-HIL) concept. The PE-HIL for MMC-HVdc system can evaluate SMs in the MMC. In this paper, the design of amplifier required to perform PE-HIL simulation is presented. Experimental results of the amplifier and the simulation results of the PE-HIL concept utilizing the amplifier are presented.

In this paper, a comprehensive voltage control loop design for a dual active bridge (DAB)DC-DC converter is proposed using the sliding mode control (SMC), where the coefficients are formed to ensure both small signal and large signal stability of the system. The major objectives of the proposed SMC are to enhance the converter dynamics and attain a tight output voltage regulation under fast load fluctuations or during start-up. In addition, dynamic performance of the system is examined considering the steady state error and overshoot. The proposed control method is capable of achieving soft-switching operation by determining the effective duty phase displacement range. To verify the proposed method, a hardware prototype of a DAB converter is developed and evaluated, and the effectiveness of the loop design is validated by the experiment. It is observed that overshoot is eliminated in the start-up test and the fast settling time is achieved.

Middle-point inductance Lmiddle can be introduced in power module designs with P-cell/N-cell concept. In this paper, the effect of middle-point inductance on switching transients is analyzed first using frequency domain analysis. Then a dedicated multiple-chip power module is fabricated with the capability of varying Lmiddle. Extensive switching tests are conducted to evaluate the device's switching performance at different values of Lmiddle. Experiment result shows that the active MOSFET's turn-on loss will decrease at higher values of Lmiddle while its turn-off loss will increase. Detailed analysis of this loss variation is presented. In addition to switching loss variation, it is also observed that different voltage stresses are imposed on the active switch and anti-parallel diode. Specifically, in the case of lower MOSFET's turn-off, the maximum voltage of lower MOSFET increases as Lmiddle goes up; however, the peak voltage of anti-parallel diode decreases significantly. The analysis and experiment results will provide design guidelines for multiple-chip power module package design with P-cell/N-cell concept.

Inductive power transfer has been proposed as a solution to power future automated and electrified highways. In this study, an interoperable wireless charging system is sized so that a light and a heavy-duty vehicle can travel at or near charge-sustaining mode at high speeds using an optimization approach. The conflicting objectives of minimizing the power ratings and the number of inverters, coupler materials, and overall system coverages result in a Pareto Front that is presented in this paper. It is found that a system using short transmitting couplers can ensure high efficiency power transfers to light-duty vehicles (LDVs) and still maintain charge-sustaining operation of heavy-duty vehicles (HDVs). The findings are contextualized by a brief discussion of other aspects relating to the implementation of this technology on roadways such as the impact of the cost of time and travel speeds.

The traditional heatsink design technologies for forced air-cooling and power semiconductors with low junction temperatures have constrained the converters to be designed with massive heatsinks. The low power losses of WBG device technology and higher junction temperature operation over a wide operating range of power have not been fully utilized with liquid-cooled systems. The other major limitation has also been the traditional power module packaging “stack” approach with baseplate. This paper presents a novel power stage design which involves 1.7 kV silicon carbide (SiC) MOSFETs, a heatsink design with Genetic Algorithm (GA) and built using 3D printing technology, and a novel integrated modular power module for high power density. The air-cooled module assembly has a SiC MOSFET phase leg module with split high-side and low-side switches and a gate driver with cross-talk and short circuit protection functions. The heatsink design was modeled using a co-simulation environment with finite element analysis software and GA in MATLAB and COMSOL. The proposed concepts were verified and validated through experiments at each stage of development. The power stage was evaluated at 800V, 900 V, and 1kV for 20 kHz switching frequency and 50-kW load. The experimental results show that the CEC efficiency is 98.4 %. In addition to the efficiency, a power density of 75 W/in3 was also achieved.

A modular and scalable SiC MOSFET based universal power electronics regulator (UPER) allows coordinated integration of energy resources and loads, elimination of extra power conversion stages, and allowance of more sources or loads added with a simple plug and play feature. A comprehensive investigation has been conducted in term of the typical distributed generations and loads employed in buildings, in order to outline a detailed specification for UPER. Thus, a common DC bus voltage of 500 V and power rating of 3 kW are dedicatedly selected. The UPER hardware design and implementation are completely illustrated, including the static and dynamic characterization of the employed SiC MOSFET. The dedicated universal power cell and Plug-and-Play gate driver performs reliable continuous operation even exposed to an extreme fast switching speed (> 100 V/ns). The continuous operation of buck mode verified the UPER hardware development at 50 kHz with an overall efficiency of 98.19%. A new voltage polarity reversal phenomenon was also discovered in the verification of the isolated DAB stage with planar transformers.

This paper deals with the development of a low-inductance multiple-chip power module with state-of-art 1200 V SiC Trench MOSFETs for high-frequency application. Specifically, a phase-leg power module package with integrated decoupling capacitance is fabricated based on P-cell/N-cell concept, and the packaging design is discussed in detail. Dedicated double pulse test is built, and a gate driver with cross-talk suppression function is designed to support the fast switching speed operation of SiC Trench MOSFETs. The parasitic inductance and current density distribution of the power module are simulated and extracted for the purpose of voltage spike limiting. The temperature dependent static and switching characteristics of the developed module are evaluated as well, and the key differences from traditional SiC double-diffused MOS (DMOS) are identified and discussed. Based on the turn-off switching characterization results, a lumped equivalent power-loop parasitic inductance of ~6 nH is achieved for the designed power module.

Wireless power transfer is going to play a major role in transportation electrification due the convenience, flexibility, safety, and high-efficiency. Achieving high power levels is important in order to reduce the charge times and provide more convenience to electric vehicle (EV) owners while keeping the efficiency high and electric and electromagnetic field emissions lower than the limits set by the international guidelines. This study presents a 20-kW wireless charging system designed for a Toyota RAV4 electric vehicle for stationary charging with a dc-to-dc (high-frequency inverter input to the vehicle battery terminals) efficiency exceeding 95% over four power conversion stages. Additionally, the modeling, analysis, and sensitivity of the wireless charging system are presented for series-series resonant tuning configuration.

Autonomous and electrified mobility are two key developments expected in the next decade to improve the efficiency and reduce carbon footprint of transportation. As electric vehicles (EVs) increase on the roads, one of the issues that needs to be addressed is range anxiety. To mitigate this problem and for seamless integration of EVs, dynamic wireless charging is an attractive solution. In this paper, a few case studies are considered in a smart autonomous highway to understand the impact of dynamic wireless charging on grid dynamics. The studies show that the grid voltages vary significantly due to the dynamic wireless power transfers (DWPTs), if connected to the existing grid. The variations in the grid voltage can reduce power transfers, increase grid instability, and cause inadvertent protection triggers. The inadvertent protection triggers can reduce the reliability of the connected grid. These problems highlight the need for modern grid infrastructure to support DWPT systems.

This paper presents the sensitivity analysis of primary-side LCC tuned and secondary-side series tuned wireless charging system with experimental validation. The primary and secondary coils have been modeled as a loosely coupled transformer to obtain a circuit model which can be analyzed for parametric sensitivity. Furthermore, sensitivity to variation in coupling coefficient and load are presented. To prove the effectiveness of the theoretical analyses, a test setup was built and tested up to 10kW, demonstrating the operation of the primary-side LCC and secondary-side series wireless power transfer system. The circuit model derived using the loosely coupled transformer model is verified experimentally by using a frequency response analyzer. The experimental results confirmed that the sensitivity analysis can be accurately used for future system designs.

In this paper, the static and dynamic characteristics of discrete 650 V and 1200 V trench TO 247 SiC MOSFET is evaluated and compared with a similar current rating 1200 V planar gate discrete TO 247 SiC MOSFET. The new trench MOSFET has promising application for vehicle charging and auxiliary power supply application due to the lower on-state resistance and lower capacitance. Static characteristics for these devices are evaluated using a curve tracer for different device junction temperature. A common double pulse test (DPT) platform is developed to evaluate the switching loss at different device junction temperature ranging from 25°C to 175°C. The experimental setup and results are presented for different load currents and temperature.

The future power grid will involve increasing numbers of power converters while growing the complexity of the power systems. The future of the power converters is driven by developments in the wide-bandgap semiconductor devices. In this paper, a 50-kW string photovoltaic (PV) inverter designed and developed using all silicon carbide (SiC) semiconductor devices is presented. The inverter design includes an additively manufactured power block, symmetrical Y-core inductors for the ac-side filter, and advanced inverter controls for grid support functionality. This inverter uses the conventional three-phase voltage source inverter topology and optimizes the design for SiC-based devices. The paper includes details on power module design, heatsink optimization, symmetrical Y-core filter inductor design, inverter thermal design, and further experimental validation of the inverter performance. In addition to presenting the quantification of inverter efficiency and quality of the output, the paper presents the validation of advanced grid-support functions required by the IEEE 1547 standards for the interconnection of distributed energy resources.

In this paper, the effects of the resonant network characteristic and control variables on the dc-link capacitor of a wireless charger are investigated for electric vehicles, by deriving an analytical expression for the capacitance in terms of the resonant network parameters and system control variables. With this equation, the minimum dc-link capacitance needed can be obtained to keep the dc-link voltage ripple within a desired limit for a wide load range. A comparison between the conventional series-primary resonant networks in terms of the dc-link capacitance needs is presented as well as simulation results to validate the derived equation.

Enhancing power density and reliability of power electronics is extremely important in power electronics applications. One of the key challenges in the design process is to design the optimum heat sink. In this paper, an algorithm is proposed to design air-cooled heat sinks using genetic algorithm (GA) and finite element analysis (FEA) simulations. While the GA generates a population of candidate heat sinks in each iteration, FEA simulations are used to evaluate the fitness function of each. The fitness function considered in this paper is the maximum junction temperature of the semiconductor devices. With an approach that prefers “survival of the fittest”, a heat sink providing better performance than the conventional heat sinks is obtained. The simulation and experimental evaluations of the optimized air-cooled heat sink are also included in the paper.

This paper proposes an adaptive DC-bus stabilizer for single-phase grid-connected voltage source converter (VSC) with small-scale renewable energy integration. To enhance converter's power density, the conventional active power decoupling (APD) techniques were adopted to reduce the DC capacitance by compensating the inherent second-order harmonic power ripples in the single-phase VSC. However, it would potentially make the DC voltage vulnerable to transient power ripples, which is a critical issue for the grid-connected renewable energy source (RES) system during grid faults. The proposed DC-bus stabilizer can not only compensate the second-order harmonic power ripples at normal operation, but also enhance the fault ride-through capability of the converter. The circuit topology and its corresponding control strategy are presented, and then simulation results are provided to demonstrate the feasibility and validity of the proposed DC-bus stabilizer under normal operation and grid fault condition.

To reduce the consumption of non-renewable energy in the building sector, single-phase grid-connected voltage source converter (VSC) has been widely used to integrate distributed energy resources (DERs) into the building electrical network. As the increasing penetration of DERs into the electrical power system, new grid codes require the DERs should become more interactive and flexible while operating with the utility grid. Some functionalities may include grid fault operation and support capabilities, such as fault ride through, Volt/VAr support, etc. However, these new advanced functions might bring functionality conflict with the existing functions, such as anti-islanding protention. In this paper, the behaviors of single-phase grid-connected VSC under various grid conditions, such as voltage sag and unintentional power outage, are investigated. Following the analysis, a coordinated reactive control strategy including grid status identification criteria development and reactive curve designing, is proposed to enhance the performance of the converter on descriminating various grid status with multiple functionality conflict consideration. Simulation studies are presented to demonstrate the validity of the proposed control strategy.

Wireless charging of electric vehicles (EVs) is going to play a major role in electrification of transportation. This paper proposes to utilize an LCL tuned primary and series tuned secondary with a secondary buck regulator to achieve power transfer control by secondary side control only. Analytical expressions for base (primary) coil current and transformer turns ratio N required to transfer the required power at a certain input voltage is calculated for a given coil set. The required parameters are calculated for a 6.6 kW wireless charging system with a matched circular coil set. The proposed control scheme and analysis were validated through Saber Sketch simulations and by a 6.6 kW laboratory prototype. Experimental results for different load power settings at voltages of 290 V, 340 V, and 370 V are presented.

With the inherent benefits of high-voltage direct current (HVDC) transmission systems like long-distance high-power transmission with lesser losses and costs, easy integration of renewables, and others, increased presence of DC-AC grids is expected. One of the consequences of increased presence of power electronics is the reduced inertia in the grid, which is an emerging concern. Moreover, the long length of AC transmission lines result in the presence of weak grids (with low short-circuit ratio). To address these concerns, an advanced control algorithm is proposed to control the modular multilevel converter (MMC) based HVDC substation that is connected to a low-inertia weak-grid. The algorithm is based on optimization of control states like frequency, capacitor voltages, active power, and currents in the MMC. The performance of the proposed algorithm is validated in PSCAD/EMTDC to show the effectiveness of the proposed strategy.

So far, the charging functionality for vehicles has been integrated either into the traction drive system or to the dc-dc converters in plug-in electric vehicles (PEV). This study features a unique way of combining the wired and wireless charging functionalities with vehicle side boost converter and maintaining the isolation to provide a hybrid plug-in and wireless charging solution to the plug-in electric vehicle users. The proposed integrated charger combined with SiC technology shows the end-to-end and dc-to-dc system efficiencies of 85.9% and 88.9% for wireless charging mode, and 88.8% and 92.4% for the wired charging mode of operation.

Dynamic wireless charging is a possible cure for the range limitations seen in electric vehicles (EVs) once implemented in highways or city streets. The contribution of this paper is the use of experimental data to show that the expected energy gain from a dynamic wireless power transfer (WPT) system is largely a function of average speed, which allows the power level and number of coils per mile of a dynamic WPT system to be sized for the sustained operation of an EV. First, data from dynamometer testing is used to determine the instantaneous energy requirements of a light-duty EV. Then, experimental data is applied to determine the theoretical energy gained by passing over a coil as a function of velocity and power level. Related simulations are performed to explore possible methods of placing WPT coils within roadways with comparisons to the constant velocity case. Analyses with these cases demonstrate what system ratings are needed to meet the energy requirements of the EV and what effect longitudinal alignment has on WPT. The simulations are also used to determine onboard energy storage requirements for each driving cycle.

Provides an abstract for each of the tutorial presentations and a brief professional biography of each presenter. The complete presentations were not made available for publication as part of the conference proceedings.

Layer by layer, inch my inch, the world's first 3-D printed vehicle seemingly emerged from thin air during the 2014 International Manufacturing Technology Show. In a matter of two days, history was made at Chicago's McCormick Place, as the world's first 3-D printed electric car -named Strati, Italian for ·'Iayers·'-took its first test drive.

The market leaders in IGBT technology are now introducing next generation "six-pack" modules to enable increased power density and reduced cost for automotive traction drive applications. However, the potential gains offered by these modules can only be harvested using an optimized DC link with integrated capacitor/bus topology. Two integrated capacitor/bus solutions have been designed to support the new Infineon HybridPACK(TM) Drive module with the lowest possible myF/kW ratio and minimized equivalent series inductance. Simulation and design results are presented along with third party testing data for a complete inverter.

Several wireless charging methods are under development or available as an aftermarket option in the light-duty automotive market. However, there are not many studies detailing the vehicle integrations, particularly a fully integrated vehicle application. This paper presents the development, implementation, and vehicle integration of a high-power (>10 kW) wireless power transfer (WPT)-based electric vehicle (EV) charging system for a Toyota RAV4 vehicle. The power stages of the system are introduced with the design specifications and control systems including the active front-end rectifier with power factor correction (PFC), high frequency power inverter, high frequency isolation transformer, coupling coils, vehicle side full-bridge rectifier and filter, and the vehicle battery. The operating principles of the overall wireless charging system as well as the control system are presented. The physical limitations of the system are also defined that would prevent the system from operating at higher levels. The system performance is shown for two cases including unmatched (interoperable) and matched coils. The experiments are carried out using the integrated vehicle and the results are obtained to demonstrate the system performance including the stage-by-stage efficiencies with matched and interoperable primary and secondary coils.

Simulation of modular multilevel converter (MMC) based high-voltage direct current (HVDC) systems assumes significance due to their growing popularity. It could assist with the design of hardware, control systems of MMC and HVDC networks, and power system topology. However, simulation of MMC-HVDC using existing software takes a long time due to the presence of a large number of states and non-linear devices. This paper presents an ultra-fast single- or multi-CPU simulation algorithm to simulate the MMC-HVDC system based on state-space models and using hybrid discretization algorithm with a relaxation technique that reduces the imposed computational burden. Using the developed simulation algorithm, a control system is developed for an MMC-HVDC system that reduces the switching losses in the system.

This paper presents an analytical model for wireless power transfer system used in electric vehicle application. The equivalent circuit model for each major component of the system is described, including the input voltage source, resonant network, transformer, nonlinear diode rectifier load, etc. Based on the circuit model, the primary side compensation capacitance, equivalent input impedance, active / reactive power are calculated, and the model provides a guideline for parameter selection. In addition, the voltage gain curve from dc output to dc input is derived as well. A hardware prototype with series-parallel resonant stage was built to verify the developed model. The model was validated by comparing the experimental results from the hardware prototype.

This paper presents a detailed parametric sensitivity analysis for a wireless power transfer (WPT) system in an electric vehicle application. Specifically, several key parameters for sensitivity analysis of a series-parallel (SP) WPT system are derived first based on analytical modeling approach, which includes the equivalent input impedance, active / reactive power, and DC voltage gain. Based on the derivation, the impact of primary side compensation capacitance, coupling coefficient, transformer leakage inductance, and different load conditions on the DC voltage gain curve and power curve are studied and analyzed. It is shown that the desired power can be achieved by just changing frequency or voltage depending on the design value of coupling coefficient. However, in some cases both have to be modified in order to achieve the required power transfer at high efficiencies.

Integrated charger topologies that have been researched so far with dc-dc converters and the charging functionality have no isolation in the system. Isolation is an important feature that is required for user interface systems that have grid connections and therefore is a major limitation that needs to be addressed along with the integrated functionality. The topology proposed in this paper is a unique and a first of its kind topology that integrates a wireless charging system and the boost converter for the traction drive system. The new topology is also compared with an on-board charger system from a commercial electric vehicle (EV). The ac-dc efficiency of the proposed system is 85.1% and the specific power and power density of the onboard components is ~455 W/kg and ~320 W/l.

Integrated charger topologies that have been researched so far are with the dc-dc converters and the charging functionality usually have no isolation in the system. Isolation is an important feature that is required for user interface systems that have grid connections and therefore is a major limitation that needs to be addressed along with the integrated functionality. This study features a unique way of combining the wired and wireless charging functionalities with vehicle side boost converter integration and maintaining the isolation to provide the best solution to the plug-in electric vehicle (PEV) users. The new performance of the proposed architecture is presented for wired and wireless charging options at different power levels.

With efforts to reduce the cost, size, and thermal management systems for the power electronics drivetrain in hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), wide band gap semiconductors including silicon carbide (SiC) have been identified as possibly being a partial solution. This paper focuses on the development of a 10-kW all SiC inverter using a high power density, integrated printed metal power module with integrated cooling using additive manufacturing techniques. This is the first ever heat sink printed for a power electronics application. About 50% of the inverter was built using additive manufacturing techniques.

In a wireless power transfer (WPT) system, efficiency of the power conversion stages is crucial so that the WPT technology can compete with the conventional conductive charging systems. Since there are 5 or 6 power conversion stages, each stage needs to be as efficient as possible. SiC inverters are crucial in this case; they can handle high frequency operation and they can operate at relatively higher temperatures resulting in reduces cost and size for the cooling components. This study presents the detailed power module design, development, and fabrication of a SiC inverter. The proposed inverter has been tested at three center frequencies that are considered for the WPT standardization. Performance of the inverter at the same target power transfer level is analyzed along with the other system components. In addition, another SiC inverter has been built in authors' laboratory by using the ORNL designed and developed SiC modules. It is shown that the inverter with ORNL packaged SiC modules performs better than the inverter having commercially available SiC modules.

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.

This paper presents a new active overcurrent protection scheme for IGBT modules based on the evaluation of fault current level by measuring the induced voltage across the stray inductance between the Kelvin emitter and power emitter of IGBT modules. Compared with the commonly used desaturation protection, it provides a fast and reliable detection of fault current without any blanking time. Once a short circuit is detected, a current limiting and clamping function is activated to dynamically suppress the transient peak current, thus reducing the considerable energetic and thermal stresses induced upon the power device. Subsequently, a soft turn-off mechanism is employed aiming to reduce surge voltages induced by stray inductance under high current falling rate. Moreover, the proposed method provides flexible protection modes, which overcome the interruption of converter operation in the event of momentary short circuits. The feasibility and effectiveness of the proposed approach have been validated by simulation results with real component models in Saber. A Double Pulse Tester (DPT) based experimental test setup further verifies the proposed protection scheme.

Ac-ac matrix converters and cycloconverters require bi-directional switches, which are typically formed by two antiparallel thyristors or a two-switch (IGBT/MOSFETs) two-diode configuration. As silicon carbide (SiC) and gallium nitride (GaN) devices become more available, it is possible to have higher voltage FETs with low conduction and switching losses and reverse conduction capability, which allows the elimination of the diodes in a bidirectional switch. This paper will investigate a bidirectional switch formation that is formed by using two normally-on SiC JFETs in anti-series with no anti-parallel diodes.

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to system level variables such as battery state-of-charge and coil misalignment. To understand the power flow through the system this paper presents a novel approach to the system model and the impact of different control parameters on the load power. The implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation is also discussed.

This paper provides a behavioral model in Pspice for a silicon carbide (SiC) power MOSFET rated at 1200 V / 30 A for a wide temperature range. The Pspice model was built using device parameters extracted through experiment. The static and dynamic behavior of the SiC power MOSFET is simulated and compared to the measured data to show the accuracy of the Pspice model. The temperature dependent behavior was simulated and analyzed. Also, the effect of the parasitics of the circuit on switching behavior was simulated and discussed.

This paper presents recent research on several silicon carbide (SiC) power devices. The devices have been tested for both static and dynamic characteristics, which show the advantages over their Si counterparts. The temperature dependency of these characteristics has also been presented in this paper. Then, simulation work of paralleling operation of SiC power MOSFETs based on a verified device model in Pspice is presented to show the impact of parasitics in the circuit on the switching performance.

The purpose of this study is to determine the thermal feasibility of an air-cooled 55-kW power inverter with SiC devices. Air flow rate, ambient air temperature, voltage, and device switching frequency were studied parametrically by performing transient and steady-state simulations. The transient simulations were based on inverter current that represents the US06 supplemental federal test procedure from the US EPA. The results demonstrate the thermal feasibility of using air to cool a rectangular-shaped 55-kW SiC traction drive inverter. When the inverter model is subject to one or multiple current cycles, the maximum device temperature does not exceed 146°C for an inlet flow rate of 270 cfm, ambient temperature of 120°C, voltage of 650 V, and switching frequency of 20 kHz. The results show that the ideal blower power input for the entire inverter with a total inlet air flow rate of 540 cfm is 105 W.

This paper presents an analysis of single discrete silicon carbide (SiC) JFET and BJT devices and their parallel operation. The static and dynamic characteristics of the devices were obtained over a wide range of temperature to study the scaling of device parameters. The static parameters like on-resistance, threshold voltage, current gains, transconductance, and leakage currents were extracted to show how these parameters would scale as the devices are paralleled. A detailed analysis of the dynamic current sharing between the paralleled devices during the switching transients and energy losses at different voltages and currents is also presented. The effect of the gate driver on the device transient behavior of the paralleled devices was studied, and it was shown that faster switching speeds of the devices could cause mismatches in current shared during transients.

The purpose of this study is to determine the thermal feasibility of an air-cooled 55-kW power inverter with SiC devices. Air flow rate, ambient air temperature, voltage, and device switching frequency were studied parametrically by performing transient and steady-state simulations. The transient simulations were based on inverter current that represents the US06 supplemental federal test procedure from the US EPA. The results demonstrate the thermal feasibility of using air to cool a cylindrical-shaped 55-kW SiC traction drive inverter with axial-flow of air. When the inverter model is subject to one or multiple current cycles, the maximum device temperature does not exceed 164°C (327°F) for an inlet flow rate of 270 cfm, ambient temperature of 120°C, voltage of 650 V, and switching frequency of 20 kHz. The results show that the ideal blower power input for the entire inverter with a total inlet air flow rate of 540 cfm is 312 W.

With efforts to reduce the cost, size, and thermal management systems for the power electronics drivetrain in hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), wide band gap semiconductors including silicon carbide (SiC) have been identified as possibly being a partial solution. Research on SiC power electronics has shown their higher efficiency compared to Si power electronics due to significantly lower conduction and switching losses. This paper focuses on the development of a high power module based on SiC JFETs and Schottky diodes. Characterization of a single device, a module developed using the same device, and finally an inverter built using the modules is presented. When tested at moderate load levels compared to the inverter rating, an efficiency of 98.2% was achieved by the initial prototype.

Power electronics play an important role in electricity utilization from generation to end customers. Thus, high-efficiency power electronics help to save energy and conserve energy resources. Research on silicon carbide (SiC) power electronics has shown their better efficiency compared to Si power electronics due to the significant reduction in both conduction and switching losses. Combined with their high-temperature capability, SiC power electronics are more reliable and compact. This paper focuses on the development of such a high efficiency, high temperature inverter based on SiC JFET and diode modules. It involves the work on high temperature packaging (>200°C), inverter design and prototype development, device characterization, and inverter testing. A SiC inverter prototype with a power rating of 18 kW is developed and demonstrated. When tested at moderate load levels compared to the inverter rating, an efficiency of 98.2% is achieved by the initial prototype without optimization, which is higher than most Si inverters.

In this paper a comparison of performance of an hybrid electric vehicle with an all-silicon (Si), hybrid (Si and SiC), and an all-Silicon Carbide (SiC) inverters simulated for the standard US06 driving cycle is presented. The system model includes a motor/generator model, a boost converter model, and an inverter loss model developed using actual measured data. The drive train simulation results will provide an insight to the impact of SiC devices on overall system efficiency gains compared to Si devices over the drive cycle at different operating conditions.

This paper presents a study of silicon carbide (SiC) technology which includes device characterization and modeling, inverter simulation, and test results for several prototype inverters. The static and dynamic characteristics of discrete devices and half bridge modules are presented. Test results of a 55 kW hybrid inverter with SiC Schottky diodes and an 18 kW all-SiC inverter using SiC JFETs and Schottky diodes are demonstrated.

The purpose of this work is to provide validated models to estimate the performance of a SiC-based converter as a utility interface in battery systems. System design and modeling are described in detail. Simulations are done for both a SiC JFET converter and its Si counterpart based on the quality of tested devices. The simulation results indicate that in both charging and discharging modes, the SiC converter has a better performance compared to the Si one. (1) With the same heatsink size and ambient temperature, great advantages in efficiency and junction temperatures were found in the SiC-based converter. (2) With the same thermal limit, large savings in system weight and volume combined with a high efficiency were found in the SiC-based converter

Silicon carbide (SiC) power devices are expected to have an impact on power converter efficiency, weight, volume, and reliability. Presently, only SiC Schottky diodes are commercially available at relatively low current ratings. Oak Ridge National Laboratory has collaborated with Cree and Semikron to build a Si IGBT-SiC Schottky diode hybrid 55kW inverter by replacing the Si pn diodes in Semikron's automotive inverter with Cree's made-to-order higher current SiC Schottky diodes. This paper presents the developed models of these diodes for circuit simulators, shows inverter test results, and compares the results to those of a similar all-Si inverter.

Silicon carbide (SiC) power devices are expected to have an impact on power converter efficiency, weight, volume, and reliability. Presently, only SiC Schottky diodes are commercially available at relatively low current ratings. Oak Ridge National Laboratory has collaborated with Cree and Semikron to build a Si IGBT-SiC Schottky diode hybrid 55 kW inverter by replacing the Si pn diodes in Semikron's automotive inverter with Cree's made-to-order higher current SiC Schottky diodes. This paper shows the results obtained from testing this inverter and compares it to a similar all-Si inverter.

This paper presents a set of models for a SiC VJFET inverter from device level to system level. The simulations for SiC and Si inverters indicated that the SiC inverter has a much lower junction temperature, much less power loss, significantly enhanced energy efficiency, and a dramatic reduction in heatsink size as compared with the Si inverter. This demonstrated the technical feasibility and benefits of the all-SiC inverter. In addition to the simulations, experimental tests have also been conducted on SiC VJFETs and Schottky diodes for parameter extraction.

Silicon carbide (SiC) unipolar devices have much higher breakdown voltages because of the ten times greater electric field strength of SiC compared with silicon (Si). 4H-SiC unipolar devices have higher switching speeds due to the higher bulk mobility of 4H-SiC compared to other polytypes. Four commercially available SiC Schottky diodes at different voltage and current ratings, an experimental VJFET, and MOSFET samples have been tested to characterize their performance at different temperatures. Their forward characteristics and switching characteristics in a temperature range of -50degC to 175degC are presented. The results of the SiC Schottky diodes are compared with those of a Si pn diode with comparable ratings

The development of semiconductor devices is vital for the growth of power electronic systems. Modern technologies like voltage source converter (VSC) based HVDC transmission has been made possible with the advent of power semiconductor devices like GTO thyristors and their high power handling capability. Silicon carbide is the most advanced material among the available wide band gap semiconductors and most SiC devices are currently in the transition from research to manufacturing phase. This paper presents the modeling and design of a loss model for a 4H-SiC GTO thyristor device. The device loss model has been developed based on the device physics and device operation, and simulations have been conducted for various operating conditions. The loss model was integrated in the HVDC transmission system model to study the effects of the Si and SiC devices on the system. The paper focuses on the comparison of Si devices with SiC devices in terms of efficiency and cost savings for a HVDC transmission system.

The increase in use of power electronics in transmission and distribution applications is the driving force for development of high power devices. Utility applications like FACTS and HVDC require cost effective and highly efficient converters with high power ratings. SiC power devices have some exceptional physical properties that make them highly reliable at high power, high temperature, and high frequencies. This paper presents the modeling of temperature dependent 4H-SiC GTO thyristor and p-n diode loss models. The conduction and switching losses of the devices for various operating conditions have been simulated and compared for SiC and Si devices. These loss models are integrated with an HVDC transmission system to study the effect of Si and SiC devices on the system in terms of system efficiency and system cost management.

Silicon (Si) unipolar devices are limited in breakdown voltages because of the low electric field strength of the material. Silicon carbide (SiC) unipolar devices, on the other hand, have 10 times greater electric field strength and hence they have much higher breakdown voltages compared with Si. They also have low static and dynamic losses compared with Si devices. Four commercially available SiC Schottky diodes at different voltage and current ratings and an experimental SiC VJFET sample have been tested to characterize their performance at different temperatures. Their forward characteristics and switching characteristics in a temperature range of -50 /spl deg/C to 175 /spl deg/C are presented. The results for the SiC Schottky diodes are compared with the results for a Si pn diode with comparable ratings. The experimental data were analyzed to obtain the device performance parameters like the on-state resistance and the switching losses.