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Madhu Chinthavali

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E-mail:
vog.lnro@milavahtnihc
Phone: 865-946-1411
Fax: 865-946-1262
Address: Oak Ridge National Laboratory
PO Box 2008 MS6472
Oak Ridge, TN 37831-6472


Biography

Madhu Sudhan Chinthavali received his M.S. degree in electrical engineering at The University of Tennessee in December 2003. He received a B.E. degree in electrical engineering in 2000 from Bharathidasan University , India . He is presently a staff member in the Power Electronics and Electric Machinery Group of the Oak Ridge National Laboratory.

Ongoing Research Projects

Publications


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Journal Papers
Title
Year
  • Suman Debnath; Madhu Chinthavali
    IEEE Transactions on Industrial Electronics
    2018

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    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.

  • John M. Miller; Omer C. Onar; Madhu Chinthavali
    IEEE Journal of Emerging and Selected Topics in Power Electronics
    2015

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    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.

  • Burak Ozpineci; Madhu Sudhan Chinthavali; Leon M. Tolbert; Avinash S. Kashyap; H. Alan Mantooth
    IEEE Transactions on Industry Applications
    2009

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    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.

Conference Papers
Title
Year
  • Zhiqiang Jack Wang; Fei Yang; Steven Campbell; Madhu Chinthavali
    2018 IEEE Applied Power Electronics Conference and Exposition (APEC)
    2018

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    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.

  • Omer C. Onar; Madhu Chinthavali; Steven L. Campbell; Larry E. Seiber; Cliff P. White; Veda P. Galigekere
    2018 IEEE Transportation Electrification Conference and Expo (ITEC)
    2018

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    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.

  • Fei Yang; Zhiqiang Jack Wang; Zheyu Zhang; Steven Campbell; Fred Wang; Madhu Chinthavali
    2018 IEEE Applied Power Electronics Conference and Exposition (APEC)
    2018

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    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.

  • Suman Debnath; Andrew Foote; Omer C. Onar; Madhu Chinthavali
    2018 IEEE Transportation Electrification Conference and Expo (ITEC)
    2018

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    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.

  • A. Foote; O. C. Onar; S. Debnath; M. Chinthavali; B. Ozpineci; D. E. Smith
    2018 IEEE Transportation Electrification Conference and Expo (ITEC)
    2018

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    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.

  • Saeed Anwar; Zhiqiang Jack Wang; Madhu Chinthavali
    2018 IEEE Transportation Electrification Conference and Expo (ITEC)
    2018

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    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.

  • Veda P. Galigekere; Omer Onar; Jason Pries; Shenli Zou; Zhiqiang Wang; Madhu Chinthavali
    2018 IEEE Transportation Electrification Conference and Expo (ITEC)
    2018

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    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.

  • Madhu Chinthavali; Zhiqiang Jack Wang; Steven Campbell; Tong Wu; Burak Ozpineci
    2018 IEEE Applied Power Electronics Conference and Exposition (APEC)
    2018

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    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.

  • Rong Zeng; Zhiqiang Jack Wang; Madhu Sudhan Chinthavali
    2017 IEEE Energy Conversion Congress and Exposition (ECCE)
    2017

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    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.

  • Rong Zeng; Zhiqiang Wang; Madhu Sudhan Chinthavali
    2017 IEEE Transportation Electrification Conference and Expo (ITEC)
    2017

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    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.

  • Tong Wu; Burak Ozpineci; Madhu Chinthavali; Zhiqiang Wang; Suman Debnath; Steven Campbell
    2017 IEEE Transportation Electrification Conference and Expo (ITEC)
    2017

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    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.

  • Suman Debnath; Madhu Chinthavali
    2017 IEEE 12th International Conference on Power Electronics and Drive Systems (PEDS)
    2017

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    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.

  • Nomar S. González-Santini; Burak Ozpineci; Madhu Chinthavali; Fang Zheng Peng
    2017 IEEE Transportation Electrification Conference and Expo (ITEC)
    2017

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    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.

  • Veda P. Galigekere; Omer C. Onar; Madhu Chinthavali; Zhiqiang Jack Wang
    2017 IEEE Energy Conversion Congress and Exposition (ECCE)
    2017

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    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.

  • Michael A. Brubaker; Terry A. Hosking; Tomas Reiter; Laura D. Marlino; Madhu S. Chinthavali
    PCIM Europe 2016; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management
    2016

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    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.

  • Omer C. Onar; Steven L. Campbell; Larry E. Seiber; Cliff P. White; Madhu Chinthavali
    2016 IEEE Energy Conversion Congress and Exposition (ECCE)
    2016

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    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 (EV) 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 communications, systems are presented. Aftermarket conversion approaches including the WPT on-board charger (OBC) 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.

  • Madhu Chinthavali; Zhiqiang Jack Wang
    2016 IEEE Energy Conversion Congress and Exposition (ECCE)
    2016

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    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.

  • Madhu Chinthavali
    2016 International Symposium on 3D Power Electronics Integration and Manufacturing (3D-PEIM)
    2016

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    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.

  • Suman Debnath; Madhusudhan Chinthavali
    2016 IEEE Energy Conversion Congress and Exposition (ECCE)
    2016

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    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.

  • Madhu Chinthavali; Omer C. Onar
    2016 IEEE Transportation Electrification Conference and Expo (ITEC)
    2016

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    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.

  • M. Chinthavali; O. C. Onar; S. L. Campbell; L. M. Tolbert
    2016 IEEE Applied Power Electronics Conference and Exposition (APEC)
    2016

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    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.

  • Madhu Chinthavali; Zhiqiang Wang; Steven Campbell
    2016 IEEE Transportation Electrification Conference and Expo (ITEC)
    2016

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    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.

  • Andrew Foote; Burak Ozpineci; Madhu Chinthavali; Jan-Mou Li
    2016 IEEE PELS Workshop on Emerging Technologies: Wireless Power Transfer (WoW)
    2016

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    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.

  • Omer C. Onar; Steven L. Campbell; Larry E. Seiber; Cliff P. White; Madhu Chinthavali
    2016 IEEE Transportation Electrification Conference and Expo (ITEC)
    2016

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    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.

  • M. Chinthavali; O. C. Onar; S. L. Campbell; L. M. Tolbert
    2015 IEEE Energy Conversion Congress and Exposition (ECCE)
    2015

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    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.

  • Madhu Chinthavali; Curt Ayers; Steven Campbell; Randy Wiles; Burak Ozpineci
    2014 IEEE Workshop on Wide Bandgap Power Devices and Applications
    2014

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    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.

  • Omer C. Onar; Madhu Chinthavali; Steven Campbell; Puqi Ning; Cliff P. White; John M. Miller
    2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014
    2014

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    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.

  • Lixin Tang; Madhu Chinthavali; Omer C. Onar; Steven Campbell; John M. Miller
    2014 IEEE Applied Power Electronics Conference and Exposition - APEC 2014
    2014

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    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.

  • Madhu Sudhan Chinthavali; Omer C. Onar; John M. Miller; Lixin Tang
    2013 IEEE Energy Conversion Congress and Exposition
    2013

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    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.

  • Zhiqiang Wang; Xiaojie Shi; Leon M. Tolbert; Benjamin J. Blalock; Madhu Chinthavali
    2013 Twenty-Eighth Annual IEEE Applied Power Electronics Conference and Exposition (APEC)
    2013

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    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.

  • M. Saadeh; Madhu S. Chinthavali; Burak Ozpineci; H. A. Mantooth
    2013 IEEE Energy Conversion Congress and Exposition
    2013

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    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.

  • Yutian Cui; Madhu S. Chinthavali; Fan Xu; Leon M. Tolbert
    2012 IEEE International Symposium on Industrial Electronics
    2012

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    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.

  • Yutian Cui; Madhu Chinthavali; Leon M. Tolbert
    2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC)
    2012

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    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.

  • Madhu Chinthavali; Jacob F. Christopher; Rao V. Arimilli
    2012 Twenty-Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC)
    2012

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    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.

  • Madhu Chinthavali; Puqi Ning; Yutian Cui; Leon M. Tolbert
    2011 Twenty-Sixth Annual IEEE Applied Power Electronics Conference and Exposition (APEC)
    2011

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    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.

  • Madhu Chinthavali; Jonathan A. Tawfik; Rao V. Arimilli
    2011 IEEE Energy Conversion Congress and Exposition
    2011

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    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.

  • M. Chinthavali; P. Otaduy; B. Ozpineci
    2010 IEEE Energy Conversion Congress and Exposition
    2010

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    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.

  • Hui Zhang; Leon M. Tolbert; Jung Hee Han; Madhu S. Chinthavali; Fred Barlow
    2010 Twenty-Fifth Annual IEEE Applied Power Electronics Conference and Exposition (APEC)
    2010

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    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.

  • M. Chinthavali; L. M. Tolbert; H. Zhang; J. H. Han; F. Barlow; B. Ozpineci
    The 2010 International Power Electronics Conference - ECCE ASIA -
    2010

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    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.

  • Madhu Chinthavali; Hui Zhang; Leon M. Tolbert; Burak Ozpineci
    2009 Brazilian Power Electronics Conference
    2009

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    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.

  • B. Ozpineci; M. S. Chinthavali; L. M. Tolbert; A. Kashyap; H. A. Mantooth
    Twenty-First Annual IEEE Applied Power Electronics Conference and Exposition, 2006. APEC '06.
    2006

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    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.

  • Hui Zhang; Leon M. Tolbert; Burak Ozpineci; Madhu S. Chinthavali
    Conference Record of the 2006 IEEE Industry Applications Conference Forty-First IAS Annual Meeting
    2006

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    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

  • H. Zhang; L. M. Tolbert; B. Ozpineci; M. S. Chinthavali
    Fourtieth IAS Annual Meeting. Conference Record of the 2005 Industry Applications Conference, 2005.
    2005

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    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.

  • M. S. Chinthavali; B. Ozpineci; L. M. Tolbert
    Twentieth Annual IEEE Applied Power Electronics Conference and Exposition, 2005. APEC 2005.
    2005

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    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

  • B. Ozpineci; M. S. Chinthavali; L. M. Tolbert
    2005 IEEE Vehicle Power and Propulsion Conference
    2005

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    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.

  • M. Chinthavali; L. M. Tolbert; B. Ozpineci
    IEEE Power Engineering Society General Meeting, 2004.
    2004

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    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.

  • M. S. Chinthavali; L. M. Tolbert; B. Ozpineci
    Conference Record of the 2004 IEEE Industry Applications Conference, 2004. 39th IAS Annual Meeting.
    2004

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    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.

  • M. S. Chinthavali; B. Ozpineci; L. M. Tolbert
    Power Electronics in Transportation (IEEE Cat. No.04TH8756)
    2004

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    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 °C to 175 °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.