WBG-based 20 kW dc-dc converter for interfacing solar energy with the hardware testbed.
Rooftop solar panels at UTK 11th Street parking garage adjacent to the Min Kao Building can produce a maximum of 21 kW of solar power. The aim of this project is to build an efficient dc-dc converter to interface this solar energy with CURENT’s reconfigurable grid emulator hardware testbed. This high power buck-boost type of interleaved dc-dc converter accepts input power from the solar panels at an input voltage of 200 V, and can supply a maximum power of 20 kW to CURENT’s reconfigurable grid emulator hardware testbed at an output voltage level varying from 50 V to 600 V. Apart from its high power and high current handling capability, this converter also uses state of the art wide band gap devices as its switches.
Implementation of interleaved converter is not new. There are many applications of interleaved buck or interleaved boost topology, but implementation of interleaved buck-boost topology is not common. Therefore, it is expected that, if successful, this application will be an important addition in the research of buck boost interleaved converters with a high number of phases incorporating WBG devices.
20 kW Solar Array on Roof of 11th Street Parking Garage
Traditional interleaved converters can be further improved by adding other distinctive functionalities and features into its operation, e.g. operating the converter in DCM mode, applying ZVS or ZCS etc. An effort will be made to propose a more improved topology of buck boost interleaved converter which will incorporate innovative features resulting in reduced loss and smooth converter operation.
This high power buck boost type dc-dc converter needs to withstand high voltage (600 V), and high output current (maximum 400 A). To share this high current, N number of parallel stages will be designed. These stages will also be phase shifted to achieve advantages like input and output voltage ripple cancellation, improved load transient response, etc.
As the number of interleaved stages increases, the control complexity increases too. The main challenge of this research would be to implement innovative ideas into the operation and control circuitry of this converter that would led to a very smoothly controlled and efficient converter. Designing proper cooling system would also be crucial issue of this research.
Prior to hardware implementation of this converter, detailed analysis of the converter steady state operation, and mathematical modelling of converter dynamics incorporating losses will be done.
How WBG Can Help
As this is a high power (600V, 400A) converter with the need for high efficiency, use of WBG devices as its switches is very suitable. Also, use of wideband gap devices will enable implementing high switching frequency without incurring much switching losses compared to conventional Si based implementation. Using WBG devices would also be beneficial in terms of weight and high power density.
- Manashi Roy
- Mark Nakmali