Design and Control Strategy of High Voltage Power Module for Double Pulse Testing Applications of Wide Band Gap Devices

Double pulse test (DPT) circuits are widely used to characterize a wide band gap power device performance under hard switching operation. This paper proposes the control strategy for a two-stage high voltage power module (HVPM) as the voltage source of DPT circuit. The front-end LLC converter ensures features of high conversion efficiency and galvanic isolation, whereas the back-end buck converter regulates the output voltage. After the input capacitor of the DPT circuit is fully charged, the HVPM will be operated in light load conditions and is hard to regulate output voltage by conventional control strategy. Therefore, an enhanced control strategy with high efficiency and fast transient response is proposed and developed for the HVPM under the light load or no load condition. Finally, a 200W prototype circuit with both simulation and experimental results demonstrates the performance of the control strategy.