Key points are not available for this paper at this time.
In this paper, the performance of active voltage balancing of series-connected SiC MOSFETs applied in the medium voltage (MV), bidirectional, series resonant dual active bridge (SRDAB), intended for interfacing battery energy storage (BES), is presented. As shown in the simulation study, throughout standard charging/discharging of BES, the battery voltage is changing, which forces various turn-off conditions of series-connected SiC MOSFETs in SRDAB – the switching current may be either positive (hard turn-off), close to 0 A (zero current switching – ZCS) or negative (zero voltage switching – ZVS). To provide an efficient voltage balancing technique, all mentioned turn-off cases were comprehensively analyzed, indicating the primary sources of voltage imbalance. For voltage equalization between stacked transistors in a wide operating range, the combination of an active gate delay technique with small, external SMD capacitors was proposed. A simple and effective approach to choosing additional capacitor values was also presented. Finally, the performance of series-connected SiC MOSFETs with an applied balancing approach in a 10 kW SRDAB prototype was successfully validated – the equal voltage distribution between stacked transistors was ensured, while the additional power losses introduced by the balancing circuit were negligible.
Trochimiuk et al. (Wed,) studied this question.