Optimal Gate Driving Strategy for Si/SiC Hybrid Switch-Based 3L-ANPC Inverter with Improved Output Capacity

A silicon IGBT/silicon carbide MOSFET hybrid switch (Si/SiC HyS)-based three-level active neutral point clamped (3L-ANPC) inverter has been proposed to achieve a high inverter efficiency with relatively low device cost. However, the conventional gate driving strategy will concentrate all the high-frequency switching losses on the small current-rated SiC MOSFETs within the Si/SiC HyS. The power devices will suffer from thermal unbalance which limits the output capacity of the Si/SiC HyS-based 3L-ANPC inverter. To improve the output capacity of the Si/SiC HyS-based 3L-ANPC inverter, an optimal gate driving (OGD) strategy is proposed in this paper. The Si/SiC HyS-based 3L-ANPC inverter will operate in "energy-efficient mode" to maximize inverter efficiency under rated power. When overload operation is needed, the inverter will perform "thermal-balance mode" to balance the thermal distribution and maximize the output capacity. A thermal model-based junction temperature balancing method is proposed in this paper to balance the junction temperature to improve the output capacity of the Si/SiC HyS-based 3L-ANPC inverter. The proposed OGD strategy is validated experimentally on a 3.5kW Si/SiC HyS-based 3L-ANPC inverter platform. The experimental results demonstrate that the device temperatures are distributed more uniformly with the proposed OGD strategy, which also improves the output capacity of the Si/SiC HyS-based 3L-ANPC inverter.