A novel switching loss minimized PWM method for a high switching frequency three-level inverter with a SiC clamp diode

The previous papers introduce the inverters replacing Si diode with SiC diode to reduce the switching loss. In the NPC inverter, the switching loss is also reduced by replacing device in the clamp diode. However, the switching loss in IGBT is large and the reduced switching loss cannot be still neglected. This paper presents the reverse recovery characteristic according to the change of switching states when Si diode and SiC diode are used as clamp diode and proposes a method to minimize the switching loss containing the reverse recovery loss in NPC inverter at low modulation index. It is expected that the reverse recovery loss can be almost eliminated and the switching loss can be considerably reduced by the proposed method. Therefore, it is also possible to operate the inverter at the higher frequency with the better system efficiency. The effectiveness of the proposed method is verified by numerical analysis.