Soft switching circuit of high-frequency active neutral point clamped inverter based on SiC/Si hybrid device

Abstract

Although the silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET) is superior to the conventional silicon (Si) insulated gate bipolar transistor in terms of switching performance, the switching losses of SiC devices increase rapidly by hard switching when the switching frequency (fsw) increase to hundreds of kilohertz (kHz). This paper proposes an auxiliary zero-voltage-transition circuit to realize zero-voltage-switching for all of the high-frequency main switches of the active neutral point clamped (ANPC) inverter based on a SiC/Si hybrid device, and zero-current-switching for all of the auxiliary switches. Through soft switching, the switching losses and anti-parallel diode reverse recovery losses of high-frequency SiC MOSFET switches can be further reduced. First, the circuit topology and the operation principle of the soft switching are detailed followed by the design procedure of the parameters. Then, the efficiencies of hard switching and soft switching ANPC inverters are compared with fsw changing from 10 to 200 kHz. To further improve the efficiency of the soft-switching inverter, two improved methods are proposed. The two proposed methods are auxiliary switches paralleling the external diode and utilizing synchronous rectification technology. Finally, a 1 kW, up to 200 kHz frequency ANPC inverter has been built to validate the above analysis.