SiC-MOSFETを用いたZソースインバータの上下短絡動作によるボディダイオード無通電運転

抄録

A Z-source inverter (ZSI) can achieve boost and inverter function in single stage without a boost converter by using a short-through mode which shorts legs of the inverter. And it can be more high power density by employing a SiC-MOSFET which can drive high frequency operation. When employing the SiC-MOSFET for a conventional inverter, the SiC-MOSFET needs an additional SiC-SBD connected in parallel to avoid body-diode conduction in dead-time. This SiC-SBD becomes disadvantage for size reduction of the circuit, however conducting the body-diode is cause of degradation of the SiC-MOSFET and decreases reliability of the circuit. Thus, to remove the SiC-SBD from the the conventional inverter is difficult. This paper proposes to eliminate the body-diode conduction in the SiC-MOSFET on the Z-source inverter by using short-through operation without an additional SiC-SBD. From experimental investigation using a quasi-Z-source inverter which is one of the Z-source topology, it was confirmed that a current does not flow into the SiC-MOSFET body-diode by using the proposed space vector modulation including the short-through operation. This result shows that the Z-source inverter can take full advantage of the SiC-MOSFET.