Investigation of eliminating free-wheeling diode conduction of Z-source inverter using SiC-MOSFET

In this paper, the current paths in the circuit of Z-source inverter using SiC-MOSFET are studied. The Z-source inverter can boost the input voltage using short-through operation, and also invert the DC voltage to AC voltage. Short-through operation is able to eliminate the free-wheeling diodes. This leads to reduce the number of semiconductor devices used in motor drive system with boost function. In the free-wheeling operation, the current flows through the reverse conducting SiC-MOSFET, and never flows the body-diode of SiC-MOSFET. Therefore, the degradation of SiC-MOSFET due to body-diode bipolar action is not needed to take account. These phenomena are examined experimentally. And it is concluded that SiC-MOSFET is suitable for high-performance high-reliable and low-cost Z-source inverter.