A SiC-based T-type three-phase three-level gridtied inverter

Due to the high thermal conductivity and the wide band gap, SiC power devices have many advantages against Si power devices such as higher operation temperature, higher breakdown electric field, higher switching speed and less switching loss. In this paper, a SiC-based T-type three-level topology is investigated. Considering the body diode characteristics of SiC power MOSFETs, three kinds of bidirectional switching circuits are presented and compared. One of them, with the lowest conduction loss, is used as the neutral point clamping branch of the T-type three-level inverter. Operation modes and modulation strategy of this inverter are analyzed. A 6 kW prototype using SiC MOSFET is built. The efficiency is tested and compared with a Si-based prototype. Experimental results show that using SiC power devices can improve the conversion efficiency obviously.