A Three-Phased Multilevel Converter for High-Power Induction Motors
A new converter topology for drives is presented in this paper: a three-phase multilevel converter with separately regulated dc power supplies. The dc voltages are provided by medium-frequency dc–dc converters. The applications for the converter are especially high-power traction systems, where the voltage applied to the induction motor is bigger than 1 kV. The motor current is of a very high quality, compared to a classical three-phase converter. This allows keeping the switching frequency low by using phase-shifted pulsewidth modulation (PWM) carriers. Different modulation methods have been developed and simulated. Experimental tests have been made on a 12-kW prototype.