A Low-Voltage Low-Loss Active Reflected Wave Canceller for a Medium-Voltage SiC Motor Drive Based on a Generalized Multilevel Inverter Topology

Multilevel topologies with SiC devices for medium voltage (MV) motor drive have advantages to reduce the harmonics and device voltage stress as well as to increase the efficiency. However, with the application of SiC devices, the reflected wave phenomenon still happens in multilevel motor drive due to its high dv/dt, resulting in overvoltage at motor terminals. This paper proposed a T-type circuit based active reflected wave canceller (ARWC) to suppress the overvoltage of a M-level motor drives with reduced voltage rating of Vdc/(M-1). A coupled inductor is applied to isolate the ARWC output and the main inverter. In addition, the coupled inductor is designed with a small resistor to allow low current flowing into ARWC. The proposed ARWC configuration can be applied for general multilevel topologies. A 3-level ANPC converter with 3.3 kV SiC device is built in the laboratory. A 1.2 kV SiC module is applied in the proposed ARWC. The experimental results at 1.6 kV Vdc and 16 A (RMS) load current with and without proposed ARWC are provided and compared to verify the validity of proposed method.