A Symmetrical Hybrid Five-Level Inverter for High-speed PMSM Drives

This paper presents a symmetrical hybrid five-level inverter for high-speed permanent magnet synchronous motor (PMSM) drives. A midpoint voltage balance method is carried out to control the dc-link capacitor voltages based on hybrid modulation method. A speed sensorless control system using model reference adaptive is also introduced. In order to demonstrate the feasibility of this topology and control method, a 300kW prototype with high-speed SiC-MOSFETs and high-voltage IGBTs is build. Experimental results indicates that the maximal fundamental frequency can reach to 1500Hz and the maximal motor speed exceeds 10000 rpm.