Fault-Tolerant Control of Paralleled-Voltage-Source-Inverter-Fed PMSM Drives

The aim of this paper is to study the fault-tolerant control strategies when faults occur in paralleled-inverter-fed permanent-magnet-synchronous-motor drives. Different from removing the faulty inverter channels completely, this paper proposes and compares three fault-tolerant control strategies, which fully use all the healthy phase legs, including those in faulty inverters. The three schemes are called "normal channel direct compensation," "normal channel asymmetric currents," and "equivalent current value compensation," respectively. The proposed control schemes not only provide smooth torque but also have smaller copper loss under open-circuit faults. The corresponding principles and design criteria of control are given. Moreover, the proportional-resonant current controller is designed to track the asymmetrical current references of fault-tolerant control and avoid the possible circulating currents among paralleled inverter channels. The experiments are given to verify and compare the performance of the proposed fault-tolerant control schemes.