Open-Circuit Fault-Tolerant Control of Dual Three-Phase Open-Winding Machine Drive With a Floating Capacitor

The multiphase open-winding topology with a floating capacitor (FC) offers significant advantages, including broad control flexibility, high reliability, and strong fault-tolerant capabilities. However, the FC adds extra control constraints that need to be taken into consideration under various operating conditions. This article investigates the reliability of the FC and the voltage utilization of the main inverter (MI) under open-circuit fault-tolerant control (FTC). Based on the generalized symmetrical components theory, the current configuration and instantaneous power of the harmonic plane under FTC are analyzed. The analysis reveals that the instantaneous power of the harmonic plane introduces a second-order harmonic into the FC voltage, which affects the reliability of the system. Consequently, an optimized FTC method is proposed based on the characteristics of the topology. The performance of the proposed FTC method is verified experimentally in a dual three-phase open-winding synchronous reluctance machine system, achieving optimized FTC of the topology and expanding the speed operating range of the machine under FTC.