Fault-tolerant operation for five-phase permanent magnet synchronous machine drives with five-phase six-leg inverter

Five-phase permanent magnet synchronous machine (PMSM) can operate under open-circuit faults with the appropriate current regulations. However, the traditional current regulations based on the five-phase half-bridge inverter have to satisfy the constraint of zero neutral point current, which limits the fault-tolerant performance of the machine. Thus, this paper investigates the current regulation based on the five-phase six-leg (FPSL) inverter, which relieves the zero-neutral point current limitation, and both current regulations considering the maximum torque (MT) and minimum copper loss (MC) are derived under different open-circuit conditions. The cost of the system has increased, but with the new regulations, better fault-tolerant operation capability of the machine can be obtained under all kinds of open-circuit faults. Moreover, with the introduction of the neutral point current, the machine can work under triple-phase open-circuit faults. In conclusion, the proposed control scheme based on the FPSL inverter expands the fault-tolerant operation capability of the five-phase PMSM. The experiment results prove the effectiveness of the proposed current regulation on increasing average torque or reducing copper loss under fault-tolerant operation.