Simplified Universal Fault-Tolerant Direct Torque Control of FPFTPM Motor With Steady-Healthy Design Under Open-Circuit Fault

A simplified universal fault-tolerant direct torque control (FTDTC) strategy of five-phase fault-tolerant permanent magnet (FPFTPM) motors under various open-circuit faults is presented in this article. In the proposed FTDTC strategy, the fault-tolerant currents are derived from the fault-tolerant mechanism analysis and steady-healthy design. The problems of existing FTDTC strategies that need to change coordinate transformation and add extra voltage compensation can be overcome. Thus, the minimal control drive system reconfiguration under different faults can be realized in the real sense. Especially, the steady-healthy controller is designed to suppress the torque ripples and achieve the high-quality torque given even under fault operation conditions; then, it is not necessary to set a special voltage vector or add a PI controller. Furthermore, the FTDTC strategy is improved to be realized under the dq coordinate system based on the flux adaption. Hence, the reduced d-axis current under different operating conditions, including fault conditions, can be ensured. This FTDTC strategy without any control reconfiguration is proposed under the premise of ensuring good performance during both healthy and fault operations. Finally, the simulation and experimental results for an FPFTPM prototype are offered to verify the feasibility of the proposed strategy.

Automated summary

This article presents a simplified universal fault-tolerant direct torque control strategy for five-phase fault-tolerant permanent magnet motors under various open-circuit faults. The strategy overcomes the limitations of existing strategies and achieves minimal control drive system reconfiguration under different faults. It also ensures high-quality torque given under fault operation conditions. The strategy includes a steady-healthy controller to suppress torque ripples and a flux adaption-based dq coordinate system for reduced d-axis current in different operating conditions. The feasibility of the proposed strategy is verified through simulation and experimental results.