Investigation of Open-Circuit Fault-Tolerant Strategy in a Modular Permanent Magnet Synchronous In-Wheel Motor Based on Electromagnetic-Thermal Analysis

This article investigates the asymmetric temperature distribution of a modular permanent magnet (PM) synchronous in-wheel motor under fault conditions, and based on this, proposes a fault-tolerant (FT) strategy named minimum temperature difference strategy (MTDS) to avoid the high temperature appearing at local winding. First, the modular motor system and the FT principle are introduced, and the reconfiguring fundamental magneto motive force (MMF) under open-circuit of one phase in one module is deduced. Second, the loss and temperature distributions of the motor with normal operation are analyzed by the coupled electromagnetic-thermal method. And the mutual verification between simulation and experiment is adopted to separate the copper losses, iron losses, and PM losses from total losses. Furthermore, the asymmetric temperature distributions of the motor operating with part of modules are analyzed in detail. Finally, the influence of the faulty windings on the temperature of healthy windings is investigated, and the FT strategy of MTDS is proposed. The asymmetric temperature distributions of the motor under various FT strategies are compared. The result shows that the MTDS can significantly reduce the maximum temperature of the windings and makes the winding temperature distribution more uniform.