Design and Control of a Fault Tolerant Permanent Magnet Motor with Independently Optimized Phase and Pole Counts

Multi-phase motors offer a high reliability solution for safety-critical applications as they can operate under some fault conditions with reduced performance. Permanent magnet synchronous motors (PMSMs) provide high torque density and efficiency. This study performed a thorough parametric analysis using 2-D magnetostatic and transient finite element analysis (FEA) to individually optimize PMSMs with double-layer or single-layer windings. There is no defined relation between rotor pole pair and stator phase numbers for better optimization. This paper uses an H-bridge for each phase to control the phases independently and introduces an optimal approach for power compensation during the open circuit fault. This method achieves the minimum torque ripple and the minimum increase in DC copper losses. As expected, the topology using a double-layer winding and a Halbach array was found to outperform the other topologies with regards to torque density and efficiency.