Optimal design of a PM-assisted rotor of a 110 kW reluctance synchronous machine

This work describes the optimum design of a permanent magnet assisted reluctance rotor of a 110 kW reluctance synchronous machine for traction applications. Previous studies show that the performance of the reluctance synchronous machine, as compared to the induction machine, vastly deteriorates as the flux-weakening operating region is widened. To address this problem, use of thin bonded permanent magnet sheet material inside the flux barriers of the reluctance rotor is made to improve the performance of the reluctance synchronous machine especially in the flux-weakening region. A design optimisation algorithm is implemented to minimise the volume and hence the cost of the permanent magnet material subject to voltage and torque constraints of the machine. It is shown clearly that with optimum amount of permanent magnet material included the performance of the reluctance synchronous machine, in terms of torque and supply voltage, is significantly improved and compares favorably with that of induction machine at both rated and maximum speeds.