Design Optimisation of an 8-pole Line-Start Permanent-Magnet Synchronous Motor

This paper presents an optimisation study of an 8-pole, 3-phase, 1kW line-start permanent magnet synchronous motor (LSPMSM) designed based on a benchmark induction motor (IM). The initial IM (IM0) is designed using a machine sizing technique and then the initial LSPMSM (L0) is designed based on some modifications in the rotor of the IM0. The finite element method (FEM) is employed to analyze the motor's performance. The initial LSPMSM (L0) operates with higher efficiency and power factor compared with the IM0. L0 efficiency is categorized in the IE4 efficiency standard class while IM0 efficiency is in the IE3 class. Then, IM0 and L0 are individually optimised based on a FEM optimisation technique using genetic algorithm (GA) to improve their transient and steady-state performance through maximizing the starting torque and the efficiency as two optimisation objectives, respectively. The optimised LSPMSM (L1) has better performance in terms of the starting torque (transient representative) and the efficiency (steady state representative) in comparison to other L0. The results indicate that, it is not necessarily true that a LSPMSM designed based on an optimised IM has better performance than a LSPMSM design based on a non-optimised IM (in this case L0).