Magnetic circuit design of IPMSM to improve maximum power in the field weakening region

This paper presents rib design in the rotor of IPMSM to increase maximum power in the field weakening region without variation of PM usage, conductor and size. Rib design is critical issue in the design of IPMSM due to leakage flux of permanent magnet and dominated by mechanical strength, therefore structural analysis should be conducted and minimum thickness should be selected. Rib design also affects to the inductance and saliency ratio and results in the variation of the field weakening performance and output power. With determined rib thickness, motor parameters and other motor characteristics according to rib length are presented in this paper. By redesigning rotor ribs, 10% of increased maximum power in the field weakening region is achieved. Finite element analysis (FEM) and equivalent circuit analysis are used for parameter and performance estimation, and designed motor is verified by experiments.