Two-Stage Optimal Design of Concentric Ferrite PM Layer IPMSM for Micro-EV Traction Considering Driving Characteristics

In this article, the interior permanent magnet synchronous motor (IPMSM) using ferrite permanent magnet (PM) for micro-electric vehicle (EV) traction is proposed. The characteristics of V-type IPMSM using Nd PM and a motor of the same shape using ferrite PM are analyzed when applied to micro-EV traction, the cases of power dissatisfaction with ferrite PM motor are derived, and the improvement methods are presented. Based on the improvement method, the rotor outer diameter, PM layer, and PM ratio are considered in the initial design. After the initial design, a two-stage optimization method is introduced to reduce the number of samples required. The first optimization is performed considering the power of the driving area, mechanical stiffness analysis during high-speed rotation, and low-temperature demagnetization analysis of ferrite PM. Then, the second optimization is performed considering the main operating points (MOPs) of the efficiency perspective and the MOPs of the frequency perspective through micro-EV model. Based on the design results, the possibility of a motor for micro-EV using ferrite PM is suggested by comparing the performance with the existing motor using Nd PM. Experiments are conducted on the manufactured motor, and the validity of the design results is verified by comparing the test results and FEA results.