Two-Step Optimum Design Process of PMSM to Improve Driving Efficiency and Harmonics of Lightweight Electric Vehicle

Urban lightweight electric vehicles (EVs) for personal mobility have the advantage of being convenient and economical. Vehicles with low vibrations and high energy efficiency are suitable for use as urban electric vehicles. The torque ripple of the motor that induces the vibration of the EV can be improved by reducing the harmonics of the magnetic flux density. The energy efficiency of an EV can be improved by increasing the efficiency at the main operating points (MOPs) by considering the driving cycle. Through the proposed design process, optimization was performed to improve the harmonic characteristics of a high-efficiency lightweight EV with a stator chamfer and rotor notch structure. The harmonics of the magnetic flux density due to the teeth and slots are improved through the stator chamfer, and the fundamental component of the magnetic flux density is increased through the rotor notch structure. The optimum model designed through the proposed design method has improved the efficiency at the MOPs and harmonic characteristics.