Research Of Electromagnetic Vibration And Electromagnetic Noise In High-Torque Low-Speed Permanent Magnent Synchronous Wheel Motor

Permanent magnet synchronous motor (PMSM) becomes main alternative for wheel drive system in Electric Vehicle (EV) because of its characteristics of low torque pulsation, high efficiency and high torque density. To measure the performance of the motor, and even the performance of wheel drive system, we have to take the level of vibration and noise into account, because it is an important indicator. Within the vibration and noise in motor, the electromagnetic part plays a main role. Therefore, it is of great significance to study the electromagnetic vibration and noise in permanent magnet synchronous wheel motor (PMSWM). This paper is analyzed around four aspects.Firstly, the author analyzes the electromagnetic design for low-speed and high-torque permanent magnet synchronous wheel motors. According to the performance parameter and technical requirements, the electromagnetic design of the motor is discussed from rotor structure, pole-slot combination and pole arc coefficients. The no-load, rated torque load and operating performance in three kinds of built-in rotor structure has been analyzed by the means of simulation, which is contrasted to choose the best plan.Secondly, the natural frequency of the stator in PMSWM is analyzed. The natural frequency is calculated by means of analysis. The stator and components of PMSWM are modeled and simulated with ANSYS, and the influence of cover and case to prototype is studied by means of mode analysis.Thirdly, electromagnetic vibration and noise in PMSWM are analyzed. Based on the mechanism of electromagnetic force wave, the force number and frequency of the electromagnetic wave have been deduced, which the inner face of stator teeth suffer from in 50kW wheel motor. Radial flux densities and electromagnetic force wave of three kinds of rotor structure under no-load are calculated with Maxwell analysis soft, and their distribution between radial and tangential direction are analyzed. The displacement of electromagnetic vibration in three kinds of motors has been calculated, and the noise level of electromagnetic noise also has been calculated.At last, the natural modal, electromagnetic vibration and electromagnetic noise are analyzed by the means of experimental method. The natural frequency is tested by the experiments. It is educated to design and manufacture motor to avoid resonating by the experiment results. The waves of vibration acceleration on radial and tangential direction at the same speed are tested in the experiment. The proportion of electromagnetic noise and mechanical noise in the motor noise is ascertained by the method of sudden cutting-down supply.