PWM开关频率对转子损耗和温升影响探究

Influence of PWM Switching Frequency on Rotor Loss and Temperature Rise

永磁电机转子损耗及温升分析对电机性能与安全非常重要。永磁电机转子损耗主要是由谐波引起的,且脉宽调制(Pulse Width Modulation,PWM)供电下输入电流谐波对损耗影响很大。因此,探究PWM供电对转子损耗和温升影响探究可以为PWM开关频率的选取提供重要参考。为实现上述目的,首先建立了场-路耦合的电机有限元仿真模型,获取了不同开关频率下转子损耗的变化情况。然后,建立了磁-热耦合仿真模型,获取了多个工作点不同开关频率下的转子温升,最终结合电机性能需求和逆变器成本选择合适的开关频率,可以为电机及其控制器设计提供重要参考。

Considering that performance of magnets in PMSM rotors are significantly affected by temperature and the risk of demagnetization under high temperature,analysis of rotor loss and temperature rise are critical to motor performance and safety.The rotor loss is mainly caused by harmonics.The input current harmonic under the Pulse Width Modulation(PWM)has a great influence on the loss,as well as the temperature rise.Studying the influence of PWM power supply on rotor loss and temperature rise can provide an important reference for the selection of PWM switching frequency.This paper proposed a method to select the appropriate switching frequency.Firstly the field-circuit coupled finite element simulation model was established and the variation of rotor loss under different switching frequencies was obtained.Then,a magnetic-thermal coupling simulation model was established and the temperature rise of the rotor at different switching frequencies was obtained.Finally,considering the performance requirements of the motor and the inverter cost,the proposed method select the appropriate switching frequency,which can provide an important reference for the motor and its controller design.