基于谐振数字滤波器的直驱式永磁同步电机转矩脉动抑制方法

Torque Ripple Suppression Method of Direct-drive Permanent Magnet Synchronous Motor Based on Resonant Digital Filter

由于受逆变器的非线性特性、转子永磁体磁场谐波和齿槽转矩等因素的影响,永磁同步电机定子电流中含有大量的高次谐波分量,这些谐波分量与转子永磁体磁场作用,使电机产生转矩脉动,特别在直驱系统中,转矩脉动更为严重。针对这一问题,提出一种基于谐振数字滤波器的转矩脉动抑制方法。该方法基于理想谐振控制器在谐振频率点处的增益为无穷大,可以对谐振频率点处的正弦信号实现零稳态误差跟踪控制的特点,在文中设计了一个谐振数字滤波器,并把它串联在电流环PI控制器的输出端。通过谐振控制器产生谐波电压补偿信号,抵消电流环PI控制器输出电压中的谐波分量,实现对输出电压的数字滤波,从而减小定子中的谐波电流含量,实现对转矩脉动的抑制。仿真与实验结果验证了文中所提方法的正确性和有效性。

Influenced by the nonlinear characteristics of inverter,the existence of flux harmonics of the rotor permanent magnet,cogging torque and other factors,the stator current of permanent magnet synchronous motor contains a lot of high order harmonic currents,which results in the motor generating harmonic torque ripple.The torque ripple is more serious for direct-drive system.Focused on the problem,a new control method of suppressing the torque ripple based on resonant digital filter is proposed.Because the gain of the ideal resonant controller is infinity great at the resonant frequency,zero steady state error control can be achieved for sinusoidal signal of the resonant frequency.A resonant digital controller was designed and it was connected in series with the current proportional-integral（PI） controller.A harmonic voltage compensating signal which was used to counteract harmonic components in the output voltage of the current PI controller was generated by the resonant controller,and the operation of digital filtering for output voltage signals can be realized.Therefore,the current harmonics can be decreased,and the torque ripple can also be suppressed with it.The validity and effectiveness of the proposed method are demonstrated by simulation and experimental results.