非理想反电动势无刷直流电机的转矩脉动抑制仿真研究

Simulation and research on torque ripple reduction for BLDC motors with non-ideal back EMF waveforms

在伺服系统中要求电机转速平稳,抑制转矩脉动是实现转矩平稳的关键,而非理想反电势会引起较大转矩脉动。为了有效平滑无刷直流电机转矩,分析了两种不同的方法:根据定子电流和反电势与转矩表达式的关系,对于一台给定的电机,只要其反电势一定,通过优化定子电流就可以消除主要的转矩谐波分量,从而达到减小转矩波动的目的;通过坐标变换在Id=0时求解产生恒定电磁转矩所需的q轴电流,并在dq坐标系下通过矢量控制对q轴参考电流进行跟踪实现转矩脉动抑制。利用MATLAB/SIMULINK仿真平台建立系统的仿真模型,对系统模型进行仿真和分析并比较了这两种方法的特点,为实际电机的控制提供了研究方向。

Torque-ripple control of the brushless DC motor has been the main issue of the servo drive systems in which the speed fluctuation, vibration, and acoustic noise should be minimized. Non-ideal back EMF （electromagnetic force ）usually induces more distinct torque ripple rather than commutation torque. Two drive methods are analyzed to smooth the torque for BLDC （blushless DC） motors with non-ideal back EMF waveforms. The torque expression is derived in terms of the stator current and EMF. For a given machine, the back EMF harmonics can be determined, and it is possible to calculate an optimum feed current waveform that cancels out most significant torque harmonics to produce smooth torque. The Iq for a constant torque to produce is calculated through coordinate transformation when Id=0, and the reference Iq is tracked by vector control in the dqO frame. The simulation model of system is build, simulated and analyzed in Matlab/Simulink. The simulation results show that two control technique which have their advantages and drawbacks can effectively minimize the torque ripple caused by distortion of the back-EMF, and offer a way for designing and controlling actual motors.