基于自适应FIR算法的交流伺服系统前馈控制

永磁同步电机(PMSM)交流伺服控制系统中由于电子器件的开关引起相电流非正弦变化,经坐标变换得到的交直轴电流含有谐波成分,引起电流环振荡及电磁转矩脉动。在分析相电流与交直轴电流高次谐波关系,以及交直轴电流高次谐波对电磁转矩影响的基础上,提出了一种基于自适应FIR滤波器的交流伺服系统前馈控制策略,并在该方法的基础上提出了变步长因子算法,根据误差值改变步长因子,在提高滤波器收敛速度的同时减小超调。该算法与传统的一阶低通滤波器相比,相位不滞后,灵敏度更高,且系统稳定。改进后的控制策略有效地降低交直轴电流谐波,抑制电流环振荡及电磁转矩脉动,提高PMSM交流伺服控制系统稳定性及动态响应。通过仿真与试验证明了该方法的可行性。

Research on Feedforward Control of AC Servo System Based onAdaptive FIR Algorithm

In the permanent magnet synchronous motor (PMSM) AC servo control system, the phase current shows nonsinusoidal variation due to the switching of electronic devices. The direct and quadrature axis currents obtained by coordinate transformation contain abundant harmonic components, causing current loop oscillation and electromagnetic torque ripple. On the basis of analyzing the relation between the phase current and the higher harmonics of the direct and quadrature axis currents, as well as the effect of higher harmonics on the electromagnetic torque, a feedforward control strategy based on adaptive FIR filter was proposed for AC servo system. Furthermore, a variable step length factor algorithm was proposed, with which the step length factor was changed according to the error value, so as to improve the convergence speed of filter and reduce the overshoot. Compared with the traditional firstorder lowpass filter, this algorithm had no phase lag, and showed higher sensitivity and system stability. The improved control strategy was effective to reduce the direct and quadrature axis current harmonics, restrain the current loop oscillation and electromagnetic torque ripple, and improve the PMSM AC servo control system stability and dynamic response. The feasibility of this method was proved by simulation and experiment.