高精度永磁同步直线伺服系统中的电流测量

采用磁场定向控制的永磁交流同步直线伺服系统中,电流反馈的精确度将直接影响电流环及整个系统调节性能。分析了采用空间矢量脉宽调制(SVPWM)电压型逆变器驱动的直线交流电机绕组中由于矢量切换以及电缆与电机阻抗不匹配引起的谐波电流及其对电流采样的影响。通过选择采样点来抑制SVPWM周期谐波的影响,通过在电流传感器后引入二阶滤波器及对其引起的时间滞后进行补偿,有效地提高了电流检测的精度。实验结果表明,该方法切实可行,为进一步提升伺服系统的性能奠定了基础。

Current measurements in high precision permanent magnet synchronous linear motor servo systems

Current measuring fidelity in permanent magnet synchronous linear motor servo systems directly influences the performance of the current loop and the whole system when field oriented control is used.This paper presents an analysis of the harmonic components in the motor phase current,which are caused by switching of the vector and mismatch of the impedance of the cable and the motor.These harmonics influence the current measurement when the motor is driven by a space vector pulse width modulation(SVPWM) voltage inverter.The current measurement accuracy is significantly improved by selecting an appropriate sampling point to suppress the SVPWM period harmonics,by introducing a second order filter after the current sensor and by a delay time compensating for the filter.Experimental results verify the method which provides a basis for performance improvements of servo systems.