一种基于无功功率的异步电机矢量控制转子磁场准确定向方法

A NOVEL ROTOR FLUX ORIENTED SCHEME OF INDUCTION MOTOR BASED ON REACTIVE POWER

当转子磁场定向的异步电机矢量控制系统工作在高频弱磁区时,由于电机参数变化等多种因素影响,导致磁场定向不准,甚至危及电机可靠运行。为了保证磁场定向的准确,提出一种根据无功功率对转子磁场观测位置进行校正的控制方法,即以无功功率闭环来校正转子磁链的观测位置。同时,采用给定d轴电流的方法来保证系统不受磁链观测幅值不准的影响。实验证明,该方法改善了弱磁高速区的控制性能,使功率、电压均基本保持恒定,大大提高了矢量控制系统对电机参数特别是转子时间常数的鲁棒性。

It is difficult to make the reference frame aligned with the rotor flux vector in an induction motor rotor flux oriented vector control system especially in the region of high frequency and flux-weakening because of the effects of parameter mismatch etc, which even causes the drive system can not operate normally. In order to realize accurate rotor flux orientation, a novel control strategy of compensating rotor flux position observed in terms of reactive power is presented in this paper. A closed-loop controller in terms of reactive power is adopted to correct the calculated position angle of rotor flux. Moreover, in order to eliminate the influence of inaccurate flux amplitude observed, the d-axis current reference is set according to the motor characteristic of exciting current via speed. The experiments show that the performance in flux-weakening region is improved observably, where the power and voltage remains constant. So the robustness of the control system to the motor parameters, especially to the rotor time constant, is raised highly.