基于空间矢量理论异步电动机起动过程的控制

Control of Asynchronous Motor Starting Process Based on Space Vector Theory

为了提高异步电动机的起动性能,对异步电动机的起动过程进行了研究.在空间矢量理论的基础上,导出以定子电流矢量、转子磁链矢量为核心变量的动态方程.通过仿真分析和动态方程理论分析,揭示了异步电动机在非受控状态下全压起动时转子转速、电磁转矩、定子电流、转子磁链的变化过程,指出异步电动机起动时起动电流大而起动转矩并不大的主要原因在于起动时磁场建立过程的不平稳性.以此为基础,提出采用预励磁及全过程控制定子电流矢量转速和幅值的方法,使转子磁链矢量平稳建立且与定子电流矢量同步旋转.最后仿真和实验结果表明该方法可在大大减小起动电流幅值的情况下达到全压起动同样的效果,起动性能明显提高.

To further study asynchronous motor starting process and enhance its starting performance, on the basis of space vector theory, dynamic equations were deduced in which stator current vector, rotor flux linkage vector were core variables. Through simulation and the dynamic equations, changes of rotor speed, electromagnetic torque, stator current, rotor flux linkage of the asynchronous motor in the full voltage starting process were revealed. The instability of the magnetic field establishment being the main cause of larger current but lower torque in starting process was pointed out. The method of pre-excitation and controlling speed and amplitude of the stator current vector in whole starting process was put forward, and it could make the rotor flux linkage vector be established smoothly and rotate with the stator current vector synchronously. The simulation and experiment results show that it could greatly reduce the amplitude of starting current to achieve the same effect as the full voltage non-controlled starting. Starting performance improves significantly.