基于预测控制的直接转矩控制系统的研究

Research on direct torque control of induction motor based on predictive control

针对异步电动机直接转矩控制(DTC)系统在低速时由于开关频率不稳定而引起转矩脉动较大的缺点,提出了一种预测控制方法。该方法根据转矩和定子磁链的误差来确定应该施加的参考电压矢量,最后利用空间矢量脉宽调制(SVPWM)方法来合成该矢量,这样即保证了逆变器的开关频率恒定,从而大大降低转矩脉动。仿真结果表明,在低速下定子磁链轨迹近似为圆,转矩脉动不明显。

A new predictive control strategy of direct torque control（DTC） was proposed to reduce the large torque ripple of induction motor caused by the instability of switch frequency due to conventional direct torque control at low speeds. Reference voltage space vector can be determined by calculating the errors of the flux and torque in tenrrs of the predictive strategy. The vector is then synthesized by a SVPWM（space vector pulse width modulation） algorithm to keep a constant switch frequency. The simulation shows that the control method can lessen the torque ripple and maintain the waveform of stator flux nearly round.