基于对称电压矢量组的直接转矩控制

Direct Torque Control Based on Symmetrical Voltage Vectors Combination

提出了一种新型的直接转矩控制策略和定子磁链观测误差校验方法。通过分析SPWM的特点,设计出基于对称电压矢量组的调制方法,并探讨了采用此方法时三相桥式电压型逆变器的电压输出能力。该调制方法获得方向任意且大小可控的等效电压矢量,以此控制定子磁链的幅值和旋转速度,从而达到对输出电磁转矩的有效控制,并获得恒定的器件开关频率。利用电压矢量组所具有的对称性,对积分获得的交流电动机磁链幅值和位置角的误差进行校正。该方法可以明显减少感应电动机定子磁链、电磁转矩和电流的波动,而转矩的快速响应仍能保持。具有鲁棒性强、开关频率恒定的优点。仿真结果验证了该方法的有效性。

A new approach to direct torque control （DTC） and the correction for the estimated stator flux linkage are presented, through analyzing the characteristic of SPWM, a symmetrical voltage vector modulation technique is presented, related output capability of the three-phase bridge voltage source inverter is discussed. Amplitude and instantaneous position angle of the stator flux linkage can be controlled by a equivalent symmetrical voltage vector of arbitrary direction and controllable magnitude, thereby, expectational torque will be achieved. The scheme may be regarded as a development of DTC scheme aimed at achieving a constant switching frequency operation. Owe to the symmetry of the vector combination, the stator flux steady-state error of a pure integrator estimator technique is reduced. Simulation test results is presented, which show that the presented method can efficiently solve the problem of torque-current and stator flux ripple, provides high performance dynamic characteristics and robustness with constant switching frequency.