六相感应电机直接转矩控制的新策略

为直接控制电机的气隙磁通和电磁转矩，提出了特殊的定子电流波形.从理论上对这种特殊电流波形激励的六相感应电机内部气隙的磁场强度性能进行了分析，并推导出电磁转矩的方程式.根据所提出的直接转矩控制技术，对一个小型（2 kW）两极六相感应电机驱动系统在电流数字滞环控制下进行实验研究.实验结果表明，电磁转矩和转矩电流在MMF平衡条件下呈线性关系而与负载的大小无关.采用电流波形驱动六相感应电机的优点是气隙磁场类同于直流电机的一个方波，并且可以实现电磁转矩的直接控制，省去了繁琐复杂的派克变换和逆变换.这种转矩控制新策略也可使系统具有良好的动态性能.

Novel torque control strategy of six-phase induction machine

Special phase current waveforms in case to control directly the flux and torque of the machine were proposed. With the special phase current waveforms the performance of the six phase induction motor was evaluated through theoretical analysis. Furthermore an equation for the electromagnetic torque was derived. Based on the control method proposed the system’s performance with the direct control technique was verified by measurements on a small (2 kW) two pole, six phase induction motor drive under digital hysteresis current control. It is shown that the calculated results from theoretical derived equations are in good agreement with measured results. The results measured linear relationship between the torque and torque current show that MMF balance is maintained in the motor by the drive controller independent of the load condition.  The results also show that a square field in the air gap similar to DC machine is produced by using this special stator current waveform, and elecreomagnetic torque control can be realized without the complex Park transformation. The direct control of the torque also explains the good measured dynamic performance found for the proposed control strategy.