永磁同步电机直接转矩控制系统转矩调节新方法

从开关频率优化和电压空间矢量合理选择2个方面提出了1种新的转矩调节方法。通过逆变器开关频率PI调节得到转矩滞环比较器的滞环宽度值,在充分利用功率器件开关频率的同时,不仅克服了圆形磁链轨迹对功率器件高开关频率要求的缺陷,而且克服了在转速变化过程中采用固定滞环宽度值带来的功率器件开关频率波动范围大且低速转矩调节性能下降的缺陷。针对零电压空间矢量的特点,为降低系统低速稳态运行时的转矩脉动且保证瞬态运行时转矩的快速响应,提出了在低速稳态运行时选用零电压空间矢量减小转矩、在低速瞬态运行时选用有效电压空间矢量来减小转矩的转矩调节方法。该方法在保证系统响应速度的同时减小了系统平均转矩脉动。实验结果表明新的转矩调节方法不仅能充分利用功率器件的开关频率,而且在低速时由于开关频率的提高反而获得了相对圆形磁链轨迹更小的转矩脉动。

A New Torque Adjustment Method of Permanent Magnet Synchronous Machines Direct Torque Control System

In order to reduce the high frequency caused by round flux locus and to solve the contradiction between switching frequency and torque pulse caused by the fixed hysteresis band width, a method of achieving hysteresis bandwidth of the torque hysteresis controller by using the PI adjusting method of power device switching frequency has been proposed, which not only makes full use of the frequency of power device but also overcomes the shortcoming of high frequency caused by round flux locus and the big pulsation of switching frequency changing with speed. In the low speed region of PMSM, a new voltage space vector selection method has been introduced in order to reduce the torque ripple during stable state and guarantee fast torque response during dynamic state, that is, during the low speed stable state, zero voltage space vector is chose to reduce the torque and during the dynamic state of low speed, non-zero voltage space vector is chose to reduce the torque, by doing so, the average torque pulse is reduced and the response of the system is guaranteed.