三相四开关逆变器供电的IPMSM直接转矩控制系统建模与分析

Modeling and Analysis of the Direct Torque Control System for IPMSM Fed by Three-Phase Four-Switch Inverter

为获得较高的转矩响应速度和较低的转矩脉动,将基于比例-积分控制器和空间矢量调制的直接转矩控制(PI-SVM DTC)引入到由三相四开关逆变器供电的凸极式永磁同步电机(IPMSM)驱动系统中。鉴于电机的强耦合性,同时为便于分析其定子磁链环,建立了IPMSM在静止坐标系下以定子磁链为状态变量的状态空间模型。为改善系统的稳态性能,构建无差拍全阶状态观测器,实现对定子磁链的闭环观测。揭示了传统定子磁链环极点放置位置存在的问题,并利用一种简单的方法对定子磁链环极点位置进行优化。对PI-SVM DTC的转矩环进行建模分析,为PI控制器的设计提供依据。另外,为抑制三相四开关逆变器直流母线中性点电压偏移,根据其偏移量生成合适的补偿量,并将其添加到定子磁链控制环中。实验结果验证了该模型的有效性。

The proportional-integral controller coupled with space vector modulation based direct torque control （PI-SVM DTC） scheme was introduced in this paper to the three-phase four-switch inverter fed interior permanent magnet synchronous motor （IPMSM） drive system to obtain a higher torque dynamic response and a lower torque ripple output. Considering the strong coupling of IPMSM and the convenience of analyzing the stator flux control loop, the state-space model for IPMSM in static coordinate was established, which chose the stator flux as the state variables. To improve the steady-state performance, a deadbeat full-order state observer was built to realize a closed-loop estimation of stator flux. The problems caused by the conventional pole placement of the stator flux control loop were revealed, and a simple method was proposed to optimize the pole positions of the stator flux loop. Then, the model of the torque control loop was also created. Additionally, to inhibit the deviation of the neutral point voltage of DC-link, a compensation was produced according to the deviation, and added into the stator flux control loop. Experimental results have validated the effectiveness of the proposed model for PI-SVM DTC.