基于固定合成矢量的三电平异步电机直接转矩控制

DTC Algorithm of Induction Motors Fed by Three-level Inverter Based on Fixed Synthesizing Vector

针对传统的具有中点电位平衡功能的三电平固定合成矢量异步电机直接转矩控制(direct torque control,DTC)方法会引起较大的定子磁链和转矩纹波的缺点,该文改进固定合成矢量的合成方式,提出了适用于高性能三电平异步DTC系统的"24矢量"法和"24矢量+变调制比"法。从磁链、转矩控制性能的角度出发,分析了其对电机性能的改善。这两种方法物理概念清晰,结构简单,易于实现,同时还保留了传统固定合成矢量方法的优点。实验结果证明了控制方法的正确性和可行性。

The traditional three-level fixed synthesizing vectors induction motors direct torque control （DTC） algorithm with neutral-point balancing control ability may causes high amplitude ripples of stator flux linkage and torque. To solve this problem, the paper modifies the synthesizing technique, proposes ＂24 vectors＂ method and ＂24 vectors ＋ alter modulation index＂ method, which are suitable for high performance DTC system fed by three-level inverters. From the standpoint of flux and torque control effect, the improvements of motor performance by the proposed schemes are analyzed. The methods have some merits, such as vivid physical concept, simple construction, easy implementation. Besides, the merits of the traditional fixed synthesizing vectors DTC method are preserved. The experimental results verify the correctness and feasibility of the schemes.