说明：   传统的PMSM DTC系统因为把磁链的空间均匀的分成了六个部分，并且使用了滞环控制器来控制磁链和转矩，所以不可避免的存在着较大的转矩脉动和磁链脉动等问题。在磁链处在扇区分界处时，它的增量明显不对称，所以在PMSM DTC系统设计时很有必要降低磁链在边界处的不对称性，从而达到减小转矩脉动的目的。本章在分析PMSM DTC系统存在的转矩和磁链脉动问题的基础上，深入研究了一种新型的控制方法，就是把磁链的扇区进行细分，仿真结果表明，在采用扇区细分控制策略以后，PMSM DTC能够获得良好的动态性能，转矩脉动问题也显著的减小。
(The paper analyses the direct torque control principle of permanent magnet synchronous motor in detail at the basis of describing the mathematical model of PMSM.Then,the paper analysis the principle of stator flux linkage sector Division、the effect of voltage vector in PMSM DTC system and the effect of zero voltage vector.Besides that,the paper analyses the principle of Voltage vector selection and the defect in PMSM DTC system.The simulation results show that the permanent magnet synchronous motor based on direct torque control strategy is feasible, the system has strong anti-interference ability, fast torque response, at the same time, the simulation results also show that adding zero voltage vector, the system can reduce the torque ripple and improve the steady-state performance.)