电动机是将电能转化成机械能的主要装置，其调速性能影响着产品质量、生产效率以及电能的利用率，所以，对电机运行速度的控制是十分必要的。 直接转矩控制具有结构简单，涉及的电机参数少，动、静态性能优良等特点。但是目前直接转矩控制理论尚未发展成熟，实际运行中，转矩脉动大，开关频率不固定，低速时转矩速度跟随误差大等问题仍没得到很好的解决，所以，对直接转矩的进一步研究具有现实意义。 直接转矩控制技术采用空间矢量分析方法，在两相定子坐标系下计算、控制交流电机的转矩和磁链，根据定子磁场定向，直接跟踪定子转矩和磁链，借助于两点式调节器，通过滞环控制，选择电压矢量对逆变器的开关状态进行控制，以获得转矩的动态性能。但是，直接转矩采用滞环控制，导致转矩和磁链脉动大。同时，其依赖电机的线性模型，速度控制器采用固定数值的PI控制器输出转矩，在突加负载或速度突变时，转矩和转速的跟踪效果不理想。 针对传统直接转矩控制转矩、磁链脉动大的问题，在传统直接转矩控制的基础上，引入空间矢量调制技术，将SVM与直接转矩控制相结合。用PI控制器取代滞环控制器，以SVM模块代替开关表，在每个采样周期中求得一个能够恰好补偿当前定子磁链误差与转矩误差的参考电压矢量，由两个相邻的基本工作电压矢量及零电压矢量合成，从而达到减小磁链转矩脉动的目的。 针对突加负载或速度突变时，转速、转矩跟踪性能较差的问题，引入模糊PI控制，将传统的转速调节器中的PI控制改进为模糊PI控制，使其在全速范围内，合理选择不同的PI参数，调节系统的性能。 建立了转矩、转速、磁链闭环控制系统仿真模型，对DTC、SVM、FUZZY-SVM闭环控制进行比较。实验结果表明： SVM-DTC能减小传统DTC系统的转矩、磁链以及电流脉动，改进传统DTC系统性能。验证了相对SVM控制而言，模糊SVM控制在全速范围内响应速度更快，超调量更低，说明设计是合理的。

The motor is the main device which converts electric energy into mechanical energy. Speed governing performance of the motor affects product quality, production efficiency and utilization rate of electric energy. It is necessary to control the running speed of motor. Direct torque control has the advantage of simple structure, involved less motor parameters, and better dynamic, static performance. But at present the direct torque control theory is not yet mature, there are still some problems remain to be solved, such as large torque ripple, variable switching frequency and large following torque and speed errors at low speed. It has practical significance for further research on direct torque control. The space vector analysis method is used in direct torque control technique. The torque and flux linkage of AC motor is calculated and controlled in two phase stator coordinate. According to stator field orientation, torque and stator flux can be traced directly. Based on the two-point regulator, voltage vector is selected to control switch state of the inverter, and obtain the torque dynamic performance is obtained. However, hysteresis control results in large torque and flux ripples. At the same time, direct torque control depends on a linear model of the motor, whose speed controller uses PI controller with fixed value to output torque. Therefore，the tracking result of torque and speed are undesirable when the load or speed changes suddenly. Because of the large torque and flux linkage ripple of the traditional direct torque control, the space vector modulation technology is introduced. By using PI controller to replace the hysteresis controller and replacing the switching table by SVM module, the reference voltage vector is obtained in every sampling cycle. The reference voltage vector is synthesized from two adjacent basic working voltage vector and zero voltage vector which can exactly compensate current flux error and torque error .Therefore, this methods can achieve the purpose of reducing flux and torque ripples. By using the fuzzy PI control , the problem of the poor tracking performance of speed and torque is resolved in the sudden load or speed. The PI control of the traditional speed regulator control is improved into the fuzzy PI control, which reasonable choice of different PI parameters in the full range to adjust performance of control system. The simulation model of the torque, speed and flux closed-loop control system is established, and the performance of the closed-loop control including DTC, SVM, FUZZY-SVM is compared. The experimental result shows that the torque, flux and current ripples of traditional DTC system are reduced by SVM-DTC, and the performance of the traditional DTC system is improved. Compared with the SVM control, the speed response of the fuzzy SVM control is faster in full-speed range with lower overshoot. It can be indicated that the design is reasonable.