摘  要

随着电力电子和计算机等技术的发展，交流电机的优势愈加凸显，并因体积小，质量轻和效率高等优点广泛应用在可靠性要求高的场合。直接转矩控制因简单易于实现，转矩响应快且鲁棒性强，已广泛应用于交流电机控制中。

三相交流电动机在电力拖动自动控制系统领域中有广泛应用，传统的交流电动机双闭环调速系统多采用结构简单、性能稳定的带限幅的PI调节控制器，但由于电机的参数变化与非线性特性，使得PI控制器的参数往往难以达到最优状态，而且参数的一成不变难以跟随现场的动态变化。

但直接转矩控制中因开关频率不稳定，存在磁链控制不对称，转矩脉动大等问题，因此本文运用MATLAB这一高性能仿真软件构建了一个交流电机直接转矩控制系统，采用三点式转矩调节方法优化空间电压矢量的选择，给出了较为详细的设计步骤。利用MATLAB Sim Power Systems控制仿真，对传统的双闭环交流电机调速系统进行改造，对于我们提高交流电动机双闭环调速系统的控制性能有重要的指导意义。仿真结果表明该控制方法较传统的直接转矩控制方法具有更好的动态，稳态性能，为实际系统设计提供了依据。

关键字：三相交流电动机；数学模型；MATLAB仿真；直接转矩；调速控制

Abstract

With the development of power electronics and computer technology, the advantages of AC motor become more and more prominent, and are widely used in high reliability requirements because of its small size, light weight and high efficiency. Direct torque control is widely used in AC motor control because of its simplicity and easy implementation, fast torque response and strong robustness.

The three-phase AC motor is widely used in the field of electric drive automatic control system. The traditional AC motor double closed-loop speed regulation system adopts PI control controller with limited amplitude with simple structure and stable performance. However, due to the change of motor parameters and nonlinear characteristics, the parameters of PI controller are difficult to reach the optimal state, and the parameters are difficult to follow the dynamic changes in the field.

However, due to the unstable switching frequency, asymmetric flux control and large torque ripple in direct torque control, a direct torque control system for AC motor is constructed by using MATLAB high performance simulation software. The three-point torque regulation method is used to optimize the selection of space voltage vector and the detailed design steps are given. By using MATLAB Sim Power Systems control simulation, the traditional double closed loop AC motor speed regulation system is reformed, which has important guiding significance for us to improve the control performance of AC motor double closed loop speed regulation system. The simulation results show that the control method has better dynamic and steady performance than the traditional direct torque control method, which provides the basis for the actual system design.

Keywords: three-phase AC motor; mathematical model; MATLAB simulation; direct torque; speed control