异步电动机无速度传感器直接转矩控制系统的研究

【作者】 肖岸文；

【导师】 佘致廷； 周玲慧；

【作者基本信息】 湖南大学 ， 控制工程， 2003， 硕士

【摘要】 直接转矩控制技术是上世纪八十年代中期发展起来的新技术。它是继矢量控制技术之后，与之并行发展的一种新型的高性能的交流调速传动的控制技术。本论文研究了异步电动机的数学模型，介绍了直接转矩控制的基本原理，并根据传统直接转矩控制存在的缺点以及对电动机调速性能的要求，改变对定子磁链的调节方式，使定子磁链轨迹近似为一圆形。传统的直接转矩控制采用两点式转矩调节，这种调节方式在电机低速或转速突降时，会使零电压矢量所加的时间较长，这样会导致磁链严重畸变，甚至降为零，从而使转矩也降为零，调速时间较长，系统跟踪性能差。为此，本论文提出三点式转矩调节，这样当电机低速运转或给定转速突降时，不是加零电压矢量，而是加反方向的电压矢量，使定子磁链与转子磁链之间的夹角迅速减小，从而使电磁转矩也迅速减小，大大减小了调速时间，同时磁链值仍然保持基本恒定，输出比较稳定的电磁转矩，这在电机制动过程中非常有用。另外，本文还提出了一种用模糊控制器来取代传统的施密特触发器的方法。电压矢量的选择依赖于电磁转矩偏差、定子磁链偏差和磁链位置，用模糊控制器取代施密特触发器是基于容差大小本身就是一个模糊的语言变量，如果把磁链和转矩的容差分级，并以此作为选择电压矢量的依据，那么系统性能会得到改善。 无速度传感器转速估算是现代交流传动研究中的一个重要方向，本文探讨了几种主要的转速估计方法，着重分析了基于模型参考自适应的速度辩识算法。 本论文利用Matlab／Simulink软件对以上各种方法都进行了仿真，构建了采用三点式转矩调节的圆形磁链轨迹直接转矩控制系统仿真图、采用模糊控制器的直接转矩控制系统仿真图及采用无速度传感器的直接转矩控制系统仿真图，从仿真结果可以看出，以上这几种方法都是有效可行的，与理论分析是一致的。 本文最后以Intel80c196单片机为核心来设计直接转矩控制系统，这种控制系统算法简单，设计先进，功能较强，具有开发应用价值。更多还原

【Abstract】 Direct Torque Control (DTC) of induction motors, which has been developed in the recent decade, is a powerful control method for motor drives. Following the vector control-technique, the quick development of DTC makes itself a new high performance AC driving technique paralleling to the vector control. In this thesis the author makes a study of asynchronous motor model and deals in details with the basic principle of direct torque control. According to the faults of traditional direct torque control and the requirement of an induction motor’s control strategy, the author changes the method of regulating stator flux to make its path approximate to a circle as possible as could and put forward a new way to use a three-value torque regulator. Traditional direct torque control uses two value torque regulator which makes zero voltage vector work long and make flux shape bad seriously and makes response time long when the speed of induction motor is very low or drops down quickly. In order to solve this problem the thesis puts forward a new way to use three-value torque regulator, when the motor speed is very low or drops down quickly, the contrary voltage vector is used instead of zero voltage vector and the between the stator flux and rotor flux is reduced quickly so that torque is reduced quickly and response time becomes shorter. Moreover, stator flux can keep round, This is very useful in braking control.Moreover, the thesis puts forward the strategy that fuzzy controller replaces Smith flip-flop. Based on the tolerance of Smith flip-flop is a fuzzy variable, fuzzy controller can replace Smith flip-flop The performance of this system can be improved if the tolerance of flux and torque is graded and voltage vector can be elected by this.The speed estimation without speed sensor is an important trend of modern AC drive. This thesis has probed several primary methods of speed estimation and analyzed emphatically the method of speed estimate based on model reference adaptive system.SIMULINK is a applying tool box of MATLAB and can be used for constituting model, simulation and analyzing. This thesis constitutes DTS simulations with three-value torque conditioner and fuzzy regulator and speed sensorless technology. The simulation results prove that above methods are feasibility.At last the thesis introduces the design method of control system with Intel 80cl96MC. This control method has simple counting and strong function and great developing value.更多还原