采用定子电阻辨识和无速度传感器的异步电机直接转矩控制模糊系统

为解决异步电动机直接转矩控制(direct torque control,DTC)中低速运行时定子电阻变化对系统性能影响较大的问题,提出了一种基于定子电阻辨识和无速度传感器的异步电机直接转矩控制模糊系统。其中定子电阻采用模糊神经网络进行辨识;电机转速采用基于转子磁链的模型参考自适应系统(model reference adaptive sys-tem,MRAS)法进行估计;同时采用三输入单输出的模糊控制器调节脉冲宽度调制(pulse width modulation,PWM)信号占空比的异步电动机直接转矩控制的策略,三输入变量为转矩误差、磁链幅值误差和磁通角。此策略即在传统异步电动机直接转矩控制的基础上,用模糊控制器代替传统DTC中的滞环比较器和空间电压矢量状态选择器来细分控制规则,最后控制逆变器的开关,以减小低速时转矩和磁链脉动,提高系统转矩响应速度。仿真结果表明该系统可减小转矩和磁链脉动,提高系统的鲁棒性和自适应性,改善系统的动、静态品质。

Direct Torque Control Fuzzy System of Induction Motor Using Stator Resistance Identification and Speed Sensorless

To reduce the effect of stator resistance changing with the low-speed performance in direct torque control(DTC) of induction motor on system performance,we proposed a DTC fuzzy system of induction motor based on stator resistance identification and speed sensorless.In this system,the stator resistance was identified by fuzzy neural network;the motor speed was estimated by model reference adaptive system(MRAS) method based on rotor flux;and the duty cycle of pulse-width modulation(PWM) signal for DTC strategy of induction motor was adjusted by three-input single-output fuzzy controller.The three-dimensional input variables were torque error,flux magnitude error,and flux angle.That was,on the basis of the traditional DTC of induction motor,the comparator of hysteresis and the state selector of space voltage vector in the traditional DTC were replaced by the fuzzy controller.The fuzzy controller was used in the subdivisions of control rules,and was used to adjust the switching states of inverter,so as to reduce the ripple of torque and flux at low speed and improve the response speed of system torque.The simulation results show that the system can reduce torque and flux ripple,enhance robustness and adaptability of system,and improve dynamic and static qualities of the system.