基于定子磁链滑模观测器的异步电机空间矢量调制直接转矩控制

Induction Motor Direct Torque Control Based on Stator Flux Sliding Mode Observer and Space Vector Pulse Width Modulation

针对异步电机直接转矩控制,设计了一种基于滑模控制理论的定子磁链自适应滑模观测器,它以定子电流和磁链为状态变量,利用实际电流与观测电流的误差构成滑模面,并将状态开关信号,输入到电流、磁链状态方程,对电流、磁链观测进行校正,此外通过一个由李亚普洛夫函数附加关系式完成对转子角速度的辨识。为降低系统低速稳态运行时的转矩脉动且保证瞬态运行时转矩的快速响应,在传统直接转矩控制基础上,使用占空比技术,实时计算电压矢量减小转矩误差所需的脉宽,实现对转矩的无差控制,该方法在保证系统响应速度的同时减小了系统平均转矩脉动。实验结果表明,定子磁链滑模观测器观测精度较高,速度辨识过程响应较快、精度较高,新转矩控制方法充分利用了功率器件开关频率,在低速时获得了相对圆形磁链轨迹更小的转矩脉动。

A adaptive stator flux observer based on a sliding mode control theory was designed for the induction-motor（IM） direct torque control（DTC）,in which the stator current and the stator flux were used as state variables.The error between real and observed currents was selected as sliding hyperplane,and the state control signal was inputted to the state equation to correct the stator flux and the current estimated.In addition,the motor speed was estimated by an additional relation obtained by a Lyapunov function.Finally,a duty cycle technology based on traditional DTC was introduced to reduce the torque ripple during the stable state and to guarantee fast torque response during dynamic state.The pulse width of the reference voltage vector which diminishes the error of torque is real-time calculating.So the average torque ripple is reduced and the response of the system is guaranteed.