改善异步电动机低速性能的直接转矩控制方法

A direct torque control method for asynchronous motor to improve low speed performance

传统六边形磁链异步电动机直接转矩控制方法存在磁链脉动大、逆变器死区时间的问题。逆变器死区的存在会产生电流畸变,尤其在低速时,转矩脉动将随着磁链脉动和逆变器死区而增大。提出一种利用硬件和软件改进控制系统的方法,通过三相和两相定子电压的轮流导通,消除逆变器死区时间,并构造12个电压矢量,形成逼近的圆形磁链轨迹,减小磁链的脉动,从而有效地减小低速乃至整个调速范围的转矩脉动。对该方法建立了系统仿真模型并得出了仿真结果。

Traditional6-sided polygon flux torque control system for asynchronous motor has two shortcomings,such as flux pulsation,difficulties in eliminating dead time of inverter.The dead time of inverter can bring the current deformed,especially at low speed.Torque pulsation will increase with the primary flux pulsation and existence of dead time.A new improved control system in both hardware and software is proposed,which can effectively eliminate dead time of inverter through introducing three-phrase and two-phrase primary voltages in turn,build twelve primary space voltage vectors to form approximate circle flux trajectory,reduce flux pulsation as well as torque pulsation in the case of low speed and the whole timing area.The simulation results are presented through building the simulation model.