基于最大转矩控制的异步电机直接转矩弱磁控制方法

提出一种基于最大转矩控制的弱磁控制方法,用于异步电机直接转矩控制的弱磁运行,其基本思想是在弱磁阶段采用六边形磁链轨迹,使磁链给定值跟随转矩变化磁链自发削弱,转矩给定值限幅.该方法不需要精确的异步电机运行参数,能实现弱磁运行方式进入和退出的平滑过渡.在整个运行过程中将定子磁链给定值限制在设定区间,在不同的速度区段修改定子磁链给定值,不需要复杂计算.仿真结果表明:异步电机直接转矩控制系统在弱磁升速和降速过程中的运行性能得到改善；在弱磁运行到同一速度时,弱磁升速或降速过程中输出转矩小和过渡时间长的问题得到有效解决,六边形磁链和圆形磁链之间能够平滑过渡.

A novel flux-weakening scheme for direct-torque-control system of induction motor based on maximal torque control

A new control scheme for flux-weakening operation of direct-torque-control induction motor drive was proposed.Its philosophy is to adapt hexagon flux track and make the flux reference respond to the change of the torque,thus weaken the spontaneous flux and limit the torque reference.The smooth transition into and out of the flux-weakening operation mode can be realized without any work parameters of the induction motor.The stator flux value is also restricted by a setting value in the whole process.It is easy to realize the control strategy by giving the flux reference in different speed stages without complicated calculation.Simulation verifies that the application of the control strategy improves the high speed performance of direct torque control effectively.With the premise of accelerating to the same speed,the problems of small output torque and long time for speed-up or slow-down are solved remarkably,and the smoothly transition between hexagon flux track and circular flux track is also implemented.