基于弱磁控制的EPS模式切换中转矩波动的抑制

The Suppression of Torque Fluctuation in Mode Switching of EPS Based on Flux-weakening Control

针对电动助力转向系统(EPS)用永磁同步电机在i_d=0控制与弱磁控制相互切换的过程中转矩波动对系统性能的影响,设计了负载转矩观测器,对速度环中的弱磁控制模式输出的转矩进行补偿;并在两种模式切换时加入了转矩平滑切换模块,解决了切换过程中由于转矩突变带来的操纵转矩波动问题。仿真与试验结果表明,通过负载转矩观测器进行负载前馈补偿,使系统对负载扰动有很强的鲁棒性;转矩平滑切换模块对工作模式切换过程中产生的操纵转矩波动有很好的抑制作用,改善了驾驶员操纵沉重和转矩波动等不良手感。

In view of the effects of the torque fluctuation on the performance of electric power steering system in the process of switching between i_d=0 control and flux-weakening control in permanent magnet synchronous motor, a load torque observer is designed to compensate the output torque of flux-weakening control in speed loop, and a torque smooth switching module is added during mode switching, so the problem of manipulation torque fluctuation caused by the abrupt change of torque in mode switching process is solved. The results of both simulation and test show that through the load feed-forward compensation by load torque observer, the robustness of system to load disturbances is enhanced, and the torque smooth switching module added well suppress the fluctuation of manipulation torque in mode switching process, so the hand feeling of driver on the heavy turning of steering wheel and torque fluctuation is improved.