A Deadbeat PI Controller With Modified Feedforward for PMSM Under Low Carrier Ratio
Zhijian Zhang, Long Jing, Xuezhi Wu, Wenzheng Xu, Jingdou Liu, Guangqiang Lyu, Fan Zi-lian
Abstract
When the permanent magnet synchronous motor (PMSM) operates at low carrier ratio, the decoupling capability and dynamic performance of the proportional-integral (PI) controller are limited by the digitization delay. In this paper, a deadbeat PI controller is proposed by modified the feedforward. With the modified feedforward, the open-loop transfer function can eliminate imaginary components. Thereby the full decoupling of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula> is realized. At the same time, the controller also has full control over the location of the closed-loop poles, indicating that it can have a deadbeat response for the command tracking. For the disturbance rejection, the controller allows us to select the speed with which the controller can cancel the effect of a disturbance. Further considering that the motor parameters are inaccurate, by designing the controller coefficients with the maximum value of the closed-loop poles, the current-loop can ensure the dynamic performance and harmonic suppression ability. Finally, the effectiveness of the proposed controller is verified by the simulations and experiments.