A nonlinear current control for field oriented controlled permanent magnet synchronous machine drives

Conventional PI is designed based on linear control theory, but the permanent magnet synchronous machine (PMSM) model is nonlinear. The integral direction of conventional PI is determined by the sign of error, which always results in integrator-windup when large set-point steps are set, so it is unable to response fast without overshoot. In order to improve the current response performance of PMSM, by researching PI and PD, a new nonlinear current control strategy was proposed. It regulated effectively the integral direction according to the sign of PD´s output. The experimental results demonstrate that the control algorithm can improve the dynamic and steady performance of the system.