Antiwindup design for the speed loop PI controller of a PMSM servo system

A novel antiwindup (AW) strategy for a proportional-integral (PI) regulator based on the back-calculation method is presented. The proposed method will calculate the gain of the back-calculation based on the input and output status of the PI regulator without the requirement of motor parameters, such as the inertial and torque-current coefficient, and the back-calculation gain will vary with the speed command in order to obtain the optimal dynamic performance. The proposed method avoids the problem caused by the fixed back-calculation gain in the classical AW strategy, and prevents the system from untimely saturation withdrawing or an unexpected overshoot due to the inappropriate backcalculation gain, respectively. The proposed AW strategy is compared with the classical AW design by simulation and experiment on an application platform of a permanent magnet synchronous motor servo system. A PI controller with the proposed AW design will decrease the overshoot with a small settling time of the system s step-response, which can be observed obviously in wide dynamic variation. It reduces the difficulty of the parameter tuning for the PI controller.