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


Abstract: 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 back-calculation 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.

Keywords: PMSM, antiwindup, integration saturation, PI controller

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