Application of State Feedback Controller with Feedforward for velocity ripples reduction of PMSM drive at low speed operation

This paper proposes a relatively simple and effective method for velocity ripples reduction of a Permanent Magnet Synchronous Motor (PMSM) using a State Feedback Controller (SFC) with feedforward path coupled with the estimated load torque. A linearized state-space mathematical model of the plant was introduced using a classical decoupling method. To ensure good dynamical properties of the system an a posteriori Model Predictive Approach Constraints (MPAC) method for drive current limitation was introduced. The designed compensation path is based on a disturbance observer based on extended Kalman filter algorithm. The estimated disturbance signal contains an periodic component caused by the presence of cogging effect phenomenon, pulsating torque and current measurement errors. A detailed harmonic analysis was performed for the measured and estimated variables i.e. angular velocity, estimated disturbance, q -axis voltage and current components. Experimental results show efficient reduction of velocity ripple at low speed operation.