An Improved Speed Controller for PMSM Drive with Unbalanced Load Using Load Torque Observer

In order to overcome disturbance effects as load torque variations in Permanent Magnet Synchronous Motor (PMSM) of washing machines, an improved controller with feed forward compensation is presented in this paper. A few load torque observer techniques have been studied and combined with several sensorless control techniques. The observed torque is used as feedforward in q-axis current PI controller to compensate the output of speed PI controller. Simulation and experimental results show that in an operating system with disturbances as washing machines, PI controller response time can be improved by adopting an accurate feedforward scheme.