Abstract
In this work, an optimal parameter tuning method for the PI controller is proposed to control speed and current loops of the surface mounted permanent magnet synchronous motor (SPMSM) under the field-oriented control (FOC) strategy. Furthermore, to guarantee robustness of the system to parameter variations and disturbance effect, the extended state observer (ESO) is introduced in both speed and current control loops. The performance of the PI controller tuned by the proposed optimal tuning method is compared with the PI-PI and disturbance observer-based (DOB) controllers where the parameters of the PI schemes are tuned by the Ziegler-Nichols method. Different critical testing conditions (i.e., step changes of speed and load torque, step change of load during the acceleration of the motor) are studied to compare the performances of each scheme. Simulation results have shown that the DOB controller and ESO- based PI speed controller tuned by the proposed algorithm shown almost similar peformance, whereas an ESO-based PI-PI cascaded control scheme with optimal parameters had superior characteristics compared to other controllers in the study. The worst performance among the studied control schemes was shown by the conventional PI - PI cascaded control with largest speed drop and longest time to reach a steady state. All the control algorithms are implemented in MATLAB/Simulink environment.