Reduced-order control of permanent magnet synchronous motors

This study presents simple and effective high performance tracking controllers for permanent magnet synchronous motors (PMSM). A reduced-order model is derived from the singular perturbation analysis of the PMSM model by taking advantage of the two-time-scale property of small electrical machines. Controller designs based on this reduced model are simple and do not need to measure the current signals for feedback purposes because the model applies a set of second-order nonlinear dynamic equations that contain only mechanical variables. The steady-state current response can still be controlled indirectly to achieve near-minimum power dissipation, even though current signals are not measured. Moreover, the stability of the reduced system, as well as that of the original full system under control, is also studied herein. Experimental results demonstrate that the controllers developed in this study are capable of achieving high performance position and velocity tracking control.