A gain-scheduled multivariable LQR controller for permanent magnet synchronous motor

The paper presents a gain-scheduled LQR control system for a nonlinear model of permanent magnet synchronous motor (PMSM). The most popular cascade FOC (Field Oriented Control) structure including a few single-loop PI control systems is replaced with a single multivariable state feedback controller. Due to a nonlinear nature of the PMSM dynamics equations the developed gain-scheduled controller is tuned in relation to the changeable operating conditions of the motor. In order to ensure zero steady-state speed error the system synthesis is carried out by means of the LQ optimal control method with state vector augmentation. The presented simulation results show that the use of gain-scheduled controller may improve control quality.