On-line estimation of permanent magnet flux linkage ripple for PMSM based on a Kalman filter

In order to get good control performance in permanent magnet synchronous motor (PMSM) control fields, the accurate permanent magnet flux linkage (rotor flux linkage) value is needed. For stator flux estimation and full order or reduced order observer, the rotor flux linkage is treated as a known and constant parameter. But in applications, the rotor flux linkage can vary in a wide range. In this paper, a rotor flux linkage observer based on Kalman filter is presented. After rearranging the equation of interior permanent magnet synchronous motor (IPMSM), a new set of variables is defined. By choosing the new set of variables and the rotor flux linkage as state variables, a three-order Kalman filter is constructed. For surface mounted PMSM (SPMSM), by substituting L_d = L_q to the proposed Kalman filter, the rotor flux linkage of SPMSM can be observed, too. The performance of the proposed observer is verified by simulation and experiments. Both the simulation results and experimental results show that the Kalman filter estimates the rotor flux linkage accurately