Dynamic Permanent Magnet Flux Estimation of Permanent Magnet Synchronous Machines

This paper deals with rotor flux estimation in permanent magnet synchronous motor(PMSM). In most application, the rotor flux linkage is treated as a known constant. However a high operation temperature or a stator winding current impulse may cause magnet flux ripple or demagnetization which has direct impact on machines performance. To estimate the magnitude of rotor flux in this paper Kalman filter is used which chooses stator currents and PM flux as state variables. The estimation method can track the distribution of PM flux correctly and is robust to motor parameters uncertainty. The flux linkage harmonics can be derived from the back EMFs by means of FFT analysis. This method can be used to analyse the magnet flux ripple and demagnetization in PMSM. The simulation and experimental results show the effectiveness of the proposed rotor flux estimation method.