EKF-based online angle-error estimation of PMLSM using disturbance observer

Contributing to the control performance and stability of the system greatly, the angle information is important to vector control of the synchronous motor. Angle-error exists and accumulates due to the inaccurate initial phase-angle positioning, the non-ideal installation of the encoder or magnetic poles, encoding signal loss et al., which is particularly prominent in non-rotating permanent magnet synchronous linear motor. In this paper, the equations of the motor system, where the angle-error is treated as an extra state, are deduced utilizing the transformation relationship between the actual coordinate and the measured coordinate. Eventually, the angle-error is estimated by using the extended Kalman filter technology, which is verified by both simulation and experimental results.