Abstract: In order to improve the position sensorless control performance of permanent magnet synchronous

linear motor（PMSLM），a position sensorless control method based on disturbance compensated flux observer

（DCFO）was studied. This method treats the notch filter as a disturbance observer and combines it with a feedback

controller，making it easy to calculate and implement. The parameter debugging in the observer is not complicated，which has a good suppression effect on DC bias and harmonic disturbance，equivalent to overcoming the main limitations of conventional flux observer. In addition，the observer studied will not introduce errors in the amplitude and phase of the magnetic flux. A phase-locked loop was used to estimate the position and speed，further improving the observation accuracy of the observer. The experiment proves that the disturbance compensated flux observer can effectively reduce the estimation error of the mover flux during the operation of the linear motor，thereby improve the estimation accuracy of the mover position and speed.

      Key words: permanent magnet synchronous linear motor（PMSLM）；sensorless control；flux observer；phaselocked loop