Thrust force control of PMLSM based on disturbance observer and thrust force observer
                                                                                 JI Mingli1, QIAN Houliang2
(1.College of Electric Engineering and Automation, Jiangsu Maritime Institute, Nanjing 211170, China;2.Industrial Center, Nanjing Institute of Engineering, Nanjing 211170, China)

Abstract: In order to solve the thrust ripple caused by uncertainties of high precision permanent magnet linear synchronous motor (PMLSM), such as parameter variations, external disturbances, friction forces and endding effects, a method combining disturbance observer (DOB) with thrust force observer (TFOB) was proposed. DOB was used as an inner loop controller to suppress and compensate the influence of uncertainties on the system，and to reduce the influence of measurement noise on the system. At the same time, TFOB was designed as an outer loop controller to solve the problem that DOB cannot suppress the thrust ripple of PMLSM system，and ensure the accuracy of DOB input. The environmental contact model was established to identify the parameters causing thrust ripple offline, thus improving the thrust control bandwidth. The experimental results show that compared with DOB control method, the thrust force control method based on DOB and TFOB achieves better control performance in both smooth operation and sudden disturbance condition.

Key words: permanent magnet linear synchronous motor(PMLSM); thrust ripple; disturbance observer(DOB); thrust force observer(TFOB)