A novel position sensorless control of flux-switching permanent magnet linear machine for electromagnetic launch

A hybrid observer was proposed for position sensorless vector controlled linear flux-switching permanent magnet motor((LFSPM) of electromagnetic catapult. The observer combined back-EMF with high frequency voltage signal injection to achieve wide speed range operation, while switching process between two control methods is proposed by using smooth function. In order to resolve starting problem of LFSPM, a new initial position estimation was proposed. High frequency voltage signal was injected to obtain the first estimated value of position, and the N/S polarity determination, based on the non-linear magnetizing characteristics of stator core, was suggested as well. All results of s experiment demonstrate the accuracy and effectiveness of the proposed approach, this method is well suitable for the application of electromagnetic launch.