Thrust ripple analysis for improved modular tubular permanent magnet synchronous linear motor

Various technologies have ever been developed to minimize the detent force of linear motors. Although the traditional modular structure can effectively reduce the detent force, the width of the flux barrier and the number of units severely limit its application. To solve these, this paper proposes a new modular type of tubular permanent magnet synchronous linear motor (TPMSLM), which consists of two identical unit motors. For simplification, a subdomain analytical method of the unit motor is firstly established, and its accuracy is verified by a comparison with that of the finite element method. Using the two approaches, the important parameters of the motor are analyzed. A modified two-unit modular TPMSLM is also proposed through the star vectograms of the electromotive force, which achieves thrust performance similar to the traditional three-unit modular TPMSLM with a smaller axial size. Moreover, to make full use of the volume of the flux barrier, end teeth are added at both ends of the unit motors. The simulation results indicate that a reasonable end tooth structure can not only reduce the magnetic leakage phenomenon of the end but also effectively improve the thrust of the motor.