Abstract:Aiming at the cordless direct drive operation of linear motor vertical lifting system (LMVHS), there is an urgent need for a new type of linear motor with high fault tolerance and high thrust density, a five-phase U-shaped permanent magnet salient pole linear motor (FU-PMSPLM) is proposed. The primary set five-phase winding to improve the fault-tolerant performance, and the secondary permanent magnets (PMs) with U-shaped structure can make full use of the PMs. Firstly, from the perspective of reducing magnetic flux leakage, the evolution mechanism of U-shaped magnetic pole structure is analyzed, and the main structural parameters of the motor are given. Secondly, the finite element method (FEM) is used to compare and analyze the electromagnetic characteristics of the U-shaped and Halbach structure of the motor secondary permanent magnet. Based on the principle of constant magnetomotive force, by taking the phase A fault as an example, the fault tolerance performance of the three-phase U-shaped permanent magnet salient pole linear motor (TU-PMSPLM). Finally, the experimental prototype is made and the experimental verification is carried out, the experimental results are basically consistent with the simulation results, which verifies the rationality and feasibility of the proposed motor. The results show that when the amount of permanent magnet is equal, the U-shaped structure of the secondary permanent magnet is compared with the Halbach structure, the amplitude of the air gap flux density increases by 13. 89%, the average thrust increases by 7. 54% and the thrust fluctuation decreases by 25. 07%. FU-PMSPLM has better phase-deficient operation ability than TU-PMSPLM.