For the permanent magnet linear synchronous motors (PMLSM) with high-speed and large-thrust under the periodic transient conditions, the corresponding length and cost requirements are large. This paper designs a toroidal long primary PMLSM. In order to analyze the characteristics of the motor, the expressions of the electromagnetic force and the air-gap magnetic flux density are derived, then the finite element comparison analysis is performed for the linear structure and the toroidal structure

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... of the PMLSM. The results indicate that the space occupied by the toroidal structure is reduced greatly under the same performance index, the required power level has obvious advantages, and the acceleration and braking time are not limited by the stroke. The structure of toroidal PMLSM is further optimized so as to suppress the thrust fluctuation, the comparison of air-gap flux density and electromagnetic force finite element simulation results verifies the validity of the structural optimization. INDEX TERMS TPMLSM, electromagnetic design, electromagnetic thrust, thrust ripple, structure optimization.