Simplified Piecewise Model of Line-Start Permanent Magnet Linear Synchronous Motors

This article investigates the longitudinal end effect of the line-start permanent magnet linear synchronous motor (line-start PMLSM), where conductive ladder rungs embedded into the mover enhances line-start capability but induces the longitudinal end effect due to the eddy current. The longitudinal end effect is first analyzed by virtue of analytical solutions of the electromagnetic field. Then, the coefficient of longitudinal end effect is presented in a piecewise format for convenient application. An algorithm is proposed based on the simplified piecewise theory to evaluate transient responses of the line-start PMLSM. To validate the feasibility of the proposed simplified piecewise theory, cases of the line-start PMLSM are investigated, with which a prototype is manufactured and the theoretical method is proven effective and accurate by experiments. Feasible principles involving the transient characteristics are also investigated via the design cases and experiments. The major contribution of this research is a feasible and convenient method to analyze the transient responses during the line-start process.