Winding factor calculation for analysis of back EMF waveform in air-core permanent magnet linear synchronous motors

This study presents an analytical method for winding factor calculation and back electromotive force (EMF) prediction in air-core permanent magnet linear synchronous motors. In the proposed method, the voltage on each coil of a phase winding is calculated by adding the voltage induced in individual conductors considering a phase shift proportional to the conductor diameter. The proposed method can be used to find back EMF waveform of air-core linear motors with any winding configuration in terms of dimensional specifications of magnet track and winding assembly. Once the back EMF equation is obtained, it can be used to predict the thrust of the motor. The results of the proposed analytical model are compared with finite element analysis results for three different motors to verify the validity of the proposed modelling method. In order to investigate the effect of simplifying assumptions in model derivation, experimental back EMF result on a three-phase eight-pole motor is presented and compared with the proposed analytical model.