A line start permanent magnet synchronous motor (LSPMSM) supplied with distorted voltage is analysed. The study is based on the field–circuit model. The algorithm for solving the equations of the model is discussed. In the analysis of the selected states of the motor the non–linearity of the magnetic circuit and skewed slots of the rotor are taken into consideration. In order to verify the developed algorithm and software, among others the startup process of the motor has been examined. The electromagnetic torque and phase currents are calculated. The results of computations have been compared to the results obtained using the commercial FEM package Comsol Multiphisics. Selected results of simulation tests are shown.