FEM calculation of rotor losses in a medium speed direct torque controlled PM synchronous motor at different load conditions

Summary form only given. In direct torque control (DTC), the switching frequency of the converter is not constant but it varies according to optimal switching condition. For example, when driving a permanent magnet synchronous motor at no load operation, the bandwidth of the switching frequency can be several kHz which cause high distortion of stator currents and, therefore, increase in rotor losses. In this work rotor losses of a medium speed permanent magnet synchronous motor driven by a direct torque controlled electrical drive were calculated using 2D time-stepping finite element method coupled with the motion equation. Circuit equations were used in the model in order to take the effects of the distorted phase currents into account. Calculations were performed at different load conditions.