Research of harmonic spectrum of currents in traction drive with PMSM

The paper deals with the significant results of the experimental research of the harmonic spectrum of currents and induced voltages at traction drive with permanent magnet synchronous motors (PMSM). The experiments were done in a special workplace with a real traction drive for wheel vehicles. The harmonic spectrums of currents were analyzed by a specialized device on the basis of a central measuring station. The knowledge of marked subharmonic components of stator winding currents is the most significant finding of these experiments. The frequencies of these components are given by multiples of frequency of mechanical speeds. The subharmonic components also pass to the dc current at an input site of the traction inverter. This fact is particularly important from the viewpoint of legislative requirements to electromagnetic compatibility (EMC) of drive with railway interlocking devices.