Abstract: Although apparently simpler, the SRM drives are nowadays more expensive than their conventional AC drive counterparts. This is to a great extent caused by the lack of a standardised power electronic converter for SRM drives, which would be available on the market as a single module. A number of attempts were therefore made in recent times to develop novel power electronic converter structures for SRM drives, based on the utilisation of a three-phase voltage source inverter (VSI), which is readily available as a single module. This paper follows this line of thought and presents a novel power electronic converter topology for SRM drives, which is entirely based on utilisation of standard inverter legs. One of its most important feature is that both magnetising and demagnetising voltage may reach the DC-bus voltage level while being contemporarily applied during the conduction overlap in the SRM adjacent phases. At the same time, the voltage stress across the power switches equals the DC-bus voltage. The topology is functional in all operating regimes of the drive. Principle of operation is explained in detail for a three-phase SRM drive and experimental results, obtained with a 6/4 switched reluctance motor, are included. Four inverter legs are required in this case. Some considerations, justifying the proposed converter topology from the point of view of the cost, are included.
Keywords: Voltage source inverter, semiconductor switch, switched reluctance motor, motor drives.