Power Electronic Converters to Drive Switched Reluctance Machines
This chapter introduces several converter topologies for the SRM drives and then gives comparative evaluation of power converters. The asymmetric bridge converter for a three-phase SRM is the most widely applied converter in SRM drives. It allows independent current control of different phases and, therefore, it maintains good torque control. However, it includes two switches and two diodes per phase, which is costly for low-cost applications. In SRM drives, the phase winding does not conduct during the whole electrical cycle. Therefore, some of the power devices can be shared between different phase windings and the number of the switches can be reduced. As compared to conventional two-level converters, multi-level converters have several advantages, such as lower magnitude of current ripple, lower power losses at high switching frequency, lower common-mode voltage, and lower electromagnetic interference.