Cost-optimized switched reluctance motor drive with bipolar currents

Abstract

The manufacturing cost of switched reluctance motors (SRM) are low due to concentrated stator windings and extremely simple and robust rotor construction, having neither permanent magnets nor the rotor windings. Therefore, the SRM drives have been considered as a promising solution for cost-critical applications where the electronic speed control is needed, such as the appliance drives, HVAC blowers and compressors, drives in commercial and residential buildings and similar. One of the reasons that hindered the SRM drives expansion was the lack of standardized power converters produced in volume. Advantageous SRM power converter topologies have been proposed over the years, however, some of them were utilizing a large number of discrete power components, while the others were leading to a poor utilization of the DC-bus voltage. In this article, a novel SRM drive is proposed, entirely based on standard industrial inverter modules, fully utilizing bus voltage. Besides, due to the pulse polarity alteration, the dwell period can be arbitrarily chosen and can freely overlap defluxing interval in the adjacent phase. Therefore, the applicable voltage reaches theoretical maximum for the given bus voltage, extending in such way the torque-speed region up to the motor-related limits. Proposed topology is functional in the four quadrants and in the field weakening as well. This article includes the operation principles of the proposed solution and continues with practical application on a three-phase SRM. Also, design considerations and experimental results are included, as well as the consideration of the drive cost. © Springer-Verlag Berlin Heidelberg 2007.