A high power factor converter topology for switched reluctance motor drives

A new converter topology is proposed for driving a switched reluctance motor with unipolar currents. It consists of a front-end single-ended primary inductance converter (SEPIC) and a switch in series with each motor phase. All the switches are ground-referenced, which simplifies their gate drives. The available input voltage can be boosted for better current regulation, which is an advantage for low voltage applications. The converter can be controlled to operate at a high power factor with an AC supply. For low power applications, the converter is designed to operate in the discontinuous conduction mode. In this operation mode, it approximates a voltage follower and the line current follows the line voltage waveform to a certain extent. The improved power factor is achieved without the use of any voltage or current sensors. For higher power levels, multiplier control is used with operation in the continuous conduction mode. The simplicity and reduced parts count of the proposed topology make it an attractive low-cost choice for many variable speed drive applications.