Phase Current Reconstruction of Switched Reluctance Motors From DC-Link Current Under Double High-Frequency Pulses Injection

Abstract

Switched reluctance motors (SRMs) have been considered as low-cost machines for electric vehicle (EV) and hybrid EV applications. However, the current sensors used in the system will not only increase the cost and volume but also degrade the running reliability of the motor drives. Conventionally, the current sensors are used in each phase winding individually to obtain these phase currents. To reduce the number of current sensors, a four-phase 8/6-pole SRM is applied to analyze the working states, and a novel phase current reconstruction method from the dc-link current employing double high-frequency pulses injection is then proposed. Two kinds of high-frequency pulses with large duty cycles and phase shift are injected to the down switches in each phase, respectively, when the phase currents are overlapped in the turn-on region, and the dc-link current is decomposed to reconstruct phase currents in both current chopping control system and single pulse control system. The transient performance in a closed-loop system based on the phase current reconstruction scheme is investigated. The proposed method uses only one current sensor in the dc link and requires no additional circuits. The simulation and experimental results are presented to confirm the implementation of the proposed method.