A New Phase Current Reconstruction Scheme for Four-Phase SRM Drives Using Improved Converter Topology Without Voltage Penalty

Accurate current detection is of crucial importance for the operation and fault diagnosis of motor drives. In this paper, a new phase current reconstruction scheme is proposed for four-phase switched reluctance motors (SRMs) by using one dc-link current sensor without voltage penalty. First, an improved converter topology is proposed, which has fewer electronic components and a more compact structure compared with the conventional asymmetrical half-bridge converter. Then, an advanced pulse injection technology is developed to obtain the phase currents. By using the proposed approach, the cost and volume of the motor drive are reduced and the reliability of the system is improved. Most importantly, the scheme proposes a promising solution to the voltage penalty problem caused by the other existing strategies, which significantly increases the sampling accuracy without the restriction of the duty cycle of injected pulse. In order to verify the effectiveness of the proposed method, three classical control schemes including angular position control, current chopping control, and voltage pulse-width modulation control are all performed in the closed-loop system. The simulation and experiments based on a 150-W four-phase 8/6 SRM are carried out to validate the feasibility of this proposed scheme.