Efficiency Analysis of Delta Winding Connected BLDC Motor According to Occurrence of Circulating Current

This paper studied the effect of circulating current generated in a surface-mounted synchronous motor (SPMSM) with delta winding on efficiency. In a delta-connected motor, when the 3nth component occurs in the phase basck electromotive force (BEMF), a circulating current that flows only inside the circuit occurs. This current causes additional joule losses and degenerate motor performance. In this paper, the 3nth component of the phase BEMF was reduced by chaging the shape of the permanent magnet of SPMSM, and the performance of the motor was compared. For this purpose, a six step dirve was used, and the loss was separated into copper loss and iron loss according to the torque and speed of the motor. At this time, copper loss was divided into loss due to the fundamental wave and the 3nth component of the phase current. Finally, an efficiency map according to torque and speed was presented, and the diifference in efficiency between the basic and improved models was analyzed. The performace of the prototype was verified by a dynamometer load test.