An Improved DC-Link Series IGBT Chopping Strategy for Brushless DC Motor Drive With Small DC-Link Capacitance

This article proposes an improved DC-link series IGBT chopping strategy for the brushless DC motor (BLDCM) drive equipped with a small DC-link capacitor fed by single-phase AC source. In this strategy, different vector sets are established according to the switching state of the DC-link IGBT and the operation mode of BLDCM. By analyzing the effect of each vector on phase current change rate, a vector selection-based current control scheme is presented. In particular, when the rectifier output voltage is less than the average line voltage of BLDCM, the combined action of vectors with only DC-link IGBT chopping is designed, in order to decrease the converter switching times and reduce the DC-link capacitance at the same time. In addition, the constraint of the DC-link capacitor voltage is analyzed to satisfy the reliable regulation of the motor phase currents, and the calculation method of the DC-link capacitance is given furthermore. The proposed strategy can achieve the smooth operation of the motor with small DC-link capacitance. Meanwhile, the total switching times of the converter are reduced, thereby improving the converter efficiency. The contrastive experimental results verify the correctness of the theories and the effectiveness of the proposed strategy.