Three-phase current reconstruction applying constant power voltage injection method using three shunt resistors

This paper presents a novel three-phase current reconstruction method for the AC motor drive system based on three shunt resistors. A voltage injection algorithm is adopted to expand the measurable regions for maintaining the motor output power constant. The immeasurable regions are defined by the sample conditions and divided into three sessions by the different voltage injection strategy, which aims at keeping the motor output power constant and satisfying the measurable conditions. In contrast with the traditional current reconstruction method of the drive system with three shunt resistors, the proposed voltage injection method can reduce the fluctuation of the motor torque and benefit the control performance of the drive system. The proposed strategy is realized by a fixed-point DSP and the experiment results are given for the performance verification.