Off-line Compensation Method for Current Scaling Gains in AC Motor Drive Systems with Three-phase Current Sensors

This paper proposes an off-line compensation method for current scaling gains in AC motor drive systems with three-phase current sensors. Applications such as elevators and hoist cranes generally measure three-phase currents directly using three current sensors in preparation for the fault of a current sensor. This paper analyzes the effect of current scaling gain errors on neutral current which is calculated with measured stator currents. Based on the analysis, a compensation strategy for the current scaling gains is presented. Experiments were carried out and the experimental results demonstrate the validity of the proposed method. The proposed method is applicable in the initial commissioning procedure for both cases that rotor is locked or not.