Non-Invasive Supply Voltage Unbalance Detection and Monitoring in AC/DC/AC Converters Using DC-Link Current Analysis

This paper presents a single-sensor solution for the detection and monitoring of power supply voltage unbalances in AC/DC/AC converters. By analyzing the DC-link input current, it is demonstrated that characteristic current pulse deformations directly indicate the presence and severity of grid voltage imbalances. Based on these pulse profile variations, a novel diagnostic metric termed the Current Ripple Voltage Unbalance Factor (CRVUF) is derived. The proposed methodology was comprehensively evaluated and validated through both simulation studies and experimental testing. The presented approach offers a computationally efficient, non-invasive alternative to conventional monitoring systems, effectively reducing the number of required voltage sensors from three to a single current sensor.