Detection of Voltage Asymmetry Based on DC Link Ripple and Analysis of Its Impact on Diagnostic Processes in Complex Electric Drives

Abstract Voltage imbalance can adversely impact electric motors and other equipment interfaced with a three-phase grid. This phenomenon is prevalent in both industrial power systems and various hybrid vehicle architectures. Faults within the voltage generation system may lead to distortions in the direct current link (DC-link) voltage, thereby compromising the efficacy of fault detection and compensation algorithms in electric drives. Consequently, power supply conditions must be accounted for when developing comprehensive diagnostic frameworks for alternating current (AC) machines. As the voltage asymmetry signatures manifest as specific ripples in the DC-link voltage of systems with an uncontrolled rectifier, detection can be achieved using a single sensor instead of the conventional three-sensor approach. This methodology was proposed and validated through both numerical simulations and experimental testing. Furthermore, the study investigated how variations in DC-link capacitance influence the resulting ripple-based asymmetry factor.