Capacitor Condition Monitoring for Modular Multilevel Converter Based on Charging Transient Voltage Analysis

This article proposes a capacitor condition monitoring (CM) method for modular multilevel converter (MMC) in motor drive applications. The proposed method is based on wavelet decomposition of transient voltage signals, which is independent of modulation schemes and control strategies. The equivalent series resistance (ESR) change can be detected with a moderate computation requirement. Both simulation and experimental results have verified the performance of the proposed method.