Reliability and Condition Monitoring of DC-Link Capacitors in Power Electronic Converters
Neha Singh *
Department of Electronics and Communication Engineering, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand 263145, India.
Deep Sehgal
Semiconductor Laboratory (SCL), Ministry of Electronics and Information Technology (MeitY), Mohali, India.
*Author to whom correspondence should be addressed.
Abstract
Background: DC-link capacitors play a central role in buffering energy, limiting voltage ripple and supporting reliable operation of power electronic converters.
Aim: To organise the reliability and condition-monitoring problem for DC-link capacitors used in power electronic converters.
Study Design: A focused narrative review covering electrolytic, film and ceramic capacitor technologies, ageing mechanisms and online monitoring.
Methodology: Seventeen journal articles were compared according to capacitor technology, converter topology, measured parameter, uncertainty and deployment limits. Targeted searches were updated on 8 August 2026; no new ageing experiments were performed.
Findings: Temperature, ripple current, voltage stress and humidity drive different degradation processes. Capacitance and equivalent series resistance are useful indicators, but either parameter alone can misclassify capacitor health. Online methods based on ripple, transient response or controlled signal injection can reduce maintenance uncertainty when assumptions are stated.
Conclusion: Capacitor health monitoring should be designed with converter control and measurement boundaries in mind. A useful indicator must be observable during normal operation and linked to a defined end-of-life criterion.
Keywords: DC-link capacitors, condition monitoring, reliability, equivalent series resistance, electrolytic capacitors, film capacitors