An Online Proactive Health Monitoring Method for Output Capacitors of Vehicular Auxiliary Converter

The auxiliary converter is the power source of the vehicular electronic system, the failure of which may cause inestimable economic loss. As the most age-affected component in the converter, the online health monitoring for output aluminum electrolytic capacitor (AEC) is of great significance. Throughout the full-life period of AEC, the capacitance (
$C$
) will fall and the equivalent series resistance (ESR) will rise. This article proposes an online proactive health monitoring method for output capacitors of a 1-kW vehicular auxiliary converter. The operating mechanism of the two-level Boost-LLC converter is analyzed and the ESR calculation model is derived in detail. A novel ripple measurement approach and a peak current calculation method are proposed. Both ripple measurement and current approximation are confirmed to be practical and applicable. Finally, the online health monitoring platform is built. The experimental results can show the effectiveness of this method. The monitored ESR can indicate the healthy degree for the output capacitors in the auxiliary converter. The influences of switching frequency and ambient temperature are verified to express the superiority of the online monitoring scheme.