Time-based Reliability Analysis of Electrolytic Capacitors for Automotive Applications Using Multi-Domain Simulation

Electromobility expands the range of tasks for electrical auxiliary units in electric vehicles, such as cooling the vehicle battery during the charging process. This doubles the lifetime requirement of the electric refrigerant compressor, which largely depend on the built-in aluminium electrolytic capacitors (AEC). This compressor converts the DC voltage of the high-voltage battery to drive an electric motor with a three-phase AC current. To determine the reliability of the AEC, a multi-domain simulation is presented in this paper, which estimates the aging of the DC-Link capacitors over the entire lifetime of the vehicle. By varying the simulation parameters, conclusions can be drawn about the respective effect of the various physical domains on the service life of the capacitors. The thermal connection of the components plays a major role here.