Dynamic Strategy for Efficiency Estimation in a CCM-Operated Front-End PFC Converter for Electric Vehicle Onboard Charger

This paper presents a method for efficiency estimation of boost-derived continuous conduction mode power factor correction (CCM-PFC) converters for electric vehicle (EV) onboard chargers. The proposed methodology incorporates converter nonidealities, especially caused by magnetic components. The value of magnetizing inductance in an inductor or transformer core does not remain constant over variable current levels, which causes nonuniform power losses at different current levels. The method proposed in this paper considers a time-variant inductance over various current levels and accordingly establishes a dynamic model of loss estimation. As a proof-of-concept verification, the approach is applied to three different PFC topologies for EV applications and the estimated conversion efficiencies exhibit good agreement with experimentally obtained efficiency values over a wide range of load power from 400 W to 4.6 kW. The deviation of the efficiency predicted from the experimental data is considerably lower in comparison with the existing estimation methods with fixed inductance assumption.