Performance Optimization of Dynamic Wireless EV Charger Under Varying Driving Conditions Without Resonant Information

Abstract

On-road dynamic charging of electric vehicles by wireless power transfer (WPT) systems has emerged recently as a cost-saving means for modern transportation. Thus, maximizing power transfer efficiency is essential in the system design stage as well as during the operation. In addition, the voltage regulation of EV power bus, supplied by the power transfer system and battery, is needed for a long life of the battery. In this paper, these two requirements are fulfilled under varying EV driving conditions by a single control system applied to a wireless power transfer system. The control system simultaneously tunes the switching frequency of the primary side inverter and the conversion ratio of the secondary side converter to achieve the maximum possible efficiency. In addition, the system adjusts the duty cycle of the primary side inverter to regulate the output voltage. Furthermore, an allowable range for the optimal frequency is determined and imposed to the primary inverter to compensate the power factor reduction according to IEEE std-1547.1. The system needs just one dc/dc converter instead of two as reported in the literature, without any restriction in zero state and start-up conditions. The control system does not need any information of the coupling coefficient and compensating circuit elements. The system is applied to a 710 W experimental wireless power transfer setup. Extensive simulation and experimental results are presented to validate the proposed control system.