Improvement of Transmission Efficiency on Inductive Wireless Power Transfer at a Middle Distance

This research focuses on Wireless Power Transfer (WPT) systems, especially the inductive coupling type. The WPT systems applied to the battery charger system of Electric Vehicle (EV) and Plug-in Hybrid Vehicle (PHV) are investigated. In this application, it is necessary to keep the inductive coupling coils at a short distance and set the coils appropriately in order to achieve high transmission efficiency. These conditions are usually too strict for the battery charger to be applied to home appliances because we stop a car in a parking lot roughly. In this paper, the inductive WPT system is applied to the battery charger system for EV and PHV at the parking lot. When the car is stopped inside the parking lot roughly, the efficiency of transmission becomes lower because the distance between the inductive coupling coils becomes longer. We propose two methods for improving the transmission efficiency. We verify our proposal by the simulation and experiment.