High Power Capacitive Power Transfer for Electric Vehicle Charing Applications

Abstract

Capacitive power transfer (CPT) technology is an effective way to charge electric vehicles. Compared to the conventional inductive power transfer (IPT), a CPT system has three advantages: it does not generate eddy-current loss; it can reduce the system weight and cost; it has better misalignment performance. However, the coupling capacitance in a CPT system is usually in the pF range, which limits the CPT system power and efficiency.

Through overcoming the limitation of this extremely small capacitance, this dissertation has achieved three breakthroughs in CPT technology: the system power is increased from several tens of Watts to several kilo Watts; the transfer distance is increased from 1 mm to hundreds of mm; the transfer efficiency is increased from about 30% to over 90%.

First, a double-sided LCLC compensation circuit has been proposed to realize high-power and long-distance capacitive power transfer. Second, it has also been combined with the IPT technology, using magnetic and electric fields to transfer power simultaneously. Third, the proposed CPT technology has also been applied in dynamic charging, where the vehicle can be charged in moving status. Fourth, the safety issues in a CPT system has been studied, showing that this technology is safe for general public.