Automatic Containment of Field Exposure for Roadway Wireless Electric Vehicle Charger

Abstract

Inductive power transfer (IPT) has found application prospect in dynamic wireless electric vehicle (EV) charging as it can avoid the constraints of physical connection. With the commonly-used LCC compensation, the ground-assembled transmitter coil is always excited by a fixed standby current even if there is no receiver coil coverage. As for dynamic wireless power transfer (DWPT) systems, even without EV charging, the underground transmitter coils typically remain activated at full power output to wait for the receivers in most cases, resulting in huge standby current and magnetic exposure safety concerns. In this paper, we proposed a method for automatic containment of field exposure caused by standby current in the transmitter coil of wireless chargers, which applies LCC compensation networks requiring only primary-side control with the elimination of wireless feedback communication and extra detection. The wireless chargers can be automatically deactivated once EVs depart, as well as automatically activated once detecting the presence of EVs. Also, its excellent interoperability for different loads and types of compensation topology has been well analyzed and then verified. Moreover, experiments demonstrate that the magnetic field exposure is merely 11.66% of the ICNIRP 2010 standard exposure limit with proposed modulation, which is suppressed by 94.64% than before.