Hybrid Frequency and Pulse Width Modulations for Minimizing Standby Current in LCC Transmitter

Inductive power transfer has been extensively researched in recent years as it avoids the safety hazards of wire connections, which provides the possibility of dynamic charging for electric vehicles (EVs). The LCC compensation is commonly used in wireless chargers for EVs owing to its ability to generate a constant current in the transmitter coil without control. However, the coils buried underground are still activated to output power waiting for the receivers in most occasions even though there is no EV being charged, which creates a huge standby current and leads to magnetic exposure safety issues in the surroundings. In this paper, we proposed an interoperable method for LCC compensated chargers requiring only primary-side control without the need for wireless communication and extra detection. The chargers can automatically activate wireless charging once detecting the presence of EVs, as well as automatically shut down once EVs depart. Experiments demonstrate that the standby current is reduced by about 90%, and the magnetic exposure is suppressed by 94.64%. The automatic activation and deactivation during dynamic wireless charging are also realized through proposed control method. Moreover, the excellent interoperability for different loads and secondary compensation types has been verified as well.