Contactless charging and communication for electric vehicles

Charging batteries in electric vehicles needs to cover several aspects including electrical safety, the weight of an onboard charger, different types of chargers needed by different types of batteries, low line disturbance with high efficiency, and the influence of the charging process on the lifetime of the battery. Another important problem is the communication between the vehicle and the outside world during the charging process. This article describes a system combining energy transfer and signal transmission in one unit, which is able to solve all of the above-mentioned problems. Minimal power electronic components are installed in the vehicle. The system uses contactless energy transmission employing an inductive high-frequency coupler. The charging process is monitored and controlled by an onboard charge meter, which can communicate with the converter outside the vehicle via the signal transmission included in the inductive coupler. A laboratory setup able to transfer up to 5 kW was built to demonstrate the performance of the system. The efficiency of the overall system, including all filters, converters, and rectifiers, is at a power level of 5 kW better than 92%. The used gelled lead acid battery, 35 Ah and 288 V, was made from 24 battery modules