Researchers in Kettering University’s Advanced Power Electronics Lab (APEL) are working with HELLA on a more efficient Level-2 EV charger. Presently, level-2 EV chargers on the market have a three-stage design—converting AC grid voltage to 400 VDC; inverting this DC to high frequency AC to feed the transformer; and then rectifying AC to DC again to charge the battery.
Assuming that each stage of that process leads to about a 2% loss of overall power, the overall wall-to-battery efficiency is 94%.
A research team led by Dr. Kevin Bai, associate professor of Electrical Engineering at Kettering University, is working with HELLA to develop a next-generation charger that has a 2-stage design rather than 3-stage design, which would offer 97% efficiency, an improvement of 3%.
By using the novel gallium-nitride devices, the charger switching frequency is also significantly higher, nearly double of the present charger. The design will make the charger ultra compact and light, which eventually will be a game changer for the EV charging industry.—Kevin Bai
The research team includes Bai, a research graduate and a research engineer working on the system design and test. A prototype of the charger is expected to be finished by October and several patents have already been applied for related to this project.
Bai and researchers in his lab have worked with numerous industry partners to develop charging technology, including development of a 24-kilowatt charger for Turkish automaker Derindere Motorlu Araclar (DMA) and development of a 10-kilowatt charger for Magna E-car.