Bi-directional Wireless Power Transfer for Vehicle-to-Grid : Demonstration and Performance Analysis 2019-01-0870
In an effort to address environmental concerns and enhance energy security, automakers have been developing electrified products such as plug-in hybrid vehicles and battery electric vehicles for the past several years, and they are gaining momentum. Honda strives to electrify two-thirds of global automobile unit sales by 2030. Simultaneously, Renewable sources of energy have been playing an increasing role in the nation’s electricity grid. Due to the intermittent nature of many renewable sources it is difficult to maintain a balance between renewable energy availability and coincident peak demand. One potential solution is to store the “excess” electricity generated by renewable sources, and then feed it back into the grid during the peak demand periods. The growing number of battery electric vehicles in the market offers a possible storage medium as well as the ability to provide energy on demand when coupled with Vehicle-to-Grid (V2G) technology. V2G technology enables two-way power flow between the grid and the high-power, high-capacity propulsion batteries in an electrified vehicle. This technology can therefore contribute to stabilizing the balance between supply and demand on the power grid. Previously the authors performed an architectural design and simulation study to show that V2G functionality can be achieved with a bi-directional wireless charging system. Recently the authors extended this work and developed a prototype to prove the concept and verify the result of the simulations. The goal of this research activity was to adapt an existing uni-directional system design to enable bi-directional wireless power transfer with minimum impact to system cost, while maintaining full compatibility with the requirements of SAE J2954. This paper discusses the performance of the prototype system, including output power and efficiency for power flow in both Grid-to-Vehicle (G2V) and V2G operation. Full power transfer and end-to-end efficiency greater than 93% was achieved in both directions.