Researchers have designed and demonstrated a high-efficiency bidirectional wireless power transfer system for multiple electric vehicles, aiming to support power flow both from the grid to vehicle batteries and from batteries back to the grid. The system is designed to improve interoperability across different vehicle-side assemblies while maintaining high efficiency under a wide range of operating conditions.
The rapid growth of electric vehicle ownership is changing how power systems and transportation systems interact. As vehicle-to-grid, or V2G, technologies develop, electric vehicles are increasingly being viewed not only as transportation tools, but also as distributed energy resources. For this vision to work in practice, vehicles need charging and discharging interfaces that are convenient, safe, flexible, and compatible with different power levels and vehicle configurations.
Wireless power transfer, or WPT, is a promising solution because it can reduce the need for manual cable connection while supporting energy transfer between vehicles and the grid. However, bidirectional wireless charging brings technical challenges. A practical system must handle wide voltage output adaptation, multi-power-level compatibility, efficient operation over broad power ranges, and reliable power flow control in both directions.
The new study addresses these challenges by presenting a bidirectional WPT system with a modular and interoperable design. According to the article, the front-end converter uses a power module that combines a three-phase fully controlled rectifier with a cascaded buck converter. This arrangement provides a wide DC voltage range, helping the grid-side equipment adapt to different vehicle-side requirements.
A key feature of the system is modular activation technology. This allows the grid interface to operate efficiently under varying power demands, rather than forcing all modules to operate in the same way regardless of load. In practical terms, modular activation can help maintain efficiency when the system is serving vehicles with different charging or discharging power levels.
For the bidirectional inductive power transfer link, the researchers propose an integrated scheme for the resonant networks in the ground assembly with cross-frequency compatibility. This matters because interoperability depends not only on power electronics, but also on how the ground-side and vehicle-side magnetic and resonant components work together. The article reports that the performance of the resonant-network scheme was validated through calculations and simulations.
The study also implements a bidirectional power flow control strategy, using voltage regulation and operation mode switching as the main control method. Such control is essential for V2G applications because the system must switch reliably between grid-to-battery and battery-to-grid operation. A charging interface that works efficiently in only one direction would have limited value for future grid-interactive electric vehicle systems.
Experimental results reported in the paper demonstrate interoperability between the same grid-side equipment and different vehicle-side equipment rated at 6, 11, and 30 kW. Under specified aligned-position operating conditions, the system achieved grid-to-battery efficiency ranging from 91.7% to 94.3%, and battery-to-grid efficiency ranging from 89.5% to 93.5%. These results suggest that the proposed system can support multiple power levels while maintaining high efficiency in both energy-flow directions.
Further validation will still be needed across broader alignment conditions, vehicle platforms, grid scenarios, and long-term operating environments. Even so, the study offers a strong indication that interoperable bidirectional wireless power transfer can be engineered for multiple EV power levels. As electric vehicles become more connected to power grids, high-efficiency wireless interfaces could help make charging more convenient while enabling future V2G energy services.
Reference
Author:
Baokun Zhang a , Junjun Deng a , Mengchen Duan a , Chang Li a , Yi Zheng a , Shuo Wang a , David Dorrell b
Title of original paper:
Design and implementation of interoperable high-efficiency bidirectional wireless power transfer systems for multiple vehicles
Article link:
https://www.sciencedirect.com/science/article/pii/S277315372500057X
Journal:
Green Energy and Intelligent Transportation
DOI:
10.1016/j.geits.2025.100307
Affiliations:
a National Engineering Research Center of Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China
b Department of Mechanical and Material Engineering, University of Turku, Turku 20014, Finland
Green Energy and Intelligent Transportation
Experimental study
Not applicable
Design and implementation of interoperable high-efficiency bidirectional wireless power transfer systems for multiple vehicles
2-Jan-2026