Wi2M: Efficient Multi-Coil Wireless Charging with Smart Dual-Mode Transmitter-Relay Design

• Applicant: Professorin Dr.-Ing. Ghada Bouattour, Ph.D.
• Subject Area: Electrical Energy Systems, Power Management, Power Electronics, Electrical Machines and Drives ; Hardware Systems and Architectures for Information Technology and Artificial Intelligence, Quantum Engineering Systems
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 567823957

Planar multi-coil wireless charging is an advanced power transfer technology that enable efficient energy transfer via electromagnetic induction. This system enhances the charging process by providing a larger and more flexible charging area, allowing for improved alignment tolerance and faster power delivery. By incorporating multiple coils, it supports the simultaneous charging of multiple devices and reduces charging times compared to traditional single-coil systems. This flexibility is achieved using multiple transmitter coils or relay coils (resonator coils), which consist of an inductor coil paired with capacitors. These relay coils help utilize the leakage magnetic field and tune the system to a resonant frequency for efficient energy transfer. Typically, in a planar multi-coil wireless charging system, when a transmitter coil is active, its magnetic field can influence nearby inactive coils, causing leakage that can be compensated for with relay coils. However, such a system does not provide dynamic control of the main transmitter coil and relay coils due to the lack of circuits supporting dual-mode operation at high frequencies. We propose a novel dual-mode transmitter-relay multi-coil system for battery-free devices featuring a high-frequency H-bridge inverter with resonant topology for both transmitter and relay modes, as an approach not previously investigated. While resonance topologies have been studied for transmitter coils, they remain unexplored for relay coils. Our investigations address frequency splitting from coil over-coupling through innovative resonance design and a smart activation strategy based on load impedance and receiver position. This system detects receiver location, activates appropriate sending and relay coils, based on accurate coupling factors models to prevent frequency splitting. This novel charging approach offers significant benefits for consumer electronics, electric vehicles, and other wireless power applications. Despite high demand, effective multi-coil supply systems remain challenging to implement. We will test our approach on a 10-watt battery-free system designed for large-area charging, balancing efficiency, adaptability, and computational requirements. The technology shows promise for diverse applications including industrial tools, sensors, and consumer electronics.

• DFG Programme: Research Grants