The University of Tokyo, in collaboration with Denso, Bridgestone, NSK (NSK), and Rohm, has developed a system that can wirelessly power the tires of a moving vehicle from the road. By devising the arrangement of the coils built into the tire, the efficiency of power transmission was improved, making it possible to transmit a larger amount of power than before. If wireless power can be supplied to electric vehicles (EVs) while they are running, the cruising range can be extended and the capacity of the on-board battery can be reduced.
Since the road-to-tire wireless power supply system uses a magnetic field to transmit power, it is important to shorten the gap between the power transmission coil on the road side and the power reception coil attached to the hub of the wheel. In this system, the distance between the coils can be shortened by incorporating relay coils in the tires and wheels.
Power is supplied to the relay coils in the tires and wheels, and the power is transmitted from the relay coils to the power receiving coils without contact. A wire is connected between the two relay coils, so power can be sent even with a metal wheel. The receiving coil and the battery on the vehicle side are also connected by wire.
This system was developed based on the third-generation In-Wheel Motor (IWM), which was announced in 2019 by the University of Tokyo and four other companies, and which can be powered wirelessly from the road while driving. This is an initiative in the “Social Collaboration Course” established in 2020 by the University of Tokyo and four companies. The course plans to focus on research on EV drive systems in the future.