January 20, 2016

Developing wireless power charging technology for a "Smart, Happy, and Resilient Society"

Wireless power charger for electric wheel chairs

(January 20, 2016)  In a joint research project, Kyoto University's Center for Innovation (COI), Panasonic Corporation, and Mitsubishi Heavy Industries, Ltd (MHI) have successfully developed a battery-less sensor and wireless power charger for electric wheel chairs.


Wireless power charging technology enables power transmission between distant places via electromagnetic field or electromagnetic waves, thus giving rise to electric devices that require no batteries. This has been hailed as "a game-changing technology" or "a technology that will cause a paradigm shift", and has recently drawn a great deal of attention from the academic and industrial societies worldwide. Kyoto University's researchers have long been engaged in research on wireless power charging technology that utilize microwave power transmission. In an experiment that was publicly released in July 2015, Professor Shinohara and his team used a drone to demonstrate wireless power transmission and sensor technologies.

Battery-less sensor

Research Method and Achievements

A wide variety of research on wireless power charging technologies is currently being conducted, and their standardization and industrial application have increasingly been undertaken in Japan and the world. Most of these research and development activities, however, focus on technologies using the magnetic field, which only allows for wireless power transmission between two points which are practically adjacent to each other. On the other hand, in the current study, the team used microwaves and succeeded in driving a device charged several meters away from the power source. With this technology it's necessary to reduce interference, as the type of microwave used in this technology is also used in mobile phones and other common devices. High efficiency is also required for transmitting energy via radio wave. In this project, Kyoto University and two corporations have jointly developed a battery-less sensor for medical use and a wireless power charger for electric wheel chairs. Panasonic has been working on the battery-less sensor specifically for clinical use, and also developed a new, high-efficient power reception antenna and beam technology for interference reduction. Reducing interference and securing safety are crucial as the wireless power charging system for wheel chairs require a much larger amount of power transmission than a sensor driving system. Using a beam control system that minimizes emission, MHI developed a safe and low-interference system and a microwave oscillator with lower interference.

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