For wireless power transmission (WPT), the electromagnetic induction method makes use of a physical phenomenon discovered in the upper half of 1800s. As known widely, a current that passes through a coil produces a magnetic field around it. This electromagnetic effect was discovered by Hans Oersted, a Danish physicist in 1820. A non-electrified coil that comes close to the magnetic field has a current induced in it, which may light up a light bulb. This coil-to-coil power transmission was discovered by Michael Faraday, a British physicist in 1831, who called it “electromagnetism.”
Currently, most of the WPT-compatible smartphones and chargers in the market comply with the Qi standard developed by the Wireless Power Consortium (WPC) headquartered in the US. The Qi standard, which has its name from the Chinese “Qigong,” is led by Panasonic Corporation of Japan, Samsung Electronics Co., Ltd. of South Korea, Sony Ericsson Mobile Communications of the United Kingdom, Nokia Corporation of Finland, and Denso Corporation of Japan. The electromagnetic induction WPT standard of WPC, including the “magnetic resonance method,” the “electric wave reception method” and others, has been joined by a number of manufacturers of household appliances and automobiles in many countries. By implementing the Qi standard, any product that bears the Qi mark can be charged wirelessly, regardless of who actually manufactured it.
Technologies that compete against the Qi standard are divided into electric field coupling, magnetic resonance and line/resonator coupling.
(1) Electric field coupling, also termed “electrostatic induction,” is a kind of technology which makes two components (such as capacitors) that have a larger electrostatic capacity to exchange power by close spacing. Murata Manufacturing Co., Ltd., Takenaka Seisakusho Co., Ltd. and other Japanese manufacturers have engaged in developing this method.
(2) Magnetic resonance is to increase the resonance between the supplying and receiving devices in electromagnetic induction.
(3) Line/resonator coupling is to exchange power by using the traveling wave path and resonator in the light communications technology and the high-frequency circuit technology. It is used to supply power to moving receiving devices whenever necessary. The Ryukoku University and other research and development (R&D) groups have engaged in developing this method.
I. Development of WPT-related standards
Currently, increasing competition is witnessed in the area of WPT-related industrial standards. The WPC developed a de facto standard since its establishment in 2008. It formulated a preliminary standard specification (the latest being V1.1) for products with an output power of 5W or less in July 2010. It now engages in developing a charging standard for medium power-consuming devices (less than 120W).
On the other side, Samsung Electronics of South Korea and Qualcomm Inc. of the United States jointly stated on May 7th, 2012 to establish a WPT-related industry group, the Alliance for Wireless Power (A4WP), with members including Samsung Electronics of South Korea, Funai Corporation of Japan, Qualcomm Inc. of the US, Broadcom Corporation of the US, SK Telecom Co., Ltd. of South Korea and NXP Semiconductors Netherlands B.V. of the Netherlands, etc. The total 35 member companies, however, are far fewer than the 137 members of the WPC. The A4WP promotes WPT technologies that provide a higher level of positioning freedom between the power supplier and the power receiver, supply power to automobiles and desktop products, and supply power to more than one product at a time. The related standard is based on magnetic resonance WPT technologies and its first version has been published internally in October 2012. It is noteworthy, however, that Samsung Electronics of South Korea, as a formal member of the WPC, worked with Qualcomm Inc. of the US to establish the A4WP. Why it has acted in this way is worth our consideration. As far as this author can see, this parallel strategy reflects that the company wants to remain aware of how the development of the WPC is proceeding while simultaneously developing its leadership in the WPT arena.
Moreover, Funai Corporation of Japan, Haier Group of China, BURY Technologies GmbH & Co. KG of Germany, Elec & Eltek International Co. Ltd. of Singapore, Ever Win International Corporation, IDT Corporation, NXP Semiconductors Netherlands B.V., Peiker Acustic GmbH & Co. KG of Germany, Renesas Electronics Corporation, Tennrich International Corporation, Texas Instruments Inc. of the US, Triune Systems, Wurth GmbH and Underwriters Laboratories, a total of 15 companies, are members of the both alliances.
Qualcomm Inc. plans to use and promote the magnetic resonance “Wi Power” to compete against the Qi standard. “The Wi Power is technically more advantageous in which the supplier device and the receiver device can be even farther away from each other.”
Moreover, though as a member of the WPC, Samsung Electronics has engaged in developing its own technologies, such as the magnetic resonance WPT technology equipped in the charger dock for 3D goggles launched in January 2011. As early as in October 2011, it indicated, “The magnetic resonance method allows for a higher level of positioning freedom between devices, supplies more than one terminal at a time, and has a wider application scope.”