A storm is brewing in the world of wireless charging. Over the past few years we have seen a number of consumer products in the market from Powermat and members of the Wireless Power Consortium (WPC) based on inductive technology, sometimes also referred to as tightly coupled technology. Powermat’s efforts have led to the formation of another consortium called Power Matters Alliance (PMA) ostensibly to compete with the large, well organized and well-funded WPC. Although the nod goes to the WPC for the sheer number heavy weight companies supporting the specification, including MediaTek, Nokia, Samsung, LG, Verizon, Philips, and NTTDocomo, the PMA has also lined up some heavy hitting supporters including MediaTek, AT&T, Google, Proctor & Gamble, TI, NXP and Starbucks, with many more joining recently. The PMA specification offers some interesting capabilities around networking that can support active monitoring and metering of power to each device. This feature is attractive to potential providers of charging services, like Starbucks. The PMA, with MediaTek’s support, is also aggressively pursuing an integrated dual mode approach to wireless charging, bringing the resonance and inductive technologies under one unified and interoperable specification.
While industry pundits debate which of the inductive specifications will win the market acceptance battle, other companies and groups, like MediaTek, A4WP, and PowerbyProxi, are talking about a newer technology commonly referred to as resonance but more accurately described as highly resonant loosely coupled technology. The providers of resonant solutions have yet to release a product, but are showing compelling demonstrations at tradeshows and online.
But before we compare and contrast the inductive and resonant technologies, we should first answer the simple question of why wireless charging makes sense at all. Compared to wired charging, all 3 wireless charging technologies have lower efficiency, higher cost, and may not be able to charge at the same rates of power. So there needs to be a compelling reason to want wireless power beyond just the “wow” factor.