Wireless Power Consortium Adds Resonant Extension to Qi Charging Spec

The industry’s three wireless charging consortiums -- the standards of which are marketed as Qi, PMA (Power Matters Alliance) and Rezence -- have a significant amount of overlap among member companies, but the wireless charging technologies aren’t interoperable, Perzow said. “They don’t communicate with each other, they don’t work with each other,” and “the details make it impossible for them to be interoperable,” he said.

IHS Technology analyst Ryan Sanderson predicted that over the next few months, companies that have been using magnetic resonance technology “will be trying to use it in a different approach to existing solutions” that use inductive charging where charging elements need to be aligned. He predicted a divide in use cases between the different inductive and resonance-based wireless charging rather than a “one-size-fits-all” solution. He said inductive wireless charging, where charging coils have to couple, will continue to be useful in vehicles, for example, where keeping a smartphone in a stable position is important for safety. “In those instances, it makes sense to use a tightly coupled solution anyway,” he said.

Furniture embedded with wireless charging requires a resonance-based offering where charging coils don’t need to be coupled, Sanderson said. “We're going to begin to see use cases where it might make sense to use one technology over another.” But consumers who want to charge a phone at a Starbucks using a resonance-enabled charging surface and then power up in a car with an inductive Qi charger would have “a problem,” he said. “There isn’t currently an interoperable solution, or the industry isn’t working in an interoperable way."

The situation could be easing, Sanderson said, with the recent announcement that General Motors plans to support Powermat (PMA) and other wireless charging standards in its 2015 vehicles, which would eliminate the need for consumers to choose a standard based on a vehicle’s charging technology. “We're beginning to see solutions that are bridging that gap and offering multi-support,” Sanderson said. “Hopefully it will prompt others to look at similar solutions either on the transmitter side, or it could also prompt building … multi-mode receivers so they can work on different transmitters as well.”

IHS forecasts that 50 million wireless charging-enabled mobile phones will ship this year and that adoption of in-cabin wireless power transmitters supporting multiple standards will pick up next year. Adoption is predicted to accelerate further as the infrastructure supporting multiple standards expands, Sanderson said.

The Alliance for Wireless Power (A4WP) said last week that its Rezence Baseline System Specification Version 1.2 was available to the public. Perzow conceded this week that the announcement from Wireless Power Consortium, along with the impending arrival of Rezence wireless charging products on the market, was part of the reason for the timing of the announcement about the integration of resonance charging into the Qi specification. Philips, LG and others showed interoperability and “mature levels of design at our last members meeting,” said Perzow. Resonance-based Qi products will be out before year end, likely before the spec is released, he predicted.

Instead of promoting wireless charging as a feature by itself, Perzow presented it as an enabler that allows consumers to use their smartphones to full potential. ChargeSpot and Devant Technologies are two companies that offer embedded wireless charging, he said.