Coupling is a term widely used in discussing wireless power systems – it refers to a coupling coefficient ‘k’ which defines how well a transmitter and receiver are magnetically “linked” as a percentage. Generally something like transformers have extremely high coupling coefficients approaching 100%.
Technically, tightly coupled systems are interpreted as having high or transformer like coupling coefficients while loose coupling is interpreted as systems with low coupling coefficients. There is some debate around the cut-off for high and low – 50% is one proposed transition point.
From a usability perspective I would define tightly coupled as a system which requires some form of mechanical alignment to fix orientation and transmission distance. This can be done via a magnet or a mechanical alignment feature on the transmitter and receiver. A loosely coupled system would allow complete flexibility of orientation / misalignment in a 2D target zone. A 2D target zone would be a planar area such as a matt (i.e. Proxi-2D), which can wirelessly charge devices imbedded with a receiver that is a few cm above it.
Systems like the Proxi-3D which enables receivers to work in a three dimensional target zone with an omni-directional receiver are what a user may call as beyond loosely coupled!
In my opinion the usability definition is more relevant for anyone buying the system as really the technical definition is really just a means to an end – the end being ensuring customers don’t have to carefully align their devices with a wireless charger.
The CEA has formed 2 working groups to drive specifications, with the goal of establishing a large market for Consumer Electronics:
WG4 System Requirements for Highly Resonant Wireless Power Systems
Summary: “WG4 is developing ANSI/CEA-2042.4. This standard will define system requirements for highly resonant wireless power systems. Highly resonant wireless power systems are systems that transfer power wirelessly using magnetic induction, and that require magnetic resonance.” This is also referred to in the industry as loosely coupled.
WG5 System Requirements for Tightly-Coupled Wireless Power Transfer
Summary: “WG5 is developing ANSI/CEA-2042.5. This standard will define system requirements for a tightly coupled wireless power system. A tightly coupled wireless power system is an inductive wireless power transfer system with a strong magnetic linkage between the primary and secondary coil.”
Why would any consumer care for another tightly coupled solution? Isn’t this just another manifestation of the specification released by the Wireless Power Consortium with all its limitations?
I believe WG4 is solving real customer needs to enable practical solutions for Consumer Electronics. Don’t you?
PowerbyProxi is a member of WG4 and one of the main contributors to this specification. We are leveraging our world class team in wireless power and many years of delivering practical solutions that customers want.
Let me now your thoughts.