Why Magnetic Resonance
There are 3 key capabilities of resonant wireless power that uniquely deliver compelling user experiences.
The first is Spatial Freedom. Your electric toothbrush uses Magnetic Induction (MI), similar to the technology of a transformer. With induction, two matching coils must be precisely oriented to each other and be effectively touching for power to transfer. This is why your electric toothbrush must be precisely placed on a stand. With Magnetic Resonance (MR), you have the flexibility to “drop-and go” charging that is central to a positive user experience.
The second is transmitting power through materials. MR can move power over a distance, but that can also be through wood, stone, glass, concrete, asphalt and the like. The PTU charger can be mounted under a desk, or embedded in the dry wall.
The third is charging multiple devices. With resonance, from one PTU power source, you can charge multiple devices at the same time. Each device, as it arrives at the source, can efficiently draw the power it needs. In our connected lives with multiple battery-powered devices, having a common charging source that can feed all our devices is again central to a positive user experience.
(excerpt courtesy of Witricity Corp. minor modifications by JJPlus)
From the view of JJPlus, MR is fundamentally a more feasible wireless power transfer technology over MI for the infrastructure’s deployment towards a truly widespread installed bases of public charging hotspots due to the following 2 major reasons:
– for restaurants and meeting rooms etc. business owners hate the idea of drilling holes to their expensive table or desk in order to have an MI transmitter installed while exposing its charging surface. Without drilling, an MI transmitter is placed on the table without being able to hide its power cord. MR transmitters, on the other hand, can be mounted under the table and the result is easy installation and simply elegant.
– An MR transmitter allows spatial freedom within its effective charging area for “drop-and-go” charging on the table while MI offers only a precise spot. When a multiple-device-charging-capable MR transmitter is used, a common area is provided for multiple devices to charge simultaneously. Conversely, MI can support only one-to-one charging. This means multiple transmitters have to be installed on the table and therefore multiple holes drilling is involved which results in extremely expensive labor cost. And once the holes are drilled, there is no turning back!
Many phones are embedded with MI receivers, so what can MR transmitters do?
The recent article (here) about Powermat’s release of their Charging Spot 4.0 to add the support of Inductive Qi standard (MI based) on top of their existing support of Airfuel Inductive standard (still MI based) is a very straight forward move in response to Apple’s announcement of Inductive Qi support. Is this move the holy grail to solve the current world’s real problem? Not quite. Given the fact that Resonant Qi is still fighting the laws of physics to maintain backward compatibility, until it’s done, the real world still need a solution NOW that works for all kinds of user situations. JJPlus agrees with Powermat’s move to support both wireless power standards’ MI based devices, however, we believe that by maintaining the advantages of AirFuel Resonant (MR based) while adding an extension to support Inductive Qi is a better approach.
A hybrid wireless charging system
The objective of our hybrid wireless charging system is to meet the following 6 criteria:
1. Full spatial freedom
2. Under table transmitter installation/no drilling
3. Resonant power through thick surfaces of different types
4. Multiple devices charging, one single transmitter
5. Full compatibility with both Inductive Qi and Airfuel Resonant
6. Legacy support to still billions of phones requiring wired charging
To meet the above-mentioned criteria, we start off with the abundant power of WCTC301 wireless power transmitter charging base with the capability to 1. provide 16W of resonant power through a distance of 46mm, enough to charge up to 3 phones (5W each) simultaneously and 2. under table installation to power through a typical thick table. Second, we designed a ‘Power bridge’ WCRB401 which is a Qi compliant transmitter stand (for charging a Qi compliant phone) that receives the resonant power, at the base of the stand, from WCTC301. When this Power Bridge is placed within WCTC301’s effective charging area, full spatial freedom is supported and the user can still operate the phone while charging in the upright position. For legacy support, we offer an optional 3-in-one cable with selectable Lightning, Micro-USB & Type C connector on one end, and the other end connects to the power bridge. With this hybrid wireless charging system, all of the 6 criteria are met – No compromises on delivering compelling user experiences. No compromises on full compatibility and No compromises on supporting legacy devices!
(note: for infrastructure deployment, WCTC301 is equipped with WiFi connectivity and the API necessary for the remote management of your wireless power network)
Table of Comparison
Typical Qi Powermat Charge Spot 4.0 JJPlus WCTC301 Hybrid
Spatial Freedom NO NO YES
Powers Through Surface NO, typical 5mm power delivery distance YES, up to 40mm power delivery distance YES, up to 50mm power delivery distance
Maximum Transmitter Power 5W (Typical) 15W (as of today) 16W (as of today)
Under Table Installation (a.k.a. No Drilling) NO YES YES
Multiple Devices Charging NO NO YES
Dual Wireless Power Standard Suppot NO (Qi only) YES (Qi and Airfuel Inductive) YES (Qi and Airfuel Resonant)
Legacy Support for Wired Charging NO NO YES
Wireless Power Network Remote Management NO YES YES
Examples of jjPlus’ public wireless charging hotspots
jjPlus wireless charging systems have been installed in public places such as coffee shops, convenience stores, bars, fitness centers and so on. For example, FamilyMart, one of the largest convenience store chains in Asia, has jjPlus’ systems installed in its 1,000+ stores in China’s Hangzhou and Chengdu cities. Each store can provide, typically, 8 simultaneous wireless charging sessions via WCRB401 or WCRDG04 from the transmitter choice of either WCTC301 or WCTC202.