WPT breaks all connections, Part 3

Technology News |
By eeNews Europe

WiPowering the Future

There was another almost concurrent success story based on another ongoing university project. In 2004, a spinoff company called WiPower had emerged from the shadows of University of Florida, where its founder Ryan Tseng had been exploring WPT for some time, reportedly having been thoroughly disgusted carrying bags of wall-warts/adapters all over the world on his many trips. He had dreamed of a charging pad on which he could just throw his mobile phone along with any other rechargeable battery-powered gadgets such as mp3 players, media tablets, PDAs and perhaps even laptops, and have them charged overnight. Over the following three years, his new-born company continued R&D efforts along with the University of Florida.

Note that to dispel the “inherently poor efficiency’ popular myth of MR-based systems, WiPower had declared back in 2009 that its prototype wireless chargers operated at about 60% efficiency, and that it had achieved higher than 75% in testing.

In September 2010, Qualcomm acquired WiPower. The A4WP group was formed in May 2012 by Samsung and Qualcomm, with some help from Powermat (pioneers of PMA surprisingly), SK Telecom, Ever Win Industries, Gill Industries and Peiker Acustic (no spelling mistake here). By June 2013, Intel had also thrown its weight behind A4WP. A4WP’s Board of Directors by then also included Broadcom and IDT.

In Dec 2013, the first version of their Rezence standard was released. This was an inductive standard, but as mentioned, the frequency was set to 6.78 MHz, because that is the lowest, almost unlimited frequency band in terms of “intentional” electromagnetic interference (EMI) as described in the international applicable standard known as CISPR 11. Microwave ovens also get a “free pass” in effect, because 2.45 GHz is also permitted by CISPR 11. So do radio-controlled toys working at 27 MHz. And so on.

Rezence is a combination of the words “resonance” and “essence”. It describes a single power transmitter unit (“PTU”) and one or more power receiver units (“PRUs”). This interface standard supports power transfer up to 50 Watts, at distances up to 5 centimeters (“z-freedom”). The power transmission frequency is 6.78 MHz, and up to eight devices can be powered from a single PTU depending on transmitter and receiver geometry and power levels. A two-way bluetooth smart link operating at the standard frequency of 2.40 to 2.48 GHz is also unique to the A4WP system. It is intended for control of power levels, identification of valid loads and protection of, and from, non-compliant devices.

In Feb 2014 WiTricity decided to throw its entire weight behind the similar, evolving standard from A4WP. So, its products also now work at the Rezence frequency of 6.78 MHz not their initial 9.9 MHz.

In June 2014, WiTricity announced an enhanced working relationship with another powerful member of A4WP: Intel. But interestingly, prior to all that, as early as in May 2013, WiTricty, an obvious pioneer of MR-based systems had gone and joined PMA, a supposedly “opposing” MI-based standard. But on second thought, this only emphasizes the fact that though the three standards under discussion here may seem “different” to some people, their underlying principles are the same — Faraday’s law of induction as applied to resonant circuits. The only real difference between MI and MR is the operating point on the resonance curve, as mentioned previously.

Yet, Rezence is different when it comes to its “use-cases”. The major claim to fame of Rezence is that it enables significantly more “z-freedom” (separation), yet at safe frequency levels, unlike microwave power transfer (MPT). Rezence also offers multiple devices to be charged simultaneously on a single transmitter/charging pad.  And it is safe too, based on the same magnetic induction principle.

Many consider the Rezence standard immature when compared to the infrastructure already set up by WPC. Testing and certification labs are just coming up for Rezence. Over the period Dec 2013 to Jan 2014, Telecommunications Technologies Association (TTA) and AT4 wireless (AT4w) became the first Rezence Authorized Test Labs (ATLs).

What about commercialization? In June 2014, Gill Electronics announced a partnership with Qualcomm and in the same month debuted the “first commercially available resonant (Rezence) wireless products” at Neocon 2014. This was a 16W transmitter to be sold under the brand name TesLink. NuCurrent announced their high-frequency resonant antennas were being used in this Tx unit.

Where were the Rezence receiver units though? — many asked. There always needs to be an ecosystem in place, after all. In September 2014, Gill Electronics uploaded a photograph without comment, indicating forthcoming TesLink branded aftermarket sleeves for iPhone 5/5s. Though, clearly this has added significantly to the size of the phone. But that will likely be overcome soon.  

Some of A4WP’s staunch key members include Intel, HP, Dell and Lenovo, none of which have elected to become members of the other two prevalent standards. Perhaps a bit surprisingly, Qualcomm, and even Samsung, founders of A4WP, are currently members of all the three WPT standards.

The current Rezence standard is version 1.2 dated Nov 21, 2013 available from the Rezence website.


Why Not WiPower?

Samsung, Qualcomm start up Alliance for Wireless Power to take on Qi

The Alliance for Wireless Power (A4WP) Announces Its Consumer Brand Rezence


Automotive In-Vehicle WPT

In April 2012, Mopar, a division of Chrysler, announced for the first time, an in-vehicle charger, meant for the Dodge Dart 2013 model. Since then, a number of Chrysler vehicles have come with built-in charging pads. You may need to buy a special case for your phone though. It is however also being mentioned that the Chrysler charging system is compatible with Qi, though the Qi logo is not visible in pictures. In Dec 2012, Toyota announced that its Avalon 2013 will be the world’s first car offering a built-in Qi-charger. And it does seem to have preceded the Dart 2013 just a bit, in becoming the world’s first car available with in-vehicle charging.

On the other hand, GM, despite having invested millions into Powermat Technologies, and working steadily with them for years, specifically to add in-vehicle charging to the Chevy Volt, has been relatively slow to adopt. In July 2014, they finally announced the Escalade would be the first GM vehicle to have in-vehicle PMA charging built in, around Fall 2014, while other models would follow soon. Surprisingly, as previously mentioned, it seems that Visteon is behind this effort now.

There are lingering safety concerns about putting WPT inside cars. Interference with car electronics can be hazardous. For example, a remote keyless system (RKS), or remote fob, performs the functions of a standard car key, but without physical contact. When within a few yards of the car, pressing a button on the remote can lock or unlock the doors, and may perform other functions. For example, it may even open the door locks without having to press any button on the fob.

A remote keyless system can include both a remote keyless entry system (RKE) to unlock the doors, and a remote keyless ignition system (RKI), which will start the engine on the press of a pushbutton inside. Now consider this: what if a WPT system caused enough interference to cause issues with such systems. Keep in mind that smart FOBs/smartkeys work at the following two frequencies: 125 kHz and >300MHz (315 MHz for North America-made cars and 433.92 MHz for European, Japanese and Asian cars). One hopes that will not end up contributing to the already growing signs of a “technological backfire” as calls it:

“While technological failures play a role here (the inability of these systems to accurately sense the key fob’s location is really the heart of the problem)… While the resulting tragedies can’t be directly tied to design flaws or vehicle defects, they are yet another indicator of the unforeseen consequences that often accompany technological "advancement.".. With multiple lawsuits pending between consumers and automakers, it will likely take years to unravel who is at fault. In the meantime you can bet automakers will be re-evaluating keyless start and driver behavior to quell this latest technological backfire.”

The most concerning cases are the complaints concerning sudden loss of power and resulting injuries or deaths. Perhaps in response to such concerns, in March 2014, PMA announced that with it will “expand features of its automotive specification to standardize wireless charging requirements beyond what is currently available in the market. This specification, spearheaded by Triune Systems, will offer OEMs a more comprehensive set of features. The automotive specification will incorporate multi-coil implementation for greater spatial freedom, alternative frequency ranges and reduced emissions to prevent interference with other vehicle systems.  It will also incorporate advanced architectures for better efficiency and field upgradability – designed to keep pace with potential future requirements.” Keep in mind that in Oct 2012, WPC had already announced guidelines for aftermarket chargers for use in the automotive environment.   


Powermat Launching in 2015 Cadillac ATS

Toyota’s 2013 Avalon to Offer World’s First Application of Qi Wireless In-Car Charging

Visteon Debuts Wireless Charging on 2015 Cadillac ATS

Is Keyless Start Another Technology Backfire?

Power Matters Alliance (PMA) Announces Advanced Specifications for Wireless Charging in Vehicles

WPC Sets Specs For Wireless Charging In Vehicles

Modern WPT Standards

Here is a quick summary of where we stand today. In industry parlance, the relatively “safe” methods of WPT evolving today are sub-categorized as “MI” or “MR” techniques. MI stands for magnetic induction, whereas MR stands for magnetic resonance. Here are the three competing standards (See Figure 1).

MI-based WPT: The Qi (pronounced “chee”) standard: From the Wireless Power Consortium (WPC) established in Dec 2008. The operating frequency is ~100 to 200 kHz. For ~5 W (output) receivers at the moment. Planned upgrade to ~ 15 W receiver outputs next, with an eventual target 120 W.  One transmitter per receiver typically. Released version 1.1.2 is available at the Wireless Power Consortium (WPC) website

MI-based WPT: The PMA standard:  From the Power Matters Alliance group, established in March 2012. The operating frequency is ~200 to 300 kHz. Released version 2.0 is available at the Power Matters Alliance Group website  (membership required).

MR-based WPT: The Rezence (pronounced “reh-zense”) standard: From A4WP (Alliance for Wireless Power), established in May 2012. Its operating frequency is 6.78 MHz. (This is planned to be eventually merged into the PMA standard; more on that later). Initially for ~3.5 W and ~6.5 W (output) receiver categories, and 16 W and 22 W input transmitters respectively (each transmitter can support multiple receivers). Released version 1.2 is available at the Alliance for Wireless Power Rezence website (membership required).

Does it really matter that A4WP and PMA have “come together”?

On Feb 11, 2014, A4WP and PMA announced that their two associations had signed an agreement aimed at establishing global interoperability of their heretofore distinct standards.  Lest this lead to a lot of excitement about convergence of the standards, the reality check is best stated in The Verge:

“Technically, it’s a little bit more complex than that. According to the presidents of both alliances, the PMA and A4WP aren’t completely merging their organizations, and they also won’t necessarily be combining their two different charging methods into a single brand like Rezence quite yet. They’ve simply come to the conclusion that each group had a piece of the puzzle that the other needed. The PMA gets the A4WP’s so-called resonant wireless charging spec, which can wirelessly charge several gadgets at once, and without requiring them to be oriented in any particular direction on a charging pad. The A4WP gets the PMA’s legacy inductive charging tech, plus cloud-based software infrastructure for managing and monetizing charging points, which could direct smartphone users to the nearest charging hotspot when they’re low on juice, and allow Starbucks to let its customers top off those devices with the purchase of a latte.

What both parties get, though, is a leg up on Qi. Originally, the Wireless Power Consortium’s Qi standard was the front-runner in wireless charging — attracting device manufacturers like HTC, LG, and Samsung to build phones and tablets with the tech — but over the past couple years the PMA and A4WP have attracted a host of supporters, including Intel, AT&T, Starbucks, McDonalds (via PowerKiss), and The Coffee Bean and Tea Leaf. Qualcomm and Samsung have been playing the field, presumably hedging their bets, but both are founding members of the A4WP. WiTricity, the MIT spinoff that invented resonant wireless charging, is now an A4WP member as well.

"The stars are beginning to align for wireless charging tech"

The competing Wireless Power Consortium hasn’t been sitting idly, mind you, inking deals with PowerbyProxi and Texas Instruments to build its own resonant charging solution, and attracting Verizon Wireless and Qualcomm with seats on the WPC board. But even if we’re left with two competing standards bodies, the idea has the potential to snowball now that so many companies are aligned. With upcoming dual-mode devices that support both PMA inductive and A4WP resonant wireless charging, the two cooperating alliances believe the wireless charging market can open up. "Because of the collaboration, you’ve future-proofed yourself going forward," says A4WP president Kamil Grajski. "There’s no reason for anyone to hesitate any longer."


Two alliances team up to win the wireless charging war

The Entry of Magnetic Resonance into the Qi-standard

Knowing that Microwave Power Transfer (MPT) offers signification spatial freedom, albeit at potentially significant environmental cost, that technique was largely ignored in this article. In contrast, both the MI-based standards, offer x and y freedom (off-center spatial freedom) of typically 5 mm, whereas the z-freedom (vertical separation) is only about 2 to 3 mm (measured from the transmitter coil surface).  In contrast, MR-based units (e.g. Rezence) potentially offer greater spatial freedom (even more z-freedom), and that is the main reason for the increasing attention in this relatively still immature technology. But some recent reported experiments offering 30 to 40 mm of z-freedom in Qi-compliant systems have spurred interest further. Back in June 2011, Fulton Innovation had already demonstrated up to 40 mm “z-freedom” by using WPC-compatible magnetic resonance (“MR”) technology. The new draft standard v1.2 of Qi is expected to address MR.

So, MI has finally entered the MR domain, albeit at a much lower frequency than Rezence. It could run into EMI problems though, because it does not use CISPR 11’s “intentional” EMI bands mentioned previously. But special techniques are being developed to overcome that.

This takes us to an interesting statement which was included in the April 2012 newsletter of WPC while announcing the Qi 1.1 specification.

“At this moment 6 additional transmitter designs are under review. One of these 6 transmitter designs uses magnetic resonance techniques to transfer 5 Watt into a Qi receiver through a 40 mm table top”. That was indeed interesting: a resonant transmitter powering a Qi receiver, producing 40mm of “z-freedom”.

This implies a certain degree of backwards compatibility and interoperability too, though it was not fully clarified at the time.

In June 2014, at Computex, a New Zealand company, PowerbyProxi, currently being funded by Samsung among others, demonstrated a resonant charging bowl for 7.5 W and also, a 15 W transmitter unit offering 30mm z-freedom. This was Qi-compatible. PowerbyProxi claims over 200 patents and was formed out of IP developed for the past 25 years at the University of Auckland.

In Oct 2014 this was on the wire:

“ConvenientPower unveiled today the Tx R2 and Tx R3 resonance charger series, the Tx R2 being the world’s first resonant platform enhancing the recently approved Qi wireless charging A27 specification. The new generation of resonance wireless charging solutions include the first commercialized intelligent continuous charging through varying distance of up to 30mm coil-to-coil which is enabled through a Qi compliant charging platform, the newly approved Qi v1.1 A27….The first to be designed to wirelessly charge Qi devices or receivers in the market, the Tx R2 is Qi compliant up to 5mm and Qi compatible up to a charging distance of 20 mm. The newly approved Qi Addendum A27 underpins the Tx R2 extensions enabling resonance charging. ConvenientPower is the first to launch resonance charging through the Qi Addendum A27, the new power transmitter description offered in the Qi v 1.1 specification. The Tx R3 resonance charger features uniform charging across the charging surface and distance up to 30 mm, with the device placed in any direction and location. Wireless charging at up to 35 degree angle while delivering competitive efficiency levels are also key features of the resonance series”.

In other words, new MR-based receiver and transmitter units are being rapidly released, and they are going to work, albeit with lesser z-freedom than Rezence systems, and far less than MPT of course, but will be backwards compatible with traditional Qi-certified units.  This once again highlights the fact that the physics behind MI- and MR-based WPT methods is actually the same: Faraday’s law of induction.


PowerbyProxi pushes wireless power frontiers

WPT Members and Ongoing Turf battles

In Figure 4 we can see the battle of the standards at play, and their membership map, as of Nov 10, 2014. Here are some conclusions:

Of the 212 members of WPC, only 9 + 33 = (20%) have decided to join PMA too. Also, of these, a few are just test houses. Verizon is a strong (staunch) backer here.

Of the 68 members of PMA, 9 + 33 = 42 (62%) are also members of WPC. In terms of percentage, that is 62% versus 20% from a) above. This may indicates a higher confidence level in the Qi-standard overall. However, AT&T is staunchly backing this particular horse.    

Of the 121 members of A4WP, 19 + 33 + 6 = 58 (48%) are also members of the two MI-based standards. This seems to indicate the battle lines are not as sharply drawn as some may think. However Dell, HP, Intel and Lenovo are backing this one alone, most likely spurred by the possibility of additional z-freedom, which is clearly very helpful for charging laptops, tablets etc, especially while they are still being used and operated.

Giants like Samsung and LG are members of all three associations.

A notable omission is Apple, but they clearly have the power to forge their own proprietary standard.   Time will tell what exactly that is. In Sept 2013, the sale of a current staunch member of WPC, Nokia, to Microsoft Mobile, was announced. There have been some defectors too. In May 2013, PowerKiss, a hitherto prominent European supporter of Qi, was acquired by Powermat, and thereby defected to PMA. Just a few months ago, McDonalds was busy testing PowerKiss’s Qi-based chargers for possible induction into select European restaurants. Since then, McDonald’s has apparently gone the PMA way. Along with Coffee Bean, Tea Leaf and Starbucks. However, In Nov 2014, Marriott  Hotels announced they would be making available (only) Qi transmitters on their properties. And so on. The battle of the standards continues.

The Most Cautious Companies?

As per Figure 4, there are 33 companies or organizations which seem to be watching the emerging situation with extreme caution, and have taken up membership of all three standards. These understandably include safety testing houses like TUV and UL and several semiconductor vendors such as IDT, Texas Instruments, Fairchild, SGS, Samsung and Maxim, but also some big names such as Qualcomm, Samsung, LG, HTC, ASUSTek, Microsoft, Toshiba and Sony. There are also 234 companies, over 2/3rd of the total 301, who have expressed absolute faith in only one standard. So the battle lines are drawn very distinctly.  

Figure 4: The breakup and overlap of the members of WPC, PMA and A4WP.

Current Cell phones with Native Support for the Standards

Finally, we review the end-purpose of modern WPT: cell phones. Where are we poised?

There have been aftermarket phone jackets available for some time now, offering to add on wireless charging to phones. But only recently have phones with built-in support for WPT started appearing. At this moment for example, the following phones offer the possibility of native Qi support: Nokia Lumia 920, HTC 8X, Droid DNA, Rzound, Incredible 4G LTE, Google (LG) Nexus 4/Nexus 5, LG DIL/LTE2/SHARP SH-13C/SH-O4D/SH-O7D/SH-02D. Predictably, these are available as such on Verizon, which is a staunch WPC member, not a PMA supporter. The same phones may be available on AT&T, but either with wireless charging completely disabled, or a thick aftermarket jacket offering PMA support. For example, even though AT&T advertized the Lumia 920 as supporting wireless charging, in reality, they had “neutered” the original phone. They also released the Lumia 920 as a variant called the Lumia 1520 with wireless charging disabled, which then triggered clever hacks to restore the built-in Qi capability.

In contrast, Kyocera is currently a member of PMA, not of WPC. Expectedly, since May 2014, Sprint and Virgin Mobile US have both been offering the Kyocera Hydro Vibe with PMA wireless charging built in. In June 2014 Kyocera launched its PMA-enabled Hydro Icon with Boost Mobile. Finally, in Nov 2014 the rugged Kyocera DuraForce was released on AT&T network, also with PMA support only. However, Kyocera has silently been serving the Qi (WPC) market too, through Verizon.  The Kyocera Hydro Elite (C6750) and the Kyocera Brigadier (E6782) both from Verizon, were released in Aug 2013 and Oct 2014 respectively.

It is well-known that AT&T has consistently removed Qi capability from Nokia phones, to enforce the PMA standard instead. As recently as Oct 2014, it was being widely reported that AT&T had finally relented, and that on Nov 7, 2014, the Nokia Lumia 830 would be released and would feature a dual-use Qi+PMA capable receiver. However, as of today, though the 830 has indeed been released as scheduled, the technical specs of the phone on AT&T’s site makes no mention of any support for wireless charging.

So far, as we can see from Kyocera’s case, neither has Verizon been releasing any PMA-based phones.

There certainly are no Rezence phones around yet, and perhaps will not be in the near future. However aftermarket Rezence phone jackets from TesLink (Gill Electronics) seem to be coming, as mentioned previously.  In general, Rezence is finding favor more for its ability to charge bigger devices such as tablets and laptops. The future will be clearer soon.


Nokia Lumia 920

Here’s how to get Qi wireless charging back on your AT&T Nokia Lumia 1520

The Waterproof Kyocera Hydro Elite

AT&T removed Qi wireless charging in the Lumia 1520 to make room for PMA

Qi Wireless Charging

AT&T Lumia 830 comes with dual-use Qi/PMA wireless charging covers in green, black



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