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WPT breaks all connections, Part 2

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By eeNews Europe


Inductive Automotive Wireless Chargers
 
Doing a patent search we see that some of the earliest patents on wireless (inductive) charging were applied for by Hughes Aircraft Company in 1992.  Seems a strange choice, but this is how it played out :- In the mid-90s, Hughes Electronics, a subsidiary of Hughes Corp., released the Magne Charge interface, which was used for the first electric vehicles made by both General Motors (GM) and Toyota. Magne Charge was initially manufactured by the GM subsidiary called Delco Electronics. Note that this powerful yet spatially flexible wireless power transfer technology was inductive, not MPT-based. It operated between 80 to 350 kHz and consisted of a paddle containing the primary coil, about the size of a table-tennis (ping-pong) bat, which was inserted into a slot in the car for delivering up to 6.6 kW — without metal contacts, and with an impressive efficiency of 86%. This is still used by a few hundred first generation Toyota RAV4 EV electric vehicles. But as these retire from the road, Magne Charge will become obsolete.

The 2012 Gen 2 RAV4 EV, as well as the Nissan Leaf and Chevrolet Volt, use the new non-wireless SAE J1772 standard instead (it needs firm metal connections). The “older” Magne Charge wireless system is now referred to as the J1773 system.

Note that an older inductive patent was filed in 1975 too. See references below.

References

Electromagnetically coupled battery charger

Electric vehicle inductive coupling charge port

Battery charging system
 

Giving Teeth to Modern WPT

In the late 90’s, the basic induction principle behind inductive WPT found its way into homes through the strangest route: tucked away deep inside Braun’s latest Oral-B electric toothbrushes. Braun was part of The Gillette Company from 1984 to 2005. In 2005, Gillette along with Braun was acquired by Proctor and Gamble (P&G), making the latter the world’s largest consumer goods company. At almost the same time, rechargeable toothbrush technology appeared in the Sonicare brand from Optiva too, which was acquired by Philips in 2000.  These gadgets abound in homes today. However their form factor is clearly very different from what is considered acceptable or helpful for charging mobile phones. But the basic principle is the same. It is Faraday all over again.

References

Charging coil core insert for electric toothbrushes

Rechargeable toothbrushes with charging stations

Have a Heart

A Massachusetts-based company called AbioMed also pioneered inductive WPT at an early stage. They developed AbioCor, an artificial heart which could be fully implanted within a patient, due to a combination of technological advances in miniaturization, biosensors, plastics and energy transfer. The AbioCor ran on a rechargeable battery, charged by a “transcutaneous energy transmission” (TET) system. This was an under-skin transfer of power. There were no wires or tubes penetrating the skin, and therefore no risk of infection on that account. The aim of such systems is to transfer power across modest separations of 10-25 mm typically. On July 2, 2001, the first patient ever received the AbioCor.  By September 2004, 14 patients had received it — Faraday to the rescue once again.

Cleansing and Purification

A company called Splashpower was founded in 2001. It was a spinoff of Univ. of Cambridge UK. In Oct 2002, it announced its intention to soon release mobile phone and mp3 player wireless chargers in the form of a “transmitter” unit called “SplashPad” costing about $100. To pair up with the SplashPad, a “SplashModule” dongle costing ~$20 could be purchased as a “receiver” and plugged into a cell phone for example. But the development ran into a lot of unforeseen design problems and the commercial release got stalled for years. This should be an indication of the fact that these “mundane” wireless charging methods are in fact tricky, and are still being properly understood. Certainly, resonance is tricky business.

Splashpower filed several patents in inductive charging before they declared bankruptcy in April 2008. They were quickly purchased a month later by Fulton Innovation, a subsidiary of Alticor, the parent company of Amway, among others. With the help of Fulton Innovation, Splashpower wireless products did see the light of day in Aug 2008. They were then quickly reviewed by Gizmodo among others.

However, even prior to the Splashpower takeover, Fulton Innovation had been steadily working on developing their “eCoupled” technology of wireless charging. On April 6, 2008, they announced they would soon be releasing Amway’s bestselling portable water purifier called eSpring, with a wireless charging system based on Fulton’s eCoupled technology. That purifier was surprisingly the major impetus behind modern WPT. “eCoupled” was the underlying technology of the Wireless Power Consortium (WPC) to be founded very soon thereafter.

Note: The head office of Alticor is listed as 7575 Fulton Street East, Ada, MI 49355-0001, USA. So we can easily surmise where the name Fulton came from. But Fulton Innovation should not be mistaken for Fulton, a group of companies making boilers etc.  


Breathe in the Air: Says WPC

On Nov 26, 2008 Fulton Innovation released “The Base Spec: Low Power Specification Guide for Partnered Product Development, Revision 0.9”.  Buoyed by the acquired intellectual property of Splashpower, and in an attempt to replicate the success story of the Wi-Fi Alliance formed in 1999, Fulton Innovation founded the Wireless Power Consortium (WPC) in Dec 2008. In the process they partnered with seven others: ConvenientPower, Logitech, Philips, Sanyo, Shenzen Sang Fei Communications, National Semiconductor (now Texas Instruments), and Texas Instruments. In Aug 2009 they published the now well-known Qi standard, version 0.95. A month later they released version 1.0. By then WPC already had 55+ members.

The first formalized MI-based WPT standard was thus born. It works at around 100-200 kHz. Its name, “Qi” (pronounced chee) was based on traditional Chinese culture: Qi is frequently translated as “natural energy”, “life force”, or “energy flow”. Its literal translation is “breath” or “air”. The standard is limited to delivering up to 5W at this moment.

In April 2012, version 1.1 was released. New to this version were many more transmitter specifications — up to 12 now. Also, increased sensitivity in another crucial area called “foreign object detection”, or FOD. Its purpose is to avoid metal objects inadvertently placed on the transmitter from getting too hot and posing a fire hazard or causing bodily harm. Also included in the revised standard was the possibility to power transmitter units with a USB port instead of a traditional AC-DC wall wart.

As of Nov 10, 2014, WPC had grown to 212 members, and the most current version, v1.1.2 dated June 2013, was available for download from Wireless Power Consortium. Some of WPC’s staunch key members include Ikea and Verizon, besides Fulton Innovation of course, none of which have elected to become members of the other prevalent standards.
 

The Earliest Commercially Available Phone Chargers: PMA

 
An Israeli startup called Powermat Technologies Ltd. was founded in 2006 by Ran Poliakine, CEO, and Dr. Amir Ben Shalom in 2006 for the explicit purpose of designing and selling wireless power transfer products. Its first products were displayed at the Consumer Electronics Show (CES) of 2009. In one demo a receiver jacket was slipped on a Blackberry phone and placed on a transmitter base (“mat”). These units were launched shortly thereafter and were sold initially through retailers like Best Buy and Walmart. Later, in an effort to expand, Powermat teamed up with Procter & Gamble (P&G), well-known for its Duracell brand of batteries.

Duracell was already in search of a better solution. It had been selling its version of “wireless” charging mats (called “MyGrid”) and receivers (“PowerDisc”) since 2009, using technology it had licensed from a company called WildCharge Inc. That product still sells on Amazon, but it is considered “finicky”. It turns out that this was not a “wireless” solution in the sense we are discussing here.  Gizmag says:

The WildCharge itself is simply a pad around the size of a mousemat with conductive metal strips running across it. This must be plugged into the mains using the supplied adapter, but unless you pick up one of the available bundles, you’ll need to then invest in a compatible adapter for the device(s) of your choice. The reason for this is that there doesn’t appear to be inherently anything fancy about this type of conductive charging solution. Power travels through the strips on the pad itself to an adapter, which must make metal-on-metal contact to the power port of a handheld….As it turns out, exactly what type of handheld you have makes significant impact on usability and convenience. The ideal situation, provided you’re happy to smother your shiny new gadget in such a way, is to use a "skin" that encompasses the charge terminals. Currently these are only available for the iPhone and iPod touch, Blackberry Curve and Blackberry Pearl.

As mentioned, in January 2005, P&G had announced the acquisition of Gillette, forming the largest consumer goods company in the world. They had thereby added brands such as Gillette razors, Duracell, Braun, and Oral-B to their repertory. Oral-B wireless charging technology for toothbrushes was already known to them. As a result of their common goals and interests, in September 2011 Duracell and Powermat Technologies Ltd. formed a joint venture, 55% owned by the latter, called Duracell Powermat. The Power Matters Alliance (PMA) was founded by both Powermat Technologies and Duracell Powermat in March 2012.

PMA released the version 2.0 of the PMA standard (or specification) in April 2014. It is available to members from Power Matters Alliance. As of Nov 10, 2014, PMA had 68 members compared to 212 in WPC. Note that in Oct 2014, P&G announced they would be spinning off Duracell. The very next month, Warren Buffett announced he was buying it.
 
References

Wildcharge review – is wireless power worth it?


For Better or for Worse?

We may ask: Is PMA technology or standard any better, or worse, than the Qi standard from WPC? As if to answer that question, the CEO of Duracell Powermat was interviewed in July 2013, and excerpts of that interview are presented below. The views however, are his entirely, and obviously not unbiased.

Ron Rabinowitz, CEO of Duracell Powermat, which formed the PMA, said that the real promise of wireless charging lies in true ubiquity:

The name of the game is not the accessories we’re selling and the mats. Those are very important, but the real game changers are the wireless charging hotspots in public places.

Duracell Powermat was on board with the WPC’s Qi standard, but Rabinowitz said that his company preferred a different strategy. While he agrees that a standard is a necessity, Duracell Powermat has found more fruits in working directly with partners that will expand the public infrastructure. Rabinowitz continues:

When you have an organization that is doing a very poor job—I’m talking about the WPC—and that is focusing on the lowest common denominator of just the spec itself, it’s good but it’s not enough. We tried to work through WPC, but we found it much more efficient to work closely with partners like Starbucks, AT&T…

In reality, these two competing standards are almost identical. For example, Qi operates inductively over the frequency range of about 100-200 kHz, whereas PMA operates over about 200-300 kHz.  That is hardly significant in terms of the entire spectrum shown in Figure 2. Clearly, WPT alliances are being driven largely by business interests and royalties, not technology. But the ongoing battle is certainly fierce, and the outcome unknown. And there was another contender too, as discussed next.

References

Wireless charging and a tale of two standards
 

What Happens in Vegas Doesn’t Always Stay There
 

The Consumer Electronics Show (CES) is held annually in Las Vegas in January. In recently years, it has been home to several memorable demos of WPT, which are now changing our world.

At CES 2007, the CNET award for Best Emerging Technology was won by an unlikely entrant called Powercast. Unlikely, because it actually used microwaves (MPT) all over again, not induction.   Beams of radio-frequency (RF) energy at 915 MHz were transmitted and harnessed at a large distance. To comply with safe limits however, the power was kept very low indeed. At best, that amounted to providing a constant background “trickle charge” to extend the battery life of any cell phone, not a full zero-to-max charge in one hour, as is usually expected today. Further, as the company website reveals, their products are certified to work legally only in the US and Canada. However, interesting things are certainly possible with this approach, such as a wireless Christmas tree, or powering Zigbee transceivers. Powercast continued to demo its interesting products at CES 2008 and CES 2009.

Keep in mind that Powercast is a member of another relatively small consortium, called WiPoT, or just Wireless Power Transfer consortium. Their ultimate aim is closest to Tesla’s vision for all mankind. Instead of a world wireless system however, WiPoT talks about a “ubiquitous power source”. Of course the allowable power levels would make Tesla cringe.

At CES 2007, a company called Visteon, a spinoff of Ford Motor Company and often considered the Ford equivalent of General Motor’s (GM’s) Delphi, demonstrated a proposed in-vehicle charger. This was based on the eCoupled technology from Fulton Innovation. Notice that this event preceded the formation of WPC in 2008, but in effect this was a Qi-based charger.

As mentioned, Powermat Technologies demonstrated their products two years later at CES 2009, and released their products commercially a few months later in 2009 itself. Theirs was in effect a PMA-based charger.

Fast-forward a few years later, surprisingly, Visteon, not Powermat as widely expected, is now behind the multi-standard built-in car charger in GM’s 2015 Cadillac ATS, due to be released in the summer of 2015.  This would also likely be one of the world’s first true commercial dual-mode mobile transmitter pad (as opposed to just a dual-mode chip) — supporting both Qi and PMA receivers.

At CES 2009, Fulton Innovation went a step further, and demonstrated a modern kitchen countertop, based on its eCoupled technology. A blender was shown working wirelessly.

At CES 2009, Palm Inc. (later acquired by HP) also announced that their new “Pre” smartphone on display would soon be available with an optional inductive charger accessory, the "Touchstone".  Indeed, the receiver jacket and transmitter pads were released shortly thereafter. The first Amazon reviews of the Touchstone were posted in the last week of June 2009, giving us an idea of its availability. Since then, many tried to use/hack that particular wireless charger for use inside their vehicles.

CES 2009 in particular, was clearly a very happening place for WPT! In fact another company called Powerbeam revealed an optical version of WPT, where beams of infrared energy carry forth significant amounts of energy to photovoltaic cells which then harness the energy. This was of course useful only for perpetually fixed objects such as wireless picture frames etc. Safety issues were resolved in an interesting way.

The two dominant standards discussed so far, Qi and PMA, are both considered “MI-based”. MI stands for magnetic induction. Shortly thereafter, “MR-based” WPT also came along, largely through academia. MR stands for magnetic resonance. An early peek at that technology was also available at CES 2009, from a company called WiTricity, discussed further below.

A year later, at CES 2010, a company called WiPower also did an MR-based WPT demo, and was acquired the same year by Qualcomm. That was the birth of the A4WP (alliance for wireless power) which later introduced the Rezence standard (see Figure 1). This standard is now expected by many to become the dominant one, based on its promise of greater separation between transmitter and receiver, and also its ability to charge multiple devices simultaneously, on one transmitting surface. It is also considered biologically safe since though its frequency of 6.78 MHz is much higher than for the MI standards (Qi and PMA), it is still much less than microwaves. This issue was discussed previously. The chosen frequency also gets a “free pass” through regulatory electromagnetic interference (EMI) limits, and it also significantly reduces FOD issues. So, coins or keys placed inadvertently on the high-frequency transmitter surface, do not overheat — thanks to the much smaller skin depth at 6.78 MHz.    

Note: Despite the buzz, MI and MR differ only in the operating point on the resonance curve. MR systems exploit deep resonance to achieve higher separation between transmitter and receiver — typically a few cm, compared to the few mm from the MI standards Qi and PMA. Neither of them matches MPT in this regard, but since both are based on Faraday’s Law of magnetic induction, they are considered biologically safe.

References

Harvesting RF Energy

[CES 2009] PowerCast Wireless, Contactless Power

Visteon Unveils its Latest High-Tech Innovation

Visteon Debuts Wireless Charging on 2015 Cadillac ATS

eCoupled Wireless Blender Demo – Fulton Innovation


Electric Light Bulb Lit by WiTricity

In 2006, Marin Soljačić (pronounced soul-ya-cheech), an assistant professor at Massachusetts Institute of Technology (MIT) talked about his vision for wirelessly charging cell phones, apparently to avoid the insidious beeping that had reportedly been keeping him awake at night as the battery died. The MIT project was named WiTricity.

In 2007 the team successfully transferred 60 W over a distance of 2-m, turning on an electric light bulb. This was roughly 116 years after the fateful day when Tesla had “already done it”, as some still want to believe. And this was the birth of “MR”. Marin’s technique used a frequency of 9.9 MHz and was 45% efficient. It was also household safe, unlike MPT.

The name of the MIT project was WiTricity, and the research project eventually got spun off into a private company with the same name, i.e., WiTricity. As mentioned, WiTricity demonstrated at CES 2009 in January. The company’s CEO, Eric Giler did another interesting demo in July of the same year, at TED Global Conference held in Oxford. Using a large transmitter coil, he created an immersive magnetic field in which he turned on a TV and charged several cell phones by just holding them several feet away in air from the coil. It may look a bit similar to the newspaper account of Tesla’s hand-waving demo in 1891, but as mentioned, that was a static electric field, whereas this was a varying magnetic field.   
Sponsor video, mouseover for sound
 
In April 2011, WiTricity and Toyota Motor Corporation (TMC) announced a new wireless charging alliance.  In Dec 2013, a formal partnership with Toyota was announced, for a proposed vehicle such as Prius, with wireless charging, expected in 2016.

This is Part two of a three part article. Part one was previously published.

References

Wireless energy could power consumer, industrial electronics

Goodbye Wires!

A demo of wireless electricity

TMC and WiTricity Form Wireless Battery-charging Alliance

Toyota will license WiTricity wireless charging tech for upcoming EVs


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