PowerbyProxi has been in the wireless power business for just over 9 years (that’s if you don’t count many of our individual backgrounds with the University of Auckland). 9 years is a substantial amount of time as a company, because the industry itself is still very young. Consider that the Qi specification, which continues to make giant strides to becoming the default standard for wireless charging, was only established in 2009. Other standards groups including the Power Matters Alliance (PMA), The WiPower Alliance, which became the Alliance for Wireless Power (A4WP) and then AirFuel) were not formed until 2012.
The point I am trying to make is that we have seen a lot of developments in wireless power and understand the vast challenges in bringing the technology to commercial reality. We have remained successful during this time, partly due to a mix of some very bright engineers, and a focus on working hard to develop real, working solutions for our customers with a deep understanding on fundamentals. No wireless trickery and showy demos that cannot be commercialized here!
Over the past few years we (the collective public) has witnessed the development of a number of technologies which propose the transfer of power over vast distances, via various matters i.e. ultrasound, and RF. Such technologies promise features such as extensive transmission distance and safe power transfer well beyond the extent of traditional inductive or resonant technologies. For those people considering any sort of wireless power solution, I want to talk directly to you. I want to provide you with the means and tools required to be able to help you come to your own conclusions about the suitability of the various approaches.
This toolset takes the form of a series of questions you should be asking yourself and your proposed wireless power technology supplier. These questions are based on our experiences and the challenges we have faced during our 9 years developing a range of industrial and consumer electronics solutions for customers.
Let’s begin with the basics:
Essentially the ICNIRP determine specific guidelines on the health hazards associated with radiation exposure for certain technologies.
Therefore, based on which type of wireless power transfer technology you are considering;
It may not always be easy to track down the performance of some of these technologies vs. these limits, therefore ask the company to provide a technical analysis of their wireless power solution in relation to the ICNRIP guidelines.
If they are unable to provide a technical analysis, then ask why not?
Now for your own consideration….
We find that for most people, the top priorities will include a selection of the following: Power Level (charging speed), Distance, Spatial freedom and Interoperability with existing products. Does that sound about right?
From our experience, Safety, EMC and increasingly Efficiency are non-optional top priorities that block the ability to ship product. Therefore the next question to ask is:
If you have been reassured that safety, efficiency and EMC are not a concern, then that’s fantastic. But just to be sure, its best to double check on this, because it is a notoriously tough balance between power output/transmission distance/EMC performance/safety/efficiency.
..and one more (necessary) check…
If it all checks out, then it shouldn’t be too much hassle for them to let you do some tests yourself, right?
Efficiency is crucial in determining the overall performance of the system. It directly impacts overall charging speed and transmission distance by examining power loss from the power source to the receiving device. Not to mention, it provides a good gauge about associated emissions.
Now be careful here – an age-old trick is to provide efficiency figures for the ‘sweet spot’ of the system, which isn’t characteristic of the whole system. So make sure you ask…
And if they don’t know what the best and worst case scenario is, then find out, why not?!
There is no reason why any of this information should be made unavailable to you, the customer. Furthermore, you should never be denied the opportunity to test the system independently.
By being able to clarify each of these questions, you will be able to understand exactly what the proposed system is capable of and how ‘real’ or commercially viable the technology actually is.
So the next time you are thinking about a wireless power alternative, make sure you don’t get caught up in the hype – do your due diligence and make sure the respective company can back up their assertions with real data.
Wireless power has made significant advancements in the last few years with many inductive technologies becoming mainstream and widely available – notably Qi and PowerMat products. Major players like Samsung are building wireless power receivers into their phones along with a huge number of transmitters widely available from companies like AirCharge, TYLT and of course Samsung themselves. Currently there are nearly 700 different products on the market that are Qi certified alone.
However, inductive wireless charging is not without its limitations – amongst them include slower charging speed and the requirement for precise alignment of the receiver (smartphone) and transmitter (wireless charger). This is where resonant technology can deliver a number of advantages and truly represents the future for charging wirelessly. Unlike inductive technologies, there are still zero finalized resonant products in the marketplace. A4WP has long promised an option and now the Wireless Power Consortium is in the process of developing a resonant specification called Resonant Qi. I’ve been working on the specification personally along with other top member companies at the WPC. The new Resonant Qi specification will overcome existing limitations with Inductive Qi and provide those consumer benefits which OEMs are looking to integrate into their devices.
What’s most important?
The discussion on how inductive and resonant perform must be framed in respect to what is valued by the end user. Specifically, what are the factors that will increase the appeal of wireless charging for the consumer?
Based on the above factors, how do inductive and resonant technologies stack up?
I have used examples of current inductive products that we find on the market today (Qi and PMA) to compare functionality and performance with the Resonant Qi specification, currently in the works – see Table 1 below:
Overall, resonant presents a wireless charging future with greater convenience, performance and flexibility. The main areas where we will see the greatest advantages are:
Resonant Qi technology provides the next evolution to an already widely available set of products. It will provide a noticeable step-up in performance over the current inductive solutions, and will help wireless charging technology become more pervasive. Today, inductive solutions continue to be the only option for consumers wanting to purchase their own wireless charging system despite a lot of noise from other rival resonant standards. One has to ask why there are no (zero!) A4WP products shipping in the market to date.
The key for the WPC, and arguably the industry at large, will be to deliver a Resonant Qi specification that remains fully compatible with the hundreds of millions of existing Qi products on the market, while also delivering greater user performance over inductive systems. This approach puts the consumer first, and the best technologies always do.
It has been an incredibly exciting start to 2015 with several major announcements in wireless power along with several noticeable absences…
Just last week we saw the first major smartphone manufacturer (major by market share) embed wireless charging into their flagship device. Samsung has decided to build in the WPC’s Qi technology into their flagship Galaxy S6 and S6 edge device. Qi wireless charging will be supported out of the box by Samsung for the first time. These new smartphones will also support PMA. This is sometimes called “dual-mode.” As a WPC steering group member this is great news. You may be surprised to hear me say that, but it really is.
What it means is that companies making a significant investment to deploy infrastructure in coffee shops, cars, airports, home furniture and so on, can make those investments with confidence. There is no longer any fear or uncertainty regarding which standard major smartphones will adopt.
These dual-mode phones are and will continue to drive demand for Qi transmitters. It’s not hard to see why. Qi caters to the widest range of applications and offers a clear path forward to resonance whilst guaranteeing full backwards compatibility. Brands like IKEA, AirCharge, McDonalds, Chargespot, Marriott, Toyota to name few are all choosing Qi transmitters. That’s right – Qi only transmitters. In fact, there are over 682 Qi certified devices today.
The WPC called out a few key stats in its recent Press release:
With the Samsung Galaxy S6 joining the Qi club, today almost every single smartphone manufacturer (except Apple, Levono and Xiaomi) has a flagship device with Qi wireless charging built in. This includes LG, HTC, Google Nexus, Microsoft and Motorola.
Aircharge’s recently launched app is a great way to find Qi charging spots around the world. It shows that there are over 3,000 locations in a wide variety of locations supporting Qi and this is only the beginning. Businesses are paying to install Qi. To put that in context, the PMA has 200 noted locations –all within Starbucks locations. The noticeable absence of the A4WP camp is also interesting. A4WP has no products in the market to date.
Why then did PMA select A4WP as its resonance path forward given how similar WPC and PMA technology are? As an engineer and technologist, it’s hard to see how PMA and A4WP technologies can result in a single truly interoperable standard. One can always co-house systems, but that’s not a cost effective solution – nor is it likely to fit in a modern day smartphone.
Additionally, you may find it interesting that most of the press seems to have misinterpreted the merging of two standards organisations as the merging of two standards – which it is not.
When we hosted the Wireless Power Consortium in Auckland in January, the Resonant Qi Specification was made available to its 200+ member companies. We were pleased to host the meeting for the second year and contributed a significant amount of our technology, intellectual property and expertise to deliver a highly efficient, backwards-compatible, resonant wireless charging system.
We now we have the world’s first resonant system compatible with the most widely deployed wireless power standard. That’s extremely exciting as it provides companies like Samsung a clear path to Resonant Qi with full backwards compatibility to Inductive Qi.
The advancement includes safety features such as foreign object detection, even with multi-device systems, as well as an industry leading 70%+ total system efficiency for a fast and effective charge.
PowerbyProxi’s new evaluation kit is a single design which supports both Resonant Qi and Inductive Qi modes, providing a clear way forward for the growing number of OEMs who are integrating the WPC’s Qi standard into their smartphones and other devices.
2015 is already off to a fast start and is going to be an incredibly exciting year for wireless power. One that we will look back on as a tipping point in the industry.
Blog first published and contributed to Planet Analog
Blog first published and contributed to Planet Analog
Recent innovations have enabled the creation of robust and reliable wireless power systems that can be tailored for use in a wide variety of industrial and consumer settings. There are two key design considerations when building such a system. One is frequency of operation, which we’ve explored before and will again more in-depth in our next piece. The other is coil geometry.
Coil geometry refers to the design of the transmitter coil (or transmitter coils) that create the electromagnetic field for the transfer of power to the receiver. There are two proven and reliable geometries that are available on the market today — coil array and perimeter coil. Each has features that make it well-suited to certain situations.
A coil array is as it sounds — a collection of small coils placed next to each other in a grid fashion across a flat surface. (Often some sort of charging pad.) The key benefit of a coil array system is that each coil can be individually turned on or off by a special detector circuit. When nothing is near a transmitter, all the coils are off. Placing a phone or other device on or near the transmitter creates a slight magnetic disturbance. That then triggers the coils to scan, determine that a valid device is present (not simply a foreign object like keys or coins), and activate the coil beneath the device.
A perimeter coil is made up of a single large transmitter coil that fills a large area with magnetic current or flux when turned on. Perimeter coils fill the air with flux, enabling 3D charging at very low power levels. However, it is less efficient than a coil array. It’s also not as effective for charging multiple devices simultaneously, or charging at high power levels (>2W).
There is generally a trade-off between coil size, performance, and cost. Coil size and cost are inversely related — smaller coils give a better performance, but at a higher cost. This means that a perimeter coil geometry costs less than a coil array for a given charging area.
Beyond cost, the selection of which geometry to use is based on a variety of considerations, including safety, Z-height, efficiency, and power level.
Safety & EMC interference
The key consideration from a safety perspective is the amount of current or flux that’s released or lost during power transfer. Radio frequency (RF) emissions can be dangerous to human health in excessive quantities, while electromagnetic compatibility (EMC) emissions can interfere with other devices. A coil array design allows individual coils to be turned on, which ensures that the receiver coil — the coil on the device being wirelessly charged — almost always covers most of the transmitter coil. The result is that minimal flux is leaked out. Thus it’s easier to achieve safety compliance as power is scaled up.
It is more difficult to control the direction of the magnetic flux with a perimeter coil. Since it is one continuous coil, flux is not contained to the receiver. Safety testing for EMC compliance in particular becomes difficult with restrictions for the amount of power output that is allowable.
Z-height refers to the distance of power transfer between the transmitter and receiver coils, measured in vertical height. It is particularly important for the integration of wireless power systems into infrastructure where Z-height enables charging through surfaces — think table tops, office desks, or car dashboards.
Both designs enable Z-height charging, but to slightly different degrees. A coil array presents some difficulty — making coils larger to enable greater distance of power transfer can introduce dead spots. (Think of coils like pixels of a TV screen: The more you have, the greater the resolution, and the finer the level of control.) A perimeter coil system achieves Z-height more easily with increased flux — but again, the safety considerations can restrict the amount of output power.
Efficiency equates to the percentage of power lost from the power source to the battery of the device. Higher efficiency means faster charging, responsible use of resources, and overall lower cost (lower power transmitter for a given receiver power requirement).
By energizing specific coils, a coil array provides a better coupling coefficient and thus efficiency. Selective energization of localized coils does not vary significantly based on the position of the receiver on the transmitter. Selective energization also prevents foreign objects — even metal in the receiver device — from getting hot.
A perimeter coil has a lower coupling coefficient that equates to higher power loss — more power is needed to ensure enough is sent to the receiver. Imagine a widespread magnetic field sending out power over the extent of the transmitter charging area. Without selective energization, foreign metal objects may get hot, further reducing efficiency.
Large variations in the induced field depend on the receiver position on the transmitter, which may also result in uneven efficiency across the transmitter, although newer perimeter-coil designs have improved flux-density somewhat. Overall system efficiency is improved if several receivers are placed in the charging area and share the charging energy. In this case, sophisticated communication and control techniques are required to allow the transmitter to recognize the unique receiver requirements and eliminate crosstalk.
One of the key considerations from a design perspective is ensuring that the charging speed of a wireless power system is better than, or at least equivalent to, that of a wired charger. This means different things for array and perimeter set-ups.
Perimeter coil systems are challenged to stay within ICNIRP (International Commission on Non-Ionizing Radiation Protection) limits as power is increased beyond 40W (although this shouldn’t be a factor when powering one or two cell phones). In terms of scalability, a larger pad area will act to lower the efficiency further, thus potentially reducing the power capacity in the center of the transmitter.
Coil-array type systems, because of their higher coupling coefficients, are not as power-constrained. It is easier to scale the power up (beyond 2k watts) without approaching ICNIRP EMI or RF safety limits. This also enables scalability of the transmitter to cover multiple devices of different power requirements and scalability of charging area without sacrificing power transfer efficiency (although at the cost of more coils).
Coil array is optimal is any environment where you want:
Perimeter coil is optimal in situations where:
There are a lot of exciting things happening of late at PowerbyProxi and in the broader wireless power industry – all in all it has kept me very busy and is partly the reason my last blog post was 3 months ago! (my travel manager tells me I have flown over 160,000 kms to meet with our many customers and partners).
Two weeks ago, to cope with exponential growth, our Auckland office (where all our clever R&D is done) moved across Victoria Park into our big new home at 43 College Hill, Freemans Bay Bay in Auckland. The dreaded move went seamlessly thanks to our wonderful Executive Assistant.
A few days prior to that move, we also welcomed Qualcomm to the Wireless Power Consortium (WPC) at their Qingdao, China meeting. At that meeting Tony Francesca (our VP of Business Development, Consumer Technologies) was also appointed to Chair the WPC’s Resonance Task Force (part of the Low Power Working Group).
The most exciting thing however is that last week we announced our strategic partnership with Samsung – after a courtship that lasted a couple of years. When we founded the company in 2007, we knew that Consumer Electronics was going to be a key market for us, but it was still too early for the technology back then. This partnership is further evidence that wireless power is fast becoming mainstream in Consumer Electronics.
For me personally, this marks the commercial realization of work that started many years ago when I was a student at The University of Auckland. We are now well positioned to leverage our wireless power technology (find out more info on wireless power) in both the consumer and industrial market segments with Samsung and TE Connectivity as strategic partners respectively.
It is certainly a very exciting time for us at PowerbyProxi. The partnership with Samsung in particular is significant for us given they have also been one of the earliest proponents of wireless power. Many Galaxy and Note smartphones have had wireless charging ports as standard for some time now, as an example.
In announcing the deal, Vice President, Hugh Kim, Director of Wireless Charging Development said “Our research identified PowerbyProxi as a leader in wireless power technology based on its expertise, track record and comprehensive patent portfolio.”
The partnership will enable us to leverage our wireless power technology and IP to deliver the best user experience to a mass audience. We are certainly excited to be working with Samsung.
With so much of what we do under wraps, it’s nice to be able to share some of the exciting things going on at PowerbyProxi. We have more major announcements coming out soon so keep your eyes peeled!
Last week I travelled to Taipei for Computex 2013 to demonstrate our latest Qi compatible wireless charging technology. What we presented was a wireless receiver that can be charged on multiple Qi transmitters, including our next generation wireless charging pad enabling multi-device charging and full spatial freedom with full Qi interoperability.
You can see the demo itself in this video which highlights our intention for it to become integrated directly into smartphones – as we have demonstrated in our Proxi Integrated Smartphone Solution previously.
However, what the demo and the underlying technology essentially shows is not only a pathway towards a better, more advanced Qi standard – but more importantly, the first step towards what everybody ultimately wants from wireless charging – interoperability.
It is something our customers have requested from us and we have set on the path to deliver – while maintaining the advantages that our Dynamic Harmonization Control technology provides.
Interoperability means that consumers have the ability and confidence to use multiple smartphones on any (Qi) compatible charging pad with the knowledge that it will not only charge, but do so efficiently and reliably. Unlike wired chargers, wireless by nature provides the opportunity to break free from model-specific charging connectors – people want to buy one pad which will charge all their phones, anywhere, without discrimination.
PowerbyProxi made a conscious choice to join the WPC in May to push the advancement of what we considered to be the leading wireless charging standard in the market (Qi) so that consumers can experience fully functional, flexible, convenient, and ultimately superior wireless charging sooner. We have only been a member for a few weeks but have already started demonstrating results that show how our multi-device and spatially free charging systems are interoperable with Qi.
You can be sure that as a member of the WPC we will continue to work with it’s members extend the specifications and the functionality of the current Qi standard while ensuring greater compatibility within the Qi ecosystem. Ultimately keeping the consumer our number 1 priority.
It was interesting to see these comments from Qualcomm in this recent Computerworld article by Lucas Mearian: Samsung uses Qi charging for Galaxy S4, but sees A4WP as the future.
“The frequencies at which tightly coupled solutions operate are not that far from the frequencies that are used for conductive cooking,” he said. “The tightly coupled solutions today have a problem where they can heat the metal surfaces in the smartphone & or metal objects. The result is that a lot of times [with] the tightly coupled solutions, the foreign object detection either dials back the power or simply turns the power off”
Let’s get a few things clear first of all:
You can have tightly coupled systems operating at high frequencies and loosely coupled systems operating at low frequencies.
And the good news here at PowerbyProxi is that in none of these cases do we design wireless charging systems like you would design induction cookers! With an induction cooker inefficiency is the target, the less efficient the better – it’s how you create heat. The opposite is true for any respectable wireless power supply. High efficiency is the target.
PowerbyProxi continues to demonstrate real wireless power solutions that prove loosely coupled systems operating at low frequencies, when designed properly, actually have better thermal performance to tightly coupled systems (when measured on all key areas of the phone like the LCD, back cover and battery as well as the transmitter surface area). This is because loosely coupled systems operating a low frequencies have superior average efficiency. Average efficiency is what the user experiences day to day (peak efficiency is what only test engineers experience). Please see Kunal’s blog on average efficiency if you don’t know what I am talking about.
Let’s remember that the user does not care about how you achieve loosely coupled or what the frequency is. The user wants to place his or her phone and other electronics devices anywhere on the pad without any thought and have it recharge as fast as a wired charger. Furthermore they want to know that is is safe to use, will not cause interference with other devices and is environmentally friendly.
The average efficiency of PowerbyProxi’s Proxi Smartphone pad (loosely coupled and operating at low frequencies) is almost triple that of a loosely coupled system operating at high frequencies. I know which one our customers call the induction cooker.
If you would like more information please contact us directly at email@example.com.
Well put Jacek Debowski! (Technical Insights Research Analyst for Frost & Sullivan).
Finally someone gets what it will take for wireless power to go mainstream in consumer applications. In an extract from the latest Frost & Sullivan report Debowski notes: “Companies have already started offering wireless charging systems with consumer electronics. However, it can become a standard feature in smartphones or laptops only when it offers higher efficiency and power, electromagnetic interference compliance and flexibility in the positioning of the charged device.” See the original article here.
We have been saying this since we were founded in 2007. Lets discuss Jacek’s points one by one.
At PowerbyProxi we have focused on providing:
In my opinion there are a few things missing from Jacek Debowski’s comment quoted above, but I was impressed to see electromagnetic interference compliance on his list. So few comment on this important topic which puzzles me, especially when so few flexible positioning technology platforms can actually meet it!
What did I think was missing? The other key things that are critical for widespread adoption of wireless power in consumer electronics are:
Some say we are the only ‘real’ wireless power company as a result 😉
Over the last few years Wireless Power has made rapid advances towards becoming a mainstream technology and is often the case, marketing departments become the source of many new inventions. Perhaps the biggest marketing “invention” to date is something called “Magnetic Resonance” (related to Resonant Inductive Coupling) when everyone else is just doing stone age “Inductive Power.”
It’s a term many have now adopted, as if it was some space-age technological leap from “Inductive Power.” When in fact Magnetic Resonance and Inductive Power are EXACTLY the same thing.
Lets dig into this a little more …
I’m sure all EEE majors will remember that Inductive Power uses Magnetic Resonance.
Any Inductive Power system has to have resonance, even the WPC which requires complete alignment between the transmitter and receiver coils uses resonance. Yes, tightly coupled systems, like loosely coupled systems, do use resonance! This is accepted science since The University of Auckland started researching modern day wireless power 20 years ago.
Originally, before induction, wireless power could be achieved by effectively taking a transformer and separating the primary and secondary coils (i.e. a split transformer).
To increase the power efficiency it was worked out a long time ago that we need to use resonant coupling. This is just a fancy way of saying that by adding capacitors on both coils, a resonant circuit is created between the inductance of coil and capacitor. At the resonance frequency, the reactance cancels out and you are left with only the parasitic effects of finite winding resistance, AC resistance (proximity effect) and dielectric losses.
If you had a perfect AC source and drive the resonant circuit you have no losses. Losses are solely limited by your parasitics.
“Magnetic Resonance” is just sticking some capacitors in place. It was great to see Marin Soljacic, the inventor of WiTricity confirm this in the IEEE publication, A Critical Look at Wireless Power. “Resonance enables efficient energy transfer…. …. it’s not a new idea: Tesla’s eponymous coils use that very same principle.”
To summarize in non-technical speak, all Inductive Power systems use magnetic resonance and its certainly not the difference between tightly coupled and loosely coupled systems.
Like most new technologies you need to get underneath the marketing spin to understand the features and benefits that each vendor can deliver to those who matter most – our customers!