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:
- Are you aware of ICNRIP, and the guidelines established by this organization?
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;
- Have you investigated what the safety limits are for Human RF (Radio Frequency) exposure? Then as a further consideration, how do these limits impact transmission distance and maximum output power?
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….
- What are your top 3 priorities for a wireless power system?
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:
- Can the technology you are considering meet your safety, EMC and efficiency targets with your top 3 priorities?
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.
- Do you know (have they told you) how the technology achieves this balance?
..and one more (necessary) check…
- Have you seen technical details and rigor showing this is possible? or was it some neat marketing slides and a cool demo?
If it all checks out, then it shouldn’t be too much hassle for them to let you do some tests yourself, right?
- Have they let you measure their demo system for EMC and RF Exposure in an independent lab?
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.
- What is the effieicncy of the proposed system? And how are they measuring it?
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…
- Is efficiency being measured across a load range and range of X/Y/Z positions?
- Do they know the absolute best and worst-case efficiency a user will experience (both where/how and how much)?
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.