Wireless charging. It doesn’t really do what it says on the tin

18-01-2018 |   |  By Paul Whytock

As far as consumers and their smart phone go, wireless charging sounds a great idea. And if it was a reality it would be. Let’s face it, relative to much of our technology-driven lives, wireless is the way to go.

But getting back to those smart phones I still think that wireless charging doesn’t offer the convenience or efficiency and, in some instances, the safety of just plugging one end of your phone charger into a socket and the other into the base of your phone.

As well as that, wireless charging capability can add costs to the design of a phone which have to be passed onto the consumer, and that is not a good thing in such a cost competitive market.

Convenience wise I really don’t see the point. You have to plug your charging pad into an electrical socket and then place you phone precisely on the charging pad. So in effect you have replaced one charging wire with another. Personally I have wall sockets at home which mean I can charge my phone with its normal wired charger and I can still use the phone because its not marooned on a charging pad.

Ok so wireless charging you phone in your car is a good thing. It actually deters you from breaking the law because it’s an inconvenient distraction to try and use the phone while it’s charging. More on an in-car charging development later.

Wireless charging happens in two ways; conductive which links conductive material in a charging pad to integral conductive material in the phone, and inductive which uses a charging station which has an induction coil in it.

Inductive charging is a complex business and not necessarily very efficient or fast. It employs two electromagnetic coils to create a magnetic field between two devices. The principal is to use the effects of a magnetic field to take electricity from, for example, a mains electrical supply which them becomes electromagnetic prior to it being converted back to electricity to feed the phone’s battery.

All this is pretty smart but hardly qualifies as truly wireless charging because the charging matt or dock has to be plugged in and is definitely not what the early pioneers had in mind when it came to the wireless transfer of electrical power.

Back in the 1860s radio waves were first considered for power transportation by James Maxwell and twenty years after that Heinrich Hertz showed evidence of radio waves using his sparkgap radio transmitter. At the same time engineer and physicist Nicola Tesla was convinced wireless power transfer was feasible. He built a giant coil connected to a high tower with a metre diameter ball on it and then proceeded to push close to 300kw of power into the thing. Unfortunately the experiment failed due to the power scattering in multi-directions. (pictured)

Coming back to the modern day and the inaccurately titled, wireless charging concept, there are plenty of electronics developments that are moving the idea forward. Only this week German chipmaker Infineon unveiled some microcontrollers families which it claims will make wireless charging easier and more efficient.

The company’s AURIX and XMC microcontroller families provide design-flexible chipsets for wireless charging apps and reference designs for both inductive and resonant wireless charging solutions for in-car, at home or in public places.

The controller supports today’s 15W charging standards, including fast-charge smart phones, and can support future changes through software updates claims Infineon.

The IXMC microcontroller has a scalable architecture that can support a fast charge smart phone. Paired with power products, like MOSFETs and Driver ICs, this system is said to be able to provide full power wireless charging without complicated thermal management issues which could perhaps take care of some of the inherent heat problems with some forms of wireless charging.

The XMC based 2.5W low-power solution supports both one-to-one and multi-device charging on a single transmitter by using small high-frequency coils which can be implemented in a variety of form factors.

So there is no doubt that some of the technical inadequacies of wireless charging are being gradually resolved but for the moment I’ll stick to the very portable, flexible and user-friendly charging system that came in the box with the phone.


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By Paul Whytock

Paul Whytock is European Editor for Electropages. He has reported extensively on the electronics industry in Europe, the United States and the Far East for over twenty years. Prior to entering journalism he worked as a design engineer with Ford Motor Company at locations in England, Germany, Holland and Belgium.

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