Batteries and charging capacity are 2 of the biggest limiters of consumer technology today
While the computing, display, audio and connectivity capabilities of mobile devices have accelerated at a rapid pace, there is no Moore’s Law for battery power, with incremental increases in power capacity of lithium-ion batteries of around 6% each year.
There are often reports of new battery technologies that have the potential to totally change the battery landscape, but these have yet to make it out of university laboratories.
This dearth of progress in battery technology has spurred power-saving innovation in other areas of computing; processors are more energy-efficient, a variety of intelligent processes cull power-hungry areas of a computer’s programming and so on. However, it has not reduced the need for charging capabilities, as battery capacity progress itself continues to only be incremental.
Another area of development encouraged by the lack of long-lasting batteries has been wireless charging. The concept and basic technology behind wireless charging has been around in embryonic form for many years, since Nikola Tesla developed and patented the Tesla Coil resonant transformer technology in 1891.
Wireless Charging Methods
Mobile device wireless charging is predominantly achieved via 2 methods of radio-wave transmission. The basic principle of both methods is the same; power is generated by an AC (alternating current) flow in a transmitter coil, which intersects with the magnetic fields in a receiver coil, which induces a current in a receiver coil. Both methods can also regulate charging through ping-based data transfer to activate and deactivate the transmitter coil and conserve energy. The key difference is the frequencies at which the different coils operate.
- Inductive charging – charge is created by intersecting the magnetic fields of 2 copper coils and then passing an AC charge through the transmitter coil, which agitates the magnetic field within the receiver coil, inducing an AC charge, which is then converted into DC (direct current) before being transferred to the battery. Of the currently prevalent wireless charging specifications, both Qi and the PMA use an inductive charging method.
- Resonance Charging – resonance charging is similar to inductive charging, apart from the frequencies used. The AC charge induced in the trasmitter coil is tuned to a specific frequency that has material resonance with the receiver coil, meaning that both transmitter and receiver must resonate at the same frequency. However, the material resonance increases the efficiency of energy transfer, allowing a looser coupling and greater distance between the transmitter and receiver coils. This also allows a single transmitter coil to power several receiver coils. The Rezence technology standard developed by the A4WP uses resonance charging, while version 1.2 of Qi incorporates resonance charging into the standard.
In May 2015, the A4WP and PMA formally merged, forming a new as-yet-unnamed organisation. However, the WPC still holds a larger number of members, so the overall winner in this standards war is still uncertain.
The Future of Wireless Charging Technologies
Wireless charging to date has been limited primarily to inductive methods, with few other technologies coming onto the market. This has limited their appeal due to a lack of positional flexibility, which will be a key benefit for resonant charging technology in the coming years.
However, it will not be the case in future that induction or resonance will make the other obsolete; each has its own area where it is more useful. For example, one key benefit of resonant technology, multi-device charging over a greater distance, is not always necessary. Where a one-to-one ratio between transmitter and receiver is preferable, and lower levels of electromagnetic radiation are required, induction will persist.
However, for most CE applications, resonance allows a flexibility that induction does not, meaning that ultimately resonance will be the most popular technology for consumers’ wireless charging needs.
Over 270 million households worldwide will be using wireless charging technology by 2020. Nearly 40% of households in the US and over 20% in Europe will use wireless charging by 2020.
Source : Reproduced from Jupiter Research