Although most people are not unfamiliar with wireless charging technology, after the release of Nokia Lumia 920, the wireless charging function has received widespread attention. As one of the main selling points, wireless charging makes Lumia 920 different from the current mainstream mobile phone products, with distinctive personality. In fact, Nokia was not the first manufacturer to use wireless charging technology on mobile phones. Philips launched a mobile phone with Qi wireless charging standard a year ago, but it did not attract consumers' attention in the end.

In fact, the current wireless charging technology is not mature, not only the technology development is slow, but also the standards have not been unified. At present, there are three mainstream wireless charging standards: Power Matters Alliance (PMA) standard, Qi standard, Alliance for Wireless Power (A4WP) standard. Let's briefly introduce these three standards.

Power Matters Alliance standard

The Power Matters Alliance standard was initiated by Duracell Powermat, which is a joint venture between P&G and Powermat, a wireless charging technology company, and has excellent comprehensive strength. In addition, Powermat is one of the supporting members of Alliance for Wireless Power (A4WP) standard.

At present, AT&T, Google and Starbucks have joined the PMA Alliance. PMA Alliance is committed to creating wireless power supply standards for mobile phones and electronic devices that meet IEEE Institute standards, and has a leading position in the field of wireless charging.

At present, Duracell Powermat has launched a WiCC charging card that adopts the Power Matters Alliance standard. WiCC is one circle larger than SD card, and components such as coils and electrodes for electromagnetic induction non-contact charging are embedded inside. The card is thin and can be used by inserting it next to the existing smart phone battery. Many portable terminals can easily support non-contact charging with this card.

 
WiCC charging card

In addition, as support, Starbucks plans to conduct Duracell Powermat wireless charging pilot in 17 stores in Boston, which will provide strong support for PMA's foothold in the United States. Adam Brotman, chief digital officer of Starbucks, said: "Starbucks will install wireless charging devices on some desktops to see how customers react." If customers do not have a charging case matching the iPhone or Galaxy, Starbucks will give a small number of free gifts during the pilot period, and some of the cases will be lent at the counter.

Qi standard

Qi is the "wireless charging" standard launched by the Wireless Power Consortium (WPC), the world's first standardization organization promoting wireless charging technology. It has two major features: convenience and versatility. First of all, products of different brands can be charged with Qi wireless charger as long as they have a Qi logo. Secondly, it has overcome the technical bottleneck of "universality" of wireless charging. In the near future, mobile phones, cameras, computers and other products can be charged with Qi wireless chargers, making it possible for large-scale applications of wireless charging.

At present, the mainstream wireless charging technology in the market mainly adopts three ways, namely, electromagnetic induction, radio waves, and resonance, while Qi adopts the most mainstream electromagnetic induction technology at present. In terms of technology application, Chinese companies have stood at the forefront of the wireless charging industry. It is reported that at present, Qi's application products in China are mainly mobile phones, which is the first stage and will be developed and applied to different categories or higher power digital products in the future. So far, the number of alliance members has increased to 74, including well-known enterprises such as Philips, HTC, Nokia, Samsung, Sony Ericsson, Best Buy, etc.

Texas Instruments launched a small Qi wireless power chip

Typical representative products of Qi standard include: Nokia Lumia 920, Nokia Lumia 820, Google Nexus 4, etc. When using these mobile phones, you do not need to install any accessories. You can start charging by directly placing them on any charger that supports the Qi standard. At present, there are a large number of different types of wireless chargers available from brands such as Energizer and PowerMate.

A4WP standard

A4WP is the abbreviation of Alliance for Wireless Power standard, which is created by the wireless charging alliance jointly created by Qualcomm, Samsung and Powermat. The alliance also includes EverWin Industries, Gill Industries, Peiker Academic, SK Telecom and other members, with the goal of establishing technical standards and industry dialogue mechanisms for wireless charging devices of electronic products, including portable electronic products and electric vehicles.

The wireless charging alliance will focus on introducing the "electromagnetic resonance wireless charging" technology, which is different from Qi's "electromagnetic induction technology". These two technologies have their own advantages. The former may have lower transmission efficiency, but can realize wireless charging over a longer distance. The latter requires close contact, such as placing the mobile phone on a base, and induction charging can be carried out without wiring, but the charging efficiency is high.

The A4WP standard alliance hopes to make wireless charging rapidly popular, so that users can charge wirelessly anywhere. In other words, A4WP wants to make wireless charging cheaper and add charging interfaces without increasing the size of mobile phones, tablets or laptops, which means that more and more manufacturers will choose wireless chargers by default.

Industry insiders believe that the wireless charging alliance created by Qualcomm, Samsung, Powermat and other companies has expanded the range of targeted products, including electric vehicles and other broader electronic products.

Due to the late formation of the alliance, there are few products adopting this standard at present. Samsung has previously said that a wireless charger is included in the Galaxy S III smartphone accessories, but the launch time has not yet been determined. It is speculated that this wireless charger will meet the A4WP standard. However, due to the different technical principles between A4WP and Qi, the charger of Galaxy S III and Lumia 920 will not be universal, and users will have to prepare two chargers to charge the product separately.