A wireless charger enables charging of electronic device such as a smartphone without physically plugging it to the adapter. The technology employs inductive coupling to transfer the energy from the charging system to the device.
The Need for a Convenient Charging Solution
The wireless chargers eliminate the need for separate adapters and cables. They provide a cable free environment with no tangled and incompatible power cords. Some of the benefits associated with the wireless chargers include;
- No maintenance of connectors
- Ability to charge mission critical systems
- Savings on cables and power
- Easily integrated to social places such as hotels and other public venues.
How the Wireless Chargers work
Alternating current is fed into the transmitter coil of the wireless charger so as to create a localized electromagnetic field. When a device with a matching coil is placed within this field, a current is developed in its receiver coil. This is then rectified and used to charge the battery in the device.
The two coils do not come into direct contact since the magnetic field has the ability to pass through glass or plastic over a distance of between 5 and 40 mm.
Figure 1: Basic operation of a wireless charger Image: computerworld
Qi wireless charging standard
Qi wireless standard was developed by the Wireless Power Consortium (WPC) comprising of over 200 technology firms. The standard outlines the transfer of electrical power within a range of 4 cm implemented using a transmission pad and a compatible receiver.
However, the power that can be transmitted from the wireless chargers is limited to below 5 volts for low power, up to 120W for medium power, and 1kW for high power.
Mainstream adoption of wireless chargers
Qi is the most popular wireless charging standard that has been adopted in a wide range of applications and products. The over 200 WPC members continue to support and drive the accelerated adoption of the technology around the world. Currently, over one million Qi wireless charging locations spreading across more than 30 countries have been installed.
Over 65 Qi compatible phones
Due to the popularity of the Qi standard, most phone manufacturers have adopted the system and over 65 Qi-compatible cell phone models have been produced. Notable makes include the Samsung Galaxy S6, Galaxy Note 5, Nexus 6, LG G4, HTC Samsung Galaxy S4, etc.
A back cover with an embedded receiver coil is usually used to add the wireless charging capability to older phones.
Qi is installed in public venues, airports, office buildings, hotels, cars
As wireless charging continues to gain momentum, and there are several Qi Hotspots spread across public venues, restaurants, airports, train stations, cars, office buildings, homes and other public places.
Typical installations include
- Tulsa International Airport where half of the airport has wireless chargers.
- Swedish furniture retailer IKEA is producing lamp stands and tables with wireless charging capabilities. The furniture comes with about six wireless charging adapter cases for phones without the wireless charger capability.
- Nine McDonald’s restaurants in Germany recently added the Qi wireless chargers on customer tables.
80% of car manufacturers will support wireless charging
Besides indoor and public venues, the wireless charging has found its way into vehicles. As a result, most of the new car models from Toyota, BMW, Volkswagen, Porsche, Audi, and Chevrolet are now integrating the wireless charging pads onto the dashboards.
Future of Wireless power
According to Navigant Research, more than 100 million handsets will have the capability of using wireless chargers by end of 2015 and this will continue to grow as the technology becomes more attractive. Additionally, the report say that the global wireless charging revenues will grow from about $1.3 billion to 17.9 Billion in 2024.