Jan 5, 2018

How Wireless Charging Works

Wireless charging, inductive charging, or cordless charging, are all the same thing. It uses an electromagnetic field to transfer energy between two objects through electromagnetic induction, so it will work with any wireless charger carrying the same standards of technology. The Qi wireless charging standard from the Wireless Power Consortium has been around for over five years. The basic technology has been used for consumer products like razors and toothbrushes, plus a variety of non-consumer tools for a while.

Many smart phone companies use wireless charging for high end devices. In addition, a growing number of restaurants, airports, hotels, etc. now provide wired and wireless charging.

Electromagnetic fields are created and allow the current to pass between the charging and the surface of the charging pad. The charging base station needs to be connected to a power outlet. There is a transmitting coil in the charger circuit and power from the source is supplied to the coil. Phones and other devices have a receiver coil attached to the battery, which picks up the magnetic field.

Productive coupling between the coils requires accurate positional alignment. This can be accomplished in different ways. The charging pad or base station can have visual or tactile signifiers of the optimal position for the phone; this is cheap and easy, but it presents challenges when dealing with phones of different sizes and configurations. Alternatively, a charging station might have a coil that moves to align with the coil in the device, allowing you to place it wherever you want. Another way is using an array of coils, where specific coils are activated in proximity to the device’s placement.

The base station does not activate unless a compatible device has been placed on it. The station determines this by sending an intermittent test signal to check if a compliant device is present. The mobile device responds to this ping by communicating the received signal strength. When the device’s charge is complete, it tells the transmitter to go inactive.

One ongoing problem to widespread adoption is competing standards that fracture the market and make adoption less attractive for both consumers and manufacturers.

Wireless charging may be fun and whiz-bang, but it is slower than the traditional form of charging due to less energy transfer.

New technology may let you charge your devices from a distance of three feet or more without any pad involved. The Federal Communications Commission, during December 2017 approved technology from Energous using radio frequency energy to recharge multiple devices such as smartphones, tablets, smart watches, headphones, speakers, keyboards and fitness trackers from up to three feet away.