If you ever wondered how a wireless charger works or why it’s not exactly wireless, keep reading. Whether you use a Qi charging pad or hearing aids, we will explain the companies and technologies behind the power in your wireless device.
The big names in wireless charging
There are currently several companies with wireless chargers on the market. The two biggest ones are Qi standard and AirFuel Alliance.
Qi standard, pronounced CHEE, was developed by the Wireless Power Consortium. With more than 3,700 certified Qi products, it offers the most widely used wireless charging devices. Qi chargers power smartphones, wearables, and other electronic devices.
AirFuel Alliance was formed by the Alliance for Wireless Power (A4WP) and the Power Matters Alliance (PMA). Their certified devices power low-energy medical implants and electronic devices like the Samsung TV remote.
The current technology used in wireless charging
The technologies currently used are inductive, resonant, and radio frequency (RF). While Qi uses inductive charging, AirFuel Alliance uses a combination of all three.
Inductive charging occurs when energy is transferred from a transmitting device to a receiving device through aligned copper coils. When a device is placed on the wireless charger, the coil transfers its energy to the receiving device’s coil, powering the device and charging its battery. This method is generally limited in range to a few millimeters.
Resonant charging also uses coils, but transfers energy by forming an electro-magnetic field with high-frequency current. A coil with the same resonant frequency can then receive the power and convert it into an electrical current to charge the device. This method allows for some flexibility in device placement but is limited in range which depends on the rough size of the transmitting coil.
Radio frequency (RF) does not use any coils. Instead, it uses an RF transmitter that emits energy from its antenna. The energy is then harvested by a receiver device which converts it to power. This method works in powering low-energy devices from a distance.
Limitations of current wireless charging methods
Some of the biggest issues with current wireless charging methods include energy inefficiency, range limitations, and component dimension constraints.
Energy inefficiency is an important issue concerning all current methods. With inductive and resonant charging, heat-safe mechanisms prevent coils from reaching high temperatures, leading to slower charging rates. Furthermore, there is a loss of energy involved in the transfer process. RF may not have a heat-safe issue, but it experiences losses in energy, which limits its power delivery capabilities.
Range limitations are also a significant problem found in all current wireless technologies. With inductive charging, the coils must be exactly aligned, forcing the device to lay perfectly in place on its “wireless” charging base. Resonant charging may be more flexible with its alignment but holds similar limitations to its base. RF may allow for a distance up to several meters but only for low energy devices like wearables and medical devices, which may require further distances.
Component dimension constraints are due to the size limits of most devices. For an inductive or resonant wireless transmitter to send energy from a distance, the coils would need to be larger - too large for most consumer applications. RF would similarly need larger transmitting and receiving devices containing many more antennas for higher frequencies and longer ranges - an impractical idea for most smartphones and wearables.
The future of wireless charging
The race for efficient and long-distance wireless charging is in full swing. In the meantime, Qi standard’s inductive technology will continue to be installed in many new devices, as people prefer its wireless chargers even with their limitations.
There were some recent breakthroughs with Ossia's RF and Wi-Tricity's electro-magnetic resonance technologies that allow them to be used to power devices at greater distances or in higher frequencies. However, neither of them can power energy-intensive devices, such as smartphones, from a significant distance. Xiaomi announced the release of its own technology that can supposedly charge multiple smartphones from a few meters distance, but it has yet to make it to market.
Wi-Charge, the infrared power company, has shown substantial progress in this regard, most recently at the CES 2022 event. Primarily a technology licensing company, Wi-Charge has already teamed up with multiple consumer and commercial brands to power devices from a distance of 30ft. They also recently launched a few turnkey products, like the Wi-Spot digital display that is proving to be a big hit with retailers across the world. It will be exciting to see its technology incorporated in more consumer products, and maybe even smartphones.