While charging at a distance has big potential, the public face of wireless charging has until now remained with charging pads. began shipping a wireless power transfer system based on WiTricity's technology for automatic guided vehicles (AGVs). AGVs equipped with Daihen's D-Broad wireless charging system can simply pull up to a charging area to power up and then go about their warehouse duties. The system isn't just for cars: Last year, Japan-based robotics manufacturer Daihen Corp. WiTricity also adds capacitors to the conducting loop, which boosts the amount of energy that can be captured and used to charge a battery. The use of resonance enables high levels of power to be transmitted (up to 11kW) and high efficiency (greater than 92% end-to-end), according to WiTricity CTO Morris Kesler. In WiTricity's car charging system, large copper coils – over 25 centimeters in diameter for the receivers – allow for efficient power transfer over distances up to 25 centimeters. Soljačić started WiTricity later that year to commercialize the technology, and its power-transfer efficiency has greatly increased since then.

In 2007, MIT physics professor Marin Soljačić proved he could transfer electricity at a distance of two meters at the time, the power transfer was only 40% efficient at that distance, meaning 60% of the power was lost in translation. It licenses loosely-coupled resonant technology for everything from automobiles and wind turbines to robotics. That's the tactic WiTricity, a company formed from research at MIT a decade ago, has helped pioneer. In the case of smartphone wireless charging pads, for example, the copper coils are only a few inches in diameter, severely limiting the distance over which power can travel efficiently.īut when the coils are larger, more energy can be transferred wirelessly. The bigger the coil, or the more coils there are, the greater the distance a charge can travel. Coil size also affects the distance of power transfer. This is resonant inductive charging or magnetic resonance it enables power transmission at greater distances between transmitter and receiver and increases efficiency. If the appropriate capacitance is added so that the loops resonate at the same frequency, the amount of induced current in the receivers increases. It works like this: A magnetic loop antenna (copper coil) is used to create an oscillating magnetic field, which can create a current in one or more receiver antennas.

Ikea's wireless charger line-up, which includes a pad that's capable of charging three devices at once (center). There are charging pads that use tightly-coupled electromagnetic inductive or non-radiative charging charging bowls or through-surface type chargers that use loosely-coupled or radiative electromagnetic resonant charging that can transmit a charge a few centimeters and uncoupled radio frequency (RF) wireless charging that allows a trickle charging capability at distances of many feet.īoth tightly coupled inductive and loosely-coupled resonant charging operate on the same principle of physics: a time-varying magnetic field induces a current in a closed loop of wire. How wireless charging worksīroadly speaking, there are three types of wireless charging, according to David Green, a research manager with IHS Markit. That's the type of charging Apple has incorporated into the iPhone 8 and the iPhone X.

The most popular wireless technologies now in use rely on an electromagnetic field between a two copper coils, which greatly limits the distance between a device and a charging pad. The wireless charging circuit board used for Ossia's Cota RF technology, which can send power over distances greater than 15 feet. Wireless charging is making inroads in the healthcare, automotive and manufacturing industries because it offers the promise of increased mobility and advances that could allow tiny internet of things (IoT) devices to get power many feet away from a charger.

Wireless charging flux networks