Wireless charging has seen some major advances over the past decade, and this trend has continued faithfully into this year.
Basic overview of wireless energy transfer. Image used courtesy of Texas Instruments
In the past few months, researchers have found ways to maximize power transfer in a multiple-transmitter wireless charging system. Additionally, developers have pushed the bounds of proximity in wireless charging, with a company in New Zealand assessing long-range coverage and an aerospace startup sending a wireless charging system to the moon.
In this article, we’ll take a look at each of these developments to get a feel for how the field is moving.
Astrobotic: Wireless Charging on the Moon
In November, Pittsburgh-based company Astrobotic won NASA’s Tipping Point Contract worth $5.7 million to lead an effort to develop a wireless charging system for lunar applications.
Astrobotic’s chargers work on magnetic resonance (MR)-based wireless power transfer, giving them better versatility and range than a standard induction-based wireless charger. A major advantage of magnetic resonance-based wireless charging is the flexibility of motion and position.
In contrast to induction-based wireless charging, where the receiver needs to be directly on top of the transmitter, MR techniques sidestep the requirement to perfectly align the receiver and coil.
Astrobotic’s 2U CubeRover will be the first with space-qualified wireless charging. Image used courtesy of Astrobotic
Wireless charging and this technique, in particular, proves to be useful on the moon since moon dust tends to contaminate wired electrical connections and prevent them from working. Using MR-based techniques, any debris between the transmitter and receiver will not affect power transfer.
Breakthroughs in Multiple Transmitter Schemes
In a study published in IEEE Transactions on Power Electronics, researchers from Incheon National University in Korea explain a novel scheme to maximize power transfer in a multiple-transmitter wireless charging system.
The conventional approach to a multiple-transmitter system is to use a position sensor to locate the receiver and then turn on the transmitter closest to it. This is inefficient because only one of the multiple transmitters is used at a time and the transmitter may not even be aligned for maximum transfer efficiency.
a) Schematic diagram of multiple transmitter coupling. b) RX position vs. mutual inductance. Image used courtesy of Kim et al.
Instead, these researchers have developed a way to determine the coupling degree of each transmitter, so the receiver can be measured in real-time based on the perceived impedance. The researchers can then dynamically adjust the output of each transmitter coil and efficiently transfer power.
Long-Range Wireless Charging in New Zealand
In New Zealand, Powerco, one of the country’s largest power distributors, is investing in Emrod, a company working toward long-range wireless charging on a grid level.
The technology works by using a transmitting antenna, a series of relays, and a receiving rectenna, which is a rectifying antenna capable of converting microwave energy into electricity. The system uses non-ionizing industrial, scientific, and medical bands of the RF spectrum.
An Emrod wireless charging transmitter. Image used courtesy of Emrod and the New Atlas
Emrod claims that using its technology, a one-square-meter transmitter could send about 10 kW for about 10 meters, while a 40-square-meter transmitter could provide about a 30-km range. Obviously, wireless transfer will have lower efficiencies than conventional grid distribution.
Emrod understands this, instead claiming that it’s not trying to replace the current infrastructure, but simply augment it where it makes more sense.
A Wireless Future?
The field of wireless charging is hot right now, and for good reason. While there are concerns about efficiency and practicality compared to wired charging, many researchers and companies are hard at work to mitigate these issues.
Just as Nikola Tesla dreamed, a wireless future could provide us with unprecedented versatility and connectivity. With continual advances, this future doesn’t seem so distant anymore.
Other Wireless Charging Topics to Explore
Check out some of the other ways companies and researchers are tackling the challenges of wireless power transfer: