Tag Archives: wireless charging

Wireless Charging for Drones

Drones face a significant operating challenge—their limited battery capacity places a constraint on their flight time. More flexible and efficient recharging solutions can address this issue. A 4-year old startup, WiBotic, now has funding to explore this avenue. WiBotic designs and manufactures solutions to charge robot and drone batteries.

WiBotic offers power optimization and wireless charging solutions for mobile, aerial, marine, and industrial robots. Their Adaptive Matching technology is a new method for inductive power transfer. The company is providing power levels necessary for charging flying devices such as drones.

Software libraries monitor battery charge parameters in detail for providing optimization solutions. Combined with wireless charging hardware, the strategic deployment of these software features helps with the optimization of drone uptime. Wireless charging solutions from WiBotic also schedule the recharge, allowing multiple drones to charge from the same transmitter at various times.

Nikola Tesla was the first to demonstrate, in the late nineteenth century, the use of electromagnetic fields as a source of electricity transfer without wires. Although engineers are aware of the wireless methodology, the design of an entire system consisting of transmitters and receivers, their locations, and maximizing their efficiency is a complex challenge requiring specific skills. Most wireless power transfer systems use inductive coupling or magnetic resonance with their individual strengths and weaknesses.

Inductive coupling is the most common method, usually found on consumer devices. However, they are efficient only when the transmitter and the receiver antennas are close together. Therefore, this method is not suitable for drones and robots as they cannot position themselves so that their inductive systems are close enough to provide a reliable power transfer.

The technology of magnetic resonance is one of the latest providing more flexibility in positioning. Most magnetic resonance systems have a special area for delivering power with maximum efficiency. If the robot or the drone stops in this area only briefly or remains off-center, the charging efficiency reduces, and the charging time increases.

WiBotic technology incorporates the best of both systems and operates on the strengths of both resonant and inductive systems. They have a patented Adaptive Matching system to constantly monitor relative antenna positions, while dynamically adjusting both hardware and firmware parameters for maintaining maximum efficiency. This ensures delivery of high-power levels and reliable charging, even when several centimeters of angular, horizontal, or vertical offsets separate the transmitter and the receiver.

For drones, the WiBotic wireless charging station is a square platform of about 3 ft x 3 ft. It has an intelligent induction plate that determines the type of battery the drone has and establishes the proper charging parameters for it.

WiBotic wireless charging systems all have four primary hardware components—the transmitter antenna coil, the receiver antenna coil, the on-board charging unit, and the transmitter unit.

Using an AC source, the transmitting unit produces a high-frequency wireless signal, that travels to the transmitting antenna coil and generates electric and magnetic fields.

The transmitter unit has the capability to recognize an incoming drone equipped with a receiver antenna coil, which automatically activates itself to receive the right amount of energy.

Wireless Charging and Electric Vehicles

In our daily lives, we are increasingly using wireless products. At the same time, researchers are also working on newer trends in charging electric vehicles wirelessly. With more countries now implementing regulations for fuel economy and pushing initiatives for replacing fossil-fuel based vehicles with those driven by electricity, automotive manufacturers have focused their targets on development of electric vehicles. On one hand there are technological advancements on lithium-ion batteries and ultra-capacitors, while on the other, researchers are working on infrastructure and the availability of suitably fast charging systems that will lead to a smoother overall transition to the adoption of electric vehicles.

Charging the batteries of a vehicle requires charging systems using high power conversion equipment. They convert the AC or DC power available from the power supply sources into suitable DC power for charging. As of now, the peak power demand from chargers is of the order of 10-20 KW, but this is likely to climb up depending on the time available for charging, and the advancements made in capabilities for battery charging. Therefore, both governments and OEMs are gearing up for developing high-power charging systems to cater to the power needs of future electric vehicles.

Wireless charging systems transfer power from the source to the load without the need for a physical connection between the two. Commonly available schemes use an air-cored transformer—with power transfer taking place without any contact between the source and the load. Wireless power transfer technology is available in various ranges, starting from mobile power charger systems rated for 10s of watts, to high power fast chargers for electric vehicles rated for 10s of kilowatts.

Earlier, the major issues with wireless charging systems were their low efficiency and safety. The technology has now progressed to the stage where achieving efficiencies of over 80% is commonplace. Although this is on par with wired power charger systems, increasing the spacing between the primary and secondary coils allows the efficiency to drop exponentially, which means the efficiency improves as the spacing between the coils decreases. Researchers are also looking at adopting various other methods of constructing the coils to address the issue.

Likewise, smart power controls are taking care of safety, by detecting power transfers taking place spuriously and suspending power transmission directly. Manufacturers are ensuring safety at all stages by implementing regulatory guidelines such as SAE J2954.

Although several methods exist for wireless power transfer, most popular are the resonance and inductive transfer methods. The inductive method of power transfer uses the principles of the transformer, with the AC voltage applied to the primary side inducing a secondary side voltage through magnetic coupling, and thereby transferring power.

The inductive method of power transfer is highly sensitive to the coupling between the primary and secondary windings. Therefore, as the distance increases, the power loss also increases, reducing the efficiency. That restricts this method to low power applications alone.

Based on impedance matching between the primary and the secondary side, the design of a resonant method allows forming a tunnel effect for transferring magnetic flux. While minimizing the loss of power, this method allows operations at higher efficiency even when placing the coils far apart, making it suitable for transferring higher levels of power.

QSCR: Using A Wireless Hotspot To Charge Your Phone

Using the smartphone is always a pleasant experience, until the charge runs out. The only option left is to plug the phone into a charging arrangement, usually a mains-operated power supply that connects to the phone by a USB cable. The main disadvantage of this method is it limits the freedom of mobility of the phone until it is charged up again. That leaves people to wonder as to how long before smartphones could be charged wirelessly same as everyone uses Wi-Fi to link to the Internet.

Now, researchers at Disney Research have done the inevitable. They have discovered a method of charging electronic gadgets without using any type of cords or cradles. Not only can you charge a number of electronic devices through Wi-Fi anywhere in your room, you could simultaneously power fans, cellphones, and lights as well.

Quasistatic Cavity Resonance (QSCR), as the Disney researchers have named the technology, has been tested successfully during recent trials. The researchers generated near-field standing magnetic fields within a closed space. Filling a 16-ft. x 16-ft. room, these field waves were able to charge standard electronic gadgets within the room. However, the room needed to have special properties, such as metalized walls, floor, and ceiling.

Within this metal room, the scientists could generate magnetic waves suitable for charging several smartphones, glow a few lamps, and operate fans at the same time. In total, they transmitted about 1.9 KW of power, sufficient to charge about 320 smartphones simultaneously.

The trial has established that the innovative method has the capability to transfer electrical power as easily as Wi-Fi does. According to Alanson Sample, this could help power new applications for small mobile devices such as robots, as they would not need battery replacements or charging wires. Alanson is the principal research scientist and associate lab director at Disney Research.

Although the demonstration used room-scale wireless power, Alanson informs it could easily be scaled up to the size of a warehouse or down to the size of a toy chest.

Although wireless charging is not a new idea, it has always been a long-standing dream for many. In 1890s, Nicola Tesla had already demonstrated wireless lighting systems and proposed ideas of long distance power transmission without wires. However, none of that ever came into existence.

So far, transmitting power wirelessly has been accomplished only for short distances, mostly for charging stands or pads. However, the new technology, QSCR, will help to increase the transmission distance to many times over.

Once the researchers channeled electric power through the metalized walls, ceiling, floor of the room using the Quasistatic Cavity Resonance technique, there was enough uniform and strong magnetic fields inside the room. Receiving coils designed to intercept these magnetic field resonate at the same frequency because of capacitors placed across the coils. The induced currents within these coils can transfer the power at low frequencies to any device containing the receiving coils within the device. Making a room metalized is also not difficult, as it requires only a thin metallic coating on the walls.

Light up for Wireless Charging

Wi-Charge, a wireless charging company from Israel, has demonstrated a light-based charger at the Mobile World Congress. Along with other few existing wireless charging methods, the Wi-Charge method of charging provides an alternative to support background charging across longer distances compared to those offered by existing rivals. Wi-Charge develops receivers and transmitters that utilize laser light for charging a wide range of devices. The transmitters are typically shaped to fit into wall or light bulb sockets and provide a constant charge. Incidentally, these devices do not operate with infrared light as do some other makes of chargers, and therefore, do not produce unsafe radiation.

The charging system developed by Wi-Charge is called the distributed resonator. It consists of a high-power light source focused with two retro reflective mirrors, very similar to reflectors typically used on a bicycle. One of the mirrors focuses the laser transmitter and the other has a photovoltaic cell at its focal point at the receiving end. This way, Wi-Charge has a closed loop system that prevents the ultra-high energy to stray and enter the human body.

The distributed resonator charging device transmitter supports multiple devices. The total number of charging devices ultimately depends on the battery size being charged. The smart home device, which Wi-Charge will release first in the market, will come with a receiver module capable of charging up to 2W with a plug-in transmitter capable of covering a room 15-foot long.

Another model, meant for charging mobile devices, measures 17x17mm and has a transmitter capable of delivering 10W. The model has two receivers capable of charging devices at 5W each. Wi-Charge demonstrated this by charging a Samsung Galaxy S4 at the end of a 10-foot long table capable of rotating up to 80-degrees.

The basic idea behind the Wi-Charge wireless chargers is to keep devices always charged, never allowing them to drain or become empty. For this, their chargers pump in just enough power required for the device to be normally used pus a little extra.

The company has developed other form factors as well. One of their chargers is shaped like a dongle that attaches to a speaker in a phone case with an embedded receiver. Ultimately, the company plans to integrate their transmitters inside smart light bulbs.

Their plan is to integrate the receiver within the device being charged. According to their CEO, the transmitter could be embedded in the front part of the phone or even go under the glass of the screen. As the company is not competing to provide the fastest charging method, users can expect their empty devices to charge up completely within 2-3 hours.

At present, coil-based chargers dominate the wireless charging arena. That makes it a challenging proposition for Wi-Charge to enter the market. Currently, Wi-Charge is working to increase the charging distance of its transmitters to 30 feet, while reducing their size to 10x10mm.

While the consortia of inductive chargers fight each other for dominance, Wi-Charge is confident the very weak value proposition of the inductive chargers will allow their long-range power to be considered superior. Accordingly, Wi-Charge is hoping to partner with larger OEMs to drop the prices of their devices by proliferation.