Electronics has revolutionized our society by providing many devices e.g. laptops, palm pilots, digital cameras, household robots, etc. Every electronic system or device needs electric power to operate, whether it is from walled AC supply or a battery. This electric power cannot be stored infinitely in any rechargeable device like batteries, condensers or Supercapacitors. So any portable devices like laptops or mobile phones are needed to be connected to AC power lines to recharge their batteries regularly. Wireless powering of these and similar devices is now set to complete our transition to cable free wireless life.
Wireless power transfer (WPT) or wireless energy transmission is the transmission of electrical energy from a power source to a consuming device, without the use of discrete man-made conductors. WPT use wireless transmitter that uses any of time-varying electric, magnetic, or electromagnetic fields to convey energy to one or wore receivers, where it is converted back to an electrical current and then used. Wireless transmission of power has numerous advantages. For example, it makes fault-prone plug contacts redundant. Devices can be built into housings that are protected against moisture ingress. Users also don’t have to go to the trouble of plugging in cables. The conventional power transmission using transmission lines to carry power from one place to another is costlier in terms of cable costs with a huge transmission loss.
Currently, wireless power transmission is mostly used in the Consumer Electronics segment, which includes electric toothbrushes, smart phones, laptops, tablets, and wireless powering of radiofrequency identification (RFID) tags. Wireless charging is fast becoming standard on smartphones. Smartphones is the largest receiver application for wireless power transmission technology owing to the adoption of inductive wireless power transmission in various smartphones in the past years. Samsung Galaxy Series, Motorola Droid phones, and Google Nexus phones are some notable smartphones, which have wireless charging capabilities. Samsung Electronics Co., Ltd. (South Korea) has a major product portfolio of smartphones integrated with wireless charging receiver capabilities.
Samsung unveiled its new smartphones called S10 and S10plus, in March 2019. A major feature of both these smartphones is reverse wireless charging. Samsung has named the feature Wireless PowerShare. It allows a person to use the back of the phone to Qi charge another phone. The reverse wireless charging was previously placed on the Huawei Mate 20 Pro phone. However, this model was available only in a few territories, excluding the U.S.A. This aided in the sales of Samsung S10 and S10pro worldwide. Dell’s new Latitude 7285 laptop, is the world’s first laptop that can charge wirelessly, according to company. To work, you’d need the Latitude 7825’s wireless charging keyboard, as well as the wireless charging mat, which are both sold separately in a combo for $550 on top of the Latitude 7825’s base $1,200 price tag.
Notably, wireless power transmission technology is being increasingly implemented in the Healthcare, Defense, and Industrial Applications segments. It is also being used to develop electric vehicles and to enable wireless charging. The rapid adoption of Electric Vehicles (EVs) globally due to low fuel consumption and performance benefits is driving the wireless charging market demand. Technical standards are maturing and consolidating, ensuring compatibility among all transmitters, portable devices, and chargers.
Researchers are developing new methods for wirelessly transmitting power throughout a room enables users to charge electronic devices as seamlessly as they now connect to WiFi hotspots, eliminating the need for electrical cords or charging cradles. Moreover, Industry 4.0 trend and the automation of production, packaging, and assembly systems in industrial settings are driving the deployment of wireless charging. The technology reduces the risk of explosions caused by stray sparks, that occur during the disconnection and connection of power cables.The future IOT sensors, actuators and devices could benefit from such technologies.
Panasonic Corp exhibited a flexible lithium-ion (Li-ion) rechargeable battery that can be attached to human body and clothes and embedded in cards at Ceatec Japan 2017, which took place from Oct 3 to 6, 2017. The flexible battery was first announced in September 2016. But, this time, Panasonic reduced its thickness by 0.1mm and demonstrated wireless charging of the battery.
Wireless power transfer (WPT)
Wireless power techniques fall into two categories, non-radiative and radiative. In non-radiative techniques, power is typically transferred by magnetic fields using inductive coupling between coils of wire. The inductive coupling method is the most essential methods that help the experts to transfer energy wirelessly via inductive coupling. Basically, it is used for near field power transmission. However, the power transmission takes place between the two conductive materials through mutual inductance. For instance, it includes a transformer.
In radiative far-field techniques, also called power beaming, power is transferred by beams of electromagnetic radiation, like microwaves or laser beams. Microwave Power Transmission consists of two sections. It includes the transmitting section and receiving section. In the transmission section, the microwave power source generates microwave power controlled by the electronic control circuits. The waveguide circulator protects the microwave sourced from the reflecting power which connects through the co-ax waveguide adaptor.
Laser Power Transmission: Laser technology used to transfer power in the form of light energy, and the power converts to electric energy at the end of the receiver. In addition, it receives power using different sources like sun, electricity generator or high-intensity-focused light. However, the size and shape of the beam decide by a set of optics. The transmitted LASER light receives by the photo-voltaic cells. It converts the light into electrical signals. Usually, it uses optical-fiber cables for transmission.
The largest application of the WPT is the production of power by placing satellites with giant solar arrays in Geosynchronous Earth Orbit. However, it transmits the power as microwaves to the earth known as Solar Power Satellites (SPS).
Wireless power, however, has not been as successful as the technology currently faces some limitations. The transmission range of wireless power transmission through electromagnetic induction and or by magnetic resonance technique is limited. This limitation of the range poses a serious challenge for the manufacturers. The efficiency of the power is inversely proportional to the distance between the transmitter and receiver, however it is predicted to improve over time. Safety issue is also the main concern for the wireless transmission market as strong electromagnetic fields may harm the biological environment.
In recent years, near-field, short range schemes have gained traction for certain range-limited applications, like powering implanted medical devices and recharging cars, mobile and handheld computing devices such as cellphones, digital music players and portable computers from power delivery mats. More recently researchers have demonstrated the feasibility of powering sensors and devices in the far field using RF signals from TV and cellular base stations. This is exciting, because in addition to enabling power delivery at farther distances, RF signals can simultaneously charge multiple sensors and devices due to their broadcast nature.
To reach its maximum potential and meet the demands of tomorrow’s wireless war fighter, next-generation components, systems, and devices must also be designed and developed with WPT in mind to optimize form, fit, and function and also to ensure that the systems are efficient, safe, and accurate.
Rezence technology has improved the wireless charging capabilities to 1-50W range (operating at frequencies of 6.78 MHz) that has expanded the range of products beyond smart phones to include laptops, tablets, and other consumer electronics while also supporting multi-device charging.
New Zealand Is About to Test Long-Range Wireless Power Transmission
New Zealand startup Emrod is building a system to wirelessly beam power over long distances. In August 2020, Emrod received funding from Powerco, New Zealand’s second biggest utility, to conduct a test of its system at a grid-connected commercial power station. The company hopes to bring energy to communities far from the grid or transmit power from remote renewable sources, like offshore wind farms.
The system consists of four components: A power source, a transmitting antenna, several (or more) transmitting relays, and a rectenna. First, the transmitting antenna transforms electricity into microwave energy—an electromagnetic wave just like Marconi’s radio waves, only a bit more energetic—and focuses it into a cylindrical beam. The microwave beam is sent through a series of relays until it hits the rectenna, which converts it back into electricity.
With safety in mind, Emrod is using energy in the industrial, scientific, and medical (ISM) band, and keeping the power density low. “It’s not just how much power you deliver, it’s how much power you deliver per square meter,” Emrod founder, Greg Kushnir, told New Atlas. “The levels of density we’re using are relatively low. At the moment, it’s about the equivalent of standing outside at noon in the sun, about 1 kW per square meter.” But if it works as intended, the beam won’t ever contact anything but empty air. The system uses a net of lasers surrounding the beam to detect obstructions, like a bird or person, and it automatically shuts off transmission until the obstruction has moved on.
The technology—power transmission via microwave energy—has been around for decades. But to make it commercially viable, you have to minimize energy losses. Kushnir said metamaterials developed in recent years are the difference-maker. The company uses metamaterials to more efficiently convert the microwave beam back into electricity. The relays, which are like “lenses” extending the beam beyond line-of-sight by refocusing it, are nearly lossless. According to Kushnir, most of losses happen at the other end, where electricity is converted into microwave energy. Overall, he said the system’s efficiency is around 70%, which is short of copper wires but economically viable in some areas. And it’s those areas the company’s aiming for. “…we don’t foresee in the near future a situation where we could say all copper wire can be replaced by wireless,” Kushnir said. “Inherently, it’ll have lower efficiency levels. It’s not about replacing the whole infrastructure but augmenting it in places where it makes sense.”
The company’s prototype can currently send a few watts of energy over a distance of about 130 feet. For the Powerco project, they’re working on a larger version capable of beaming a few kilowatts. The plan is to deliver the new system to Powerco in October, test it in the lab for a few months, and then, if all goes to plan, try it out in the field. The tests will aim to validate how much power the system can transmit over what distance. Though the current model is modest, Kushnir says it should scale.
“We can use the exact same technology to transmit 100 times more power over much longer distances,” he said in a press release. “Wireless systems using Emrod technology can transmit any amount of power current wired solutions transmit.” Ray Simpkin, Emrod’s chief scientific officer, told IEEE Spectrum that the company is also looking into whether they could beam power across 30 kilometers of water from the New Zealand mainland to Stewart Island. He said the system could cost as little as 60 percent of an undersea cable. Ultimately, the technology may help power rural areas or transmit energy from offshore wind farms, both cases where it’s expensive to build physical infrastructure to tap or feed the grid. In other cases, say in national parks, a mode of wireless transmission could have less impact on the environment and require less maintenance. Or it might be used to provide power after natural disasters in which physical infrastructure has been damaged.
China is getting ready to introduce wireless charging of electric vehicles.
The China Electricity Council (CEC) ratified and published a set of national standards for electric vehicle wireless charging, which will be based on the magnetic resonance technology developed and patented by WiTricity, a wireless power transfer specialist based in Massachusetts.
Lack of standardization was always a major obstacle for the popularization of the wireless charging, but it seems that in the near future the industry will finally introduce a general solution for all EVs – not only in China, but also globally. “For the past four years, WiTricity has been actively involved in the Chinese EV wireless charging standardization process through its work with China Electric Power Research Institute (CEPRI), China Automotive Technology and Research Center (CATARC) and the CEC. With a global IP portfolio of over 1400 issued and pending patents, WiTricity has declared twenty Chinese patents as “standards essential” to systems implementing the GB standard.
Chinese automakers and their Tier 1 suppliers rely on the GB standard committee to define the EV wireless charging solution to be deployed in China. The ratified standard is now a major market enabler for deployment on vehicles and in public charging infrastructure. WiTricity has worked closely with the GB standard committee on several significant technical matters, including efforts to harmonize the China standard with other international standards (SAE J2954, ISO 19363, IEC 61980) that will be published in 2020 and 2021.”
Wireless power transmission in robotics (drones)
The wireless power transmission technology has been used for the research and development of mini and micro robots for wireless power transfer. Several research programs pertaining to wireless powered-drones are taking place. A transmitting coil is expected to transmit power at a higher frequency, which would be received by the receiver in robots. Imperial College of London has successfully demonstrated the wireless-powered drone which is likely to operate above five inch of wireless power transmitter. ZiiEnergy, Inc. (U.S.) developing the wireless drone receiver which works on Open Dots Alliance (ODA) standards and can deliver 45 watts of power to drones.
Power over Wi-Fi or PoWi-Fi
Power over Wi-Fi utilizes a ubiquitous part of wireless infrastructure, the Wi-Fi router, to provide far-field wireless power without significantly compromising network performance. PoWiFi combines two elements: (1) a Wi-Fi transmission strategy that delivers power on multiple Wi-Fi channels and (2) energy-harvesting hardware that can efficiently harvest from multiple Wi-Fi channels simultaneously This is attractive for three key reasons:
• In contrast to TV and cellular transmissions, Wi-Fi is ubiquitous in indoor environments and operates in the unlicensed ISM band where transmissions can be legally optimized for power delivery. Repurposing Wi-Fi networks for power delivery can ease the deployment of RFpowered devices without additional power infrastructure.
• Wi-Fi uses OFDM, an efficient waveform for power delivery because of its high peak-to-average ratio. Given Wi-Fi’s economies of scale, Wi-Fi chipsets provide a cheap platform for sending these power-optimized waveforms, enabling efficient power delivery.
• Sensors and mobile devices are increasingly equipped with 2.4 GHz antennas for communication via Wi-Fi, Bluetooth or ZigBee. We can, in principle, use the same antenna for both communication and Wi-Fi power harvesting with a negligible footprint on the device size.
The key challenge for power delivery over Wi-Fi is the fundamental mismatch between the requirements for power delivery and the Wi-Fi protocol. While the harvester can gather energy during WiFi transmissions, the energy leaks during silent periods. In this case, the Wi-Fi transmissions cannot meet the platform’s minimum voltage requirement. Unfortunately for power delivery, silent periods are inherent to a distributed medium access protocol such as Wi-Fi, in which multiple devices share the same wireless medium. Continuous transmission from the router, while optimal for power delivery, would significantly deteriorate the performance of Wi-Fi clients and other nearby Wi-Fi networks.
Vamsi Talla and pals at the University of Washington in Seattle, have developed a way to broadcast power to remote devices using an existing Wi-Fi technology, they call their new approach power over Wi-Fi or PoWi-Fi. In their experiment camera could use Wi-Fi signals to create and store power, though slowly to take no more than one photograph every half an hour using their Wi-Fi charging system. PoWiFi can power devices up to 17-28 feet away from a normal Wi-Fi router.
The UW researchers have already launched the PoWiFi system in six homes in a metropolitan area and measured the impact on the residents’ browsing experiences. Browsing speeds were hardly slowed down at all with PoWiFi in place, and users typically didn’t notice a difference. With that test, the researchers demonstrated that the system can work in real-world networking situations, and won’t create a nuisance.
Because of limitations on the router power to 1 watt in the US (100 milliwatts in the Europe), the team has been able to charge up only low-power devices such as simple rechargeable batteries, simple temperature sensor, a grayscale camera with low resolution, and the charger for a Jawbone Up24 wearable fitness tracker. Another downside is that the farther the object is away from the router, it takes longer to charge.
In future, PoWiFi could be used to charge “Internet of Things”, area that embeds computing sensors in everyday objects.
Wireless charging on the move on the vehicles
Wireless power transfer (WPT) or inductive power transfer (IPT) promises convenient, autonomous, and highly efficient charging of electric vehicles (EVs). Compared to conductive charging systems, which require heavy gauge cables with potential electrical and ergonomic hazards, wireless charging is convenient, flexible, and capable of fully automated charging, despite potential electromagnetic safety or cybersecurity risks. With power transfer levels increasing beyond 100 kW, many technical and risk management challenges emerge.
Qualcomm imagines a future in which wireless charging plates are as ubiquitous as Wi-Fi hotspots, even suggesting highway charging lanes, where electric can top up their batteries as they drive. Technology that will allow electric cars to top up their charge on the move is being readied for production in the next decade. An electrically live coil is buried under the road, and when a car equipped with another coil passes over it, it induces a current in the car’s coil. This feeds into the EV’s battery and keeps it topped up.
The ‘electric road of the future’ could be a reality sooner, but car makers will need to design the next generation of electric vehicles (EVs) to incorporate induction charging pads into their technical make-up. Road infrastructure companies, meanwhile, will need to install multiple numbers of pads under road surfaces to make the idea a reality. Although the car passes over the pad buried under the road in fractions of a second, up to 20kW of energy can be pulsed into the EV, which car be travelling at speeds of up to 60mph. That’s about the same amount of energy that an EV uses when cruising. Qualcomm’s engineers claim that enough energy can be passed to an EV to keep it moving at that speed without depleting the battery, so charge can be maintained to be used at other locations where there is no induction charging.
Ultimately, a complete road network could be equipped with induction pads, allowing EVs to travel distances unlimited by battery capacity. Research suggests that if 250 metres of every kilometre of motorway was equipped with wireless charging, an EV could travel without depleting its reserves. The trial in France will examine all the extremes of operation, including coping with wet weather, vehicles passing over the coils out of alignment by up to 50%, variations in the power supply and the durability of the hardware during extended use.
Wireless charging for electric cars
Qualcomm has already fitted its Halo system of inductive chargers to Formula E course cars and other test vehicles, now it has licensed Swiss electric car parts maker Brusa, to develop, manufacture, and supply its Halo charging plates to other companies. Japanese automaker, Toyota, has signed an agreement to licence the intellectual property of WiTricity Corp. that will allow charging of the electric vehicles by parking over small fifty centimeter square charging pad. One of the major limitations of this technology is the limited operating distance.
This wireless charging solution works by fitting vehicles with a compatible receiver. Cars can then simply be driven into position over a charging pad measuring around one meter across and just a few centimeters thick. Charging pads can be portable or fixed permanently in place, depending on requirements. Once parked over the charging pad, the driver launches the charge cycle via an accompanying mobile application. As well as monitoring the process, the app helps guide drivers into position when aligning the vehicle over the charging pad, ensuring optimal results.
Wireless charging for cars is more difficult than phones, due to the higher wattage necessary. “Wireless charging will win,” said Brusa’s CEO Josef Brusa in a press statement about the agreement. “It will give e-mobility a big boost; it will set new, sustainable technology apart from old gasoline-based technology. We are determined to make wireless charging a reality.” Although wireless charging isn’t any faster than using cables, companies hope that the convenience of park-to-charge will win customers.
ORNL surges forward with 20-kilowatt wireless charging for vehicles
The Department of Energy’s Oak Ridge National Laboratory has made a recent breakthrough with a proof-of-concept 20kW charger working at 90 percent efficiency. That’s enough to put 60 miles of charge into a Tesla every hour, right on par with Tesla’s own home chargers. “The high-frequency magnetic fields employed in power transfer across a large air gap are focused and shielded,” Chinthavali said. “This means that magnetic fringe fields decrease rapidly to levels well below limits set by international standards, including inside the vehicle, to ensure personal safety.”
The researchers are already looking ahead to their next target of 50-kilowatt wireless charging, which would match the power levels of commercially available plug-in quick chargers. Providing the same speed with the convenience of wireless charging could increase consumer acceptance of electric vehicles and is considered a key enabler for hands-free, autonomous vehicles. Higher power levels are also essential for powering larger vehicles such as trucks and buses.
UK to trialling in-road wireless charging tech for electric vehicles
Charging up electric vehicles could soon go wireless as a new multi-million pound trial gets underway in a UK city. Multiple electric cabs in Nottingham will be able to recharge at once while parked in taxi ranks without needing to connect to a stationary device. The government, which will invest £3.4m ($4.4m) in a scheme that could eventually be rolled out for broader public use, hopes the new technology will provide a viable alternative to plugs and chargepoints – enabling drivers to recharge more easily and minimising street clutter.
Highways England has announced plans to test concept of “Electric Charging Roads” that will charge electric vehicle as we drive on it. It will initially carry out test track trials initially, followed by subsequent on-road trials of the technology, which is designed to increase the range of EVs. Highways England says it is also committed to installing plug-in charging points every 20 miles (32 km) on the motorway network.
New technologies being trialled or rolled out have included smart charging, lamp post chargepoints and induction pads – but there are big hopes for the impact wireless charging could have on raising the EV sector’s share of road transport. Cables buried underneath the roadway would generate electromagnetic fields that could be picked up by a receiver in the vehicle and transformed into electric power. The system would require a communication system, so that the roads can detect if a vehicle is coming and initiate the process. UK Transport Minister Andrew Jones says the trials will help to keep Britain at the forefront of the development of this technology. As the technology allows for shorter and more frequent bursts of charging, it will particularly benefit cars with smaller batteries, where “range anxiety” is most rife among drivers.
Wireless Power transfer for Military
WPT has the unique potential to transform war fighting of the future and alleviate the battlefield battery burden for both soldiers and manned and unmanned vehicles on land, air, and undersea. QinetiQ’s Talon robots that were deployed in Afghanistan automatically recharged their batteries when they were docked to an armored vehicle.
Other recent examples are charging of Soldier’s central battery from vehicle seat back as they sit in vehicles, charging of handheld devices through vests, powering helmet-mounted devices through Soldier vest-to-helmet WPT, Soldier helmet-to-goggle WPT to power devices such as night vision, radio devices and defog optics.
In the future advancements in wireless energy transfer will enable distribution of power amongst power sources, multimodal energy harvesters, and loads to occur wirelessly on the Soldier as a platform, so that all carried equipment will be powered and ready for operation at all times without thought to replacing individual equipment power sources.
As a long term goal, the Army is looking to supply troops remotely using wireless systems that could transfer power from a drone to solar panels or other devices that soldiers could plug into on the battlefield, officials said.
Wireless power Market
The Global Wireless Power Transmission Market accounted for $5.26 billion in 2018 and is expected to reach $29.23 billion by 2027 growing at a CAGR of 21%. Consumer preference for wireless connectivity, and need for effective charging systems are likely to boost the growth of the wireless power transmission market. However, high cost of wireless power transmission technology-based devices is likely to hamper the profit boundaries.
Wireless power transmission is a process that occurs in a system, where power source transmits electromagnetic energy to electric load with no wires. This wireless transmission transmits power to remote locations. Wireless power transmission has great demand in the consumer electronics, for example laptop, tablets, smartphones and other devices. Furthermore, the technology is rapidly being implemented in sectors such as defence and healthcare.
The future of the wireless power transmission market looks promising with opportunities in the smartphone, notebook, tablet, wearable electronic, and electric vehicle charging applications. The major drivers for this market are increasing consumer preference for wireless connectivity, growth in electric vehicles, and increasing need for effective charging systems. By geography, Asia-Pacific is likely to have a huge demand due to the penetration of electronic industries and rising electronic business in the region, and rising disposable income of the population.
Some of the Key wireless power transmission companies profiled include Integrated Device Technology, Qualcomm, Samsung Electronics, TDK Corporation, Texas Instruments, Nucurrent, and Witricity Corporation.
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