Wireless charging is about to take off

Electric cars, mobile devices and industrial applications are refocusing on wireless charging technology.

It is well known that electricity travels long distances through the air, but without wires, there never seems to be a practical or reliable way to power electronic devices.

In fact, wireless power has been available for years. Whether wireless power will extend battery life is not entirely clear. However, battery capacity has been slow to improve in contrast to the increasing processing power and functionality of terminal devices, and wireless charging is gaining renewed attention in order to ease the tension between growing capabilities and lagging batteries, as well as to cope with the continued growth of emerging markets such as electric vehicles and connectivity industrial applications.

"I remember, 10 or 15 years ago, medical implants could be recharged using a cuff or a coil, so you didn't have to go back to the surgery." JeffMiller, product marketing manager for Siemens - Mentor. "Or when you're charging a tire pressure monitoring system in a truck, you can't do that because you don't have wires on your tires, and you don't want to take your tires off, so you have to do it in a different way."

Most wireless charging scenarios involve industrial, automotive, or low-end consumer products such as rechargeable electric toothbrushes, but smartphones are increasingly incorporating wireless charging capabilities as well. Smart phones are mainly based on the Qi standard, which relies on the magnetic induction between the transmitter and receiver to complete the energy transmission. During charging, the transmitter and receiver need to be close to each other, almost touching each other.

In addition, people can still trying to develop within a few feet away from charge at the same time to complete mobile phone charging scheme, and the solutions in addition to charge their phone, and may at the same time by using magnetic field, ultrasonic, laser, or various frequency rf signal to many other charging device, in addition to charging, even can also transmit the media data.

"The basic physics of transmitting electricity without cables has been around for decades, and the challenge is not to transmit electricity through air, but to be able to transmit electricity without interference, within a limited field strength, and at the same time bring down the cost and make it a mass-market product." MennoTreffers, President of the wireless charging alliance (WPC). The alliance's goal is to merge the previous two competing specifications into its Qi standard for near-field phone charging.

Treffers said it would be difficult to get most wireless charging products to generate and actually provide the 5 watts or more needed to charge a smartphone.

"It's easy to make a demo that looks like you're charging your phone from 15 feet away. What really matters is the data." He said. "If you're just transmitting milliwatt-level power to a device that needs 5W of power, it's basically useless. Using magnetic induction, you can get 5 watts of charging power, but some appliances consume 2.4 kilowatts, and laptops and drones consume between 60 and 100 watts. Charging at a distance can help you realize your dream of never needing to charge again, but the ideal is rich and the reality is thin. We are far from solving the problem of higher power wireless charging."

Advantages of wireless charging

Consumers' desire to get rid of the inconvenience of charging plugs helped push shipments of consumer goods that support wireless charging up 40 percent to about 500 million units in 2017, according to a report released in February by ihsmarkit.com. By 2022, there will be 90 million smartphones equipped with wireless charging capabilities.

2014 is the first year of wireless charging for smart phones. At the time, starbucks installed PowerMat's charging pad, which USES the PMA standard (now managed by AirFuelAlliance), and McDonald's installed chargers that support the competitive Qi standard in its 50 stores in the UK. This also reflects the divergence of wireless charging standards, with samsung and AT&T supporting PMA and philips, qualcomm and nokia supporting the wireless charging alliance's Qi.

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Apple's decision last year to support the Qi standard in a new device tipped the balance of power between the two competing standards, a battle that ended with the announcement on Jan. 8 of an agreement to integrate the two standards. The IHSMarkit report predicts that samsung and apple's adoption of a common wireless charging standard will encourage other handset makers to join in and further boost user Numbers.

Remote charging

Another big news comes from the FCC, * recently, which approved two products that support wireless charging over long distances -- one at 3 feet, the other at 80 feet. None of the commercial products currently available to charge smartphone batteries is more than a few inches long.

In December, the FCC approved the WattUp, a radio frequency based one-to-many charging unit that can charge a device at a distance of three feet using 900MhZ and 5.8ghz.

It is also certified for the Powermat PowerSpot 3-watt transmitter, which USES radio frequency technology and can be recharged from a distance of up to 80 feet. It USES 915MHz, normally reserved for ISM, and ranges from 850 to 950MHz, which is a more typical band for UHFRFID products.

According to VictoriaFodale, who wrote the IHSMarkit report, a number of technical and regulatory issues make it difficult to estimate when we will see commercial wireless charging over long distances.
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"There is no commercial value in today's products for wireless charging over long distances, because there are so many trade-offs involved," Solis said. It's not a perfect solution, but if you can continue to use the device within a few feet, even if it's just a trickle of charge that helps slow down the battery drain, that's a great thing."

Energy levels in wireless charging applications drop so quickly that it is difficult to maintain signal strength beyond a few feet. According to Teffer, this would also require increasing the signal's power to such a high level that it would violate local broadcasting regulations and even safety regulations. It is difficult to find a good balance between power, safety and efficiency.

"A phone that supports wireless charging over long distances is the industry's holy grail," says CharlesGreene, chief operating officer and chief technology officer at Powercast. Powercast is one of two companies that recently won FCC approval to sell products that support charging phone batteries from 5 to 10 feet away.

"Physical properties do cause some limitations," Greene says. "As you get further and further away from the power source, the power goes down. There are ways around this, but they will narrow the range of charges and make it more difficult to create an area where you can do one-to-many charging, which is what we're focusing on."

Powercast has adopted the Qi standard for smartphone charging, but it hasn't abandoned its own RF charging technology. Instead, it is developing a qi-enabled phone charger and integrating it into its own transmitter, which could be available in the third quarter of this year.

"The Qi standard is really very mature, but it has its limitations," says Greene. Typically, it is a one-to-one rather than a one-to-many solution, and it requires a power board. We were able to provide a combination of other solutions. Transmitter through the surface of the table, we can overnight (from a distance) to provide mobile phone 10% to 15% of the battery, we can further improve, to 50%, so that I can put the transmitter on my bedside table or on the table, it can continuous charge their phone all day, maybe will never need to plug in the cable charger."

WiTricity CTOMorrisKesler said, Wireless Charger is sure to achieve higher power than today, and at least in the short to achieve one-to-many charging, WiTricity is hatched from the Massachusetts institute of technology in 2007 of a company, aimed at the MIT professor MarinSolja č I level research results into commercial magnetic resonance wireless transmission.

WiTricity says it will offer rechargeable parking MATS later this year to be sold as an accessory for a carmaker * high-end electric cars. Depending on the size of the vehicle, the system can provide 3.6kw to 11kw of power with an efficiency of up to 93%. It can transmit power over a range of a few meters, allowing owners to park their cars normally, rather than having to park them within a few centimeters of the parking mat.

"How far the power can travel depends on the size of the transmitter and receiver and your power level, but one of the advantages of mri is the ability to make one-to-many connections," says Kesler. "The body doesn't react too much to magnetic fields, so there's no need to worry about the effects of mri on the body. If you're trying to send energy in a room of about 10 meters, you might want to use an antenna to send the signal to a specific location."

He said there was no reason to think of mobile phones as a market for wireless charging. Although the market for electric vehicles (evs) is still in its infancy, broadly speaking, many factories and warehouses have automated ground vehicles, industrial machinery, and virtually anything that USES electricity and can move is a potential market for wireless charging, as well as medical applications and implants.

"You have to be careful about efficiency," he said. "If you're going to use a kilowatt at 70 percent efficiency, you're going to have to deal with 300 watts of heat consumption, which is a tricky problem."

Beat Regards,

Ada Zheng