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Inductive charging (also known as wireless charging or cordless charging) is a type of wireless power transfer. It uses electromagnetic induction to provide electricity to portable devices. Inductive charging is also used in vehicles, power tools, electric toothbrushes, and medical devices. The portable equipment can be placed near a charging station or inductive pad without needing to be precisely aligned or make electrical contact with a dock or plug.

Inductive charging is named so because it transfers energy through inductive coupling. First, alternating current passes through an induction coil in the charging station or pad. The moving electric charge creates a magnetic field, which fluctuates in strength because the electric current’s amplitude is fluctuating. This changing magnetic field creates an alternating electric current in the portable device’s induction coil, which in turn passes through a rectifier to convert it to direct current. Finally, the direct current charges a battery or provides operating power.^[1][2]

Greater distances between sender and receiver coils can be achieved when the inductive charging system uses resonant inductive coupling, where a capacitor is added to each induction coil to create two LC circuits with a specific resonance frequency. The frequency of the alternating current is matched with the resonance frequency, and the frequency is chosen depending on the distance desired for peak efficiency.^[1] Recent improvements to this resonant system include using a movable transmission coil (i.e., mounted on an elevating platform or arm) and the use of other materials for the receiver coil such as silver-plated copper or sometimes aluminum to minimize weight and decrease resistance due to the skin effect.

History[edit]

Induction power transfer was first used in 1894 when M. Hutin and M. Le-Blanc proposed an apparatus and method to power an electric vehicle.^[3] However, combustion engines proved more popular, and this technology was forgotten for a time.^[2]

In 1972, Professor Don Otto of the University of Auckland proposed a vehicle powered by induction using transmitters in the road and a receiver on the vehicle.^[2] In 1977, John E. Trombly was awarded a patent for an «Electromagnetically coupled battery charger.» The patent describes an application to charge headlamp batteries for miners (US 4031449). The first application of inductive charging used in the United States was performed by J.G. Bolger, F.A. Kirsten, and S. Ng in 1978. They made an electric vehicle powered with a system at 180 Hz with 20 kW.^[2] In California in the 1980s, a bus was produced, which was powered by inductive charging, and similar work was being done in France and Germany around this time.^[2]

In 2006, MIT began using^{[clarification needed]} resonant coupling. They were able to transmit a large amount of power without radiation over a few meters. This proved to be better for commercial needs, and it was a major step for inductive charging.^{[2][failed verification]}

The Wireless Power Consortium (WPC) was established in 2008, and in 2010 they established the Qi standard. In 2012, the Alliance for Wireless Power (A4WP) and the Power Matter Alliance (PMA) were founded. Japan established Broadband Wireless Forum (BWF) in 2009, and they established the Wireless Power Consortium for Practical Applications (WiPoT) in 2013. The Energy Harvesting Consortium (EHC) was also founded in Japan in 2010. Korea established the Korean Wireless Power Forum (KWPF) in 2011.^[2] The purpose of these organizations is to create standards for inductive charging. In 2018, The Qi Wireless Standard was adopted for use in military equipment in North Korea, Russia, and Germany

Application areas[edit]

Applications of inductive charging can be divided into two broad categories: Low power and high power:

• Low power applications are generally supportive of small consumer electronic devices such as cell phones, handheld devices, some computers, and similar devices which normally charge at power levels below 100 watts. Typically, the AC utility frequency of 50 or 60 Hertz is used.^[4]
• High power inductive charging generally refers to inductive charging of batteries at power levels above 1 kilowatt. The most prominent application area for high power inductive charging is in support of electric vehicles, where inductive charging provides an automated and cordless alternative to plug-in charging. Power levels of these devices can range from approximately 1 kilowatt to 300 kilowatts or higher. All high-power inductive charging systems use resonated primary and secondary coils. These systems work in the long wave range with frequencies up to 130 kHz. The use of short wave frequencies can enhance the system’s efficiency and size^[5] but would eventually transmit the signal worldwide. High powers raise the concern of electromagnetic compatibility and radio frequency interference.

Advantages[edit]

• Protected connections – No corrosion when the electronics are enclosed, away from water or oxygen in the atmosphere. Less risk of electrical faults such as short circuits due to insulation failure, especially where connections are made or broken frequently.^[6]
• Low infection risk – For embedded medical devices, the transmission of power via a magnetic field passing through the skin avoids the infection risks associated with wires penetrating the skin.^[7]
• Durability – Without the need to constantly plug and unplug the device, there is significantly less wear and tear on the socket of the device and the attaching cable.^[6]
• Increased convenience and aesthetic quality – No need for cables.
• Automated high power inductive charging of electric vehicles allows for more frequent charging events and consequently an extension of driving range.
• Inductive charging systems can be operated automatically without dependence on people to plug and unplug. This results in higher reliability.
• Automatic operation of inductive charging in roads theoretically allows vehicles to run indefinitely.^[8]

Disadvantages[edit]

The following disadvantages have been noted for low-power (i.e., less than 100 watts) inductive charging devices, and may not apply to high-power (i.e., greater than 5 kilowatts) electric vehicle inductive charging systems.^{[citation needed]}

• Slower charging – Due to the lower efficiency, devices take 15 percent longer to charge when supplied power is the same amount.^[9]
• More expensive – Inductive charging also requires drive electronics and coils in both device and charger, increasing the complexity and cost of manufacturing.^[10][11]
• Inconvenience – When a mobile device is connected to a cable, it can be moved around (albeit in a limited range) and operated while charging. In most implementations of inductive charging, the mobile device must be left on a pad to charge, and thus can’t be moved around or easily operated while charging. With some standards, charging can be maintained at a distance, but only with nothing present between the transmitter and receiver.^[6]
• Compatible standards – Not all devices are compatible with different inductive chargers. However, some devices have started to support multiple standards.

Inefficiency has other costs besides longer charge times. Inductive chargers produce more waste heat than wired chargers, which may negatively impact battery longevity.^{[13][better source needed]} An amateur 2020 analysis of energy use conducted with a Pixel 4 found that a wired charge from 0 to 100 percent consumed 14.26 Wh (watt-hours), while a wireless charging stand used 19.8 Wh, an increase of 39%. Using a generic brand wireless charging pad and mis-aligning the phone produced consumption up to 25.62 Wh, or an 80% increase. The analysis noted that while this is not likely to be noticeable to individuals, it has negative implications for greater adoption of smartphone wireless charging.^[14]

Newer approaches reduce transfer losses through the use of ultra thin coils, higher frequencies, and optimized drive electronics. This results in more efficient and compact chargers and receivers, facilitating their integration into mobile devices or batteries with minimal changes required.^[15][16] These technologies provide charging times comparable to wired approaches, and they are rapidly finding their way into mobile devices.

Safety[edit]

An increase in high-power inductive charging devices has led to researchers looking into the safety factor of the electromagnetic fields (EMF) put off by larger inductor coils. With the recent interest in the expansion of high power inductive charging with electric cars, an increase in health and safety concerns has arisen. To provide a larger distance of coverage you would in return need a larger coil for your inductor. An electric car with this size conductor would need about 300 kW from a 400 V battery to emit enough charge.^{[clarification needed]} This much exposure to the skin of a human could prove harmful if not met within the right conditions. Exposure limits can be satisfied even when the transmitter coil is very close to the body.^[17]

Testing has been done on how organs can be affected by these fields when put under low levels of frequency from these fields. When exposed to various levels of frequencies you can experience dizziness, light flashes, or tingling through nerves. At higher ranges, you can experience heating or even burning of the skin. Most people experience low EMF in everyday life. The most common place to experience these frequencies is with a wireless charger, usually on a nightstand located near the head.^[18]

Standards[edit]

Standards refer to the different set operating systems with which devices are compatible. There are two main standards: Qi and PMA.^[12] The two standards operate very similarly, but they use different transmission frequencies and connection protocols.^[12] Because of this, devices compatible with one standard are not necessarily compatible with the other standard. However, there are devices compatible with both standards.

• Magne Charge, a largely obsolete inductive charging system, also known as J1773, used to charge battery electric vehicles (BEV) formerly made by General Motors.
• The emerging SAE J2954 standard allows inductive car charging over a pad, with power delivery up to 11 kW.^[19]
• Qi, an interface standard developed by the Wireless Power Consortium for inductive electrical power transfer. At the time of July 2017, it is the most popular standard in the world, with more than 200 million devices supporting this interface.
• AirFuel Alliance:
  • In January 2012, the IEEE announced the initiation of the Power Matters Alliance (PMA) under the IEEE Standards Association (IEEE-SA) Industry Connections. The alliance is formed to publish a set of standards for inductive power that are safe and energy-efficient, and have smart power management. The PMA will also focus on the creation of an inductive power ecosystem^[20]
  • Rezence was an interface standard developed by the Alliance for Wireless Power (A4WP).
  • A4WP and PMA merged into the AirFuel Alliance in 2015.^[21]

Electronic devices[edit]

Many manufacturers of smartphones have started adding this technology into their devices, the majority adopting the Qi wireless charging standard. Major manufacturers such as Apple and Samsung produce many models of their phones in high volume with Qi capabilities. The popularity of the Qi standard has driven other manufacturers to adopt this as their own standard.^[22] Smartphones have become the driving force of this technology entering consumers’ homes, where many household technologies have been developed to utilize this technology.

Samsung and other companies have begun exploring the idea of «surface charging», building an inductive charging station into an entire surface such as a desk or table.^[22] Contrarily, Apple and Anker are pushing a dock-based charging platform. This includes charging pads and disks that have a much smaller footprint. These are geared for consumers who wish to have smaller chargers that would be located in common areas and blend in with the current décor of their home.^[22] Due to the adoption of the Qi standard of wireless charging, any of these chargers will work with any phone as long as it is Qi capable.^[22]

Another development is reverse wireless charging, which allows a mobile phone to wirelessly discharge its own battery into another device.^[23]

Examples[edit]

• Oral-B rechargeable toothbrushes by the Braun company have used inductive charging since the early 1990s.
• At the Consumer Electronics Show (CES) in January 2007, Visteon unveiled its inductive charging system for in-vehicle use that could charge only specially made cell phones to MP3 players with compatible receivers.^[24]
• April 28, 2009: An Energizer inductive charging station for the Wii remote was reported on IGN.^[25]
• At CES in January 2009, Palm, Inc. announced its new Pre smartphone would be available with an optional inductive charger accessory, the «Touchstone». The charger came with a required special backplate that became standard on the subsequent Pre Plus model announced at CES 2010. This was also featured on later Pixi, Pixi Plus, and Veer 4G smartphones. Upon launch in 2011, the ill-fated HP Touchpad tablet (after HP’s acquisition of Palm Inc.) had a built in touchstone coil that doubled as an antenna for its NFC-like Touch to Share feature.^[15][26][27]
• March 24, 2013: Samsung launched the Galaxy S3, which supports an optionally retrofittable back cover accessory, included in their separate “Wireless Charging Kit”.
• Nokia announced on September 5, 2012, the Lumia 920 and Lumia 820, which supports respectively integrate inductive charging and inductive charging with an accessory back.
• March 15, 2013: Samsung launched the Galaxy S4, which supports inductive charging with an accessory back cover.
• July 26, 2013: Google and ASUS launched the Nexus 7 2013 Edition with integrated inductive charging.
• September 9, 2014: Apple announced Apple Watch (released on April 24, 2015), which uses wireless inductive charging.
• September 12, 2017: Apple announced the AirPower wireless charging mat. It was meant to be capable of charging an iPhone, an Apple Watch, and AirPods simultaneously; the product however was never released. On September 12, 2018, Apple removed most mentions of the AirPower from its website and on March 29, 2019, it canceled the product completely.^[28]

Qi devices[edit]

• Nokia launched two smartphones (the Lumia 820 and Lumia 920) on 5 September 2012, which feature Qi inductive charging.^[29]
• Google and LG launched the Nexus 4 in October 2012 which supports inductive charging using the Qi standard.
• Motorola Mobility launched its Droid 3 and Droid 4, both optionally support the Qi standard.
• On November 21, 2012 HTC launched the Droid DNA, which also supports the Qi standard.
• October 31, 2013 Google and LG launched the Nexus 5, which supports inductive charging with Qi.
• April 14, 2014 Samsung launched the Galaxy S5 that supports Qi wireless charging with either a wireless charging back or receiver.
• November 20, 2015 Microsoft launched the Lumia 950 XL and Lumia 950 which support charging with the Qi standard.
• February 22, 2016 Samsung announced its new flagship Galaxy S7 and S7 Edge which use an interface that is almost the same as Qi. The Samsung Galaxy S8 and Samsung Galaxy Note 8 released in 2017 also feature Qi wireless charging technology.
• September 12, 2017 Apple announced that the iPhone 8 and iPhone X would feature wireless Qi standard charging.

Furniture[edit]

• Ikea has a series of wireless charging furniture that supports the Qi standard.

Dual standard[edit]

• March 3, 2015: Samsung announced its new flagship Galaxy S6 and S6 Edge with wireless inductive charging through both Qi and PMA compatible chargers. All phones in the Samsung Galaxy S and Note lines following the S6 have supported wireless charging.
• November 6, 2015 BlackBerry released its new flagship BlackBerry Priv, the first BlackBerry phone to support wireless inductive charging through both Qi and PMA compatible chargers.

Research and other[edit]

• Transcutaneous Energy Transfer (TET) systems in artificial hearts and other surgically implanted devices.
• In 2006, researchers at the Massachusetts Institute of Technology reported that they had discovered an efficient way to transfer power between coils separated by a few meters. The team, led by Marin Soljačić, theorized that they could extend the distance between the coils by adding resonance to the equation. The MIT inductive power project, called WiTricity, uses a curved coil and capacitive plates.^[30][31]
• In 2012 the Russian private museum Grand Maket Rossiya opened featuring inductive charging on its model car exhibits.
• As of 2017, Disney Research has been developing and researching room-scale inductive charging for multiple devices.

Transportation[edit]

Electric vehicle wireless power transfer or wireless charging is generally divided into three categories: stationary charging when the vehicle is parked for an extended period of time; dynamic charging when the vehicle is driven on roads or highways; and quasi-dynamic or semi-dynamic charging, when the vehicle moves at low speeds between stops,^[32]: 847 for example when a taxi slowly drives at a taxi rank.^[33] Inductive charging is not considered a mature dynamic charging technology as it delivers the least power of the three electric road technologies, its receivers lose 20%-25% of the supplied power when installed on trucks, and its health effects have yet to be documented, according to a French government working group on electric roads.^[34]

Stationary charging[edit]

In one inductive charging system, one winding is attached to the underside of the car, and the other stays on the floor of the garage.^[35] The major advantage of the inductive approach for vehicle charging is that there is no possibility of electric shock, as there are no exposed conductors, although interlocks, special connectors and RCDs (ground fault interruptors, or GFIs) can make conductive coupling nearly as safe. An inductive charging proponent from Toyota contended in 1998 that overall cost differences were minimal, while a conductive charging proponent from Ford contended that conductive charging was more cost efficient.^[36]

From 2010 onwards car makers signaled interest in wireless charging as another piece of the digital cockpit. A group was launched in May 2010 by the Consumer Electronics Association to set a baseline for interoperability for chargers. In one sign of the road ahead a General Motors executive is chairing the standards, effort group. Toyota and Ford managers said they also are interested in the technology and the standards effort.^[37]

Daimler’s Head of Future Mobility, Professor Herbert Kohler, however, has expressed caution and said the inductive charging for EVs is at least 15 years away (from 2011) and the safety aspects of inductive charging for EVs have yet to be looked into in greater detail. For example, what would happen if someone with a pacemaker is inside the vehicle? Another downside is that the technology requires a precise alignment between the inductive pick-up and the charging facility.^[38]

In November 2011, the Mayor of London, Boris Johnson, and Qualcomm announced a trial of 13 wireless charging points and 50 EVs in the Shoreditch area of London’s Tech City, due to be rolled out in early 2012.^[39][40] In October 2014, the University of Utah in Salt Lake City, Utah added an electric bus to its mass transit fleet that uses an induction plate at the end of its route to recharge.^[41] UTA, the regional public transportation agency, plans to introduce similar buses in 2018.^[42] In November 2012 wireless charging was introduced with 3 buses in Utrecht, The Netherlands. January 2015, eight electric buses were introduced to Milton Keynes, England, which uses inductive charging in the road with proov/ipt technology at either end of the journey to prolong overnight charges.,^[43] Later bus routes in Bristol, London and Madrid followed.

Dynamic charging[edit]

The first working prototype of an electric vehicle that charges wirelessly while driving, which is known as «dynamic wireless charging» or «dynamic wireless power transfer», is generally regarded to have been developed at the University of California, Berkeley in the 1980s and 1990s. The first commercialized dynamic wireless charging system, Online Electric Vehicle (OLEV), was developed as early as 2009 by researchers at the Korea Advanced Institute of Science and Technology (KAIST).^[32]: 848 Vehicles using the system draw power from a power source underneath the road surface, which is an array of inductive rails or coils.^[44][45] Commercialization efforts of the technology have not been successful because of high costs,^[46] and its main technical challenge is low efficiency.^[47]: 57 Dynamic inductive charging infrastructure was found to increase the occurrence of reflective cracks in road surfaces.^{[47]: 64 [48]} As of 2021, companies and organizations such as Vedecom,^[49] Magment, Electreon, and IPT are developing dynamic inductive coil charging technologies.^[50] IPT is additionally developing a system that uses inductive rails instead of coils, as the current standards which use coils are «extremely expensive» for dynamic charging, according to the CEO of IPT.^[51]

Research and development[edit]

Work and experimentation is currently underway in designing this technology to be applied to electric vehicles. This could be implemented by using a predefined path or conductors that would transfer power across an air gap and charge the vehicle on a predefined path such as a wireless charging lane.^[52] Vehicles that could take advantage of this type of wireless charging lane to extend the range of their onboard batteries are already on the road.^[52] Some of the issues that are currently preventing these lanes from becoming widespread is the initial cost associated with installing this infrastructure that would benefit only a small percentage of vehicles currently on the road. Another complication is tracking how much power each vehicle was consuming/pulling from the lane. Without a commercial way to monetize this technology, many cities have already turned down plans to include these lanes in their public works spending packages.^[52] However this doesn’t mean that cars are unable to utilize large scale wireless charging. The first commercial steps are already being taken with wireless mats that allow electric vehicles to be charged without a corded connection while parked on a charging mat.^[52] These large scale projects have come with some issues which include the production of large amounts of heat between the two charging surfaces and may cause a safety issue.^[53] Currently companies are designing new heat dispersion methods by which they can combat this excess heat. These companies include most major electric vehicle manufacturers, such as Tesla, Toyota, and BMW.^[54]

Examples[edit]

• EPCOT Universe of Energy is equipped with moving theater «pews,» which take passengers/viewers through the exhibit. They are self-propelled, and inductively recharged when at rest.^[55] This exhibit with the recharging technology was in place ca. 2003.
• Hughes Electronics developed the Magne Charge interface for General Motors. The General Motors EV1 electric car was charged by inserting an inductive charging paddle into a receptacle on the vehicle. General Motors and Toyota agreed on this interface and it was also used in the Chevrolet S-10 EV and Toyota RAV4 EV vehicles.
• September 2015 Audi Wireless Charging (AWC) presented a 3.6 kW inductive charger^[56] during the 66th International Motor Show (IAA) 2015.
• September 17, 2015 Bombardier-Transportation PRIMOVE presented a 3.6 kW Charger for cars,^[57] which was developed at Site in Mannheim Germany.^[58]
• Transport for London has introduced inductive charging in a trial for double-decker buses in London.^[59]
• Magne Charge inductive charging was employed by several types of electric vehicles around 1998, but was discontinued^[60] after the California Air Resources Board selected the SAE J1772-2001, or «Avcon», conductive charging interface^[61] for electric vehicles in California in June 2001.^[62]
• In 1997 Conductix Wampler started with wireless charging in Germany, In 2002 20 buses started in operation In Turin with 60 kW charging. In 2013 the IPT technology was bought by Proov. In 2008 the technology was already used in the house of the future in Berlin with Mercedes A Class. Later Evatran also began development of Plugless Power, an inductive charging system it claims is the world’s first hands-free, plugless, proximity charging system for Electric Vehicles.^[63] With the participation of the local municipality and several businesses, field trials were begun in March 2010. The first system was sold to Google in 2011 for employee use at the Mountain View campus.^[64]
• Evatran began selling the Plugless L2 Wireless charging system to the public in 2014.^[65]
• Volvo Group invested in January 2019 in U.S.-based wireless charging specialist Momentum Dynamics.^[66] Volvo and Momentum Dynamics will run a three-year pilot project, starting in 2022, for wireless charging of electric taxis in taxi ranks.^[67]
• BRUSA Elektronik AG, a specialist provider and development company for electric vehicles, offers a wireless charging module named ICS with 3.7 kW power.^[68]
• A partnership between Cabonline, Jaguar, Momentum Dynamics, and Fortum Recharge is launching a wireless charging taxi fleet in Oslo, Norway. The fleet consists of 25 Jaguar I-Pace SUVs equipped with inductive charging pads rated at 50-75 kW. The pads use resonant inductive coupling operating at 85 Hz to improve wireless charging efficiency and range.^[69]
• On February 3, 2022, Hyundai Motor Group developed a wireless charging system for electric vehicles using the principle of magnetic induction.^[70] Power is transmitted to the vehicle through resonance between the magnetic pad at the bottom of the charging space and the magnetic pad at the bottom of the vehicle. The transmitted power is stored in the battery through a converter in the vehicle system. It was applied on a trial basis at Genesis Motor EV charging station located in South Korea.^[71]

Medical implications[edit]

Wireless charging is making an impact in the medical sector by means of being able to charge implants and sensors long-term that is located beneath the skin. Multiple companies offer rechargeable medical implant (e.g. implantable neurostimulators) which use inductive charging. Researchers have been able to print wireless power transmitting antenna on flexible materials that could be placed under the skin of patients.^[53] This could mean that under skin devices that could monitor the patient status could have a longer-term life and provide long observation or monitoring periods that could lead to better diagnosis from doctors. These devices may also make charging devices like pacemakers easier on the patient rather than having an exposed portion of the device pushing through the skin to allow corded charging. This technology would allow a completely implanted device making it safer for the patient. It is unclear if this technology will be approved for use – more research is needed on the safety of these devices.^[53] While these flexible polymers are safer than ridged sets of diodes they can be more susceptible to tearing during either placement or removal due to the fragile nature of the antenna that is printed on the plastic material. While these medical based applications seem very specific the high-speed power transfer that is achieved with these flexible antennas is being looked at for larger broader applications.^[53]

See also[edit]

References[edit]

External links[edit]

• How Inductors Work
• How Electric Toothbrushes Recharge Using Inductors
• Wireless Electricity Is Here
• Wireless charging
• Electric Bus Rapidly Recharges Using Wireless Charge Plates at Stops Archived 2016-03-07 at the Wayback Machine – Wired
• Tesla Tower – Inductive charging in year 1900
• Wireless Qi Charger, DiodeGoneWild on YouTube 16 August 2017

Inductive charging (also known as wireless charging or cordless charging) is a type of wireless power transfer. It uses electromagnetic induction to provide electricity to portable devices. Inductive charging is also used in vehicles, power tools, electric toothbrushes, and medical devices. The portable equipment can be placed near a charging station or inductive pad without needing to be precisely aligned or make electrical contact with a dock or plug.

Inductive charging is named so because it transfers energy through inductive coupling. First, alternating current passes through an induction coil in the charging station or pad. The moving electric charge creates a magnetic field, which fluctuates in strength because the electric current’s amplitude is fluctuating. This changing magnetic field creates an alternating electric current in the portable device’s induction coil, which in turn passes through a rectifier to convert it to direct current. Finally, the direct current charges a battery or provides operating power.^[1][2]

Greater distances between sender and receiver coils can be achieved when the inductive charging system uses resonant inductive coupling, where a capacitor is added to each induction coil to create two LC circuits with a specific resonance frequency. The frequency of the alternating current is matched with the resonance frequency, and the frequency is chosen depending on the distance desired for peak efficiency.^[1] Recent improvements to this resonant system include using a movable transmission coil (i.e., mounted on an elevating platform or arm) and the use of other materials for the receiver coil such as silver-plated copper or sometimes aluminum to minimize weight and decrease resistance due to the skin effect.

History[edit]

Induction power transfer was first used in 1894 when M. Hutin and M. Le-Blanc proposed an apparatus and method to power an electric vehicle.^[3] However, combustion engines proved more popular, and this technology was forgotten for a time.^[2]

In 1972, Professor Don Otto of the University of Auckland proposed a vehicle powered by induction using transmitters in the road and a receiver on the vehicle.^[2] In 1977, John E. Trombly was awarded a patent for an «Electromagnetically coupled battery charger.» The patent describes an application to charge headlamp batteries for miners (US 4031449). The first application of inductive charging used in the United States was performed by J.G. Bolger, F.A. Kirsten, and S. Ng in 1978. They made an electric vehicle powered with a system at 180 Hz with 20 kW.^[2] In California in the 1980s, a bus was produced, which was powered by inductive charging, and similar work was being done in France and Germany around this time.^[2]

In 2006, MIT began using^{[clarification needed]} resonant coupling. They were able to transmit a large amount of power without radiation over a few meters. This proved to be better for commercial needs, and it was a major step for inductive charging.^{[2][failed verification]}

The Wireless Power Consortium (WPC) was established in 2008, and in 2010 they established the Qi standard. In 2012, the Alliance for Wireless Power (A4WP) and the Power Matter Alliance (PMA) were founded. Japan established Broadband Wireless Forum (BWF) in 2009, and they established the Wireless Power Consortium for Practical Applications (WiPoT) in 2013. The Energy Harvesting Consortium (EHC) was also founded in Japan in 2010. Korea established the Korean Wireless Power Forum (KWPF) in 2011.^[2] The purpose of these organizations is to create standards for inductive charging. In 2018, The Qi Wireless Standard was adopted for use in military equipment in North Korea, Russia, and Germany

Application areas[edit]

Applications of inductive charging can be divided into two broad categories: Low power and high power:

• Low power applications are generally supportive of small consumer electronic devices such as cell phones, handheld devices, some computers, and similar devices which normally charge at power levels below 100 watts. Typically, the AC utility frequency of 50 or 60 Hertz is used.^[4]
• High power inductive charging generally refers to inductive charging of batteries at power levels above 1 kilowatt. The most prominent application area for high power inductive charging is in support of electric vehicles, where inductive charging provides an automated and cordless alternative to plug-in charging. Power levels of these devices can range from approximately 1 kilowatt to 300 kilowatts or higher. All high-power inductive charging systems use resonated primary and secondary coils. These systems work in the long wave range with frequencies up to 130 kHz. The use of short wave frequencies can enhance the system’s efficiency and size^[5] but would eventually transmit the signal worldwide. High powers raise the concern of electromagnetic compatibility and radio frequency interference.

Advantages[edit]

• Protected connections – No corrosion when the electronics are enclosed, away from water or oxygen in the atmosphere. Less risk of electrical faults such as short circuits due to insulation failure, especially where connections are made or broken frequently.^[6]
• Low infection risk – For embedded medical devices, the transmission of power via a magnetic field passing through the skin avoids the infection risks associated with wires penetrating the skin.^[7]
• Durability – Without the need to constantly plug and unplug the device, there is significantly less wear and tear on the socket of the device and the attaching cable.^[6]
• Increased convenience and aesthetic quality – No need for cables.
• Automated high power inductive charging of electric vehicles allows for more frequent charging events and consequently an extension of driving range.
• Inductive charging systems can be operated automatically without dependence on people to plug and unplug. This results in higher reliability.
• Automatic operation of inductive charging in roads theoretically allows vehicles to run indefinitely.^[8]

Disadvantages[edit]

The following disadvantages have been noted for low-power (i.e., less than 100 watts) inductive charging devices, and may not apply to high-power (i.e., greater than 5 kilowatts) electric vehicle inductive charging systems.^{[citation needed]}

• Slower charging – Due to the lower efficiency, devices take 15 percent longer to charge when supplied power is the same amount.^[9]
• More expensive – Inductive charging also requires drive electronics and coils in both device and charger, increasing the complexity and cost of manufacturing.^[10][11]
• Inconvenience – When a mobile device is connected to a cable, it can be moved around (albeit in a limited range) and operated while charging. In most implementations of inductive charging, the mobile device must be left on a pad to charge, and thus can’t be moved around or easily operated while charging. With some standards, charging can be maintained at a distance, but only with nothing present between the transmitter and receiver.^[6]
• Compatible standards – Not all devices are compatible with different inductive chargers. However, some devices have started to support multiple standards.

Inefficiency has other costs besides longer charge times. Inductive chargers produce more waste heat than wired chargers, which may negatively impact battery longevity.^{[13][better source needed]} An amateur 2020 analysis of energy use conducted with a Pixel 4 found that a wired charge from 0 to 100 percent consumed 14.26 Wh (watt-hours), while a wireless charging stand used 19.8 Wh, an increase of 39%. Using a generic brand wireless charging pad and mis-aligning the phone produced consumption up to 25.62 Wh, or an 80% increase. The analysis noted that while this is not likely to be noticeable to individuals, it has negative implications for greater adoption of smartphone wireless charging.^[14]

Newer approaches reduce transfer losses through the use of ultra thin coils, higher frequencies, and optimized drive electronics. This results in more efficient and compact chargers and receivers, facilitating their integration into mobile devices or batteries with minimal changes required.^[15][16] These technologies provide charging times comparable to wired approaches, and they are rapidly finding their way into mobile devices.

Safety[edit]

An increase in high-power inductive charging devices has led to researchers looking into the safety factor of the electromagnetic fields (EMF) put off by larger inductor coils. With the recent interest in the expansion of high power inductive charging with electric cars, an increase in health and safety concerns has arisen. To provide a larger distance of coverage you would in return need a larger coil for your inductor. An electric car with this size conductor would need about 300 kW from a 400 V battery to emit enough charge.^{[clarification needed]} This much exposure to the skin of a human could prove harmful if not met within the right conditions. Exposure limits can be satisfied even when the transmitter coil is very close to the body.^[17]

Testing has been done on how organs can be affected by these fields when put under low levels of frequency from these fields. When exposed to various levels of frequencies you can experience dizziness, light flashes, or tingling through nerves. At higher ranges, you can experience heating or even burning of the skin. Most people experience low EMF in everyday life. The most common place to experience these frequencies is with a wireless charger, usually on a nightstand located near the head.^[18]

Standards[edit]

Standards refer to the different set operating systems with which devices are compatible. There are two main standards: Qi and PMA.^[12] The two standards operate very similarly, but they use different transmission frequencies and connection protocols.^[12] Because of this, devices compatible with one standard are not necessarily compatible with the other standard. However, there are devices compatible with both standards.

• Magne Charge, a largely obsolete inductive charging system, also known as J1773, used to charge battery electric vehicles (BEV) formerly made by General Motors.
• The emerging SAE J2954 standard allows inductive car charging over a pad, with power delivery up to 11 kW.^[19]
• Qi, an interface standard developed by the Wireless Power Consortium for inductive electrical power transfer. At the time of July 2017, it is the most popular standard in the world, with more than 200 million devices supporting this interface.
• AirFuel Alliance:
  • In January 2012, the IEEE announced the initiation of the Power Matters Alliance (PMA) under the IEEE Standards Association (IEEE-SA) Industry Connections. The alliance is formed to publish a set of standards for inductive power that are safe and energy-efficient, and have smart power management. The PMA will also focus on the creation of an inductive power ecosystem^[20]
  • Rezence was an interface standard developed by the Alliance for Wireless Power (A4WP).
  • A4WP and PMA merged into the AirFuel Alliance in 2015.^[21]

Electronic devices[edit]

Many manufacturers of smartphones have started adding this technology into their devices, the majority adopting the Qi wireless charging standard. Major manufacturers such as Apple and Samsung produce many models of their phones in high volume with Qi capabilities. The popularity of the Qi standard has driven other manufacturers to adopt this as their own standard.^[22] Smartphones have become the driving force of this technology entering consumers’ homes, where many household technologies have been developed to utilize this technology.

Samsung and other companies have begun exploring the idea of «surface charging», building an inductive charging station into an entire surface such as a desk or table.^[22] Contrarily, Apple and Anker are pushing a dock-based charging platform. This includes charging pads and disks that have a much smaller footprint. These are geared for consumers who wish to have smaller chargers that would be located in common areas and blend in with the current décor of their home.^[22] Due to the adoption of the Qi standard of wireless charging, any of these chargers will work with any phone as long as it is Qi capable.^[22]

Another development is reverse wireless charging, which allows a mobile phone to wirelessly discharge its own battery into another device.^[23]

Examples[edit]

• Oral-B rechargeable toothbrushes by the Braun company have used inductive charging since the early 1990s.
• At the Consumer Electronics Show (CES) in January 2007, Visteon unveiled its inductive charging system for in-vehicle use that could charge only specially made cell phones to MP3 players with compatible receivers.^[24]
• April 28, 2009: An Energizer inductive charging station for the Wii remote was reported on IGN.^[25]
• At CES in January 2009, Palm, Inc. announced its new Pre smartphone would be available with an optional inductive charger accessory, the «Touchstone». The charger came with a required special backplate that became standard on the subsequent Pre Plus model announced at CES 2010. This was also featured on later Pixi, Pixi Plus, and Veer 4G smartphones. Upon launch in 2011, the ill-fated HP Touchpad tablet (after HP’s acquisition of Palm Inc.) had a built in touchstone coil that doubled as an antenna for its NFC-like Touch to Share feature.^[15][26][27]
• March 24, 2013: Samsung launched the Galaxy S3, which supports an optionally retrofittable back cover accessory, included in their separate “Wireless Charging Kit”.
• Nokia announced on September 5, 2012, the Lumia 920 and Lumia 820, which supports respectively integrate inductive charging and inductive charging with an accessory back.
• March 15, 2013: Samsung launched the Galaxy S4, which supports inductive charging with an accessory back cover.
• July 26, 2013: Google and ASUS launched the Nexus 7 2013 Edition with integrated inductive charging.
• September 9, 2014: Apple announced Apple Watch (released on April 24, 2015), which uses wireless inductive charging.
• September 12, 2017: Apple announced the AirPower wireless charging mat. It was meant to be capable of charging an iPhone, an Apple Watch, and AirPods simultaneously; the product however was never released. On September 12, 2018, Apple removed most mentions of the AirPower from its website and on March 29, 2019, it canceled the product completely.^[28]

Qi devices[edit]

• Nokia launched two smartphones (the Lumia 820 and Lumia 920) on 5 September 2012, which feature Qi inductive charging.^[29]
• Google and LG launched the Nexus 4 in October 2012 which supports inductive charging using the Qi standard.
• Motorola Mobility launched its Droid 3 and Droid 4, both optionally support the Qi standard.
• On November 21, 2012 HTC launched the Droid DNA, which also supports the Qi standard.
• October 31, 2013 Google and LG launched the Nexus 5, which supports inductive charging with Qi.
• April 14, 2014 Samsung launched the Galaxy S5 that supports Qi wireless charging with either a wireless charging back or receiver.
• November 20, 2015 Microsoft launched the Lumia 950 XL and Lumia 950 which support charging with the Qi standard.
• February 22, 2016 Samsung announced its new flagship Galaxy S7 and S7 Edge which use an interface that is almost the same as Qi. The Samsung Galaxy S8 and Samsung Galaxy Note 8 released in 2017 also feature Qi wireless charging technology.
• September 12, 2017 Apple announced that the iPhone 8 and iPhone X would feature wireless Qi standard charging.

Furniture[edit]

• Ikea has a series of wireless charging furniture that supports the Qi standard.

Dual standard[edit]

• March 3, 2015: Samsung announced its new flagship Galaxy S6 and S6 Edge with wireless inductive charging through both Qi and PMA compatible chargers. All phones in the Samsung Galaxy S and Note lines following the S6 have supported wireless charging.
• November 6, 2015 BlackBerry released its new flagship BlackBerry Priv, the first BlackBerry phone to support wireless inductive charging through both Qi and PMA compatible chargers.

Research and other[edit]

• Transcutaneous Energy Transfer (TET) systems in artificial hearts and other surgically implanted devices.
• In 2006, researchers at the Massachusetts Institute of Technology reported that they had discovered an efficient way to transfer power between coils separated by a few meters. The team, led by Marin Soljačić, theorized that they could extend the distance between the coils by adding resonance to the equation. The MIT inductive power project, called WiTricity, uses a curved coil and capacitive plates.^[30][31]
• In 2012 the Russian private museum Grand Maket Rossiya opened featuring inductive charging on its model car exhibits.
• As of 2017, Disney Research has been developing and researching room-scale inductive charging for multiple devices.

Transportation[edit]

Electric vehicle wireless power transfer or wireless charging is generally divided into three categories: stationary charging when the vehicle is parked for an extended period of time; dynamic charging when the vehicle is driven on roads or highways; and quasi-dynamic or semi-dynamic charging, when the vehicle moves at low speeds between stops,^[32]: 847 for example when a taxi slowly drives at a taxi rank.^[33] Inductive charging is not considered a mature dynamic charging technology as it delivers the least power of the three electric road technologies, its receivers lose 20%-25% of the supplied power when installed on trucks, and its health effects have yet to be documented, according to a French government working group on electric roads.^[34]

Stationary charging[edit]

In one inductive charging system, one winding is attached to the underside of the car, and the other stays on the floor of the garage.^[35] The major advantage of the inductive approach for vehicle charging is that there is no possibility of electric shock, as there are no exposed conductors, although interlocks, special connectors and RCDs (ground fault interruptors, or GFIs) can make conductive coupling nearly as safe. An inductive charging proponent from Toyota contended in 1998 that overall cost differences were minimal, while a conductive charging proponent from Ford contended that conductive charging was more cost efficient.^[36]

From 2010 onwards car makers signaled interest in wireless charging as another piece of the digital cockpit. A group was launched in May 2010 by the Consumer Electronics Association to set a baseline for interoperability for chargers. In one sign of the road ahead a General Motors executive is chairing the standards, effort group. Toyota and Ford managers said they also are interested in the technology and the standards effort.^[37]

Daimler’s Head of Future Mobility, Professor Herbert Kohler, however, has expressed caution and said the inductive charging for EVs is at least 15 years away (from 2011) and the safety aspects of inductive charging for EVs have yet to be looked into in greater detail. For example, what would happen if someone with a pacemaker is inside the vehicle? Another downside is that the technology requires a precise alignment between the inductive pick-up and the charging facility.^[38]

In November 2011, the Mayor of London, Boris Johnson, and Qualcomm announced a trial of 13 wireless charging points and 50 EVs in the Shoreditch area of London’s Tech City, due to be rolled out in early 2012.^[39][40] In October 2014, the University of Utah in Salt Lake City, Utah added an electric bus to its mass transit fleet that uses an induction plate at the end of its route to recharge.^[41] UTA, the regional public transportation agency, plans to introduce similar buses in 2018.^[42] In November 2012 wireless charging was introduced with 3 buses in Utrecht, The Netherlands. January 2015, eight electric buses were introduced to Milton Keynes, England, which uses inductive charging in the road with proov/ipt technology at either end of the journey to prolong overnight charges.,^[43] Later bus routes in Bristol, London and Madrid followed.

Dynamic charging[edit]

The first working prototype of an electric vehicle that charges wirelessly while driving, which is known as «dynamic wireless charging» or «dynamic wireless power transfer», is generally regarded to have been developed at the University of California, Berkeley in the 1980s and 1990s. The first commercialized dynamic wireless charging system, Online Electric Vehicle (OLEV), was developed as early as 2009 by researchers at the Korea Advanced Institute of Science and Technology (KAIST).^[32]: 848 Vehicles using the system draw power from a power source underneath the road surface, which is an array of inductive rails or coils.^[44][45] Commercialization efforts of the technology have not been successful because of high costs,^[46] and its main technical challenge is low efficiency.^[47]: 57 Dynamic inductive charging infrastructure was found to increase the occurrence of reflective cracks in road surfaces.^{[47]: 64 [48]} As of 2021, companies and organizations such as Vedecom,^[49] Magment, Electreon, and IPT are developing dynamic inductive coil charging technologies.^[50] IPT is additionally developing a system that uses inductive rails instead of coils, as the current standards which use coils are «extremely expensive» for dynamic charging, according to the CEO of IPT.^[51]

Research and development[edit]

Work and experimentation is currently underway in designing this technology to be applied to electric vehicles. This could be implemented by using a predefined path or conductors that would transfer power across an air gap and charge the vehicle on a predefined path such as a wireless charging lane.^[52] Vehicles that could take advantage of this type of wireless charging lane to extend the range of their onboard batteries are already on the road.^[52] Some of the issues that are currently preventing these lanes from becoming widespread is the initial cost associated with installing this infrastructure that would benefit only a small percentage of vehicles currently on the road. Another complication is tracking how much power each vehicle was consuming/pulling from the lane. Without a commercial way to monetize this technology, many cities have already turned down plans to include these lanes in their public works spending packages.^[52] However this doesn’t mean that cars are unable to utilize large scale wireless charging. The first commercial steps are already being taken with wireless mats that allow electric vehicles to be charged without a corded connection while parked on a charging mat.^[52] These large scale projects have come with some issues which include the production of large amounts of heat between the two charging surfaces and may cause a safety issue.^[53] Currently companies are designing new heat dispersion methods by which they can combat this excess heat. These companies include most major electric vehicle manufacturers, such as Tesla, Toyota, and BMW.^[54]

Examples[edit]

• EPCOT Universe of Energy is equipped with moving theater «pews,» which take passengers/viewers through the exhibit. They are self-propelled, and inductively recharged when at rest.^[55] This exhibit with the recharging technology was in place ca. 2003.
• Hughes Electronics developed the Magne Charge interface for General Motors. The General Motors EV1 electric car was charged by inserting an inductive charging paddle into a receptacle on the vehicle. General Motors and Toyota agreed on this interface and it was also used in the Chevrolet S-10 EV and Toyota RAV4 EV vehicles.
• September 2015 Audi Wireless Charging (AWC) presented a 3.6 kW inductive charger^[56] during the 66th International Motor Show (IAA) 2015.
• September 17, 2015 Bombardier-Transportation PRIMOVE presented a 3.6 kW Charger for cars,^[57] which was developed at Site in Mannheim Germany.^[58]
• Transport for London has introduced inductive charging in a trial for double-decker buses in London.^[59]
• Magne Charge inductive charging was employed by several types of electric vehicles around 1998, but was discontinued^[60] after the California Air Resources Board selected the SAE J1772-2001, or «Avcon», conductive charging interface^[61] for electric vehicles in California in June 2001.^[62]
• In 1997 Conductix Wampler started with wireless charging in Germany, In 2002 20 buses started in operation In Turin with 60 kW charging. In 2013 the IPT technology was bought by Proov. In 2008 the technology was already used in the house of the future in Berlin with Mercedes A Class. Later Evatran also began development of Plugless Power, an inductive charging system it claims is the world’s first hands-free, plugless, proximity charging system for Electric Vehicles.^[63] With the participation of the local municipality and several businesses, field trials were begun in March 2010. The first system was sold to Google in 2011 for employee use at the Mountain View campus.^[64]
• Evatran began selling the Plugless L2 Wireless charging system to the public in 2014.^[65]
• Volvo Group invested in January 2019 in U.S.-based wireless charging specialist Momentum Dynamics.^[66] Volvo and Momentum Dynamics will run a three-year pilot project, starting in 2022, for wireless charging of electric taxis in taxi ranks.^[67]
• BRUSA Elektronik AG, a specialist provider and development company for electric vehicles, offers a wireless charging module named ICS with 3.7 kW power.^[68]
• A partnership between Cabonline, Jaguar, Momentum Dynamics, and Fortum Recharge is launching a wireless charging taxi fleet in Oslo, Norway. The fleet consists of 25 Jaguar I-Pace SUVs equipped with inductive charging pads rated at 50-75 kW. The pads use resonant inductive coupling operating at 85 Hz to improve wireless charging efficiency and range.^[69]
• On February 3, 2022, Hyundai Motor Group developed a wireless charging system for electric vehicles using the principle of magnetic induction.^[70] Power is transmitted to the vehicle through resonance between the magnetic pad at the bottom of the charging space and the magnetic pad at the bottom of the vehicle. The transmitted power is stored in the battery through a converter in the vehicle system. It was applied on a trial basis at Genesis Motor EV charging station located in South Korea.^[71]

Medical implications[edit]

Wireless charging is making an impact in the medical sector by means of being able to charge implants and sensors long-term that is located beneath the skin. Multiple companies offer rechargeable medical implant (e.g. implantable neurostimulators) which use inductive charging. Researchers have been able to print wireless power transmitting antenna on flexible materials that could be placed under the skin of patients.^[53] This could mean that under skin devices that could monitor the patient status could have a longer-term life and provide long observation or monitoring periods that could lead to better diagnosis from doctors. These devices may also make charging devices like pacemakers easier on the patient rather than having an exposed portion of the device pushing through the skin to allow corded charging. This technology would allow a completely implanted device making it safer for the patient. It is unclear if this technology will be approved for use – more research is needed on the safety of these devices.^[53] While these flexible polymers are safer than ridged sets of diodes they can be more susceptible to tearing during either placement or removal due to the fragile nature of the antenna that is printed on the plastic material. While these medical based applications seem very specific the high-speed power transfer that is achieved with these flexible antennas is being looked at for larger broader applications.^[53]

See also[edit]

References[edit]

External links[edit]

• How Inductors Work
• How Electric Toothbrushes Recharge Using Inductors
• Wireless Electricity Is Here
• Wireless charging
• Electric Bus Rapidly Recharges Using Wireless Charge Plates at Stops Archived 2016-03-07 at the Wayback Machine – Wired
• Tesla Tower – Inductive charging in year 1900
• Wireless Qi Charger, DiodeGoneWild on YouTube 16 August 2017

Индуктивные зарядные устройства существуют уже почти 10 лет, но популярной эта технология стала 2-3 года назад, когда возможность беспроводного заряда появилась в смартфонах Apple. В настоящее время эту функцию предлагают и многие другие производители мобильных устройств.

Как работает индуктивное зарядное устройство?

В нем используется явление электромагнитной индукции, т.е. преобразование энергии в проводнике за счет изменения магнитного поля. На практике это означает, что индуктивное зарядное устройство имеет небольшую катушку диаметром несколько сантиметров, через которую протекает ток и индуцирует магнитное поле. Это магнитное поле генерирует ток во второй катушке, установленной в смартфоне. К сожалению, из-за своих небольших размеров, катушки работают на расстоянии не более 4 см и обременены значительными энергетическими потерями.

Первые зарядные устройства стандарта Qi предлагали мощность зарядки 5 Вт, которая была увеличена до 10-15 Вт в 2015 году и даже до 30 Вт в 2017 году (но только в теории). Первые смартфоны, способные заряжать до 30 Вт, начали появляться только в этом году, среди них выделились Oppo и Oneplus.

Серьезным недостатком этой технологии, помимо потери энергии, является необходимость размещения смартфона в определенном месте, например, на специальном коврике для зарядки. Apple, в свое время, начала работать над зарядным устройством, которое бы могло одновременно заряжать смартфон, наушники в чехле и часы, но в конечном счете ничего из этого не вышло.

Другим ограничением индукционной технологии является необходимость использования пластикового или стеклянного корпуса, т.к. металл сдерживает магнитное поле и поэтому не подходит для индуктивного заряда. Это огромный минус, потому что пластик не относится к материалам класса “премиум”, а стекло по своей природе очень хрупкое. Но похоже, что пользователи смартфонов готовы закрыть на это глаза ради удобства.

На видео: Как работает беспроводная зарядка и насколько удобной она может быть?

Подходящая мощность

Подавляющее большинство смартфонов будет использовать максимум 10 Вт по нескольким причинам. Во-первых, чем выше мощность, тем больше проводится тепла, которое нужно рассеивать. Поэтому во многих телефонах устанавливают охлаждающие вентиляторы. Во-вторых, индуктивный заряд длится намного дольше, но не все пользователи нуждаются в быстром пополнении энергии и поэтому они могут не спеша заряжать свой телефон с помощью беспроводной технологии. Однако это не означает, что не существует быстрых беспроводных зарядных устройств.

Какое оборудование может использовать индуктивное зарядное устройство?
На самом деле, любое устройство, в котором можно установить маленькую катушку плотно обмотанную медным проводом, может использовать беспроводную зарядку. В последнее время появляется все больше продуктов, использующих эту технологию. К ним относятся смарт-часы, браслеты, а также беспроводные наушники.

Рекомендуемые модели индуктивных зарядных устройств

На рынке достаточно много беспроводных зарядных устройств, т.к. их популярность набирает обороты и каждый производитель смартфонов и аксессуаров старается внедрить востребованную технологию в свои устройства. Из недорогих моделей рекомендуется Wireless Charger 2 мощностью 10 Вт. С его помощью можно зарядить Qi-совместимые устройства мощностью 5, 7,5 и 10 Вт.

Аналогичные возможности предлагает беспроводная зарядная станция Xiaomi Mi, которая немного дороже и также может заряжать смартфоны и другие аксессуары мощностью 10 Вт. Если вам больше нравится круглый дизайн китайского производителя, то этот выбор может быть веским аргументом в пользу его покупки, хотя технически оба зарядных устройства идентичны.

Huawei CP60 – это зарядное устройство, которое поставляется вместе с Huawei Mate 20 Pro, предлагает 15 Вт. Оно также совместимо и с другими устройствами в пределах заданной мощности.

Любителям смартфонов Samsung рекомендуется Wireless Charger Convertible. Это довольно дорогой инструмент, который может заряжать телефон в двух положениях – горизонтально и на специальной подставке. Мощность зарядки 10 Вт, конечно, это немного, но большинство смартфонов Samsung все равно не могут использовать больше энергии.

Если у вас несколько устройств, способных заряжаться индуктивным методом, то стоит взглянуть на модели, которые имеют две катушки или более. Например, двойной беспроводной зарядный блок Mophie, способен заряжать сразу два устройства по беспроводной связи, а третье устройство с помощью кабеля через встроенный дополнительный разъем USB типа A. Максимальная мощность для него составляет 10 Вт.

Беспроводная зарядка позволяет питать гаджеты без необходимости подключать устройство непосредственно к розетке через гнездо-шнур-блок зарядки. В большинстве случаев смартфоны, поддерживающие беспроводную зарядку, необходимо размещать на небольшой плоской зарядной площадке или в док-станции. Хотя зарядная панель сама по себе должна быть подключена к электросети.

Как работает индуктивная зарядка и когда она была изобретена?

И пусть мы воспринимаем беспроводную зарядку как настоящий цифровой и технический, доступный широким массам пользователей, прорыв, все же корни изобретения тянутся от Николы Теслы. А если капнуть еще глубже, окажется, что индуктивная зарядка и вовсе используется еще с 1990-х годов в зубных щетках! Смартфоны используют ту же схему, что прародители современных зубных щеток. И телефон, и зарядная панель оснащены индукционными катушками (проще говоря, это железный сердечник, обернутый медной проволокой). Когда устройство помещается на беспроводную зарядную площадку, близость катушек позволяет создать электромагнитное поле. Оно, в свою очередь, передает электричество от одной катушки (зарядная панель) к другой (смартфон). Индукционная катушка в устройстве использует полученное электричество для зарядки своего аккумулятора.

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Преимущества и недостатки беспроводного варианта подзарядки

Если рассуждать логически, в сфере смартфонов никогда не задерживаются бесполезные технологии: они испытываются, терпят фиаско среди пользователей и убытки компании, затем отвергаются. Значит, беспроводная зарядка не бесполезна априори…

• + Возможность заряжать несколько устройств от одной зарядки

Надоело использовать зарядный кабель для каждого портативного устройства? Уже доступны беспроводные зарядные панели, которые могут вмещать более одного устройства одновременно.​

• + Водонепроницаемость

Индукционная катушка запечатывается внутри корпуса, вместе с тем есть возможность полностью обезопасить смартфон от воды, если убрать за ненадобностью гнездо проводной зарядки.

• + Безопасные точки зарядки

Эту технологию можно легко использовать для создания безопасных точек зарядки в общественных местах. Поскольку индуктивная зарядка стандартизирована, рестораны и кафе могут включать зарядные зоны в столешницы, а авиакомпании могут размещать зарядные устройства в подлокотниках.

• + Удобство отсутствия проводов

Гнезда для проводной зарядки могут расшатываться и выходить из строя, требуя в итоге ремонта. К тому же беспроводная зарядка куда удобнее в плане отсутствия проводов.

Какие недостатки?

• — Менее эффективно, нежели проводной метод

Существующие системы индуктивной зарядки не так эффективны, как зарядка с помощью кабеля: для полной зарядки телефона, заряжаемого на беспроводной зарядной площадке, требуется больше времени. Разница минимальная, но как факт.

• — Отсутствие универсального стандарта

Также не существует полностью стандартизированной системы индуктивной зарядки. Значит устройство, способное заряжаться по беспроводной сети, может быть несовместимо с зарядной панелью другого вашего гаджета. Тем не менее несколько крупных производителей начали работать в этом направлении (стандарт «Qi») – это LG Electronics, Motorola, Nokia, HTC, Sony и Samsung. Со временем проблема решится.

• — Меньшая «гибкость»

Это обратная сторона удобства без проводов, ведь смартфон должен находиться в одном положении, чтобы процесс зарядки не прерывался. А вот телефон, подключенный через кабель, можно брать и вертеть в руках как хочется.

Есть ли будущее у индуктивной зарядки?

Пока что беспроводная зарядка является лишь дополнительной функцией к проводной. Об этом свидетельствует и то, что сейчас производители работают над повышением скорости именно проводной зарядки, вкладывая финансы в исследования. Индуктивная зарядка пока что на стадии медленного развития и в ближайшие года не заменит проводной вариант.

В этом Telegram-канале по цене ниже рынка продают свои гаджеты популярные блогеры.

Источник: Lifewire.

Если вам интересны новости мира ИТ так же сильно, как нам, подписывайтесь на Telegram-канал. Там все материалы появляются максимально оперативно. Или, может быть, удобнее «Вконтакте»?

Читайте нас где удобно

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Для тех, кто долистал

Ай-ти шуточка бонусом. Старые модели сумок для ноутбуков отлично подходят к новым моделям смартфонов Samsung.

Узнать поддерживает ли телефон беспроводную зарядку можно только из технических характеристик, которые указал производитель. Сейчас технология обозначается как «индуктивная зарядка», «Qi-Power» или просто как «поддержка Qi», реже «Wireless Charger Support».

Помимо беспроводной («wireless») существует ещё и технология быстрой зарядки («quick charge»/«fast charge»/«speed charge») — не перепутайте. Смотрите полный список названий быстрой зарядки, их сравнение, плюсы и минусы.

Это руководство поможет самостоятельно разобраться и понять, есть ли в вашем мобильном устройстве возможность зарядки без проводов.

Обновлено в июне 2021: освежили инструкции, убрали бесполезную информацию, удалили «яндекс-маркет» (так как он оказался бесполезным в поиске), добавили список проверенных моделей и предложили, что можно сделать для тех, у кого нет технологии.

Как узнать, поддерживает ли смартфон беспроводную зарядку?

Просто посмотреть на телефон и понять, есть ли у него беспроводная зарядка — невозможно. Внешне она себя никак не проявляет. Нужно проверять её поддержку.

Нам часто задают вопрос, есть ли на таком-то телефоне/смартфоне поддержка беспроводной зарядки. Чтобы не ошибиться и верно ответить, мы смотрим документацию и характеристики по модели.

Вы можете самостоятельно найти свой аппарат в системах-агрегаторах для проверки. Остановимся на такой проверке подробнее.

3 сервиса для проверки поддержки беспроводной зарядки

Выясните название модели вашего мобильного устройства. Используйте указанные ниже сервисы, чтобы проверить смартфон, есть ли у него беспроводная зарядка.

С помощью сервисов также легко отсортировать модели по присутствии в них такой технологии, чтобы не купить те, в которых её не окажется (а вам бы очень хотелось, например).

1. Введите название на сайте WPC

Начните с официального сайта WPC (Wireless Power Consortium — Консорциума беспроводной электромагнитной энергии). Консорциуму принадлежит разработка самого протокола Qi (все подробности можете узнать на Wikipedia). Считается, что каждый производитель зарядного устройства Qi-типа (а значит и смартфонов, планшетов) должен регистрироваться в этой базе.

Если в таблице пусто и ничего не получается найти, то не спешите расстраиваться — нужно проверить в нижеследующих сервисах. Дело в том, что консорциум WPC почему-то выводит не всю информацию (в основном только модели последних трёх лет).

2. Проверьте в списках GSM Arena

На сайте GSM Arena беспроводная зарядка обозначена даже для тех смартфонов, которые ещё и не вышли (в разработке). Это удобно, если вы ожидаете определённую модель и хотите удостовериться, что в ней есть эта технология. Однако могут возникнуть проблемы или неточности с проверкой редких моделей (например, российских или китайских).

В каталоге встречаются ошибки. Например, в Xiaomi Mi Mix 3 (2018) есть беспроводная зарядка, а в Mi Mix 3 5G (2019) её нет, хотя на сайте показывается, что есть. Если вам нужна более точная информация, то проверьте в дополнительных источниках ниже.

3. Используйте каталог Kimovil

Честно говоря, база данных сайта Kimovil нам очень импонирует — она весьма точна и уже много лет выручает при поиске характеристик и ориентировочных цен на различные даже редкие модели смартфонов. Сервис отслеживает наличие беспроводной зарядки и других технологий, мониторит цены и следит за эффективностью вложений денег (по своим алгоритмам), но иногда недоступен из России (случайно попадает под блокировку пула IP-адресов Роскомнадзора).

Если ни в списках, ни в описании конкретной модели по каталогу Kimovil вы не нашли своего устройства, а также проверили предыдущие два пункта, то с высокой долей вероятности поддержки беспроводной зарядки нет.

Есть ли возможность сделать беспроводную зарядку на устройстве, которое её не поддерживает?

Да, такая возможность есть. В интернете можно найти по запросу «ресивер беспроводной зарядки» в продаже фабрично изготовленную приёмную Qi-катушку, выполненную в форме вкладыша. Её достаточно подключить к зарядному USB-порту на смартфоне и подложить под чехол.

Это может быть неудобно в некоторых случаях. Например, без чехла идея вовсе бесполезна, так как ресивер будет мешаться. К тому же разъём всегда теперь занят.

Примеры вкладышей беспроводной зарядки на Aliexpress:

• • Брендовый Qi-ресивер Uverbon с разъёмом Type-C (от 250 рублей, более 1000 заказов);
• • Qi-ресивер универсальный с разъёмами iPhone, microUSB (тип A и B), USB Type-C (от 120 рублей, более 2000 заказов).

В комплекте «зарядник + ресивер» покупать не рекомендуем, так как обычно в них низкокачественные изделия. Читайте дополненные отзывы перед покупкой (подробнее, почему на Aliexpress отзывы полны разочарования).

***

Недорогие смартфоны чаще всего не имеют поддержки беспроводной зарядки. Это недешёвая технология. Она занимает место под крышкой и требует тщательной проверки системы охлаждения.

Если в смартфоне есть быстрая зарядка или NFC-модуль, то это совсем не значит, что будет и беспроводная зарядка (некоторым пользователям почему-то кажется, что это как-то влияет).

Производителям просто невыгодно оснащать устройство дополнительной катушкой. Ведь главная задача бюджетной модели — предложить покупателю максимально низкую цену на фоне конкурентов.