Picture source @Visual China
Text | Gen New Future, Author | Chen Gen
The continuous leap in information technology has caused more and more electronic devices to appear in people's lives, and electronic devices everywhere have also brought the problem of charging at any time. Driven by demand, can meet the wireless charging at any time and be born with the trend.
In fact, more than 100 years ago, people imagined that they could search for power signals like we are now connecting to Wi-Fi signals, and then obtain power from a distance. Human efforts in this regard have always been stopped. Now, this idea of power acquisition across the air has become a reality and is increasingly used by people in life. Today, the world is gradually becoming a wireless world, and wireless charging technology has given people the flexibility they want to be more and more a cheap and reliable technology.
Tesla and wireless charging
In fact, wireless charging is not a technology that has only been available recently. As early as 1890, Serbian-American physicist and electrical engineer Nikola Tesla proposed the concept of wireless transmission , invented the " Tesla coil ", opening the door to the era of wireless power transmission. The wireless charging process of
is actually not complicated. Simply put, it means that when the current flows through the coil, a magnetic field will be generated; and the coil close to the magnetic field will produce induction current , thereby realizing the wireless transmission of the current . It can be said that there is a potential possibility for wireless transmission anywhere using electricity, but it was difficult to achieve in the past due to the low conversion efficiency and high cost.
is based on the concept of wireless transmission. In 1891, with the support of J.P. Morgan , Tesla began to test wireless transmission technology. Through the principle of magnetic induction coupled , it successfully lit a light bulb with wireless transmission, and built a large high-voltage coil in Long Island , New York - Worden Cliff Tower , also known as Tesla Tower. Teslata's goal is to build a prototype of a global transmission system, but later, Teslata's project was forced to stop due to funding issues. The real substantial progress in
wireless transmission technology was after the 21st century. Due to the leapfrog progress made in wireless communication application field, put forward an urgent need for practical application for transmission and charging technology, which also promoted major breakthroughs in wireless transmission technology and applications.
June 2007 , a wireless charging device piloted by a research team led by Massachusetts Institute of Technology Marin Soljahik can light up a 60-watt light bulb 7 feet (about 2.1 meters) away. At that time, this research result attracted great attention in the field of wireless power transmission.
After 2010, wireless power transmission technology has entered the substantive application stage, and has made substantial progress in the application fields of consumer electronics, electric vehicles, , smart home, smart wearables and other applications.
For example, in April 2014, the Cota technology of Ossia in the United States made a new breakthrough, which can achieve full-direction charging of smartphones from 12 meters away. In November 2014, the charging distance of WiTricity's magnetic resonance technology reached 2.4 meters, which can charge multiple devices at a long distance at the same time. In November 2015, Energous, a company in the United States, published a concept sample of RF to DC rectifier IC, which supplies power to small wearable devices and IoT devices, and can support wireless charging at a distance of 10 watts and 4.57 meters. In March 2016, the University of Washington developed the "Passive Wi-Fi" technology, which can be connected to Wi-Fi devices 30 meters away. This technology was also rated as the "Top Ten Technological Breakthroughs in 2016" by the "MIT Technology Review".
In April 2016, the Tesla wireless charging device "Plug-free Charging System" was launched. The device can be used in all Tesla brand models. The charging efficiency is equivalent to a 7.2-kilowatt secondary coil charging pile, which can support an electric vehicle's range of 20 miles (about 32 kilometers) per hour of charging.
In 2017, Apple realized wireless charging of mobile phones. It is worth mentioning that the strongest driving force for the development of wireless transmission technology comes from the fields of portable communication products such as smartphones, iPad, MP3, digital cameras and laptops.Although Apple's wireless charging is not a remote power transmission, under the commercialization of wireless charging, it has also brought mobile phone charging into a new chapter. Nowadays, wireless charging of mobile phones has become common in our lives, and wired charging of mobile phones is being replaced by wireless charging.
In addition, in 2019, Tesla launched a car accessories product that specializes in charging mobile phones. The device can be embedded directly below the central control screen of Model 3. After powering on through the USB interface, it can charge both mobile phones wirelessly at the same time. In January 2021, Xiaomi released air charging technology, which can realize the charging of devices within a long distance of 5 watts within a radius of several meters, and can support multiple mobile phones to use at the same time. In addition to mobile phones, wireless charging piles also support the charging needs of smart watches, , bracelets and other devices.
Is it still far from wireless charging of a car?
If wireless charging has an impact on mobile phones, computers, cameras and other electronic products, it has changed the flexibility of charging electronic products and brought more convenience to people, , then, wireless charging is the electric car industry, is a new shock, even , , is , , is a new shock, or even starts electric car key to the entire market - electric car wireless charging has no exposed connectors, which not only completely avoids safety hazards such as leakage and power disconnection, uses wireless charging, also can hide power and transformers underground, allowing the car to charge at special charging points on the street.
Currently, "mileage anxiety" is still a pain point that electric vehicles have not solved. Especially when the range of electric car owners shrinks in winter or when they need to travel far, the "mileage anxiety" of electric car owners will become more serious. Discussions such as charging queues in high-speed service areas during holidays and getting up at 4 a.m. to grab charging piles, etc. are also controversial on the Internet. This kind of anxiety is like we are always afraid that our mobile phones will run out of power, but it is different from the battery anxiety of mobile phones. If we have chargers at home and institution, there are power banks in our bags, and there are shared power banks in nearby shopping malls and restaurants, our battery anxiety about mobile phones will weaken or even disappear . For electric cars, car owners' anxiety is so common because car replenishment is not as convenient as charging on mobile phones.
However, if wireless charging of electric vehicles can be achieved on the road, the mileage anxiety that has always plagued the development of electric vehicles may be solved. Among them, the most typical solution is to install an electric energy transmitting device on the road surface and the vehicle chassis is equipped with a receiver. In this way, when the vehicle is driven to the corresponding road surface, it can receive the electromagnetic waves emitted by the transmitting device and complete the charging. According to this principle, if such an electric energy transmitting device is laid on all highways or urban main roads, the vehicle can complete charging while traveling.
Many electric car manufacturers are also actively exploring the possibility of commercial use of this technology. BYD applied for the non-contact induction charger patent as early as December 2005. In July 2012, BYD successfully sold University of Utah a pure electric bus, which is equipped with the latest wireless charging pad. This was developed by a leader in the Energy Dynamics Laboratory of Utah State University. The driver parked the bus on the charging pad and was fully charged after several minutes of waiting.
Two companies that study the next generation of wireless charging technology, WiTricity and Fulton Technology have also won many mainstream electric manufacturer partners . Among them, WiTricity was established in 2007 and is committed to commercializing wireless charging technology. WiTricity has developed an electric car charger that can charge across the air. It is a half-meter-wide board placed on the ground of the garage. The car can be charged by driving it up.
At present, WiTricity has signed a multi-million-worth contract with Toyota to develop battery-powered car chargers, and announced a partnership with Mediatek, a Taiwanese electronics manufacturer, to develop products that charge mobile devices.
Another startup, Fulton Technology, said it can penetrate several centimeters of thick marble or garage floor to wirelessly charge electric vehicles. These technologies are more practical than the existing induction charging – existing technologies allow you to wirelessly charge your car in your own garage, but you must park in a specific location and calibrate with the charging coil.
Fulton has been acquired by the American chip design company Qualcomm . Since the beginning of 2012, Qualcomm has jointly conducted commercial testing of street wireless charging in the East End of London in Renault and Delta Automobile. Qualcomm envisions building wireless charging facilities in shopping mall parking lots and public road parking points, using semi-dynamic charging, such as setting up charging points at traffic warning lights, intersections, taxi stops and bus stations. There is no need to be fully charged every time you charge, just keep 40% to 80% of the battery.
Germany, Japan and other countries are also very active. In Munich, Germany, has been testing for home wireless charging for a long time. Japan Toyohashi University of Technology is studying a road charging device that can transmit electricity to cars through 20 cm thick concrete bricks. At a trade show held by Yokohama , Toyohashi University of Technology and Science in Japan demonstrated their road wireless charging technology, through which vehicles can charge while walking. Researchers named this road charging device "Ever" (EVER), which is the English abbreviation of "Electric vehicles on live roads." They believe that the cost of "road charging" is lower than building a dedicated electric vehicle charging station.
A wireless world
At present, wireless charging is developing rapidly and showing two trends.
, on the one hand, is a reduction in wireless charging costs. Today, wireless charging modules account for nearly 15% of the total price of smartphones, and the costs of each link are expected to drop rapidly: the overall cost of a 5-watt wireless charging Qi standard single-mode device is around US$2.2, and the cost price of a single coil is already below US$0.8.
Although the cost of electric vehicle wireless charging module is still high - the initial construction cost of wireless charging stop points is 4 to 5 times that of wired electric piles; the cost of installing wireless charging modules for electric cars is more than 15,000 yuan, while the cost of commercial vehicles is as high as 100,000 yuan, compared with wired charging stations, wireless charging stop points have the advantages of low maintenance costs, safety and high space utilization.
On the other hand, the conversion efficiency of wireless charging is rapidly improving . At present, the efficiency of wired charging is about 93%, while the efficiency of wireless charging devices is between 75% and 90%; the charging distance, angle, and ambient temperature will all affect the conversion efficiency. In 2014, Qualcomm launched wireless charging technology with basic electromagnetic resonance, achieving a charging efficiency of 90%; Israel Powermat said that its contactless charging system's power transmission efficiency can reach 93%. Professor Kenji Ito, Japan, has integrated the antenna that converts microwaves into DC current and rectifier circuit , increasing the conversion efficiency of microwave wireless power supply technology to 93%. With the reduction of wireless charging costs and improved conversion efficiency, wireless charging has also shown its huge market potential. According to a report by research firm Knowledge Sourcing Intelligence, the global wireless transmission market is expected to grow at an average annual rate of 15.56%, from US$9.246 billion in 2019 to US$22.017 billion in 2025.
can be foreseen that from wireless charging of electronic products to wireless charging of electric vehicles, wireless charging in the digital society will also affect our lives in more aspects.
For example, in terms of smart homes, just imagine if the home is covered with spider web-like wires, it will not only affect the beauty, but also hide safety hazards. In the context of , wireless charging will be a key element in solving smart homes, and "tailless" devices will become the mainstream of home smart devices. At present, the US Powercast company has developed a receiving device that can convert radio waves into DC , which can power multiple electronic devices within a distance of nearly 1 meter.
In addition, medical device power supply is another important area of wireless power transmission. , for example, charging medical devices implanted into the human body such as pacemaker , muscle stimulation to people with lower limb paralysis, as well as medical stimulation, analgesia, etc. of nervous system , etc. Wireless charging of medical devices is mainly through ICPT (Inductively coupled Power Transfer) and RFPT (Radio Frequency Power Transmission) methods. First, a coil is set outside the human body, and secondly, a corresponding small and micro coil is implanted in the human body, forming an inductive coupling effect between the two to realize power transmission.
Overall, Now, wireless transmission technology has been put into practical applications in certain fields. , and, in the future, with the development of wireless charging technology, people will eventually usher in a wireless world: small electric toothbrushes, razors, pacemakers and smart cards, to electric transportation such as buses and trains, and even magnetic levitation trains will be powered through wireless charging. The arrival of the wireless charging world has given people the flexibility they want and opened a new chapter for the development of the digital world.
