On October 19, Xiaomi officially announced that it has broken through 80 watts of wireless charging technology. This is coming only two months after its world-class high-end flagship phone release “the Xiaomi Mi 10 Extreme Commemorative Edition“ mobile phone with 50 watts of wireless charging technology. Among other things, do we have other devices that can benefit from wireless fast charging apart from mobile phones?
Major Players in The Mobile Phone Fast Wireless Charging Technology Field
According to official sources, using Xiaomi’s 80-watt wireless second charge, a 4000mAh battery can be charged to 50% in 8 minutes and fully charged in 19 minutes, which is very close to the fastest wired fast charge on the market.
Since the development of smartphones, both consumers and manufacturers have felt little innovation and few transformative subversions, and wireless charging is definitely one of them.
For a long time, Chinese phone manufacturers have been at the forefront of this technology, and there are many investors.
For example, OPPO recently revealed a 65-watt wireless charging solution that is said to be able to fully charge a 4000mAh battery in 30 minutes.
In addition, the OnePlus 8 Pro also comes with an optional 30-watt wireless charger.
Xiaomi has been exploring wireless charging technology for more than two years. From March 2018, Xiaomi’s domestic debut of 7.5-watt wireless charging, to 20 watts in February 2019, 30 watts in September 2019, 40 watts in March this year, and 50 watts in August, the progress has been rapid.
Equipment/Devices That Can Benefit From Wireless Fast Charging Apart From Phones
In fact, smartphone charging is only a drop in the application of wireless power transmission, and it is only known for being close to the lives of the people.
Also, in the fields of automobiles, industrial manufacturing, and even space exploration, the demand for wireless power transmission is increasing day by day. Suffice to say, once this technology is popular on a large scale, it will inevitably reshape the way that human society uses energy.
Wireless Power Supply and Transmission Technology
Wireless power transfer (WPT) or wireless energy transmission (WET) refers to the transmission of electrical energy without wires as a physical link.
In the wireless power transmission system, the transmitting device generates a time-varying electromagnetic field driven by the power of the power source and transmits the power across space to the receiving device. The receiving device extracts power from the electromagnetic field and supplies it to the electrical load.
Types of Wireless Power Transmission Technology
Wireless power transmission technologies are mainly divided into two types: near field and far-field.
1. Near-Field(Non-Radiation) Technology
In the near-field (non-radiation) technology, by using the magnetic field of inductive coupling between wire coils, or by using the electric field of capacitive coupling between metal electrodes, the transmission of electricity in a short distance is realized.
Inductive coupling is currently the most widely used wireless technology. Its applications include wireless charging for mobile devices such as mobile phones and implantable medical devices, RFID tags, induction cookers, and electric vehicles.
2. Concept of Far-Filed(Radiation) Technology
In the far-field (radiation) technology, energy is transmitted by electromagnetic radiation beams, such as microwaves or laser beams, so it is also called a power beam.
Far-field power transmission technology can transmit energy to a greater distance, but it must be aimed at the receiver. Applications of this type of power transmission technology are solar satellites and wireless powered drones.
In the 19th century, the theory of how to transmit electrical energy has developed considerably. Faraday used his law of induction in 1831 to describe the electromotive force of a current in a conductor loop driven by a time-varying magnetic flux.
Many inventors and experimenters have observed electric energy transmission without wires, but due to the lack of a unified theory, people vaguely attribute these phenomena to electromagnetic induction. It was not confirmed until James Maxwell established a theory that unified electricity and magnetism into electromagnetics. The existence of electromagnetic waves as the “wireless” carrier of electromagnetic energy.
Nikola Tesla Contribution to Far-Field power Transmission
The first time that wireless power transmission made waves in history had to wait for the genius inventor Nikola Tesla. After 1890, Tesla used a spark-excited radio frequency resonant transformer (now called a Tesla coil) to transmit power through the inductive and capacitive coupling, generating a very high AC voltage.
Tesla earlier developed a wireless lighting system based on the near-field inductance and capacitive coupling and conducted a series of public demonstrations of wirelessly lighting incandescent bulbs. Although he failed to make his findings into commercial products in the end, Tesla’s resonant inductive coupling method has now been widely used in short-distance wireless power transmission systems.
In terms of far-field power transmission, Tesla is trying to develop a wireless power distribution system. He hopes to transmit power directly to homes and factories over long distances. In 1900, Tesla proposed a “World Wireless System” to transmit information and electricity around the world. In 1901, he tried to build a large high-voltage wireless power station in New York, now called the Wardenclyffe Tower, but by 1904, the investment dried up and the facility was never completed.
Electric Vehicles and Near Field Charging Technology
Inductive energy transmission between coils is the earliest wireless charging technology developed. It has been in existed since the development of transformers in the 19th century.
In the early 1960s, resonant inductive wireless energy transmission was successfully applied to implantable medical devices, including devices such as pacemakers and artificial hearts.
In recent decades, the proliferation of portable wireless communication devices such as mobile phones, tablets, and notebook computers is currently driving the development of mid-range wireless power transmission and charging technologies.
In 2008, the Wireless Power Consortium (WPC) was established. Its Qi inductive power supply standard released in August 2009 can efficiently charge and transmit power to portable devices up to 5 watts within a distance of 4 cm.
But looking forward to the future, in addition to mobile phones and various household smart devices, electric vehicles will also become one of the largest use scenarios for near-field charging, which will drive the development of related industries.
Take Northern Europe, where the fuel vehicle ban is more pronounced, as an example, Norway has formulated the ambitious ElectriCity plan. This plan requires all taxis to achieve zero exhaust emissions by 2024, and even gasoline-electric hybrid vehicles are also banned.
Now, 50% of new cars in Norway are electric vehicles, far higher than the proportion of any country. The Norwegian government has issued a decree that all new cars must achieve zero emissions by 2025.
This carrot-and-stick urgency has prompted a partnership between Jaguar, wireless charging company Momentum Dynamics, Nordic taxi operator Cabonline, and Fortum Recharge. The group’s goal is to build the world’s first wireless charging taxi fleet.
To this end, Jaguar will equip 25 I-Pace SUVs with Momentum Dynamic inductive charging pads. These mats are about 60 cm square and have a power rating of 50 to 75 kilowatts. When a car is driving in a taxi queue, the Jaguar will stop on a series of induction coils embedded in the road. Using 85 Hz resonant magnetic coupling, the charging board will deliver enough power to the taxi’s battery, and wireless power transmission can increase the cruising range by about 80 kilometers every 15 minutes.
Since 2015, Momentum Dynamic has been conducting electric bus trials in four cities in the United States to prove its wireless charging concept. In these bus trials, a bus in Washington State was charged at a speed of 200 kilowatts from charging boards installed along the way. Momentum Dynamics CEO Andrew Daga said, “This speed is already on par with some of the fastest DC chargers, enough to keep buses running 24 hours a day.”
In addition, Daga claims that its technology can provide a charging efficiency of 94%. When the scalable power rises to 200 or even 350 kilowatts, the charging efficiency remains stable. Momentum executives said they have reached an agreement with an unnamed European manufacturer to produce a wireless charging city delivery truck.
In China, Momentum Dynamic cooperates with Geely, a Chinese electric car company. In terms of specific details, the high-power wireless charging technology and automatic parking technology jointly developed by Momentum Dynamics and Geely’s China-Europe Automotive Technology Center (CEVT) were formally showcased in the first half of this year.
The test vehicle is equipped with CEVT’s latest sensor-based automatic parking system, which can realize real-time calibration feedback with the charging pad provided by Momentum Dynamics.
CEVT also said that by combining the real-time calibration feedback of the automatic parking system with wireless charging technology, the vehicle can complete the charging operation by itself. During the test, the parking position of the vehicle is basically within the calibration tolerance range, and no human intervention is required. Momentum Dynamics also revealed that in the next phase, both parties will work to apply the technology to different types of vehicles and scenarios to ensure that users can wirelessly charge anytime, anywhere.
Wireless Power Transmission Technology is Approaching Reality
It can be said that there will be wireless power transmission technology in any sci-fi scene, and now, this imagination is getting closer and closer to reality.
Before World War II, there was little progress in wireless power transmission. Mainly because the radio was developed for communication purposes, and relatively low-frequency radio waves propagate in all directions, and very little energy reaches the receiver, so they cannot be used for power transmission.
However, the development of microwave technology during World War II made far-field power transmission possible for the first time. In the 1960s, American electrical engineer William C. Brown (William C. Brown) first realized long-distance wireless power transmission.
One of the main motivations for microwave research in the 1970s and 1980s was the development of solar-powered satellites. The idea was proposed by Peter Glaser in 1968. It plans to use solar cells to collect energy from sunlight and transmit it to the huge power grid on the earth in the form of microwaves.
In 1975, Brown conducted a landmark experiment in which he demonstrated long-distance power transmission. He transmitted 475W of microwave power to a rectangular antenna one mile away, and the conversion efficiency of microwave to DC reached 54%.
In recent years, Emrod, a New Zealand start-up company, has been developing a safe and wireless way to transmit electricity over long distances and has implemented it in cooperation with the country’s second-largest electricity distributor.
Soon, the world’s first commercial long-distance wireless power transmission system will be piloted.
Emrod’s system uses a transmitting antenna, a series of relays, and a receiving rectenna (a rectenna that converts microwave energy into electrical energy). Emrod’s novelty is to draw on the concepts of radar and optics and focus the transmission radiation more closely than the previous microwave-based wireless transmission.
In addition, a safety feature of the Emrod system is a laser array spaced along the edge of the flat panel receiver, planned to capture and deliver along the focused energy beam. These lasers are pointed at the sensors of the transmitter array so that if a flying bird interrupts one of the lasers, the transmitter will pause a portion of the energy beam just enough for the bird to fly over.
Emrod said that it can work under any atmospheric conditions, including rain, fog, and dust. The transmission distance is only limited by the line of sight between each repeater, making it possible to transmit electricity for thousands of kilometers. Infrastructure costs, maintenance costs, and wired solutions have minimal impact on the environment.
In fact, Emrod believes that wireless transmission is a key technology for renewable energy power generation. This is because renewable energy power generation is usually carried out far away from need. This kind of system can well send offshore and remote renewable energy power generation products into the urban power grid without the need for giant batteries.