Wireless power transfer uses radio to convert the power generated by the power plant into radio waves, and then collects and converts the radio waves into electric power through a specific receiving device for use people to use.

Wireless Power Transfer System

Catalog

I Introduction

Today, more and more electronic products bring great convenience to people's work and life, but most of the traditional power transfer methods are using through wires or sockets to transmit power to the terminal products. With the popularization of mobile devices, wireless data transfer, and wireless network technologies, people hope to get rid of the shackles of traditional power transfer methods and eliminate the troubles caused by chaotic power lines. As a result, wireless power transfer technology has become the most desirable technology in the 21st century, and wireless charging products have become a new focus among the public. At present, many countries around the world are researching and developing wireless power transfer technology, exploring the application of wireless power transfer systems in different fields, and striving to put it into practical use.

Wireless power transfer (WPT), also known as wireless energy transfer, is achieved by electromagnetic induction and energy conversion. wireless power transfer realizes non-contact power transfer mainly through electromagnetic induction, electromagnetic vibration, radio frequency, microwave, and laser. According to different wireless power transfer distances, wireless power transfer can be divided into three categories: short-range, medium-range and long-distance transfers.

II Development

(1) Tesla's most famous invention is the Tesla Coil, a distributed-parameter high-frequency resonant transformer that can obtain high-frequency voltages of millions of volts. Its circuit and principle are very simple, but it's not easy to adjust it to the perfect resonance with the environment. However, Tesla is the person who is especially good at this.

Tesla later invented the so-called "amplifier transmitter", now is called the high-power high-frequency transfer line resonance transformer, for wireless transfer test. It’s worth mentioning that Tesla uses the Earth as the inner conductor and the Earth's ionosphere as the outer conductor. Through this amplified transmitter’s unique radial electromagnetic-wave oscillation mode with the surface electromagnetic waves around the Earth, a low-frequency resonance of approximately 8 Hz is built between the Earth and the ionosphere.

Tesla Coil

This system is different from the energy emission mechanism of modern radio broadcasting, but similar to the relationship between the alternator and the transfer line in the AC power network. When there is no power receiving end, the transmitter only exchanges the reactive power with the heaven and earth resonant cavity, and there is very little power loss in the whole system. f it is a normal radio broadcast, the emitted energy is all lost in space.

Tesla has no financial resources to realize this idea in his lifetime, but the descendants have theoretically fully confirmed the feasibility of this scheme, which proves that this project is not only feasible, but also highly efficient, safe for ecosystem, and does not interfere with radio communication. However, considering its free access through the world, no one actually cares about this idea under the existing political and economic system.

(2) This technology is still in the research stage. As early as the first two years, scientists from all over the world began to study the use of wireless power transfer technology to build solar power plants on the moon and then transmit them back to the Earth to serve humans.

(3) Japan is also studying it intensively and plans to put it into use in residents' lives around 2015.

III Features

At the 2010 CES show, Haier launched a“no-tail" TV, which is based on wireless power transfer technology. If we transmit the current through the air, will the user get an electric shock? The researchers said that the wireless power transfer technology adopted by the “no-tail" TV does not generate radiation, and its security has been certified by FCC, IEEE and CCC standards. It does not cause danger, but also avoids security risks such as hot plugging, power line short circuit, etc. After ensuring its security, the wireless power supply method will completely solve the problems of messy wiring, fixed electrical location, socket ruining room decoration, etc., bringing more convenience and beauty to our lives.

More importantly, wireless power supply saves a lot of wires, whether it is rubber, plastic, copper, tin or other metals. Besides, it also saves resources and reduces pollution, which is low-carbon and environmentally friendly.

No-tail TV

IV Trend

According to the prediction of the Wireless Power Consortium, the global wireless charging market may reach $27 billion in output value by 2016. "Wireless charging technology"will be as popular as Bluetooth in the future." Industry insiders predict.

For consumers, the significance of wireless charging is not only the convenience for charging, but also the expansion of wireless charging technology from small power devices such as mobile phones and tablets PC to large-scale devices such as laptops, smart TVs and even electric vehicles. More surprises are worth looking forward to. 

The Truth About Wireless Charging

V Latest News

According to a report from the "Yomiuri Shimbun", a Japanese company announced on the 12th that a wireless power transfer technology test was successful completed. That means in the form of microwaves, the power can be transmitted to a place 500 meters away without using a cable.

In the experiment, 10 kilowatts of power was converted into microwaves transmitted to a panel-shaped receiving device 500 meters away through an antenna, and then the received microwaves were reverted to electric power, and finally illuminates the light-emitting diodes.

According to the report, the space is not affected by the weather, so solar power is 10 times more efficient than the power on Earth's surface. How to transfer solar power from the cosmic space 36,000 kilometers away to the ground is one of the keys to realize solar power generation in the universe. Mitsubishi plans to use the current transfer technology in power transfer project in the mountains in the next few years to achieve practical application as soon as possible.

VI Problems and Countermeasures

The main obstacles to wireless power transfer are the efficiency and distance, and the  diffusion, absorption and attenuation of airwaves are the difficulties of wireless transfer. In the process of transmitting energy in space, electromagnetic waves will be distributed in all directions, difficult to concentrate, and poorly oriented. Besides, air acts as a coupling medium, making the magnetic lines of the power carrier, especially microwaves,  be extremely depleted in space. Therefore, the wireless power transfer power is low and is poorly efficient, and it is difficult to transport a large amount of energy and perform high-power long-distance wireless transfer. For wireless charging, the charger and the device being charged are connected in the form of a magnetic field. Various kinds of interferences will cause loss of energy transfer. And the problem of small energy transfer and transfer range of the electromagnetic induction method also restricts the wireless charging development of electric vehicle.

Wireless power transfer project is huge, and two major problems of power production and transfer must be solved. In addition, for wireless charging products, wireless charging equipment must be certified by related organizations, and at the same time, the producers need to find a mature business model to open the market. In addition, the wireless charging technology needs to be improved, and an international standard is required to make the transceivers widely compatible.

Relation among Power&Voltage&Efficiency

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