The two most commonly used principles of wireless charging

- Sep 17, 2018-

    Wireless charging technology is no stranger to modern people, and many mobile phones already have it.The iPhone8/iPhoneX currently on the market supports wireless charging, but only at 7.5w and samsung has introduced a new wireless charging model that is said to be capable of charging up to 15w.However, there is a big gap between the current charging mode and the wired charging mode. We can only call it wireless slow charging, and according to users, this charging mode is easier to heat up.Not only in the mobile phone industry, electric cars are also a hot industry. Cars can realize wireless charging, and even many household appliances can realize wireless charging. That can bring great convenience to human beings.Therefore, in the field of wireless charging, the convenience brought to us is huge. We still need to work hard, and the popularization day is not far away.There are many ways of wireless charging. At present, we know that there are four ways: 1.2. Electromagnetic induction type;3. Magnetic field resonance type;4. Radio wave type.However, due to the low transmission power of the electric field coupling mode and radio wave, electromagnetic induction and magnetic resonance are commonly used at present.

First, electromagnetic induction charging technology

    The current passes through the coil, and the coil generates a magnetic field to generate an induced electromotive force to the nearby coil to generate a current. The conversion efficiency of the charging mode is high, but the transmission distance is as short as 0 mm to 10 cm, and the placement position is relatively high, and only The quasi-coils are performed one-to-one. Metal-induced contact also generates heat and causes heat. The wireless charging technology based on magnetic field induction is essentially the same as the hollow transformer. The principle is simple, the technology is mature, and the cost is low. It is a widely popular technology. However, the defect of the magnetic field sensing technology is that the transmission distance is short, and the degree of freedom in placing the charging device is low.

    The technology is not only applied to mobile phones, but has been applied in the field of electric vehicles. In today's automobile market, electric vehicles are no longer a niche market. With the support of national policies and the vigorous promotion of major manufacturers, the maintenance of electric vehicles The amount is constantly rising, this is a gratifying imagination. However, the problem has also followed. The lack of public electric piles and the long charging time have brought a lot of troubles to electric vehicle owners. In daily use, electric vehicles can not fully meet all the daily travel needs of people. The battery life problem restricts the distance of travel. If the mid-way car has no electricity, it can only be anxious. Even in a modern metropolis like Beijing, it is a luxury to find a utility electric pile at any time. Recently, some media reported that Oak Ridge National Laboratory made a major breakthrough in the field of wireless charging. A 20 kW wireless charging system has a charging efficiency of 90%, and the charging speed is three times that of the commonly used plug-in electric vehicle equipment. If this technology is widely used, it will promote the wireless charging of large-scale high-power cars, so that electric vehicles can be applied in more fields, and the fast and convenient charging mode will increase consumers' acceptance of electric vehicles.

    Magnetic resonance charging technology

    The rise of magnetic-resonance technology stems from an experiment at MIT in 2008, in which researchers turned on a 60W light bulb through the air, and for the first time made the world realize that wireless charging can still do this.Compared with magnetic induction technology, the advantage of magnetic resonance is that it can realize effective energy transfer in a larger range and achieve higher spatial freedom.Therefore, it is more reliable and supports multiple devices to charge at the same time.

    The sending end meets the receiving end with the same resonance frequency, and the power transmission is carried out by the resonance effect.This charging mode transfers a long distance, and at the same time, the transmitted power is relatively large, which is suitable for long-distance charging.However, this charging mode is less efficient, and there is a large loss in the transmission process. The farther the distance, the greater the transmission power, the greater the loss.More importantly, the frequency band must be protected from external factors.

    As far as the current technology is concerned, both charging modes have certain advantages and disadvantages. Generally speaking, they can only be charged in a fixed location and range, which is not convenient for mobile devices.So researchers are trying to develop ways to recharge power anytime, anywhere.

    Scientists in the United States have some bright ideas about how to apply wireless charging to highways.Under the asphalt layer of the highway, the primary coil is arranged at a certain distance, and the electric car can be charged as it passes above.Will make mobile wireless charging a reality and the road itself becomes a natural charging site.Imagine driving an electric car on a rechargeable highway and watching the battery charge slowly increase to reach your destination.Solving the fatal battery problem will be the biggest advantage of electric vehicles.