How many people can't tell the difference between wireless charging and wireless power supply?

Wireless charging is very popular recently, and mobile phones are also using wireless charging technology on a large scale, but we are still far away from true wireless power supply (although the equipment of wireless power supply and wireless charging is similar, the concepts are still very different). However, recently wireless power supply has been first applied to the mouse.

Why is the wireless powered mouse used first? How far are we from true wireless power supply? This article will talk with you about wireless charging/power supply, as well as the difference between wireless charging and wireless power supply.

It all starts with wireless power transmission technology

In fact, whether it is wireless charging or wireless power supply, it actually originates from wireless power transmission technology.

When it comes to wireless power transmission, we generally believe that it was first invented by Nikola Tesla in the late 19th century. Tesla originally worked under Edison, but they broke up due to disagreements. The reason for the breakup was that Tesla believed that alternating current was the future, while Edison believed that the future belonged to direct current. They argued for a long time, and of course we all know the final result now.

One of the important reasons why alternating current is victorious is that it can be easily transformed. As we know, long-distance transmission of electrical energy requires ultra-high voltage to ensure that the loss of electrical energy is minimized during transmission.

If direct current needs to be transformed, it needs to go through the following steps: first, it needs to be converted into alternating current, then it needs to be transformed, and then it needs to be converted back into direct current. This will increase power loss, equipment costs, and processing difficulty. Therefore, alternating current has become the power transmission method we are currently using.

The wireless transmission of electric energy is based on the discovery and application of alternating current. A changing electric field can generate a changing magnetic field, which can stimulate a long-distance coil to generate a changing electric field (one of the working principles of a transformer). So many people at that time studied how to increase the distance, but unfortunately they never succeeded.

Four ways to transmit power wirelessly

Based on electromagnetic induction technology, the wireless charging/wireless power supply devices we are using now are all based on the principle of electromagnetic induction. At least the commercial devices we have now are all based on the principle of electromagnetic induction. There are currently four ways to achieve wireless power transmission: electromagnetic induction, electromagnetic resonance, electromagnetic coupling and microwave resonance.

Most of the wireless charging technologies we see today use electromagnetic induction technology. We can regard this technology as a separate transformer, in which the magnetic conductor (iron core) in the middle is removed.

The transmitting coil and the receiving coil are placed in two separate devices. When electric energy is input into the transmitting coil, a magnetic field is generated. The magnetic field induces the receiving coil and generates current. In this way, we have built a wireless power transmission system.

Because we have removed the magnetic conductor in the middle, the magnetic field weakens rapidly with the increase of distance, and the distance that electric energy can be transmitted is very short. Generally, it can only have a good transmission effect within the range of a few millimeters to a few centimeters. Therefore, it can only be used in small wireless charging devices with lower power.

Compared with electromagnetic induction, electromagnetic resonance is much farther in distance. Electromagnetic resonance requires the use of two coils with completely matched specifications. When one coil is energized, it generates a magnetic field, and the other coil resonates as a result. The current generated can light up a light bulb or supply power to a device.

Currently, the transmission range can reach several meters, but because it is a divergent transmission method, the overall efficiency is not high. However, the advantage is that it can transmit power to multiple devices at the same time and has a certain degree of freedom in horizontal position.

Electromagnetic coupling and microwave resonance are generally not favored. Electromagnetic coupling is limited in distance and its principle is similar to magnetic resonance, but it does not have many supporters. Microwave resonance currently has too low transmission power and its principle is similar to WiFi signal transmission (in fact, the transmission of wireless signals such as WiFi signals can also be considered a form of energy transmission, but because the energy is emitted in all directions, the utilization rate is extremely low).

The difference between wireless charging and wireless power supply

Well, now that we have understood the basics of wireless power transmission, let’s go back to our question: what is the difference between wireless charging and wireless power supply?

Both are essentially derived from wireless power transmission. As we all know, power transmission is the technology of transmitting electricity from the power generation device to the receiving end without cables. Because many people currently confuse wireless power transmission, wireless charging, and wireless power supply together, although the boundaries between the three are not very clear, there are still subtle differences.

From the perspective of our consumers, we can understand it simply as follows:

Wireless power transmission focuses on the word "input", which refers to the transmission of electricity. It is a process as well as a technology. Wireless power supply and wireless charging are two different ways of applying wireless power transmission technology.

Wireless charging is more about charging the energy storage and charging devices in the device. The key is that it is just a charging, and the object must carry an energy storage device or in layman's terms, a battery. At present, the significance and application scenarios of wireless charging are more in relatively fixed positions, and it is used to charge small battery devices.

Wireless power supply is a wireless power transmission device that transmits and distributes power to electrical appliances. The electrical appliances do not necessarily need to store power. Instead, it emphasizes immediate use (of course, it can also charge the battery) and provides power to electrical appliances that can be freely adjusted over long distances. The significance of wireless power supply is more about providing power to household appliances with higher power consumption, achieving the requirements of true wireless power consumption. It can be said that wireless power supply is more difficult than wireless charging, but it is also more meaningful.

Many people like to mix the three together and call them wireless charging. Indeed, in the current environment, we are more exposed to wireless charging. But in the future, with the development of technology, we still need to distinguish them in their respective application scenarios.

Why is wireless power first used on the mouse?

The first wireless powered mouse (note that it is powered) at present should be Razer's Mamba Ultra.

Logitech's G903 PowerPlay combination and Corsair's DARK CORE wireless charging mouse set both mainly charge internal batteries and are called wireless charging mice. The mouse battery is charged first, and then the mouse will use the power inside the battery. It does not directly use the power provided by the wireless charging mouse pad.

It is actually quite a good idea that wireless power supply was first used on the mouse. Firstly, the power consumption of the mouse is small and it does not require high-power wireless power transmission, so the current wireless power transmission technology can meet the power consumption requirements of the mouse.

Second, the mouse pad is a necessary item. Placing the mouse pad on the desktop as a necessary item for the mouse does not increase the extra space. Third, the power supply distance is short. The mouse is in close contact with the mouse pad during use. The maximum time you raise your hand is a few centimeters. The currently mature electromagnetic induction can fully meet this distance.

Low-power devices do not have to face the problem of heat dissipation. We have seen heat dissipation holes on many wireless charging devices. Some wireless charging devices even have internal air cooling. This problem will never occur on low-power products such as mice.

Summarize

In the future, wireless power supply will have a bigger stage in terminal devices. Not all load electrical appliances will be equipped with batteries, and it is not practical. High-power charging, such as electric vehicle charging, still uses wired charging. The use environment of wireless power supply will be much broader than wireless charging. Of course, the technical difficulty is also very high, but I believe there is a promising future.