What happened to wireless charging technology?

Recently, the technical director of a local company said, "The mainstream wireless charging research in the world is developing in the direction of high power and long distance, and may achieve great success in 20 years. But my focus is on how to use this technology to reduce the use of disposable batteries and reduce the types and number of chargers. The direction is slightly different. But I firmly believe that my direction will benefit mankind in the short term." He believes that the current development direction of these international manufacturers in the field of wireless charging is wrong. So what is the company's wireless charging technology idea?

　　We live in a world surrounded by cables, but this is too troublesome, not only affecting the appearance but also being environmentally unfriendly. Wiring requires a lot of copper, plastic, and manpower, and you always have to reserve space for cables when you are doing home decoration or architectural design. Therefore, we have been looking for an effective, safe, and wireless power transmission device, and one of the byproducts is the microwave oven.

　　Wireless charging technology shows great potential in the consumer market. Charging electronic devices without the use of wires not only provides a convenient solution for portable device users, but also allows designers to find more innovative problem-solving methods. Many battery-powered portable devices can benefit from this technology, ranging from mobile phones to electric vehicles.

　　Scientists and engineers have known for nearly two centuries that transmitting electricity does not require wires to be in physical contact at all times. Electric motors and power transformers contain coils of wire that transfer energy to each other through a phenomenon called electromagnetic induction. Current in a transmitting coil can induce a current in another receiving coil through electromagnetic induction; the two coils are close together but not touching. But scientists have also discovered that radio waves carry electromagnetic radiation, but transferring energy from one point to another through traditional electromagnetic radiation is very inefficient because electromagnetic waves usually spread out in all directions and most of the energy is lost during the propagation process. It can also be dangerous, especially when the level of electromagnetic radiation exceeds the range that the human body can withstand.

Current status of wireless power supply technology　

　　At present, there are three main types of wireless power transmission technologies: electromagnetic induction (using current through coils to generate magnetic force to achieve short-range wireless power supply), radio wave reception (converting power into radio waves for short-range wireless power supply), and magnetic field resonance (using magnetic field and other resonance effects for short-range wireless power supply). The development direction of the above technologies has always focused on the improvement of power transmitters and receivers. The direction of radio wave reception technology is mainly to improve the Q value of current and maintain transmission efficiency, which is not very meaningful for low-power consumer electronic products. Compared with magnetic resonance and electromagnetic induction technology, it has more commercial promotion value.

　　In June 2007, the Massachusetts Institute of Technology (MIT) and in August 2008, Intel Corporation respectively published technologies using magnetic field coupling resonance, which are expected to charge cars while driving, although the transmission efficiency is only about 40%. Based on magnetic field coupling resonance technology, Sony Corporation of Japan has developed a technology called "Repeater Device" to extend the wireless transmission distance. This technology can transmit 60W of power to a TV set as far as 50cm away without a power cord. The related technology was also used by Haier of China to showcase its "tailless TV" at the CES exhibition held in the United States in 2010.

　　Inductive coupling is another efficient and universal wireless charging method, which mainly sets electrodes in the power supply part and the receiving part respectively, and uses the electric field generated between the electrodes to supply power. Since there is a capacitive coupling effect between the electrodes, the electric field coupling method is also called the capacitive coupling method. At the Shenzhen High-Tech Fair Electronics Exhibition held last year, Murata exhibited an electric field coupling wireless power transmission module that supports mobile device charging. The "wireless charging" function can be achieved by integrating the RFIC into the mobile device and the charging plate with the charging module implanted.

A new type of resonance-based non-contact charging has also been unveiled. This is a technology that uses electric field coupling resonance that Takenaka Komu is developing. Although this technology requires the power transmission end and the power receiving end to be in close contact, it supports horizontal displacement and does not cause problems such as heating, electromagnetic waves, and high-frequency waves when foreign objects invade, as is the case with the currently practical electromagnetic induction-based non-contact charging technology that supplies power from coil to coil. In addition, unlike the electromagnetic induction method, the resonance method does not use ferrite and Litz coils, so the weight and cost of the product can be reduced.

　　In addition, Sony's TX300V/TX200V compact camera and Sharp's SH-13C mobile phone all use wireless charging. The SH-13C takes about 2 to 2.5 hours to fully charge the 1230mAh battery in the phone. Qualcomm has developed an "eZone" that uses magnetic resonance for wireless power supply, which can charge the "iPhone" with a charging stand. According to tests, if a 1000mAh battery is charged, it can be fully charged within 2 hours.

　　In addition to these international manufacturers, there are also many related products in China. Open Taobao and search for "wireless charger", you can see hundreds of wireless charging plates or mobile phone cases for iPhone, with prices ranging from more than 100 yuan to more than 900 yuan. This kind of product (similar products such as "Philosopher's Stone") is generally divided into two parts: one part is the charging plate, and the other part is the power receiver connected to the mobile phone. Its implementation principle is still electromagnetic induction, but there are also many problems. On the one hand, these Taobao products have problems with high heat generation and electromagnetic radiation; on the other hand, there is no ID authentication method for incorrect charging, which is easy to cause danger. At the same time, it is impossible to access the Internet and other data transmission while charging. In addition, the charging requirements are different for different batteries.

Establishment of WPC standards　

　　In order to solve the above problems, the Wireless Power Consortium (WPC), an industry standard organization specifically for wireless power, was established. The organization was founded in 2008 and is composed of companies from various industries in Asia, Europe and the United States, including electronic equipment manufacturers and original equipment manufacturers (OEMs). The WPC standard defines the type of inductive coupling (coil structure) and the communication protocol used by low-power wireless devices. Any device that works under this standard can be paired with any other WPC-compatible device. Products certified by the WPC Alliance will be marked with the "Qi" LOGO, and terminals with "Qi" can be charged on all charging pads marked with the LOGO. In addition, after obtaining the Qi logo, there is no need to pay the WPC Alliance.