Wireless charging technology

Wireless charging technology originates from wireless power transmission technology, and its principle is to transmit energy between the charger and the electric device with a magnetic field.

It can be divided into two types: low-power wireless charging and high-power wireless charging. [1] Low-power wireless charging often adopts electromagnetic induction; high-power wireless charging often adopts resonance, and the power supply equipment transmits energy to the electrical device

The research team of the Massachusetts Institute of Technology published their research results on the website of the American "Science" magazine on June 7, 2007. The research team applied resonance to the transmission of electromagnetic waves and successfully "caught" electromagnetic waves. They used copper coils as electromagnetic resonators, with one coil attached to the transmitter and the other to the receiver. When the transmitter sends out electromagnetic waves of a specific frequency, the electromagnetic field diffuses to the receiver, and the power is wirelessly transmitted. The technology, which they call "wireless power", has been tested several times and has successfully powered a 60-watt light bulb two meters away. The furthest power transmission distance of this technology can only reach 2.7 meters, but the researchers believe that the power source can already charge the battery within this range. And only one power supply needs to be installed to power the electrical appliances in the whole house.

2 principle editing

Electromagnetic induction charging

The alternating current of a certain frequency in the primary coil generates a certain current in the secondary coil through electromagnetic induction, thereby transferring energy from the transmitting end to the receiving end. At present, the most common charging pad solution uses electromagnetic induction. In fact, there is not much mystery in the technical realization of the electromagnetic induction solution. China's local BYD company applied for the non-contact induction method as early as December 2005. The charger patent uses electromagnetic induction technology.

magnetic resonance charging

It consists of an energy sending device and an energy receiving device. When the two devices are adjusted to the same frequency, or resonate at a specific frequency, they can exchange energy with each other. It is a technology currently being researched by the Massachusetts Institute of Technology. A research team led by Marin Soljacic, a professor of physics at the Institute of Technology (MIT), used the technology to light a 60-watt light bulb two meters away, and named it WiTricity. The diameter of the coil used in this experiment reaches 50cm, which cannot be commercialized yet. If the size of the coil is to be reduced, the received power will naturally decrease

wireless charging

This is a relatively mature technology, similar to the ore radios used in the early days. It is mainly composed of a microwave transmitter and a microwave receiver, which can capture the radio wave energy bouncing off the wall and maintain a stable DC while making adjustments with the load. Voltage. This method requires only a transmitter mounted on a wall plug, and a "mosquito" receiver that can be mounted on any low voltage product.

3.Mainstream technology

So far, there are three mainstream wireless charging standards: Qi standard, Power Matters Alliance (PMA) standard, Alliance for Wireless Power (A4WP) standard, and iNPOFi technology. Below we briefly introduce these four standards.

1. Qi standard

Qi is the world's first standardization organization to promote wireless charging technology - the "wireless charging" standard launched by the Wireless Power Consortium (WPC), which has two characteristics of convenience and versatility. First of all, products of different brands can be charged with Qi wireless chargers as long as they have a Qi logo. Secondly, it overcomes the technical bottleneck of "universality" of wireless charging. In the near future, mobile phones, cameras, computers and other products can be charged with Qi wireless chargers, making it possible for large-scale applications of wireless charging.

The mainstream wireless charging technology in the market mainly uses three methods, namely electromagnetic induction, radio waves, and resonance, and Qi uses the most mainstream electromagnetic induction technology at present. In terms of technology application, Chinese companies are already at the forefront of the wireless charging industry. It is reported that Qi's application products in China are mainly mobile phones. This is the first stage, and it will be developed and applied to different types of digital products with higher power in the future.

2. Power Matters Alliance standard

The Power Matters Alliance standard was initiated by Duracell Powermat, which is a joint venture between Procter & Gamble and wireless charging technology company Powermat, and has relatively excellent comprehensive strength. In addition, Powermat is also one of the supporting members of the Alliance for Wireless Power (A4WP) standard.

Three companies, AT&T, Google and Starbucks, have already joined the PMA Alliance (Power Matters Alliance abbreviation). The PMA Alliance is committed to creating a wireless power supply standard for mobile phones and electronic devices that meet IEEE standards, and has a leading position in the field of wireless charging.

Duracell Powermat has launched a WiCC charging card that uses the Power Matters Alliance standard. WiCC is a circle larger than SD card, embedded with components such as coils and electrodes for electromagnetic induction non-contact charging. The thickness of the card is relatively thin. The terminal easily supports contactless charging.

3. A4WP standard

A4WP is the abbreviation of the Alliance for Wireless Power standard, which was created by the wireless charging alliance jointly created by Qualcomm, Samsung, and the aforementioned Powermat. The alliance, which also includes members such as Ever Win Industries, Gill Industries, Peiker Acustic and SK Telecom, aims to establish technical standards and industry dialogue mechanisms for wireless charging equipment for electronic

4. iNPOFi technology

iNPOFi ("invisible power field", that is, "invisible energy field") wireless charging is a new wireless charging technology. Its wireless charging series products adopt intelligent electric transmission wireless charging technology, which has the characteristics of no radiation, high power conversion efficiency, and weak thermal effect.

Compared with other existing wireless charging technologies, iNPOFi intelligent non-radiation technology, iNPOFi has no radiation, adopts the electric field pulse mode, and does not generate any radiation. The test results of China Tell Laboratory show that the added value of radiation is almost zero. In terms of high efficiency, Thiel's laboratory also determined that the charging transmission efficiency of products with this technology is as high as 90%, completely changing the low efficiency of traditional wireless charging up to 70%. In terms of intelligent management, chip adaptation management technology is adopted, including: automatically turning on and off the charging process; automatically adapting the required voltage and current, and managing the charging process to ensure high charging efficiency; and can use a unified charging It can charge any brand and model of electronic products safely, conveniently and efficiently. In terms of safety, various safety issues in weak current charging have been considered, such as electrostatic ESD protection, anti-overcharge, anti-shock, etc., and even if there is a problem with the power management of the powered device itself, it can be automatically fused through the inpofi chip Protect electronic equipment from damage. It is worth mentioning that for smart device manufacturers, inpofi uses an extremely small chip as the core to achieve ultra-micro design, only 1/4 the size of a fifty cents coin, and can be easily integrated into any device. It can also be integrated into various forms of wearable devices. This is beyond the reach of products based on traditional electromagnetic principles.

As a new generation of wireless charging technology standard, iNPOFi technology is efficient, green, convenient and economical. The charging equipment using this technology includes two parts: a power transmitting device and a power receiving device. The size and thickness of the transmitting device are comparable to ordinary mobile phones. The receiving device is embedded in the protective case of the mobile phone. Put the mobile phone in the protective case and place it flat on the transmitting device for charging. . During the charging process, the mobile phone does not need to be plugged in with any cables. Relevant tests show that the electromagnetic radiation is zero during the charging process, and the power conversion efficiency reaches 94.7%, which is close to wired charging. The charging device supports low-voltage power supply and is compatible with ordinary USB power supply; realizes low-temperature charging, effectively ensuring the safety and life of the device and battery.

products, including portable electronic products and electric vehicles.

ChangZhou Elec IMP&EXP CO.,LTD.

Dec 11^th , 2022