Analysis of domestic wireless charging chip technology and applications
Latest update time：2022-06-19
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Since physicist Nikola Tesla proposed the idea of wireless power transmission 100 years ago, "wireless charging" technology has made great progress, but progress in commercial applications has been slow. It was not until the popularity of mobile phone wireless charging in recent years that the technology of "wireless charging" became well known to the public. While helping mobile phone users get rid of the entanglement of cables, it began to penetrate into more application areas, from TWS headphones and micro IoT sensors to kitchen appliances and electric vehicles.
Wireless Charging Technologies and Standards
At present, there are several main ways to achieve wireless power transmission: electromagnetic induction (Inductive), magnetic field resonance (Resonant), radio frequency microwave (RF). Among them, the wireless charging standard that uses electromagnetic induction and resonance technology is the Qi specification of the Wireless Power Consortium (WPC); while the AirFuel Alliance mainly promotes resonance and RF technology.
Electromagnetic induction technology is the most mature technology on the market. Its basic principle is that when current passes through the transmitting coil, a magnetic field is generated, which generates an induced electromotive force on the nearby receiving coil and then generates current, thereby realizing the transfer of electric energy from the transmitting end to the receiving end. The Qi standard of the WPC Alliance adopts electromagnetic induction technology. This method has a relatively high conversion efficiency, but the transmission distance is short, only about 10mm. In addition, this method has certain requirements for the placement of the device. When charging, it is necessary to align the coil one by one, which is a bit inflexible and inconvenient for users.
Among all wireless charging products, electromagnetic induction is the most popular, including daily small appliances such as electric toothbrushes, electric shavers, and cordless phones, as well as smart terminals such as mobile phones and tablet computers. At present, the main challenges facing wireless charging technology based on electromagnetic induction are the stringent requirements for the placement of charging equipment, the limitation of charging distance, and the induction heating of coils.
Samsung and Android phone manufacturers have long added wireless charging functions to their flagship phone models, and Apple also began to support wireless charging when it released the iPhone 8 in 2017. They all support the Qi wireless charging standard, which brings great convenience to users. The wireless charging pad that is now familiar to ordinary consumers is a wireless charging transmitter. As long as it complies with the Qi specification, it can be wirelessly charged. In terms of the application of electromagnetic induction technology, domestic companies (including chip suppliers, wireless charger manufacturers, and mobile phone and terminal manufacturers) have been at the forefront of the wireless charging industry. Qi's application products in China are mainly mobile phones. This is the first stage, and it will be expanded to different categories or higher-power digital products in the future.
The Wireless Power Consortium (WPC), founded in 2008, currently has more than 650 members, and its Qi wireless charging standard has been supported by more than 3,000 products, including more than 2,600 transmitters and charging products. In addition to mobile phones, more than 120 car models currently support Qi wireless charging.
Like electromagnetic induction technology, magnetic field resonance technology also uses coils, but transmits electrical energy through resonance. Taking PowerbyProxi, which was acquired by Apple, as an example, the principle of its wireless charging technology is as follows:
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The mains voltage is converted to high-frequency alternating current (AC);
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The current is transmitted to the transmitting coil through the transmitting circuit;
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The current flowing through the transmitting coil generates a magnetic field, which causes the receiving coil in the receiving device within a certain distance to resonate;
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The receiving coil generates current;
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The current is converted to direct current (DC) by the receiving end circuit, which then charges the battery of the receiving device.
The advantage of resonance technology over induction technology is that the receiving and transmitting devices do not need to be strictly coupled and aligned. Wireless charging can be achieved with loose coupling, and the transmission distance is also longer, reaching 50mm.
The AirFuel Alliance, formed by the merger of A4WP and PMA, was established in 2015 and is now actively promoting resonance technology and RF technology to other application markets beyond mobile phones, including the Internet of Things, medical devices, and electric vehicles.
In terms of current wireless charging technology standards and alliances, the Qi Alliance has the largest number of members, including TI, Philips, HTC, Nokia, Samsung, Sony Ericsson, Best Buy and other well-known companies. Products of different brands, as long as they have the Qi logo, can be charged with Qi wireless chargers - overcoming 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 large-scale applications of wireless charging possible.
Due to the early establishment of the Qi Alliance, the large number of members, market recognition and strong compatibility, the Qi protocol has an absolute leading position in the low-power wireless charging market, especially in the mobile phone wireless charging market.
Wireless Charging Market Size and Growth Trends
According to statistics, in 2019, mobile phones with wireless charging function accounted for about 20% of shipments, and this penetration rate is expected to increase to 35% by 2022. At present, Apple's iPhone, AirPods and Apple Watch are all equipped with wireless charging as standard, while wireless charging of Android phones is penetrating from flagship phones to mid- and low-end models. According to Strategy Analytics, there will be more than 1 billion mobile phones with wireless charging function in the world in 2021, and the TWS wireless charging warehouse market will also grow strongly. There are about 515 million wireless charging receiving devices (RX) with Qi certification mark, and about 197 million wireless charging transmitters (TX). These devices include mobile phones, tablets, wearable devices, as well as aftermarket accessories and embedded chargers for cars and public places.
The total shipments of Qi-certified devices increased by 30% compared to 2020, and are expected to grow by an average of about 24% by 2025. From a regional market perspective, the Asia-Pacific region remains the largest wireless charging market, accounting for 39%, of which the Chinese market is the main driving force for the popularization of Qi wireless charging.
Mobile phone products are still an important segment of the wireless charging industry. In 2021, the market size of wireless charging for mobile phones was about 6.87 billion yuan, a year-on-year increase of 9.6%. As wireless charging becomes more and more popular on mobile phones, wireless charging will gradually rise in other types of terminal applications.
According to the report data on wireless charging transmitters by market research organization BCC Research, the global wireless charger market size was US$1.058 billion in 2017, and is expected to reach US$1.564 billion by 2022, with a compound annual growth rate of approximately 8.1%. According to a forecast by a domestic authoritative market research organization, the global wireless charger market will grow at a compound annual growth rate of 19.8% between 2021 and 2027. The main driving factors include the support of the national dual-carbon policy, the popularization of clean energy, and the development of mobile communication technology, which will provide new opportunities for the development of wireless charging.
After years of development, the wireless charging industry has formed a complete industrial chain, including solution design, chips, coils, magnetic materials and module manufacturing, among which solution design accounts for 30%; charging chips account for 28%; magnetic materials account for 21%; coils account for 14%; and module manufacturing accounts for 7%. Among these value nodes, solution design and chips have high technical barriers, accounting for about 60% of the value of the industrial chain, and are mainly monopolized by international chip giants such as STMicroelectronics, Renesas and Broadcom. Domestic companies are also gradually becoming stronger in the market for key wireless charging components. Domestic manufacturers such as ZTE, Xinwei Communication, Maxic and Inchip are gradually approaching international manufacturers in product technology and application design.
Wireless charging application scenarios and cases
For many years, academics and technology companies have been researching the technology and applications of wireless charging, but due to the lack of unified standards, its application is limited to specific fields and has never entered the mainstream commercial market. Now that the technology is relatively mature and industry standards are relatively complete, it should be a natural thing for wireless charging to enter consumers' daily lives and commercial application scenarios. Wireless charging for smartphones is just a burst point, and the Internet of Things and new energy vehicles will drive greater growth in wireless charging.
According to the size of charging power, the application of wireless charging can be roughly divided into the following categories:
a) Micropower devices (<5W): including smart watches, TWS headphones, wearable devices, smart sensors, low-power IoT devices and medical devices. The RF technology standards promoted by the AirFuel Alliance will become the main driving force for this market segment.
b) Low-power devices (5-15W): Smartphones are the leaders in this market segment and the entire wireless charging market. Other low-power electronic products include tablets, POS machines, cameras, and smart home devices. WPC Qi will continue to dominate this market segment, but the AirFuel RESONANT standard will also be more widely adopted.
c) Medium-power devices (30-65W, up to 200W): including smartphones, tablets, laptops, robots, drones, sweepers, lawn mowers, power tools, small appliances, and industrial IoT devices. Traditional devices that need to be plugged into a power cord for charging are likely to be replaced by wireless charging, and combined with smart control or display functions, traditional devices in this market segment will be revitalized. This market will also become a competitive high ground for WPC Qi and AirFuel RESONANT standards.
d) High-power devices (200W-25KW): including kitchen appliances, electric bicycles, AGVs, electric vehicles and other high-power electronic and electrical equipment. WPC is developing wireless charging standards for high-power devices such as kitchen appliances, electric bicycles and AGVs. The AirFuel RESONANT standard is progressing faster in this market segment. The most representative of these is WiTricity, a high-power wireless charging technology company that was spun off from MIT.
The charging power of medium and high power equipment terminals, especially smart terminals represented by mobile phones, has increased rapidly, from 5W at the beginning to 100W or even higher now, and some models of mobile phones are also equipped with reverse wireless charging technology, which can charge smart watches, TWS headphones and other devices. Mobile phone wireless charging applications must overcome technical difficulties such as thin body, efficiency, heat generation, alignment, material properties, space limitations and placement costs, so the design technology of the receiving chip inside the mobile phone is more complex and has higher technical barriers.
The following uses the wireless charging receiver chip of Maxicon with a charging power of 100W and 18W reverse charging as an example to illustrate the design of high-power applications in smart terminals. By adopting the self-created high-power RX+2:1 charge pump dual-chip architecture, the receiver chip MT5785 integrates everything needed for wireless charging reception, providing an output power of up to 100W, and also has an 18W reverse charging function, with a conversion efficiency of 98.5%. It supports the latest BPP and EPP certifications of WPC, and supports the proprietary wireless fast charging protocols of major mobile phone manufacturers, and can be widely used in smart phones, laptops, power tools and other fields. It is understood that Maxicon has successfully developed and mass-produced a full range of 1W~100W wireless charging receiver and transmitter chips, some of which are at the industry-leading level. Terminal products cover well-known brands such as Xiaomi, Honor, and Transsion.
Wireless charging chip manufacturers
International manufacturers with wireless charging technology and chip products include Renesas (acquired IDT and Dialog), ST, Broadcom, NXP and other first-class chip manufacturers. Domestic wireless charging chip manufacturers mainly include chip designers represented by Maxic, Fuda Semiconductor, E-Chong Wireless, and Inchip.
The success of wireless charging in mobile phone applications will promote the penetration of this emerging charging method into more application markets such as wearable devices, home appliances, power tools and even automobiles, which provides greater development space for wireless charging chip developers. Domestic wireless charging chip manufacturers represented by Maxim Sheng will seize more market share in the broader wireless charging market and even become the leader of the global wireless charging market by virtue of the technology and market experience accumulated in the field of mobile phone wireless charging.
Source: ittbank
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