ЛОГОТИП УГКПБ
Basic Introduction
Definition and Technology
A wireless charger refers to a charger that is connected to a terminal device that needs to be charged without a traditional charging power cord. It adopts the latest wireless charging technology. By using the magnetic field generated between the coils, it can magically transmit electric energy. Inductive coupling technology will become a bridge connecting charging base stations and equipment.
Advantages and Disadvantages
Wireless charging technology obtained 20 patents in 2007. A variety of devices can use one charging base station, making corded charging scenarios for cell phones, MP3 players, power tools, and other power adapters obsolete. The advantage of wireless charging technology lies in its convenience and versatility. Однако, its disadvantage is low efficiency and its ability to only provide electric energy.
Historical Process
Historical Discovery
Back in the 1830s, Michael Faraday discovered that changes in the surrounding magnetic field would induce an electric current in a wire. In the 1890s, the Serbian-born scientist Nikola Tesla applied for the first patent. К сожалению, research in this area was delayed for a century due to low transmission efficiency and safety hazards.
Subsequent Development
Professor Xu Shuyuan from the City University of Hong Kong successfully developed a “wireless battery charging platform” in the early years, which can automatically charge several electronic products on a charging platform through low-frequency electromagnetic fields. Researchers at the Massachusetts Institute of Technology have also made progress in wirelessly transmitting electricity. Soljacic’s design for non-radiative wireless energy transmission has a distance limit, and they aim to increase efficiency to 70% к 80% within three to five years.
Принцип работы
Resonance and Induction
Physicists have long known that energy is efficiently transferred between two objects that resonate at the same frequency. Wireless charging technology takes advantage of this principle, applying the principle of electromagnetic wave induction and related AC induction technology. It uses corresponding coils at the sending and receiving ends to send and receive induced AC signals for charging.
Practical Application
A new type of wireless charger, originally invented by a British company, looks like a plastic mouse pad equipped with a dense array of small coils to generate a magnetic field and transmit energy to a dedicated charger. The receiving coil, made of magnetic alloy wound with wire, can be easily attached to electronic equipment. This new invention allows multiple devices to be charged simultaneously anywhere on the “mouse pad,” and the magnetic field generated is weak enough to not affect nearby items that use magnetic recording data.
Principles of Wireless Charging
The wireless charging system mainly adopts the principle of electromagnetic induction and realizes energy transmission through energy coupling through coils. As shown in the figure, when the system is working:
- The input terminal converts AC mains power into DC power through the full-bridge rectifier circuit, or directly supplies power to the system with a 24V DC terminal.
- After passing through the power management module, the output direct current is converted into high-frequency alternating current by the 2M active crystal oscillator and supplied to the primary winding.
- The energy is coupled through two inductive coils, and the current output by the secondary coil is converted into direct current by the receiving conversion circuit to charge the battery.
A changing magnetic field will produce a changing electric field, and vice versa. Their magnitudes are related to their rate of change, and the rate of change of a sinusoidal function results in another sinusoidal function. Hence, electromagnetic waves can propagate, and the generation of the coil’s induced voltage is related to the change in magnetic flux. Таким образом, the changing magnetic field inside the coil generates an induced voltage, completing the charging process.
Mobile Phone Wireless Charging
Mobile phone wireless charging is a relatively novel charging method. Its principle is straightforward: separating the primary and secondary of ordinary transformers to achieve wireless purposes. Notably, the working rate of wireless charging is high, and even the iron core can be discarded, with the direct coil achieving the function of energy transfer.
Basic Features of Wireless Charging Technology
Safety
From a theoretical perspective, wireless charging technology is harmless to human safety. The resonance principle used in wireless charging is magnetic field resonance, which only transmits between coils resonating at the same frequency, while other devices cannot accept the band. The magnetic field used is itself harmless to the human body. Однако, being a new technology, some people may have initial concerns, akin to when Wi-Fi and mobile phone antenna poles first emerged. In reality, the technology itself is harmless.
Magnetic Resonance
Maiyuan’s wireless charging technology uses magnetic resonance to transmit charges in the electric and magnetic fields between the charger and the device. The coil and capacitor form a resonance between the charger and the device.
Wide Applications
Maiyuan claims that this system can be widely used in the future, such as charging areas for electric vehicles and power transmission for computer chips. The charging time required by the charging system developed by this technology is significantly reduced compared to current methods.
High Conversion Rate
The conversion rate of Maiyuan wireless charging is several percentage points higher than that of wired charging. High conversion is crucial for the global application of wireless chargers. Однако, wireless charging technology is limited by distance. For future development, it is necessary to solve the problem of precise positioning of the wave band and magnetic field range for long-distance transmission.
Core Chip Challenges
The core chip is a significant challenge in the application of wireless charging technology in products. Precise radiation range control, magnetic field frequency, and other controls are implemented by chips.
Problem Summary
Market Application Development Bottleneck
- Core Wireless Charging Technology Imperfections
- Difficulty in Achieving Long-Distance Transmission
- High Hardware Requirements for Long-Distance Positioning
- Controlled and Small Height Matching of Magnetic Field Resonance
- Limited Application Range
- Market Factors – Developers are hesitant to invest heavily in technology research and development due to consumer psychology.
Radiation Hazard
MIT researchers state that the body responds strongly to electric fields but barely to magnetic fields, suggesting the system would not affect human health. Однако, this is speculative. Some researchers express concern, and further experiments are necessary before real-life application. As an electronic charging product, the charger itself emits radiation, but the wireless charger’s power is small, charging time is long, and the radiation produced is minimal, posing little harm to people.
Unified Port
To avoid unnecessary waste and generate more electronic waste, China is implementing unified standardization of mobile phone charger ports. Wireless charging technology is poised to become popular, usable not only for mobile phones but also for digital cameras, iPhones, iPads, and notebooks. Japan’s Fujitsu aims to extend this success from portable electronics to charging electric vehicles. Their ultimate goal is to set up public “charging points” on streets, providing convenient 24-hour all-weather charging services for portable digital devices and electric vehicle users. Wireless chargers are smarter and energy-efficient. Although their efficiency is about 70%, equal to wired charging equipment, they have an automatic shutdown function when fully charged, avoiding unnecessary energy consumption. Performance acceptance rates are continuously improving.
Mobile Phone Built-in Charging Receiver and Unified Wireless Charging Standard
By integrating a charging receiver into mobile phones and establishing a unified wireless charging standard, the adoption and convenience of wireless charging can be further enhanced.
Overview of Wireless Charging Technology
To realize wireless charging of mobile phones and other products, there must be two parts: the transmitter, which is connected to the power supply and responsible for transmitting electric energy to a wide space, and the receiver, which is generally installed on electronic products and used to receive electric energy. Wireless charging technology has begun to be used in mobile phone products. Taking the iPhone as an example, wireless charging manufacturers have refitted it and installed a kind of “clothes” similar to “apple peel”. As a wireless charging receiver, it appears in the form of adding a mobile phone charging case, but related modified products can be launched in China. Dubbed the “Qi Door,” the case supports both iPhones and BlackBerrys, giving users early access to the feature without having to replace their phones. In early 2013, the wireless charging receiver will be fully “slimmed down” and become a wireless charging receiving chip built into mobile phones, only as big as a fingernail. Nokia, Philips, LG, Samsung, Sony Ericsson, iPhone, HTC, Google, ZTE, Sharp, RIM, and many other internationally renowned mobile phone manufacturers all support this technology, and wireless chargers may also be bundled with mobile phones for sale.
Compatibility and the Qi Standard
The Importance of Compatibility
The key to wireless charging of mobile phones is compatibility, and the Qi standard can ensure brand compatibility. Wireless charging technology mainly uses electromagnetic technology. The transmitter converts the current into electromagnetic, and the mobile phone uses the built-in chip receiver to convert the electromagnetic into current to charge the mobile phone. The key to the promotion of wireless charging technology is to ensure that the wireless chargers of various manufacturers are compatible.
The Qi Standard
The formulation of the Qi standard enables wireless charging to have a unified technical specification and ensures the compatibility of the same charger with multiple brands and products. Menno Treffers, chairman of the Wireless Charging Alliance, said that the Qi wireless charging standard uses electromagnetic induction technology, which is more efficient and safer than other technologies. The Qi wireless charging standard includes three aspects: interface, производительность, and regulations. This is a considerable challenge to the popularization of wireless charging technology. Поэтому, mobile phones that pass the Qi standard can be powered by any Qi-certified charging base station, base, or other rechargeable devices. Qi’s first pre-requirement for devices is no higher than 5 watts, which may be a big limitation for some manufacturers who want laptops to also use wireless charging technology.
Market Availability of Qi Standard Products
Manufacturers have launched Qi standard wireless charging products, and the market is extensive. The world’s largest battery and portable lighting equipment manufacturer Energizer (Energizer) said that it will soon launch a wireless charger product that supports the Qi standard, and will first bring a new wireless charging experience to Apple iPhone3GS and Blackberry Blackberry Curve8900 users. В то же время, according to data provided by market research company iSuppli, the wireless charging equipment market reached a scale of 14 billion US dollars in 2013. Philips has already started making new phones that include wireless charging. The Philips X723 mobile phone has already appeared, and it features a 3.2-inch 240X400 screen with GPS and a 3-megapixel camera. The good news is that the machine comes standard with a wireless charger XeniumQ1 (Qi wireless charging alliance standard), but the specific launch time and price have not yet been disclosed.
Receive Antenna
Although this article focuses on chargers, it also provides an overview of receiving antennas. Because this type of wireless charging device is essentially a transformer, the primary is installed in the charger, and the secondary is installed in the terminal.
Choosing a Good Charging Antenna
Because the receiving antenna that does not match the charger will cause current fluctuations in the charging circuit, how to choose a good charging antenna?
Terminal Antenna Needs Magnetic Shielding
If the charging antenna is only a hollow coil, when nearby metal objects approach, it will cause eddy current, which will reduce the charging efficiency, prevent the energy of the charger from radiating out, increase the current, and cause the charger to heat up.
Magnetic Medium Selection
The magnetic medium selected by the charger is divided into two categories: organic magnetic materials and inorganic magnetic materials. The organic magnetic material can be made very thin and warped, which is suitable for bonding the back cover of the mobile phone and used in the mobile phone; the inorganic magnetic material is made of sintered ferrite, which is fragile and suitable for installation in large spaces.
