Let’s talk about the working principle of wireless charging technology

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Let’s talk about the working principle of wireless charging technology [Copy link]

Wireless charging technology is derived from wireless power transmission technology. Low-power wireless charging often uses electromagnetic induction; high-power wireless charging often uses resonance (most electric vehicles use this method to charge). The power supply device (charger) transmits energy to the power-consuming device, which uses the received energy to charge the battery and also for its own operation. Since the charger and the power-consuming device transmit energy through the magnetic field, there is no need to connect the two with wires, so the charger and the power-consuming device can have no exposed conductive contacts. History of wireless charging In 1890, physicist and electrical engineer Nikola Tesla had already conducted wireless power transmission experiments and achieved AC power generation. The International System of Units of Magnetic Induction Intensity is also named after him. Tesla's idea of wireless power transmission is to use the earth as the inner conductor and the earth's ionosphere as the outer conductor. By amplifying the transmitter in radial electromagnetic wave oscillation mode, a low-frequency resonance of about 8Hz is established between the earth and the ionosphere, and then the surface electromagnetic waves surrounding the earth are used to transmit energy. However, due to insufficient financial resources, Tesla's bold idea was not realized. Although later generations have fully confirmed the feasibility of this plan in theory, the world has not yet achieved universal harmony, and it is impossible to broadcast energy and obtain it free of charge worldwide. Therefore, a great scientific idea was stillborn. On June 7, 2007, the research team of the Massachusetts Institute of Technology published its research results on the website of the American magazine Science. The research team applied resonance to the transmission of electromagnetic waves and successfully "caught" electromagnetic waves. They used copper coils as electromagnetic resonators, one coil was attached to the power transmitter and the other coil was attached to the power receiver. After the transmitter sends out electromagnetic waves of a certain frequency, they diffuse to the receiver through the electromagnetic field, and the power is wirelessly transmitted. After many tests, the technology, which they call "wireless power", has been successfully able to power a 60-watt light bulb two meters away. The farthest transmission distance of this technology can only reach 2.7 meters, but researchers believe that the power supply can already charge the battery within this range. And only one power supply needs to be installed to power the appliances in the whole house. In February 2014, computer manufacturer Dell joined the A4WP camp. At that time, the camp's relevant senior executives said that they would upgrade the technology to support wireless charging of ultrabooks from computer manufacturers such as Dell. Most traditional laptops on the market have a power supply power of more than 50 watts, but ultrabooks use Intel's low-power processors and will become the first laptops to use wireless charging. Before this, wireless charging technology has always been related to "small" mobile devices such as smartphones and small-sized tablets. However, A4WP ("Wireless Power Alliance"), one of the three major wireless charging camps, recently announced that its technical standards have been upgraded and the supported charging power has increased to 50 watts, which means that high-power devices such as laptops and tablets can also be wirelessly charged. Basic principles of wireless charging The basic principles of wireless charging are mainly two parts, one is electromagnetic induction, and the other is induced electromotive force. The main principle of the law of electromagnetic induction is that when a part of a closed circuit cuts the magnetic flux lines in a magnetic field, an induced electromotive force will be generated. With the induced electromotive force, electrons can be driven to form a current. Through this principle, we provide a constantly changing magnetic flux to the coil, and a current will be generated in the coil, and then this part of the current will be integrated into a direct current to charge the mobile phone. In other words, wireless charging is to form a magnetic field between the wireless charger and the electronic device to be charged, and then transmit electricity by carrying energy through the magnetic field. There is no physical contact between the mobile phone and the wireless charger. The voltage and current in the wireless are generated by magnetic field coupling, that is, a pair of closely coupled induction coils are used to achieve the conversion between electricity and magnetism. The model of induced electromotive force can be seen from the figure below. Coil 1 is integrated at the wireless charger end, and coil 2 is integrated at the mobile phone end. The radius of the coil at the charger end is larger than that at the mobile phone end. There is a certain distance between the two. When a certain sinusoidal current is applied to coil 1, a certain magnetic induction will be generated at coil 2. Classification of wireless charging technology Wireless charging technology can be divided into three types according to its principle and operation mode: electromagnetic induction, radio waves, and electromagnetic resonance. Electromagnetic induction is the use of electromagnetic induction between a pair of coils to achieve charging technology. There is a coil at both the transmitting end and the receiving end. The transmitting end is the wireless charger end, and the coil is integrated as the primary coil, also called the transmitting coil; there is also a coil at the mobile phone end, and the coil is integrated as the secondary coil, also called the receiving coil. When the current passes through the transmitting coil, a magnetic field is generated. When the receiving coil receives the magnetic field, electromagnetic induction is generated, thereby generating an electromotive force. With voltage, an induced current is generated, which can charge the mobile phone. For this technology, the distance between the two needs to be less than 1 cm, and the user needs to place the device to be charged on the surface of the wireless charger to charge. Radio waves are rarely used because of their huge space and high energy consumption. The basic principle is similar to the mining radio used in the early days. The micro-high-efficiency receiver can receive radio waves transmitted in space. Due to the huge space loss of this technology, it is generally only used in low-power electronic devices, and the distance between the receiving device and the transmitting device cannot exceed a few meters. The electromagnetic resonance transmission distance is relatively large. The diameter of the coil used in the experiment is as high as tens of centimeters. This method cannot be commercialized yet, because the coils used in commercial products are all a few centimeters, but if the size is too small, the power received by the receiving end will be reduced. However, with the continuous updating of technology, it is believed that wireless chargers based on the electromagnetic resonance principle can be widely used in future electronic products. Comparison between wireless charging and wired charging 1.Charging time of wireless and wired charging According to the design requirements of wireless chargers, the charging time of wireless chargers cannot exceed one hour of wired charging, and the total time cannot exceed 4 hours. We performed wireless charging and limited charging on the same mobile phone until it was fully charged, and obtained the charging time. The wired charging time was 110 minutes, the constant current was 750mA, and the process included trickle charging, constant current charging and constant voltage charging. The wireless charging time was 150 minutes, the constant current was 560mA, and the whole process also included trickle charging, constant current and constant voltage current. Analyzing the experimental results, the wireless charging time was 150 minutes, which was only 40 minutes longer than the wired charging time, and the total time did not exceed 4 hours, which fully met the design requirements. 2. Wireless charging efficiency In addition to testing the wireless charging time, the wireless charging efficiency was also tested. The results of the test showed that the average efficiency of wireless charging can reach 65%, which meets the design requirements. The maximum charging efficiency is 68.8%. Although the charging efficiency did not reach 65% during trickle charging and constant voltage charging, the average charging efficiency basically reached 65% in general. Wireless Charging Standards There are five mainstream wireless charging standards: Qi standard, Power Matters Alliance (PMA) standard, Alliance for Wireless Power (A4WP) standard, iNPOFi technology, and Wi-Po technology. 1. Qi Standard Qi is the "wireless charging" standard launched by the Wireless Power Consortium (WPC), the world's first standardization organization to promote wireless charging technology. It has two major characteristics: 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 has overcome the technical bottleneck of "universality" of wireless charging. Mobile phones, cameras, computers and other products can be charged with Qi wireless chargers, which makes it possible for large-scale application of wireless charging. The more mainstream wireless charging technologies in the market are mainly through three methods, namely electromagnetic induction, radio waves, and resonance, and Qi uses the most mainstream electromagnetic induction technology. In terms of technical application, Chinese companies have stood 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 categories or higher-power digital products in the future. 2. Power Matters Alliance Standard The PowerMatters Alliance standard was initiated by Duracell Powermat, which is a joint venture between Procter & Gamble and wireless charging technology company Powermat, and has relatively outstanding comprehensive strength. In addition, Powermat is also one of the supporting members of the Alliance for WirelessPower (A4WP) standard. AT&T, Google and Starbucks have joined the PMA Alliance (abbreviation of Power Matters Alliance). The PMA Alliance is committed to creating wireless power supply standards for mobile phones and electronic devices that meet the standards of the IEEE Association, 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 an SD card, and is embedded with components such as coils and electrodes for electromagnetic induction contactless charging. The card is thin and can be used by inserting it next to the battery of an existing smartphone. Using this card, many portable terminals can easily support 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 of South Korea and the aforementioned Powermat. The alliance, which also includes members such as Ever Win Industries, Gill Industries, PeikerAcustic and SK Telecom, aims to establish technical standards and industry dialogue mechanisms for wireless charging devices for electronic products, including portable electronic products and electric vehicles. 4. iNPOFi technology iNPOFi ("invisible power field") wireless charging is a new wireless charging technology. Its wireless charging series products use 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 radiation-free technology has no radiation, adopts electric field pulse mode, and does not generate any radiation. The test results of China Telecommunication Technology Laboratory show that the added value of radiation is almost zero. In terms of high efficiency, Telecommunication Technology Laboratory also determined that the charging transmission efficiency of products with this technology is as high as more than 90%, which completely changed the low efficiency of traditional wireless charging, which is less than 70% of the maximum. 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, managing the charging process to ensure high charging efficiency; and using a unified charging board to charge electronic products of any brand and model safely, conveniently and efficiently. In terms of safety, various safety issues in weak current charging are taken into consideration, such as electrostatic ESD protection, overcharge prevention, shock prevention, etc. Even if there is a problem with the power management of the powered device itself, the inpofi chip can automatically fuse to protect the electronic device 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, which is only 1/4 the size of a 50-cent coin. It can be easily integrated into any device and can also be integrated into various forms of wearable devices. This is something that traditional electromagnetic products cannot achieve. As a new generation of wireless charging technology standard, iNPOFi technology is efficient, green, convenient and economical. The charging device using this technology consists of a power transmitter and a power receiver. The size and thickness of the transmitter are comparable to those of an ordinary mobile phone. The receiver is embedded in a mobile phone protective case. The mobile phone is covered with a protective case and placed flat on the transmitter for charging. During the charging process, the mobile phone does not need to be plugged in any connecting wires. Relevant tests show that the electromagnetic radiation during the charging process is zero, and the power efficiency conversion 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; it realizes low-temperature charging and effectively guarantees the safety and life of the equipment and battery. 5. Wi-Po technology Wi-Po technology is a Wi-Po magnetic resonance wireless charging technology. It uses a high-frequency constant-amplitude alternating magnetic field generator to generate a 6.78MHz resonant magnetic field to achieve a longer transmission distance. This technology realizes communication control through Bluetooth 4.0, which is safe and reliable, and can support one-to-many synchronous communication. It also has over-temperature, over-voltage, over-current protection and foreign body detection functions. Since the carrier used in this technology is the space magnetic field, the energy will not be emitted like electromagnetic waves, so it will not cause radiation damage to the human body. Wi-Po magnetic resonance wireless charging can be applied to various scenarios such as mobile phones, computers, smart wearables, smart homes, medical equipment, electric vehicles, etc. The "wireless charging" standard launched by the World Wide Web Consortium (WPC) has two major features: convenience and universality. First, products of different brands can be charged with Qi wireless chargers as long as they have a Qi logo. Second, it has overcome the technical bottleneck of "universality" of wireless charging. Mobile phones, cameras, computers and other products can be charged with Qi wireless chargers, which makes it possible for large-scale application of wireless charging. The more 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. In terms of technical application, Chinese companies have stood 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 categories or higher-power digital products in the future. 2. Power Matters Alliance Standard The PowerMatters Alliance standard was initiated by Duracell Powermat, which is a joint venture between Procter & Gamble and wireless charging technology company Powermat, and has relatively outstanding comprehensive strength. In addition, Powermat is also one of the supporting members of the Alliance for Wireless Power (A4WP) standard. AT&T, Google and Starbucks have joined the PMA Alliance (abbreviation of Power Matters Alliance). The PMA Alliance is committed to creating wireless power supply standards for mobile phones and electronic devices that meet the standards of the IEEE Association, 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 an SD card, and is embedded with components such as coils and electrodes for electromagnetic induction contactless charging. The card is thin and can be used by inserting it next to the battery of an existing smartphone. Using this card, many portable terminals can easily support 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, PeikerAcustic and SK Telecom, aims to establish technical standards and industry dialogue mechanisms for wireless charging devices for electronic products, including portable electronic products and electric vehicles. 4. iNPOFi technology iNPOFi ("invisible power field") wireless charging is a new wireless charging technology. Its wireless charging series products use 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 radiation-free technology has no radiation, adopts electric field pulse mode, and does not generate any radiation. The test results of China Telecommunication Technology Laboratory show that the added value of radiation is almost zero. In terms of high efficiency, Telecommunication Technology Laboratory also determined that the charging transmission efficiency of products with this technology is as high as more than 90%, which completely changed the low efficiency of traditional wireless charging, which is less than 70% of the maximum. 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, managing the charging process to ensure high charging efficiency; and using a unified charging board to charge electronic products of any brand and model safely, conveniently and efficiently. In terms of safety, various safety issues in weak current charging are taken into consideration, such as electrostatic ESD protection, overcharge prevention, shock prevention, etc. Even if there is a problem with the power management of the powered device itself, the inpofi chip can automatically fuse to protect the electronic device 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, which is only 1/4 the size of a 50-cent coin. It can be easily integrated into any device and can also be integrated into various forms of wearable devices. This is something that traditional electromagnetic products cannot achieve. As a new generation of wireless charging technology standard, iNPOFi technology is efficient, green, convenient and economical. The charging device using this technology consists of a power transmitter and a power receiver. The size and thickness of the transmitter are comparable to those of an ordinary mobile phone. The receiver is embedded in a mobile phone protective case. The mobile phone is covered with a protective case and placed flat on the transmitter for charging. During the charging process, the mobile phone does not need to be plugged in any connecting wires. Relevant tests show that the electromagnetic radiation during the charging process is zero, and the power efficiency conversion 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; it realizes low-temperature charging and effectively guarantees the safety and life of the equipment and battery. 5. Wi-Po technology Wi-Po technology is a Wi-Po magnetic resonance wireless charging technology. It uses a high-frequency constant-amplitude alternating magnetic field generator to generate a 6.78MHz resonant magnetic field to achieve a longer transmission distance. This technology realizes communication control through Bluetooth 4.0, which is safe and reliable, and can support one-to-many synchronous communication. It also has over-temperature, over-voltage, over-current protection and foreign body detection functions. Since the carrier used in this technology is the space magnetic field, the energy will not be emitted like electromagnetic waves, so it will not cause radiation damage to the human body. Wi-Po magnetic resonance wireless charging can be applied to various scenarios such as mobile phones, computers, smart wearables, smart homes, medical equipment, electric vehicles, etc. The "wireless charging" standard launched by the World Wide Web Consortium (WPC) has two major features: convenience and universality. First, products of different brands can be charged with Qi wireless chargers as long as they have a Qi logo. Second, it has overcome the technical bottleneck of "universality" of wireless charging. Mobile phones, cameras, computers and other products can be charged with Qi wireless chargers, which makes it possible for large-scale application of wireless charging. The more 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. In terms of technical application, Chinese companies have stood 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 categories or higher-power digital products in the future. 2. Power Matters Alliance Standard The PowerMatters Alliance standard was initiated by Duracell Powermat, which is a joint venture between Procter & Gamble and wireless charging technology company Powermat, and has relatively outstanding comprehensive strength. In addition, Powermat is also one of the supporting members of the Alliance for Wireless Power (A4WP) standard. AT&T, Google and Starbucks have joined the PMA Alliance (abbreviation of Power Matters Alliance). The PMA Alliance is committed to creating wireless power supply standards for mobile phones and electronic devices that meet the standards of the IEEE Association, 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 an SD card, and is embedded with components such as coils and electrodes for electromagnetic induction contactless charging. The card is thin and can be used by inserting it next to the battery of an existing smartphone. Using this card, many portable terminals can easily support 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, PeikerAcustic and SK Telecom, aims to establish technical standards and industry dialogue mechanisms for wireless charging devices for electronic products, including portable electronic products and electric vehicles. 4. iNPOFi technology iNPOFi ("invisible power field") wireless charging is a new wireless charging technology. Its wireless charging series products use 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 radiation-free technology has no radiation, adopts electric field pulse mode, and does not generate any radiation. The test results of China Telecommunication Technology Laboratory show that the added value of radiation is almost zero. In terms of high efficiency, Telecommunication Technology Laboratory also determined that the charging transmission efficiency of products with this technology is as high as more than 90%, which completely changed the low efficiency of traditional wireless charging, which is less than 70% of the maximum. 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, managing the charging process to ensure high charging efficiency; and using a unified charging board to charge electronic products of any brand and model safely, conveniently and efficiently. In terms of safety, various safety issues in weak current charging are taken into consideration, such as electrostatic ESD protection, overcharge prevention, shock prevention, etc. Even if there is a problem with the power management of the powered device itself, the inpofi chip can automatically fuse to protect the electronic device 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, which is only 1/4 the size of a 50-cent coin. It can be easily integrated into any device and can also be integrated into various forms of wearable devices. This is something that traditional electromagnetic products cannot achieve. As a new generation of wireless charging technology standard, iNPOFi technology is efficient, green, convenient and economical. The charging device using this technology consists of a power transmitter and a power receiver. The size and thickness of the transmitter are comparable to those of an ordinary mobile phone. The receiver is embedded in a mobile phone protective case. The mobile phone is covered with a protective case and placed flat on the transmitter for charging. During the charging process, the mobile phone does not need to be plugged in any connecting wires. Relevant tests show that the electromagnetic radiation during the charging process is zero, and the power efficiency conversion 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; it realizes low-temperature charging and effectively guarantees the safety and life of the equipment and battery. 5. Wi-Po technology Wi-Po technology is a Wi-Po magnetic resonance wireless charging technology. It uses a high-frequency constant-amplitude alternating magnetic field generator to generate a 6.78MHz resonant magnetic field to achieve a longer transmission distance. This technology realizes communication control through Bluetooth 4.0, which is safe and reliable, and can support one-to-many synchronous communication. It also has over-temperature, over-voltage, over-current protection and foreign body detection functions. Since the carrier used in this technology is the space magnetic field, the energy will not be emitted like electromagnetic waves, so it will not cause radiation damage to the human body. Wi-Po magnetic resonance wireless charging can be applied to various scenarios such as mobile phones, computers, smart wearables, smart homes, medical equipment, electric vehicles, etc. 0 realizes communication control, which is safe and reliable, and can support one-to-many synchronous communication. It also has over-temperature, over-voltage, over-current protection and foreign object detection functions. Since the carrier used in this technology is the space magnetic field, the energy will not be emitted like electromagnetic waves, so it will not cause radiation damage to the human body. Wi-Po magnetic resonance wireless charging can be applied to various scenarios such as mobile phones, computers, smart wearables, smart homes, medical equipment, electric vehicles, etc. 0 realizes communication control, which is safe and reliable, and can support one-to-many synchronous communication. It also has over-temperature, over-voltage, over-current protection and foreign object detection functions. Since the carrier used in this technology is the space magnetic field, the energy will not be emitted like electromagnetic waves, so it will not cause radiation damage to the human body. Wi-Po magnetic resonance wireless charging can be applied to various scenarios such as mobile phones, computers, smart wearables, smart homes, medical equipment, electric vehicles, etc. 0 realizes communication control, which is safe and reliable, and can support one-to-many synchronous communication. It also has over-temperature, over-voltage, over-current protection and foreign object detection functions. Since the carrier used in this technology is the space magnetic field, the energy will not be emitted like electromagnetic waves, so it will not cause radiation damage to the human body. Wi-Po magnetic resonance wireless charging can be applied to various scenarios such as mobile phones, computers, smart wearables, smart homes, medical equipment, electric vehicles, etc. 0 realizes communication control, which is safe and reliable, and can support one-to-many synchronous communication. It also has over-temperature, over-voltage, over-current protection and foreign object detection functions. Since the carrier used in this technology is the space magnetic field, the energy will not be emitted like electromagnetic waves, so it will not cause radiation damage to the human body. Wi-Po magnetic resonance wireless charging can be applied to various scenarios such as mobile phones, computers, smart wearables, smart homes, medical equipment, electric vehicles, etc.