Technology Required for Mass Production of 300W High Power Wireless Charging

The common QI wireless charging products available in market transmit power through electromagnetic induction between coils. The maximum transmission power of standard specification is 15W. There are many specifications of the standard coil, and the design size of most of the coils in mass production is within 50mm*50mm and the induction distance is within 10mm. The commercialization of wireless charging products must realize three key functions: 1. Communications Protocol, 2. Power Transfer Control, 3. Foreign Object Detection. There are clear specifications and reference designs for the three key functions in the QI specification, but the specification applies to the maximum transmission power of 15W, which requires more advanced control technology to achieve mass production. This paper describes the technical difficulties and solutions to increase the transmission power to 300W with similar coil size and induction distance.

Figure 1. 300W wireless power transmission mod   

Figure 2. 300W wireless power transmission in operation

Communications Protocol

Wireless charging refers to the transmission of electricity from Transmitter to Receiver without a conductor connection. The source power input is changed into electromagnetic energy by Transmitter circuit drive coil, and the Receiver coil receives electromagnetic energy and transmits it into power output by the circuit. This technology is also called wireless power transmission. The source power is input to the Transmitter circuit, the driving coil converts it into electromagnetic energy, and the Receiver coil receives electromagnetic energy and transmits it into power output in the circuit This technology is also called wireless power transmission.

Transmitter detects whether a Receiver is close to its working range periodically when no Receiver is detected, that is, the Transmitter does not output power in the standby state. After the Receiver gets close to the working range, the data signal will be fed back to the Transmitter for identification, and this data content is the basis of compatibility. After it’s identified by the Transmitter, continuous power output, namely power transmission state, is started. In the process of power transmission, the Receiver will continuously feedback the data code to the Transmitter. When the Transmitter cannot receive the data code in the process of power transmission, the Receiver is regarded as leaving the working range, continuous power output will be cut off and the Transmitter will return to standby mode. The key of target recognition technology is the steady transmission of data codes between coils. The transmission of power between coils also functions as communication, also known in the industry as in-band communications. In the QI architecture, through the virtual load imposed on the Receiver coil, Receiver feedback data code to Transmitter. In the process of power transmission, the impedance change of Receiver coil will be reflected to Transmitter coil to change its signal amplitude. The data coding adopts differential bi-phase encoding mode, that is, the virtual load needs to be repeatedly applied to the coil so that the Transmitter coil signal has a high and low drop, and the Transmitter decodes its signal through the circuit and software. In the communication process, the virtual load will be imposed on the Receiver coil for a period of time so that the reflected signal generates a drop range. The more the virtual load is greater than the transmitted power, the more obvious the reflected high and low drop will be, and the time of the virtual load action will also consume extra power. In the application of 15W product in the QI products, this technical architecture can maintain the communication function between coils. However, when the transmission power is increased, the intensity of virtual load needs to be increased to maintain communication and the virtual load on the product cannot increase indefinitely with the increase of transmission power. Part of the solution to the communication problem after improving the power is external communication module, which transmits data through other wireless communication methods, also known as out-of-band communications in the industry. The external communication module will have the disadvantages of pairing verification and cost increase. The product prefers to complete the communication work on the power transmission coil for the sake of simple practical application and cost consideration.

Fu Da Tong Technology started to invest in the research and development of wireless charging technology in 2008. It took more than 10 years of research and development to develop the wireless power transmission power from the original 1W to the reference design of 300W, which was launched in 2019, and all technologies have been improved step by step. This paper continues to introduce the research and development achievements over the years and the current technology that can be mass-produced.

The company has been conducting communication technology research on the coil since 2018. Initially, the battery was used as the load in the charger architecture, and a switch was added between the Receiver coil and the battery load. The control switch was used to change the impedance of the Receiver coil and complete the function of data feedback. The disadvantage of using the battery as a load for modulation is that when the battery approaches full charge, the load characteristic will be lost and the communication will fail. In order to solve this problem, a solution is proposed to construct a virtual load on the coil for signal modulation. Element 231 in Figure 3 is the virtual load, and element 132 is the de-modulating circuit. Figure 4 illustrates the encoding of data by modulation duration. Each modulation state transition produces a high and low drop interval which is regarded as a bit, and the length of each interval indicates that the data content of this bit is "logic 0" or "logic 1".

Figure 3. United States Patent 8,412,963 FIG.3 (Applied in 2010)

Figure 4. United States Patent 8,412,963 FIG.9D (Applied in 2010)

The virtual load is used for signal modulation on the coil. When the transmission power increases, it is found that additional power consumption will occur during the use of load modulation, so it is necessary to shorten the use of load modulation time as much as possible. Referring to Figure 5, in order to shorten the asymmetric coding mode after using load modulation time, the non-modulation time segment without power consumption can be extended so that the coding can be easily identified, and the power loss can be reduced as much as possible during the modulation period.

Figure 5. United States Patent 8,810,072 FIG.18 (Applied in 2011)

In 2012 we developed a new coding mechanism that is still in use today. Figure6 shows the timing synchronous coding technology. Receiver produces signal pulse through modulation on the coil in a very short time, and Transmitter collects pulse signal for decoding. This technology focuses on the synchronization of encoding timing sequence. Both Receiver and Transmitter transmit data according to synchronization of timer. The correct modulation pulse will only appear in the pre-arranged allowable time range. Pulse signals outside the allowable time range will be considered noise exclusion. Pulse signals outside the permissible time range will be excluded as noise. This coding technique has two major advantages: 1. A very short modulation operation time is used to generate pulses, and the consumption power generated by the modulation action is greatly reduced. 2. It only analyzes the signal at the expected time, and the noise outside the expected time will be excluded, so it has anti-noise ability. With this coding technique, data transmission between coils can be accomplished on systems over 100W.

Figure 6. United States Patent 9,048,881 FIG.17 (Applied in 2012)

The purpose of establishing virtual load is to change the impedance on Receiver coil to reflect it to Transmitter coil to change its signal. The greater the difference between virtual load and transmission power, the more obvious the reflection effect. For example: when the transmission power is 10W, the virtual load used to modulate the signal is equivalent to 20W, it can produce obvious signal fluctuation; When the transmission power is increased to 100W, maintaining the modulated signal requires an obvious recognition that its virtual load is much higher than the equivalent of 100W, so the additional power consumption is not practical. The goal is to change the impedance on the Receiver coil, that is, in addition to increasing the virtual load, it can also reduce the load to achieve the modulation effect; Block 23 in Figure 7 is a half-bridge synchronous rectifier. Components 236 and 238 are added to the rectifier to control the operation of the rectifier, which can suspend the operation of the rectifier during the modulation to achieve the effect of short-term load reduction. This technology can maintain the coil data signal transmission function while increasing the transmission power, and reduce the power loss during modulation.

Figure 7. United States Patent 9,075,587 FIG.2 (Applied in 2012)

Timing synchronous coding has a fixed length of time for each data segment. Figure 8 is an example of this technique. Data is transmitted every 50ms and the decoding function is activated within the expected time range. In this technology, the noise received at an unexpected time will be filtered out. This technology can effectively improve the anti-noise ability. In wireless charging, the load change at the output end of the Receiver will also change the coil impedance. Transmitter coil signal not only contains modulation data from Receiver, but also contains noise caused by load or other factors, this technology can be completed in the past noise to take out the correct data code. The signal on the Transmitter coil comes from the modulation data of the Receiver, which also contains a lot of noise caused by load or other factors. This technique can remove the noise and take out the correct data code.

Figure 8. United States Patent 9,600,021 FIG.19 (Applied in 2013)

Through the short time modulation action, the modulation signal of Receiver has the jitter phenomenon in a small range on Transmitter coil. In Figure 9 and Figure 10, a hardware circuit is used to convert the jitter signal section into voltage fluctuation signal for decoding.

Figure 9. United States Patent 9,831,687 FIG.7 (Applied in 2015)

Figure 10. United States Patent 9,831,687 FIG.8 (Applied in 2015)

Only quality-stable modulating signals can construct quality-stable data transmission. Figure 11 shows the technology of alternating modulation at both ends of the coil on a Receiver, in which the switching signal on the coil is locked and Data modulation with fixed resonant cycles is arranged. The switching signal on the coil is locked and Data modulation with fixed resonant cycles is arranged to stabilize the quality of the modulating signal. Alternating modulation may suspend only one rectification phase, and the unsuspended rectification phase can continue to receive power and maintain power output during data modulation.

Figure 11. United States Patent 10,038,338 FIG.7 (Applied in 2015)

The modulation signal on the Transmitter coil needs to be de-modulated to restore the data code. The traditional technique is to use a filter to extract the low frequency modulation signal from the high frequency coil resonance signal. However, the limited performance of the filter is the biggest weakness of the system. When the power increases, the amplitude of the coil signal changes greatly, and the filter is difficult to operate accurately under the condition of large signal changes, the sensitivity of the filter can not be dynamically adjusted during operation, and the filter is difficult to accurately deal with the mixed signal of modulation signal and noise. Refer to Figure 12 and Figure 13. Since 2014, the company has been researching the signal de-modulation method without filter. The processor analyzes the signal based on the output frequency of the driver, i.e. the resonant period. The coil signal is input to the comparator to generate trigger signal. Based on the driver frequency, the trigger signal is stored in the internal memory of the microprocessor, and then the data code is analyzed by software. This technology evolves the de-modulation technology in wireless charging into a highly programmed mechanism that can automatically adjust with signal status during operation to improve the communication reliability between coils under high power wireless power transmission.

Figure 12. United States Patent 9,671,444 FIG.9 (Applied in 2014)

Figure 13. United States Patent 10,056,944 FIG.3 (Applied in 2014)

Refer to Figure 14 and Figure 15. Jitter can be generated by alternating modulation feedback from Receiver to Transmitter coil. This transient signal is different from the common load noise and can be used in signal analysis to provide data for decoding. The equivalent virtual load of Receiver operation modulation of this technology is very small, and the amplitude of signal jitter is relatively small. In 2016, the company developed a technology that accurately interprets Jitter's signal, separating the properly modulated signal from the noise generated by the load. In 2016, the company developed technology that can accurately parse jitter signals, correctly separating modulating signals from noise generated by load.

Figure 14. United States Patent 10,574,095 FIG.3 (Applied in 2019)

Figure 15. United States Patent 10,312,748 FIG.2 (Applied in 2016)

Filterless signal parsing is based on each driving cycle to parse the trigger signal to be saved in memory for decoding action afterwards. For example, if the driving frequency is 100KHz, there will be 100,000 trigger data per second. Such a large amount of data requires an efficient decoding program for data analysis, as shown in Figure 16. The trigger data of each section is disassembled by timer, and then the data code is restored. In the technology, the timing synchronization data coding and decoding technology is used to eliminate the noise interference occurring in the unarranged time sequence.

Figure 16. United States Patent 10,574,095 FIG.5 (Applied in 2019)

Fu Da Tong Technology has obtained 18 patents related to data encoding and decoding between wireless power transmission coils. The patent numbers, names and acquisition dates are listed below:

 8,098,043 Induction type power supply device(January 17, 2012)

 8,412,963 Power supplying and data transmitting method for induction type power supply system(April 2, 2013)

 8,810,072 High-power induction-type power supply system and its data transmission method(August 19, 2014)

 8,941,267 High-power induction-type power supply system and its bi-phase decoding method(January 27, 2014)

 8,981,600 Low-loss data transmission method for high-power induction-type power supply system(March 17, 2015)

 9,048,881 Method of time-synchronized data transmission in induction type power supply system(July 2, 2015) ; 9,075,587 Induction type power supply system with synchronous rectification control for data transmission(July 7, 2015)

 9,600,021 Operating clock synchronization adjusting method for induction type power supply system(March 21, 2017)

 9,600,022 Operating clock synchronization adjusting method for induction type power supply system(March 21, 2017)

 9,671,444 Current signal sensing method for supplying-end module of induction type power supply system(July 6, 2017)

 9,831,687 Supplying-end module for induction-type power supply system and signal analysis circuit therein(November 28, 2017)

10,038,338 Signal modulation method and signal rectification and modulation device(July 31, 2018)

10,056,944 Data determination method for supplying-end module of induction type power supply system and related supplying-end module(August 21, 2018)

10,312,748 Signal analysis method and circuit(June 4, 2019)

10,574,095 Decoding method for signal processing circuit and signal processing circuit using the same(February 25, 2020)

10,587,153 Intruding metal detection method for induction type power supply system and related supplying-end module(March 10, 2020)

10,594,168 Intruding metal detection method for induction type power supply system and related supplying-end module(March 17, 2020)

10,686,331 Signal modulation method and signal rectification and modulation device(June 16, 2020)。

Power transfer control

Wireless charging transmits energy from Transmitter to Receiver, and the operation objective is to provide energy for Transmitter to meet the requirements of back-end load of Receiver; If the power demand of Receiver load is large, the Transmitter energy will be increased; if the power demand of Receiver load is small, the Transmitter energy will be reduced. In the actual products, a voltage regulator is installed between the Receiver coil and the output load. If the transmission energy is too large, the voltage regulator configured at the Receiver will bear more conversion loss. If the transmission energy is too small, the load will receive less energy than the design intended. In addition, the relative position of Transmitter coil and Receiver coil also affects the energy transmission efficiency. When the relative distance between the coils increases, the Transmitter needs to send more energy to make up for the demand of the Receiver load; on the contrary, when the distance is shortened, the Transmitter must reduce the output power to avoid the Receiver receiving additional power. Transmitter sending too much energy will cause damage to Receiver hardware. In the QI specification, power adjustment depends on the feedback of "Control error message" from the Receiver to Transmitter. This mechanism has two disadvantages: first, the speed of adjustment is slow and the data transmission speed is limited. Each power adjustment can only be carried out after data transmission is completed; second, the communication between coils is easy to be interrupted when the load power varies greatly, and the power output cannot be adjusted when the communication is interrupted. These two disadvantages result in the inadequate ability of the actual products applying this technology to cope with dynamic loads.

Fu Da Tong Technology has introduced a number of innovative technologies in power regulation. The power adjustment can be realized quickly by optimizing the coil transmission energy without communication data, and the power adjustment can be optimized by detecting the coil relative distance.

As shown in Figure 17 and Figure 18, in the early stage of development the output power of Transmitter is adjusted By controlling the output frequency to the driver and driver voltage.

Figure 17. United States Patent 8,417,359 FIG.13 (Applied in 2010)

Figure 18. United States Patent 8,519,667 FIG.4 (Applied in 2011)

Figure 19. A large dynamic range can be controlled by adjusting the driver frequency to change the output power. The designed drive frequency is always higher than the resonant frequency on the coil. Reducing the drive frequency will improve the power output. If the reduced drive frequency is lower than the coil resonance point, the output power will begin to decline. In the technology of the Fu Da Tong Technology, the algorithm avoids the driving frequency lower than resonant point frequency in the adjustment process and keeps the system running stably.

Figure 19. United States Patent 8,772,979 FIG.8 (Applied in 2011)

The Transmitter adjusts the power after receiving the power demand message from the Receiver, and the output power is determined by the amplitude of the resonant signal on the Transmitter coil. The peak voltage of the resonant signal is a quantifiable output power. The signal is an AC signal of approximately 100KHz whose frequency varies with the operation of the system. In the traditional technology, the voltage is sampled by the detecting circuit, but the signal frequency is not fixed and the dynamic range is large, and the accuracy of sampling through the detecting circuit is low; However, the accurate coil voltage is the basis of power adjustment calculation, and the power output cannot be controlled accurately if the coil voltage measurement is not accurate. In addition, the output of the detection circuit has a certain delay, and the measurement of voltage by the detecting circuit is slow. After the power adjustment changes the driving condition, detect the coil voltage change, and then judge whether the adjustment needs to continue or has been completed. Delayed measurement results will result in slow control response speed.

Refer to Figure 20 and Figure 21. The company proposed a resonant signal peak voltage measurement technology without detecting circuit. This technology can accurately measure the peak voltage of the coil by detecting the resonant signal offset and setting the trigger time of the Analog-to-digital converter at the peak position of the wave. Each resonant period can be taken out and the current measured value has no delay defect. This technology provides accurate voltage values for use in calculating power regulation, which can accurately and quickly adjust power to the target value.

Figure 20. United States Patent 9,960,639 FIG.3 (Applied in 2015)

Figure 21. United States Patent 11,128,180 FIG.1 (Applied in 2017)

Power regulation requires two key parameters, measured output and target output. The measured output value refers to the latest measured data of power output. After comparing the set target output value, it is decided to increase or decrease the power output. The previously mentioned technology starts power adjustment upon receiving the power demand message from the Receiver. The process of transmitting the message is that the Receiver detects the power demand through the modulation and demodulation technology between the coils, and then the power target is adjusted by the judgment content of Transmitter decoding. This process can only perform a maximum of 20 power adjustments per second with the technology currently available on the market. Such response speed cannot meet dynamic load requirements. Figure 22 shows a technique for detecting coil load state, in which the load state of the coil is calculated by measuring the peak position of the resonance waveform and comparing the driving sequence, and after the coil load state, the power is adjusted by driving signal phase shift adjustment technology. The time from detection to adjustment can be shortened to one resonant cycle, and the power adjustment speed can reach 100,000 times per second for the 100KHz drive frequency system, which is thousands of times faster than the previous technology.

Figure 22. United States Patent 10,153,665 FIG.7 (Applied in 2017)

In wireless charging, the relative position of Transmitter coil and Receiver coil is not fixed, and the relative distance and dislocation distance of the coil will affect the transmission efficiency. For example, when the output load of Receiver is fixed, if the relative distance of coil is far or the dislocation distance is long, the efficiency will be worse. Worse efficiency means that Transmitter needs to transmit more power to meet the demand of Receiver load, and worse efficiency also means that Transmitter's additional transmission power is lost. Figure 23 is a schematic diagram of relative distance and dislocation of coils. To optimize coil transmission efficiency, the technology needs to be able to measure coil relative positions for the system to determine power regulation. There will be a resonant frequency in the resonant circuit formed by the coil and the capacitor. The deviation caused by the capacitor in the operation process is very small and can be ignored in practice, but the inductance of the coil will change due to the proximity of the adjacent magnetic material, and the resonant frequency will be affected when the inductance changes. The relative positions of the coils can be calculated by means of resonance frequency detection. This information can be used to optimize power regulation operations.

Figure 23. United States Patent 10,673,287 FIG.2 (Applied in 2019)

Fu Da Tong Technology has obtained 10 patents related to power control of wireless power transmission. The patent numbers, names and acquisition dates are listed below:

8,217,621 Frequency modulation type wireless power supply and charger system(July 10, 2012)

8,417,359 Power transmission method of high-power wireless induction power supply system(April 9, 2013)

8,519,667 Mobile wireless charger system(August 27, 2013)

8,772,979 Method for power self-regulation in a high-power induction type power source(July 8, 2014)

8,860,365 Inductive charging method for vehicles(October 14, 2014)

9,045,050 Inductive charging method for vehicles(June 2, 2015)

9,628,147 Method of automatically adjusting determination voltage and voltage adjusting device thereof (April 18, 2017)

9,960,639 Supplying-end module of induction type power supply system and voltage measurement method thereof(May 1, 2018)

10,153,665 Method for adjusting output power for induction type power supply system and related supplying-end module(December 11, 2018)

10,673,287 Method and supplying-end module for detecting receiving-end module(June 2, 2020)。

Foreign Object Detection

Metal foreign object between coils is the biggest safety problem in wireless power transmission. IPC (International Patent Classification) proposed a special corresponding classification of the technology "H02J 50/60 • Responsive to the presence of foreign objects, E.g. detection of living beings [2016.01] ". It can be seen that this technology is a very important item in products. When something hazardous is detected between the coils, the power transmission is stopped and not restarted until the hazard is eliminated. Two FOD technologies are proposed in the QI specification: Power Loss Accounting and Quality Factor; Power loss Accounting means to monitor the difference between the output power of Transmitter and the receiving power of Receiver during power transmission. If there is a metal foreign object between the coils, the metal foreign object will absorb some of the energy and cause the difference to become larger. This approach is suitable for low power, but when the power is increased, this approach is not feasible; The receiving power of Receiver is 5W, and the transmission efficiency may be 60%~70% due to the influence of the relative position of the coils, so the Transmitter output power may be between 7.1W~8.3W, and the calculated difference is 2.1W~3.3W. The offset is 1.2W during normal operation. If a metal foreign body absorbing 2W energy is added between the coils, the increased difference is greater than the normal offset of 1.2W difference, and the presence of a metal foreign body can be easily identified. By increasing the received power by 10 times under the same conditions, the offset of normal operation will be as high as 12W. If the difference is caused by a metal foreign object absorbing 2W, it is impossible to determine whether the difference is caused by coil deviation or the metal foreign object. The technology also cannot detect objects that absorb less power, such as paper clips, which absorb less energy but still pose a risk of burning when its temperature adds up. Quality Factor means to measure the Quality state of the coil before power transmission, but the Quality of the coil is not fixed after leaving the factory, so this method requires calibration and adjustment. In addition, this technology also needs additional detecting circuits.

Since 2010, Fu Da Tong Technology has been researching metal foreign object identification technology on Transmitter coil, which is the most difficult project to develop in wireless charging. Refer to Figure 24. The company developed the early technology in 2013. The coil amplitude reference curve is established in the process of wireless charging transmission, and the deviation between the current voltage and the reference curve is compared in the process of power transmission. If there is metal foreign object invading, the coil amplitude will change abnormally, and the metal foreign object can be identified after comparison.

Figure 24. United States Patent 9,413,197 FIG.5 (Applied in 2013)

Refer to Figure 25 to observe the change in attenuation of resonant signal during suspension of driver and switching of output potential. In 2014, it’s found that, in the drive operation, the coil resonance signal will enter the self-resonant state when it stops driving, and the amplitude of the signal will gradually decay. The attenuation speed is affected by the resistance around the coil. When there is a metal object around, the electromagnetic energy generated during the coil resonance will be absorbed to make the resonance attenuation speed faster. This feature is a physical phenomenon. The key of the technology is how to measure signal attenuation and identify the presence of metal foreign objects.

Figure 25. United States Patent 10,114,396 FIG.5B (Applied in 2015)

Figure 26 shows the self-resonant signal attenuation technology in power transmission. After the driver is turned off, the coil will start to self-resonant, and its resonant frequency is composed of the coil's own inductance and the matching capacitance. The resonant frequency will change with the change of the coil's inductance. After stopping the drive, the current resonant frequency must be measured first to capture the attenuation peak of the subsequent self-resonance. Multiple peak voltages must be taken out to calculate the attenuation speed and determine whether there is metal foreign object invasion.

Figure 26. United States Patent 10,289,142 FIG.7 (Applied in 2016)

When the Transmitter is in standby state and before it is connected with the Receiver and transmits power, the Transmitter also observes the self-resonant attenuation signal after a short drive to identify whether there is metal foreign matter on the Transmitter coil. Figure 27 shows the measurement of self-resonant signal in standby mode. The presence of metal objects around the Transmitter coil causes the self-resonant signal to decay quickly. The technology is very sensitive to detect small metals that may be hazardous, and wireless power transmission will not be activated to ensure safety when foreign metal objects are found.

Figure 27. United States Patent 10,587,153 FIG.4 (Applied in 2018)

In the process of power transmission, after suspending the drive and observing the speed of self-resonant attenuation of the coil, it is very difficult in practical technology to reengage the drive to continue power transmission; For example, assuming that the resonant frequency is 100KHz, the whole process from drive suspension to reengagement of drive will not exceed 1/10,000th of a second. Even if the drive is suspended for only 1/10,000th of a second, the wireless power transmission efficiency will be affected. As shown in Figure 28, the operation of suspending the drive, detecting the attenuation signal speed, and reengaging the drive output needs to be controlled by program, and the signal is processed by algorithm to identify the state of metal foreign object intrusion. If there is metal foreign object intrusion, the power transmission will be cut off to ensure safety.

Figure 28. United States Patent 10,594,168 FIG.4 (Applied in 2019)

In addition to metal foreign bodies, NFC devices can also be placed on coils by mistake. The NFC device has an antenna, and the power of wireless power transmission is too strong for its antenna, and the NFC device placed on the coil will be burned as soon as the wireless power transmission is started. The practice of the industry is to install an dedicated module for NFC on the Transmitter to detect NFC, which will increase the cost of hardware. Figure 29 shows a technology that can detect NFC devices using a simple component combined with algorithm. It is a low-cost NFC detection technology that can be mass-produced.

Figure 29. United States Patent 10,615,645 FIG.1 (Applied in 2019)

Fu Da Tong Technology has obtained 8 patents related to foreign object detection technology in wireless power transmission. The patent numbers, names and acquisition dates are listed below:

9,413,197 Inductive power supply system and intruding metal detection method thereof(August 9, 2016)

10,114,396 Induction type power supply system and intruding metal detection method thereof(October 30, 2018)

10,289,142 Induction type power supply system and intruding metal detection method thereof( May 14, 2019)

10,615,645 Power supply device of induction type power supply system and NFC device identification method of the same(April 7, 2020)

10,630,113 Power supply device of induction type power supply system and RF magnetic card identification method of the same(April 21, 2020)

10,630,116 Intruding metal detection method for induction type power supply system and related supplying-end module(April 21, 2020)

10,951,063 Supplying-end module of induction type power supply system and signal detection method thereof(March 16, 2021)

11,128,180 Method and supplying-end module for detecting receiving-end module(September 21, 2021) 。

Coil Design

Wireless power transmission is realized through coils, which are designed to change the sensing range and improve transmission efficiency. The key of coil design after power increase lies in average energy distribution and reduction of heat loss.

The figure 30 in below just shows a strip coil structure for long and narrow devices.

Figure 30. United States Patent 8,754,609 FIG.2 (Applied in 2012)

And the figure 31 shows the design of a high-power wireless power transmission module, which is a strong solid structure integrating coil and circuit board cooling device.

Figure 31. United States Patent 10,600,547 FIG.1 (Applied in 2018)

Figure 32 shows a coil winding method, which can make the energy evenly distributed and solve the problem of over-concentration of energy when the relative distance of the coil is too close after the coil is enlarged. This design can achieve high efficiency in all coil relative positions.

Figure 32. United States Patent 10,643,787 FIG.4 (Applied in 2018)

Fu Da Tong Technology has obtained 6 patents related to coil design technology in wireless power transmission. The patent numbers, names and acquisition dates are listed below:

8,729,854 Slot-type induction charger(May 20, 2014)

8,754,609 Wireless charging coil structure in electronic devices(June 17, 2014)

10,002,707 Induction coil structure for wireless charging device(June 19, 2018)

10,600,547 Induction type power supply system and coil module thereof(March 24, 2020)

10,643,787 Induction type power supply system and coil module thereof(May 5, 2020)

10,784,042 Induction type power supply system and coil module thereof(September 22, 2020)

The mass production of high power wireless charging technology will encounter some obstacles; The actual coil quality is difficult to control. Power control needs to be adjusted by algorithms that can adapt to coil deviation, accurate detection method of metal foreign object is needed to ensure safe use of users, and communication technology between coils needs to be reliable for stable operation. These technologies, which take years of research and development to come to fruition, are now integrated into the IC, and product developers who take the IC can add the technology to the product of mass production by following the reference design.