Signal extraction circuit for wireless charging system communication

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By combining the design of filtering and demodulation circuits, the problems of signal interference and high cost in wireless charging systems are solved, achieving efficient signal extraction and flexible configuration to adapt to various application scenarios and enhancing the communication performance and flexibility of wireless charging systems.

CN224191930UActive Publication Date: 2026-05-01NINGBO DOUCHPOWER TECHNOLOGY CO LTD

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Patent Information

Authority / Receiving Office: CN · China
Patent Type: Utility models(China)
Current Assignee / Owner: NINGBO DOUCHPOWER TECHNOLOGY CO LTD
Filing Date: 2025-05-27
Publication Date: 2026-05-01

AI Technical Summary

Technical Problem

Existing wireless charging systems face complex electromagnetic interference and similar signal frequencies, making it difficult to accurately extract communication signals. Traditional signal extraction circuits are complex, costly, and inflexible, failing to meet the needs of different application scenarios.

Method used

The design combines filtering and demodulation circuits, including a rectifier module, a first filter module, an amplification module, a second filter module, and a comparator module. The filter type can be flexibly selected through the filtering circuit, and the demodulation circuit has a clear division of labor. The rectifier module adopts a dual-diode full-wave rectification, the amplification module adopts a differential amplifier circuit with an adjustable resistor network, and a two-stage low-pass filter structure is used to filter out interference and adjust the amplification factor.

Benefits of technology

It improves the accuracy and stability of signal extraction, reduces circuit costs, and can be flexibly configured according to different application scenarios to achieve half-duplex communication and low-power energy transmission, thus expanding the application scope of wireless charging technology.

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Abstract

The utility model discloses a signal extraction circuit for wireless charging system communication, which comprises a filter circuit and a demodulation circuit, the output end of the filter circuit is connected with the demodulation circuit, and the demodulation circuit comprises a rectifier module, a first filter module, an amplification module, a second filter module and a comparison module which are connected in sequence; the input end of the rectifier module receives a modulation signal from a wireless charging coil and rectifies the modulation signal; the first filtering module is used for filtering high-frequency harmonic interference; the amplification module is used for amplifying the signal; the second filtering module further filters the signal; the comparison module compares the filtering signal with a reference voltage and then outputs a square wave signal. According to the utility model, power signals can be accurately eliminated from complex mixed signals, clean and effective communication signals are obtained, the circuit cost is reduced, the circuit performance is improved, and the function of flexible configuration according to different application scenes and requirements is realized.

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Description

Technical Field

[0001] This utility model relates to the field of wireless charging technology, and more specifically, to a signal extraction circuit for communication in a wireless charging system. Background Technology

[0002] With the rapid development of wireless charging technology, it has been widely applied in many fields such as consumer electronics and electric vehicles. In wireless charging systems, achieving efficient and stable communication is crucial, affecting not only the safety and reliability of the charging process but also the realization of inter-device interaction. However, existing wireless charging systems face numerous challenges in communication. Firstly, complex electromagnetic interference exists during wireless charging. The power signal and communication signal have similar frequencies, making the communication signal susceptible to interference, thus making it difficult to accurately extract a clean communication signal from the received signal. For example, in scenarios where multiple devices are charging simultaneously, the electromagnetic signals generated by different devices intertwine, further exacerbating signal interference. Secondly, traditional signal extraction circuits are complex and costly, and perform poorly when processing weak communication signals, failing to meet market demands for low-cost, high-performance wireless charging systems. Furthermore, existing signal extraction circuits lack flexibility, unable to be adjusted flexibly according to different application scenarios and requirements, limiting the further expansion and application of wireless charging technology. Utility Model Content

[0003] The purpose of this invention is to provide a signal extraction circuit for communication in a wireless charging system. This invention can accurately remove power signals from complex mixed signals to obtain clean and effective communication signals, while reducing circuit costs, improving circuit performance, and enabling flexible configuration according to different application scenarios and requirements.

[0004] The technical solution of this utility model is as follows: a signal extraction circuit for wireless charging system communication, including a filtering circuit and a demodulation circuit, wherein the output terminal of the filtering circuit is connected to the demodulation circuit, and the demodulation circuit includes a rectifier module, a first filtering module, an amplification module, a second filtering module and a comparison module connected in sequence;

[0005] The rectifier module consists of a dual-diode full-wave rectifier circuit composed of a forward-parallel diode D1 and a reverse-parallel diode D2, and its input terminal receives a modulation signal from the wireless charging coil.

[0006] The first filtering module includes a first RC branch and a second RC branch connected in parallel, which are connected to the output of the rectifier module to filter out high-frequency harmonic interference;

[0007] The amplification module consists of an operational amplifier (OP) and an adjustable resistor network configured at the inverting input terminal to form a differential amplifier circuit. The input terminal is connected to the output terminal of the first filter module, and the amplification factor is adjusted by the adjustable resistor network.

[0008] The second filtering module includes a third RC branch, which is connected to the output of the amplification module to form a two-stage low-pass filter structure;

[0009] The comparison module includes a reference voltage divider network and a comparator COMP. The input of the comparison module is connected to the output of the second filter module. After comparing the filtered signal with the reference voltage, it outputs a square wave signal.

[0010] In the signal extraction circuit described above for wireless charging system communication, the anode of diode D1 is connected to the signal input terminal, and the cathode of diode D1 is connected to the input terminal of the first filter module; the cathode of diode D2 is connected to the signal input terminal, and the anode is grounded.

[0011] The aforementioned signal extraction circuit for wireless charging system communication, wherein the first filtering module includes:

[0012] Resistor R1 and capacitor C1 are connected in series to form the first RC branch;

[0013] Resistor R2 and capacitor C2 are connected in series to form the second RC branch.

[0014] The aforementioned signal extraction circuit for wireless charging system communication includes an amplification module that is a differential amplifier circuit, comprising an operational amplifier OP, resistors R3, R4, R6, and R7.

[0015] The non-inverting input terminal of the operational amplifier OP is connected to the output terminal of the first filter module via resistor R3, and the non-inverting input terminal of the operational amplifier OP is grounded via resistor R4.

[0016] The adjustable resistor network consists of resistors R5 and R6. The inverting input terminal of the operational amplifier OP is connected to the first filter module via resistor R5. The two ends of resistor R6 are connected to the inverting input terminal and the output terminal of the operational amplifier OP, respectively.

[0017] The aforementioned signal extraction circuit for wireless charging system communication includes a second filtering module comprising a third RC branch consisting of a resistor R7 and a capacitor C3; one end of the resistor R7 is connected to the output terminal of the operational amplifier OP, and the other end of the resistor R7 is connected to one end of the capacitor C3 and the comparator module; the other end of the capacitor C3 is grounded.

[0018] The aforementioned signal extraction circuit for wireless charging system communication includes a comparison module comprising a reference voltage divider network consisting of resistor R8 and capacitor C9, and a comparator COMP. One end of resistor R8 is connected to the second filter module, and the other end of resistor R8 is connected to one end of resistor R9 and the non-inverting input of comparator COMP. The other end of resistor R9 is grounded. The inverting input of comparator COMP is connected to a reference voltage, which is grounded.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This utility model adopts a design combining a filtering circuit and a demodulation circuit. The filtering circuit can flexibly select band-stop, high-pass, band-pass filters and their combinations to specifically eliminate power signal interference. For example, a band-stop filter can set the center frequency at the power signal frequency, effectively suppressing the power signal; a high-pass filter has its cutoff frequency set between the power signal and the communication carrier signal frequency, preventing low-frequency power signals from passing through, ensuring the purity of the communication signal, and greatly improving the accuracy and stability of signal extraction.

[0021] 2. The demodulation circuit of this utility model has clearly defined functions for each module, which work collaboratively. The rectifier module adopts a dual-diode full-wave rectifier circuit, which is simple in structure and efficiently converts the AC modulated signal into a unidirectional pulsating DC signal. The two-stage low-pass filter structure (the first filter module and the second filter module) is composed of different RC branches, which effectively filters out high-frequency harmonic interference and residual noise, making the signal smoother and more stable. The amplification module adopts a differential amplifier circuit composed of an operational amplifier and an adjustable resistor network, which can not only enhance the signal amplitude, but also flexibly adjust the amplification factor by adjusting the resistor to adapt to input signals of different intensities. The overall circuit structure is compact and reasonable, reducing costs while ensuring performance.

[0022] 3. This utility model can be flexibly configured according to different application scenarios and needs of the wireless charging system. In the wireless charging system, both the transmitter and receiver can use this circuit to achieve half-duplex communication and low-power energy transmission. For example, when the receiver is not connected to a battery, the transmitter can transmit low-power energy to the receiver as an auxiliary power source through a related resonant circuit; when the receiver is connected to a battery, it can provide auxiliary power to the transmitter and wake up the transmitter. In the idle state, it is disconnected from the mains power, meeting the needs of various usage scenarios and expanding the application scope of wireless charging technology. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a filtering method in a signal extraction circuit;

[0024] Figure 2 This is a schematic diagram of another filtering method for signal extraction circuits;

[0025] Figure 3 This is a schematic diagram of the demodulation circuit. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this is not intended to limit the present invention. The scope of protection of the present invention should include all the contents of the claims. Moreover, the following embodiments can enable those skilled in the art to have a more comprehensive understanding of the present invention.

[0027] Example: A signal extraction circuit for communication in a wireless charging system. The wireless charging system includes a transmitter circuit and a receiver circuit. The transmitter circuit includes a first resonant circuit and a third resonant circuit, and the receiver circuit includes a second resonant circuit and a fourth resonant circuit. Both the transmitter and receiver are equipped with signal extraction circuits. The wireless charging system transmits high-power energy through the first and second resonant circuits. The third and fourth resonant circuits are used to achieve half-duplex communication and low-power energy transmission between the transmitter and receiver. The half-duplex communication is based on near-field coupling, and the signal extraction circuit removes power signals to obtain clean and effective communication signals. The low-power energy transmission provides auxiliary power to either the receiver or the transmitter. When the receiver is not connected to a battery, the transmitter transmits low-power energy to the fourth resonant circuit through the third resonant circuit as auxiliary power to the receiver, enabling the wireless charging system to be self-powered. When the receiver is connected to a battery, the receiver transmits low-power energy to the third resonant circuit through the fourth resonant circuit to provide auxiliary power to the transmitter, thereby waking it up and disconnecting it from the mains (220V) input power in the idle state.

[0028] In this embodiment, the signal extraction circuit includes a filtering circuit and a demodulation circuit. Since the frequency of the transmitted power signal is lower than the frequency of the communication carrier signal, the filtering circuit can flexibly select band-stop, high-pass, and band-pass filters, as well as combinations thereof. Specifically, the center frequency of the band-stop filter should be set at the frequency of the power signal, the center frequency of the band-pass filter should be set at the frequency of the communication carrier signal, and the cutoff frequency of the high-pass filter should be set between the power signal frequency and the communication carrier signal frequency. For details, the signal extraction circuit can be found in [reference needed]. Figure 1 and Figure 2 Examples of various filter combinations are shown. The demodulation circuit converts the signal after filtering into a binary sequence signal that the processing module can recognize. Specifically, the demodulation circuit is as follows: Figure 3 As shown, it includes a rectifier module, a first filter module, an amplifier module, a second filter module, and a comparator module connected in sequence;

[0029] The rectifier module consists of a dual-diode full-wave rectifier circuit composed of a forward-parallel diode D1 and a reverse-parallel diode D2, with the input terminal receiving the modulation signal from the wireless charging coil. The anode of diode D1 is connected to the signal input terminal, and the cathode of diode D1 is connected to the input terminal of the first filter module. The cathode of diode D2 is connected to the signal input terminal, and the anode is grounded.

[0030] The first filtering module includes a first RC branch and a second RC branch connected in parallel, which are connected to the output of the rectifier module to filter out high-frequency harmonic interference; the first filtering module includes: a resistor R1 and a capacitor C1 connected in series to form a first RC branch; and a resistor R2 and a capacitor C2 connected in series to form a second RC branch.

[0031] The amplification module consists of an operational amplifier OP and an adjustable resistor network configured at the inverting input, forming a differential amplifier circuit. The input is connected to the output of the first filter module, and the amplification factor is adjusted via the adjustable resistor network. The amplification module is a differential amplifier circuit, comprising an operational amplifier OP, resistors R3, R4, R6, and R5. The non-inverting input of the operational amplifier OP is connected to the output of the first filter module via resistor R3, and the non-inverting input of the operational amplifier OP is grounded via resistor R4. The adjustable resistor network consists of resistors R5 and R6. The inverting input of the operational amplifier OP is connected to the first filter module via resistor R5. The two ends of resistor R6 are connected to the inverting input and output of the operational amplifier OP, respectively.

[0032] The second filtering module includes a third RC branch connected to the output of the amplification module, forming a two-stage low-pass filter structure; the second filtering module includes a third RC branch composed of resistor R7 and capacitor C3; one end of resistor R7 is connected to the output of operational amplifier OP, and the other end of resistor R7 is connected to one end of capacitor C3 and the comparator module; the other end of capacitor C3 is grounded;

[0033] The comparison module includes a reference voltage divider network and a comparator COMP. The input of the comparison module is connected to the output of the second filter module. After comparing the filtered signal with the reference voltage, a square wave signal is output. The comparison module includes a reference voltage divider network composed of resistor R8 and capacitor C9, and a comparator COMP. One end of resistor R8 is connected to the second filter module, and the other end of resistor R8 is connected to one end of resistor R9 and the non-inverting input of comparator COMP. The other end of resistor R9 is grounded. The inverting input of comparator COMP is connected to the reference voltage, and the reference voltage is grounded.

[0034] The demodulation circuit has the following functions:

[0035] The rectifier section consists of diodes D1 and D2. Utilizing the unidirectional conductivity of diodes, it converts the input AC signal into a unidirectional pulsating DC signal. During the positive half-cycle of the input AC signal, D1 conducts and D2 is cut off; during the negative half-cycle, D2 conducts and D1 is cut off, achieving full-wave rectification.

[0036] The filtering section consists of an RC filter circuit composed of resistors R1 and R2 and capacitors C1 and C2. Capacitors C1 and C2 bypass the AC component in the pulsating DC signal. Through the capacitive reactance characteristic, the AC component returns to ground more through the capacitor, while the DC component passes smoothly. Resistors R1 and R2 are used to limit the current. Together with the capacitors, they smooth the output DC signal.

[0037] The amplification (op-amp) section includes the operational amplifier OP and resistors R3, R4, R5, and R6. This is a non-inverting proportional amplifier circuit. The input signal is input from the non-inverting terminal, amplified, and output from the op-amp output terminal, enhancing the signal amplitude for easier subsequent processing.

[0038] The secondary filtering section consists of an RC filter circuit composed of resistor R7 and capacitor C3, which is used to further filter out high-frequency noise in the signal, making the signal purer and providing a stable input signal for the subsequent comparator.

[0039] The comparison section consists of a comparator COMP and resistors R8 and R9, connected to a reference voltage. The comparator compares the filtered signal with the reference voltage. When the input signal is higher than the reference voltage, the comparator outputs a high level; when the input signal is lower than the reference voltage, the comparator outputs a low level. The high and low level signals (pulse signals) are sent to the processing module for further processing.

[0040] As can be seen from the above embodiments, the wireless charging system near-field communication method and device of this utility model can be flexibly configured according to different application scenarios and needs, effectively realizing wireless charging and near-field communication functions, and has broad application prospects.

Claims

1. A signal extraction circuit for wireless charging system communication, comprising a filtering circuit and a demodulation circuit, wherein the output terminal of the filtering circuit is connected to the demodulation circuit, characterized in that: The demodulation circuit includes a rectifier module, a first filter module, an amplifier module, a second filter module, and a comparator module connected in sequence. The rectifier module consists of a dual-diode full-wave rectifier circuit composed of a forward-parallel diode D1 and a reverse-parallel diode D2, and its input terminal receives a modulation signal from the wireless charging coil. The first filtering module includes a first RC branch and a second RC branch connected in parallel, which are connected to the output of the rectifier module to filter out high-frequency harmonic interference; The amplification module consists of an operational amplifier (OP) and an adjustable resistor network configured at the inverting input terminal to form a differential amplifier circuit. The input terminal is connected to the output terminal of the first filter module, and the amplification factor is adjusted by the adjustable resistor network. The second filtering module includes a third RC branch, which is connected to the output of the amplification module to form a two-stage low-pass filter structure; The comparison module includes a reference voltage divider network and a comparator COMP. The input of the comparison module is connected to the output of the second filter module. After comparing the filtered signal with the reference voltage, it outputs a square wave signal.

2. The signal extraction circuit for wireless charging system communication according to claim 1, characterized in that: The anode of diode D1 is connected to the signal input terminal, and the cathode of diode D1 is connected to the input terminal of the first filter module; the cathode of diode D2 is connected to the signal input terminal, and the anode is grounded.

3. The signal extraction circuit for wireless charging system communication of claim 1, wherein: The first filtering module includes: Resistor R1 and capacitor C1 are connected in series to form the first RC branch; Resistor R2 and capacitor C2 are connected in series to form the second RC branch.

4. The signal extraction circuit for wireless charging system communication according to claim 1, characterized in that: The amplification module is a differential amplifier circuit, which includes an operational amplifier OP, resistor R3, resistor R4, resistor R6, and resistor R6. The non-inverting input terminal of the operational amplifier OP is connected to the output terminal of the first filter module via resistor R3, and the non-inverting input terminal of the operational amplifier OP is grounded via resistor R4. The adjustable resistor network consists of resistors R5 and R6. The inverting input terminal of the operational amplifier OP is connected to the first filter module via resistor R5. The two ends of resistor R6 are connected to the inverting input terminal and the output terminal of the operational amplifier OP, respectively.

5. The signal extraction circuit for wireless charging system communication according to claim 1, characterized in that: The second filtering module includes a third RC branch consisting of resistor R7 and capacitor C3; one end of resistor R7 is connected to the output terminal of operational amplifier OP, and the other end of resistor R7 is connected to one end of capacitor C3 and the comparator module; the other end of capacitor C3 is grounded.

6. The signal extraction circuit for wireless charging system communication according to claim 1, characterized in that: The comparison module includes a reference voltage divider network consisting of resistor R8 and capacitor C9, and a comparator COMP. One end of resistor R8 is connected to the second filter module, and the other end of resistor R8 is connected to one end of resistor R9 and the non-inverting input of comparator COMP. The other end of resistor R9 is grounded. The inverting input of comparator COMP is connected to a reference voltage, and the reference voltage is grounded.

7. The signal extraction circuit for wireless charging system communication according to claim 1, characterized in that: The filtering circuit is one or more of the following: a band-stop filter, a high-pass filter, and a band-pass filter.