Wireless charging circuit for detecting foreign matters

Abstract

The invention discloses a wireless charging circuit for detecting foreign matters. The wireless charging circuit comprises a transmitting end and a receiving end. The transmitting end generates an alternating magnetic field through a high-frequency full-bridge inversion module, and performs coded modulation based on a unique preset device number. The receiving end senses the magnetic field through coupling and samples and decodes the magnetic field to realize three-stage verification with the transmitting end, and the three-stage verification comprises wireless communication verification, encryption key verification and equipment identity verification. The control module determines whether to start charging or output a metal foreign matter alarm signal according to the verification result. According to the scheme, the hierarchical safety verification process is completed before charging, so that the safety of wireless energy transmission and the accurate recognition capability of the system on the foreign matter are ensured, the stability and reliability of the wireless charging system are improved, the abnormal problem of fire catching caused by heating of the foreign matter in the charging process is avoided, and the charging safety is improved. Meanwhile, the method is suitable for wireless power supply application scenes supporting a security authentication mechanism.

Description

Technical Field

[0001] The present application relates to the field of wireless charging technology, and in particular to a wireless charging circuit for detecting foreign objects. Background Art

[0002] In recent years, with the development of wireless power transmission technology, wireless charging has been widely used in consumer electronics, medical devices, electric vehicles, and other fields. Wireless charging systems based on the principles of electromagnetic induction or magnetic resonance coupling typically include a transmitter and a receiver, enabling contactless energy transfer in space. However, during the wireless charging process, the presence of metal foreign objects in the charging area may cause energy loss, electromagnetic interference, and even safety hazards such as overheating and burning. Therefore, improving the accuracy and responsiveness of metal foreign object detection in wireless charging systems has become a focus of current research and industry attention.

[0003] In the existing technology, most foreign object detection methods mainly rely on temperature sensors, current change monitoring and other methods for judgment. However, these methods have defects such as response delay, high misjudgment rate or can only detect after charging has started, which makes it difficult to meet the high requirements for system stability and user safety.

[0004] Furthermore, some wireless charging devices lack effective authentication mechanisms, making them vulnerable to interference sources or unauthorized access, posing security risks. Therefore, there is an urgent need for a wireless charging system that combines foreign object detection and multi-level authentication to verify device legitimacy and environmental safety before charging begins. Summary of the Invention

[0005] The present application provides a wireless charging circuit for detecting foreign objects, so as to solve the common abnormal problem of low foreign object detection accuracy in wireless charging systems in the prior art, which may cause heat and fire during charging.

[0006] In a first aspect, the present application provides a wireless charging circuit for detecting foreign objects, wherein the wireless charging circuit for detecting foreign objects includes a transmitting end and a receiving end; The transmitter includes a transmitter control module, a high-frequency full-bridge inverter module, a transmitter coil resonance module, and a transmitter wireless communication module; The receiving end includes a receiving end coil resonance module, a receiving end control module, a receiving end coil sampling module and a receiving end wireless communication module; The receiving end control module interacts with the transmitting end wireless communication module through the receiving end wireless communication module, and the transmitting end wireless communication module interacts with the transmitting end control module; A device number is preset in the transmitter control module, and the preset device number is a unique device number of the transmitter; The transmitter control module modulates the high-frequency full-bridge inverter module based on the preset device number to generate an alternating magnetic field; The receiving-end coil resonance module is coupled to the transmitting-end coil resonance module, and the receiving-end coil resonance module senses the alternating magnetic field and outputs an AC signal; The transmitting end and the receiving end complete three-stage verification, the three-stage verification including wireless communication verification, encryption key verification and device identity verification; If the verification is successful, the transmitting end control module sends a charging signal to the receiving end control module; The receiving end control module starts the charging process in response to the charging signal; If the verification fails, the transmitting end control module determines that there is a foreign object in the transmitting end coil resonance module and outputs an alarm signal.

[0007] Optionally, the wireless communication verification process includes: The transmitting end wireless communication module establishes a communication connection with the receiving end wireless communication module; In response to the connection status of the transmitting-end wireless communication module and the receiving-end wireless communication module, wireless communication verification is completed.

[0008] Optionally, the encryption key verification process includes: The same encryption key is preset in the transmitting end control module and the receiving end control module; The transmitting end control module and the receiving end control module are matched by exchanging encryption keys to complete encryption key verification.

[0009] Optionally, the device identity authentication process includes: The receiving end coil sampling module samples the AC signal and sends the sampling result to the receiving end control module; The receiving end control module obtains the transmitting end device number according to the sampling result, and sends the transmitting end device number to the transmitting end control module; The transmitter control module matches the transmitter device number with the preset device number to complete device identity authentication.

[0010] Optionally, it is characterized in that the wireless communication connection is restarted after verification fails at any stage, and when the number of restarts reaches a preset threshold, a metal foreign body alarm signal is output.

[0011] Optionally, the receiving end coil sampling module includes a diode rectifier circuit and a multi-stage voltage divider circuit; The diode rectifier circuit is used to convert the AC signal output by the receiving end coil resonance module into a positive half-cycle AC signal; The multi-stage voltage divider circuit is used to convert the positive half-cycle AC signal into sampling data suitable for decoding.

[0012] Optionally, the high-frequency full-bridge inverter module includes a MOS tube switch logic circuit; The transmitter control module performs code modulation on the MOS tube switch logic circuit based on the preset device number to generate an alternating magnetic field, and the code modulation method includes at least one of frequency keying, amplitude keying and on-off keying.

[0013] Optionally, when the coded modulation method adopts frequency keying, the frequency of the transmitted signal is changed within a period to distinguish between binary numbers 0 and binary numbers 1.

[0014] Optionally, when the coded modulation method adopts amplitude keying, the amplitude of the transmission power is changed within a period to distinguish binary data, wherein a low amplitude is a binary number 0 and a high amplitude is a binary number 1.

[0015] Optionally, when the coded modulation method adopts on-off keying, binary data is distinguished by interrupting power transmission within a period, wherein the power transmission interruption state is a binary number 0, and the power continuous transmission state is a binary number 1.

[0016] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art: (1) Improve the security of the wireless charging system: By introducing a three-stage authentication mechanism (wireless communication authentication, encryption key authentication, and device authentication), the legitimacy of the device is confirmed before charging, effectively preventing illegal access and impersonation.

[0017] (2) Enhanced metal foreign body detection capability: Output an alarm signal when the verification failure reaches the retry number threshold, so as to identify the interference of foreign objects before charging starts, and effectively avoid safety hazards such as overheating and energy loss caused by foreign objects.

[0018] (3) Realize contactless identity data transmission and identification: The transmitter modulates the device number in the alternating magnetic field for near-field transmission, and the receiver recognizes the device number through coil induction and sampling decoding, which improves recognition efficiency and has a simple structure.

[0019] (4) Support multiple modulation modes to improve signal compatibility and decoding accuracy: The coded modulation mode supports at least one of frequency keying, amplitude keying and on-off keying, adapts to different transmission environments, and improves system robustness and decoding recognition rate.

[0020] (5) It has an adaptive retry and alarm mechanism to improve system stability: When a verification stage fails, the system has an automatic retry and threshold judgment mechanism, which can decide whether to alarm or restart the connection based on the actual communication and decoding status, thereby improving the system's fault tolerance.

[0021] (6) High sampling accuracy and fast response speed: The sampling module composed of diode rectification and multi-stage voltage divider circuit helps to quickly and accurately extract magnetic field signals and improve the efficiency and reliability of device number decoding.

[0022] (7) The structural modules are clear and easy to integrate and promote: The system takes the control module as the core, and combines wireless communication, coding modulation, magnetic field transmission and sampling decoding modules to facilitate the collaborative development of software and hardware and the subsequent product engineering implementation. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0025] Figure 1 A schematic diagram of the module structure of a wireless charging circuit for detecting foreign objects provided in an embodiment of the present application; Figure 2 A schematic diagram of a circuit for a transmitter in a wireless charging circuit for detecting foreign objects provided in an embodiment of the present application; Figure 3 A circuit diagram of a receiving end in a wireless charging circuit for detecting foreign objects provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] The disclosure below provides many different embodiments or examples for implementing different configurations of the present invention. To simplify the disclosure of the present invention, the components and configurations of specific examples are described below. Of course, these are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or configurations discussed.

[0028] like Figure 1 As shown, Figure 1 A schematic diagram of the module structure of a wireless charging circuit for detecting foreign objects provided in an embodiment of the present application.

[0029] All modules below describe their corresponding Figure 2-Figure 3 You can refer to the middle position Figure 1 The label description, such as Figure 1 As shown, the wireless charging circuit of the present application includes a transmitter 100 and a receiver 200, wherein the transmitter 100 includes a transmitter control module 101, a high-frequency full-bridge inverter module 102, a transmitter wireless communication module 103, a transmitter sampling module 104, a transmitter coil resonance module 105, a serial communication module 106, a DC input filter module 107, a transmitter DC / DC+LDO module 108, and a transmitter RGB module 109.

[0030] The receiving end 200 includes a receiving end control module 201, a receiving end coil resonance module 202, a receiving end coil sampling module 203, a receiving end wireless communication module 204, a full-bridge rectifier module 205, a filter module 206, a rectifier and filter module 207, a receiving end DC / DC+LDO module 208, a receiving end RGB module 209, a battery load 210, a receiving end serial communication module 211, and a receiving end coil sampling module 212.

[0031] The transmitter includes: a transmitter control module for overall control of the wireless charging system; a high-frequency full-bridge inverter module, connected to the transmitter control module, for performing power conversion and outputting an excitation current based on a control signal output by the control module; a transmitter wireless communication module, for exchanging information with a receiver wireless communication module; a transmitter sampling module, for collecting electrical parameters such as the transmitter's input voltage, input current, and the voltage at the transmitter coil coupling port; and a transmitter coil resonance module, connected to the output of the high-frequency full-bridge inverter module, for generating an alternating magnetic field based on the excitation current.

[0032] The receiving end includes: a receiving end control module for receiving control instructions, processing receiving end data, and storing preset battery configuration parameters; a receiving end wireless communication module for transmitting battery configuration parameters and sampled data from the receiving end control module to the transmitting end wireless communication module to achieve information exchange; a receiving end coil sampling module, connected to the battery pack, for collecting actual charging parameters of the receiving end, including charging current, battery voltage, and temperature; and a receiving end coil resonance module, magnetically coupled to the transmitting end coil resonance module, for receiving an alternating magnetic field and inducing high-frequency alternating current.

[0033] During actual operation, the receiving-end coil sampling module collects parameters such as the receiving-end charging current, battery voltage, and temperature in real time. The receiving-end control module sends the above-mentioned sampling parameters together with the preset battery configuration parameters stored internally to the transmitting-end control module. The information is transmitted through the wireless link between the receiving-end wireless communication module and the transmitting-end wireless communication module.

[0034] The transmitter sampling module collects operating parameters of the transmitter, including input voltage, input current and coupling port voltage of the transmitter coil resonance module, and transmits the sampled data to the transmitter control module.

[0035] The transmitter control module comprehensively analyzes the current charging stage and load requirements based on the received preset battery configuration parameters, receiver parameters, and transmitter parameters, and outputs a control signal to regulate the switching state of each MOS tube in the high-frequency full-bridge inverter module.

[0036] After receiving the control signals, the high-frequency full-bridge inverter module outputs a forward or reverse excitation current to the transmitter coil resonant module based on the control logic of the first and second control signals, thereby generating an alternating magnetic field of a specific frequency and power. This alternating magnetic field is transmitted to the receiver coil resonant module via spatial magnetic coupling, where the receiver coil generates high-frequency alternating current, providing energy for subsequent rectification, filtering, and charging processes.

[0037] The receiving end control module interacts with the transmitting end wireless communication module through the receiving end wireless communication module, and the transmitting end wireless communication module interacts with the transmitting end control module; A device number is preset in the transmitter control module, and the preset device number is a unique device number of the transmitter; The transmitter control module modulates the high-frequency full-bridge inverter module based on the preset device number to generate an alternating magnetic field; The receiving-end coil resonance module is coupled to the transmitting-end coil resonance module, and the receiving-end coil resonance module senses the alternating magnetic field and outputs an AC signal; The transmitting end and the receiving end complete three-stage verification, the three-stage verification including wireless communication verification, encryption key verification and device identity verification; If the verification is successful, the transmitting end control module sends a charging signal to the receiving end control module; The receiving end control module starts the charging process in response to the charging signal; If the verification fails, the transmitting end control module determines that there is a foreign object in the transmitting end coil resonance module and outputs an alarm signal.

[0038] In this embodiment of the present application, the transmitter control module presets a unique device number to identify the transmitter. When the receiver initiates the verification process, the receiver control module establishes a connection with the transmitter wireless communication module via the receiver wireless communication module and interacts with the transmitter control module. The transmitter wireless communication module is responsible for forwarding the received communication request and verification information to the transmitter control module.

[0039] During the authentication phase, the transmitter control module modulates and controls the high-frequency full-bridge inverter module based on the preset device ID. For example, the transmitter control module can use PWM control signals to change the conduction timing of the MOS transistor switches in the inverter module, and modulate the device ID code into the alternating magnetic field using methods such as frequency-shift keying (FSK), amplitude-shift keying (ASK), or on-off keying (OOK).

[0040] Under modulation, the transmitter coil resonant module generates an alternating magnetic field carrying the device number. The receiver coil resonant module spatially couples to this field, senses this field, and outputs an AC signal. This AC signal is rectified and voltage-divided by the receiver coil sampling module before being sent to the receiver control module for decoding. The decoded device number is then returned to the transmitter via the receiver wireless communication module for matching.

[0041] The system completes a three-stage verification process in sequence, including: wireless communication verification: ensuring that a communication link is established between the transmitter and the receiver; encryption key verification: handshake matching based on the pre-stored symmetric encryption keys of both parties; device identity verification: completing device number transmission, sampling, decoding and comparison.

[0042] If all three phases of verification pass, the transmitter control module sends a charging start signal to the receiver control module. The receiver control module responds to this signal by turning on the receiver power circuit and initiating the charging process. If any phase of verification fails, the transmitter control module determines that there may be an interference source or metal foreign object, outputs an alarm signal, and terminates charging.

[0043] Furthermore, the wireless communication verification process includes: The transmitting end wireless communication module establishes a communication connection with the receiving end wireless communication module; In response to the connection status of the transmitting-end wireless communication module and the receiving-end wireless communication module, wireless communication verification is completed.

[0044] In the embodiment of the present application, after the receiving end is powered on, the receiving end wireless communication module initiates a communication request by broadcasting, and the transmitting end wireless module responds after listening to the request, completing the 2.4 GHz link connection, and the control modules of both parties confirm the communication status as the first stage of verification.

[0045] like Figure 2 and Figure 3 As shown, the transmitter 100 includes a transmitter wireless communication module 103, which is a 2.4GHz wireless communication chip pre-configured for active scanning mode. The receiver 200 includes a receiver wireless communication module 204, which is also a 2.4GHz chip pre-configured for discoverable mode. The receiver wireless communication module 204 is directly connected to the receiver control module 201 and is powered by the receiver DC / DC+LDO module 208. When the receiver 200 is placed in the coupled magnetic field of the transmitter coil, the receiver coil resonance module 202 induces an alternating magnetic field and outputs an AC signal. This signal is converted into direct current by the rectifier and filter module 207, and then stabilized to 3.3V by the receiver DC / DC+LDO module 208, which powers the receiver control module 201 and the receiver wireless communication module 204 for startup.

[0046] Specifically, the wireless communication verification process includes: The transmitter control module 101 activates the wireless communication module 103 and initiates an active scan in the 2.4 GHz frequency band, covering all available channels to detect the receiver broadcast signal; The receiving-end wireless communication module 204 immediately broadcasts a broadcast signal containing a device type identifier after power is supplied; After the transmitting end wireless communication module 103 captures the broadcast signal, it sends a connection request; The two parties establish a link through the handshake protocol, exchange MAC addresses and communication parameters, and complete the three-way handshake; If the packet loss rate is less than the set threshold, the connection status is marked as successful. When the connection status is successful, the wireless communication verification is passed and the next stage of encryption key verification is triggered; If the packet loss rate is greater than or equal to the set threshold, the connection status is marked as failed, and the transmitter control module 101 responds to the failure status and automatically restarts the wireless communication connection after failure. When the number of restarts reaches the preset threshold, if it still fails, it is determined that the verification has failed, and a metal foreign body alarm signal is output. A flashing signal is output through the RGB light indicator module 209, and at the same time, the failure of the wireless communication verification is reported to the main control host computer, and there is suspected interference from metal foreign bodies.

[0047] In a possible implementation, the receiving-end control module 201 records the connection timestamp and the transmitting-end MAC address for subsequent interactions such as device identity authentication.

[0048] Furthermore, the encryption key verification process includes: The same encryption key is preset in the transmitting end control module and the receiving end control module; The transmitting end control module and the receiving end control module are matched by exchanging encryption keys to complete encryption key verification.

[0049] In an embodiment of the present application, the control modules of both parties each pre-store a symmetric encryption key (such as a 128-bit AES key). After establishing communication, they exchange random numbers and encryption summaries through a handshake protocol to verify key consistency, which serves as the second stage of encryption key verification.

[0050] like Figure 2 and Figure 3 As shown, during the device production phase, the same 128-bit AES encryption key is burned into each wireless charging system transmitter control module 101 and receiver control module 201. The same key pair is written simultaneously to the paired transmitter and receiver through the production line fixture to ensure unique matching.

[0051] Specifically, the encryption key verification process includes: When the device leaves the factory, the transmitter control module and the receiver control module each preset a set of identical symmetric encryption keys, such as a fixed-length digital sequence. The key is stored in a protected storage area of ​​both parties and is not transmitted in plain text.

[0052] After receiving the verification signal, the transmitter control module generates a random number as verification data. It encrypts the random number using a locally pre-set encryption key and sends the encrypted ciphertext to the receiver via the transmitter wireless communication module.

[0053] After receiving the encrypted ciphertext, the control module on the receiving end decrypts it using its own preset key to obtain the decrypted result. Subsequently, the transmitting end sends the original random number back to the receiving end in plaintext, and the receiving end compares the decrypted result with the plaintext data to ensure consistency.

[0054] If the decryption result of the receiving end is consistent with the plaintext random number, it means that the encryption key used by the transmitting end and the receiving end is the same and the match is successful. At this time, the receiving end control module feeds back the "key verification passed" information to the transmitting end through the receiving end wireless communication module.

[0055] If the decryption results are inconsistent, or the key verification process is not completed within the set time, the control module will determine that the encryption key is inconsistent and the verification has failed. The transmitter can record the failure status, and the control module can enter the retry logic. If the number of retries reaches the set threshold, the subsequent verification process will not continue.

[0056] Furthermore, the device identity verification process includes: The receiving end coil sampling module samples the AC signal and sends the sampling result to the receiving end control module; The receiving end control module obtains the transmitting end device number according to the sampling result, and sends the transmitting end device number to the transmitting end control module; The transmitter control module matches the transmitter device number with the preset device number to complete device identity authentication.

[0057] The receiving end coil sampling module includes a diode rectifier circuit and a multi-stage voltage divider circuit; The diode rectifier circuit is used to convert the AC signal output by the receiving end coil resonance module into a positive half-cycle AC signal; The multi-stage voltage divider circuit is used to convert the positive half-cycle AC signal into sampling data suitable for decoding.

[0058] After completing wireless communication verification and encryption key verification, the system continues to enter the third stage, device identity verification, which is used to confirm whether the transmitter is a pre-authorized device.

[0059] The transmitter control module modulates the high-frequency full-bridge inverter module based on a preset unique device ID. This control modulates the device ID into a modulation signal by varying the conduction timing of the switches in the inverter circuit, using a coding method (such as frequency keying, amplitude keying, or on-off keying). The modulated signal is radiated into space via the transmitter coil resonant module in the form of an alternating magnetic field.

[0060] The receiving coil resonant module forms a spatial coupling with the transmitting end, sensing the alternating magnetic field generated by the transmitting end and outputting an AC signal. This AC signal is processed by the receiving coil sampling module, including: using a diode rectifier circuit to convert the AC signal into a unidirectional half-wave signal; using a multi-stage resistor divider circuit to compress the signal to a voltage range suitable for sampling by the analog-to-digital converter; and the receiving control module performs high-speed sampling on the divided signal to obtain a voltage sequence reflecting the device number modulation content.

[0061] The receiving control module digitally processes the sampling results, identifying and decoding the waveform according to the preset modulation method. For example, if frequency keying is used, the control module counts the frequency changes of the waveform to correspond to different binary bits; if amplitude keying is used, it identifies the voltage amplitude changes corresponding to 0 or 1; if on-off keying is used, it detects the presence or absence of the signal to determine the data bit.

[0062] After decoding is complete, the receiving control module recovers the transmitter's device ID data. The decoded transmitter device ID is sent to the transmitting wireless communication module via the receiving wireless communication module. Upon receiving this ID, the transmitting control module compares it with its locally pre-set device ID. If the two match, verification is considered successful; if not, verification fails.

[0063] If the verification is successful, the transmitter control module sends a "start charging" command to the receiver, and the receiver control module turns on the subsequent power supply circuit and enters the normal charging mode; if the verification fails and the comparison is not successful after multiple failures, the transmitter control module can trigger the alarm logic, determine that there may be foreign object interference and stop energy transmission.

[0064] In the embodiment of the present application, this embodiment is designed for the safety and robustness of the wireless charging system. At any stage of identity authentication between the transmitter and the receiver, if there is a verification failure such as communication interruption, decryption error or identity mismatch, the system will automatically execute a retry mechanism and output a foreign object alarm signal through the RGB light indicator module 209 flashing signal if multiple retries still fail, to prompt the user or the upper system to intervene.

[0065] Furthermore, the high-frequency full-bridge inverter module includes a MOS tube switch logic circuit; The transmitter control module performs code modulation on the MOS tube switch logic circuit based on the preset device number to generate an alternating magnetic field, and the code modulation method includes at least one of frequency keying, amplitude keying and on-off keying.

[0066] When the coded modulation method adopts frequency keying, the frequency of the transmitted signal is changed within a period to distinguish between binary numbers 0 and binary numbers 1.

[0067] When the coded modulation method adopts amplitude keying, the amplitude of the transmission power is changed within a period to distinguish binary data, wherein a low amplitude is a binary number 0 and a high amplitude is a binary number 1.

[0068] When the coded modulation method adopts on-off keying, binary data is distinguished by interrupting power transmission within a period, wherein the power transmission interruption state is a binary number 0, and the power continuous transmission state is a binary number 1.

[0069] In this embodiment, the high-frequency full-bridge inverter module on the transmitter side converts the modulated signal output by the control module into an alternating current, which drives the transmitter coil resonant module to generate an alternating magnetic field. This module not only converts electrical energy but also performs coding and modulation functions, making it a key component in the system for implementing device number modulation and transmission.

[0070] The high-frequency full-bridge inverter module adopts a full-bridge topology, with four N-channel power MOS transistors forming the bridge switch unit, designated Q1, Q2, Q3, and Q4. The output terminal is connected to a series inductor L1 and resonant capacitor C1, forming a transmitter coil resonant module.

[0071] The transmitter control module stores a unique device number and converts it into a binary bit stream (such as 64 bits). It then modulates and drives the MOS tube by controlling the switching logic. Depending on the modulation mode, the control strategy is as follows: (1) Frequency-Shift Keying (FSK): The control module assigns a different drive frequency to each bit of binary data. For example, the bit representing "0" has a drive frequency of 200kHz, and the bit representing "1" has a drive frequency of 300kHz. The control module sequentially changes the PWM signal frequency, driving Q1 / Q4 and Q2 / Q3 to alternate conduction. The inverter circuit's output frequency changes with the control bit, thereby modulating the frequency of the alternating magnetic field. The receiver decodes the original data by detecting the frequency of the magnetic field-induced signal.

[0072] (2) Amplitude Shift Keying (ASK) method: All control signal frequencies remain constant; the control module changes the peak value of the output voltage by adjusting the PWM duty cycle or conduction time: a low duty cycle corresponds to a lower amplitude, representing "0"; a high duty cycle corresponds to a higher amplitude, representing "1"; the change in the magnetic field strength output by the transmitting coil can be sampled and identified by the receiving end to achieve amplitude decoding.

[0073] (3) On-off keying (OOK) method: The control module periodically turns off or on the entire set of PWM drive signals: when a certain bit is "0", the drive is temporarily stopped to interrupt the output magnetic field; when it is "1", the drive is normal to keep the magnetic field. The receiving end identifies the data by detecting whether there is a window in the signal (no magnetic field induction).

[0074] The use of MOS tube switch logic circuits has the advantages of simple structure, low cost, and easy integration. It supports multiple modulation methods and is adapted to different communication scenarios and signal quality requirements. All modulation processes are embedded in the drive control, without the need for additional RF encoding devices, achieving compact structure and energy consumption optimization. It can realize contactless, low-interference data transmission, meeting the high safety and high stability requirements of the wireless charging system.

[0075] Furthermore, the receiving end further includes a full-bridge rectifier module and a filter module; The full-bridge rectifier module is connected to the receiving-end coil resonance module to convert the induced current into direct current.

[0076] The receiving end also includes the filtering module connected to the full-bridge rectifier module to filter the direct current and output the filtered current to the battery load for charging.

[0077] In an embodiment of the present application, the receiving end further includes a full-bridge rectifier module and a filter module, which are used to convert the received high-frequency induced electrical energy into stable DC electrical energy and output it to the battery load. The receiving end coil resonance module and the transmitting end coil resonance module transmit energy through spatial magnetic coupling. When the high-frequency alternating magnetic field generated by the transmitting end coil is induced by the receiving end coil, the receiving end coil resonance module outputs a high-frequency AC current. The receiving end coil resonance module is electrically connected to a full-bridge rectifier module, which is used to convert the high-frequency AC induced current into DC current. The rectifier module adopts a bridge structure and completes the unidirectional current by controlling the conduction direction of the diode, eliminating the AC component.

[0078] The filter module, connected to the full-bridge rectifier module, filters the rectified DC power. This filter module typically consists of a parallel filter capacitor and a series filter inductor, suppressing ripple in the rectified current and improving the stability and smoothness of the output voltage. The filtered, stable DC power is then output to the connected battery load to charge the battery. This structure enables stable and reliable power supply for a variety of battery types (such as lead-acid batteries and lithium batteries), enhancing the practicality and compatibility of the entire wireless charging system.

[0079] Furthermore, the transmitting end also includes a serial communication module, which is connected to an external charging pile through the serial communication module for communication, and the external charging pile supplies power to the transmitting end.

[0080] In an embodiment of the present application, the battery load output terminal of the receiving end is connected to the battery pack on a small electric vehicle such as a two-wheeled electric vehicle, and the transmitting end device is connected to the installed charging station master computer through a serial communication module, generally using RS485 / CAN bus to form a network for communication, and the AC-DC module in the charging station master computer supplies power to the connected transmitting end.

[0081] The circuit of the present application also includes a DC input filter module for filtering the input DC voltage to obtain a purer 48V voltage; a transmitter DC / DC+LDO module for stepping down the stable 48V DC voltage to 3.3V; a transmitter RGB module and a receiver RGB module for feedback of the operating status of each module through RGB indicator lights; a rectifier filter module for converting the high-frequency AC power output by the receiver resonant module into low-voltage DC power; and a receiver DC / DC+LDO module for stabilizing the low-voltage DC power output by the rectifier filter module at 3.3V to power the receiver control module or serve as a reference voltage for the sampling module.

[0082] This application completes multiple legitimacy checks before charging starts through "three-stage verification" (wireless communication link verification, encryption key verification, and device identity verification) to ensure that only devices that pass all verifications can obtain energy transmission. The first stage verifies the 2.4GHz two-way link connectivity to eliminate link anomalies or illegal interference; the second stage is based on handshake matching of symmetric encryption keys to prevent key forgery; the third stage transmits the device number through magnetic field encoding and compares it with the preset number to prevent impersonation or unauthorized device access.

[0083] The matching of the coded magnetic field modulated by the transmitter and the sampling and decoding results of the receiver is used to determine whether the magnetic coupling is blocked, thereby accurately detecting foreign objects and issuing an alarm before charging. When any verification stage fails and the number of retries exceeds the limit, the system determines that there may be metal foreign objects causing magnetic field interference, thus realizing non-contact foreign object detection.

[0084] An automatic retry mechanism is built into each verification phase, combining exponential backoff or fixed-delay communication restarts to quickly recover from occasional failures caused by signal distortion or transient interference. Alarms are triggered only after multiple consecutive retry failures, reducing false alarms and improving the system's tolerance to environmental changes.

[0085] The transmitter encodes the unique device number in the high-frequency full-bridge inverter output and modulates the alternating magnetic field through various methods such as frequency keying, amplitude keying or on-off keying. The coil sampling module at the receiving end adopts Schottky diode rectification + multi-stage voltage divider circuit to sample at high speed and accurately restore the number, taking into account low distortion and high signal-to-noise ratio, thereby realizing lossless near-field number transmission and identification.

[0086] Frequency Shift Keying (FSK), Amplitude Shift Keying (ASK), and On-Off Keying (OOK) can be selected as needed to meet the encoding requirements under different distances, interference environments, or power transmission conditions. In strong interference environments, amplitude keying can be switched to enhance frequency offset resistance. In low-power scenarios, OOK can be selected to simplify the driving circuit.

[0087] The modulation and verification processes are all embedded in the inverter drive and sampling links, without the need for additional RF modules or dedicated encoding devices. The sampling and decoding algorithms can be implemented based on existing hardware, avoiding additional power consumption and hardware costs.

[0088] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0089] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0090] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0091] In the embodiments provided in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0092] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0093] If the integrated module / unit is implemented as a software functional unit and sold or used as a standalone product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application can implement all or part of the process steps in the above-mentioned method embodiments by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal, and software distribution medium. It should be noted that the content of the computer-readable medium can be appropriately increased or decreased based on the requirements of legislation and patent practice in a jurisdiction. For example, in some jurisdictions, based on legislation and patent practice, computer-readable media does not include electric carrier signals and telecommunication signals.

[0094] The present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed through a computer program product. When the computer program product is run on a terminal device, the terminal device can implement the steps in the above-mentioned method embodiments when executing.

[0095] The above embodiments are intended only to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the above embodiments or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present application and should be included within the scope of protection of the present application.

Claims

1. A wireless charging circuit for detecting foreign objects, characterized in that: The wireless charging circuit for detecting foreign objects includes a transmitting end and a receiving end; The transmitter includes a transmitter control module, a high-frequency full-bridge inverter module, a transmitter coil resonance module, and a transmitter wireless communication module; The receiving end includes a receiving end coil resonance module, a receiving end control module, a receiving end coil sampling module and a receiving end wireless communication module; The receiving end control module interacts with the transmitting end wireless communication module through the receiving end wireless communication module, and the transmitting end wireless communication module interacts with the transmitting end control module; A device number is preset in the transmitter control module, and the preset device number is a unique device number of the transmitter; The transmitter control module modulates the high-frequency full-bridge inverter module based on the preset device number to generate an alternating magnetic field; The receiving-end coil resonance module is coupled to the transmitting-end coil resonance module, and the receiving-end coil resonance module senses the alternating magnetic field and outputs an AC signal; The transmitting end and the receiving end complete three-stage verification, the three-stage verification including wireless communication verification, encryption key verification and device identity verification; If the verification is successful, the transmitting end control module sends a charging signal to the receiving end control module; The receiving end control module starts the charging process in response to the charging signal; If the verification fails, the transmitting end control module determines that there is a foreign object in the transmitting end coil resonance module and outputs an alarm signal.

2. The wireless charging circuit for detecting foreign objects according to claim 1, characterized in that: The wireless communication verification process includes: The transmitting end wireless communication module establishes a communication connection with the receiving end wireless communication module; In response to the connection status of the transmitting-end wireless communication module and the receiving-end wireless communication module, wireless communication verification is completed.

3. The wireless charging circuit for detecting foreign objects according to claim 1, characterized in that: The encryption key verification process includes: The same encryption key is preset in the transmitting end control module and the receiving end control module; The transmitting end control module and the receiving end control module are matched by exchanging encryption keys to complete encryption key verification.

4. The wireless charging circuit for detecting foreign objects according to claim 1, wherein: The device authentication process includes: The receiving end coil sampling module samples the AC signal and sends the sampling result to the receiving end control module; The receiving end control module obtains the transmitting end device number according to the sampling result, and sends the transmitting end device number to the transmitting end control module; The transmitter control module matches the transmitter device number with the preset device number to complete device identity authentication.

5. The wireless charging circuit for detecting foreign objects according to any one of claims 1 to 4, characterized in that: The wireless communication connection is restarted after verification fails at any stage. When the number of restarts reaches a preset threshold, a foreign object alarm signal is output.

6. The wireless charging circuit for detecting foreign objects according to claim 4, characterized in that: The receiving end coil sampling module includes a diode rectifier circuit and a multi-stage voltage divider circuit; The diode rectifier circuit is used to convert the AC signal output by the receiving end coil resonance module into a positive half-cycle AC signal; The multi-stage voltage divider circuit is used to convert the positive half-cycle AC signal into sampling data suitable for decoding.

7. The wireless charging circuit for detecting foreign objects according to claim 1, characterized in that: The high-frequency full-bridge inverter module includes a MOS tube switch logic circuit; The transmitter control module performs code modulation on the MOS tube switch logic circuit based on the preset device number to generate an alternating magnetic field, and the code modulation method includes at least one of frequency keying, amplitude keying and on-off keying.

8. The wireless charging circuit for detecting foreign objects according to claim 7, characterized in that: When the coded modulation method adopts frequency keying, the frequency of the transmitted signal is changed within a period to distinguish between binary numbers 0 and binary numbers 1.

9. The wireless charging circuit for detecting foreign objects according to claim 7, characterized in that: When the coded modulation method adopts amplitude keying, the amplitude of the transmission power is changed within a period to distinguish binary data, wherein a low amplitude is a binary number 0 and a high amplitude is a binary number 1.

10. The wireless charging circuit for detecting foreign objects according to claim 7, characterized in that: When the coded modulation method adopts on-off keying, binary data is distinguished by interrupting power transmission within a period, wherein the power transmission interruption state is a binary number 0, and the power continuous transmission state is a binary number 1.

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