A wireless charging circuit for detecting foreign objects

Abstract

The application discloses a wireless charging circuit for detecting foreign matters, comprising a transmitting end and a receiving end. The transmitting end generates an alternating magnetic field through a high-frequency full-bridge inverter module and performs encoding modulation based on a unique preset device number. The receiving end couples to the magnetic field and samples and decodes to realize three-stage verification with the transmitting end, including wireless communication verification, encryption key verification and device identity verification. A control module decides whether to start charging or output a metal foreign matter alarm signal according to the verification result. The scheme completes a layered security verification process before charging, ensures the safety of wireless energy transmission and the accurate identification ability of the system to foreign matters, improves the stability and reliability of the wireless charging system, avoids abnormal problems such as fire caused by foreign matter heating during charging, and is suitable for wireless power supply application scenarios supporting a security authentication mechanism.

Description

Technical Field

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

[0002] In recent years, with the development of wireless power transfer technology, wireless charging has been widely used in consumer electronics, medical devices, electric vehicles, and other fields. Wireless charging systems based on electromagnetic induction or magnetic resonance coupling typically include a transmitter and a receiver, enabling contactless energy transfer in space. However, during wireless charging, the presence of metallic foreign objects in the charging area can lead to energy loss, electromagnetic interference, and even overheating and burnout, posing safety hazards. Therefore, improving the accuracy and response capability of metallic foreign object detection in wireless charging systems has become a key focus of current research and industry attention.

[0003] In existing technologies, most foreign object detection methods rely on temperature sensors, current change monitoring, and other methods for judgment. However, these methods have drawbacks such as response delay, high false judgment rate, or can only detect foreign objects after charging has started, making 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 from disguised 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 determine the legitimacy of the device and the safety of the environment before charging begins. Summary of the Invention

[0005] This application provides a wireless charging circuit for detecting foreign objects, in order to solve the common problem in existing wireless charging systems where low detection accuracy of foreign objects leads to overheating and fire during charging.

[0006] In a first aspect, this application provides a wireless charging circuit for detecting foreign objects, the wireless charging circuit for detecting foreign objects including a transmitter and a receiver;

[0007] The transmitter includes a transmitter control module, a high-frequency full-bridge inverter module, a transmitter coil resonant module, and a transmitter wireless communication module;

[0008] The receiving end includes a receiving end coil resonant module, a receiving end control module, a receiving end coil sampling module, and a receiving end wireless communication module;

[0009] 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.

[0010] The transmitter control module has a preset device number, which is a unique device number for the transmitter.

[0011] The transmitter control module modulates the high-frequency full-bridge inverter module based on the preset device number to generate an alternating magnetic field;

[0012] The receiving coil resonant module is coupled to the transmitting coil resonant module, and the receiving coil resonant module senses the alternating magnetic field and outputs an AC signal;

[0013] The transmitting end and the receiving end complete a three-stage verification, which includes wireless communication verification, encryption key verification and device authentication.

[0014] If the verification is successful, the transmitting end control module sends a charging signal to the receiving end control module;

[0015] The receiving end control module initiates the charging process in response to the charging signal;

[0016] If the verification fails, the transmitter control module determines that there is a foreign object in the transmitter coil resonant module and outputs an alarm signal.

[0017] Optionally, the wireless communication verification process includes:

[0018] The transmitting end wireless communication module establishes a communication connection with the receiving end wireless communication module;

[0019] The wireless communication verification is completed in response to the connection status between the transmitting end wireless communication module and the receiving end wireless communication module.

[0020] Optionally, the encryption key verification process includes:

[0021] The transmitting end control module and the receiving end control module are pre-set with the same encryption key;

[0022] The transmitting end control module and the receiving end control module exchange encryption keys to match and complete the encryption key verification.

[0023] Optionally, the device authentication process includes:

[0024] The receiving end coil sampling module samples the AC signal and sends the sampling result to the receiving end control module;

[0025] The receiving end control module obtains the transmitting end device number based on the sampling result, and sends the transmitting end device number to the transmitting end control module;

[0026] The transmitter control module matches the transmitter device number with the preset device number to complete device authentication.

[0027] Optionally, the feature is that the wireless communication connection is restarted after verification fails at any stage, and a metal foreign object alarm signal is output when the number of restarts reaches a preset threshold.

[0028] Optionally, the receiving coil sampling module includes a diode rectifier circuit and a multi-stage voltage divider circuit;

[0029] The diode rectifier circuit is used to convert the AC signal output by the receiving coil resonant module into a positive half-cycle AC signal.

[0030] The multi-stage voltage divider circuit is used to convert the positive half-cycle AC signal into sampled data suitable for decoding.

[0031] Optionally, the high-frequency full-bridge inverter module includes a MOSFET switching logic circuit;

[0032] The transmitter control module encodes and modulates the MOS transistor switching logic circuit based on the preset device number to generate an alternating magnetic field. The encoding and modulation method includes at least one of frequency keying, amplitude keying, and on / off keying.

[0033] Optionally, when the encoding and modulation method employs frequency keying, the frequency of the transmitted signal is changed within a period to distinguish between binary 0 and binary 1.

[0034] Optionally, when the encoding and modulation method uses amplitude keying, binary data is distinguished by changing the amplitude of the transmission power within a period, where low amplitude represents binary 0 and high amplitude represents binary 1.

[0035] Optionally, the encoding and modulation method employs on / off keying, which distinguishes binary data by interrupting power transmission within a period, wherein the power transmission interruption state is binary number 0, and the power transmission continuous state is binary number 1.

[0036] The technical solutions provided in this application have the following advantages compared with the prior art:

[0037] (1) Improve the security of wireless charging system: By introducing a three-stage authentication mechanism (wireless communication authentication, encryption key authentication, and device authentication), the legality of the device is confirmed before charging, which effectively prevents unauthorized access and impersonation.

[0038] (2) Enhance the detection capability of metal foreign objects: When the verification failure reaches the threshold of the number of retry times, an alarm signal is output to identify the interference of foreign objects before charging starts, effectively avoiding safety hazards such as overheating and energy loss caused by foreign objects.

[0039] (3) Realize contactless identity data transmission and recognition: The transmitter modulates the device number into an 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.

[0040] (4) Supports multiple modulation methods to improve signal compatibility and decoding accuracy: The encoding modulation method supports at least one of frequency keying, amplitude keying and on / off keying to adapt to different transmission environments and improve system robustness and decoding recognition rate.

[0041] (5) It has an adaptive retry and alarm mechanism to improve system stability: When a certain 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.

[0042] (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.

[0043] (7) Clear structural modules facilitate integration and application promotion: The system takes the control module as the core and combines wireless communication, encoding and modulation, magnetic field transmission and sampling decoding modules, which facilitates the collaborative development of software and hardware and the subsequent engineering implementation of products. Attached Figure Description

[0044] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0047] Figure 1 A schematic diagram of the module structure of a wireless charging circuit for detecting foreign objects provided in an embodiment of this application;

[0048] Figure 2A schematic diagram of the transmitter in the wireless charging circuit for detecting foreign objects provided in an embodiment of this application;

[0049] Figure 3 This is a schematic diagram of the receiver in the wireless charging circuit for detecting foreign objects provided in an embodiment of this application. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0052] like Figure 1 As shown, Figure 1 This is a schematic diagram of the module structure of a wireless charging circuit for detecting foreign objects, provided in an embodiment of this application.

[0053] The following describes the corresponding modules. Figures 2-3 The middle position can be referenced Figure 1 The label description, such as Figure 1 As shown, the wireless charging circuit of this application includes a transmitter 100 and a receiver 200. 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 resonant module 105, a serial communication module 106, a DC input filtering module 107, a transmitter DC / DC+LDO module 108, and a transmitter RGB module 109.

[0054] The receiver 200 includes a receiver control module 201, a receiver coil resonant module 202, a receiver coil sampling module 203, a receiver wireless communication module 204, a full-bridge rectifier module 205, a filter module 206, a rectifier and filter module 207, a receiver DC / DC+LDO module 208, a receiver RGB module 209, a battery load 210, a receiver serial communication module 211, and a receiver coil sampling module 212.

[0055] 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 power conversion and outputting excitation current based on the control signals output by the control module; a transmitter wireless communication module for information exchange with the receiver wireless communication module; a transmitter sampling module for acquiring electrical parameters such as the transmitter's input voltage, input current, and voltage at the transmitter coil coupling port; and a transmitter coil resonant module connected to the output of the high-frequency full-bridge inverter module for generating an alternating magnetic field based on the excitation current.

[0056] The receiving end includes: a receiving end control module for receiving control commands, processing receiving end data, and storing preset battery configuration parameters; a receiving end wireless communication module for transmitting the battery configuration parameters and sampled data from the receiving end control module to the transmitting end wireless communication module to achieve information interaction; 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 resonant module, magnetically coupled to the transmitting end coil resonant module, for receiving alternating magnetic fields and inducing high-frequency alternating current.

[0057] In actual operation, the receiving end coil sampling module collects parameters such as receiving end charging current, battery voltage and temperature in real time. The receiving end control module sends the above sampling parameters and the preset battery configuration parameters stored in its internal storage 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.

[0058] The transmitter sampling module collects the transmitter's operating parameters, including input voltage, input current, and the coupling port voltage of the transmitter coil resonant module, and transmits the sampled data to the transmitter control module.

[0059] The transmitter control module analyzes the current charging stage and load demand based on the received preset battery configuration parameters, receiver parameters, and transmitter parameters, and outputs control signals to regulate the switching state of each MOSFET in the high-frequency full-bridge inverter module.

[0060] After receiving the aforementioned control signals, the high-frequency full-bridge inverter module outputs a forward or reverse excitation current to the transmitting coil resonant module according to the control logic of the first and second control signals, thereby forming an alternating magnetic field with a specific frequency and power. This alternating magnetic field is transmitted to the receiving coil resonant module through spatial magnetic coupling, where the receiving coil induces high-frequency alternating current to provide power for subsequent rectification, filtering, and charging processes.

[0061] 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.

[0062] The transmitter control module has a preset device number, which is a unique device number for the transmitter.

[0063] The transmitter control module modulates the high-frequency full-bridge inverter module based on the preset device number to generate an alternating magnetic field;

[0064] The receiving coil resonant module is coupled to the transmitting coil resonant module, and the receiving coil resonant module senses the alternating magnetic field and outputs an AC signal;

[0065] The transmitting end and the receiving end complete a three-stage verification, which includes wireless communication verification, encryption key verification and device authentication.

[0066] If the verification is successful, the transmitting end control module sends a charging signal to the receiving end control module;

[0067] The receiving end control module initiates the charging process in response to the charging signal;

[0068] If the verification fails, the transmitter control module determines that there is a foreign object in the transmitter coil resonant module and outputs an alarm signal.

[0069] In this embodiment, the transmitting end control module presets a unique device number to identify the transmitting end. When the receiving end initiates the verification process, the receiving end control module establishes a connection with the transmitting end wireless communication module through the receiving end wireless communication module and interacts with the transmitting end control module. The transmitting end wireless communication module is responsible for forwarding the received communication requests and verification information to the transmitting end control module.

[0070] During the authentication phase, the transmitter control module modulates and controls the high-frequency full-bridge inverter module based on a preset device number. For example, the transmitter control module can change the on-time of the MOSFET switches in the inverter module through a PWM control signal, and use methods such as frequency keying (FSK), amplitude keying (ASK), or on / off keying (OOK) to encode and modulate the device number into the alternating magnetic field.

[0071] The transmitting coil resonant module generates an alternating magnetic field carrying the device number under modulation drive. The receiving coil resonant module is spatially coupled to this magnetic field and outputs an AC signal. This AC signal is rectified and voltage-divided by the receiving coil sampling module and then sent to the receiving control module for decoding. The decoded device number is then returned to the transmitting end via the receiving wireless communication module for matching.

[0072] The system completes a three-stage verification process sequentially, including: wireless communication verification: ensuring a communication link is established between the transmitter and receiver; encryption key verification: handshake matching based on the symmetric encryption keys pre-stored by both parties; and device authentication: completing the transmission, sampling, decoding, and comparison of device IDs.

[0073] When all three stages of verification pass, the transmitting control module sends a charging start signal to the receiving control module. The receiving control module responds to this signal, turning on the receiving power circuit and initiating the charging process. If any stage of verification fails, the transmitting control module determines that there may be an interference source or metallic foreign object, outputs an alarm signal, and stops charging.

[0074] Furthermore, the wireless communication verification process includes:

[0075] The transmitting end wireless communication module establishes a communication connection with the receiving end wireless communication module;

[0076] The wireless communication verification is completed in response to the connection status between the transmitting end wireless communication module and the receiving end wireless communication module.

[0077] In this embodiment of the application, after the receiving end is powered on, the receiving end wireless communication module initiates a communication request via broadcast. The transmitting end wireless module listens to the request and responds, completing the 2.4 GHz link connection. The communication status is confirmed by the control modules of both parties as the first stage of verification.

[0078] 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, 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 within the coupled magnetic field of the transmitter coil, the receiver coil resonant module 202 induces an alternating magnetic field and outputs an AC signal. This signal is converted to DC by the rectifier and filter module 207, and then regulated to 3.3V by the receiver DC / DC+LDO module 208 to power and start the receiver control module 201 and the receiver wireless communication module 204.

[0079] Specifically, the wireless communication verification process includes:

[0080] The transmitter control module 101 activates the wireless communication module 103 to initiate an active scan in the 2.4 GHz band, covering all available channels to detect broadcast signals from the receiver.

[0081] The receiving wireless communication module 204 broadcasts a broadcast signal containing a device type identifier immediately after being powered on;

[0082] After capturing the broadcast signal, the transmitting wireless communication module 103 sends a connection request;

[0083] Both parties establish a link through a handshake protocol, exchange MAC addresses and communication parameters, and complete a three-way handshake;

[0084] 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.

[0085] If the data packet loss rate is greater than or equal to the set threshold, the connection status is marked as failed. The transmitter control module 101 responds to the failure status and automatically restarts the wireless communication connection after failure. If the number of restarts reaches the preset threshold and still fails, it is determined that the verification has failed, outputs a metal foreign object alarm signal, and outputs a flashing signal through the RGB light indicator module 209. At the same time, it reports to the main control host computer that the wireless communication verification has failed and that there is suspected metal foreign object interference.

[0086] In one possible implementation, the receiver control module 201 records the connection timestamp and the transmitter MAC address for subsequent interactions such as device authentication.

[0087] Furthermore, the encryption key verification process includes:

[0088] The transmitting end control module and the receiving end control module are pre-set with the same encryption key;

[0089] The transmitting end control module and the receiving end control module exchange encryption keys to match and complete the encryption key verification.

[0090] In this embodiment, each of the two control modules pre-stores a symmetric encryption key (such as a 128-bit AES key). After establishing communication, they exchange random numbers and encryption digests through a handshake protocol to verify key consistency, serving as the second-stage encryption key verification.

[0091] like Figure 2 and Figure 3 As shown, during the equipment manufacturing stage, the same 128-bit AES encryption key is programmed into the transmitter control module 101 and receiver control module 201 of each wireless charging system. The same key pair is simultaneously written to the paired transmitter and receiver using production line fixtures to ensure unique matching.

[0092] Specifically, the encryption key verification process includes:

[0093] During the manufacturing process, the transmitting and receiving control modules each have a pre-set set of identical symmetric encryption keys, such as a fixed-length digital sequence. These keys are stored in the protected storage areas of both devices and are not transmitted in plaintext.

[0094] After receiving feedback confirming successful communication verification, the transmitter control module randomly generates a set of random numbers as verification data. The transmitter control module encrypts this random number using a locally preset encryption key and transmits the encrypted ciphertext to the receiver via the transmitter wireless communication module.

[0095] After receiving the encrypted ciphertext, the receiving end control module decrypts it using its own preset key to obtain the decryption result. Subsequently, the transmitting end resends the original random number in plaintext to the receiving end, and the receiving end compares the decryption result with the plaintext data to see if they match.

[0096] If the decryption result at the receiving end matches the plaintext random number, it indicates that the transmitting and receiving ends are using the same encryption key, and the match is successful. At this time, the receiving end control module sends a "key verification passed" message back to the transmitting end through the receiving end wireless communication module.

[0097] If the decryption results are inconsistent, or if the key verification process is not completed within the set time, the control module determines that the encryption keys are inconsistent and considers the verification to have failed. The transmitting end 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.

[0098] Furthermore, the device authentication process includes:

[0099] The receiving end coil sampling module samples the AC signal and sends the sampling result to the receiving end control module;

[0100] The receiving end control module obtains the transmitting end device number based on the sampling result, and sends the transmitting end device number to the transmitting end control module;

[0101] The transmitter control module matches the transmitter device number with the preset device number to complete device authentication.

[0102] The receiving coil sampling module includes a diode rectifier circuit and a multi-stage voltage divider circuit;

[0103] The diode rectifier circuit is used to convert the AC signal output by the receiving coil resonant module into a positive half-cycle AC signal.

[0104] The multi-stage voltage divider circuit is used to convert the positive half-cycle AC signal into sampled data suitable for decoding.

[0105] After completing wireless communication verification and encryption key verification, the system proceeds to the third stage, device authentication, which is used to confirm whether the transmitter is a pre-authorized device.

[0106] The transmitter control module modulates and controls the high-frequency full-bridge inverter module based on a preset unique device number. This control modulates the device number into a modulated signal by changing the on-time of the switching transistors in the inverter circuit, using an encoding method (such as frequency keying, amplitude keying, or on / off keying). The modulated signal is radiated into space as an alternating magnetic field through the transmitter coil resonant module.

[0107] The receiving coil resonant module forms a spatial coupling with the transmitting end, inducing 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 voltage divider circuit to compress the signal to a voltage range suitable for analog-to-digital converter sampling; and the receiving control module performing high-speed sampling of the voltage-divided signal to obtain a voltage sequence reflecting the modulation content of the device number.

[0108] The receiver control module performs digital processing on the sampling results, and identifies and decodes 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 and assigns them to different binary bits; if amplitude keying is used, it identifies 0 or 1 by recognizing changes in voltage amplitude; if on / off keying is used, it determines the data bits by detecting the presence or absence of a signal.

[0109] After decoding, the receiving control module recovers the transmitter's device ID data. The decoded transmitter device ID is then sent from the receiving wireless communication module to the transmitting wireless communication module. Upon receiving this ID, the transmitting control module compares it with its locally preset device IDs. If they match perfectly, the verification is considered successful; otherwise, the verification is considered a failure.

[0110] If the verification is successful, the transmitting end control module sends a "start charging" command to the receiving end, and the receiving end control module turns on the subsequent power circuit and enters the normal charging mode accordingly. If the verification fails, and multiple failures still fail to match, the transmitting end control module can trigger the alarm logic to determine that there may be foreign object interference and stop the energy transmission.

[0111] In this embodiment of the application, the wireless charging system is designed for security and robustness. If a communication interruption, decryption error, or identity mismatch occurs during any stage of the authentication process between the transmitter and receiver, the system will automatically execute a retry mechanism. If the retry fails after multiple attempts, the system will output a foreign object alarm signal by flashing the RGB light indicator module 209 to prompt the user or the upper-level system to intervene.

[0112] Furthermore, the high-frequency full-bridge inverter module includes a MOSFET switching logic circuit;

[0113] The transmitter control module encodes and modulates the MOS transistor switching logic circuit based on the preset device number to generate an alternating magnetic field. The encoding and modulation method includes at least one of frequency keying, amplitude keying, and on / off keying.

[0114] When the encoding and modulation method uses frequency keying, the frequency of the transmitted signal is changed within a period to distinguish between binary 0 and binary 1.

[0115] When the encoding and modulation method uses amplitude keying, binary data is distinguished by changing the amplitude of the transmission power within a period, where low amplitude represents binary 0 and high amplitude represents binary 1.

[0116] The encoding and modulation method employs on / off keying, which distinguishes binary data by interrupting power transmission within a cycle. The interrupted power transmission state is represented by binary number 0, while the continuous power transmission state is represented by binary number 1.

[0117] In this embodiment, the high-frequency full-bridge inverter module at the transmitting end converts the modulation signal output by the control module into alternating current to drive the transmitting end coil resonant module to generate an alternating magnetic field. This module is not only responsible for power conversion but also undertakes encoding and modulation functions, making it a key component in the system for realizing device number modulation transmission.

[0118] The high-frequency full-bridge inverter module adopts a full-bridge topology, consisting of four N-channel power MOSFETs forming a bridge switching unit, denoted as Q1, Q2, Q3, and Q4. The output is connected to an inductor L1 and a resonant capacitor C1 in series, forming the transmitter coil resonant module.

[0119] The transmitter control module internally stores a unique device number, converts it into a binary bit stream (e.g., 64 bits), and uses this stream for modulation via the switching logic of the MOSFETs. The control strategy varies depending on the modulation method:

[0120] (a) Frequency Keying (FSK) method: The control module assigns a different driving frequency to each bit of binary data. For example, the driving frequency of the bit representing "0" is 200kHz, and the driving frequency of the bit representing "1" is 300kHz; the control module changes the frequency of the PWM signal in sequence, driving Q1 / Q4 and Q2 / Q3 to conduct alternately; the output frequency of the inverter circuit changes with the control bit, thereby modulating the frequency of the alternating magnetic field; the receiving end decodes the original data by detecting the frequency of the magnetic field-induced signal.

[0121] (ii) Amplitude Shift Keying (ASK) mode: 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.

[0122] (III) On / Off Key Control (OOK) Mode: The control module periodically turns the entire PWM drive signal off or on: when a certain bit is "0", the drive is temporarily stopped, causing the output magnetic field to be interrupted; when it is "1", the drive is normal, causing the magnetic field to continue to exist; the receiving end identifies the data by detecting whether there is a gap in the signal (no magnetic field induction).

[0123] Using MOS transistor switching logic circuits has the advantages of simple structure, low cost and easy integration. It supports multiple modulation methods, adapts to different communication scenarios and signal quality requirements. All modulation processes are embedded in the drive control, eliminating the need for additional RF coding devices. This achieves a compact structure and optimized energy consumption, enabling contactless, low-interference data transmission and meeting the high safety and stability requirements of wireless charging systems.

[0124] Furthermore, the receiving end also includes a full-bridge rectifier module and a filtering module;

[0125] The full-bridge rectifier module is connected to the receiving coil resonant module to convert the induced current into direct current.

[0126] The receiving end also includes the filtering module connected to the full-bridge rectifier module, which filters the DC power and outputs the filtered current to the battery load for charging.

[0127] In this embodiment, the receiving end further includes a full-bridge rectifier module and a filter module, 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 resonant module and the transmitting end coil resonant module transmit energy via 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 resonant module outputs a high-frequency alternating current. The receiving end coil resonant module is electrically connected to the full-bridge rectifier module, which converts the high-frequency alternating induced current into DC current. This rectifier module adopts a bridge structure, and the current is unidirectionally controlled by diode conduction direction control, eliminating the alternating current component.

[0128] The filtering module is connected to the full-bridge rectifier module and is used to filter the rectified DC power. The filtering module typically includes parallel filter capacitors and series filter inductors to suppress ripple components in the rectified current, improving the stability and smoothness of the output voltage. The filtered, stable DC power is output to the connected battery load to charge the battery. This structure can provide stable and reliable power to various types of batteries (such as lead-acid batteries and lithium batteries), which helps improve the practicality and compatibility of the entire wireless charging system.

[0129] Furthermore, the transmitter also includes a serial communication module, which is connected to an external charging pile for communication, and the external charging pile supplies power to the transmitter.

[0130] In this embodiment, the receiving end battery load output is connected to the battery pack on small electric vehicles such as two-wheeled electric vehicles. The transmitting end device communicates with the main control unit of the charging station through a serial communication module, generally using RS485 / CAN bus networking. The AC-DC module in the main control unit of the charging station supplies power to the connected transmitting end.

[0131] The circuit of this application also includes a DC input filter module for filtering the input DC voltage to obtain a cleaner 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 providing feedback on the operating status of each module through RGB indicator lights; a rectification and filtering module for converting the high-frequency AC power output from the receiver resonant module into low-voltage DC power; and a receiver DC / DC+LDO module for stabilizing the low-voltage DC power output from the rectification and filtering module at 3.3V to power the receiver control module or as a reference voltage for the sampling module.

[0132] This application employs a "three-stage verification" process (wireless communication link verification, encryption key verification, and device authentication) to complete multiple legality checks before charging begins, ensuring that only devices that pass all verifications can receive energy transmission. The first stage verifies the connectivity of the 2.4GHz bidirectional link to eliminate link anomalies or illegal interference. The second stage uses a handshake matching based on symmetric encryption keys to prevent key forgery. The third stage transmits the device number via magnetic field encoding and compares it with a preset number to prevent impersonation or unauthorized devices from accessing the device.

[0133] By matching the encoded magnetic field modulated at the transmitter with the sampled and decoded results at the receiver, the system determines whether the magnetic coupling is obstructed, 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 a metallic foreign object causing magnetic field interference, thus achieving non-contact foreign object detection.

[0134] An automatic retry mechanism is built into each verification stage. Combined with exponential backoff or fixed-delay restart communication, verification can be quickly recovered when occasional signal distortion or transient interference causes a brief failure. Alarms are only triggered after multiple consecutive failed retries, reducing false alarms and improving the system's tolerance to environmental changes.

[0135] 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 receiver's coil sampling module adopts Schottky diode rectification + multi-stage voltage divider circuit to sample at high speed and accurately recover the number, taking into account both low distortion and high signal-to-noise ratio, thereby achieving lossless near-field number transmission and identification.

[0136] 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 Shift Keying can be switched to enhance anti-frequency deviation capability; in low-power scenarios, OOK can be selected to simplify the driving circuit.

[0137] The modulation and verification process is entirely embedded in the inverter drive and sampling stages, requiring no 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.

[0138] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to 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 embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0139] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0140] Those skilled in the art will recognize that the units and algorithm steps of the various examples 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 implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art 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.

[0141] 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 instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling or direct coupling or communication connection may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0142] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0143] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0144] The implementation of all or part of the processes in the methods of the above embodiments can also be accomplished by a computer program product. When the computer program product is run on a terminal device, the terminal device can implement the steps in the various method embodiments described above.

[0145] The embodiments described above are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A wireless charging circuit for detecting a foreign object, characterized by, The foreign matter detection wireless charging circuit comprises a transmitting end and a receiving end; The transmitting end comprises a transmitting end control module, a high-frequency full-bridge inverter module, a transmitting end coil resonance module, and a transmitting end wireless communication module; The receiving end comprises 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 and the transmitting end control module; The transmitting end control module is preconfigured with a preset device number, which is a unique device number of the transmitting end; The transmitting end 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 with the transmitting end coil resonance module, and the receiving end coil resonance module induces the alternating magnetic field and outputs an alternating current signal; The transmitting end and the receiving end complete three-stage verification, which comprises 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 a charging process in response to the charging signal; If the verification fails, the transmitting end control module determines that there is a foreign matter in the transmitting end coil resonance module and outputs an alarm signal.

2. The wireless charging circuit for detecting a foreign object according to claim 1, wherein The wireless communication verification process comprises: The transmitting end wireless communication module and the receiving end wireless communication module establish a communication connection; In response to the connection state of the transmitting end wireless communication module and the receiving end wireless communication module, wireless communication verification is completed.

3. The wireless charging circuit of claim 1, wherein, The encryption key verification process comprises: The transmitting end control module and the receiving end control module are preconfigured with the same encryption key; The transmitting end control module and the receiving end control module are matched by exchanging the encryption key to complete the encryption key verification.

4. The wireless charging circuit of claim 1, wherein, The device identity verification process comprises: The receiving end coil sampling module samples the alternating current 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 transmitting end control module matches the transmitting end device number and the preset device number to complete the device identity verification.

5. The wireless charging circuit for detecting a foreign object according to any one of claims 1 to 4, characterized by, After any stage verification fails, restart the wireless communication connection, and when the number of restarts reaches a preset threshold, output a foreign matter alarm signal.

6. The wireless charging circuit of claim 4, wherein, The receiving end coil sampling module comprises a diode rectifier circuit and a multi-stage voltage dividing circuit; The diode rectifier circuit is used to convert the alternating current signal output by the receiving end coil resonance module into a positive half-cycle alternating current signal; The multi-stage voltage dividing circuit is used to convert the positive half-cycle alternating current signal into sampling data suitable for decoding.

7. The wireless charging circuit of claim 1, wherein, The high-frequency full-bridge inverter module comprises a MOS tube switch logic circuit; The transmitting end control module encodes and modulates the MOS switch logic circuit based on the preset device number to generate an alternating magnetic field, and the encoding and modulation mode includes at least one of frequency keying, amplitude keying and on-off keying.

8. The wireless charging circuit of claim 7, wherein, When the encoding and modulation mode adopts frequency keying, the frequency of the transmission signal is changed in a period to distinguish binary number 0 and binary number 1.

9. The wireless charging circuit of claim 7, wherein, When the encoding and modulation mode adopts amplitude keying, the amplitude of the transmission power is changed in a period to distinguish binary data, wherein low amplitude is binary number 0 and high amplitude is binary number 1.

10. The wireless charging circuit of claim 7, wherein, When the encoding and modulation mode adopts on-off keying, the power transmission is interrupted in a period to distinguish binary data, wherein the power transmission interruption state is binary number 0 and the power continuous transmission state is binary number 1.

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