Foreign matter detection method and system, storage medium and program product

Abstract

The embodiment of the invention provides a foreign matter detection method and system, a storage medium and a program product, and relates to the technical field of wireless charging. The method comprises the following steps: pairing and combining every two detection coils to form a detection coil pairing group, deploying the detection coil pairing group in a working range of a transmitting coil and a receiving coil, sending an excitation signal to each resonant circuit, and activating two resonant circuits of the same detection coil pairing group at the same time; acquiring voltage state data of each activated resonant circuit on a sampling point, and respectively determining deviation state data of each detection coil pairing group according to state deviation between two pieces of voltage state data of the same detection coil pairing group at the same moment; and obtaining foreign matter detection data according to the voltage state data and the deviation state data. Under the condition of not increasing extra hardware deployment and maintenance cost, the judgment of foreign matter detection from various different dimensions can be realized, and the accuracy of foreign matter detection can be improved while the cost is considered.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of wireless charging technology, and particularly to a foreign object detection method, system, storage medium, and program product. Background Technology

[0002] Wireless charging, as a more convenient and efficient charging method, is widely used for charging electrical devices due to its advantages such as convenience, intelligence, safety, aesthetics, and environmental friendliness. Wireless charging systems generally employ electromagnetic induction, meaning a transmitting coil is placed on the ground side and a receiving coil is placed on the device side. Energy is transmitted through magnetic field coupling between the transmitting and receiving coils. To further ensure the normal operation and safety of wireless charging systems, foreign object detection is typically performed during charging. Related technologies employ both direct and indirect detection methods. However, direct detection relies on external detection equipment and has high maintenance costs. While indirect detection has lower deployment and maintenance costs, its accuracy is lower under high-power charging conditions. Therefore, balancing cost and accuracy in foreign object detection is a pressing technical challenge. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0004] This application provides a foreign object detection method, system, storage medium, and program product that can improve the accuracy of foreign object detection while taking cost into account.

[0005] In a first aspect, according to the foreign object detection method of the wireless charging system according to the embodiments of this application, the wireless charging system includes a detection coil matrix, the detection coil matrix is ​​composed of multiple pairs of paired detection coil arrays, the first end of each detection coil is connected to a capacitor, the second end of the detection coil is grounded to form a resonant circuit, and a sampling point is provided at the first end of the capacitor away from the detection coil, the method including:

[0006] An excitation signal is sent to each of the resonant circuits, causing two of the resonant circuits in the same detection coil pairing group to be activated simultaneously;

[0007] The voltage state data of each activated resonant circuit at the sampling point is obtained, wherein the voltage state data characterizes the voltage change relationship between the corresponding sampling point and time.

[0008] Based on the state deviation between the two voltage state data of the same detection coil pairing group at the same time, the deviation state data of each detection coil pairing group is determined respectively.

[0009] Foreign object detection data is obtained based on the voltage state data and the deviation state data.

[0010] Secondly, the wireless charging system according to embodiments of this application includes:

[0011] The detection coil matrix consists of multiple pairs of paired detection coil arrays. Each detection coil has a capacitor connected to its first end and a grounded second end to form a resonant circuit. A sampling point is provided at the capacitor's first end away from the detection coil.

[0012] The acquisition circuit module is used to send excitation signals to each of the resonant circuits and simultaneously activate two of the resonant circuits in the same detection coil pairing group; to perform voltage state detection on each activated resonant circuit and obtain voltage state data of each resonant circuit at the sampling point; wherein the voltage state data characterizes the voltage change relationship between the corresponding sampling point and time.

[0013] The processing module is used to determine the deviation state data of each pair of detection coils based on the state deviation between the two voltage state data of the same pair of detection coils at the same time; and to obtain foreign object detection data based on the voltage state data and the deviation state data.

[0014] Thirdly, according to embodiments of this application, a computer-readable storage medium stores computer-executable instructions for use in the foreign object detection method of any of the wireless charging systems described in the first aspect.

[0015] Fourthly, a computer program product according to an embodiment of this application includes a computer program or computer instructions stored in a computer-readable storage medium. A processor of a control device reads the computer program or computer instructions from the computer-readable storage medium, and the processor executes the computer program or computer instructions to cause the control device to perform a foreign object detection method for a wireless charging system as described in any of the first aspects.

[0016] The embodiments of this application, by pairing detection coils into pairs to form a detection coil pairing group and deploying it within the working range of the transmitting and receiving coils, and acquiring the deviation state data of the same detection coil pairing group at the same time, can determine the state deviation between the two detection coils within the same detection coil pairing group. Simultaneously, by combining the voltage state data of each detection coil, it is possible to achieve foreign object detection from multiple different dimensions without increasing additional hardware deployment and maintenance costs. Therefore, compared with related technologies, the embodiments of this application can improve the accuracy of foreign object detection while considering cost. Attached Figure Description

[0017] Figure 1 A schematic diagram of the wireless charging system provided in this application;

[0018] Figure 2 A schematic diagram showing the positions of the transmitting coil, receiving coil, and detection coil matrix in one embodiment of the wireless charging system provided in this application;

[0019] Figure 3 An equivalent circuit diagram of a resonant circuit in one embodiment of the wireless charging system provided in this application;

[0020] Figure 4 A schematic diagram of the circuit structure for amplitude and phase detection in one embodiment of the wireless charging system provided in this application;

[0021] Figure 5 A schematic diagram of the circuit structure of the acquisition circuit module for time-division acquisition in one embodiment of the wireless charging system provided in this application;

[0022] Figure 6 A schematic diagram of the circuit structure providing the excitation signal in the acquisition circuit module of one embodiment of the wireless charging system provided in this application;

[0023] Figure 7 A flowchart illustrating the foreign object detection method for the wireless charging system provided in this application;

[0024] Figure 8 A flowchart illustrating an embodiment of the foreign object detection method for the wireless charging system provided in this application;

[0025] Figure 9 A flowchart illustrating another embodiment of the foreign object detection method for the wireless charging system provided in this application;

[0026] Figure 10 A schematic diagram of the device hardware structure corresponding to the device management method provided in this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0028] It should be noted that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0029] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0030] The following is an explanation of the terms used in the embodiments of this application:

[0031] Foreign Object Detection (FOD) is a technology used during wireless charging to prevent the system from overheating due to unexpected objects (especially conductors such as metal).

[0032] Living Object Detection (LOD) is a technology used during wireless charging to prevent living objects such as humans or animals from entering the charging protection zone and potentially suffering health damage due to strong radiation.

[0033] Position detection, or PD for short, is used to enable close-range vehicle alignment guidance and yaw angle recognition.

[0034] Field-Programmable Gate Array (FPGA) is a product developed based on programmable devices such as Programmable Array Logic (PAL) and General Purpose Array Logic (GAL). It is a semi-custom circuit in the field of application-specific integrated circuits (ASICs), addressing the shortcomings of custom circuits.

[0035] An analog-to-digital converter (ADC) is an electronic component that converts analog signals into digital signals. A typical ADC converts an input voltage signal into an output digital signal.

[0036] Direct Digital Synthesizer (DDC) is a digital electronic method that generates arbitrary waveforms and frequencies from a single (or mixed) frequency source. It is commonly used in function generators, mixers, modulators, and sound synthesizers.

[0037] Serial Peripheral Interface, or SPI for short, is primarily used in EEPROM, FLASH, real-time clocks, AD converters, and between digital signal processors and digital signal decoders. It is a high-speed, full-duplex, synchronous serial communication bus.

[0038] A printed circuit board (PCB) is a type of electronic component manufactured using electronic printing techniques. It is an important electronic component, serving as the support structure for electronic parts and providing electrical connections between them.

[0039] Low Voltage Differential Signaling (LVDS) is a differential signaling technology characterized by low power consumption, low bit error rate, low crosstalk, and low radiation. It can achieve transmission speeds of over 155 Mbps. Its core technology is to use extremely low voltage swing for high-speed differential data transmission, enabling point-to-point or point-to-multipoint connections.

[0040] A microcontroller unit, or MCU for short, is a chip-level computer that integrates a central processing unit with a reduced frequency and specifications, along with peripheral interfaces such as memory, counters, USB, A / D converters, UART, PLC, DMA, and even LCD driver circuitry, onto a single chip.

[0041] Digital Signal Processing (DSP) refers to the technology of implementing digital signal processing. DSP chips are chips that can implement digital signal processing techniques. Internally, they employ a Harvard architecture that separates program and data processing, have dedicated hardware multipliers, widely utilize pipelined operation, and provide special DSP instructions, enabling the rapid implementation of various digital signal processing algorithms.

[0042] With increasing global concern about climate change, electricity is being widely used as a new energy source. Wireless charging, as a more convenient and efficient charging method, is widely used for charging electrical equipment due to its advantages such as convenience, intelligence, safety, aesthetics, and environmental friendliness. Taking electric vehicles as an example, with the rapid advancements in technologies such as autonomous driving and vehicle-to-everything (V2X) in recent years, as well as the reduction in battery costs and improvement in performance, electric vehicles are becoming increasingly economical and will become an important component of future urban construction, including intelligent transportation and smart cities. Currently, the vast majority of electric vehicles are charged via wired charging stations. Therefore, wireless charging has become an important future development direction for electric vehicles. Currently, the highest power of wireless charging reaches 22KW, greatly reducing charging time and making electric vehicle travel more free and convenient. However, for large electrical equipment, current wireless charging still faces limitations and challenges such as transmission efficiency, cost, and charging distance, and a few core technologies have not yet been fully mastered, thus preventing its widespread market adoption. Current wireless charging systems generally use electromagnetic induction. That is, there is a power transmitting coil on the ground and a receiving coil on the vehicle, and the transmitting and receiving coils transmit energy through magnetic field coupling. Therefore, power transmission efficiency and system safety are the two most critical factors. However, foreign objects can fall into or enter the magnetic field coupling region between the primary and secondary sides at any time. If the foreign object is metallic, the alternating magnetic field will induce eddy currents within it, causing the temperature of the metallic object to rise sharply, burning out the equipment, or even causing a fire. Therefore, effectively detecting potential foreign objects and promptly stopping power transmission is a necessary process and key technology to ensure the normal, safe, and reliable operation of the wireless power supply system.

[0043] Currently, there are many foreign object detection (FOD) technologies in the industry, mainly divided into direct detection methods and indirect detection methods. Direct detection methods generally rely on various devices and technologies such as visual cameras, image recognition, millimeter-wave radar, and infrared thermal imaging sensors to detect foreign objects. Indirect detection methods detect foreign objects by measuring changes in various signals, such as magnetic fields, transmission efficiency (loss), detection coil impedance, or the surface temperature of the transmitting end area. Additionally, there are methods that use mechanical or structural devices to avoid foreign objects; for example, adding a ground-based foreign object removal device, or raising the ground end during charging to make close contact with the vehicle end without any gap, to prevent foreign object intrusion. However, direct detection methods and mechanical / structural device avoidance methods significantly increase the overall cost of wireless charging systems. Furthermore, harsh outdoor environments and increased susceptibility to vandalism or theft greatly reduce system reliability and result in very high daily maintenance costs. Therefore, direct detection methods and mechanical / structural device avoidance methods have poor real-time performance.

[0044] Therefore, most industry methods currently employ indirect signal detection. However, deploying and detecting the temperature of all surface areas outdoors is extremely difficult, and the losses caused by tiny metal foreign objects during high-power charging (several kilowatts) are also extremely weak. Therefore, detecting only magnetic field and coil impedance signals is practically feasible, and the industry often achieves this by detecting a resonant circuit formed by the coil: the intrusion of a metal foreign object causes changes in parameters such as inductance and resistance in the resonant circuit, thus leading to changes in the measured value. Currently, all manufacturers in the industry can only detect metal foreign objects during charging at power levels below 11 kilowatts, but cannot solve the application challenges of higher-power fast charging: higher charging power (22 kilowatts) will generate stronger magnetic field interference, and in harsh environments such as rain and snow cover, and drastic temperature changes, tiny metal foreign objects (such as a penny or a 29mm paperclip) will be undetectable, or result in a high false detection rate.

[0045] In summary, how to improve the accuracy of foreign object detection while keeping costs down is a pressing technical problem. This application provides a foreign object detection method, system, storage medium, and program product that can improve the accuracy of foreign object detection while keeping costs down.

[0046] Reference Figures 1 to 3 As shown, a wireless charging system according to an embodiment of this application includes:

[0047] The detection coil matrix 100 is composed of multiple pairs of paired detection coils 110 arranged in an array. The first end of each detection coil 110 is connected to a capacitor, and the second end of the detection coil 110 is grounded to form a resonant circuit. A sampling point is set at the first end of the capacitor away from the detection coil 110.

[0048] The acquisition circuit module 200 is used to send excitation signals to each resonant circuit and activate two resonant circuits corresponding to the same detection coil pairing group at the same time; to detect the voltage state of each activated resonant circuit and obtain the voltage state data of each resonant circuit at the sampling point; wherein, the voltage state data characterizes the voltage change relationship between the corresponding sampling point and time.

[0049] The processing module 300 is used to determine the deviation state data of each pair of detection coils based on the state deviation between two voltage state data of the same pair of detection coils at the same time; and to obtain foreign object detection data based on the voltage state data and the deviation state data.

[0050] Reference Figure 2 As shown, the distribution area of ​​the detection coil matrix 100 in this embodiment needs to cover the range of wireless power transmission and reception; as Figure 2As shown, the detection coil matrix 100 covers the wireless power transmission and reception range of the receiving coil 420 and the transmitting coil 410. The detection coil matrix 100 can accurately identify metallic foreign objects within the wireless power transmission and reception range, thereby reducing the risk of fires caused by eddy current heating; for metallic foreign objects outside the range, the distribution of the detection coil matrix 100 should not cause safety hazards or performance degradation (such as causing a serious reduction in charging efficiency) to the wireless charging system.

[0051] It is understood that the detection coils in the detection coil matrix adopt a symmetrical design and layout. For example, in some embodiments, the detection coil matrix is ​​composed of two completely symmetrically designed and laid-out sub-coil plates on the left and right; a single sub-coil plate is composed of M*N detection coils of the same small size arranged in a matrix. The detection coils in the embodiments of this application can be selectively set according to actual needs.

[0052] Understandably, two paired detection coils form a detection coil pairing group. The two detection coils in the pairing group should have basically the same coil parameters and power sensing characteristics, and the spacing between them should meet the preset distance. Each pairing group of detection coils is paired and tested and calibrated before leaving the factory, and the deviation values ​​between each paired coil are saved as fixed deviations for configuration (such as fixed voltage deviation values ​​and fixed phase deviation values).

[0053] Understandably, voltage state data includes at least one voltage parameter, such as voltage phase and voltage amplitude. When voltage state data contains multiple voltage parameters, the state deviation is the state deviation between various voltage parameters of two detection coils in the same detection coil pairing group. For example, if the detection coil pairing group includes coil 1 and coil 2, the difference between the voltage phase of coil 1 and the voltage phase of coil 2 represents the voltage phase deviation value, which is one of the deviation state data of the detection coil pairing group. For the same detection coil pairing group, when power charging is not enabled, the values ​​of each basic measurement point of the two detection coils remain at the fixed deviation before leaving the factory. After power charging is enabled, the values ​​of each measurement point of the two detection coils change simultaneously and synchronously with the power change. If there are no metal foreign objects on the two detection coils, the values ​​of each measurement point on the two detection coils still remain at the fixed deviation value. Assuming that there is a foreign object in one of the detection coils, then the values ​​of each measurement point between the paired coils will no longer maintain the inherent deviation value. At this time, the change in difference may be introduced by the foreign object. Thus, the differential noise reduction algorithm for the detection coil pairing group is realized in the above way.

[0054] It should be noted that when running the differential noise reduction algorithm, the resonant circuits corresponding to the two detection coils in the same detection coil pairing group need to be simultaneously selected and acquired. Assume that the left 0# small coil is paired with the right 31# small coil, the left 1# small coil is paired with the right 30# small coil, and so on; therefore, when the left input selects channel 0#, the right simultaneously selects channel 31#; when the left inputs channel 1#, the right simultaneously selects channel 30#. This achieves simultaneous acquisition of the voltage state data on the paired detection coils on both sides. Then, the voltage state data of the two detection coils in the same pairing group are differentially calculated according to each voltage parameter, thereby implementing the differential noise reduction algorithm and determining the deviation state data of each detection coil pairing group.

[0055] Understandably, referring to Figure 3 As shown, the physical parameters of each detection coil 110 (e.g.) Figure 3 The outer diameter (dout), inner diameter (din), line width (w), line spacing (s), and process parameters (such as copper foil, plate thickness, etc.) should be kept as consistent as possible. The performance of each detection coil 110 should be improved as much as possible (e.g., setting a smaller resistance value, a higher self-resonant frequency, and a higher Q value), thereby improving the detection sensitivity of the detection coil 110.

[0056] The processing module can be configured as an integrated chip or microcontroller unit module or terminal device with logic operation functions. Those skilled in the art are not limited in this regard. In some embodiments, the processing module initializes key components or chips, including FPGAs, ADCs, and DDSs. For example, it sets the clock division ratio, sampling rate, and output data format of the ADC chip, and the operating mode, clock multiplication, and output frequency of the DDS chip. After initialization, the DDS module outputs two orthogonal AC signals UI / UQ at a frequency equal to the pre-set base frequency fs.

[0057] Understandably, such as Figure 3 As shown, the detection coil 110 can be equivalent to a series connection of coil inductance L and coil resistance R. The outer end (i.e., the second end) of the detection coil 110 is grounded, and a capacitor C is connected in series with the inner end (i.e., the first end) of the detection coil 110, thus forming a resonant circuit. When the excitation signal flows through the detection coil 110, a high-frequency magnetic field is induced. If a metallic foreign object enters the detection coil 110, the eddy current effect and magnetic effect cause changes in its coil inductance L and coil resistance R. Due to the change in the resonant circuit parameters, the voltage state information at any measurement point in the circuit will change accordingly. By observing the change in the voltage state at the sampling point, the foreign object can be detected.

[0058] Since the deviation state data of each pair of detection coils is fixed when no foreign object enters, it changes when a foreign object enters. The presence of a foreign object in each detection coil can be determined by comprehensively considering the change in deviation state data, voltage state change trend, and change amount. Different types of foreign objects cause different changes and trends, thus identifying the type of foreign object. Furthermore, since there are multiple detection coils within the detection range, the movement of the foreign object can be identified by observing the changing positions of the detection coils and whether the detection coil containing the foreign object changes. Therefore, this application does not limit the foreign object detection data obtained from voltage state data and deviation state data; those skilled in the art can selectively configure these settings according to actual needs.

[0059] Understandably, voltage state data includes voltage amplitude and voltage phase, and the acquisition circuit module includes:

[0060] A filter amplifier circuit is used to amplify and filter the voltage signal at the sampling point.

[0061] An amplitude detection circuit is connected to the output of a filter amplifier circuit. The amplitude detection circuit is used to detect the amplitude of the voltage signal output by the filter amplifier circuit to obtain the voltage amplitude at each sampling point.

[0062] The phase detection circuit is connected to the output of the filter amplifier circuit. The phase detection circuit is used to detect the phase difference of the voltage signal output by the filter amplifier circuit to obtain the voltage phase at each sampling point.

[0063] In some embodiments, refer to Figure 4 As shown, the filter amplifier circuit includes an amplitude conditioning amplifier unit and a bandpass filter. The voltage signal is amplified by the amplitude conditioning amplifier unit and filtered by the bandpass filter, thereby achieving voltage signal conditioning.

[0064] In some embodiments, a high-performance ADC chip can be used to achieve high-speed sampling. Simultaneously, to suppress common-mode noise and interference, an ADC driver can be added to condition the differential input signal of the ADC chip. Differential input signal conditioning includes amplitude adjustment, single-ended to differential conversion, buffering, common-mode bias adjustment, and filtering. The ADC driver is typically a differential operational amplifier, whose input is the voltage signal to be detected, and whose output differential pair signal is connected to the analog input terminal of the ADC chip. The ADC chip performs analog-to-digital conversion on the differential pair signal. In some embodiments, the result of the ADC chip's analog-to-digital conversion is output to an FPGA for filtering; at this time, the voltage amplitude is the data after FPGA filtering.

[0065] In some embodiments, the phase detection circuit includes an attenuation network and two phase detectors. The voltage signal enters the two phase detectors via the attenuation network for phase difference detection. The reference signals for each phase detector are two orthogonal UI / UQ signals. Due to deviations in the filter circuit parameters of UI / UQ, the phase difference between them may no longer be 90 degrees. Therefore, the phase difference between UI / UQ is also detected by the two phase detectors, which can be used for compensation in software algorithms.

[0066] For example, such as Figure 4 As shown, the two phase detectors are phase detector 1 and phase detector 2. The voltage signal Us is successively amplified by amplitude conditioning and then filtered by a bandpass filter to achieve voltage signal conditioning. It is then output to two branches via a power divider or follower. One output of the power divider or follower is fed into a high-speed ADC chip via an ADC driver for amplitude sampling; the other output is fed into phase detectors 1 and 2 via an attenuation network for phase sampling. Phase detectors 1 and 2 are based on two orthogonal signals, UI and UQ, respectively, where UI is the excitation signal source for each detection coil. In some embodiments, the amplitude sampling result of the ADC is input to an FPGA to implement digital filtering of the ADC and its sampling results. For example, the FPGA can flexibly configure the high-performance ADC chip (such as reset, clock division ratio, sampling rate, output data format, internal testing, etc.) through serial or parallel ports to meet functional and operational needs. FPGA can also provide a sampling clock signal to the ADC chip and read the sampling results from the ADC chip. Furthermore, due to strong electromagnetic interference during high-power charging, the analog signal sampled by the ADC contains noise from other frequencies besides the fundamental frequency (fs), which severely affects the identification of small foreign objects. By using the FPGA to execute an FFT filtering algorithm to remove the noise spectrum data other than the fundamental frequency (fs), the filtered data is then sent to the processing module, thereby ensuring the accuracy of the voltage amplitude.

[0067] Understandably, the data acquisition circuit module also includes:

[0068] The system includes at least two input multiplexers. The input terminal of each input multiplexer is used to input the excitation signal, and each output terminal of each input multiplexer is connected to the input terminal of a resonant circuit. Furthermore, the two resonant circuits corresponding to the same pair of detection coils are connected to different input multiplexers.

[0069] The system includes multiple output multiplexers, with each input terminal of each output multiplexer connected to the output terminal of a resonant circuit. Furthermore, the two resonant circuits corresponding to the same pair of detection coils are connected to different output multiplexers. The output terminal of each output multiplexer is connected to the input terminal of a filter amplifier circuit.

[0070] Understandably, considering cost and size, input and output multiplexers can be used to acquire sampling points from multiple detection coils in a time-division manner. Multiple resonant circuits share both the input and output multiplexers, respectively. By controlling the input multiplexer, the excitation signal UI is sequentially input into each resonant circuit; simultaneously, the output multiplexer is synchronously controlled to sequentially output the voltage signal Us from each sampling point in the resonant circuit. Furthermore, to implement the differential noise reduction algorithm, the two resonant circuits corresponding to the same detection coil pairing group need to be selected and acquired simultaneously.

[0071] This application does not limit the number or model of input and output multiplexers; those skilled in the art can choose adaptive settings according to actual needs. For example, the detection coil pairing group can be divided into M groups, with each M group sharing two input multiplexers to ensure simultaneous selection and acquisition of the two resonant circuits corresponding to the same detection coil pairing group. Correspondingly, the output multiplexer is configured based on its supported output channels.

[0072] like Figure 5 As shown, two input multiplexers are set up to connect to one detection coil in each of the pairing groups of detection coils. By controlling the two input multiplexers to simultaneously select the detection coil in the same pairing group and to turn on the channel connected to it in the output multiplexer, the voltage signals of the two detection coils in the same pairing group can be acquired simultaneously.

[0073] Understandably, the acquisition circuit module also includes an excitation signal source circuit, which is used to provide excitation signals to each resonant circuit and to provide phase reference signals to the phase detection circuit.

[0074] Understandably, the fundamental frequency of the excitation signal can be obtained by sweeping the frequency of the detection coil matrix. The resonant frequency of the detection coil matrix can be determined as follows:

[0075] First, obtain the coil inductance, coil resistance, and quality factor values ​​from all detection coils. Select detection coils that meet the quality threshold from these quality factor values. Then, initially choose a resonant frequency for the selected detection coils; a higher resonant frequency is better. At this point, since the values ​​of fr and L are known, the formula can be used... The C value of the capacitor to be connected in series in each resonant circuit is calculated. Although each detection coil is designed consistently, the L value may still have slight differences; by precisely matching the C value of the capacitor, the resonant frequencies can be ensured to be as consistent as possible. Finally, the center value (or average value) of each actual resonant frequency is taken as the unified circuit resonant frequency fr point, which is also the resonant frequency of the detection coil matrix. At this point, based on this resonant frequency, the frequency point where the voltage amplitude change at the measurement point before and after metal intrusion is determined, that is, the point with the maximum slope of the characteristic curve of the measurement point.

[0076] Understandably, the excitation signal source circuit includes:

[0077] Digital synthesizer; the digital synthesizer outputs two quadrature AC signals.

[0078] The excitation signal processing circuit has two circuits, which perform stability processing on the two orthogonal AC signals respectively.

[0079] One of the excitation signal processing circuits provides an excitation signal to each resonant circuit and a phase reference signal to the phase detection circuit; the other excitation signal processing circuit provides a phase reference signal to the phase detection circuit.

[0080] Understandably, the digital synthesizer (DDS) outputs two orthogonal high-frequency AC signals as the excitation source. The excitation signal processing circuit can perform stability processing on the corresponding orthogonal AC signals, including differential-to-single-ended conversion, low-pass filtering, amplitude conditioning amplification, and band-pass filtering. For example... Figure 6 As shown, the DDS acts as the excitation source, outputting two orthogonal high-frequency AC signals. Each signal passes through its respective excitation signal processing circuit, which converts the signal to a single-ended output, performs a low-pass filter, amplitude conditioning amplification, and a band-pass filter, generating orthogonal UI / UQ signals. The UI / UQ signals are then output through a power divider or follower to multiple branches. The UI signal is fed to phase detector 1 and the resonant circuit via the power divider or follower; the UQ signal is fed to phase detector 2. Using the two orthogonal UI / UQ signals as reference signals for the phase detectors, phase difference detection can be performed on the voltage signals at the sampling points.

[0081] In summary, the wireless charging system of this application achieves low-cost detection of tiny metallic foreign objects through measures such as symmetrical design of detection coils, pairing of two coils, synchronous acquisition, and differential noise reduction. It is particularly effective in accurately detecting these objects under harsh environments such as high-power charging, strong magnetic field interference, rain and snow cover, and drastic temperature changes, thereby significantly improving the stability and safety of the wireless power transmission system.

[0082] The wireless charging system of this application adopts a symmetrical design. The detection coil matrix is ​​spliced ​​together from two symmetrically designed and laid-out sub-coil boards on the left and right. Each sub-coil board is composed of an array of detection coils with consistent parameters. All detection coils on the left and right sub-coil boards are paired up. Pre-shipment testing and calibration are performed, and the deviation values ​​between each paired coil under different power are saved. High-speed and synchronous acquisition of measurement point information of paired coils is achieved through a high-performance dual-channel ADC. Through differential algorithm, common-mode noise and interference on the two paired detection coils during high-power charging can be reduced. Thus, foreign object scene recognition and foreign object analysis can be achieved based on voltage state data and differential state data. For example, the voltage state of all detection coils can be traversed to find synchronous or regular changes caused by the scene. The position of each affected detection coil can be analyzed, and the shape or outline of the large metal foreign object can be roughly outlined and the movement of the foreign object can be judged.

[0083] The wireless charging system in this application embodiment can be any type of automotive wireless charging system, including various pure electric, range-extended electric, hybrid, fuel cell electric, and hydrogen engine vehicles. Types include trucks, off-road vehicles, dump trucks, tractor units, special-purpose vehicles, buses, sedans, semi-trailers, etc. By accurately identifying tiny metallic foreign objects in all wireless charging scenarios, it avoids safety hazards such as fires, ensures the safe and stable operation of the charging system, and improves the availability of the charging system.

[0084] Understandably, the capacitance is determined through the following steps:

[0085] Obtain the coil inductance and coil resistance values ​​of each detection coil;

[0086] Based on the measured values ​​of coil inductance and coil resistance of each detection coil, the estimated value of the quality factor of each detection coil is determined.

[0087] Based on the estimated quality factor of each detection coil, the reference resonant frequency of the detection coil matrix is ​​determined.

[0088] Input the measured inductance values ​​of each coil, the corresponding estimated quality factor, and the reference resonant frequency into the preset resonant frequency calculation formula to obtain the predicted capacitance values ​​of the capacitors on each resonant circuit.

[0089] The capacitor model is determined based on the predicted capacitance value of each capacitor.

[0090] The measured values ​​of coil inductance and coil resistance are obtained from actual measurements of the detection coil, respectively. Resonant frequency calculation formula. Where fr is the resonant frequency of the resonant circuit, L is the coil inductance of the resonant circuit, and C is the capacitance of the resonant circuit.

[0091] For example, assuming the coil inductance is measured as L and the coil resistance as R, the estimated quality factor can be obtained according to the quality factor calculation formula. Where ω is the angular frequency. The reference resonant frequency is determined based on the quality factor prediction. Then, for coil 1, the predicted capacitance value of the capacitor in coil 1 can be determined based on the L of coil 1 and the reference resonant frequency.

[0092] According to an embodiment of this application, a foreign object detection method for a wireless charging system is provided, referring to... Figure 2 and Figure 3 As shown, the wireless charging system includes a detection coil matrix, which consists of multiple pairs of paired detection coil arrays. Each detection coil has a capacitor connected to its first end, and its second end grounded to form a resonant circuit. A sampling point is positioned at the first end of the capacitor furthest from the detection coil. (Refer to...) Figure 7 As shown, the method includes:

[0093] Step S100: Send excitation signals to each resonant circuit and activate the two resonant circuits corresponding to the same detection coil pairing group simultaneously;

[0094] Step S200: Obtain the voltage state data of each activated resonant circuit at the sampling point, wherein the voltage state data characterizes the voltage change relationship between the corresponding sampling point and time.

[0095] Step S300: Based on the state deviation between the two voltage state data of the same detection coil pairing group at the same time, determine the deviation state data of each detection coil pairing group respectively.

[0096] Step S400: Obtain foreign object detection data based on voltage status data and deviation status data.

[0097] Therefore, by pairing detection coils in pairs to form a detection coil pairing group and deploying it within the working range of the transmitting and receiving coils, and acquiring the deviation state data of the same detection coil pairing group at the same time, the state deviation between the two detection coils within the same detection coil pairing group can be determined. Simultaneously, by combining the voltage state data of each detection coil, it is possible to achieve foreign object detection from multiple different dimensions without increasing additional hardware deployment and maintenance costs. Therefore, compared with related technologies, the embodiments of this application can improve the accuracy of foreign object detection while considering cost.

[0098] The "simultaneous" in step S100 can be understood as triggering the activation of the two resonant circuits corresponding to the same detection coil pairing group within a very small time difference, so as to ensure that the acquisition of the two detection coils in the same detection coil pairing group is synchronized.

[0099] The voltage state data in step S200 may include at least one voltage parameter, including at least one of voltage phase and voltage amplitude.

[0100] Step S300 can implement a differential noise reduction algorithm. When charging at high power or changing power, the sensed interference signal is very large, which seriously affects the identification of small metal foreign objects such as coins and paperclips. By calculating the state deviation of two voltage state data of the same detection coil pair group at the same time, the common mode interference of power noise can be reduced or filtered out, thereby improving the accuracy of identifying small metal foreign objects.

[0101] The foreign object detection data in step S400 may include foreign object type, foreign object outline, foreign object motion recognition, etc. This application embodiment does not limit this, and those skilled in the art can selectively set it according to the actual situation.

[0102] Understandably, voltage state data includes voltage amplitude and voltage phase; based on the state deviation between two voltage state data points of the same pair of detection coils at the same time, the deviation state data for each pair of detection coils is determined, including:

[0103] The voltage deviation value is obtained by calculating the difference between the two voltage amplitudes of the same pair of detection coils at the same time.

[0104] The phase deviation value is obtained by calculating the difference between the two voltage phases of the same pair of detection coils at the same time.

[0105] Based on the voltage deviation value and the corresponding phase deviation value, the deviation status data of the corresponding detection coil pairing group is obtained.

[0106] For example, assuming that at time t, the voltage amplitude and voltage phase of the two detection coils (coil 1 and coil 2) in detection coil pairing group 1 are amplitude 1, amplitude 2, phase 1, and phase 2, respectively; then, subtracting the amplitude 1 of coil 1 at time t from the amplitude 2 of coil 2 at time t yields the voltage deviation value; subtracting the phase 1 of coil 1 at time t from the phase 2 of coil 2 at time t yields the phase deviation value. Combining the voltage deviation value and the phase deviation value yields the deviation status data of detection coil pairing group 1. The deviation status data of other detection coil pairing groups can also be obtained by referring to detection coil pairing group 1.

[0107] Therefore, by calculating the difference of the same voltage parameter type in the voltage state data and combining the differences of multiple voltage parameter types to obtain the deviation state data, the accuracy of the state deviation between two detection coils in the same detection coil pairing group can be further ensured.

[0108] Understandably, foreign object detection data is obtained based on voltage state data and deviation state data, including:

[0109] Based on the deviation status data, determine whether there are foreign objects within the detection range of the detection coil matrix;

[0110] If the presence of a foreign object is confirmed, the foreign object scenario type is obtained; the foreign object scenario type is determined based on the voltage state data.

[0111] When the foreign object scenario type indicates that foreign object detection needs to be activated, foreign object detection data is obtained based on voltage status data.

[0112] Foreign object scenarios can include changes in ambient temperature, rain and snow cover, vehicle alignment in progress, and rapid passage of metallic foreign objects. Identifying the type of foreign object scenario beforehand can reduce the impact of scenario factors on foreign object identification.

[0113] Understandably, when no foreign object enters, the state deviation between the two detection coils in the same detection coil pairing group is fixed. When a foreign object enters, the state deviation between the two detection coils in the same detection coil pairing group varies or remains fixed but differs from the value when no foreign object enters. Therefore, by analyzing the deviation state data of the detection coil pairing groups across the entire detection coil matrix, it is possible to determine which detection coil pairing groups may have been affected by foreign objects.

[0114] Understandably, the deviation status data includes voltage deviation and phase deviation values; based on the deviation status data, it is determined whether there are foreign objects within the detection range of the detection coil matrix, including:

[0115] Obtain the fixed voltage deviation value and fixed phase deviation value configured for each pair of detection coils;

[0116] The voltage deviation value is compared with the corresponding fixed voltage deviation value by voltage difference, and the phase deviation value is compared with the corresponding fixed phase deviation value by phase difference;

[0117] Based on the comparison results of voltage difference and phase difference, it was determined that there was a foreign object in the detection coil of the detection coil pairing group.

[0118] In some embodiments, taking a pair of detection coils as an example, if the voltage difference comparison result indicates that the difference between the voltage deviation value and the fixed voltage deviation value is outside a preset threshold, and the phase difference comparison result indicates that the phase deviation value and the fixed phase deviation value are outside a preset threshold range, then a foreign object is determined to be present. In other embodiments, if the voltage difference comparison result indicates that the difference between the voltage deviation value and the fixed voltage deviation value is outside a preset threshold, or if the phase difference comparison result indicates that the phase deviation value and the fixed phase deviation value are outside a preset threshold range, then a foreign object is determined to be present. Those skilled in the art can selectively configure these settings according to actual circumstances.

[0119] Understandably, the steps to determine the type of foreign object scene are as follows:

[0120] Acquire reference voltage state change data under multiple preset foreign object scenarios;

[0121] Based on the voltage state data, the actual voltage state change data of the detection coil matrix is ​​obtained;

[0122] By matching the actual voltage state change data with the reference voltage state change data, the foreign object scenario type can be obtained.

[0123] Understandably, car charging is mostly used outdoors, in various scenarios with complex operating conditions. Identifying the scenario type reduces the probability of false or missed detections of foreign objects. The system can iterate through the voltage state data of all detection coils to find synchronous or regular changes caused by the scenario type, and determine the foreign object scenario type based on these synchronous or regular changes.

[0124] It is understood that the reference voltage state change data can be determined through laboratory measurements or simulations. Therefore, this application does not impose any restrictions on how the reference voltage state change data is determined. The reference voltage state change data is configured to correspond one-to-one with the foreign object scenario type.

[0125] Actual voltage state change data characterizes the trend and magnitude of voltage parameter changes. When the actual voltage state change data matches the reference voltage state change data, the type of foreign object scenario can be determined based on the reference voltage state change data.

[0126] Understandably, based on voltage state data, foreign object detection data is obtained, including:

[0127] Based on the preset foreign object characteristic threshold conditions and voltage state data, the target detection coil containing foreign objects is determined;

[0128] Determine the outline of the foreign object based on the position information of the target detection coil;

[0129] Based on the voltage state data of the target detection coil, the voltage change trend of the target detection coil is determined, and the type of foreign object is determined based on the voltage change trend.

[0130] Understandably, charging conditions vary, and the material, size, and location of intruding foreign objects also differ; therefore, the impact of foreign objects on the resonant circuit varies. In some cases, the voltage amplitude change at the measuring point is more significant; in others, the phase change at the measuring point is more sensitive, and so on. By combining voltage state data with foreign object characteristic threshold conditions, accurate detection of foreign objects can be achieved.

[0131] Understandably, if the foreign object is large, it will simultaneously and significantly affect multiple detection coils; by analyzing the changes in the position and voltage status data of each affected detection coil, the shape or outline of the foreign object can be roughly delineated.

[0132] Foreign object type is used to identify the movement of foreign objects and determine whether charging needs to be stopped. Voltage change trends include various scenarios such as increasing, decreasing, or shifting. For example, if the voltage change trend is from small to large, or the number of coils showing numerical changes shows an increasing trend or a shifting trend in a certain direction, it is considered that a foreign object has entered. After a period of time, if the measured value changes from large to small, or the number of coils showing numerical changes returns to zero, it is considered that the foreign object has exited or left. If the foreign object passes by quickly, charging generally does not need to be stopped.

[0133] Understandably, voltage state data includes voltage amplitude and voltage phase, and foreign object characteristic threshold conditions include at least one of the following:

[0134] If the voltage amplitude of the resonant circuit where the detection coil is located is greater than the first amplitude threshold, the detection coil is determined to be the target detection coil.

[0135] If the voltage phase of the resonant circuit where the detection coil is located is greater than the first phase threshold, the detection coil is determined to be the target detection coil.

[0136] If the voltage amplitude of the detection coil and the adjacent detection coil are both greater than the second amplitude threshold or the voltage phase is greater than the second phase threshold, the detection coil is determined to be the target detection coil.

[0137] In some embodiments, one of the above conditions can be selected to determine the target detection coil based on the scenario type. In other embodiments, multiple conditions can be used to determine the same detection coil, and the detection coil is determined to be a target detection coil only when multiple conditions are met. Those skilled in the art can selectively configure these conditions according to actual needs.

[0138] Adjacent detection coils can be understood as detection coils that are placed next to each other in the decision.

[0139] In summary, the embodiments of this application have the following beneficial effects:

[0140] 1. Precise detection: By designing the detection coils in a consistent manner and using high-speed, high-precision, and synchronous acquisition technology for the sampling points of each detection coil, the accuracy of foreign object detection can be greatly improved.

[0141] 2. Flexible and versatile: By first identifying the scene type and then detecting foreign objects, it can support more scenes and working conditions, and can be applied to wireless charging systems of various types of vehicles such as trucks, off-road vehicles, buses, cars, and semi-trailers, making it more versatile;

[0142] 3. Cost leadership: Based on ground-based detection coils and input / output multiplexer technology, foreign object detection is accurate and stable, greatly reducing the hardware and maintenance costs of the system;

[0143] 4. Enhanced Safety: Coil pairing and differential noise reduction algorithms enable accurate identification of tiny metal foreign objects such as paperclips in harsh environments such as high power, high noise, rain and snow, and drastic temperature changes, thus better reducing safety hazards such as fires and ensuring the safe operation of the charging system.

[0144] For example, refer to Figures 2 to 6 This application describes a wireless charging system and a foreign object detection method for the wireless charging system, based on embodiments of the present application. Taking a wireless charging system supporting passenger cars and SUVs as an example, the wireless charging system includes an on-board wireless charger and a wireless charging ground device. The wireless charging ground device is located on the ground side and includes a transmitting coil and a controller for the wireless charging ground; the on-board wireless charger is located on the vehicle side and includes an on-board receiving coil and a controller.

[0145] The wireless charging ground controller can convert industrial frequency AC to high frequency AC, with an AC input voltage of 320V–460V and a frequency of 45Hz–66Hz; the DC output charges the battery with a rated voltage of 800V, ranging from 650V to 915V. The transmitting coil of the wireless charging ground unit achieves energy transmission through a resonant circuit design and features foreign object detection (FOD), liveness detection (LOD), and position detection (PD). The vehicle-mounted wireless charger achieves energy reception and position sensing through a receiving coil and position sensing circuit design, converting high-frequency AC to DC to power high-voltage assemblies such as vehicle batteries, 12VDC / DC converters, and water heaters. In this embodiment of the application, when the wireless charging system outputs a maximum charging power of 22KW, it can still 100% identify tiny metallic foreign objects above the transmitting coil that may affect wireless power transmission, such as a one-cent coin, an M5 screw, or a 29mm long paperclip. Upon detecting a foreign object, the system issues a warning and stops charging, with no false alarms. Specifically:

[0146] I. Design of the ground-side detection coil matrix:

[0147] 1. Coverage Area: The detection coil matrix needs to completely cover the wireless power transmission and reception range. (Refer to...) Figure 2 As shown, the ground-based transmitting coil 410 is larger than the vehicle-mounted receiving coil 420. The transmitting coil 410, including the frame, is approximately 650mm x 500mm in length and width. Therefore, the detection coil matrix 100 is designed to be larger, approximately 720mm x 560mm.

[0148] 2. Symmetrical design: The entire detection coil matrix is ​​composed of two completely symmetrically designed and laid-out sub-coil plates on the left and right; the dimensions of the left and right sub-coil plates are both 360mm*560mm, and each has 4*8 detection coils, with the detection coil dimensions being 84mm*64mm;

[0149] 3. Consistent Parameters: The physical parameters (such as outer diameter, inner diameter, line width, and line spacing) and process parameters (such as copper foil and plate thickness) of the 64 detection coils are designed to maintain consistency, thereby improving the performance of the detection coils. For example, the self-resonant frequency of the detection coil is approximately 9MHz, the self-inductance is approximately 5uH, and the resistance is approximately 3 ohms.

[0150] II. Design the hardware for the foreign object detection unit and collect voltage state data from the sampling points of all detection coils:

[0151] 1. Resonant circuit:

[0152] Reference Figure 3As shown, the outer end (i.e., the second end) of each detection coil is grounded, and a 560pF capacitor C is connected in series with the inner end (i.e., the first end) of each detection coil, thus forming a series resonant circuit. The self-inductance L of each detection coil is measured to obtain the coil inductance detection value. The 560pF capacitor is finely adjusted (e.g., by connecting a small capacitor in series or parallel) so that the resonant frequency fr of all resonant circuits is the same, which is 3.0MHz.

[0153] 2. Motivation source:

[0154] like Figure 6 As shown, the DDS chip is set to AD9854. The AD9854 integrates two high-speed, high-performance quadrature D / A converters, which can output highly stable I and Q differential sine and cosine signals with programmable frequency, phase, and amplitude; the frequency resolution reaches 1µHz at a 300MHz system clock.

[0155] The fundamental frequency fs of the DDS chip can be determined by the frequency sweep method. For example, starting from 3.0MHz (which is also the resonant frequency of the resonant circuit), with a step size of 1KHz, the frequency of the AD9854 output signal is gradually increased, and the change in the voltage amplitude at the measuring point in the resonant circuit after metal intrusion is measured. The frequency point with the most significant change is found, which is about 3.20MHz. That is, 3.20MHz is the fundamental frequency fs of the I / Q signals.

[0156] Reference Figure 6 As shown, the I and Q fundamental frequency signals are processed by differential to single-ended conversion, low-pass filtering, amplitude conditioning amplification, band-pass filtering, and power divider (follower) to obtain UI / UQ. The UI signal serves as the common input of all detection coils and also as the reference signal for phase detection.

[0157] 3. Time-sharing data collection:

[0158] like Figure 5 As shown, voltage signals from sampling points in 32 resonant circuits on both the left and right sub-coil boards are acquired in a time-division manner using an input multiplexer. Both the input and output multiplexers use 32-channel ADG732 chips; therefore, a total of four ADG732 chips are used.

[0159] The time-division acquisition of the left and right coil boards is exactly the same.

[0160] Taking the left half-coil board as an example, the excitation signal UI is injected into 32 resonant circuits in turn via the input ADG732. The voltage signals at the sampling points in the 32 resonant circuits are selected and output by the output ADG732, and then processed by a follower and a differential operational amplifier to complete signal separation, obtaining the voltage signal Us of the measurement point to be acquired. By synchronously selecting different channels with two ADG732s, the signal acquisition of the measurement points in the 32 resonant circuits in turn is realized.

[0161] 4. Conditioning, sampling, and processing:

[0162] Reference Figure 4 As shown, the voltage signal Us of the sampling point output by ADG732 is amplified by amplitude conditioning and filtered by a bandpass filter, and then passed through an operational amplifier follower to output multiple branches. These branches are respectively used for high-speed, high-precision, and synchronous amplitude detection by an amplitude detection circuit, and for high-speed, high-precision, and synchronous phase detection by a phase detection circuit.

[0163] Reference Figure 4 As shown, for the amplitude detection circuit: the voltage signal at the sampling point is conditioned by the differential operational amplifier ADA4932 (i.e., the ADC driver shown in the diagram) to generate a detection signal with a common-mode voltage of 0.9VDC and a maximum amplitude of 1.8VAC, which is then sent to the AD9635 for analog-to-digital conversion. The AD9635 is a dual-channel, 12-bit, 80 / 125MSPS ADC chip. The dual-channel input of the AD9635 is the detection signal Us of the paired small coils on the left and right sides; this achieves high-speed, high-precision, and synchronous amplitude detection.

[0164] Understandably, such as Figure 4 As shown, the output of the ADC chip also needs to be sent to the processing module via the FPGA. Figure 4 As shown, the FPGA first configures the operating mode of each AD9635 chip via the SPI serial port, such as single frame, DDR dual channel, 12-bit sampling output, etc.; then, after reading the conversion result data through the LVDS interface, it performs filtering processing on the data: 1024 data points are read each time, and different spectrum values ​​are obtained through the FFT algorithm, removing data outside 3.20MHz. The processed data is then sent to the processing module.

[0165] Understandably, such as Figure 4 The phase detection shown requires a voltage signal to be input through the sampling point, which is then fed into the phase detector AD8302 via an attenuation network for phase difference detection (as well as phase detector 2). Since the AD8302 has excellent linearity in its central region but poor linearity at its edges (around 0 or 180 degrees of phase difference), two phase difference measurements were performed using UI and UQ generated by the DDS as reference signals, and the measurement results were sent to the processing module.

[0166] The phase difference measurement results are processed as follows: Normally, the phase difference value is measured using UI as the reference signal. If this value is at an edge (e.g., 0–30 degrees or 150–180 degrees), then the phase difference value is measured using UQ as the reference signal. Because the reference signal phase changes by approximately 90 degrees, the measurement point shifts to the central region (60–120 degrees) where linearity is best, significantly improving test accuracy. Furthermore, the phase difference between UI and UQ may no longer be 90 degrees due to differences in circuit parameters; therefore, it is also necessary to detect the phase difference between UI / UQ for algorithm compensation. This further achieves high accuracy in phase detection.

[0167] Simultaneously, the system used five AD8302 diodes to perform phase detection of the voltage signals and UI / UQ of the paired small coils on both sides. This further enabled high-speed and synchronous phase detection.

[0168] Third, the processing module executes the foreign object detection algorithm based on the sampling point values ​​of all detection coils. Specific steps are detailed in the documentation. Figure 8 as follows:

[0169] Step 1: Noise Reduction: Run a differential algorithm to reduce common-mode interference signals from high-power charging, power changes, or different operating conditions, obtaining state deviation data. Details are as follows:

[0170] (1) Symmetrical design of detection coil: As mentioned above, the detection coil is spliced ​​together by two completely symmetrically designed and laid-out sub-coil boards on the left and right; there are a total of 64 detection coils with the same parameters on them;

[0171] (2) Detection coil pairing: Before leaving the factory, the 64 small detection coils are paired and tested for calibration, and then paired in pairs. The pairing results are as follows: 0# to 7# of the left sub-coil board are paired with 24# to 31# of the right sub-coil board respectively; 8# to 15# of the left sub-coil board are paired with 16# to 23# of the right sub-coil board respectively; 16# to 235# of the left sub-coil board are paired with 8# to 15# of the right sub-coil board respectively; 24# to 31# of the left sub-coil board are paired with 0# to 7# of the right sub-coil board respectively; and the original values ​​and deviation values ​​of each pairing coil at different power points are saved.

[0172] (3) Differential recognition algorithm:

[0173] ① Simultaneously detect the values ​​(including amplitude and phase values) of the sampling points on the two paired detection coils on the left and right sides;

[0174] ② If the values ​​of the sampling points on the two detection coils always remain at a fixed deviation value, that is, there are no metal foreign objects on the two detection coils;

[0175] ③ If the deviation value of the sampling points on the two detection coils changes, then the difference caused by the foreign object will be used to further run the scene recognition.

[0176] Step 2: Scene Type Identification: Traverse the voltage state data of all sampling points of the detection coils; the voltage state data includes voltage phase and voltage amplitude, and look for regular changes to identify the scene, as follows:

[0177] (1) Ambient temperature difference: When the ambient temperature changes, especially when the temperature difference is large, the voltage amplitude and voltage phase of each sampling point on all (or most) detection coils will change slowly and synchronously.

[0178] (2) Rain and snow cover: When the ground charging area is covered by rain and snow, the voltage amplitude of each measuring point on all (or most) detection coils is reduced; however, the voltage phase remains unchanged.

[0179] (3) Alignment: During the alignment process of the vehicle driving into the charging area along the X-axis (before it has come to a complete stop), the values ​​of all detection coil measuring points show a time-varying pattern: the voltage amplitude and voltage phase of each voltage along the Y-axis change synchronously, and the voltage amplitude and voltage phase of each voltage along the X-axis change sequentially.

[0180] Step 3, Foreign Object Detection: Combining the voltage phase and voltage amplitude of sampling points from two identical detection coils allows for more flexible and accurate identification of foreign objects. The specific identification method is as follows:

[0181] (1) Amplitude identification method: Determine whether the amplitude change exceeds the threshold.

[0182] (2) Phase recognition method: Determine whether the phase change exceeds the threshold.

[0183] (3) Combination identification method: appropriately lower the judgment threshold, combine multiple pieces of information for judgment, and complete the identification of foreign objects.

[0184] For example, if the amplitude or phase value of a signal at a certain coil measuring point changes by ≥1.0%, it is considered that there is foreign object intrusion. A combined identification method could be to also consider foreign object intrusion when the amplitude of a signal at a certain coil measuring point changes by ≥0.8% and the phase value changes by ≥0.5%; or, when the amplitude changes of signals at two adjacent coil measuring points both change by ≥0.5%, it is also considered that there is foreign object intrusion (in this case, the foreign object is very small and may be located at the junction between the two coils).

[0185] At this point, different thresholds can be set for different recognition methods based on different scenario types, so that each foreign object detection can use one of the methods in (1) to (3), or a combination of multiple methods to jointly determine whether there is a foreign object in the detection coil.

[0186] Step 4: Foreign Object Contour Recognition: Foreign object analysis is performed based on the variation patterns of the values ​​at all sampling points.

[0187] When a metallic foreign object is large, it will simultaneously and significantly affect multiple small coils. For example, multiple detection coils with signal changes may be linearly arranged, and the outline of the foreign object may be linear or cylindrical.

[0188] Step 5: Foreign Object Movement Detection: If the measuring point value shows a trend of increasing from small to large, or if the number of coils showing value changes increases or shifts in a certain direction, it is considered that a foreign object has entered. After a period of time, if the measuring point value decreases from large to small, or if the number of coils showing value changes returns to zero, it is considered that the foreign object has exited or left. If the foreign object passes by quickly, charging generally does not need to be stopped.

[0189] Therefore, by using the above methods, it is possible to accurately identify tiny metallic foreign objects such as paperclips and coins in harsh environments such as 22KW high-power charging, rain and snow cover, and drastic changes in ambient temperature, which greatly improves the stability and safety of the wireless power transmission system.

[0190] In summary, the embodiments of this application provide a device, method, and system for improving the accuracy of metal foreign object detection. Through measures such as symmetrical design of the detection coils, pairing of two coils, synchronous acquisition, and differential noise reduction, the detection of tiny metal foreign objects is achieved at low cost, especially in high-power charging and strong magnetic field interference environments, greatly improving the stability and safety of wireless power transmission systems. This is an innovative, highly practical, and excellent solution.

[0191] Below, refer to Figure 9 The following describes the execution steps of one embodiment of the processing module of this application:

[0192] S1. The processing module initializes the chips in the acquisition circuits such as FPGA, ADC, and DDS, and completes the initialization of the acquisition circuit module.

[0193] S2. The processing module configures the DDS to output two orthogonal excitation signals with the base frequency fs.

[0194] S3. Set the starting acquisition detection coil number n=0 for the left sub-coil board and the right sub-coil board, so as to determine whether the traversal detection of all detection coils has been completed based on the detection coil number.

[0195] S4. Start the acquisition of voltage status data of the detection coils of the left and right sub-coil boards. The voltage status data includes voltage amplitude and voltage phase. For details on the detection of voltage amplitude and voltage phase, please refer to the above description.

[0196] S5. Read the ADC and phase detector to obtain the voltage amplitude and voltage phase of the detection coil with coil number n.

[0197] S6. Determine if all detection coil acquisitions have been completed? If not, begin detection of the detection coils in the next pairing group, with detection coil number n = n + 1, and jump to S3.

[0198] S7. Run the differential noise reduction detection algorithm to obtain the deviation status data of each detection coil pairing group.

[0199] S8. Determine if there are foreign objects in each detection coil. If there are no foreign objects in each detection coil, then the process ends.

[0200] S9. Determine if a foreign object passes through quickly. If not, issue a warning and proceed to S10.

[0201] S10, Stop charging.

[0202] Understandably, referring to Figure 10 As shown, one embodiment of this application also provides an electronic device, including:

[0203] At least one processor 501;

[0204] At least one memory 502 is used to store at least one program that implements the above method when the at least one program is executed by at least one processor 501.

[0205] Memory 502, as a non-transitory network system, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory 502 may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory 502 may optionally include remotely located memories 502 relative to processor 501, which can be connected to processor 501 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0206] The memory 502 can be implemented as a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 502 can store the operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 502 and is called and executed by the processor 501.

[0207] The processor 501 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this application.

[0208] In some embodiments, the network device further includes:

[0209] Input / output interfaces are used to implement information input and output;

[0210] The communication interface is used to enable communication and interaction between this device and other devices. Communication can be achieved through wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0211] The bus transmits information between various components of the device (such as processor 501, memory 502, input / output interface and communication interface);

[0212] The processor 501, memory 502, input / output interface, and communication interface can communicate with each other within the device via a bus.

[0213] An embodiment of this application also provides a computer-readable storage medium storing computer-executable instructions for performing the above-described method.

[0214] An embodiment of this application also provides a computer program product, including a computer program or computer instructions stored in a computer-readable storage medium. The processor of the detection device reads the computer program or computer instructions from the computer-readable storage medium and executes the computer program or computer instructions, causing the computer device to perform the above-described method.

[0215] The system architecture and application scenarios described in this application are intended to more clearly illustrate the technical solutions of this application and do not constitute a limitation on the technical solutions provided in this application. Those skilled in the art will understand that as system architectures evolve and new application scenarios emerge, the technical solutions provided in this application are also applicable to similar technical problems.

[0216] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0217] The above description, with reference to the accompanying drawings, illustrates some embodiments of this application, but does not limit the scope of the invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and spirit of this invention should be considered within the scope of this application.

Claims

1. A method for detecting foreign objects in a wireless charging system, the wireless charging system comprising a detection coil matrix, the detection coil matrix being composed of multiple pairs of paired detection coil arrays, each detection coil having a capacitor connected to its first end, the second end of each detection coil being grounded to form a resonant circuit, and a sampling point being disposed at the capacitor away from the first end of the detection coil, the method comprising: An excitation signal is sent to each of the resonant circuits, causing the two resonant circuits corresponding to the same detection coil pairing group to be activated simultaneously. The voltage state data of each activated resonant circuit at the sampling point is obtained, wherein the voltage state data characterizes the voltage change relationship between the corresponding sampling point and time. Based on the state deviation between the two voltage state data of the same detection coil pairing group at the same time, the deviation state data of each detection coil pairing group is determined respectively. Foreign object detection data is obtained based on the voltage state data and the deviation state data.

2. The foreign object detection method for a wireless charging system according to claim 1, characterized in that, The voltage state data includes voltage amplitude and voltage phase; the step of determining the deviation state data of each detection coil pairing group based on the state deviation between two voltage state data of the same detection coil pairing group at the same time includes: The voltage deviation value is obtained by calculating the difference between the two voltage amplitudes of the same pair of detection coils at the same time. The phase deviation value is obtained by calculating the difference between the two voltage phases of the same pair of detection coils at the same time. Based on the voltage deviation value and the corresponding phase deviation value, the deviation status data of the corresponding detection coil pairing group is obtained.

3. The foreign object detection method for a wireless charging system according to claim 1, characterized in that, The step of obtaining foreign object detection data based on the voltage state data and the deviation state data includes: Based on the deviation status data, determine whether there are foreign objects within the detection range of the detection coil matrix; If the presence of a foreign object is confirmed, the foreign object scenario type is obtained; the foreign object scenario type is determined based on the voltage state data. When the foreign object scenario type indicates that foreign object detection needs to be activated, foreign object detection data is obtained based on the voltage state data.

4. The foreign object detection method for a wireless charging system according to claim 3, characterized in that, The deviation status data includes voltage deviation value and phase deviation value; determining whether there is a foreign object within the detection range of the detection coil matrix based on the deviation status data includes: Obtain the fixed voltage deviation value and fixed phase deviation value of each pair of detection coils; The voltage deviation value is compared with the corresponding fixed voltage deviation value by voltage difference, and the phase deviation value is compared with the corresponding fixed phase deviation value by phase difference; Based on the voltage difference comparison result and the phase difference comparison result, it is determined that there is a foreign object in the detection coil of the detection coil pairing group.

5. The foreign object detection method for a wireless charging system according to claim 3, characterized in that, The steps for determining the foreign object scenario type are as follows: Acquire reference voltage state change data under multiple preset foreign object scenarios; Based on the voltage state data, the actual voltage state change data of the detection coil matrix is ​​obtained; The actual voltage state change data is matched with the reference voltage state change data to obtain the foreign object scenario type.

6. The foreign object detection method for a wireless charging system according to claim 3, characterized in that, The step of obtaining foreign object detection data based on the voltage state data includes: Based on the preset foreign object characteristic threshold conditions and the voltage state data, the target detection coil containing foreign objects is determined; The outline of the foreign object is determined based on the position information of the target detection coil; Based on the voltage state data of the target detection coil, the voltage change trend of the target detection coil is determined, and the type of foreign object is determined based on the voltage change trend.

7. The foreign object detection method for a wireless charging system according to claim 6, characterized in that, The voltage state data includes voltage amplitude and voltage phase, and the foreign object characteristic threshold condition includes at least one of the following: If the voltage amplitude of the resonant circuit where the detection coil is located is greater than the first amplitude threshold, the detection coil is determined to be the target detection coil. If the voltage phase of the resonant circuit where the detection coil is located is greater than the first phase threshold, the detection coil is determined to be the target detection coil. If the voltage amplitude of the detection coil and the adjacent detection coil are both greater than the second amplitude threshold or the voltage phase is greater than the second phase threshold, the detection coil is determined to be the target detection coil.

8. A wireless charging system, comprising: The detection coil matrix consists of multiple pairs of paired detection coil arrays. Each detection coil has a capacitor connected to its first end and a grounded second end to form a resonant circuit. A sampling point is provided at the capacitor's first end away from the detection coil. The acquisition circuit module is used to send excitation signals to each of the resonant circuits and simultaneously activate two resonant circuits corresponding to the same detection coil pairing group; to perform voltage state detection on each activated resonant circuit and obtain voltage state data of each resonant circuit at the sampling point; wherein the voltage state data characterizes the voltage change relationship between the corresponding sampling point and time. The processing module is used to determine the deviation state data of each pair of detection coils based on the state deviation between the two voltage state data of the same pair of detection coils at the same time; and to obtain foreign object detection data based on the voltage state data and the deviation state data.

9. The wireless charging system according to claim 8, characterized in that, The voltage state data includes voltage amplitude and voltage phase, and the acquisition circuit module includes: A filtering and amplifying circuit is used to amplify and filter the voltage signal at the sampling point; An amplitude detection circuit is provided, which is connected to the output of the filter amplifier circuit. The amplitude detection circuit is used to detect the amplitude of the voltage signal output by the filter amplifier circuit to obtain the voltage amplitude of each sampling point. A phase detection circuit is connected to the output of the filter amplifier circuit. The phase detection circuit is used to detect the phase difference of the voltage signal output by the filter amplifier circuit to obtain the voltage phase of each sampling point.

10. The wireless charging system according to claim 9, characterized in that, The acquisition circuit module also includes: An input multiplexer is provided, wherein at least two input multiplexers are provided, the input terminal of each input multiplexer is used to input an excitation signal, and each output terminal of each input multiplexer is connected to the input terminal of one of the resonant circuits; and the two resonant circuits corresponding to the same detection coil pairing group are respectively connected to different input multiplexers; The system includes multiple output multiplexers, each input terminal of which is connected to the output terminal of a resonant circuit. Furthermore, two resonant circuits corresponding to the same pair of detection coils are connected to different output multiplexers. The output terminal of each output multiplexer is connected to the input terminal of the filter amplifier circuit.

11. The wireless charging system according to claim 9, characterized in that, The acquisition circuit module further includes an excitation signal source circuit, which is used to provide excitation signals to each of the resonant circuits and to provide phase reference signals to the phase detection circuit.

12. The wireless charging system according to claim 11, characterized in that, The excitation signal source circuit includes: A digital synthesizer that outputs two quadrature AC signals; The excitation signal processing circuit includes two circuits, each of which performs stability processing on two orthogonal AC signals. In one of the excitation signal processing circuits, the output terminal provides an excitation signal to each of the resonant circuits and a phase reference signal to the phase detection circuit; the output terminal of the other excitation signal processing circuit provides a phase reference signal to the phase detection circuit.

13. The wireless charging system according to claim 8, characterized in that, The capacitor is determined through the following steps: Obtain the coil inductance and coil resistance detection values ​​of each of the detection coils; Based on the detected values ​​of coil inductance and coil resistance of each of the detection coils, the estimated value of the quality factor of each detection coil is determined. The reference resonant frequency of the detection coil matrix is ​​determined based on the estimated quality factor of each detection coil. The measured inductance values ​​of each coil, the corresponding estimated quality factor, and the reference resonant frequency are input into a preset resonant frequency calculation formula to obtain the predicted capacitance values ​​of the capacitors on each resonant circuit. The model of the capacitor is determined based on the predicted capacitance value of each capacitor.

14. A computer-readable storage medium storing computer-executable instructions for performing the foreign object detection method of the wireless charging system according to any one of claims 1 to 7.

15. A computer program product, comprising a computer program or computer instructions, characterized in that, The computer program or the computer instructions are stored in a computer-readable storage medium. The processor of the control device reads the computer program or the computer instructions from the computer-readable storage medium and executes the computer program or the computer instructions, causing the control device to perform the foreign object detection method of the wireless charging system as described in any one of claims 1 to 7.

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