A wireless charging foreign object detection system and method based on third harmonic component

Abstract

The application discloses a wireless charging foreign matter detection system and method based on a third harmonic component, and comprises the following steps: S1, constructing a transmitting end and a receiving end, and constructing a double-frequency channel of a transmitting fundamental frequency and a transmitting third-order frequency in the transmitting end; S2, constructing a resonance parameter of the double-frequency channel of the transmitting end, and realizing double-frequency signal transmission; S3, constructing a double-frequency channel of a receiving fundamental frequency and a receiving third-order frequency in the receiving end; the receiving fundamental frequency channel is used for realizing power transmission; and the receiving third-order frequency channel is used for blocking the third-order harmonic component from the transmitting coil; S4, constructing an impedance detection model in an upper computer, and used for detecting the impedance of the transmitting coil in the transmitting end in real time; and S5, starting the system to work, and comparing the real-time impedance with a preset impedance in the upper computer, and issuing an alarm when the preset threshold is exceeded. The first third harmonic filter circuit is arranged in the transmitting end, and whether there is foreign matter is distinguished by detecting the impedance change of the transmitting coil.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless charging safety technology, and particularly relates to a wireless charging foreign matter detection system and method based on third harmonic component. BACKGROUND

[0002] In recent years, wireless charging technology has been promoted and applied in many fields due to its safety, speed and convenience. The wireless charging system uses a high-frequency alternating magnetic field to realize non-contact transmission of electric energy. However, because there is a gap between the transmitting coil and the receiving coil, in actual application, there is a situation where foreign matter enters the gap. If the foreign matter is a metal object, on the one hand, it will increase the system loss and affect the transmission efficiency; on the other hand, due to the eddy current effect, the temperature of the metal foreign matter will rise, which poses a great threat to the system safety, so the foreign matter detection technology is very critical.

[0003] At present, the foreign matter detection schemes for wireless charging systems can be divided into the following three types according to the different detection principles and implementation means: detection schemes based on system parameters of the primary and secondary sides, detection schemes adding detection coils, and detection schemes adding cameras, ultrasonic waves and other auxiliary sensors.

[0004] 1. The detection method based on the system parameters of the primary and secondary sides does not need additional detection coils and complex signal processing circuits, but for a large-power wireless charging system, the power itself will have certain fluctuations, so it is not sensitive to foreign matter and has a high probability of false positives, and can only be applied to small and medium-sized power systems.

[0005] 2. The method of adding detection coils mainly uses detection coils to extract foreign matter information, which has low implementation cost and high detection precision, and is currently widely used. However, the detection coil itself is coupled with the primary and secondary coil of the wireless charging system, which will also affect the system, so it is necessary to overcome the noise interference from the primary coil, the complex electromagnetic environment outside and the detection system itself, and the design of the signal processing circuit has high requirements. In order to eliminate the detection blind area and improve the range and sensitivity of the detection, this type of scheme usually increases the number of layers or turns of the detection coil, which increases the coupling degree between the detection coil and the primary and secondary coils of the system, and further increases the system design difficulty. At the same time, due to the increase of the number of layers and the area of the coil, the detection system will further occupy the space of the original system. In addition, the detection range of foreign matter is concentrated in the area covered by the detection coil, and it is difficult to detect the surrounding range of the charging system, so this type of scheme has poor implementation effect in some occasions where the detection range requirement is high.

[0006] 3. The detection method of adding cameras, ultrasonic waves and other auxiliary sensors needs to consider many environmental problems, and the cost of the sensor itself is high, which is suitable for occasions with high precision requirements. SUMMARY

[0007] In order to solve the problem of low foreign matter detection efficiency in the prior art wireless charging system, the application provides a wireless charging foreign matter detection system and method based on third harmonic component, which can accurately identify metal foreign matter and improve detection efficiency while reducing cost by setting a third harmonic filter circuit at the transmitting end without adding additional detection coils or sensors.

[0008] In order to achieve the above-mentioned purpose, the application provides the following technical solutions:

[0009] 1. A wireless charging foreign matter detection system based on third harmonic component, comprising a transmitting end, a receiving end, an impedance detection module and an upper computer; the transmitting end and the receiving end are wirelessly connected, and the transmitting end is connected with the upper computer through the impedance detection module;

[0010] The impedance detection module detects the impedance of the transmitting end in real time and sends it to the upper computer for storage and analysis; when foreign matter enters the gap between the transmitting end and the receiving end, if the impedance of the transmitting end exceeds a preset threshold, the upper computer will issue an alarm and stop wireless charging.

[0011] Preferably, the transmitting end comprises a transmitting coil Lp, a first third harmonic filter circuit, and a first tuning capacitor Cp, the first third harmonic filter circuit comprises a first inductor La, a first adjustable capacitor Caa, and a first capacitor Ca.

[0012] Preferably, the specific circuit of the transmitting end is as follows:

[0013] One end of the power supply voltage is connected with one end of the first tuning capacitor Cp, and the other end of the first tuning capacitor Cp and the other end of the first adjustable capacitor Caa are connected in parallel with one end of the transmitting coil Lp.

[0014] The other end of the power supply voltage is connected with one end of the first inductor La and one end of the first capacitor Ca respectively, the other end of the first inductor La is connected with one end of the first adjustable capacitor Caa, and the other end of the first capacitor Ca is connected with the other end of the transmitting coil Lp.

[0015] Preferably, the receiving end comprises a load RL, a receiving coil Ls, a second third harmonic filter circuit, and a second tuning capacitor Cs; the second third harmonic filter circuit comprises a second inductor Lb, a second adjustable capacitor Cbb, and a second capacitor Cb.

[0016] Preferably, the specific circuit of the receiving coil is as follows:

[0017] One end of the receiving coil Ls is connected with one end of the second tuning capacitor Cs, and the other end of the second tuning capacitor Cs and the other end of the second adjustable capacitor Cbb are connected in parallel with one end of the load RL.

[0018] The other end of the receiving coil Ls is connected with one end of the second inductor Lb and one end of the second capacitor Cb respectively, the other end of the second inductor Lb is connected with one end of the second adjustable capacitor Cbb, and the other end of the second capacitor Cb is connected with the other end of the load RL.

[0019] The application also provides a wireless charging foreign matter detection method based on third harmonic components, comprising the following steps:

[0020] S1: constructing a transmitting end and a receiving end, and constructing a double-frequency channel of a transmitting fundamental frequency and a transmitting third-order frequency at the transmitting end;

[0021] S2: constructing a resonance parameter of the double-frequency channel of the transmitting end to realize double-frequency signal transmission;

[0022] S3: constructing a double-frequency channel of a receiving fundamental frequency and a receiving third-order frequency at the receiving end: the receiving fundamental frequency channel is used for realizing power transmission; and the receiving third-order frequency channel is used for blocking third harmonic components from the transmitting coil;

[0023] S4: constructing an impedance detection model in an upper computer, which is used for detecting the impedance of the transmitting coil in the transmitting end in real time;

[0024] S5: the system starts to work, the impedance of the transmitting coil is detected in real time, and the upper computer compares the real-time impedance with a preset impedance, and sends an alarm when the preset threshold is exceeded.

[0025] Preferably, in S2, the resonance parameter of the double-frequency channel of the transmitting end satisfies the following equation:

[0026]

[0027] In formula (1), j represents an imaginary part; ω1 represents a fundamental frequency; ω3 represents a third-order frequency; C aa represents a first adjustable capacitor; L a represents a first inductor; C a represents a first capacitor; C p represents a first tuning capacitor.

[0028] Preferably, the relationship between the fundamental frequency ω1 and the third-order frequency ω3 is as follows:

[0029] ω3=3ω1.

[0030] Preferably, in S3, the parameter values of the receiving fundamental frequency and the receiving third-order frequency of the receiving end satisfy the following equation:

[0031]

[0032] In formula (2), j represents an imaginary part; ω1 represents a fundamental frequency; ω3 represents a third-order frequency; C bb represents a second adjustable capacitor; Lb represents the second inductance; C b represents the second capacitance; C s represents the second tuning capacitance.

[0033] Preferably, in the S4, the impedance detection model of the transmitting coil is:

[0034]

[0035] In formula (3), Z Tx represents the impedance of the transmitting coil; j represents the imaginary part; ω represents the system operating frequency; ω1 represents the fundamental frequency; C aa represents the first adjustable capacitance; R a represents the equivalent internal resistance of the first inductance; L a represents the first inductance; C a represents the first capacitance; C p represents the first tuning capacitance; R p represents the equivalent internal resistance of the transmitting coil.

[0036] In summary, compared with the prior art, the present application has at least the following beneficial effects:

[0037] The present application sets a first third harmonic filter circuit at the transmitting end, and distinguishes whether there is a foreign matter by detecting the impedance change of the transmitting coil. In the case of metal foreign matter, the amplitude of the impedance is significantly increased. When this change is monitored, the information is extracted and uploaded to the host computer, an alarm signal is sent and the charging is stopped, so as to realize accurate discrimination of the foreign matter.

[0038] The second third harmonic filter circuit is also set at the receiving end, so that the receiving coil is tuned at the third order frequency, but the third order current is filtered by the filter. Therefore, the existence of metal foreign matter and the misalignment of the receiving coil are uniquely identified, and the foreign matter detection accuracy is improved. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a schematic diagram of a wireless charging foreign matter detection system based on a third harmonic component according to an exemplary embodiment of the present application.

[0040] Figure 2 It is a schematic diagram of a transmitting end and a receiving end circuit according to an exemplary embodiment of the present application.

[0041] Figure 3 It is a schematic diagram of a wireless charging foreign matter detection method based on a third harmonic component according to an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0042] The application will be described in further detail below with reference to the embodiments and specific working examples. However, it should not be understood that the scope of the above-mentioned subject matter of the application is limited to the following examples, and any technology achieved based on the content of the application falls within the scope of the application.

[0043] In the description of the application, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0044] As shown in Figure 1 The application provides a wireless charging foreign object detection system based on third harmonic component, which comprises a transmitting end, a receiving end, an impedance detection module and a host computer. The transmitting end and the receiving end are wirelessly connected, and the transmitting end is connected with the host computer through the impedance detection module.

[0045] In this embodiment, the impedance detection module detects the impedance of the transmitting end in real time and sends it to the host computer for storage and analysis. When a foreign object (such as a metal foreign object Mo) enters the gap between the transmitting end and the receiving end, the impedance of the transmitting end will change (for example, increase), and if it exceeds the preset threshold, the host computer will issue an alarm and stop the wireless charging, thereby avoiding the interference of the foreign object on the charging system.

[0046] As shown in Figure 2 The transmitting end comprises a transmitting coil Lp (the internal resistance of the transmitting coil is equivalent to Rp), a first third harmonic filter circuit, and a first tuning capacitor Cp. The first third harmonic filter circuit comprises a first inductor La (the internal resistance is equivalent to Ra), a first adjustable capacitor Caa, and a first capacitor Ca.

[0047] One end of the power supply voltage U is connected with one end of the first tuning capacitor Cp, and the other end of the first tuning capacitor Cp and the other end of the first adjustable capacitor Caa are connected in parallel and then connected with one end of the transmitting coil Lp.

[0048] The other end of the power supply voltage U is connected with one end of the first inductor La and one end of the first capacitor Ca respectively, the other end of the first inductor La is connected with one end of the first adjustable capacitor Caa, and the other end of the first capacitor Ca is connected with the other end of the transmitting coil Lp.

[0049] In this embodiment, the first adjustable capacitor Caa is used to adjust the value of the first capacitor Ca according to the actual frequency change to achieve the purpose of resonance filtering.

[0050] The receiving end comprises a load RL, a receiving coil Ls (the internal resistance of the receiving coil is equivalent to Rs), a second third harmonic filter circuit, a second tuning capacitor Cs, and the second third harmonic filter circuit comprises a second inductor Lb (the internal resistance is equivalent to Rb), a second adjustable capacitor Cbb, and a second capacitor Cb:

[0051] One end of the receiving coil Ls is connected to one end of the second tuning capacitor Cs, and the other end of the second tuning capacitor Cs and the other end of the second adjustable capacitor Cbb are connected in parallel to one end of the load RL;

[0052] The other end of the receiving coil Ls is respectively connected to one end of the second inductor Lb and one end of the second capacitor Cb, the other end of the second inductor Lb is connected to one end of the second adjustable capacitor Cbb, and the other end of the second capacitor Cb is connected to the other end of the load RL.

[0053] In the embodiment, the second adjustable capacitor Cbb is used to adjust the value of the second capacitor Cb according to the change of the actual frequency to achieve the purpose of resonance filtering.

[0054] The circuit topology of the patent is different from that in other documents, for example, the fifth harmonic circuit adopts a series wave suppression network, while the application adopts a short-circuit high-order harmonic design of the circuit topology and implementation scheme

[0055] The application adopts the first adjustable capacitor and the second adjustable capacitor, which can not only realize flexible harmonic order adjustment, but also can perform resonance filtering through dynamic adjustment of the first adjustable capacitor and the second adjustable capacitor in the case of offset of the coupling mechanism and the like, so as to distinguish the impedance characteristic change caused by the foreign matter from the impedance characteristic change caused by the offset of the coupling mechanism, thereby improving the detection precision.

[0056] Based on the above system, as shown in the figure, Figure 3 The application provides a wireless charging foreign matter detection method based on a third harmonic component, comprising the following steps:

[0057] S1: Construct the transmitting end and the receiving end of the above system, and construct a double-frequency channel of a fundamental frequency and a third-order frequency in the transmitting end.

[0058] In the embodiment, the system operating frequency can be converted into the fundamental frequency and the third-order frequency through Fourier transform; the fundamental frequency is used for wireless power transmission, and the third-order frequency is used for detecting foreign matters such as metal foreign matters Mo.

[0059] S2: Construct the resonance parameters of the double-frequency channel of the transmitting end to ensure effective power transmission, and also improve the metal foreign matter detection performance.

[0060] In this embodiment, since the equivalent series resistance of the transmitting coil and the first inductor in the transmitting end is much smaller than its reactance, the equivalent resistance is ignored, and the resonance parameters of the dual-frequency channel are constructed, which should satisfy the following equation:

[0061]

[0062] In formula (1), j represents the imaginary part; ω1 represents the fundamental frequency; ω3 represents the third-order frequency; C aa represents the first adjustable capacitor; L a represents the first inductor; C a represents the first capacitor; C p represents the first tuning capacitor.

[0063] In this embodiment, in order to ensure not only effective power transmission but also improve the metal foreign object detection performance of the two frequencies, the two frequencies should satisfy:

[0064] ω3 = 3ω1.

[0065] S3: The receiving end also constructs a dual-frequency channel of the fundamental frequency and the third-order frequency: the fundamental frequency channel is used to realize power transmission; the third-order frequency channel is used to block the third-order harmonic components from the transmitting coil and distinguish itself from metal foreign objects.

[0066] The parameter values of the receiving end should satisfy the following equation:

[0067]

[0068] In formula (2), j represents the imaginary part; ω1 represents the fundamental frequency; ω3 represents the third-order frequency; C bb represents the second adjustable capacitor; L b represents the second inductor; C b represents the second capacitor; C s represents the second tuning capacitor.

[0069] In this way, the receiving coil is also tuned at the third-order frequency, but the third-order current is filtered by the filter, so the presence of metal foreign objects and the misalignment of the receiving coil are uniquely identified. At the same time, the transmitting coil does not affect the system input impedance at the third-order frequency, ensuring the unique response to the presence of metal foreign objects.

[0070] S4: An impedance detection model is constructed in the upper computer for real-time detection of the impedance of the transmitting coil in the transmitting end:

[0071]

[0072] In formula (3), Z Tx represents the impedance of the transmitting coil; j represents the imaginary part; ω represents the system operating frequency; ω1 represents the fundamental frequency; C aarepresents the first adjustable capacitor; R a represents the equivalent internal resistance of the first inductor; L a represents the first inductor; C a represents the first capacitor; C p represents the first tuning capacitor; R p represents the equivalent internal resistance of the transmitting coil.

[0073] S5: The system starts to work, and the impedance of the transmitting coil is detected in real time. The host computer compares the real-time impedance with the preset impedance, and when the preset threshold is exceeded, an alarm is sent so that the staff can clearly identify the foreign matter.

[0074] In this embodiment, the impedance of the transmitting coil changes with the frequency, so the real-time impedance should be compared with the preset impedance at the same frequency to improve accuracy.

[0075] Those skilled in the art can understand that the above-mentioned embodiments are specific embodiments for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. A method for detecting foreign objects in wireless charging based on the third harmonic component, applied to a wireless charging foreign object detection system, wherein the wireless charging foreign object detection system includes a transmitter, a receiver, an impedance detection module, and a host computer; the transmitter and the receiver are wirelessly connected, and the transmitter is connected to the host computer through the impedance detection module; The impedance detection module detects the transmitter impedance in real time and sends it to the host computer for storage and analysis. When a foreign object enters the gap between the transmitter and receiver, if the transmitter impedance exceeds a preset threshold, the host computer will issue an alarm and stop wireless charging. The transmitting end includes a transmitting coil (Lp), a first third harmonic filter circuit, and a first tuning capacitor (Cp). The first third harmonic filter circuit includes a first inductor (La), a first adjustable capacitor (Caa), and a first capacitor (Ca). The receiving end includes a load (RL), a receiving coil (Ls), a second third harmonic filter circuit, and a second tuning capacitor (Cs). The second third harmonic filter circuit includes a second inductor (Lb), a second adjustable capacitor (Cbb), and a second capacitor (Cb). Its features are, The wireless charging foreign object detection method based on the third harmonic component includes the following steps: S1: Construct a transmitter and a receiver. At the transmitter, construct a dual-frequency channel with a base frequency and a third-order frequency. S2: Construct the resonant parameters of the dual-frequency channel at the transmitting end to realize dual-frequency signal transmission; S3: Construct a dual-frequency channel at the receiving end, consisting of a base frequency channel and a third-order frequency channel: the base frequency channel is used for power transmission; the third-order frequency channel is used to block the third-order harmonic components from the transmitting coil. S4: Construct an impedance detection model in the host computer to detect the impedance of the transmitting coil in the transmitter in real time; S5: The system starts working and detects the impedance of the transmitting coil in real time. The host computer compares the real-time impedance with the preset impedance. When the preset threshold is exceeded, an alarm is issued. In S2, the resonant parameters of the dual-frequency channel at the transmitting end satisfy the following equation: In formula (1), j represents the imaginary part; Indicates the fundamental frequency; Indicates the third-order frequency; This indicates the first adjustable capacitor; Indicates the first inductance; Indicates the first capacitor; Indicates the first tuning capacitor; In step S3, the parameter values ​​of the receiving fundamental frequency and the receiving third-order frequency at the receiving end satisfy the following equation: In formula (2), j represents the imaginary part; Indicates the fundamental frequency; Indicates the third-order frequency; This indicates the second adjustable capacitor; Indicates the second inductor; Indicates the second capacitor; This indicates the second tuning capacitor.

2. The wireless charging foreign object detection method based on the third harmonic component as described in claim 1, characterized in that, The specific circuit of the transmitter is as follows: One end of the power supply voltage is connected to one end of the first tuning capacitor (Cp), and the other end of the first tuning capacitor (Cp) and the other end of the first adjustable capacitor (Caa) are connected in parallel to one end of the transmitting coil (Lp). The other end of the power supply voltage is connected to one end of the first inductor (La) and one end of the first capacitor (Ca), the other end of the first inductor (La) is connected to one end of the first adjustable capacitor (Caa), and the other end of the first capacitor (Ca) is connected to the other end of the transmitting coil (Lp).

3. The wireless charging foreign object detection method based on the third harmonic component as described in claim 1, characterized in that, The specific circuit of the receiving coil is as follows: One end of the receiving coil (Ls) is connected to one end of the second tuning capacitor (Cs), and the other end of the second tuning capacitor (Cs) and the other end of the second adjustable capacitor (Cbb) are connected in parallel and then connected to one end of the load (RL). The other end of the receiving coil (Ls) is connected to one end of the second inductor (Lb) and one end of the second capacitor (Cb), respectively. The other end of the second inductor (Lb) is connected to one end of the second adjustable capacitor (Cbb), and the other end of the second capacitor (Cb) is connected to the other end of the load (RL).

4. The wireless charging foreign object detection method based on the third harmonic component as described in claim 1, characterized in that, The fundamental frequency and third-order frequency The relationship is: 。 5. The wireless charging foreign object detection method based on the third harmonic component as described in claim 1, characterized in that, In S4, the impedance detection model of the transmitting coil is as follows: In formula (3), The impedance of the transmitting coil is represented by ; j represents the imaginary part. Indicates the system operating frequency; Indicates the fundamental frequency; This indicates the first adjustable capacitor; This represents the equivalent internal resistance of the first inductor; Indicates the first inductance; Indicates the first capacitor; Indicates the first tuning capacitor; This represents the equivalent internal resistance of the transmitting coil.

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