Foreign object detection method and apparatus for wireless power transfer device

Abstract

The application provides a foreign matter detection method and device of a wireless power transmission device. The method comprises: acquiring an input current of a transmitting unit of the wireless power transmission device and a temperature of a transmitting coil in the transmitting unit; determining a first current reference value corresponding to the temperature of the transmitting coil according to the temperature of the transmitting coil; and determining a foreign matter detection result according to the input current and the first current reference value corresponding to the temperature of the transmitting coil, the foreign matter detection result being used to indicate whether there is foreign matter in a transmission space of the wireless power transmission device. The embodiment of the application judges whether there is foreign matter on the transmitting coil by detecting the input current of the transmitting unit in the wireless power transmission device, and adds a temperature detection unit to adjust the current threshold value according to the coil temperature, so that more accurate foreign matter detection is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of foreign object detection, and in particular to a foreign object detection method and device for a wireless power transmission device. Background Art

[0002] In inductive wireless power transmission devices, energy is transferred between a transmitting coil and a receiving coil via an alternating magnetic field. If foreign matter (including metal or ferromagnetic materials) is present between the two coils, the alternating magnetic field can generate eddy current and hysteresis losses, leading to temperature rise and even serious safety hazards. To prevent this, a foreign object detection system is typically performed before the transmitting coil begins energy transfer. If any metallic foreign matter is detected on the transmitting coil, power transmission is prohibited.

[0003] In the related art, it is widely used to determine whether there is a metal foreign body by detecting the Q value of the transmitting coil. When calculating the Q value of the coil, it is necessary to make the resonant network (such as the resonant capacitor and the coil inductor) operate at the natural resonant frequency, and by detecting the voltage V2 at both ends of the transmitting coil and the input voltage V1 of the resonant network, the coil Q value is calculated according to Q=V2 / V1. When there is a metal foreign body near the transmitting coil, the Q value obtained by detection and calculation will decrease. Since the voltage at both ends of the transmitting coil is very high at the natural resonant frequency, it is usually necessary to adjust the input voltage of the resonant network to a smaller value. Therefore, this solution requires the design of an additional voltage regulation circuit, and it takes a long time to find the natural resonant frequency by frequency sweeping. Summary of the Invention

[0004] The present application provides a foreign object detection method and device for a wireless power transmission device to achieve a more accurate foreign object detection method with low implementation complexity and without the need to increase hardware structure.

[0005] In a first aspect, the present application provides a foreign object detection method for a wireless power transmission device, comprising:

[0006] obtaining an input current of a transmitting unit of the wireless power transmission device and a temperature of a transmitting coil in the transmitting unit;

[0007] determining, according to the temperature of the transmitting coil, a first current reference value corresponding to the temperature of the transmitting coil;

[0008] A foreign object detection result is determined according to the input current and a first current reference value corresponding to the temperature of the transmitting coil, where the foreign object detection result is used to indicate whether there is a foreign object in the transmission space of the wireless power transmission device.

[0009] In a second aspect, the present application provides a wireless power transmission device, comprising a transmitting unit, a current detection unit, a temperature detection unit and a control unit connected with the transmitting unit respectively, wherein,

[0010] The current detection unit is configured to acquire an input current of the transmitting unit.

[0011] The temperature detection unit is configured to acquire a temperature of a transmitting coil in the transmitting unit.

[0012] The control unit is configured to determine a corresponding first current reference value according to the temperature of the transmitting coil provided by the temperature detection unit, and determine a foreign object detection result according to the input current provided by the current detection unit and the first current reference value, the foreign object detection result being used to indicate whether there is a foreign object in a transmission space of the wireless power transmission device.

[0013] The foreign object detection method and device of the wireless power transmission device provided by the embodiments of the present application acquire an input current of a transmitting unit of the wireless power transmission device and a temperature of a transmitting coil in the transmitting unit, determine a first current reference value corresponding to the temperature of the transmitting coil according to the temperature of the transmitting coil, judge whether there is a foreign object in a transmission space of the wireless power transmission device by detecting the input current of the transmitting unit of the wireless power transmission device and the first current reference value corresponding to the temperature of the transmitting coil, and further determine the first current reference value corresponding to the temperature of the transmitting coil, i.e. the current threshold, according to the temperature of the transmitting coil, so that more accurate foreign object detection is realized without increasing the hardware structure. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments consistent with the present disclosure and, together with the description, further serve to explain the principles of the present disclosure.

[0015] Figure 1 is a schematic diagram of the principle of foreign object detection in the related art;

[0016] Figure 2 is a structural schematic diagram of an embodiment of the wireless power transmission device provided by the present application;

[0017] Figure 3 is a flow schematic diagram of an embodiment of the foreign object detection method of the wireless power transmission device provided by the present application;

[0018] Figure 4 is a structural schematic diagram of an embodiment of the transmitting unit provided by the present application;

[0019] Figure 5is an equivalent circuit diagram of an embodiment of a transmitting unit provided by the present application;

[0020] Figure 6 is an equivalent circuit diagram of another embodiment of the transmitting unit provided by the present application;

[0021] Figure 7 is a structural schematic diagram of another embodiment of the wireless power transmission device provided by the present application;

[0022] Figure 8 This is a schematic diagram of a specific structure of the wireless power transmission device according to an embodiment of the present application;

[0023] Figure 9 This is a schematic diagram of the intermittent operation of the transmitting unit provided in this application.

[0024] The above drawings illustrate specific embodiments of the present disclosure, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the present disclosure in any way, but rather to illustrate the concepts of the present disclosure to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0025] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0026] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0027] First, the application scenarios involved in the embodiments of the present application are introduced.

[0028] The method of the embodiment of the present application is applied to a wireless power transmission device to detect whether there is a foreign object in the transmission space of the wireless power transmission device.

[0029] In related technologies, the presence of metal foreign matter is determined by detecting the Q value of the transmitting coil in the wireless power transmission device. The Q value refers to the ratio of the inductive reactance to its equivalent loss resistance when the inductor operates under an AC voltage of a certain frequency. Figure 1As shown, when calculating the coil Q value, it is necessary to make the resonant network (such as the resonant capacitor C and the transmitting coil inductor L) operate at the natural resonant frequency By detecting the voltage V2 at both ends of the transmitting coil and the input voltage V1 of the resonant network, according to The coil Q value is calculated. The presence of metallic foreign matter reduces the calculated Q value. Because the voltage across the transmitting coil is very high in the natural resonant state, it is often necessary to adjust the input voltage of the resonant network to a lower value. Therefore, this solution requires the design of an additional voltage regulator circuit, and the time required to find the natural resonant frequency through frequency sweeping is long.

[0030] like Figure 2 As shown, the wireless power transmission device of the embodiment of the present application includes: a transmitting unit, and a current detection unit, a temperature detection unit and a control unit respectively connected to the transmitting unit, and the control unit is respectively connected to the current detection unit and the temperature detection unit.

[0031] The method of the embodiment of the present application detects the presence of a foreign object on the transmitting coil by detecting electrical parameters of the transmitting unit, such as the input current, and comparing them with the current parameters when no foreign object is present. This allows for foreign object detection without adding additional hardware.

[0032] The following specific embodiments are used to describe the technical solution of the present application in detail. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0033] Figure 3 This is a flow chart of an embodiment of a foreign body detection method for a wireless power transmission device provided by this application. Figure 3 As shown, the method provided in this embodiment includes:

[0034] Step 101: obtaining an input current of a transmitting unit of a wireless power transmission device and a temperature of a transmitting coil in the transmitting unit;

[0035] Specifically, the input current of the transmitting unit of the wireless power transmission device can be detected by the current detection unit, and the temperature of the transmitting coil in the transmitting unit can be detected by the temperature detection unit.

[0036] Step 102: Determine a first current reference value corresponding to the temperature of the transmitting coil according to the temperature of the transmitting coil.

[0037] Specifically, the control unit obtains the input current of the transmitting unit from the current detection unit, the control unit detects the temperature T of the transmitting coil through the temperature detection unit, and calculates the first current reference value I corresponding to the current temperature T ref .

[0038] Step 103: Determine a foreign object detection result based on the input current and a first current reference value corresponding to the temperature of the transmitting coil. The foreign object detection result is used to indicate whether there is a foreign object in the transmission space of the wireless power transmission device.

[0039] The foreign matter may be, for example, metallic foreign matter, magnetic material, etc.

[0040] The following describes the implementation principle of the method in the embodiment of the present application by taking the compensation circuit as a series capacitor as an example.

[0041] in, Figure 4 This is a schematic structural diagram of an embodiment of a transmitting unit provided by the present application. Figure 4 As shown, the transmitting unit includes: an inverter circuit, a resonant compensation circuit and a transmitting coil. One end of the resonant compensation circuit is connected to the inverter circuit, and the other end is connected to the transmitting coil. When there is no foreign object, the transmitting unit receives the input voltage V in and input current I in The equivalent circuit diagram of the transmitting unit is as follows Figure 5 As shown, where r is the line equivalent impedance of the inverter circuit, C is the compensation capacitor, and r L is the internal resistance of the transmitting coil, and L is the inductance of the transmitting coil.

[0042] When there is a foreign object on the transmitting coil, the alternating magnetic field will cause loss inside the metal foreign object, which is equivalent to adding a resistor r in the circuit. Fo , the equivalent circuit is as follows Figure 6 shown.

[0043] I in After low-pass filtering, the average value I can be obtained in(av) When there is a foreign object on the transmitting coil, the loss of the foreign object causes I in(av) At the same time, generally, temperature will also affect r or r L The size of I in(av) Therefore, by judging I in(av) The relationship with the preset current reference value or the current threshold determined according to the coil temperature can realize the detection of foreign objects on the transmitting coil.

[0044] The method of the embodiment obtains the input current of the transmitting unit of the wireless power transmission device and the temperature of the transmitting coil in the transmitting unit; according to the temperature of the transmitting coil, a first current reference value corresponding to the temperature of the transmitting coil is determined, and by detecting the input current of the transmitting unit of the wireless power transmission device and the first current reference value corresponding to the temperature of the transmitting coil, it is determined whether there is a foreign object in the transmission space of the wireless power transmission device. According to the temperature of the transmitting coil, the first current reference value corresponding to the temperature is determined, without increasing the hardware structure, the error caused by the temperature is eliminated, and more accurate foreign object detection is realized.

[0045] In an embodiment, step 102 can be specifically implemented in the following manner:

[0046] Obtaining a preset current reference value corresponding to a preset temperature;

[0047] According to the temperature of the transmitting coil, updating the preset current reference value to obtain a first current reference value.

[0048] Specifically, the control unit enables the inverter circuit in the transmitting unit to work at a preset frequency, so that the transmitting coil is excited. Therefore, the input current I in of the inverter circuit can be generated. The current detection unit obtains the input current and transmits it to the control unit. Further, the control unit obtains a preset temperature T initial and a preset current reference value I initial corresponding to the preset temperature T initial . And according to the temperature T of the transmitting coil, the preset current reference value I initial is updated to obtain a first current reference value I ref .

[0049] In an embodiment, updating the preset current reference value to obtain the first current reference value further specifically includes: determining a proportional coefficient; according to the proportional coefficient, the preset temperature, the preset current reference value and the temperature of the transmitting coil, the first current reference value is calculated.

[0050] Specifically, the proportional coefficient k can be set; according to the proportional coefficient k, the preset temperature T initial , the preset current reference value I initial and the temperature T of the transmitting coil, the first current reference value I ref is calculated. In an embodiment, the calculation formula of the first current reference value is:

[0051] I ref =k×(T-T initial )+I initial

[0052] It should be noted that the above formula can also be modified, and the embodiments of the present application are not limited to this.

[0053] In the above embodiment, the first current reference value is calculated by using the proportional coefficient, the preset temperature, the preset current reference value, and the temperature of the transmitting coil. This can effectively reduce or avoid the impact of ambient temperature changes on detection accuracy, and can also effectively reduce or avoid the impact of parameter tolerances on detection accuracy.

[0054] Furthermore, in some embodiments, the proportionality coefficient k may be a preset value and may be manually set in advance according to actual needs. In other embodiments, the proportionality coefficient k may be the ratio of the difference between the average values ​​of the two input currents obtained at two different temperatures to the difference between the two temperatures.

[0055] Among them, the calculation formula of the proportional coefficient k is:

[0056]

[0057] Among them, T1 and T2 are two different temperatures of the coil, I initial1 and I initial2 is the average value of the input current corresponding to two different temperatures.

[0058] For example, when the wireless power transmission device enters the calibration state, the current detection unit obtains the average value of the input current of the transmitting unit, and the temperature detection unit obtains the temperature of the transmitting coil, which are I and initial1 and T1.

[0059] Furthermore, the wireless power transmission device can be operated for a period of time to increase the temperature of the transmitting coil to another temperature T2, and the current detection unit obtains the average value I of the input current of the transmitting unit at this time. initial2 ; According to T1, T2, I initial1 , I initial2 , the proportionality coefficient k can be calculated.

[0060] In one embodiment, step 103 may be implemented as follows:

[0061] determining a current threshold value according to a first current reference value;

[0062] Obtain an average value of the input current, compare the average value of the input current with the current threshold, and determine the foreign object detection result.

[0063] If the average value of the input current is greater than the current threshold, the foreign object detection result is used to indicate that there is a foreign object in the transmission space of the wireless power transmission device.

[0064] Specifically, according to the first current reference value I refCalculate the current threshold I th For example, through I th =I ref +a or I th =I ref ×(1+b%), where a and b are preset constants.

[0065] Get the average value of the input current I in(av) , compare I in(av) and I th , determine the foreign body detection results.

[0066] If I in(av) >I th , it is determined that there is a foreign object on the transmitting coil, and the control unit terminates the operation of the inverter circuit, that is, terminates the operation of the transmitting unit.

[0067] In the above embodiment, the loss of foreign matter can be reflected by detecting the change in the average value of the input current of the inverter unit, thereby quickly determining whether there is a foreign matter, achieving low complexity and high detection accuracy.

[0068] Figure 2 This is a schematic diagram of the structure of an embodiment of the wireless power transmission device provided in this application, as shown in FIG. Figure 2 As shown, the wireless power transmission device of this embodiment includes:

[0069] An emitting unit, and a current detection unit, a temperature detection unit and a control unit respectively connected to the emitting unit, wherein the control unit is respectively connected to the current detection unit and the temperature detection unit, wherein

[0070] A current detection unit, used to obtain the input current of the transmitting unit;

[0071] A temperature detection unit, used to obtain the temperature of the transmitting coil in the transmitting unit;

[0072] The control unit is configured to determine a corresponding first current reference value based on the temperature of the transmitting coil provided by the temperature detection unit; and to determine a foreign object detection result based on the input current provided by the current detection unit and the first current reference value, wherein the foreign object detection result is used to indicate whether a foreign object is present in the transmission space of the wireless power transmission device.

[0073] The wireless power transmission device of the present embodiment detects the presence of a foreign object on the transmitting coil by detecting electrical parameters of the transmitting unit, such as input current, and comparing them with the current parameters when no foreign object is present. This enables foreign object detection without adding additional hardware.

[0074] Specifically, the control unit can detect the input current I of the transmitting unit of the wireless power transmission device through the current detection unit. inThe temperature T of the transmitting coil in the transmitting unit is detected by the temperature detection unit. Further, the temperature T of the transmitting coil is detected by the temperature detection unit, and the first current reference value I corresponding to the current temperature T is calculated by the control unit ref for determining whether there is a foreign object.

[0075] In a possible implementation, as shown in Figure 7 , the device further comprises a storage unit connected with the control unit, wherein,

[0076] The storage unit is configured to store a preset temperature and a preset current reference value corresponding to the preset temperature.

[0077] The control unit obtains the preset current reference value from the storage unit, and updates the preset current reference value according to the temperature of the transmitting coil to obtain the first current reference value.

[0078] Specifically, the control unit enables the inverter circuit in the transmitting unit to work at a preset frequency, so that the transmitting coil is excited. Therefore, the input current I in of the inverter circuit is generated. The current detection unit obtains the input current and transmits it to the control unit. The control unit obtains the preset temperature T initial and the preset current reference value I initial corresponding to the preset temperature T initial from the storage unit.

[0079] The control unit updates the preset current reference value I initial according to the temperature T of the transmitting coil detected by the temperature detection unit. Specifically, the control unit calculates the first current reference value I initial according to the proportionality coefficient k, the preset temperature T initial , the preset current reference value I ref and the temperature T of the transmitting coil. In an embodiment, the calculation formula of the first current reference value I ref is as follows:

[0080] I ref = k × (T - T initial ) + I initial

[0081] It should be noted that the above formula can also be transformed, and the embodiments of the present application do not limit this.

[0082] In the above embodiments, the first current reference value is calculated by the proportionality coefficient, the preset temperature, the preset current reference value and the temperature of the transmitting coil, which can effectively reduce or avoid the influence of the change of the environment temperature on the detection accuracy, and can effectively reduce or avoid the influence of the parameter tolerance on the detection accuracy.

[0083] The storage unit can be a non-volatile storage unit. In a possible implementation, the proportion coefficient k is also stored in the storage unit in advance. In some embodiments, the proportion coefficient is a preset value, which can be set manually according to actual needs. Specifically, the preset value can be directly written into the storage unit. In other embodiments, the proportion coefficient calculated in the actual situation is written into the storage unit through correction in a factory test.

[0084] Further, in an embodiment, as shown in Figure 8 , the current detection unit includes a low-pass filter, which is used to obtain the average value I in(av) of the input current.

[0085] The control unit determines the current threshold I th according to the first current reference value.

[0086] The average value I in(av) of the input current is compared with the current threshold to determine the foreign object detection result.

[0087] If the average value of the input current is greater than the current threshold, the foreign object detection result indicates that there is a foreign object in the transmission space of the wireless power transmission device.

[0088] Specifically, the current threshold I th is calculated. For example, it is calculated by I th = I ref + a or I th = I ref *(1+b%) where a and b are preset constants.

[0089] The average value I in(av) of the input current is obtained, and I in(av) and I th are compared to determine the foreign object detection result.

[0090] If I in(av) > I th , it is determined that there is a foreign object on the transmitting coil, and the control unit terminates the operation of the inverter circuit.

[0091] Figure 7 is a structural schematic diagram of another embodiment of the wireless power transmission device provided by the present application, as shown in Figure 7 , the device further includes an interface unit connected with the control unit, wherein

[0092] The interface unit is used to control the device to enter a correction state.

[0093] The control unit is used to obtain a current average value corresponding to a first temperature, and store the first temperature as a preset temperature and the corresponding current average value as a preset current reference value in a storage unit.

[0094] In one embodiment, the control unit is further configured to obtain an average current value corresponding to the second temperature, determine a proportionality coefficient based on the average current value corresponding to the first temperature and the average current value corresponding to the second temperature, and store the proportionality coefficient in the storage unit. The proportionality coefficient is a ratio of a difference between the average current value corresponding to the first temperature and the average current value corresponding to the second temperature to the difference between the first temperature and the second temperature.

[0095] Specifically, the interface unit may be a human-machine interface unit. An operator or tester confirms that there is no foreign matter on the transmitting coil and then operates the interface unit to put the wireless power transmission device into a calibration state. The interface unit can be operated in the following ways:

[0096] One method: pressing or releasing a mechanical button.

[0097] Another way: sending a communication instruction to the communication interface (Ethernet interface, Controller Area Network-BUS (CAN-Bus) interface, etc.) in the interface unit.

[0098] The wireless power transmission device enters the calibration state, and the current detection unit obtains the average value of the input current of the transmitting unit as the preset current reference value I initial1 The temperature detection unit obtains the first temperature T1 of the transmitting coil and uses the first temperature T1 as the preset temperature T initial , and stored in the storage unit.

[0099] Furthermore, the wireless power transmission device can be operated for a period of time to increase the temperature of the transmitting coil to another second temperature T2. The current detection unit obtains the average value of the input current of the transmitting unit at this time, that is, the current average value I corresponding to the second temperature T2. initial2 , according to T1, T2, I initial1 , I initial2 , then the proportionality coefficient k can be calculated, And write it into the storage unit.

[0100] After storage is complete, the wireless power transmission device exits the calibration state and the control unit stops enabling the inverter circuit. The calibration state can be exited automatically after the required values ​​are stored, or it can be exited by the operator or tester after operating the human-machine interface unit.

[0101] In the above embodiment, the correction function can effectively reduce or avoid the influence of parameter tolerance on detection accuracy.

[0102] Figure 8 This is a schematic diagram of a specific structure of the wireless power transmission device according to an embodiment of the present application. Figure 8 As shown, a full-bridge inverter circuit is formed by S1, S2, S3 and S4, and the input end of the inverter circuit is connected to the voltage stabilizing capacitor C in The resonant compensation circuit is electrically connected to the inverter circuit and the transmitting coil, and is used to compensate for part of the reactive power of the transmitting coil, which is used to transmit AC electromagnetic energy. Figure 8 As shown, the resonant compensation circuit is implemented using a resonant capacitor. This is not a limitation of the present invention; the resonant compensation circuit can also be implemented in other forms, such as an inductor plus capacitor. Furthermore, the inverter circuit can be a half-bridge inverter circuit or a full-bridge inverter circuit, and this invention does not limit the form of the inverter circuit.

[0103] In other embodiments, the transmitting unit may further include a transformer, which realizes voltage conversion. The transformer may be arranged before or after the inverter circuit.

[0104] In some embodiments, when performing foreign object detection, the control unit sets the operating frequency of the inverter circuit to a preset frequency, wherein the preset frequency is greater than the natural resonant frequency. Among them, L is the inductance of the transmitting coil and C is the resonant capacitance.

[0105] In the embodiment of the present application, the operating frequency of the inverter current is greater than the natural resonant frequency. When there is a foreign object on the coil, the resonant current remains almost unchanged, the inherent loss of the transmitting unit remains unchanged, and detecting the change in the input current of the inverter circuit can reflect the presence of foreign matter, with high detection accuracy.

[0106] Furthermore, in some embodiments, during the foreign object detection phase, the control unit controls the inverter circuit to operate intermittently. Specifically, during the foreign object detection phase, if no foreign object is detected, the inverter circuit is enabled, which means that the power is continuously consumed. Therefore, the control unit may optionally enable the inverter circuit to operate intermittently, such as Figure 9 As shown, foreign object detection is performed only in the enabled phase, and the inverter circuit is stopped in the disabled phase, thereby reducing losses.

[0107] The device of this embodiment can be used to execute the technical solution of the above method embodiment. Its implementation principle and technical effects are similar and will not be repeated here.

[0108] A computer-readable storage medium is also provided in an embodiment of the present application, on which a computer program is stored. When the computer program is executed by a control unit, the corresponding method in the aforementioned method embodiment is implemented. The specific implementation process can be found in the aforementioned method embodiment. The implementation principle and technical effects are similar and will not be repeated here.

[0109] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the following claims.

[0110] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A foreign body detection method for a wireless power transmission device, characterized in that: include: obtaining an input current of a transmitting unit of the wireless power transmission device and a temperature of a transmitting coil in the transmitting unit; determining, according to the temperature of the transmitting coil, a first current reference value corresponding to the temperature of the transmitting coil; determining a foreign object detection result based on the input current and a first current reference value corresponding to the temperature of the transmitting coil, wherein the foreign object detection result is used to indicate whether there is a foreign object in the transmission space of the wireless power transmission device; The determining the foreign object detection result according to the input current and a first current reference value corresponding to the temperature of the transmitting coil includes: determining a current threshold according to the first current reference value; An average value of the input current is obtained, and the average value of the input current is compared with the current threshold to determine the foreign object detection result.

2. The method according to claim 1, characterized in that The determining, according to the temperature of the transmitting coil, a first current reference value corresponding to the temperature of the transmitting coil includes: Obtaining a preset current reference value corresponding to a preset temperature; The preset current reference value is updated according to the temperature of the transmitting coil to obtain the first current reference value.

3. The method according to claim 2, characterized in that The updating of the preset current reference value according to the temperature of the transmitting coil to obtain a first current reference value corresponding to the temperature of the transmitting coil includes: Determine the proportionality factor; The first current reference value is calculated according to the proportional coefficient, the preset temperature, the preset current reference value, and the temperature of the transmitting coil.

4. The method according to claim 3, characterized in that The calculation formula of the first current reference value is: in, is the first current reference value, is the preset current reference value, is the proportionality coefficient, is the preset temperature, is the temperature of the transmitting coil.

5. The method according to claim 3, characterized in that The proportionality coefficient is the ratio of the difference between the average values ​​of the two input currents obtained at two different temperatures to the difference between the two temperatures.

6. The method according to claim 1, characterized in that The comparing the average value of the input current with the current threshold to determine the foreign object detection result includes: If the average value of the input current is greater than the current threshold, the foreign object detection result is used to indicate that a foreign object exists in the transmission space of the wireless power transmission device.

7. A wireless power transmission device, characterized in that: It includes a transmitting unit, and a current detection unit, a temperature detection unit and a control unit respectively connected to the transmitting unit, wherein the control unit is respectively connected to the current detection unit and the temperature detection unit, wherein: The current detection unit is used to obtain the input current of the transmitting unit; The temperature detection unit is used to obtain the temperature of the transmitting coil in the transmitting unit; The control unit is configured to determine a corresponding first current reference value based on the temperature of the transmitting coil provided by the temperature detection unit; and determine a foreign object detection result based on the input current provided by the current detection unit and the first current reference value, wherein the foreign object detection result is used to indicate whether there is a foreign object in the transmission space of the wireless power transmission device; The current detection unit includes a low-pass filter for obtaining the average value of the input current; The control unit determines a current threshold value according to the first current reference value; The average value of the input current is compared with the current threshold to determine the foreign object detection result.

8. The device according to claim 7, characterized in that It also includes a storage unit, which is connected to the control unit, wherein: The storage unit is used to store a preset temperature and a preset current reference value corresponding to the preset temperature; The control unit obtains the preset current reference value from the storage unit, and updates the preset current reference value according to the temperature of the transmitting coil to obtain the first current reference value.

9. The device according to claim 8, characterized in that The storage unit is further used to store the proportional coefficient; The control unit obtains the proportional coefficient from the storage unit, and calculates the first current reference value according to the proportional coefficient, the preset temperature, the preset current reference value, and the temperature of the transmitting coil.

10. The device according to claim 9, characterized in that The calculation formula of the first current reference value is: in, is the first current reference value, is the preset current reference value, is the proportionality coefficient, is the preset temperature, is the temperature of the transmitting coil.

11. The device according to claim 10, characterized in that The proportionality coefficient is the ratio of the difference between the two average values ​​of the input currents obtained at two different temperatures to the difference between the two temperatures.

12. The device according to claim 7, characterized in that If the average value of the input current is greater than the current threshold, the foreign object detection result is used to indicate that a foreign object exists in the transmission space of the wireless power transmission device.

13. The device according to any one of claims 9 to 11, characterized in that It also includes an interface unit, which is connected to the control unit, wherein: The interface unit is used to control the device to enter a calibration state; The control unit is configured to obtain a current average value corresponding to a first temperature, and store the first temperature as a preset temperature and the corresponding current average value as the preset current reference value in the storage unit.

14. The device according to claim 13, characterized in that The control unit is further configured to obtain an average current value corresponding to the second temperature, determine the proportional coefficient based on the average current value corresponding to the first temperature and the average current value corresponding to the second temperature, and store the proportional coefficient in the storage unit.

15. The device according to claim 14, characterized in that The proportionality coefficient is a ratio of a difference between an average current value corresponding to the first temperature and an average current value corresponding to the second temperature to a difference between the first temperature and the second temperature.

16. The device according to claim 7, characterized in that The transmitting unit includes: an inverter circuit, a resonance compensation circuit, and the transmitting coil connected in sequence, wherein the inverter circuit is connected to the current detection unit and the control unit respectively; wherein the control unit controls the inverter circuit to convert input direct current power into alternating current power, and transmits the alternating current power through the transmitting coil.

17. The device according to claim 16, characterized in that When detecting the input current of the transmitting unit, the control unit controls the operating frequency of the inverter circuit to be a preset frequency, and the preset frequency is greater than the resonant frequency.

18. The device according to claim 16, characterized in that During the foreign object detection phase, the control unit controls the inverter circuit to operate intermittently.

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