WO2021179784A1 - 一种无线充电异物检测方法和装置 - Google Patents

一种无线充电异物检测方法和装置 Download PDF

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Publication number
WO2021179784A1
WO2021179784A1 PCT/CN2021/070779 CN2021070779W WO2021179784A1 WO 2021179784 A1 WO2021179784 A1 WO 2021179784A1 CN 2021070779 W CN2021070779 W CN 2021070779W WO 2021179784 A1 WO2021179784 A1 WO 2021179784A1
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frequency
difference
impedance
voltage
resonant
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PCT/CN2021/070779
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English (en)
French (fr)
Inventor
陈双全
武志贤
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华为技术有限公司
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Publication of WO2021179784A1 publication Critical patent/WO2021179784A1/zh

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/10—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles characterised by the energy transfer between the charging station and the vehicle
    • B60L53/12—Inductive energy transfer
    • B60L53/124—Detection or removal of foreign bodies
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/60—Circuit arrangements or systems for wireless supply or distribution of electric power responsive to the presence of foreign objects, e.g. detection of living beings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/14—Plug-in electric vehicles

Definitions

  • This application relates to the field of wireless charging technology, and in particular to a method and device for detecting foreign objects in wireless charging.
  • the two technical solutions of magnetic induction coupling and resonance coupling are the most widely used. Both of these technical solutions are based on the principle of electromagnetic induction.
  • a high-frequency magnetic field is generated by the high-frequency alternating current of the transmitting coil, and the energy is transmitted from the transmitting coil to the receiving coil through the high-frequency magnetic field to realize wireless charging.
  • the usual wireless charging system consists of a power transmitting device connected to the mains and a power receiving device connected to the load. There is no electrical contact between the power transmitting device and the power receiving device, and wireless energy transmission is performed through electromagnetic induction.
  • the induced voltage method is commonly used for foreign object detection.
  • the principle of the induced voltage method is to place the detection circuit in a high-frequency magnetic field, and determine whether the magnetic field is distorted by judging whether the induced voltage of the detection circuit is abnormal, and then whether there is a foreign body.
  • the existing wireless charging detection methods have insufficient detection accuracy and are prone to misjudgment.
  • the present application discloses a wireless charging foreign body detection method and device, which are used to solve the disadvantages of insufficient accuracy of the foreign body detection method and device in the prior art and easy misjudgment.
  • the first aspect of the present application provides a foreign object detection method used in a wireless charging system, the method including:
  • the first difference voltage is the difference between the first preset voltage and the first input voltage.
  • the resonance network is in the The input voltage at the first frequency;
  • the second difference voltage is the difference between the second preset voltage and the second input voltage.
  • the resonance network is in the The input voltage at the second frequency;
  • the foreign body detection method provided in the first aspect of the present application can improve the accuracy of foreign body detection and reduce misjudgments.
  • the judging whether there is a foreign object according to the third difference voltage specifically includes:
  • determining the actual resonant frequency of the resonant network can effectively improve the accuracy of foreign object detection.
  • the method before determining the first frequency and the second frequency, the method further include:
  • Determining the actual resonant frequency of the resonant network specifically includes:
  • the frequency of the resonant network is swept, and it is measured that the frequency corresponding to the maximum input voltage of the resonant network is the actual resonant frequency of the resonant network.
  • the first frequency is in the frequency range [(f- ⁇ f), f ] Is selected
  • the second frequency is selected in the frequency interval [f, (f+ ⁇ f)]
  • the f is the actual resonance frequency of the resonant network
  • the value interval of the ⁇ f is [0.01f, 0.5 f].
  • the resonant network includes N detection coils, and N is greater than or equal to 1. Integer.
  • multiple detection coils can increase the coverage area of foreign object detection.
  • any one of the N detection coils includes a switch, an inductance element And a capacitive element, the switch is connected in series with the inductive element, and the capacitive element is connected in parallel with the inductive element.
  • a method for detecting foreign objects in wireless charging includes:
  • the first difference impedance is the difference between the first input impedance and a first preset impedance.
  • the resonance network is in the Input impedance at the first frequency;
  • the second difference impedance is the difference between the second input impedance and a second preset impedance.
  • the resonance network is in the Input impedance at the second frequency;
  • the foreign body detection method provided in the second aspect of the present application can improve the accuracy of foreign body detection and reduce misjudgments.
  • the judging whether there is a foreign object according to the third difference impedance specifically includes:
  • determining the actual resonant frequency of the resonant network can effectively improve the accuracy of foreign object detection.
  • the method before determining the first frequency and the second frequency, the method further include:
  • Determining the actual resonant frequency of the resonant network specifically includes:
  • the frequency of the resonant network is swept, and it is measured that the frequency corresponding to the maximum input voltage of the resonant network is the actual resonant frequency of the resonant network.
  • the first frequency is in the frequency range [(f- ⁇ f), f ] Is selected
  • the second frequency is selected in the frequency interval [f, (f+ ⁇ f)]
  • the f is the actual resonance frequency of the resonant network
  • the value interval of the ⁇ f is [0.01f, 0.5 f].
  • the resonant network includes N detection coils, and N is greater than or equal to 1. Integer.
  • multiple detection coils can increase the coverage area of foreign object detection.
  • any one of the N detection coils includes a switch, an inductance element And a capacitive element, the switch is connected in series with the inductive element, and the capacitive element is connected in parallel with the inductive element.
  • a third aspect of the present application provides a wireless charging foreign object detection device, the device includes an AC source, a resonance network, a measurement circuit and a controller, wherein:
  • the AC source is used to provide AC incentives
  • the resonance network is used to detect whether there is a foreign object between the wireless charging transmitting device and the receiving device;
  • the measurement circuit is used to measure the input voltage of the resonance network
  • the controller is configured to determine a first frequency and a second frequency, the first frequency is less than the actual resonant frequency of the resonant network, and the second frequency is greater than the actual resonant frequency of the resonant network;
  • the first difference voltage is the difference between the first preset voltage and the first input voltage.
  • the resonance network is in the The input voltage at the first frequency;
  • the second difference voltage is the difference between the second preset voltage and the second input voltage.
  • the resonance network is in the The input voltage at the second frequency;
  • a third difference voltage is calculated, and the third difference voltage is the absolute value of the voltage difference between the first difference voltage and the second difference voltage.
  • the foreign body detection device provided in the third aspect of the present application can improve the accuracy of foreign body detection and reduce misjudgments.
  • the AC source includes a constant AC source.
  • the constant AC source in the first possible implementation of the third aspect of the present application can improve the stability of the foreign object detection device.
  • the resonant network includes N detection coils, and N is an integer greater than or equal to 1.
  • multiple detection coils can increase the coverage area of foreign object detection.
  • any one of the N detection coils includes a switch, an inductor The element and the capacitive element, the switch is connected in series with the inductive element, and the capacitive element is connected in parallel with the inductive element.
  • the measurement circuit is further used for:
  • the controller is further configured to:
  • the first frequency is less than the actual resonant frequency of the resonant network, and the second frequency is greater than the actual resonant frequency of the resonant network;
  • the first difference impedance is the difference between the first input impedance and a first preset impedance.
  • the resonance network is in the Input impedance at the first frequency;
  • the second difference impedance is the difference between the second input impedance and a second preset impedance.
  • the resonance network is in the Input impedance at the second frequency;
  • the foreign object detection device further includes an alarm, and the alarm is used for:
  • the controller determines that there is a foreign object, it alarms, or a switch that controls the operation of the wireless charging system, and shuts off the normal operation of the wireless charging system when the controller determines that there is a foreign object.
  • the alarm in the sixth possible implementation manner of the third aspect of the present application can effectively improve the user experience of the foreign object detection device.
  • a fourth aspect of the present application provides a wireless charging and transmitting system.
  • the wireless charging and transmitting system includes the wireless charging foreign body detection device and the wireless charging transmitting device provided in the third aspect.
  • the wireless charging foreign body detection device is used to detect State whether there are foreign objects in the wireless charging transmission system.
  • the wireless charging and transmitting system provided in the fourth aspect of the present application can improve the accuracy of foreign object detection of the wireless charging and transmitting system and reduce misjudgments.
  • a fifth aspect of the present application provides a wireless charging receiving system.
  • the wireless charging receiving system includes the wireless charging foreign body detection device and the wireless charging receiving device provided in the third aspect.
  • the wireless charging foreign body detection device is used for detecting State whether there are foreign objects in the wireless charging receiving system.
  • the wireless charging receiving system provided in the fifth aspect of the present application can improve the accuracy of foreign object detection of the wireless charging receiving system and reduce misjudgments.
  • a sixth aspect of the present application provides a wireless charging system.
  • the wireless charging system includes the wireless charging foreign body detection device and the wireless charging device provided in the third aspect, and the wireless charging foreign body detection device is used to detect the wireless charging Whether there are foreign objects in the system.
  • the wireless charging system provided in the sixth aspect of the present application can improve the accuracy of foreign object detection of the wireless charging system and reduce misjudgments.
  • Using the foreign body detection method, device or system described in this application can eliminate the foreign body detection process caused by the change in the induced voltage of the resonant network caused by the change in the magnetic field of the transmitter coil, such as the output power, output voltage, and output current changes of the transmitter coil. Therefore, the accuracy of foreign body detection is improved and misjudgment is reduced.
  • FIG. 1 is a schematic diagram of the relationship between impedance and frequency of a detection circuit provided by an embodiment of the application;
  • FIG. 2 is a comparison diagram of voltage characteristic curves of a detection circuit for superimposing interference induced voltage in the absence of metal foreign objects according to an embodiment of the application;
  • FIG. 3 is a schematic diagram of a wireless charging system provided by an embodiment of the application.
  • FIG. 4 is a schematic structural diagram of a wireless charging system provided by an embodiment of the application.
  • FIG. 5 is a schematic structural diagram of a foreign object detection device provided by an embodiment of the application.
  • FIG. 6 is a schematic diagram of a parallel resonant network provided by an embodiment of the application.
  • FIG. 7 is a comparison diagram of input impedance characteristic curves of a resonant network with and without metal foreign objects provided by an embodiment of the application;
  • FIG. 8 is a schematic flowchart of a foreign body detection method provided by an embodiment of the application.
  • FIG. 9 is a schematic flowchart of another foreign body detection method provided by an embodiment of the application.
  • Wireless charging also known as wireless power transfer (Wireless Power Transfer, WPT)
  • WPT Wireless Power Transfer
  • WPT wireless Power Transfer
  • the wireless charging technology of consumer electronic products for example, in the application of smart terminals, electric toothbrushes and other products It is already relatively mature.
  • the field of electric vehicles is also vigorously developing wireless charging technology.
  • the two technical solutions of magnetic induction coupling and resonance coupling are the most widely used. Both of these technical solutions are based on the principle of electromagnetic induction.
  • a high-frequency magnetic field is generated by the high-frequency alternating current of the transmitting coil, and the energy is transmitted from the transmitting coil to the receiving coil through the high-frequency magnetic field to realize wireless charging.
  • the usual wireless charging system consists of a power transmitting device connected to the mains and a power receiving device connected to the load. There is no electrical contact between the power transmitting device and the power receiving device, and wireless energy transmission is performed through electromagnetic induction.
  • Commonly used foreign body detection methods include main power coil detection, auxiliary foreign body detection coil, infrared imaging, temperature detection, acoustic wave detection, magnetoresistance detection, etc.
  • a method of using parallel resonant network to detect metal foreign objects is that the detection circuit works at resonant frequency, and a constant current source is injected into the parallel resonant network.
  • the resonance frequency is ⁇ r.
  • Due to The electromagnetic induction effect reduces the inductance of the detection circuit and increases the resonance frequency.
  • Due to the high quality factor of the parallel resonant network after the resonance frequency point, the impedance curve drops quickly, the impedance change range is small, and the detection accuracy is low.
  • the frequency is 3dB lower than ⁇ r before the resonance frequency point. Point ⁇ 3dB is the detection point.
  • the impedance characteristics of the detection circuit are characterized by the voltage across the resonant circuit.
  • the voltage Ueq1 corresponding to the equivalent impedance Zeq1 of the detection circuit at the frequency ⁇ 3dB point is measured in advance and stored in the memory.
  • FIG. 1 The schematic diagram of the relationship between the impedance and frequency of the detection circuit is shown in Figure 1, where the solid line represents the presence of metal foreign objects, the dashed line represents the absence of metal foreign objects, the horizontal axis represents frequency, and the vertical axis represents impedance.
  • FIG. 2 shows the comparison diagram of the voltage characteristic curve of whether or not the interference induced voltage is superimposed in the absence of metal foreign bodies.
  • the interference induced voltage can be the induced voltage of the transmitting coil.
  • the circuit parameters of the transmitting coil for example, the output power, output voltage, and output current of the transmitting coil will cause the induced voltage ⁇ Ug, the voltage Ueq corresponding to the equivalent impedance of the parallel resonance network
  • the curve that varies with frequency is a dotted line.
  • the induced voltage ⁇ Ug of the detection circuit When the induced voltage ⁇ Ug of the detection circuit is superimposed with the voltage Ueq corresponding to the equivalent impedance of the parallel resonant network of the detection circuit, the curve that varies with frequency is a dotted line. At a certain frequency point, for example, the frequency is When the value of ⁇ Ug when Ueq+ ⁇ Ug is detected at ⁇ 3dB exceeds the set threshold, it will be mistaken for foreign matter, which will cause misjudgment. The change of the circuit parameters of the transmitter coil will also cause the voltage of the detection circuit to change. Therefore, the cause of the voltage change of the detection circuit may be the impedance change of the detection circuit caused by the metal foreign body, or the magnetic field of the transmitter coil may cause the detection circuit to change. The induced voltage interference.
  • the existing metal foreign body detection method does not eliminate the changes caused by other factors, such as the output power of the transmitter coil, the output voltage, and the induced voltage change of the detection circuit caused by the output current change.
  • This detection scheme is easy to produce when the working conditions are complicated. Misjudgment.
  • the embodiment of the present application proposes a wireless charging foreign object detection method, device and system to solve the problems existing in the detection of foreign objects by the induced voltage method in the prior art.
  • FIG. 3 is a schematic diagram of a wireless charging system provided by an embodiment of the present application.
  • the wireless charging system includes an electric vehicle 100 and a wireless charging station 101.
  • the electric vehicle 100 may include a wireless charging receiving device 1000, and the wireless charging station 101 may include a wireless charging transmitting device 1010.
  • the charging process of the electric vehicle by the wireless charging system is performed by the wireless charging receiving device 1000 located in the electric vehicle 100 and the wireless charging transmitting device 1010 located in the wireless charging station 101 to perform non-contact charging.
  • the function of the wireless charging transmitter 1010 in the charging station 101 is to send AC power to the wireless charging receiving device 1000 in the electric vehicle 100, and the wireless charging receiving device 1000 in the electric vehicle 100 is to receive wireless charging from the wireless charging station 101.
  • the electric energy transmitted by the charging transmitter 1010 is stored in the battery of the electric vehicle to complete the charging of the electric vehicle.
  • the electric vehicle 100 includes a hybrid electric vehicle or a pure electric vehicle; the wireless charging station 101 includes a fixed wireless charging station, a fixed wireless charging parking space, a wireless charging road, and the like.
  • the wireless charging transmitter 1010 can be set on the ground or buried under the ground ( Figure 3 shows the case where the wireless charging transmitter 1010 is buried under the ground), and can wirelessly charge the electric vehicle 100 located above it.
  • the wireless charging receiving device 1000 can be specifically integrated into the bottom of the electric car 100 or other parts of the car. When the electric car 100 enters the wireless charging range of the wireless charging transmitter 1010, the electric car 100 can be charged in a wireless charging manner.
  • the wireless charging and transmitting device 1010 can also be integrated and separate.
  • the integrated method refers to the integration of the control circuit and the transmitting coil.
  • the separate method refers to the separation of the transmitting coil and the control circuit, and the power receiving antenna of the receiving device 1000 and The rectifier circuit can be integrated or separated, and the rectifier module is usually placed in the car when it is separated.
  • the non-contact charging may be wireless energy transmission by the wireless charging receiving device 1000 and the wireless charging transmitting device 1010 through an electric or magnetic field coupling method, specifically electric field induction, magnetic induction, magnetic resonance or wireless radiation.
  • an electric or magnetic field coupling method specifically electric field induction, magnetic induction, magnetic resonance or wireless radiation.
  • the electric vehicle 100 and the wireless charging station 101 can also be charged in both directions.
  • the electric vehicle 100 and the wireless charging station 101 both include the wireless charging receiving device 1000 and the wireless charging transmitting device 1010, either The wireless charging station 101 charges the electric vehicle 100 through the power supply, or the electric vehicle 100 discharges to the power supply.
  • FIG. 4 shows a schematic structural diagram of a wireless charging system.
  • the wireless charging system is composed of a transmitting device 201 and a receiving device 202.
  • Figure 4 (left) shows a schematic structural diagram of a wireless charging transmitter 201 in a wireless charging station.
  • the wireless charging and transmitting device 201 includes: a power supply 2017, a transmission conversion module 2011 connected to the power supply 2017, a power transmission antenna 2012, a transmission control module 2013 connected to both the transmission conversion module 2011 and the power transmission antenna 2012, and a transmission control module 2013 connected The transmission communication module 2014, the authentication management module 2015 connected to the transmission communication module 2014, and the storage module 2016 connected to the authentication management module.
  • the transmission conversion module 2011 can be connected to the power supply 2017 to obtain energy from the power supply and convert the AC or DC power supply of the power supply into high-frequency AC power.
  • the transmission conversion module is composed of a power factor correction unit and an inverter unit.
  • the power factor correction unit can convert 220V power frequency AC power into DC power; when the power supply is DC power input, the transmission conversion module is composed of an inverter unit.
  • the power factor correction unit can ensure that the phase of the input current of the wireless charging system is consistent with the phase of the grid voltage, reduce the harmonic content of the system, and increase the power factor value to reduce the pollution of the wireless charging system to the grid and improve the efficiency and reliability of transmission.
  • the power factor correction unit can also increase or decrease the output voltage of the power factor correction unit according to the requirements of the subsequent stage to meet the required voltage requirements.
  • the inverter unit can convert the voltage output by the power factor correction unit into a high-frequency AC voltage and act on the power transmitting antenna.
  • the high-frequency AC voltage can greatly improve the transmission efficiency and transmission distance.
  • the power supply may be a power supply inside the wireless charging transmission system, or an external power supply external to the wireless charging transmission system, which is not specifically limited in this application.
  • the power transmitting antenna 2012 in the inductive coupling energy transmission mode, uses the principle of electromagnetic induction to transmit alternating current to the receiving antenna in the form of an alternating magnetic field.
  • the resonant coupling energy transmission mode it is composed of inductors and capacitors.
  • the network converts high-frequency alternating current into resonant alternating current, and transmits the resonant alternating current to the receiving end coil in an alternating magnetic field.
  • the transmission control module 2013 is used to control the voltage, current and frequency conversion parameter adjustments of the transmission conversion module 2011 circuit according to the actual wireless charging transmission power requirements, and to control the voltage and current output adjustments of the high-frequency alternating current in the power transmission antenna 2012, according to For different working conditions, that is, different coupling coefficients of the transmitting coil and receiving coil, and different receiving end power requirements, the transmitting control module can effectively adjust the electrical parameters of the transmitting coil to cope with different working conditions.
  • the transmitting communication module 2014 is used for wireless communication between the wireless charging transmitting device and the wireless charging receiving device, and the content of the communication includes power control information, fault protection information, switch machine information, interactive authentication information, etc.
  • the wireless charging transmitter device can receive the attribute information, charging request, power control information, and interactive authentication information of the electric vehicle sent by the wireless charging receiver device; on the other hand, the wireless charging transmitter device can also send wireless charging to the wireless charging receiver device. Charging transmission control information, interactive authentication information, wireless charging history data information, etc.
  • the foregoing wireless communication methods may include, but are not limited to, Bluetooth (bluetooth), wireless broadband (WIreless-Fidelity, WiFi), Zigbee protocol (Zigbee), radio frequency identification technology (RFID), and remote (Long Range). , Lora) wireless technology, near field communication technology (Near Field Communication, NFC) any one or a combination of more.
  • the transmitting communication module can also communicate with the smart terminal of the user of the electric vehicle, and the user can realize remote authentication and user information transmission through the communication function.
  • the authentication management module 2015 is used for the interactive authentication and authority management of the wireless charging transmitter and the electric vehicle in the wireless charging system.
  • the processor in this module can process the interactive authentication and authority management information, and control the transmitting end to the authentication and authority passing The receiving end turns on the wireless charging function.
  • the storage module 2016 is used to store the charging process data, interactive authentication data (for example, interactive authentication information), and authority management data (for example, authority management information) of the wireless charging transmitter.
  • interactive authentication data and authority management data can be factory settings or It can be set by the user, which is not specifically limited in the embodiment of the present application.
  • Fig. 4 shows a schematic structural diagram of a wireless charging receiving device 202 in an electric vehicle.
  • the wireless charging receiving device 202 includes a power receiving antenna 2021, a receiving control module 2023 connected to the power receiving antenna, a receiving conversion module 2022 connected to the receiving control module, and a receiving communication module 2024.
  • the receiving conversion module can also be connected to the energy storage module 2026 through the connection with the energy storage management module 2025, and the energy storage management module 2025 can receive the energy received by the antenna 2021 for charging the energy storage module, It is further used in a vehicle drive device 2027 of an electric vehicle.
  • the energy storage management module and the energy storage module may be located inside the wireless charging receiving device or outside the wireless charging receiving device, which is not specifically limited in the embodiment of the present application.
  • the power receiving antenna 2021 in the inductively coupled energy transmission mode or the resonantly coupled energy transmission mode, is based on the principle of electromagnetic induction, and is used to receive the energy of the alternating magnetic field from the power transmitting antenna and output alternating current.
  • the receiving control module 2023 is used to control the voltage, current and frequency conversion parameters of the receiving conversion module according to the actual wireless charging receiving power requirements.
  • the receiving conversion module 2022 is used to convert the high-frequency current or voltage received by the power receiving antenna into a DC voltage or a DC current required for charging the energy storage module.
  • the receiving conversion module is usually composed of a rectification unit and a DC conversion unit; the rectification unit converts the high-frequency current and voltage or high-frequency resonance current and voltage received by the power receiving antenna into a DC voltage and a DC current, and the DC conversion unit is a subsequent charging circuit Provide stable DC voltage to achieve constant mode charging.
  • the receiving communication module 2024 is used for wireless communication between the wireless charging transmitting device and the wireless charging receiving device. Including power control information, fault protection information, switch machine information, interactive authentication information, etc.
  • the wireless charging receiving device can send the attribute information, charging request, power control information and interactive authentication information of the electric vehicle to the wireless charging transmitting device; on the other hand, the wireless charging receiving device can also receive the transmission sent by the wireless charging transmitting device.
  • the aforementioned wireless communication methods may include, but are not limited to, Bluetooth (bluetooth), wireless broadband (WIreless-Fidelity, WiFi), Zigbee protocol (Zigbee), radio frequency identification technology (RFID), and remote (Long Range).
  • the receiving communication module can also communicate with the smart terminal of the user of the electric vehicle.
  • the user uses the communication function to realize remote authentication and user information transmission, and the smart terminal controls the vehicle and the transmitter to perform wireless charging interaction.
  • the eddy current effect of the foreign body in the magnetic field formed by the transmitting coil causes the transmission efficiency of the wireless charging system to decrease.
  • the first embodiment of the present application provides a foreign object detection device.
  • the detection device includes an AC source 301, a resonance network 302, a measurement circuit 303 and a controller 304, and is used to detect whether there is a foreign object in the wireless charging system.
  • Foreign matter includes metallic foreign matter and non-metallic foreign matter.
  • the foreign object detection device can be applied in wireless charging scenarios of electric vehicles, and can also be applied in other wireless charging scenarios, such as drone wireless charging scenarios or other electronic equipment wireless charging scenarios.
  • the wireless charging foreign object detection device may be a part of the wireless charging transmission device, that is, integrated in the wireless charging transmission device or connected and communicating with the wireless charging transmission device, or the wireless charging foreign object detection device may be a part of the wireless charging receiving device, That is, it is integrated in the wireless charging receiving device or connected to and communicating with the wireless charging receiving device, or the wireless charging foreign object detection device is independent.
  • the AC source 301 may be a constant current source, capable of outputting a constant AC current whose frequency can be arbitrarily set, and providing AC excitation for the resonant network 302.
  • the constant AC refers to that the current does not change with the load.
  • the setting range of the frequency of the constant alternating current is 10KHz-10MHz.
  • the constant AC source can improve the stability of the foreign body detection device.
  • the resonance network 302 is used to detect whether there is a foreign object between the wireless charging transmitting device and the receiving device.
  • it can be a parallel resonant network circuit.
  • the resonant network 302 includes N equivalent detection coils, and N is an integer greater than or equal to 1. Any one of the N detection coils includes a switch, an inductance element and a capacitance element, the switch is connected in series with the inductance element, and the capacitance element is in parallel with the inductance element.
  • the resonant network 302 is a resonant network composed of N inductive elements (L1...Ln) and capacitive elements C1, wherein each of the N inductive elements L1, L2...Ln is connected to
  • the resonant circuit formed after the circuit can be regarded as each equivalent detection coil, that is, there are N detection coils in total, and any detection coil of the N detection coils includes a switch, an inductance element, and a capacitance element. Multiple detection coils can increase the coverage area for foreign object detection.
  • the so-called equivalent in the equivalent detection coil refers to the equivalent total inductance of multiple inductance coils connected in series or in parallel.
  • each equivalent coil refers to a coil composed of each equivalent inductance and capacitor C1.
  • switch S1, S2...Sn when foreign object detection is performed, switch S1, S2...Sn in turn, and perform foreign object detection on the area covered by the coils of the connected parallel resonant network including inductance elements L1, L2...Ln, respectively. Detection.
  • Figure 6 is a schematic diagram of a parallel resonant network.
  • the coil including the inductance element L1 and the capacitive element C1 are connected in parallel to form a parallel resonant network.
  • ⁇ is the resonant angular frequency
  • L is the inductance value of the inductance element L1
  • C is the capacitance value of the capacitive element C1.
  • the constant AC source Is ie, AC source 301
  • C1 can be considered as the equivalent resonant capacitance of the resonant network.
  • the resonant network 302 Before the hardware circuit design, the finite element simulation of the magnetic field can be carried out by changing the shape, size, connection mode and Inductance, etc., perform the magnetic field simulation of foreign body detection for various metals of different sizes and different materials, and determine the solution with better detection accuracy as the method of coil design.
  • Each equivalent coil of the resonant network can be used as a detection coil. Therefore, the resonant network 302 can be regarded as a detection coil network composed of a plurality of detection coils.
  • the resonant network uses multiple detection coils to cover a larger detectable area. It is understood that there can also be one detection coil. The specific number and area of detection coils can be designed according to actual working conditions. Do restrictions.
  • the detection coil is a parallel resonance network. According to the impedance characteristic of the parallel resonant network, the impedance characteristic curve of the input impedance Z1 of the resonant network without metal foreign matter can be drawn, and the impedance characteristic of the input impedance Z1 of the resonant network is expressed as equation (1).
  • ⁇ is the resonant angular frequency
  • L is the inductance value of the detection coil formed by the switch in the resonant network
  • C is the capacitance value of the capacitor C1
  • ⁇ is the circumference ratio.
  • the inductance change ⁇ L in the foreign body detection coil caused by electromagnetic induction is usually only about 2%.
  • the impedance characteristic of the resonant network input impedance Z2 is expressed as equation (2).
  • Fig. 7 is the impedance characteristic curve comparison chart of the resonant network input impedance Z1 and Z2 when there are metal foreign objects and no metal foreign objects.
  • the input impedance Z1 of the resonant network without metal foreign objects is larger than the input impedance Z2 of the resonant network with metal foreign objects;
  • the input impedance of the resonant network when there is a foreign object near the resonant frequency point fw of the resonant network when there is a metal foreign object and when there is no metal foreign object can be considered to be approximately the same;
  • the input impedance of the resonant network is larger than that when there is no metal foreign body.
  • the farther away from the design resonance frequency point f of the resonant network when there is no metal foreign body the smaller the impedance difference of the resonant network will be when there is a metal foreign body at the same frequency and when there is no metal foreign body. Therefore, in order to improve the detection accuracy, It is best to select detection points within a certain offset range. It can be seen from the impedance characteristic curve that when the frequency shift exceeds 10% of the resonant frequency, there is a metal foreign body and there is no metal foreign body, the difference between the input impedance of the resonant network is very small, and the detection accuracy is low. So suppose the frequency offset range ⁇ f is 10% of the resonance frequency
  • the measurement circuit 303 is used to measure the input voltage of the resonant network.
  • the measurement process includes processing processes such as voltage sampling, filtering, and amplification.
  • the output of the measurement circuit is a voltage proportional to the input voltage of the resonant network.
  • the measurement circuit can be a common voltage measurement circuit or a voltage measurement device.
  • the controller 304 is used to process the voltage signal U1 measured by the measuring circuit and the initial voltage signal U2 when there is no metal foreign matter pre-stored in the controller, and perform corresponding calculations, according to the comparison between the calculation result and the preset threshold To determine whether there is a metal foreign body, if the result is greater than the threshold, it is determined that there is a metal foreign body, and if the result is not greater than the threshold, it is determined that there is no metal foreign body.
  • the controller 304 may include a filtering unit, a calculation unit, an amplification unit, and a comparison unit.
  • the filter unit is used to filter out the excitation frequency components of the AC source 301;
  • the calculation unit is used to calculate the voltage signal,
  • the amplifying unit is used to amplify the calculated output signal to a size that is easy to distinguish, and
  • the comparison unit is used to compare the output of the previous stage and Set the threshold, and output different signals according to the comparison result, for example, a high-level signal and a low-level signal.
  • the internal structure of the controller is not limited, and all devices, modules or units that can realize voltage signal processing and compare the value relationship between U1 and U2 belong to the controller described in this application.
  • the controller 304 may also include a memory for storing the initial voltage signal U2 when there is no metal foreign matter.
  • the controller 304 may also include a control unit for determining the frequency test points f1 and f2 and sending the signal containing the frequency test points f1 and f2 to the AC source 301 to control the frequency of the AC power output by the AC source.
  • the controller 304 collects the output voltage signal U1 of the resonant network 302 and the initial voltage signal U2 when there is no metal foreign matter pre-stored in the controller, and uses U1 and U2 as signal sources. Equal in size. After a series of filtering, amplification, addition and other methods to process the signal, U1 and U2 are subtracted to zero, and the controller 304 outputs signal A, indicating that there is no foreign matter in the wireless charging system. When the voltages U1 and U2 are not equal, U1 and U2 After U2 is subtracted, it is not zero, and the controller 304 outputs a signal B, indicating that there is a foreign object in the wireless charging system.
  • Signal A and signal B can be digital signals with significant recognizable differences or analog signals with significant recognizable differences that can be recognized by other parts of the system.
  • signal A is low or zero, and signal B is high. flat.
  • it may also include a switch that controls the operation of the wireless charging system, and the normal operation of the wireless charging system is turned off by the identification signal B to prevent accidents; it may also include an alarm for alarm when the controller 304 determines that there is a foreign object. , By identifying different signals and making different physical actions, remind users to pay attention to foreign body intrusion. When there is no foreign body intrusion, signal A is recognized by the alarm, and the alarm does not respond.
  • the signal B is recognized by the alarm, and the alarm makes a physical response, such as an alarm including an LED light, the LED light flashes; an alarm including a buzzer, the buzzer emits a sound. This reminds the user that there is metal foreign body intrusion.
  • the controller 304 is used to determine the actual resonant frequency f of the resonant network; determine the frequency test points f1 and f2, where f1 is less than the actual resonant frequency f of the resonant network, and f2 is greater than the actual resonant frequency f of the resonant network;
  • both f1 and f2 can also be less than the actual resonance frequency f of the resonant network.
  • the preset voltage U 1f1 is the input voltage of the resonance network 302 at the frequency f1 when there is no metal foreign matter; the difference voltage ⁇ U2 is calculated, and the difference voltage ⁇ U2 is the preset voltage U 1f2 and the input voltage U 2f2 of the resonance network 302 at the frequency f2
  • the difference between ⁇ U2 U 1f2- U 2f2
  • the preset voltage U 1f2 is the input voltage of the resonance network at frequency
  • the controller 304 determines the actual resonant frequency f of the resonant network; determines the frequency test points f1 and f2, where f1 is smaller than the actual resonant frequency f of the resonant network, and f2 is greater than the actual resonant frequency f of the resonant network.
  • both f1 and f2 may be smaller than the actual resonant frequency f of the resonant network.
  • the frequency test points can be M, where M is an even number greater than or equal to 2.
  • the frequency of 0.5M frequency points is less than the actual resonance frequency of the resonant network, 0.5
  • the frequency of the M frequency points is greater than the actual resonant frequency of the resonant network.
  • the difference voltage or difference impedance of the resonant network 302 at each frequency point is determined, and the total difference impedance is determined.
  • the difference impedance is the maximum value of the absolute value of the difference impedance at each frequency point.
  • FIG. 8 is a schematic flow chart of the foreign body detection method.
  • the core flow of the method is as follows:
  • S401 Determine the actual resonance frequency f of the resonance network. In the absence of metal foreign objects, calculate the actual resonant frequency of the resonant network 302 according to the measured inductance of each equivalent coil, or perform a frequency sweep near the resonant frequency design value of the resonant network 302 to determine the resonant network 302 The actual resonant frequency f.
  • the resonant frequency is determined, but due to the certain accuracy range of the components of the resonant network, there will be some errors between the design value and the actual value. Therefore, in the circuit debugging process before the actual foreign body detection, it is necessary to first measure the inductance value and capacitance value of each equivalent coil, and calculate the resonance frequency of the resonance network corresponding to each equivalent coil when there is no metal foreign body.
  • the resonant frequency can also be detected by means of frequency sweeping. Frequency sweeping refers to changing the excitation frequency of the constant current AC source to change the excitation frequency of the constant current AC source within a range. At this time, measure the frequency of the resonant network.
  • the frequency of the corresponding constant current AC source is the resonant frequency of the resonant network. Because the deviation between the design value and the actual value is usually not very large, it is usually possible to sweep around the design value of the resonant frequency.
  • the frequency corresponding to the maximum voltage on the resonant network is determined as when there is no metal foreign matter.
  • the relationship between the frequency test points f1 and f2 and the resonant frequency f is: f1 is less than the actual resonant frequency f of the resonant network, and f2 is greater than the actual resonant frequency f of the resonant network.
  • both f1 and f2 may also be smaller than the actual resonance frequency f of the resonance network.
  • both f1 and f2 may also be greater than the actual resonance frequency f of the resonance network.
  • the selection standard of the value of ⁇ f depends on the impedance characteristic curve. The principle of selection is that the difference in impedance between foreign objects and no foreign objects at the same frequency is more obvious.
  • the value of ⁇ f The value range is [0.01f, 0.5f].
  • S403 Determine the input voltage U 1f1 of the resonance network at the frequency point f1 and the input voltage U 1f2 at the frequency point f2 when there is no metal foreign matter, using U 1f1 as the preset voltage at the frequency point f1 and U 1f2 as the frequency The preset voltage at point f2.
  • the constant current source sends a current excitation with frequency f1
  • the measuring circuit detects the input voltage U 1f1 of the resonance network 302, and saves the frequency f1 and the input voltage U 1f1 in the memory of the controller 304.
  • the constant current source sends a current excitation with a frequency of f2, the measuring circuit detects the input voltage U 1f2 of the resonance network 302, and saves the frequencies f2 and U 1f2 in the memory of the controller 304.
  • S404 metallic foreign matter detection is performed to determine the resonant network 302 in the input voltage U at the frequencies f1 and 2f1 input voltage at frequencies f2 U 2f2.
  • the constant current source sends a current excitation with frequency f1
  • the measuring circuit 303 detects the input voltage U 2f1 of the resonance network 302, and saves the frequency f1 and the input voltage U 2f1 in the memory of the controller 304.
  • the constant current source sends a current excitation with a frequency of f2, and the measuring circuit 303 detects the input voltage U 2f2 of the resonance network 302, and saves the frequencies f2 and U 2f2 in the memory of the controller 304.
  • S405 calculating the resonant network 302 at a predetermined voltage U at the frequencies f1 1f1 and 2f1 of the difference between the input voltage U ⁇ U1, ⁇ U1 is the difference frequency of the voltage at the point f1.
  • the controller 304 compare the input voltage U 1f1 of the resonant network when there is no metal foreign body and the current excitation frequency of the constant current source is f1 with the value of the resonant network when the metal foreign body is detected and the current excitation frequency of the constant current source is f1.
  • the difference ⁇ U1 of the input voltage U 2f1 , ⁇ U1 U 1f1- U 2f1 .
  • ⁇ U1 U 1f1 -U 2f1
  • ⁇ U1 U 1f1 -U 2f1 ⁇ U set1
  • S406 Calculate the difference ⁇ U2 between the preset voltage U 1f2 at the frequency point f2 and the input voltage U 2f2 of the resonance network 302, where ⁇ U2 is the difference voltage at the frequency point f2.
  • the controller 304 compare the input voltage U 1f2 of the resonant network when there is no metal foreign body and the current excitation frequency of the constant current source is f2 with the value of the resonant network when the metal foreign body is detected and the current excitation frequency of the constant current source is f2.
  • the difference ⁇ U2 of the input voltage U 2f2 , ⁇ U2 U 1f2- U 2f2 .
  • ⁇ U2 U 1f2 -U 2f2
  • S407 Calculate the absolute value ⁇ U of the voltage difference between the difference voltage at the frequency point f1 and the difference voltage at the frequency point f2, where ⁇ U is the total difference voltage.
  • 0. When there is a metal foreign body, the presence of the foreign body will distort the induced magnetic field. For example, the metal foreign body will also be induced in the time-varying magnetic field. Generate a magnetic field. Non-metallic foreign bodies such as biological foreign bodies can also distort the time-varying magnetic field. Therefore, the embodiments of the present application can also be used in other non-metallic foreign body detection application scenarios.
  • the eddy current magnetic field generated by the metal foreign body will generate an induced electromotive force on the resonance network 302, that is, the foreign body induced voltage is superimposed on the input voltage of the resonance network 302, as shown in FIG. 1, which can be seen from FIG. It can be seen that the impedance of the resonant circuit is different in the two cases whether there are metal foreign objects on both sides of the ⁇ 1 frequency near the resonant frequency ⁇ r.
  • the impedance of the detection circuit when there is a metal foreign object is greater than the impedance of the resonant circuit when there is no metal foreign object; when the frequency is greater than ⁇ 1, the impedance of the resonant circuit when there is a metal foreign object is less than the impedance of the detection circuit when there is no metal foreign object.
  • the difference in impedance affects the difference in voltage.
  • a threshold U set can be preset according to the requirements of the specific working conditions and the error range.
  • the controller 304 the total difference voltage ⁇ U is compared with the threshold preset by the controller.
  • the input voltage of the resonant network is U 1f1 , and the magnetic field of the transmitter coil changes at a constant current.
  • the current excitation frequency of the source is f1
  • an interference voltage Ui 1 is generated.
  • the constant current source sends a current excitation with a frequency of f1.
  • the input voltage of the resonance network 302 detected by the measuring circuit 303 should be U 2f1 + Ui 1 .
  • the transmitter magnetic field changes the constant current source for generating excitation frequency f2 when the interference voltage Ui 2, the metal
  • the constant current source sends a current excitation with a frequency of f2, and the input voltage of the resonant network 302 detected by the measuring circuit 303 should be U 2f2 +Ui 2 .
  • 0. It can be understood that in fact, the total difference voltage ⁇ U will be less than a threshold, and there will be no misjudgment.
  • the total difference voltage when there is a foreign body is the same as the total difference voltage when there is no induced voltage interference and there is a foreign body, and the threshold setting can also be the same, and there will be no misjudgment.
  • the third embodiment of the present application provides another foreign object detection method.
  • the measurement circuit detects the impedance of the resonant network.
  • the excitation of the resonant network is an AC current source
  • detecting the voltage is the most direct method.
  • After detecting the impedance of the resonant network it can also be based on the measured Calculate the voltage of the resonant network based on the impedance and current data of the current source.
  • impedance detection methods such as impedance detection circuits or impedance detection devices, which are not limited here.
  • Figure 9 shows the flow chart of the metal foreign body detection method. The core process of the method is as follows:
  • S501 Determine the actual resonance frequency f of the resonance network. In the absence of metal foreign objects, calculate the actual resonant frequency of the resonant network 302 according to the measured inductance of each equivalent coil, or perform a frequency sweep near the resonant frequency design value of the resonant network 302 to determine the resonant network 302 The actual resonant frequency f.
  • the resonant frequency is determined, but due to the certain accuracy of the components of the resonant network, there will be some errors between the design value and the actual value. Therefore, in the circuit debugging process before the actual foreign body detection, it is necessary to first measure the inductance value and capacitance value of each equivalent coil, and calculate the resonance frequency of the resonance network corresponding to each equivalent coil when there is no metal foreign body.
  • the resonant frequency can also be detected by means of frequency sweeping. Frequency sweeping refers to changing the excitation frequency of the constant current AC source to change the excitation frequency of the constant current AC source within a range. At this time, measure the frequency of the resonant network.
  • the frequency of the corresponding constant current AC source is the resonant frequency of the resonant network. Because the deviation between the design value and the actual value is usually not very large, it is usually possible to sweep around the design value of the resonant frequency.
  • the frequency corresponding to the maximum voltage on the resonant network is determined as when there is no metal foreign matter.
  • S502 Determine the frequency test point. Since the impedance characteristic curves corresponding to different resonant frequencies have different declining speeds on both sides of the resonant frequency point, a frequency test point can be determined on both sides of the resonant frequency f of the resonant network 302 respectively. In a possible implementation manner, on both sides of the actual resonant frequency f of the resonant network 302, (f- ⁇ f) and (f+ ⁇ f) are respectively taken as the boundaries, within the interval of [(f- ⁇ f), f] Select a frequency point f1, select a frequency point f2 in the interval [f, (f+ ⁇ f)], and use f1 and f2 as the frequency test points for metal foreign body detection.
  • the relationship between the frequency test points f1 and f2 and the resonant frequency f is: f1 is less than the actual resonant frequency f of the resonant network, and f2 is greater than the actual resonant frequency f of the resonant network.
  • both f1 and f2 may also be smaller than the actual resonance frequency f of the resonance network.
  • both f1 and f2 may also be greater than the actual resonance frequency f of the resonance network.
  • the selection standard of the value of ⁇ f depends on the impedance characteristic curve. The principle of selection is that the difference in impedance between foreign objects and no foreign objects at the same frequency is more obvious.
  • the value of ⁇ f The value range is [0.01f, 0.5f].
  • S503 Determine the input impedance L 1f1 at the frequency point f1 and the input impedance L 1f2 at the frequency point f2 of the resonant network when there is no metal foreign body, using L 1f1 as the preset impedance at the frequency point f1 and L 1f2 as the frequency The preset impedance at point f2.
  • the constant current source sends a current excitation with frequency f1
  • the measuring circuit detects the input impedance L 1f1 of the resonance network 302, and saves the frequency f1 and the input impedance L 1f1 in the memory of the controller 304.
  • the constant current source sends a current excitation with a frequency of f2, the measuring circuit detects the input impedance L 1f2 of the resonant network 302, and saves the frequencies f2 and L 1f2 in the memory of the controller 304.
  • S504 determining the resonant metal foreign network 302 is performed at the input frequencies f1 and L 2f1 at the impedance at the input impedance at the frequencies f2 L 2f2 detection.
  • the constant current source sends a current excitation with frequency f1
  • the measuring circuit 303 detects the input impedance L 2f1 of the resonance network 302, and saves the frequency f1 and the input impedance L 2f1 in the memory of the controller 304.
  • the constant current source When detecting metal foreign objects, the constant current source sends a current excitation with a frequency of f2, and the measuring circuit 303 detects the input impedance L 2f2 of the resonance network 302, and saves the frequencies f2 and L 2f2 in the memory of the controller 304.
  • S505 Calculate the difference ⁇ L1 between the preset impedance L 1f1 and the input impedance L 2f1 of the resonant network 302 at the frequency point f1, where ⁇ L1 is the difference impedance at the frequency point f1.
  • the controller 304 compare the input impedance L 1f1 of the resonant network when there is no metal foreign body and the current excitation frequency of the constant current source is f1 and the input impedance L 1f1 of the resonant network when the metal foreign body is detected and the current excitation frequency of the constant current source is f1.
  • the difference ⁇ L1 of the input impedance L 2f1 , ⁇ L1 L 1f1 -L 2f1 .
  • ⁇ L1 L 1f1 -L 2f1
  • S506 Calculate the difference ⁇ L2 between the preset impedance L 1f2 and the input impedance L 2f2 of the resonant network 302 at the frequency point f2, where ⁇ L2 is the difference impedance at the frequency point f2.
  • the controller 304 compare the input impedance L 1f2 of the resonant network when there is no metal foreign body and the current excitation frequency of the constant current source is f2 and the input impedance of the resonant network when the metal foreign body is detected and the current excitation frequency of the constant current source is f2.
  • the difference ⁇ L2 of the input impedance L 2f2 , ⁇ L2 L 1f2 -L 2f2 .
  • S507 Calculate the absolute value ⁇ L of the impedance difference between the difference impedance at the frequency point f1 and the difference impedance at the frequency point f2, where ⁇ L is the total difference impedance.
  • 0. When there is a metal foreign body, the presence of the foreign body will distort the induced magnetic field. For example, the metal foreign body will also be induced in a time-varying magnetic field. Induced electromotive force, the electromotive force will generate a closed loop current inside the metal foreign body, that is, eddy current, which can generate a magnetic field. Non-metallic foreign bodies such as biological foreign bodies can also distort the time-varying magnetic field.
  • the embodiments of the present application can also be used in other non-metallic foreign body detection application scenarios.
  • the eddy current magnetic field generated by the metal foreign body will generate an induced electromotive force on the resonance network 302, which in turn will affect the input impedance, that is, the foreign body induced impedance is superimposed on the input impedance of the resonance network 302.
  • the impedance of the resonant circuit is different.
  • the impedance of the detection circuit when there is a metal foreign object is greater than the impedance of the resonant circuit when there is no metal foreign object; when the frequency is greater than ⁇ 1, the impedance of the resonant circuit when there is a metal foreign object is less than the impedance of the detection circuit when there is no metal foreign object.
  • a threshold L set can be preset according to the requirements of the specific working conditions and the error range.
  • the controller 304 the total difference impedance ⁇ L is compared with the threshold preset by the controller.
  • the input impedance of the resonant network is L 1f1 , and the magnetic field of the transmitter coil changes at a constant current.
  • the current excitation frequency of the source is f1
  • an interference impedance Li 1 is generated.
  • the constant current source sends a current excitation with a frequency of f1.
  • the input impedance of the resonant network 302 detected by the measuring circuit 303 should be L 2f1 + Li 1 .
  • the input impedance of the resonant network is L 1f2 .
  • the magnetic field change of the transmitter coil produces interference impedance Li 2 when the current excitation frequency of the constant current source is f2.
  • the constant current source sends a current excitation with a frequency of f2, and the input impedance of the resonant network 302 detected by the measuring circuit 303 should be L 2f2 +Li 2 .
  • the controller 304 compare the input impedance L 1f1 of the resonant network when there is no metal foreign matter and the current excitation frequency of the constant current source is f1, and when there is interference caused by the change in the magnetic field of the transmitting coil, the current excitation of the constant current source
  • 0. It can be understood that in fact, the total difference impedance ⁇ L will be less than a threshold, and there will be no misjudgment.
  • the total difference impedance when there is a foreign object is the same as the total difference impedance when there is no inductive impedance interference and there is a foreign object, and the threshold setting can also be the same, and there will be no misjudgment.
  • the difference in the difference voltage or the difference in the difference resistance described in the above embodiments can be the actual difference in the direction of the voltage or resistance, or the processed difference, for example, the actual difference.
  • the absolute value of the value The specific situation can be designed according to actual needs, and this application is not limited.
  • the fourth embodiment of the present application provides a foreign body detection wireless charging and transmitting system.
  • the foreign body detecting wireless charging and transmitting system includes the foreign body detection device described in the first embodiment and the wireless charging and transmitting device shown in FIG. The device is used to detect whether there are foreign objects in the wireless charging and transmitting system, which will not be repeated here.
  • the fifth embodiment of the present application provides a foreign object detection wireless charging and receiving system.
  • the foreign object detection wireless charging and receiving system includes the foreign object detection device described in the first embodiment and the wireless charging receiving device shown in FIG. The device is used to detect whether there is a foreign body in the wireless charging receiving system, which will not be repeated here.
  • the sixth embodiment of the present application provides a foreign object detection wireless charging system.
  • the foreign object detection wireless charging system includes the foreign object detection device described in the first embodiment and the wireless charging transmitting device and the wireless charging receiving device shown in FIG. 4, so The foreign body detection device is used to detect whether there is a foreign body in the wireless charging system, and it will not be repeated here.
  • the computer may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • a software program it can be implemented in the form of a computer program product in whole or in part.
  • the computer program product includes at least one computer instruction.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium.
  • the computer instructions may be transmitted from a website, computer, server, or data center.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrated with at least one available medium.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)).
  • Using the foreign object detection method, device, or system described in the embodiments of the application can eliminate foreign objects caused by changes in the induced voltage of the resonance network caused by changes in the magnetic field of the transmitting coil, such as the output power, output voltage, and output current changes of the transmitting coil.
  • the impact of the detection process thereby improving the accuracy of foreign body detection and reducing misjudgments.
  • the disclosed device and method may be implemented in other ways.
  • the device embodiments described above are merely illustrative.
  • the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods, for example, multiple units or components may be divided. It can be combined or integrated into another device, or some features can be omitted or not implemented.
  • the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate parts may or may not be physically separate.
  • the parts displayed as units may be one physical unit or multiple physical units, that is, they may be located in one place, or they may be distributed to multiple different places. . Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments of the present application.
  • the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • the above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.
  • the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium.
  • the technical solutions of the embodiments of the present application are essentially or the part that contributes to the prior art, or all or part of the technical solutions can be embodied in the form of a software product, and the software product is stored in a storage medium. It includes several instructions to make a device (which may be a single-chip microcomputer, a chip, etc.) or a processor (processor) execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage media include: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program code .

Abstract

一种用于无线充电系统的异物检测方法，该方法根据谐振网络的实际谐振频率确定第一频率和第二频率（S401、S402），分别在第一频率和第二频率处确定谐振网络电压和预设电压的差值电压（S403、S404、S405、S406），再将两个不同频率处的两个差值电压的差值的绝对值与预设阈值比较（S407、S408），判断是否存在异物。还提供了一种异物检测装置。该异物检测方法或装置，可以提高异物检测的精度，减少误判。

Description

一种无线充电异物检测方法和装置 技术领域
本申请涉及无线充电技术领域，尤其涉及一种无线充电异物检测方法和装置。
背景技术
在目前的无线充电技术中，磁感应耦合式及谐振耦合式两种技术方案应用最为广泛。这两种技术方案均基于电磁感应原理，通过发射线圈的高频交变电流产生高频磁场，通过高频磁场将能量从发射线圈传送到接收线圈，实现无线充电。通常的无线充电系统由与市电相连的功率发射装置和与负载相连的功率接收装置组成。功率发射装置和功率接收装置间没有电气接触，通过电磁感应的方式进行无线能量传输。
无线充电系统的功率发射装置的发射线圈和功率接受装置的接收线圈之间存在有空气间隙，在空气间隙中间可能会有各种异物进入。存在金属异物时，由于金属在时变磁场中的涡流效应，会在金属中产生涡流，导致金属发热,有可能发生自燃(如锡箔纸温度高到一定程度会自燃)或者燃烧其他物品(金属发热导致位于其上的树叶、纸片等燃烧)，也会降低无线充电系统的能量传输效率，为了保证系统的安全工作和传输效率，必须进行金属异物检测。
当前的无线充电系统中，常用感应电压法进行异物检测。感应电压法的原理是将检测电路置于高频磁场中，通过判断检测电路的感应电压是否出现异常来判断磁场是否出现畸变，进而判断是否存在异物。现有的无线充电检测方法检测精度不够，且容易产生误判。
发明内容
本申请公开一种无线充电异物检测方法和装置，用以解决现有技术中异物检测方法和装置精度不够，容易产生误判的缺点。
本申请的第一方面，提供了一种用于无线充电系统的异物检测方法，所述方法包括：
获取谐振网络在第一频率处的第一输入电压和第二频率处的第二输入电压，其中所述第一频率小于谐振网络实际谐振频率，所述第二频率大于谐振网络实际谐振频率；
计算第一差值电压，所述第一差值电压为所述第一预设电压与第一输入电压的差值，所述第一预设电压为无金属异物时所述谐振网络在所述第一频率处的输入电压；
计算第二差值电压，所述第二差值电压为所述第二预设电压与第二输入电压的差值，所述第二预设电压为无金属异物时所述谐振网络在所述第二频率处的输入电压；
计算第三差值电压，所述第三差值电压为所述第一差值电压和所述第二差值电压的电压差的绝对值；
根据所述第三差值电压判断是否存在异物。
本申请第一方面提供的异物检测方法可以提高异物检测的精度，减少误判。
根据第一方面，在第一方面的第一种可能的实现方式中，所述根据所述第三差值电压判断是否存在异物具体包括：
判断所述第三差值电压是否大于预设阈值，若大于，则判定存在异物。
本申请第一方面的第一种可能的实现方式中确定所述谐振网络的所述实际谐振频率可以有效提高异物检测的精度。
根据第一方面或第一方面的第一种可能的实现方式，在第一方面的第二种可能的实现方 式中，在确定所述第一频率和所述第二频率前，所述方法还包括：
确定所述谐振网络的所述实际谐振频率，所述确定所述谐振网络的所述实际谐振频率具体包括：
测量所述谐振网络的电感值和电容值，根据所述电感值和所述电容值计算所述谐振网络的所述实际谐振频率；或者，
对所述谐振网络扫频，测得所述谐振网络输入电压最大时对应的频率为所述谐振网络的所述实际谐振频率。
根据第一方面或第一方面的第一至第二种可能的实现方式，在第一方面的第三种可能的实现方式中，所述第一频率在频率区间[(f-Δf)，f]选取，所述第二频率在频率区间[f，(f+Δf)]选取，所述f为所述谐振网络的所述实际谐振频率，所述Δf的取值区间为[0.01f，0.5f]。
根据第一方面或第一方面的第一至第三种可能的实现方式，在第一方面的第四种可能的实现方式中，所述谐振网络包括N个检测线圈，N为大于等于1的整数。
本申请第一方面的第四种可能的实现方式中多个检测线圈可以增加异物检测的覆盖面积。
根据第一方面或第一方面的第一至第四种可能的实现方式，在第一方面的第五种可能的实现方式中，所述N个检测线圈中任一检测线圈包括开关，电感元件和电容元件，所述开关与所述电感元件串联，所述电容元件与所述电感元件并联。
本申请的第二方面，提供了一种无线充电异物检测方法，所述方法包括：
获取谐振网络在第一频率处的第一输入阻抗和第二频率处的第二输入阻抗，其中所述第一频率小于谐振网络实际谐振频率，所述第二频率大于谐振网络实际谐振频率；
计算第一差值阻抗，所述第一差值阻抗为所述第一输入阻抗与第一预设阻抗的差值，所述第一预设阻抗为无金属异物时所述谐振网络在所述第一频率处的输入阻抗；
计算第二差值阻抗，所述第二差值阻抗为所述第二输入阻抗与第二预设阻抗的差值，所述第二预设阻抗为无金属异物时所述谐振网络在所述第二频率处的输入阻抗；
计算第三差值阻抗，所述第三差值阻抗为所述第一差值阻抗和所述第二差值阻抗的阻抗差的绝对值；
根据所述第三差值阻抗判断是否存在异物。
本申请第二方面提供的异物检测方法可以提高异物检测的精度，减少误判。
根据第二方面，在第二方面的第一种可能的实现方式中，所述根据所述第三差值阻抗判断是否存在异物具体包括：
判断所述第三差值阻抗是否大于预设阈值，若大于，则判定存在异物。
本申请第二方面的第一种可能的实现方式中确定所述谐振网络的所述实际谐振频率可以有效提高异物检测的精度。
根据第二方面或第二方面的第一种可能的实现方式，在第二方面的第二种可能的实现方式中，在确定所述第一频率和所述第二频率前，所述方法还包括：
确定所述谐振网络的所述实际谐振频率，所述确定所述谐振网络的所述实际谐振频率具体包括：
测量所述谐振网络的电感值和电容值，根据所述电感值和所述电容值计算所述谐振网络的所述实际谐振频率；或者，
对所述谐振网络扫频，测得所述谐振网络输入电压最大时对应的频率为所述谐振网络的所述实际谐振频率。
根据第二方面或第二方面的第一至第二种可能的实现方式，在第二方面的第三种可能的 实现方式中，所述第一频率在频率区间[(f-Δf)，f]选取，所述第二频率在频率区间[f，(f+Δf)]选取，所述f为所述谐振网络的所述实际谐振频率，所述Δf的取值区间为[0.01f，0.5f]。
根据第二方面或第二方面的第一至第三种可能的实现方式，在第二方面的第四种可能的实现方式中，所述谐振网络包括N个检测线圈，N为大于等于1的整数。
本申请第二方面的第四种可能的实现方式中多个检测线圈可以增加异物检测的覆盖面积。
根据第二方面或第二方面的第一至第四种可能的实现方式，在第二方面的第五种可能的实现方式中，所述N个检测线圈中任一检测线圈包括开关，电感元件和电容元件，所述开关与所述电感元件串联，所述电容元件与所述电感元件并联。
本申请的第三方面，提供了一种无线充电异物检测装置，所述装置包括交流源，谐振网络，测量电路和控制器，其中：
所述交流源用于提供交流激励；
所述谐振网络用于检测无线充电发射装置和接收装置之间是否存在异物；
所述测量电路用于测量所述谐振网络的输入电压；
所述控制器用于确定第一频率和第二频率，所述第一频率小于所述谐振网络实际谐振频率，所述第二频率大于所述谐振网络实际谐振频率；
确定所述谐振网络在所述第一频率处的第一输入电压和所述第二频率处的第二输入电压；
计算第一差值电压，所述第一差值电压为所述第一预设电压与第一输入电压的差值，所述第一预设电压为无金属异物时所述谐振网络在所述第一频率处的输入电压；
计算第二差值电压，所述第二差值电压为所述第二预设电压与第二输入电压的差值，所述第二预设电压为无金属异物时所述谐振网络在所述第二频率处的输入电压；
计算第三差值电压，所述第三差值电压为所述第一差值电压和所述第二差值电压的电压差的绝对值。
判断第三差值电压是否大于预设阈值，若大于，则判定存在异物。
本申请第三方面提供的异物检测装置可以提高异物检测的精度，减少误判。
根据第三方面，在第三方面的第一种可能的实现方式中，所述交流源包括恒定交流源。本申请第三方面的第一种可能的实现方式中的恒定交流源可以提高异物检测装置的稳定性。
根据第三方面或第三方面的第一种可能的实现方式，在第三方面的第二种可能的实现方式中，所述谐振网络包括N个检测线圈，N为大于等于1的整数。
本申请第三方面的第二种可能的实现方式中多个检测线圈可以增加异物检测的覆盖面积。
根据第三方面或第三方面的第一至第二种可能的实现方式，在第三方面的第三种可能的实现方式中，所述N个检测线圈中任一检测线圈均包括开关，电感元件和电容元件，所述开关与所述电感元件串联，所述电容元件与所述电感元件并联。
根据第三方面或第三方面的第一至第三种可能的实现方式，在第三方面的第四种可能的实现方式中，所述测量电路还用于：
测量所述谐振网络的输入阻抗。
根据第三方面或第三方面的第一至第四种可能的实现方式，在第三方面的第五种可能的实现方式中，所述控制器还用于：
确定第一频率和第二频率，所述第一频率小于谐振网络实际谐振频率，所述第二频率大于谐振网络实际谐振频率；
确定所述谐振网络在所述第一频率处的第一输入阻抗和所述第二频率处的第二输入阻抗；
计算第一差值阻抗，所述第一差值阻抗为所述第一输入阻抗与第一预设阻抗的差值，所 述第一预设阻抗为无金属异物时所述谐振网络在所述第一频率处的输入阻抗；
计算第二差值阻抗，所述第二差值阻抗为所述第二输入阻抗与第二预设阻抗的差值，所述第二预设阻抗为无金属异物时所述谐振网络在所述第二频率处的输入阻抗；
计算第三差值阻抗，所述第三差值阻抗为所述第一差值阻抗和所述第二差值阻抗的阻抗差的绝对值；
判断第三差值阻抗是否大于预设阈值，若大于，则判定存在异物。
根据第三方面或第三方面的第一至第五种可能的实现方式，在第三方面的第六种可能的实现方式中，所述异物检测装置还包括报警器，所述报警器用于：
在所述控制器判断出存在异物时报警，或者，控制无线充电系统工作的开关，在所述控制器判断出存在异物时关断无线充电系统的正常工作。
本申请第三方面的第六种可能的实现方式中的报警器可以有效提升异物检测装置的用户体验。
本申请的第四方面，提供了一种无线充电发射系统，所述无线充电发射系统包括第三方面提供的无线充电异物检测装置和无线充电发射装置，所述无线充电异物检测装置用于检测所述无线充电发射系统内是否具有异物。
本申请第四方面提供的无线充电发射系统可以提高该无线充电发射系统的异物检测的精度，减少误判。
本申请的第五方面，提供了一种无线充电接收系统，所述无线充电接收系统包括第三方面提供的无线充电异物检测装置和无线充电接收装置，所述无线充电异物检测装置用于检测所述无线充电接收系统内是否具有异物。
本申请第五方面提供的无线充电接收系统可以提高该无线充电接收系统的异物检测的精度，减少误判。
本申请的第六方面，提供了一种无线充电系统，所述无线充电系统包括第三方面提供的无线充电异物检测装置和无线充电装置，所述无线充电异物检测装置用于检测所述无线充电系统内是否具有异物。
本申请第六方面提供的无线充电系统可以提高该无线充电系统的异物检测的精度，减少误判。
使用本申请所述的异物检测方法、装置或系统，可以消除例如发射线圈的输出功率、输出电压、输出电流变化等发射线圈磁场变化引起的谐振网络的感应电压变化所带来的对异物检测过程的影响，从而提高异物检测的精度，减少误判。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例提供的一种检测电路的阻抗与频率的关系示意图；
图2为本申请实施例提供的一种无金属异物情况下是否叠加干扰感应电压的检测电路的电压特性曲线对比图；
图3为本申请实施例提供的一种无线充电系统示意图；
图4为本申请实施例提供的一种无线充电系统结构示意图；
图5为本申请实施例提供的一种异物检测装置结构示意图；
图6为本申请实施例提供的一种并联谐振网络示意图；
图7为本申请实施例提供的一种有金属异物和无金属异物时的谐振网络输入阻抗特性曲线对比图；
图8为本申请实施例提供的一种异物检测方法流程示意图；
图9为本申请实施例提供的另一种异物检测方法流程示意图。
具体实施方式
本申请应用于无线充电场景中。无线充电，又称为无线电能传输(Wireless Power Transfer，WPT)，是指通过发射装置将电能转换为其他形式的中继能量(如电磁场能、光能及微波能等)，隔空传输一段距离后，再通过接收装置将中继能量转换为电能的技术，无线充电技术在商用化上的进展十分迅猛，其中消费类电子产品的无线充电技术，例如，在智能终端、电动牙刷等产品的应用已经较为成熟，除了消费类电子产品，电动汽车领域也在大力发展无线充电技术。在无线充电技术从实验室逐渐转化为市场应用时，需要解决的关键问题之一是异物检测问题。
在目前的无线充电技术中，磁感应耦合式及谐振耦合式两种技术方案应用最为广泛。这两种技术方案均基于电磁感应原理，通过发射线圈的高频交变电流产生高频磁场，通过高频磁场将能量从发射线圈传送到接收线圈，实现无线充电。通常的无线充电系统由与市电相连的功率发射装置和与负载相连的功率接收装置组成。功率发射装置和功率接收装置间没有电气接触，通过电磁感应的方式进行无线能量传输。
无线充电系统的功率发射装置的发射线圈和功率接受装置的接收线圈之间存在有空气间隙，在空气间隙中间可能会有各种异物进入。存在金属异物时，由于金属在时变磁场中的涡流效应，会在金属内部形成感应涡流，导致金属发热,有可能发生自燃(如锡箔纸温度高到一定程度会自燃)或者燃烧其他物品(金属发热导致位于其上的树叶、纸片等燃烧)。同时，由于一部分能量被金属异物消耗掉，也会降低无线充电系统的能量传输效率。
在大功率的无线充电场景下，例如电动汽车的无线充电系统中，由于电动汽车无线充电系统的功率等级高，异物发生过热的风险大，因此为了保证系统的安全工作和传输效率，需要准确地检测金属异物，预防灾害发生。
常用的异物检测方法包括主功率线圈检测、辅助异物检测线圈、红外成像、温度检测、声波检测、磁阻检测等。
一种利用并联谐振网络检测金属异物的方法原理是检测电路工作在谐振频率下，给并联谐振网络注入恒流源，无线充电系统中无金属异物时，谐振频率为ωr，有金属异物时，由于电磁感应效应，检测电路的电感会减小，谐振频率会变大。由于并联谐振网络的品质因数高，在谐振频率点之后，阻抗曲线下降的很快，阻抗的变化幅度小，检测精度低，为了提高检测精度，在谐振频率点之前，以比ωr小3dB的频率点ω3dB为检测点，通过谐振电路两端电压来表征检测电路对应的阻抗特性，无金属异物时把检测电路在频率ω3dB点的等效阻抗Zeq1对应的电压Ueq1提前测量出并保存在存储器中，当进行金属异物检测时，测量检测电路频率在ω3dB点的等效阻抗Zeq2对应的电压Ueq2，比较两电压Ueq1和Ueq2的数值，即ΔU(3dB)＝Ueq1-Ueq2，如果ΔU(3dB)的数值超出设定的阈值认为有异物。检测电路的阻抗与频率的关系示意图如图1所示，其中实线代表有金属异物的情况，虚线代表无金属异物的情况，横轴代表频率，纵轴代表阻抗。
该方案的缺点是当无线充电系统工作时，发射线圈的磁场同样会作用于检测电路，在检 测电路上产生感应电压。如图2所示为无金属异物情况下是否叠加干扰感应电压的电压特性曲线对比图。干扰感应电压可以为发射线圈的感应电压，当发射线圈的电路参数，例如，发射线圈的输出功率、输出电压、输出电流的变化会引起感应电压ΔUg，并联谐振网络的等效阻抗对应的电压Ueq的随频率变化的曲线为虚线，检测电路的感应电压ΔUg与检测电路的并联谐振网络的等效阻抗对应的电压Ueq叠加时随频率变化的曲线为虚线，在某一频率点，例如，频率为ω3dB时检测到Ueq+ΔUg时的ΔUg的数值超出设定的阈值，会误认为有异物，从而产生误判。该发射线圈的电路参数变化同样会引起检测电路的电压变化，因此引起检测电路电压变化的原因既可能是由于金属异物而导致的检测电路电路阻抗变化，也可能是发射线圈的磁场对检测电路造成的感应电压干扰。因此，现有的金属异物检测方法没有把其他因素引起的变化，例如发射线圈的输出功率、输出电压、输出电流变化引起的检测电路的感应电压变化消除，该检测方案在工况复杂时容易产生误判。
本申请实施例基于感应电压法的原理，提出了一种无线充电异物检测方法、装置和系统，用来解决现有技术中感应电压法检测异物时所存在的问题。
为了使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请作进一步地详细描述。
电动汽车是一种新能源汽车，通过无线充电系统对电动汽车充电是一种方便、全自动、适配于自动驾驶功能的技术。图3是本申请实施例提供的一种无线充电系统示意图，该无线充电系统包含：电动汽车100和无线充电站101。电动汽车100可以包括无线充电接收装置1000，无线充电站101可以包括无线充电发射装置1010。目前，无线充电系统对电动汽车的充电过程是通过位于电动汽车100中的无线充电接收装置1000和位于无线充电站101中的无线充电发射装置1010共同工作，来进行非接触式充电的，其中无线充电站101中的无线充电发射装置1010的作用是向电动汽车100中的无线充电接收装置1000发送交流电能，电动汽车100中的无线充电接收装置1000的作用是接收来自无线充电站101中的无线充电发射装置1010传输的电能并存入电动汽车的电池中，完成对电动汽车的充电。
在一种可能的实现方式中，电动汽车100包括混合动力汽车或纯电动汽车；无线充电站101包括固定无线充电站、固定无线充电停车位、无线充电道路等。无线充电发射装置1010可以设置在地面上或者埋于地面之下(图3所示为无线充电发射装置1010埋于地面之下的情况)，可对位于其上方的电动汽车100进行无线充电。无线充电接收装置1000具体可以集成到电动汽车100的底部或汽车的其他部位，当电动汽车100进入到无线充电发射装置1010的无线充电范围内时，即可通过无线充电方式对电动汽车100充电。无线充电发射装置1010也可以是集成和分立的方式，集成的方式指的是控制电路和发射线圈集成在一起，分立的方式指的是发射线圈和控制电路分开，接收装置1000的功率接收天线和整流电路可以集成在一起，也可以是分立的，分立时整流模块通常放在车内。
可选的，非接触式充电可以是无线充电接收装置1000和无线充电发射装置1010通过电场或磁场耦合方式进行无线能量传输，具体可为电场感应、磁感应、磁共振或无线辐射方式，本申请对此不做具体限制。在一种可能的实现方式中，电动汽车100和无线充电站101还可以双向充电，当电动汽车100和无线充电站101中均包括无线充电接收装置1000和无线充电发射装置1010时，既可以由无线充电站101通过供电电源向电动汽车100充电，也可以由电动汽车100向供电电源放电。
图4示出了一种无线充电系统结构示意图，无线充电系统由发射装置201和接收装置202组成。图4(左)示出了一种无线充电站中的无线充电发射装置201的结构示意图。该无线 充电发射装置201包括：电源2017、与电源2017连接的发射变换模块2011、功率发射天线2012、与发射变换模块2011和功率发射天线2012均连接的发射控制模块2013、与发射控制模块2013连接的发射通讯模块2014、与发射通讯模块2014连接的认证管理模块2015，以及与认证管理模块连接的存储模块2016。
发射变换模块2011，可以与电源2017连接，用于从电源获取能量，并将电源的交流或直流供电转换为高频交流电。电源为交流电输入时，发射变换模块由功率因数校正单元和逆变单元组成，功率因数校正单元可以把220V工频交流电转换成直流电；电源为直流电输入时，发射变换模块由逆变单元组成。功率因数校正单元可保证无线充电系统的输入电流相位与电网电压相位一致，减小系统谐波含量，提高功率因数值，以减少无线充电系统对电网的污染，提高传输的效率和可靠性。功率因数校正单元还可根据后级需求，升高或者降低功率因数校正单元的输出电压，以满足所需的电压要求。逆变单元可以将功率因数校正单元输出的电压转换成高频交流电压，并作用在功率发射天线上，高频交流电压可极大地提高发射效率及传输距离。需要说明的是，电源可以是处于无线充电发射系统内部的电源，也可以是无线充电发射系统外接的外部电源，本申请对此不作具体限制。
功率发射天线2012，在电感耦合的能量传输模式下，利用电磁感应原理以交变磁场的方式向接收天线发射交流电，在谐振耦合的能量传输模式下，通过由电感和电容为主的器件构成的网络把高频交流电转换为谐振交流电，并将谐振交流电以交变磁场的方式传输到接收端线圈。
发射控制模块2013，用于根据实际无线充电的发射功率需求，控制发射变换模块2011电路的电压、电流和频率变换的参数调节，以及控制功率发射天线2012中高频交流电的电压和电流输出调节，根据不同的工况，即不同的发射线圈和接收线圈耦合系数、不同的接受端功率需求，发射控制模块可以有效调整发射线圈的电气参数，以应对不同工况。
发射通讯模块2014，用于无线充电发射装置和无线充电接收装置之间的无线通讯，所通讯的内容包括功率控制信息、故障保护信息、开关机信息、交互认证信息等。一方面，无线充电发射装置可以接收无线充电接收装置所发送的电动汽车的属性信息、充电请求、功率控制信息和交互认证信息；另一方面，无线充电发射装置还可向无线充电接收装置发送无线充电发射控制信息、交互认证信息、无线充电历史数据信息等。具体地，上述无线通讯的方式可以包括但不限于蓝牙(bluetooth)、无线宽带(WIreless-Fidelity，WiFi)、紫蜂协议(Zigbee)、射频识别技术(Radio Frequency Identification，RFID)、远程(Long Range，Lora)无线技术、近距离无线通信技术(Near Field Communication，NFC)中的任意一种或多种的组合。进一步地，该发射通讯模块还可与电动汽车的所属用户的智能终端进行通讯，所属用户通过通讯功能实现远程认证和用户信息传输。
认证管理模块2015，用于无线充电系统中无线充电发射装置与电动汽车的交互认证和权限管理，该模块中的处理器可以处理交互认证和权限管理信息，并控制发射端向认证和权限通过的接收端开启无线充电功能。
存储模块2016，用于存储无线充电发射装置的充电过程数据、交互认证数据(例如交互认证信息)和权限管理数据(例如权限管理信息)，其中，交互认证数据和权限管理数据可为出厂设置也可为用户自行设置的，本申请实施例对此不作具体限制。
图4(右)示出了一种电动汽车中的无线充电接收装置202的结构示意图。该无线充电接收装置202包括：功率接收天线2021、与功率接收天线连接的接收控制模块2023、与接收控制模块连接的接收变换模块2022和接收通讯模块2024。可选地，接收变换模块还可以通 过与储能管理模块2025的连接，进而与储能模块2026连接，储能管理模块2025可以功率接收天线2021所接收到的能量用于对储能模块充电，进一步用于电动汽车的车辆驱动装置2027。需要说明的是，储能管理模块和储能模块可以位于无线充电接收装置内部，也可以位于无线充电接收装置外部，本申请实施例对此不作具体限制。
功率接收天线2021，在电感耦合的能量传输模式或谐振耦合的能量传输模式下，基于电磁感应原理，用于从功率发射天线接收交变磁场的能量并输出交流电。
接收控制模块2023，用于根据实际无线充电的接收功率需求，控制接收变换模块的电压、电流和频率变换参数。
接收变换模块2022，用于把功率接收天线所接收的高频电流或电压变换成为储能模块充电所需要的直流电压或直流电流。接收变换模块通常由整流单元和直流变换单元组成；整流单元将功率接收天线所接收的高频电流和电压或高频谐振电流和电压转换成直流电压和直流电流，直流变换单元为后级充电电路提供稳定直流电压，实现恒定模式充电。
接收通讯模块2024，用于无线充电发射装置和无线充电接收装置之间的无线通讯。包括功率控制信息、故障保护信息、开关机信息、交互认证信息等。一方面，无线充电接收装置可以发送的电动汽车的属性信息、充电请求、功率控制信息和交互认证信息到无线充电发射装置；另一方面，无线充电接收装置还可以接收无线充电发射装置发送的发射控制信息、交互认证信息、无线充电历史数据信息等。具体地，上述无线通讯的方式可以包括但不仅限于蓝牙(bluetooth)、无线宽带(WIreless-Fidelity，WiFi)、紫蜂协议(Zigbee)、射频识别技术(Radio Frequency Identification，RFID)、远程(Long Range，Lora)无线技术、近距离无线通信技术(Near Field Communication，NFC)中的任意一种或多种的组合。进一步地，该接收通讯模块还可与电动汽车的所属用户的智能终端进行通讯，所属用户通过通讯功能实现远程认证和用户信息传输，通过智能终端控制汽车和发射端进行无线充电交互。
若所述无线充电系统中存在异物，由于所述异物在所述发射线圈形成的磁场中会存在涡流效应，导致无线充电系统的传输效率下降。
为了能够准确高效地检测所述无线充电系统中的异物，本申请实施例一提供了一种异物检测装置，如图5所示，为本申请实施例提供的该异物检测装置结构示意图，该异物检测装置包括交流源301，谐振网络302，测量电路303和控制器304，用于检测无线充电系统中是否存在异物。异物包括金属异物和非金属异物。该异物检测装置可以应用于电动汽车无线充电场景中，也可以应用于其他无线充电场景中，例如无人机无线充电场景或其他电子设备无线充电场景。该无线充电异物检测装置可以为无线充电发射装置的一部分，即集成在无线充电发射装置中或与无线充电发射装置连接并通信，或者，该无线充电异物检测装置可以为无线充电接收装置的一部分，即集成在无线充电接收装置中或与无线充电接收装置连接并通信，或者，该无线充电异物检测装置是独立的。
交流源301可以为恒流源，能够输出频率可任意设定的恒定交流电流，为谐振网络302提供交流激励，恒定交流电指的是该电流不随负载变化。在一种可能的实现方式中，恒等交流电的频率的设定范围为10KHz-10MHz。恒定交流源可以提升异物检测装置的稳定性。
谐振网络302用于检测无线充电发射装置和接收装置之间是否存在异物。例如，可以为并联谐振网络电路。谐振网络302包括N个等效的检测线圈，N为大于等于1的整数。N个检测线圈中任一检测线圈均包括开关，电感元件和电容元件，开关与电感元件串联，电容元件与电感元件并联。
在一种可能的实现方式中，谐振网络302为由N个电感元件(L1…Ln)和电容元件C1构 成的谐振网络，其中N个电感元件L1、L2…Ln中的每个电感元件接入电路后所形成的谐振电路均可以看做是每个等效的检测线圈，即共有N个检测线圈，N个检测线圈中的任一检测线圈均包括开关、电感元件和电容元件。多个检测线圈可增加异物检测的覆盖面积。等效的检测线圈中的所谓等效是指可能是多个电感线圈串联或者并联后等效的总的电感，等效的检测线圈中的电感元件L1、L2…Ln与电容元件C1并联，形成并联谐振网络，电感元件L1、L2…Ln与切换开关S1、S2…Sn串联。其中，每个等效线圈指的是每个等效电感与电容C1组成的线圈。在一种可能的实现方式中，进行异物检测时，轮流切换闭和开关S1、S2…Sn，分别对所接入并联谐振网络的包括电感元件L1、L2…Ln的线圈所覆盖的区域进行异物检测。例如，如图6所示为一种并联谐振网络示意图，当开关S1闭合时，包括电感元件L1的线圈与电容元件C1并联形成并联谐振网络，当发生谐振时满足式
Figure PCTCN2021070779-appb-000001
ω为谐振角频率，谐振角频率ω与谐振频率f的关系是ω＝2πf，L为电感元件L1的感值，C为电容元件C1的容值。此时由恒定交流源Is(即交流源301)提供电流激励，可以在L1与C1所围成的区域内进行金属异物检测。其中，C1可以认为是谐振网络的等效谐振电容。
可以理解的是，金属异物检测线圈(谐振网络302)的结构设计有多种方式，在进行硬件电路设计前，可以进行磁场的有限元仿真，通过改变不同小线圈的形状、尺寸、连接方式和感量等，对不同尺寸、不同材料的多种金属进行异物检测的磁场仿真，确定检测精度较优的方案作为线圈设计的方法。谐振网络的每一个等效线圈都可以作为一个检测线圈。因此，谐振网络302可以被看成是由多个检测线圈所组成的检测线圈网络。谐振网络采用多个检测线圈是为了覆盖更大的可检测面积，可以理解的是，检测线圈也可以为一个，具体的检测线圈数量和面积可以根据实际的工况进行设计，本申请在此不做限制。
在一种可能的实现方式中，经仿真与分析后，确定谐振网络302的实际谐振频率为f＝300kHz，接入电路的检测线圈的等效电感感量是100uH，等效电容容量是2.82nF，检测线圈为并联谐振网络。根据并联谐振网络的阻抗特性可以画出无金属异物时的谐振网络输入阻抗Z1的阻抗特性曲线，谐振网络输入阻抗Z1的阻抗特性表达式为式(1)。
Figure PCTCN2021070779-appb-000002
ω为谐振角频率，谐振角频率ω与谐振频率f的关系是ω＝2πf，L为谐振网络中开关所闭和形成的检测线圈的电感值，C为电容C1的电容值，π为圆周率。
根据并联谐振网络的特性可知，在谐振频率f＝300kHz处并联谐振网络的阻抗是最大值。
当有金属异物时，通常由于电磁感应在异物检测线圈中引起的感量变化ΔL通常只有2％左右，有金属异物时的谐振网络输入阻抗Z2的阻抗特性表达式为式(2)。
Figure PCTCN2021070779-appb-000003
有金属异物时异物引起的感量变化量越小越难检测，因此若要保证能检测到足够小的金属时，可以用电感量变化ΔL为1％来进行检测方法的研究，即电感变为99％L,如图7所示为有金属异物和无金属异物时的谐振网络输入阻抗Z1和Z2的阻抗特性曲线对比图。
由图7可以看出在小于无金属异物时谐振网络的谐振频率f＝300kHz的区间内，无金属异物时的谐振网络输入阻抗Z1比有金属异物时的谐振网络输入阻抗Z2大；在有金属异物时的谐振网络的谐振频率点fw附近，有金属异物时和无金属异物时的谐振网络输入阻抗可以认为是近似相同的；在大于频率点fw的区间内有金属异物时的谐振网络输入阻抗比无金属异物时的谐振网络输入阻抗大。而且离无金属异物时谐振网络的设计谐振频率点f越远，在同一个频率下有金属异物的情况和无金属异物的情况下，谐振网络的阻抗差值越小，因此为了提高 检测精度，最好是在一定的偏移范围内选择检测点。从阻抗特性曲线可以看出，当频率偏移超出谐振频率10％后有金属异物的情况和无金属异物的情况下，谐振网络的输入阻抗的区别很小，检测精度低。所以假设频率偏移范围Δf为谐振频率的10％
测量电路303用于对谐振网络的输入电压进行测量，测量过程包括电压的采样、滤波、放大等处理过程，测量电路输出的是与谐振网络输入电压成比例的电压。测量电路可以为常见的电压测量电路或电压测量装置。
控制器304用于对测量电路测量到的电压信号U1和预存在控制器中的无金属异物时的初始电压信号U2进行处理，并进行相应的计算，根据计算结果与所预设的阈值的比较来判断是否有金属异物，若结果大于阈值，则判定存在金属异物，若结果不大于阈值，则判定不存在金属异物。
控制器304内可以包括滤波单元、计算单元、放大单元和比较单元。滤波单元用于筛选出交流源301的激励频率分量；计算单元用于将电压信号进行计算，放大单元用于将计算后输出的信号放大到易于分辨的大小，比较单元用于比较前级输出和设定阈值，根据比较结果输出不同的信号，例如，高电平信号和低电平信号。可以理解的是，所述控制器内部的结构不受限制，所有能够实现电压信号处理并比较出U1与U2数值关系的器件、模块或单元，都属于本申请所述的控制器。控制器304还可以包括存储器，用于存储无金属异物时的初始电压信号U2。控制器304还可以包括控制单元，控制单元用于确定频率测试点f1和f2并将包含有频率测试点f1和f2的信号发送给交流源301，以控制交流源输出的交流电的频率。
在一种可能的实现方式中，控制器304采集谐振网络302的输出电压信号U1和预存在控制器中的无金属异物时的初始电压信号U2，将U1和U2作为信号源，U1和U2的大小相等。经过一系列滤波、放大、加法等方式处理信号，U1与U2相减后为零，控制器304输出信号A，表明无线充电系统中不存在异物，在电压U1和U2大小不相等时，U1与U2相减后不为零，控制器304输出信号B，表明无线充电系统中存在异物。信号A与信号B可以为具有显著可识别差异的数字信号或可被系统其他部分识别的具有显著可识别差异的模拟信号，例如，信号A为低电平或零电平，信号B为高电平。可选地，还可以包括控制无线充电系统工作的开关，通过识别信号B来关断无线充电系统的正常工作以防止意外发生；还可以包括报警器，用于控制器304判断出存在异物时报警，通过识别不同信号而做出不同的物理动作，提醒使用者注意异物入侵。在没有异物入侵时，信号A被报警器识别，报警器不予反应。在有异物入侵时，信号B被报警器识别，报警器做出物理反应，例如包括LED灯的报警器，LED灯闪亮；包括蜂鸣器的报警器，蜂鸣器发出声音。以此提示使用者有金属异物入侵。
在另一种可能的实现方式中，控制器304用于确定谐振网络实际谐振频率f；确定频率测试点f1和f2，f1小于谐振网络实际谐振频率f，f2大于谐振网络实际谐振频率f；可选的，f1和f2也可以均小于谐振网络实际谐振频率f，可选的，f1和f2也可以均大于谐振网络实际谐振频率f；确定谐振网络302在频率f1处的输入电压U 2f1和频率f2处的输入电压U 2f2；计算差值电压ΔU1，差值电压ΔU1为预设电压U 1f1与谐振网络302在频率f1处的输入电压U 2f1的差值，即ΔU1＝U 1f1-U 2f1，预设电压U 1f1为无金属异物时谐振网络302在频率f1处的输入电压；计算差值电压ΔU2，差值电压ΔU2为预设电压U 1f2与谐振网络302在频率f2处的输入电压U 2f2的差值，即ΔU2＝U 1f2-U 2f2，预设电压U 1f2为无金属异物时谐振网络在频率处f2处的输入电压；计算总的差值电压ΔU，总的差值电压ΔU为差值电压ΔU1和差值电压ΔU2的电压差的绝对值，即ΔU＝|ΔU1-ΔU2|；判断ΔU是否大于预设阈值，若大于，则判定存在异物，若不大于，则判定不存在异物。
在又一种可能的实现方式中，控制器304确定谐振网络实际谐振频率f；确定频率测试点f1和f2，f1小于所述谐振网络实际谐振频率f，f2大于所述谐振网络实际谐振频率f，可选的，f1和f2也可以均小于谐振网络实际谐振频率f，可选的，f1和f2也可以均大于谐振网络实际谐振频率f；确定谐振网络302在频率f1处的输入阻抗L 2f1和频率f2处的输入阻抗L 2f2；计算差值阻抗ΔL1，差值阻抗ΔL1为预设阻抗L 1f1与谐振网络302在频率f1处的输入阻抗L 2f1的差值，即ΔL1＝L 1f1-L 2f1，预设阻抗L 1f1为无金属异物时谐振网络302在频率f1处的输入阻抗；计算差值阻抗ΔL2，差值阻抗ΔL2为预设阻抗L 1f2与谐振网络302在频率f2处的输入阻抗L 2f2的差值，即ΔL2＝L 1f2-L 2f2，预设阻抗L 1f2为无金属异物时谐振网络在频率处f2处的输入阻抗；计算总的差值阻抗ΔL，总的差值阻抗ΔL为差值阻抗ΔL1和差值阻抗ΔL2的阻抗差的绝对值，即ΔL＝|ΔL1-ΔL2|；判断ΔL是否大于预设阈值，若大于，则判定存在异物，若不大于，则判定不存在异物。
可以理解的是，可选的，频率测试点可以为M个，M为大于等于2的偶数，在一种可能的实现方式中，0.5M个频率点的频率小于谐振网络的实际谐振频率，0.5M个频率点的频率大于谐振网络的实际谐振频率，按照上述实施例中的方法分别确定谐振网络302在每个频率点处的差值电压或差值阻抗，确定总的差值阻抗，总的差值阻抗为各频率点差值阻抗的绝对值的最大值。
本申请实施例二，提供一种异物检测方法，如图8所示为该异物检测方法流程示意图，该方法核心流程如下：
S401：确定谐振网络实际谐振频率f。在无金属异物的情况下，根据测量得到的每个等效线圈的电感值，计算谐振网络302的实际谐振频率，或者，在谐振网络302的谐振频率设计值附近进行扫频，确定谐振网络302的实际谐振频率f。
在谐振网络302的理论设计时，谐振频率是确定的，但由于谐振网络的器件存在一定的精度范围，会导致设计值和实际值间存在一些误差。因此在准备进行实际的异物检测前的电路调试过程中，需要首先测量每个等效线圈的电感值和电容值，计算无金属异物时每个等效线圈所对应的谐振网络的谐振频率。也可以通过扫频的方式进行谐振频率检测，扫频指的是通过改变恒流交流源的激励的频率，让恒流交流源的激励的频率在一个范围内变化，此时测量谐振网络上的输入电压，当谐振网络上的输入电压最大时对应的恒流交流源的频率就是谐振网络的谐振频率。因为设计值和实际值的偏差通常不是很大，所以通常可以在谐振频率的设计值附近进行扫频。例如，谐振频率的设计值为f d＝300kHz，在谐振频率的设计值的附近区域如[280kHz，320kHz]频率区间进行扫频，谐振网络上电压最大时对应的频率即确定为无金属异物时的初始状态下的谐振频率。因为每个的等效线圈的检测方法都一样，所以上述的流程中以一个线圈来举例，可以理解的是，其余线圈也可按照类似的方法确定实际谐振频率。
S402：确定频率测试点。由于不同的谐振频率所对应的阻抗特性曲线在谐振频率点两侧的曲线下降速度不同，因此可以在谐振网络302的谐振频率f的两侧分别确定一个频率测试点。在一种可能的实现方式中，在谐振网络302的实际谐振频率f的两侧，分别以(f-Δf)和(f+Δf)为边界，在[(f-Δf)，f]区间内选择一个频率点f1，在[f，(f+Δf)]区间内选择一个频率点f2，以f1和f2作为金属异物检测的频率测试点。频率测试点f1、f2与谐振频率f的关系是：f1小于谐振网络实际谐振频率f，f2大于谐振网络实际谐振频率f。可选的，f1和f2也可以均小于谐振网络实际谐振频率f，可选的，f1和f2也可以均大于谐振网络实际谐振频率f。其中，Δf的值的选取标准依阻抗特性曲线而定，选取的原则是在同一个频率下有异物和没有异物时的阻抗的差值比较明显，在一种可能的实现方式中，Δf的取值范围为[0.01f， 0.5f]。例如，有异物和无异物时的阻抗差值通常在谐振网络302的实际谐振频率f的左右0.1f的范围内差值较大，超出这个范围差值变小了，此时取Δf＝0.1f，即在谐振网络302的实际谐振频率f的两侧，分别以(f-0.1f)和(f+0.1f)为边界，在[(f-0.1f)，f]区间内选择一个频率点f1，在[f，(f+0.1f)]区间内选择一个频率点f2，以f1和f2作为金属异物检测的频率测试点。例如，当扫频得到谐振频率的实际值f＝300kHz时，此时计算Δf＝0.1f＝30kHz，在谐振网络302的实际谐振频率f＝300kHz的两侧，分别以f-Δf＝f-0.1f＝270kHz和f+Δf＝f+0.1f＝330kHz为边界，在[270kHz，300kHz]区间内选择一个频率点f1＝290kHz，在[300kHz，330kHz]区间内选择一个频率点f2＝314kHz，以290kHz和314kHz作为金属异物检测的频率测试点。
S403：确定无金属异物情况时谐振网络在频率点f1处的输入电压U 1f1和在频率点f2处的输入电压U 1f2，将U 1f1作为频率点f1处的预设电压，将U 1f2作为频率点f2处的预设电压。在无金属异物情况下，恒流源发送频率为f1的电流激励，测量电路检测谐振网络302的输入电压U 1f1，并把频率f1和输入电压U 1f1保存到控制器304的存储器中。在无金属异物情况下，恒流源发送频率为f2的电流激励，测量电路检测谐振网络302的输入电压U 1f2，并把频率f2和U 1f2保存到控制器304的存储器中。例如，在无金属异物情况下，恒流源发送频率为f1＝290kHz的电流激励，测量电路检测谐振网络302的输入电压U 1f1，并把频率f1＝290kHz和输入电压U 1f1保存到控制器304的存储器中。在无金属异物情况下，恒流源发送频率为f2＝314kHz的电流激励，测量电路检测谐振网络302的输入电压U 1f2，并把频率f2＝314kHz和U 1f2保存到控制器304的存储器中。
S404：确定在进行金属异物检测时谐振网络302在频率点f1处的输入电压U 2f1和在频率点f2处的输入电压U 2f2。在金属异物检测时，恒流源发送频率为f1的电流激励，测量电路303检测谐振网络302的输入电压U 2f1，并把频率f1和输入电压U 2f1保存到控制器304的存储器中。在金属异物检测时，恒流源发送频率为f2的电流激励，测量电路303检测谐振网络302的输入电压U 2f2，并把频率f2和U 2f2保存到控制器304的存储器中。例如，在金属异物检测时，恒流源发送频率为f1＝290kHz的电流激励，测量电路303检测谐振网络302的输入电压U 2f1，并把频率f1＝290kHz和输入电压U 2f1保存到控制器304的存储器中。在金属异物检测时，恒流源发送频率为f2＝314kHz的电流激励，测量电路303检测谐振网络302的输入电压U 2f2，并把频率f2＝314kHz和U 2f2保存到控制器304的存储器中。
S405：计算谐振网络302在频率点f1处的预设电压U 1f1和输入电压U 2f1的差值ΔU1，ΔU1为频率点f1处的差值电压。在控制器304中，比较无金属异物时且恒流源的电流激励频率为f1时的谐振网络的输入电压U 1f1和金属异物检测时且恒流源的电流激励频率为f1时的谐振网络的输入电压U 2f1的差ΔU1，ΔU1＝U 1f1-U 2f1。当金属异物检测时不存在金属异物，可以理解的是，理论上U 1f1＝U 2f1，ΔU1＝U 1f1-U 2f1＝0。但由于系统参数不可能完全相同，因此实际中当判断U 1f1和U 2f1的差值小于一定阈值时，即ΔU1＝U 1f1-U 2f1＜U set1，可认为金属异物检测时不存在异物。例如，f1＝290kHz时，进行金属异物检测时，ΔU1＝U 1f1-U 2f1，当金属异物检测时不存在金属异物，U 1f1与U 2f1的差值小于一定阈值，ΔU1＝U 1f1-U 2f1＜U set1；当金属异物检测时存在金属异物，U 1f1与U 2f1的差值大于一定阈值，ΔU1＝U 1f1-U 2f1＞U set1。可选的，ΔU1还可以为计算谐振网络302在频率点f1处的输入电压U 2f1和预设电压U 1f1的差值，即ΔU1＝U 2f1-U 1f1。
S406：计算谐振网络302在频率点f2处的预设电压U 1f2和输入电压U 2f2的差值ΔU2，ΔU2为频率点f2处的差值电压。在控制器304中，比较无金属异物时且恒流源的电流激励频率为f2时的谐振网络的输入电压U 1f2和金属异物检测时且恒流源的电流激励频率为f2时的谐振网 络的输入电压U 2f2的差ΔU2，ΔU2＝U 1f2-U 2f2。当金属异物检测时不存在金属异物，可以理解的是，理论上U 1f2＝U 2f2，ΔU2＝U 1f2-U 2f2＝0。但由于系统参数不可能完全相同，因此实际中当判断U 1f2和U 2f2的差值小于一定阈值时，即ΔU2＝U 1f2-U 2f2＜U set2，可认为金属异物检测时不存在异物。例如，f1＝290kHz时，进行金属异物检测时，ΔU2＝U 1f2-U 2f2，当金属异物检测时不存在金属异物，U 1f2与U 2f2的差值小于一定阈值，ΔU2＝U 1f2-U 2f2＜U set2；当金属异物检测时存在金属异物，U 1f2与U 2f2的差值大于一定阈值，ΔU2＝U 1f2-U 2f2＞U set2。可选的，ΔU2还可以为计算谐振网络302在频率点f2处的输入电压U 2f2和预设电压U 1f2的差值，即ΔU2＝U 2f2-U 1f2。
S407：计算频率点f1处的差值电压和频率点f2处的差值电压的电压差的绝对值ΔU，ΔU为总的差值电压。在控制器304中，计算频率点f1处的差值电压和频率点f2处的差值电压的电压差的绝对值得到总的差值电压，即ΔU＝|ΔU1-ΔU2|。
S408：将ΔU与预先设定的阈值相比较，根据比较结果判断是否存在金属异物。理论上，当不存在金属异物时，ΔU＝|ΔU1-ΔU2|＝0。当存在金属异物时，异物的存在会使感应磁场发生畸变，例如，金属异物在时变磁场中也会被感应出感应电动势，该电动势会在金属异物内部产生闭合回路电流，即涡流，涡流可产生磁场。生物体异物等非金属类异物同样可以使得时变磁场产生畸变，因此本申请实施例也可用于其他非金属类异物的检测应用场景。在一种可能的实现方式中，金属异物产生的涡流磁场会在谐振网络302上产生感应电动势，即在谐振网络302的输入电压上叠加异物感应电压，如图1所示，从图1可以看出，在谐振频率ωr附近的ω1频率处的两侧，是否存在金属异物两种情况下，谐振电路的阻抗大小是不同的。在频率小于ω1时，有金属异物时检测电路的阻抗大于无金属异物时谐振电路的阻抗；在频率大于ω1时，有金属异物时谐振电路的阻抗小于无金属异物时检测电路的阻抗。阻抗的不同影响着电压的不同。但异物感应电压在不同频率处与谐振网络302的输入电压之间的差值的方向与大小均不相同，即ΔU1与ΔU2不相等，ΔU＝|ΔU1-ΔU2|≠0。可以理解的是，实际应用中由于误差的存在，当不存在金属异物时，ΔU也可以不为0。因此为了增加检测精度，可以根据具体工况和误差范围的需要预先设定一个阈值U set。在控制器304中，将总的差值电压ΔU与控制器预先设定的阈值进行比较，当ΔU大于预先设定的阈值范围时，即ΔU＝|ΔU1-ΔU2|＞U set，认为存在异物；当ΔU小于预先设定的阈值范围时，即ΔU＝|ΔU1-ΔU2|＜U set，则认为无金属异物。可以理解的是，本申请实施例中在两个频率处测量电压差相比在一个频率处测量电压差的方法，可以有效提高检测精度，避免误测。
从图1中可以看出，在无金属异物情况和有金属异物两种不同的情况下，由于谐振网络的阻抗特性曲线在谐振频率两侧的差值不同，但公共干扰信号所产生的感应电压在不同频率处可以认为是近似相等的，因此按照上述方法可以有效消除不同复杂工况下出现的公共干扰信号，如发射线圈磁场变化、由于发射线圈和接收线圈间的相对位置不同导致的耦合系数不同等的干扰，提高金属异物检测准确度，减少误判，实现高精度金属异物检测的目的。
例如，当进行金属异物检测时存在发射线圈的磁场变化导致的干扰，无金属异物时且恒流源的电流激励频率为f1时的谐振网络的输入电压为U 1f1，发射线圈磁场变化在恒流源的电流激励频率为f1时产生了干扰电压Ui 1，则在金属异物检测时，恒流源发送频率为f1的电流激励，测量电路303检测到的谐振网络302的输入电压应该为U 2f1+Ui 1。无金属异物时且恒流源的电流激励频率为f2时的谐振网络的输入电压为U 1f2，发射线圈磁场变化在恒流源的电流激励频率为f2时产生了干扰电压Ui 2，则在金属异物检测时，恒流源发送频率为f2的电流激励，测量电路303检测到的谐振网络302的输入电压应该为U 2f2+Ui 2。在控制器304中， 比较无金属异物时且恒流源的电流激励频率为f1时的谐振网络的输入电压U 1f1，和存在发射线圈的磁场变化导致的干扰时，在恒流源的电流激励频率为f1处进行金属异物检测时的谐振网络的输入电压U 2f1+Ui 1的差ΔU1，ΔU1＝U 1f1-(U 2f1+Ui 1)。比较无金属异物时且恒流源的电流激励频率为f2时的谐振网络的输入电压U 1f2，和存在发射线圈的磁场变化导致的干扰时，在恒流源的电流激励频率为f2处进行金属异物检测时的谐振网络的输入电压U 2f2+Ui 2的差ΔU2，ΔU2＝U 1f2-(U 2f2+Ui 2)。在控制器304中，计算f1和f2频率点的总的差值电压ΔU＝|ΔU1-ΔU2|。而由于发射线圈的磁场变化导致的感应电压在不同频率处是相等的，即Ui 1＝Ui 2，如图2所示为谐振网络输入电压叠加干扰感应电压时随频率变化示意图，图中的Ueq为谐振网络输入电压，Ueq+ΔU为谐振网络输入电压叠加干扰感应电压。因此当不存在金属异物时，理论上，总的差值电压ΔU＝|ΔU1-ΔU2|＝0，可以理解的是，实际上总的差值电压ΔU会小于一个阈值，不会存在误判。当存在异物时的总的差值电压与没有感应电压干扰且存在异物时的总的差值电压相同，其阈值设置也可相同，同样不会产生误判。
本申请实施例三，提供另一种异物检测方法，与实施例二的区别在于，实施例三中，测量电路检测的是谐振网络的阻抗。在谐振网络的激励是交流电流源的情况下，谐振网络的电压与阻抗的关系是U＝I*Z,检测电压是最直接的方法，而检测谐振网络的阻抗后，也可以根据所测量到的阻抗与电流源的电流数据，推算出谐振网络的电压。阻抗的检测方法有很多种，例如阻抗检测电路或阻抗检测装置，此处不做限制。如图9所示为该金属异物检测方法流程图，该方法核心流程如下：
S501：确定谐振网络实际谐振频率f。在无金属异物的情况下，根据测量得到的每个等效线圈的电感值，计算谐振网络302的实际谐振频率，或者，在谐振网络302的谐振频率设计值附近进行扫频，确定谐振网络302的实际谐振频率f。
在谐振网络302的理论设计时，谐振频率是确定的，但由于谐振网络的器件存在一定的精度，会导致设计值和实际值间存在一些误差。因此在准备进行实际的异物检测前的电路调试过程中，需要首先测量每个等效线圈的电感值和电容值，计算无金属异物时每个等效线圈所对应的谐振网络的谐振频率。也可以通过扫频的方式进行谐振频率检测，扫频指的是通过改变恒流交流源的激励的频率，让恒流交流源的激励的频率在一个范围内变化，此时测量谐振网络上的输入电压，当谐振网络上的输入电压最大时对应的恒流交流源的频率就是谐振网络的谐振频率。因为设计值和实际值的偏差通常不是很大，所以通常可以在谐振频率的设计值附近进行扫频。例如，谐振频率的设计值为f d＝300kHz，在谐振频率的设计值的附近区域如[280kHz，320kHz]频率区间进行扫频，谐振网络上电压最大时对应的频率即确定为无金属异物时的初始状态下的谐振频率。因为每个的等效线圈的检测方法都一样，所以上述的流程中以一个线圈来举例，可以理解的是，其余线圈也可按照类似的方法确定实际谐振频率。
S502：确定频率测试点。由于不同的谐振频率所对应的阻抗特性曲线在谐振频率点两侧的曲线下降速度不同，因此可以在谐振网络302的谐振频率f的两侧分别确定一个频率测试点。在一种可能的实现方式中，在谐振网络302的实际谐振频率f的两侧，分别以(f-Δf)和(f+Δf)为边界，在[(f-Δf)，f]区间内选择一个频率点f1，在[f，(f+Δf)]区间内选择一个频率点f2，以f1和f2作为金属异物检测的频率测试点。频率测试点f1、f2与谐振频率f的关系是：f1小于谐振网络实际谐振频率f，f2大于谐振网络实际谐振频率f。可选的，f1和f2也可以均小于谐振网络实际谐振频率f，可选的，f1和f2也可以均大于谐振网络实际谐振频率f。其中，Δf的值的选取标准依阻抗特性曲线而定，选取的原则是在同一个频率下有异 物和没有异物时的阻抗的差值比较明显，在一种可能的实现方式中，Δf的取值范围为[0.01f，0.5f]。例如，有异物和无异物时的阻抗差值通常在谐振网络302的实际谐振频率f的左右0.1f的范围内差值较大，超出这个范围差值变小了，此时取Δf＝0.1f，即在谐振网络302的实际谐振频率f的两侧，分别以(f-0.1f)和(f+0.1f)为边界，在[(f-0.1f)，f]区间内选择一个频率点f1，在[f，(f+0.1f)]区间内选择一个频率点f2，以f1和f2作为金属异物检测的频率测试点。例如，当扫频得到谐振频率的实际值f＝300kHz时，此时计算Δf＝0.1f＝30kHz，在谐振网络302的实际谐振频率f＝300kHz的两侧，分别以f-Δf＝f-0.1f＝270kHz和f+Δf＝f+0.1f＝330kHz为边界，在[270kHz，300kHz]区间内选择一个频率点f1＝285kHz，在[300kHz，330kHz]区间内选择一个频率点f2＝320kHz，以285kHz和320kHz作为金属异物检测的频率测试点。
S503：确定无金属异物情况时谐振网络在频率点f1处的输入阻抗L 1f1和在频率点f2处的输入阻抗L 1f2，将L 1f1作为频率点f1处的预设阻抗，将L 1f2作为频率点f2处的预设阻抗。在无金属异物情况下，恒流源发送频率为f1的电流激励，测量电路检测谐振网络302的输入阻抗L 1f1，并把频率f1和输入阻抗L 1f1保存到控制器304的存储器中。在无金属异物情况下，恒流源发送频率为f2的电流激励，测量电路检测谐振网络302的输入阻抗L 1f2，并把频率f2和L 1f2保存到控制器304的存储器中。例如，在无金属异物情况下，恒流源发送频率为f1＝285kHz的电流激励，测量电路检测谐振网络302的输入阻抗L 1f1，并把频率f1＝285kHz和输入阻抗L 1f1保存到控制器304的存储器中。在无金属异物情况下，恒流源发送频率为f2＝320kHz的电流激励，测量电路检测谐振网络302的输入阻抗L 1f2，并把频率f2＝320kHz和L 1f2保存到控制器304的存储器中。
S504：确定在进行金属异物检测时谐振网络302在频率点f1处的输入阻抗L 2f1和在频率点f2处的输入阻抗L 2f2。在金属异物检测时，恒流源发送频率为f1的电流激励，测量电路303检测谐振网络302的输入阻抗L 2f1，并把频率f1和输入阻抗L 2f1保存到控制器304的存储器中。在金属异物检测时，恒流源发送频率为f2的电流激励，测量电路303检测谐振网络302的输入阻抗L 2f2，并把频率f2和L 2f2保存到控制器304的存储器中。例如，在金属异物检测时，恒流源发送频率为f1＝285kHz的电流激励，测量电路303检测谐振网络302的输入阻抗L 2f1，并把频率f1＝285kHz和输入阻抗L 2f1保存到控制器304的存储器中。在金属异物检测时，恒流源发送频率为f2＝320kHz的电流激励，测量电路303检测谐振网络302的输入阻抗L 2f2，并把频率f2＝320kHz和L 2f2保存到控制器304的存储器中。
S505：计算谐振网络302在频率点f1处的预设阻抗L 1f1和输入阻抗L 2f1的差值ΔL1，ΔL1为频率点f1处的差值阻抗。在控制器304中，比较无金属异物时且恒流源的电流激励频率为f1时的谐振网络的输入阻抗L 1f1和金属异物检测时且恒流源的电流激励频率为f1时的谐振网络的输入阻抗L 2f1的差ΔL1，ΔL1＝L 1f1-L 2f1。当金属异物检测时不存在金属异物，可以理解的是，理论上L 1f1＝L 2f1，ΔL1＝L 1f1-L 2f1＝0。但由于系统参数不可能完全相同，因此实际中当判断L 1f1和L 2f1的差值小于一定阈值时，即ΔL1＝L 1f1-L 2f1＜L set1，可认为金属异物检测时不存在异物。例如，f1＝285kHz时，进行金属异物检测时，ΔL1＝L 1f1-L 2f1，当金属异物检测时不存在金属异物，L 1f1与L 2f1的差值小于一定阈值，ΔL1＝L 1f1-L 2f1＜L set1；当金属异物检测时存在金属异物，L 1f1与L 2f1的差值大于一定阈值，ΔL1＝L 1f1-L 2f1＞L set1。可选的，ΔL1还可以为计算谐振网络302在频率点f1处的输入阻抗L 2f1和预设阻抗L 1f1的差值，即ΔL1＝L 2f1-L 1f1。
S506：计算谐振网络302在频率点f2处的预设阻抗L 1f2和输入阻抗L 2f2的差值ΔL2，ΔL2为频率点f2处的差值阻抗。在控制器304中，比较无金属异物时且恒流源的电流激励频率为 f2时的谐振网络的输入阻抗L 1f2和金属异物检测时且恒流源的电流激励频率为f2时的谐振网络的输入阻抗L 2f2的差ΔL2，ΔL2＝L 1f2-L 2f2。当金属异物检测时不存在金属异物，可以理解的是，理论上L 1f2＝L 2f2，ΔL2＝L 1f2-L 2f2＝0。但由于系统参数不可能完全相同，因此实际中当判断L 1f2和L 2f2的差值小于一定阈值时，即ΔL2＝L 1f2-L 2f2＜L set2，可认为金属异物检测时不存在异物。例如，f1＝285kHz时，进行金属异物检测时，ΔL2＝L 1f2-L 2f2，当金属异物检测时不存在金属异物，L 1f2和L 2f2的差值小于一定阈值，ΔL2＝L 1f2-L 2f2＜L set2；当金属异物检测时存在金属异物，L 1f2和L 2f2的差值大于一定阈值，ΔL2＝L 1f2-L 2f2＞L set2。可选的，ΔL2还可以为计算谐振网络302在频率点f2处的输入阻抗L 2f2和预设阻抗L 1f2的差值，即ΔL1＝L 2f2-L 1f2。
S507：计算频率点f1处的差值阻抗和频率点f2处的差值阻抗的阻抗差的绝对值ΔL，ΔL为总的差值阻抗。在控制器304中，计算频率点f1处的差值阻抗和频率点f2处的差值阻抗的阻抗差的绝对值得到总的差值阻抗，即ΔL＝|ΔL1-ΔL2|。
S508：将ΔL与预先设定的阈值相比较，根据比较结果判断是否存在金属异物。理论上，当不存在金属异物时，ΔL＝|ΔL1-ΔL2|＝0，当存在金属异物时，异物的存在会使感应磁场发生畸变，例如，金属异物在时变磁场中也会被感应出感应电动势，该电动势会在金属异物内部产生闭合回路电流，即涡流，涡流可产生磁场。生物体异物等非金属类异物同样可以使得时变磁场产生畸变，因此本申请实施例也可用于其他非金属类异物的检测应用场景。在一种可能的实现方式中，金属异物产生的涡流磁场会在谐振网络302上产生感应电动势，感应电动势反过来会影响输入阻抗，即在谐振网络302的输入阻抗上叠加异物感应阻抗。如图1所示，从图1可以看出，在谐振频率ωr附近的ω1频率处的两侧，是否存在金属异物两种情况下，谐振电路的阻抗大小是不同的。在频率小于ω1时，有金属异物时检测电路的阻抗大于无金属异物时谐振电路的阻抗；在频率大于ω1时，有金属异物时谐振电路的阻抗小于无金属异物时检测电路的阻抗。但异物感应电压在不同频率处与谐振网络302的输入电压之间的差值的方向与大小均不相同，由此也会导致不同频率处谐振网络的输入阻抗不相同，即ΔL1与ΔL2不相等，ΔL＝|ΔL1-ΔL2|≠0。可以理解的是，实际应用中由于误差的存在，当不存在金属异物时，ΔL也可以不为0。因此为了增加检测精度，可以根据具体工况和误差范围的需要预先设定一个阈值L set。在控制器304中，将总的差值阻抗ΔL与控制器预先设定的阈值进行比较，当ΔL大于预先设定的阈值范围时，即ΔL＝|ΔL1-ΔL2|＞L set，认为存在异物；当ΔL小于预先设定的阈值范围时，即ΔL＝|ΔL1-ΔL2|＜L set，则认为无金属异物。可以理解的是，本申请实施例中在两个频率处测量阻抗差相比在一个频率处测量阻抗差的方法，可以有效提高检测精度，避免误测。
从图1中可以看出，在无金属异物情况和有金属异物两种不同的情况下，由于谐振网络的阻抗特性曲线在谐振频率两侧的差值不同，但公共干扰信号所产生的感应电压在不同频率处可以认为是近似相等的，感应电压所对应的对阻抗造成的变化也是相同的，因此按照上述方法可以有效消除不同复杂工况下出现的公共干扰信号，如发射线圈磁场变化、由于发射线圈和接收线圈间的相对位置不同导致的耦合系数不同等的干扰，提高金属异物检测准确度，减少误判，实现高精度金属异物检测的目的。
例如，当进行金属异物检测时存在发射线圈的磁场变化导致的干扰，无金属异物时且恒流源的电流激励频率为f1时的谐振网络的输入阻抗为L 1f1，发射线圈磁场变化在恒流源的电流激励频率为f1时产生了干扰阻抗Li 1，则在金属异物检测时，恒流源发送频率为f1的电流激励，测量电路303检测到的谐振网络302的输入阻抗应该为L 2f1+Li 1。无金属异物时且恒 流源的电流激励频率为f2时的谐振网络的输入阻抗为L 1f2，发射线圈磁场变化在恒流源的电流激励频率为f2时产生了干扰阻抗Li 2，则在金属异物检测时，恒流源发送频率为f2的电流激励，测量电路303检测到的谐振网络302的输入阻抗应该为L 2f2+Li 2。在控制器304中，比较无金属异物时且恒流源的电流激励频率为f1时的谐振网络的输入阻抗L 1f1，和存在发射线圈的磁场变化导致的干扰时，在恒流源的电流激励频率为f1处进行金属异物检测时的谐振网络的输入阻抗L 2f1+Li 1的差ΔL1，ΔL1＝L 1f1-(L 2f1+Li 1)。比较无金属异物时且恒流源的电流激励频率为f2时的谐振网络的输入阻抗L 1f2，和存在发射线圈的磁场变化导致的干扰时，在恒流源的电流激励频率为f2处进行金属异物检测时的谐振网络的输入阻抗L 2f2+Li 2的差ΔL2，ΔL2＝L 1f2-(L 2f2+Li 2)。在控制器304中，计算f1和f2频率点的总的差值阻抗ΔL＝|ΔL1-ΔL2|。而由于发射线圈的磁场变化所导致的感应电压在不同频率处可以认为是近似相等的，感应电压所对应的对阻抗造成的变化也是相同的，即Li 1＝Li 2。因此当不存在金属异物时，理论上，总的差值阻抗ΔL＝|ΔL1-ΔL2|＝0，可以理解的是，实际上总的差值阻抗ΔL会小于一个阈值，不会存在误判。当存在异物时的总的差值阻抗与没有感应阻抗干扰且存在异物时的总的差值阻抗相同，其阈值设置也可相同，同样不会产生误判。
上述实施例二或三的方法实施例可以应用于实施例一中所描述的异物检测装置中。
可以理解的是，上述实施例中所描述的差值电压或差值电阻中的差值，既可以为包含电压或电阻的方向的实际差值，也可以是处理后的差值，例如实际差值的绝对值。具体情况可以根据实际需要进行设计，本申请不做限制。
本申请实施例四，提供一种可异物检测无线充电发射系统，该可异物检测无线充电发射系统包括实施例一所述的异物检测装置和图4所示的无线充电发射装置，所述异物检测装置用于检测所述无线充电发射系统内是否具有异物，在此不再赘述。
本申请实施例五，提供一种可异物检测无线充电接收系统，该可异物检测无线充电接收系统包括实施例一所述的异物检测装置和图4所示的无线充电接收装置，所述异物检测装置用于检测所述无线充电接收系统内是否具有异物，在此不再赘述。
本申请实施例六，提供一种可异物检测无线充电系统，该可异物检测无线充电系统包括实施例一所述的异物检测装置和图4所示的无线充电发射装置与无线充电接收装置，所述异物检测装置用于检测所述无线充电系统内是否具有异物，在此不再赘述。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件程序实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括至少一个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含至少一个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、光介质(例如，DVD)、或者半导体介质(例如固态硬盘Solid State Disk(SSD))等。
需要说明的是，本申请实施例二或三所提供的方法中各步骤的具体描述可参考上述实施例一的装置实施例中对应内容的具体描述，此处不再一一赘述。另本申请实施例二或三所提 供的方法用于实现上述实施例一中异物检测装置的异物检测功能，因此可以达到与上述实施例相同的效果。
使用本申请实施例所述的异物检测方法、装置或系统，可以消除例如发射线圈的输出功率、输出电压、输出电流变化等发射线圈磁场变化引起的谐振网络的感应电压变化所带来的对异物检测过程的影响，从而提高异物检测的精度，减少误判。
通过以上的实施方式的描述，所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，仅以上述各功能模块的划分进行举例说明，实际应用中，可以根据需要而将上述功能分配由不同的功能模块完成，即将装置的内部结构划分成不同的功能模块，以完成以上描述的全部或者部分功能。
在本申请所提供的几个实施例中，应该理解到，所揭露的装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述模块或单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个装置，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是一个物理单元或多个物理单元，即可以位于一个地方，或者也可以分布到多个不同地方。可以根据实际的需要选择其中的部分或者全部单元来实现本申请实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。
所述集成的单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个可读取存储介质中。基于这样的理解，本申请实施例的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的全部或部分可以以软件产品的形式体现出来，该软件产品存储在一个存储介质中，包括若干指令用以使得一个设备(可以是单片机，芯片等)或处理器(processor)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅是本申请的较佳实施例而已，并非对本申请作任何形式上的限制。虽然本申请已以较佳实施例揭露如上，然而并非用以限定本申请。任何熟悉本领域的技术人员，在不脱离本申请技术方案范围情况下，都可利用上述揭示的方法和技术内容对本申请技术方案做出许多可能的变动和修饰，或修改为等同变化的等效实施例。因此，凡是未脱离本申请技术方案的内容，依据本申请的技术实质对以上实施例所做的任何简单修改、等同变化及修饰，均仍属于本申请技术方案保护的范围内。

Claims (21)

  1. 一种无线充电异物检测方法，其特征在于，所述方法包括：
    获取谐振网络在第一频率处的第一输入电压和第二频率处的第二输入电压，其中所述第一频率小于谐振网络实际谐振频率，所述第二频率大于谐振网络实际谐振频率；
    计算第一差值电压，所述第一差值电压为所述第一预设电压与第一输入电压的差值，所述第一预设电压为无金属异物时所述谐振网络在所述第一频率处的输入电压；
    计算第二差值电压，所述第二差值电压为所述第二预设电压与第二输入电压的差值，所述第二预设电压为无金属异物时所述谐振网络在所述第二频率处的输入电压；
    计算第三差值电压，所述第三差值电压为所述第一差值电压和所述第二差值电压的电压差的绝对值；
    根据所述第三差值电压判断是否存在异物。
  2. 根据权利要求1所述的方法，其特征在于，所述根据所述第三差值电压判断是否存在异物具体包括：
    判断所述第三差值电压是否大于预设阈值，若大于，则判定存在异物。
  3. 根据权利要求1或2所述的方法，其特征在于，在确定所述第一频率和所述第二频率前，所述方法还包括：
    确定所述谐振网络的所述实际谐振频率，所述确定所述谐振网络的所述实际谐振频率具体包括：
    测量所述谐振网络的电感值和电容值，根据所述电感值和所述电容值计算所述谐振网络的所述实际谐振频率；或者，
    对所述谐振网络扫频，测得所述谐振网络输入电压最大时对应的频率为所述谐振网络的所述实际谐振频率。
  4. 根据权利要求1所述的方法，其特征在于，所述第一频率在频率区间[(f-Δf)，f]选取，所述第二频率在频率区间[f，(f+Δf)]选取，所述f为所述谐振网络的实际谐振频率，所述Δf的取值区间为[0.01f，0.5f]。
  5. 根据权利要求1-4任一所述的方法，其特征在于，所述谐振网络包括N个检测线圈，N为大于等于1的整数。
  6. 根据权利要求5所述的方法，其特征在于，所述N个检测线圈中任一检测线圈包括开关，电感元件和电容元件，所述开关与所述电感元件串联，所述电容元件与所述电感元件并联。
  7. 一种无线充电异物检测方法，其特征在于，所述方法包括：
    获取谐振网络在第一频率处的第一输入阻抗和第二频率处的第二输入阻抗，其中所述第一频率小于谐振网络实际谐振频率，所述第二频率大于谐振网络实际谐振频率；
    计算第一差值阻抗，所述第一差值阻抗为所述第一输入阻抗与第一预设阻抗的差值，所述第一预设阻抗为无金属异物时所述谐振网络在所述第一频率处的输入阻抗；
    计算第二差值阻抗，所述第二差值阻抗为所述第二输入阻抗与第二预设阻抗的差值，所述第二预设阻抗为无金属异物时所述谐振网络在所述第二频率处的输入阻抗；
    计算第三差值阻抗，所述第三差值阻抗为所述第一差值阻抗和所述第二差值阻抗的阻抗差的绝对值；
    根据所述第三差值阻抗判断是否存在异物。
  8. 根据权利要求7所述的方法，其特征在于，所述根据所述第三差值阻抗判断是否存在 异物具体包括：
    判断所述第三差值阻抗是否大于预设阈值，若大于，则判定存在异物。
  9. 根据权利要求7或8所述的方法，其特征在于，
    在确定所述第一频率和所述第二频率前，所述方法还包括：
    确定所述谐振网络的所述实际谐振频率，所述确定所述谐振网络的所述实际谐振频率具体包括：
    测量所述谐振网络的电感值和电容值，根据所述电感值和所述电容值计算所述谐振网络的所述实际谐振频率；或者，
    对所述谐振网络扫频，测得所述谐振网络输入电压最大时对应的频率为所述谐振网络的所述实际谐振频率。
  10. 根据权利要求7所述的方法，其特征在于，所述第一频率在频率区间[(f-Δf)，f]选取，所述第二频率在频率区间[f，(f+Δf)]选取，所述f为所述谐振网络的所述实际谐振频率，所述Δf的取值区间为[0.01f，0.5f]。
  11. 根据权利要求7-10任一所述的方法，其特征在于，所述谐振网络包括N个检测线圈，N为大于等于1的整数。
  12. 根据权利要求11所述的方法，其特征在于，所述N个检测线圈中任一检测线圈包括开关，电感元件和电容元件，所述开关与所述电感元件串联，所述电容元件与所述电感元件并联。
  13. 一种无线充电异物检测装置，其特征在于，所述装置包括交流源，谐振网络，测量电路和控制器，其中：
    所述交流源用于提供交流激励；
    所述谐振网络用于检测无线充电发射装置和接收装置之间是否存在异物；
    所述测量电路用于测量所述谐振网络的输入电压；
    所述控制器用于获取谐振网络在第一频率处的第一输入电压和第二频率处的第二输入电压，其中所述第一频率小于谐振网络实际谐振频率，所述第二频率大于谐振网络实际谐振频率；
    计算第一差值电压，所述第一差值电压为所述第一预设电压与第一输入电压的差值，所述第一预设电压为无金属异物时所述谐振网络在所述第一频率处的输入电压；
    计算第二差值电压，所述第二差值电压为所述第二预设电压与第二输入电压的差值，所述第二预设电压为无金属异物时所述谐振网络在所述第二频率处的输入电压；
    计算第三差值电压，所述第三差值电压为所述第一差值电压和所述第二差值电压的电压差的绝对值。
    根据所述第三差值电压判断是否存在异物。
  14. 根据权利要求13所述的检测装置，其特征在于，所述交流源包括恒定交流源。
  15. 根据权利要求13或14所述的检测装置，其特征在于，所述谐振网络包括N个检测线圈，N为大于等于1的整数。
  16. 根据权利要求15所述的检测装置，其特征在于，所述N个检测线圈中任一检测线圈均包括开关，电感元件和电容元件，所述开关与所述电感元件串联，所述电容元件与所述电感元件并联。
  17. 根据权利要求13-16任一所述的检测装置，其特征在于，所述测量电路还用于：
    测量所述谐振网络的输入阻抗。
  18. 根据权利要求13-17任一所述的检测装置，其特征在于，所述控制器还用于：
    获取谐振网络在第一频率处的第一输入阻抗和第二频率处的第二输入阻抗，其中所述第一频率小于谐振网络实际谐振频率，所述第二频率大于谐振网络实际谐振频率；
    计算第一差值阻抗，所述第一差值阻抗为所述第一输入阻抗与第一预设阻抗的差值，所述第一预设阻抗为无金属异物时所述谐振网络在所述第一频率处的输入阻抗；
    计算第二差值阻抗，所述第二差值阻抗为所述第二输入阻抗与第二预设阻抗的差值，所述第二预设阻抗为无金属异物时所述谐振网络在所述第二频率处的输入阻抗；
    计算第三差值阻抗，所述第三差值阻抗为所述第一差值阻抗和所述第二差值阻抗的阻抗差的绝对值；
    根据所述第三差值阻抗判断是否存在异物。
  19. 一种无线充电发射系统，其特征在于，所述无线充电发射系统包括权利要求13-18所述的无线充电异物检测装置和无线充电发射装置，所述无线充电异物检测装置用于检测所述无线充电发射系统内是否具有异物。
  20. 一种无线充电接收系统，其特征在于，所述无线充电接收系统包括权利要求13-18所述的无线充电异物检测装置和无线充电接收装置，所述无线充电异物检测装置用于检测所述无线充电接收系统内是否具有异物。
  21. 一种无线充电系统，其特征在于，所述无线系统包括权利要求13-18所述的无线充电异物检测装置和无线充电装置，所述无线充电异物检测装置用于检测所述无线充电系统内是否具有异物。
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