CN113879145A

CN113879145A - Wireless auxiliary equipment that charges

Info

Publication number: CN113879145A
Application number: CN202111079107.6A
Authority: CN
Inventors: 王哲; 陆钧; 贺凡波; 葛俊杰; 马俊超
Original assignee: Hefei Yougan Technology Co ltd
Current assignee: Hefei Yougan Technology Co ltd
Priority date: 2021-09-15
Filing date: 2021-09-15
Publication date: 2022-01-04

Abstract

The invention discloses a wireless charging auxiliary device, comprising: the working circuit, the switch group and the sensor group are connected to form a loop; the working circuit is formed by connecting a signal generator, a working inductor and a detection unit, and is provided with two access ports; the sensor group is composed of an upper capacitor plate, a substrate and a lower capacitor plate which are sequentially stacked, the upper capacitor plate is connected with one access port of the working circuit through a switch, and the lower capacitor plate is connected with the other access port of the working circuit. The sensor group is used for forming an equivalent capacitor, the equivalent capacitor is connected into the working circuit, and when the metal foreign body is heated, the capacitance value of the equivalent capacitor is influenced, so that the electrical parameters of the working circuit are changed, and the function of detecting the metal foreign body is achieved. To wireless charging, the metal foreign matter is heated the intensification in the electromagnetic field, is main potential safety hazard, and this application can directly utilize the temperature to the influence of capacitance value, and direct efficient discovers the foreign matter, has higher detection precision, receives the environmental disturbance for a short time.

Description

Wireless auxiliary equipment that charges

Technical Field

The invention relates to the field of wireless charging, in particular to wireless charging auxiliary equipment.

Background

When the electric automobile is charged wirelessly, an open space exists between the power transmitting coil and the power receiving coil, foreign matters made of metal materials can enter the space, an alternating magnetic field generated during wireless charging power transmission can generate eddy currents in the metal foreign matters, so that the metal foreign matters are heated to high temperature, potential risks such as burning and burning are caused, and therefore foreign matter detection is a function which must be configured to guarantee safe operation of a wireless charging system.

The most direct method for eliminating the risk caused by the metal foreign matter is to measure the temperature of the surface of the transmitting coil, but a common temperature sensor in the prior art such as a thermal resistor can only measure the temperature of a certain contact point generally, if the arrangement is insufficient, a monitoring blind area can be generated, and the common temperature sensor is basically made of metal material and is also easily influenced by a power transmission magnetic field. Patent CN 110077247A-wireless foreign object detection system and detection method based on optical fiber sensor network proposes a wireless foreign object detection system and detection method based on optical fiber sensor network that can work in magnetic field, but has the problems of low foreign object position resolution and low measurement accuracy. Patent CN 110103745A-a wireless charging metal foreign object detection device and detection method, proposes a device and detection method for detecting the temperature change on the surface of the transmitting coil by exciting the surface acoustic wave to find the foreign object, but the measurement accuracy is also easily affected by factors such as environmental noise and medium composition, so it is still necessary to propose a method for detecting the foreign object to improve the deficiencies of the current technology.

Disclosure of Invention

The invention provides a wireless charging auxiliary device which can accurately detect foreign matters and positions.

Wireless auxiliary equipment that charges includes: the working circuit, the switch group and the sensor group are connected to form a loop; the working circuit is formed by connecting a signal generator, a working inductor and a detection unit, and is provided with two access ports; the sensor group is composed of an upper capacitor plate, a substrate and a lower capacitor plate which are sequentially stacked, the upper capacitor plate is connected with one access port of the working circuit through the switch, and the lower capacitor plate is connected with the other access port of the working circuit.

Preferably, the upper capacitor plate is composed of a plurality of upper grid bars arranged at intervals; the lower capacitor plate consists of a plurality of lower grid bars which are arranged at intervals; the upper grid bars and the lower grid bars are in one-to-one correspondence to form equivalent capacitors.

Preferably, the switch has a plurality of switches, and each of the upper grids is connected to an access port of the working circuit through a switch.

Preferably, the detection unit detects at least a voltage or a frequency.

Preferably, the detection unit includes a working resistor connected in series to the working circuit and a detector for detecting an electrical parameter of the working resistor.

Preferably, a loop formed by the working circuit, the switch group and the sensor group forms an oscillating circuit; the frequency and the variation range of the oscillating circuit are different from the wireless charging working frequency.

Preferably, the sensor group is arranged on a power transmitting coil of the wireless charging system, and the coverage range is greater than or equal to the range of the power transmitting coil.

Preferably, the sensor group is used as an upper shell of the wireless charging system.

Preferably, the substrate is made of a sheet material with a high dielectric constant, and the dielectric constant changes with temperature; the high dielectric constant sheet material comprises: at least one of ferroelectric ceramic, aluminum oxide and barium carbonate.

The wireless charging auxiliary equipment can form an equivalent capacitor through the sensor group, is connected into the working circuit, and influences the capacitance value of the equivalent capacitor when the metal foreign body is heated, so that the electrical parameter of the working circuit is changed, and the detection function of the metal foreign body is achieved. To wireless charging, the metal foreign matter is heated the intensification in the electromagnetic field, is main potential safety hazard, and this application can directly utilize the temperature to the influence of capacitance value, and direct efficient discovers the foreign matter, has higher detection precision, receives the environmental disturbance for a short time.

Drawings

Fig. 1 is a schematic diagram of the operation of a wireless charging system;

FIG. 2 is a schematic diagram of a wireless charging accessory of the present invention;

FIG. 3 is an exploded view of the transmitting end;

fig. 4 is a schematic diagram of a sensor group in the wireless charging auxiliary device according to the present invention.

Reference numerals:

an operating circuit 1; a sensor group 3; a receiving end 8; a transmitting end 9; a signal generator 11; a working inductance 12; a detection unit 13; an upper capacitor plate 31; a substrate 32; a lower capacitor plate 33; an electrode 34; an upper case 91; a coil winding 92; a soft magnetic material plate 93; a metallic shield plate 94; a lower case 95; a working resistance R; a detector M; a switch group K; .

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative only and should not be construed as limiting the invention.

The invention provides a wireless charging auxiliary device which is mainly used for foreign matter detection, temperature monitoring and the like.

For convenience of description, the following description will be given by taking wireless charging of an electric vehicle as an example, but it should be emphasized that the wireless charging auxiliary device of the present application is not only applicable to wireless charging of vehicles, for example, wireless charging of mobile phones, wireless charging of unmanned aerial vehicles, and the like, but also applicable to the auxiliary device of the present application.

Referring to fig. 1, a wireless charging of an electric vehicle is taken as an example for an overall description. Wireless system is including installing transmitting terminal 9 on ground and installing the receiving terminal 8 in the car bottom, the power transmitting coil of transmitting terminal 9 passes through power controller and is connected to power supply, pass through transmitting coil after the power frequency alternating current converts high frequency alternating current, turn into the magnetic field with the electric energy, its accessible air propagation, after the magnetic field was received to the power receiving coil of receiving terminal 8, because electromagnetic induction can produce the electric current in receiving coil, and then convert the direct current into and charge for power battery, finally realize the wireless transmission of electric energy from power to battery.

In the wireless charging process, if a metal foreign body exists between the power transmitting coil and the power receiving coil, the metal foreign body is heated by a magnetic field, and potential safety hazards are generated. The wireless auxiliary equipment that charges of this application just can in time discover these potential safety hazards.

The wireless charging auxiliary equipment comprises a working circuit 1, a switch group K and a sensor group 3, and the three parts are connected through lines to form a loop. The sensor group 3 is arranged at the transmitting end 9, typically above the power transmitting coil. As shown in fig. 2, which is an exploded view of the transmitting terminal 9, it comprises an upper case 91, a coil winding 92 (power transmitting coil), a soft magnetic material plate 93, a metal shielding plate 94 and a lower case 95, and the sensor group 3 of the wireless charging auxiliary device of the present application is provided between the upper case 91 and the coil winding 92. The components of the operating circuit 1 and the switch group K may be located on the lower side of the metal shield plate 94, or may not be provided between the upper case 91 and the lower case 95. Their specific setting positions can be adjusted according to actual requirements. In one embodiment, the sensor group 3 can be directly used as the upper housing 91, i.e. the sensor group 3 and the upper housing 91 are integrated in fig. 2.

The upper case 91 and the lower case 95 are mainly used to encapsulate the entire structure, improving mechanical strength and sealability. The two parts are generally made of non-metal materials, such as ABS engineering plastics, SMC thermosetting plastics and the like. The coil windings 92 are typically wound from high frequency litz wire. The upper casing 91 and the lower casing 95 may be made of different materials, so that at least the upper casing 91 has good thermal conductivity while ensuring strength, and the temperature of the surface can be transmitted to the sensor group 3. The sensor group 3 can also be arranged directly on the uppermost layer as the upper housing 91 and become the surface of the transmitting coil. The soft magnetic material plate 93 is generally made of ferrite material and plays a role in guiding the magnetic field direction and shielding magnetic field leakage during wireless charging, the soft magnetic material plate 93 is positioned below the coil winding 92, the metal shielding plate 94 is installed below the soft magnetic material plate 93, and the metal shielding plate 94 is generally a thin plate made of metal aluminum and plays roles in electromagnetic field shielding and heat conduction.

The processor in the wireless charging auxiliary device can be independently arranged, or can be used as a part of a transmitting end controller of the wireless charging system, and the transmitting end controller is generally arranged in the cabinet body outside the transmitting coil.

After the transmitting end is assembled, epoxy resin pouring sealant can be filled in the transmitting end, and the effects of curing, insulating, heat conducting, water proofing and the like on the coil structure are achieved.

The structure of the wireless charging assist apparatus is explained in detail below. As shown in fig. 3 and 4, the working circuit 1 is formed by connecting a signal generator 11, a working inductor 12 and a detection unit 13, and the working circuit 1 has two access ports; the sensor group 3 is composed of an upper capacitor plate 31, a substrate 32 and a lower capacitor plate 33 which are sequentially stacked, the upper capacitor plate 31 is connected with one access port of the working circuit 1 through the switch K, and the lower capacitor plate 33 is connected with the other access port of the working circuit 1.

The sensor group 3 is simply understood to be formed by the upper capacitor plate 31, the substrate 32 and the lower capacitor plate 33 to form an equivalent capacitance, the capacitance value Cx of which may change with temperature. The sensor group 3 can entirely cover a range in which foreign object detection is required.

For convenience of description, the upper capacitor plate 31 and the lower capacitor plate 33 are collectively referred to as a capacitor plate. The capacitor plate of the equivalent capacitor is generally in a complete shape, but each equivalent capacitor is in a wireless charging power transmission magnetic field, in order to reduce the eddy current effect generated by the capacitor plate, the capacitor plate is provided with a plurality of grid bars which are uniformly arranged at intervals, and the length of each grid bar is not limited, but has the minimized thickness and width. Namely, the upper capacitor plate 31 is composed of a plurality of upper grids arranged at intervals; the lower capacitor plate 32 is composed of a plurality of lower grid bars arranged at intervals; the upper grid bars are in one-to-one correspondence with the lower grid bars. That is, the upper capacitor plate 31, the substrate 32 and the lower capacitor plate 33 may form a plurality of equivalent capacitors, each of which is independent of the other, and a structure in which these plurality of equivalent capacitors are combined together is referred to as an equivalent capacitor unit. For purposes of illustration, upper capacitive plate 31 and lower capacitive plate 33 are collectively referred to as capacitive plates. The above-mentioned "grid bars" are used to describe the state that the capacitor plate is divided into a plurality of independent parts, that is, the mechanism composed of all the upper grid bars is the upper capacitor plate 31. If the number of the upper grid bars is one, the upper capacitor plate 31 is a whole. The same applies to the lower capacitor plates 33 and the lower grid bars.

Regardless of the number of equivalent capacitances formed, the capacitance Cx and the dielectric constant of the material for these equivalent capacitances are related as follows:

Cx＝ε₀ε_rs/d … … … … … … … … … … … … formula 1

Wherein epsilon₀Is vacuum absolute dielectric constant (8.85 × 10)^-12F/m)，ε_rFor the dielectric constant of the dielectric material between the upper capacitor plate and the lower capacitor plate, which is related to the temperature, S is the area of the capacitor plate, and for the grid divided into a plurality of grids, S is equal to the total area of the grids, which of course needs to be considered as to which part of the capacitance value of the capacitor is calculated, for example, the capacitance value of the equivalent capacitor formed by only one set of grids is calculated, then S is the area of the grids of the equivalent capacitor, if the capacitance value of the entire equivalent capacitor is calculated, then the total area of all the grids is calculated, and d is the distance between the capacitor plates.

A substrate 32 is disposed between the upper capacitor plate 31 and the lower capacitor plate 33, the substrate 32 is a thin plate made of a ceramic material having a high dielectric constant, such as ferroelectric ceramic, alumina, barium carbonate, etc., and er is the dielectric constant of the substrate 32, which varies with temperature.

The grid bars can be made of copper foil, aluminum foil, etc., that is, the upper capacitor plate 31 and the lower capacitor plate 33 can be made of these materials.

The plate thickness has no effect on the capacitance of the equivalent capacitor according to relation 1, and therefore it is preferred to make the thin film grid from a conductive polymer, metal oxide or carbon material, deposited on the substrate 32 to achieve a minimum thickness. I.e., on opposite sides of substrate 32, to form upper capacitor plate 31 and lower capacitor plate 33, respectively. An electrode 34 is connected to the grid for connection to the switch K or the operating circuit 1.

The grid bars which are opposite up and down and the substrate 32 between the grid bars form equivalent capacitance, the electrodes 34 of the grid bars on the same side are connected with each other, and the upper electrode and the lower electrode of an equivalent capacitance unit are respectively formed up and down, so that the equivalent capacitance unit is formed by connecting a plurality of equivalent capacitances in parallel. The connecting line of the equivalent capacitance unit and the working circuit is generally made of metal materials and is exposed in the power transmission magnetic field, and the connecting line has minimized thickness and width in order to minimize eddy current loss.

The detection unit 13 in the working circuit 1, the detection unit 13 can detect electric signals such as voltage or frequency. Preferably, it includes a working resistor R and a detector M, and the general detector M is used to detect the voltage of the working resistor R. As shown in fig. 1, the detector is connected to two locations AB for obtaining the voltage value across the working resistor R.

The working circuit 1 is composed of a detection unit 13, a working inductor 12 and a signal generator 11, and of course, a processor (not shown in the figure) for processing information is included, and for convenience of understanding, taking fig. 1 as an example, the detection unit 13 includes a working resistor R and a detector M. Wherein the processor can obtain A, B the voltage signal between the two points, control the switch set K and the signal generator 11. One electrode 34 of one equivalent capacitor in each equivalent capacitor unit is connected with one switch in the switch group K, and the other electrode 34 is connected with the working circuit. In fig. 1, to show the switches connected by each of the equal small capacitors, each switch in the switch group K is denoted by K1, K2 … … Kn, respectively.

The switch group K is controlled by the processor to be switched into the equivalent capacitors in a circulating mode, one equivalent capacitor which is connected into the equivalent capacitor units each time is connected with the working circuit, and the processor measures parameters of the equivalent capacitor units in a time-sharing mode.

When one switch of the switch group K is switched on, one equivalent capacitor of the sensor group 3 is connected with the working circuit 1, and the connected equivalent capacitor single-working inductor 12 forms an LC series resonance circuit. In the embodiment of fig. 1, a working resistor R is included, which forms an LCR series resonant circuit.

The signal generator 11 applies a set of alternating current signals with variable frequency in the working circuit 1, the signal generator adjusts the output signal to enable the voltage amplitude to be unchanged and the frequency to be changed, the detector M measures the voltage at two ends of the resistor R (namely two ends of A, B) and sends the voltage to the processor, when the frequency is changed to a certain value, the inductive reactance and the capacitive reactance in the working circuit can be mutually counteracted, the working circuit generates series resonance, namely the frequency of the output signal is consistent with the resonance frequency of the working circuit. At this time, the phases of the equivalent capacitor and the working inductor 12 complement each other, and the working resistor R is divided into maximum voltage values. That is, when the maximum voltage is obtained at the upper side of the operating resistor R, it indicates that the frequency of the ac signal applied by the signal generator 11 in the operating circuit 1 at this time is the resonant frequency of the operating circuit 1. From the knowledge of the resonant circuit, it can be seen that the resonant frequency f of an LCR series circuit is determined by the inductance L and the capacitance C and has the relationship 2:

for the working circuit, where Cx is the capacitance of an equivalent capacitor connected in and Lx is the inductance of the working inductor 12. The method for measuring the frequency is an embodiment, and may be obtained by measuring and analyzing parameters such as phase and impedance of the operating circuit 1. It should be noted that the above-mentioned working resistor R is used for measuring voltage, and corresponding components should be used if other types of data are to be tested.

By knowing the resonant frequency and the inductance of the working inductor 12, the capacitance of the equivalent capacitor can be obtained.

According to the relation 1, when the dielectric constant of the substrate 32 changes due to the temperature change in the equivalent capacitor unit, the capacitance value will also change with the change of the dielectric constant, and finally the resonant frequency will change nearly linearly with the change of the temperature. That is, the capacitance value of the equivalent capacitor is obtained through the resonant frequency, and then the corresponding temperature is obtained through the capacitance value.

The influence of temperature on the dielectric constant is related to the material, for the equivalent capacitance of the determined material, the resonant frequency corresponding to different temperatures can be collected in advance, the change data of the temperature and the resonant frequency is calibrated, the change relational expression of the resonant frequency along with the temperature can be obtained by linear fitting, and the temperature of the capacitance plate of the equivalent capacitance can be measured by the working circuit through measuring the resonant frequency. The inductance of the working inductor 12 of the working circuit is a fixed value, and when the capacitance of the equivalent capacitor changes, the resonant frequency will have a certain range of change.

The inductance value of the operating inductor is set to vary the frequency of the operating circuit and the frequency, both of which are in different ranges from the wireless charging operating frequency. Of course, this also needs to ensure the capacitance range of the equivalent capacitance. Therefore, when selecting the working inductor 12 and selecting the material of the sensor group 3, it is necessary to verify each other to ensure the capacitance variation range in the sensor group 3 and the inductance value of the working inductor 12, and not to make the frequency of the working circuit and the frequency of the wireless charging operation coincide and affect each other, that is, to ensure the capacitance variation range and the inductance value of the working inductor 12 at the same time, so that the resonant frequency obtained by using equation 2 does not affect the frequency of the wireless charging operation.

When the dielectric constant of the substrate material changes due to the temperature change of the equivalent capacitance unit, the dielectric constant of the equivalent capacitance unit changes with the temperature change, and further changes the capacitance value Cx of the equivalent capacitance unit, according to the formula 1 and the formula 2, when the wireless charging system is at the lowest temperature (the lowest temperature here generally refers to the temperature when the wireless charging system is not in operation, and may be the lowest ambient temperature at which the system can operate), the measured frequency is the maximum value of the resonance frequency, the signal generator 11 may use the corresponding frequency as the maximum value of the frequency change range, and when detecting a foreign object, the output frequency is continuously reduced, and the voltage at two ends of the resistor R is measured.

When the wireless charging is carried out, if a metal foreign matter falls into the working range, the metal foreign matter is exposed in the power transmission magnetic field of the wireless charging, the temperature of the metal foreign matter can be increased due to the eddy current effect, and the temperature increase can be transmitted to one or more equivalent capacitors of the sensor group 3, so that the capacitance value is changed. When detecting the wireless charging foreign object, the signal generator 11 outputs an alternating current signal with a varying frequency, the working circuit 1 obtains a resonant frequency (for example, measuring a terminal voltage of the working resistor R) through the detection unit 13, and the variation of the capacitance value influenced by the temperature finally influences the variation of the resonant frequency, so that the measured variation of the resonant frequency can calculate the capacitance value of the equivalent capacitance after the temperature variation, and measure the temperature of the equivalent capacitance. And comparing the measured temperature with a temperature reference value, judging that the metal foreign matter exists above the transmitting coil when the measured temperature exceeds the reference value within a certain range, and determining the position of the metal foreign matter above the transmitting coil according to the position of the equivalent capacitor with the temperature rise. To be able to determine this position, the sensor group 3 is arranged, typically on top of the power transmitting coil of the wireless charging transmitting terminal, and it is possible that the coverage of the sensor group 3 is not smaller than the range of the transmitting coil.

As an embodiment, the switch group K may simultaneously turn on a plurality of switches at a time to connect a plurality of equivalent capacitors or all equivalent capacitors of the sensor group 3 to the operating circuit 1, and at this time, the equivalent capacitors or all equivalent capacitors are connected in parallel, and when the temperature changes, the sum of the equivalent capacitors or all equivalent capacitors changes, and as with the above principle, a relational expression between the resonance frequency and the temperature based on the sum of the capacitors is established, and the temperature change is obtained from the change of the sum of the capacitors. Similarly, when the measured temperature exceeds the temperature reference value, it can be determined that a metallic foreign object exists at a certain position in the region where the plurality of equivalent capacitors are located above the radiation ring. When all the equivalent capacitors are connected with the working circuit 1 and the measured temperature exceeds the temperature reference value, it can be judged that a metal foreign matter exists at a position above the radiation ring. After the metal foreign matter is found, the switch group K selects one or more equivalent capacitors from the equivalent capacitors with the foreign matter to be connected into the working circuit again, but the connection number of the equivalent capacitors is smaller than that of the equivalent capacitors with the foreign matter, the steps are operated circularly, the number of the equivalent capacitors connected each time is reduced step by step until only one equivalent capacitor is connected each time, and finally, the equivalent capacitor or capacitors with the metal foreign matter are determined, and the area where the equivalent capacitor or capacitors are located is the position where the metal foreign matter is located. Different from the foregoing embodiment, the above operation first quickly determines whether the metal foreign object exists, so that the wireless charging system can respond in time, and then gradually determines the position of the metal foreign object.

Once the metal foreign matter is detected to exist, the wireless charging system can reduce power transmission or directly close power transmission, and sends an alarm to report a foreign matter detection fault, and prompts a user to remove the metal foreign matter.

Before the wireless charging system is started, detection before formal charging can be carried out, firstly, low-power energy is applied to the power transmitting coil to start trial charging, when the temperature of the equivalent capacitor is found to exceed the reference temperature, an alarm is sent to report a foreign matter detection fault, a user is prompted to remove the metal foreign matter, and low-power charging is stopped. If metal foreign matters are found in the charging process and faults are eliminated after alarming, the state of detection before charging can be entered again, the state of normal charging is recovered, and the foreign matter detection process is repeated.

The construction, features and functions of the present invention are described in detail in the embodiments illustrated in the drawings, which are only preferred embodiments of the present invention, but the present invention is not limited by the drawings, and all equivalent embodiments modified or changed according to the idea of the present invention should fall within the protection scope of the present invention without departing from the spirit of the present invention covered by the description and the drawings.

Claims

1. A wireless charging accessory device, comprising:

the working circuit (1), the switch group (K) and the sensor group (3) are connected to form a loop;

the working circuit (1) is formed by connecting a signal generator (11), a working inductor (12) and a detection unit (13), and the working circuit (1) is provided with two access ports;

the sensor group (3) is composed of an upper capacitor plate (31), a substrate (32) and a lower capacitor plate (33) which are sequentially stacked, the upper capacitor plate (31) is connected with one access port of the working circuit (1) through the switch (K), and the lower capacitor plate (33) is connected with the other access port of the working circuit (1).

2. The wireless charging accessory of claim 1,

the upper capacitor plate (31) is composed of a plurality of upper grid bars which are arranged at intervals;

the lower capacitor plate (32) is composed of a plurality of lower grid bars which are arranged at intervals;

the upper grid bars and the lower grid bars are in one-to-one correspondence to form equivalent capacitors.

3. The wireless charging accessory of claim 2,

the switches (K) are provided with a plurality of switches, and each upper grid bar is connected into one access port of the working circuit (1) through one switch (K).

4. The wireless charging accessory of claim 1,

the detection unit (13) detects at least a voltage or a frequency.

5. The wireless charging accessory of claim 4,

the detection unit (13) comprises a working resistor (R) connected in series with the working circuit (1) and a detector for detecting an electrical parameter of the working resistor (R).

6. The wireless charging accessory of claim 1,

a loop formed by the working circuit (1), the switch group (K) and the sensor group (3) forms an oscillating circuit; the frequency and the variation range of the oscillating circuit are different from the wireless charging working frequency.

7. The wireless charging accessory of claim 1,

the sensor group (3) is arranged on a power transmitting coil of a wireless charging system, and the coverage range is larger than or equal to the range of the power transmitting coil.

8. The wireless charging accessory of claim 1,

the sensor group (3) serves as an upper shell (91) of the wireless charging system.

9. The wireless charging accessory of claim 1,

the substrate (32) is made of a high-dielectric-constant sheet material, and the dielectric constant changes with temperature;

the high dielectric constant sheet material comprises: at least one of ferroelectric ceramic, aluminum oxide and barium carbonate.