CN114709935A - Wireless charging system of wireless power transmission system and wearable device - Google Patents

Abstract

The application discloses wireless power transmission system, wireless charging system of wearing formula equipment relates to power transmission technical field, includes: the device comprises a transmitting end module and a receiving end module, wherein the transmitting end module comprises a direct-current voltage input module, an E-class inverter module, a first filtering module, a capacitance dynamic compensation module and a transmitting coil module which are sequentially and electrically connected, and the capacitance dynamic compensation module is used for realizing capacitance compensation on the transmitting coil module; the receiving end module comprises a receiving coil module, a rectifying and filtering module and a load which are electrically connected with each other, and the receiving coil module is electrically coupled with the transmitting coil module. The application can realize long-distance and high-efficiency energy transmission.

Description

Wireless charging system of wireless power transmission system and wearable device

Technical Field

The application relates to the technical field of electric energy transmission, in particular to a wireless charging system of a wireless electric energy transmission system and wearable equipment.

Background

The wireless power transmission technology is also called wireless power transmission and non-contact power transmission, and refers to a transmission mode in which electric energy is converted into relay energy in other forms (such as electromagnetic field energy, laser, microwave, mechanical wave and the like) by a transmitter, and after the relay energy is transmitted for a certain distance, the relay energy is converted into electric energy by a receiver, so that wireless power transmission is realized. The technology can realize the electrical isolation between the power supply and the load, thereby avoiding the generation of electric arcs, and has the advantages of water resistance, convenience and the like, so that the technology is developed rapidly. At present, a magnetic field coupling type wireless power transmission technology is relatively perfect and can be commercially used, namely, a magnetic field is coupled from a transmitting coil to a receiving coil through an electromagnetic induction principle. However, the current wireless power transmission technologies all have the disadvantage of short transmission distance.

Disclosure of Invention

The present application is directed to solving at least one of the problems in the prior art. Therefore, the application provides a wireless power transmission system and a wireless charging system of wearable equipment, and long-distance and high-efficiency energy transmission can be realized.

In a first aspect, the present application provides a wireless power transmission system, including:

the system comprises a transmitting end module, a receiving end module and a transmitting terminal module, wherein the transmitting end module comprises a direct-current voltage input module, an E-type inverter module, a first filtering module, a capacitance dynamic compensation module and a transmitting coil module which are sequentially and electrically connected, and the capacitance dynamic compensation module is used for realizing capacitance compensation on the transmitting coil module;

the receiving end module comprises a receiving coil module, a rectifying and filtering module and a load which are mutually and electrically connected, and the receiving coil module is electrically coupled with the transmitting coil module.

According to the wireless power transmission system of the embodiment of the first aspect of the application, at least the following beneficial effects are achieved: before carrying out wireless power transmission, can adjust the direct current voltage size of direct current voltage input module according to the load demand, direct current signal is accurate sinusoidal wave of high frequency through class E inverter module conversion direct current signal, and this accurate sinusoidal wave of high frequency is higher than 1MHz usually and is 6.78MHz and 13.56MHz, and wherein, the wireless power transmission system of work at 13.56 MHz's NFC technique can realize centimetre level coupling distance and degree of freedom. High frequency quasi sine wave filters wherein high frequency noise through first filtering module afterwards, be sent into electric capacity dynamic compensation module afterwards, select the electric capacity compensation volume according to concrete actual load and coupling condition, with compensation to transmitting coil module, and through transmitting coil module with the electric energy in order to convert magnetic field energy into, convert into high frequency alternating current electric energy after receiving this magnetic field energy through receiving coil module of receiving terminal afterwards, high frequency alternating current electric energy converts direct current supply into for the load through rectification filtering module, this application combines through the high frequency quasi sine wave and first filtering module of E class inverter module conversion, electric capacity dynamic compensation module and high frequency NFC communication technology, can realize at high frequency, remote under wide load range and the coupling change condition, high efficiency energy transmission.

According to some embodiments of the first aspect of the present application, the class-E inverter module includes a first inductor, a first switch, a first capacitor, a second inductor, and a second capacitor, one end of the first inductor is electrically connected to the positive terminal of the dc voltage input module, and the other end is electrically connected to one end of the first switch, one end of the first capacitor, and one end of the second capacitor, respectively, the other end of the first switch, the other end of the first capacitor, and the negative terminal of the dc voltage input module are electrically connected, and the other end of the second capacitor is connected to one end of the second inductor.

According to some embodiments of the first aspect of the present application, the second inductor is a shared element of the class E inverter module and the first filter module, the first filter module further includes a third capacitor, another end of the second inductor is electrically connected to one end of the dynamic capacitance compensation module and another end of the third capacitor, respectively, and another end of the third capacitor is electrically connected to the negative electrode of the dc voltage input module.

According to some embodiments of the first aspect of the present application, the dynamic capacitance compensation module includes a first compensation branch and a second compensation branch, the first compensation branch includes a first switch component and a fourth capacitance, the second compensation branch includes a second switch component and a fifth capacitance, one end of the first switch component and one end of the second switch component are both electrically connected to the first filtering module, the other end of the first switch component is electrically connected to one end of the fourth capacitance, the other end of the second switch component is electrically connected to one end of the fifth capacitance, and the other end of the fourth capacitance and the other end of the fifth capacitance are both connected to the transmitting coil module.

According to some embodiments of the first aspect of the present application, the capacitance dynamic compensation module further includes at least one third compensation branch, and two ends of the third compensation branch are electrically connected to the first filtering module and the transmitting coil module, respectively.

According to some embodiments of the first aspect of the present application, the transmitting coil module includes a third inductor and a sixth capacitor, one end of each of the third inductor and the sixth capacitor is electrically connected to the first filter module, and the other end of each of the third inductor and the sixth capacitor is electrically connected to the negative terminal of the dc voltage input module.

According to some embodiments of the first aspect of the present application, the receiving coil module includes a fourth inductor and a seventh capacitor, and two ends of the fourth inductor and two ends of the seventh capacitor are electrically connected to two input ends of the rectifying and filtering module, respectively.

According to some embodiments of the first aspect of the present application, the receiving coil module further includes an eighth capacitor, one end of the eighth capacitor is electrically connected to the fourth inductor and the seventh capacitor, and the other end of the eighth capacitor is electrically connected to one input end of the rectifying and filtering module.

According to some embodiments of the first aspect of the present application, the power supply further includes an eighth capacitor, one end of the ninth capacitor is electrically connected to one output end of the rectifying and filtering module and one end of the load, and the other end of the ninth capacitor is electrically connected to the other output end of the rectifying and filtering module and the other end of the load.

In a second aspect, the present application further provides a wireless charging system for a wearable device, including:

a wireless power transfer system as described in any one of the embodiments of the first aspect;

the first driving and communication module is electrically connected with the E-type inverter module and the transmitting coil module respectively;

the first master control chip is electrically connected with the first driving and communication module, the direct-current voltage input module and the capacitance dynamic compensation module respectively;

the second communication module is electrically connected with the receiving coil module and the rectification filtering module respectively;

and the second main control chip is respectively and electrically connected with the second communication module and the load.

According to the wireless charging system of the wearable device in the embodiment of the second aspect of the application, at least the following beneficial effects are achieved: after a transmitting end module, namely a wireless charger, is connected to a power supply to supply power, a wireless charging system starts self-checking; after the self-checking is passed, the first main control chip sets an initial voltage for the direct-current voltage input module, and switches on the capacitor dynamic compensation module to set an initial compensation capacitor; the first main control chip sends a command to the first driving and communication module, so that the module outputs a fixed-frequency PWM wave at intervals to drive the first switch, and the system enters a standby state; after the wearable device is placed on the charger, namely after the receiving end module is connected with the load, the second main control chip collects information such as device ID, battery voltage and the like and stores the information in the second communication module; the first driving and communication module detects the existence of equipment detected through in-band communication, reads equipment information in the second communication module and sends the equipment information to the first main control chip; the first main control chip completes system configuration according to the information and starts energy transmission; the first main control chip selects proper direct-current voltage input module voltage and capacitance compensation of the capacitance dynamic compensation module according to information such as output voltage requirements and the like to adjust power; the second main control chip continuously updates information such as output voltage, battery capacity and the like and stores the information in the second communication module; the first driving and communication module reads related information such as output voltage of the receiving end at intervals and sends the related information to the first main control chip; and repeating the charging detection step until the charging is finished or equipment failure occurs, and the like, wherein the first main control chip makes judgment according to the received information and enters the standby state again. Through the wireless charging system, long-distance and high-efficiency energy transmission under the conditions of high frequency, wide load range and coupling change can be realized.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

Additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a block diagram of a wireless power transfer system of some embodiments of a first aspect of the present application;

fig. 2 is a circuit schematic diagram of a wireless power transfer system of some embodiments of the first aspect of the present application;

fig. 3 is a circuit schematic diagram of a wireless charging system of a wearable device of some embodiments of the second aspect of the present application.

Detailed Description

Reference will now be made in detail to embodiments of the present application, 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 exemplary only for the purpose of explaining the present application and are not to be construed as limiting the present application.

In the description of the present application, it is to be understood that the positional descriptions, such as the directions of up, down, front, rear, left, right, etc., referred to herein are based on the directions or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, and do not indicate or imply that the referred device or element must have a specific direction, be constructed and operated in a specific direction, and thus, should not be construed as limiting the present application.

In the description of the present application, if there are first and second descriptions for distinguishing technical features, the description should not be interpreted as indicating or implying any relative importance or implying any number of indicated technical features or implying any precedence over indicated by the indicated technical features.

In the description of the present application, unless otherwise specifically limited, terms such as set, installed, connected and the like should be understood broadly, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present application in combination with the specific contents of the technical solutions.

The wireless power transmission technology is also called wireless power transmission or non-contact power transmission, and refers to a transmission mode in which electric energy is converted into relay energy of other forms (such as electromagnetic field energy, laser, microwave, mechanical wave and the like) by a transmitter, and after the relay energy is transmitted for a certain distance, the relay energy is converted into electric energy by a receiver, so that wireless power transmission is realized. The technology can realize the electrical isolation between the power supply and the load, thereby avoiding the generation of electric arcs, and has the advantages of water resistance, convenience and the like, so that the technology is developed rapidly. At present, magnetic field coupling type wireless power transmission technology, namely, coupling a magnetic field from a transmitting coil to a receiving coil through an electromagnetic induction principle, is relatively perfect and can be commercially used.

The Class-E architecture is a simple single-switch converter suitable for high-frequency applications, and has recently been applied to magnetic field coupling wireless power transmission scenarios.

NFC is an emerging near field communication technology, and devices using the NFC technology can exchange data when they are close to each other, and implement applications such as mobile payment, electronic ticketing, door access, mobile identity recognition, and anti-counterfeiting by using a mobile terminal. The technology is gradually applied to the field of wireless power transmission because the technology has induction distance and flexibility which can reach 10cm when the technology operates in a high-frequency industrial, scientific and medical frequency band of 13.56 MHz.

Wireless power transmission systems based on the magnetic field coupling principle generally require an increase in the operating frequency of the system within a limited structural space and input voltage in order to increase transmission distance and transmission power. However, the conventional full-bridge/half-bridge/single-tube inverter and the compensation methods such as series/parallel/LCL are not suitable for high frequency operation, resulting in reduced efficiency and increased EMI. In addition, due to the influence of barrier capacitance and diffusion capacitance of the transistor for the inverter switch and distributed capacitance in the circuit, the transistor needs a certain switching time from saturation to cutoff or from cutoff to saturation. Higher operating frequencies can reduce switching efficiency and even damage the device.

Although the system can work in a quasi-resonant soft switching state by adopting a conventional Class-E inverter, the peak voltage at two ends of a switch and the peak current flowing through the switch are large and are limited by a limited load working range. The load at the receiving end of the wireless power transmission system is often switched between no load and full load, and the mutual inductance is changed along with the change of the coupling state. Therefore, the load variation range of the transmitting end can exceed the working range of a Class-E inverter, so that the system is detuned to stop working, and a switch or other devices are burnt out.

Although the wireless power transmission system adopting the NFC technology working at 13.56MHz can realize centimeter-level coupling distance and freedom degree. However, the existing system can only achieve the output power of 1W at most due to the limitation of chip capability and EMI.

In a first aspect, referring to fig. 1, the present application provides a wireless power transmission system, including: the system comprises a transmitting end module 100 and a receiving end module 200, wherein the transmitting end module comprises a direct-current voltage input module 110, an E-class inverter module 120, a first filtering module 130, a dynamic capacitance compensation module 140 and a transmitting coil module 150 which are sequentially and electrically connected, and the dynamic capacitance compensation module 140 is used for realizing capacitance compensation on the transmitting coil module 150; the receiving end module 200 includes a receiving coil module 210, a rectifying and filtering module 220, and a load 230 electrically connected to each other, wherein the receiving coil module 210 is electrically coupled to the transmitting coil module 150. Before carrying out wireless power transmission, can adjust the DC voltage size of DC voltage input module 110 according to the load 230 demand, DC signal converts DC signal into high frequency quasi-sine wave through class E inverter module 120, and this high frequency quasi-sine wave is higher than 1MHz usually and is 6.78MHz and 13.56MHz often, and wherein, the coupling distance and the degree of freedom of centimetre level can be realized to the wireless power transmission system of work in 13.56 MHz's NFC technique. Then, the high-frequency quasi-sinusoidal wave filters high-frequency noise therein through the first filtering module 130, and then is sent into the dynamic capacitance compensation module 140, a capacitance compensation amount is selected according to a specific actual load 230 and a coupling condition to compensate to the transmitting coil module 150, electric energy is converted into magnetic field energy through the transmitting coil module 150, the magnetic field energy is received through the receiving coil module 210 at a receiving end and then converted into high-frequency alternating current energy, the high-frequency alternating current energy is converted into direct current through the rectifying and filtering module 220 and supplied to the load 230, and the high-frequency quasi-sinusoidal wave is converted into the high-frequency quasi-sinusoidal wave through the class-E inverter module 120, and the high-frequency quasi-sinusoidal wave, the first filtering module 130, the dynamic capacitance compensation module 140 and a high-frequency NFC communication technology are used for realizing remote and high-efficiency energy transmission in a high-frequency and wide load 230 range and a coupling change condition.

It should be noted that, the dc voltage input module 110 is a voltage source portion labeled Vin in fig. 2, and the load 230 is a portion labeled Rload in fig. 2.

Referring to fig. 2, it can be understood that the class E inverter module 120 includes a first inductor L1, a first switch S1, a first capacitor C1, a second inductor L2, and a second capacitor C2, one end of the first inductor L1 is electrically connected to the positive terminal of the dc voltage input module 110, the other ends of the first inductor L1, the first capacitor C1, and the second capacitor C2 are electrically connected to one end of the first switch S1, one end of the first capacitor C1, and one end of the second capacitor C2, the other end of the first switch S1 and the other end of the first capacitor C1 are both electrically connected to the negative terminal of the dc voltage input module 110, and the other end of the second capacitor C2 is connected to one end of the second inductor L2. Specifically, the first inductor L1 is a dc inductor, and converts a voltage source into a constant current source; the first switch S1 is a MOSFET or GaN switch for converting dc power to high-frequency ac power, in this embodiment, the first switch S1 is an N-channel MOSFET, the source of which is connected to the negative terminal of the voltage source, and the drain of which is connected to the positive terminal of the voltage source; the first capacitor C1 is the sum of the parallel capacitor and the output capacitor of the first switch S1, and the first switch S1 functions as a free-wheeling when turned off; the second capacitor C2 is a resonant capacitor, the second inductor L2 is a resonant inductor, and the second capacitor C2 and the second inductor L2 together convert the high-frequency alternating current into a quasi-sine wave.

With continued reference to fig. 2, it may be understood that the second inductor L2 is a shared element of the class E inverter module 120 and the first filter module 130, and the first filter module 130 further includes a third capacitor C3, the other end of the second inductor L2 is electrically connected to one end of the dynamic capacitance compensation module 140 and one end of the third capacitor C3, respectively, and the other end of the third capacitor C3 is electrically connected to the negative terminal of the dc voltage input module 110. Specifically, the second inductor L2 is a filter inductor, the third capacitor C3 is a filter capacitor, and the second inductor L2 and the third capacitor C3 form a low-pass filter to filter out high-frequency interference.

The second inductor L2 functions as both a resonant inductor and a filter inductor, and functions to convert a high-frequency ac power into a quasi-sinusoidal wave and to filter the high-frequency ac power.

With continued reference to fig. 2, it may be understood that the capacitance dynamic compensation module 140 includes a first compensation branch and a second compensation branch, the first compensation branch includes a first switch component St1 and a fourth capacitor C4, the second compensation branch includes a second switch component St2 and a fifth capacitor C5, one end of the first switch component St1 and one end of the second switch component St2 are both electrically connected to the first filtering module 130, the other end of the first switch component St1 is electrically connected to one end of the fourth capacitor C4, the other end of the second switch component St2 is electrically connected to one end of the fifth capacitor C5, and the other end of the fourth capacitor C4 and the other end of the fifth capacitor C5 are both connected to the transmitting coil module 150. The first switch module St1 and the second switch module St2 are parallel selection switches respectively composed of two back-to-back MOSFETs, that is, the sources of the two MOSFETs are connected, or more switches and compensation capacitors may be connected in parallel according to the situation, and switching is performed according to different coupling situations between the transmitting coil module 150 and the receiving coil module 210, so as to improve the output capability; the fourth capacitor C4 and the fifth capacitor C5 are compensation capacitors, so as to compensate the inductive reactance of the transmitting coil module 150, thereby improving the output capability.

It can be understood that the capacitance dynamic compensation module 140 further includes at least one third compensation branch, and two ends of the third compensation branch are electrically connected to the first filtering module 130 and the transmitting coil module 150, respectively. At least one third compensation branch is further provided, so that the compensation capacitor can be selected more flexibly and in a wider range, the inductive reactance of the transmitting coil module 150 is compensated, and the output capability is improved.

With continued reference to fig. 2, it may be appreciated that the transmitting coil module 150 includes a third inductor L3 and a sixth capacitor C6, one end of each of the third inductor L3 and the sixth capacitor C6 is electrically connected to the first filtering module 130, and the other end of each of the third inductor L3 and the sixth capacitor C6 is electrically connected to the negative terminal of the dc voltage input module 110. The third inductor L3 and the sixth capacitor C6 are the self-inductance and the parasitic capacitance of the transmitting coil, respectively.

With continued reference to fig. 2, it can be understood that the receiving coil module 210 includes a fourth inductor L4 and a seventh capacitor C7, and two ends of the fourth inductor L4 and the seventh capacitor C7 are electrically connected to two input ends of the rectifying and filtering module 220, respectively. The fourth inductor L4 and the seventh capacitor C7 are the self-inductance and the parasitic capacitance of the receiving coil, respectively.

With continued reference to fig. 2, it is understood that the receiving coil module 210 further includes an eighth capacitor C8, one end of the eighth capacitor C8 is electrically connected to the fourth inductor L4 and the seventh capacitor C7, and the other end of the eighth capacitor C8 is electrically connected to one input end of the rectifying and filtering module 220. The eighth capacitor C8 is a series compensation capacitor for compensating the inductive reactance of the receiving coil module, specifically, for supplementing the inductive reactance of the fourth inductor L4, thereby improving the output capability.

It should be noted that the rectifying and filtering module 220 is composed of four diodes D1, D2, D3 and D4, and includes two input terminals and two output terminals, and is capable of converting alternating current into pulsating direct current.

With continued reference to fig. 2, it may be understood that the wireless power transmission system provided by the present application further includes a ninth capacitor C9, one end of the ninth capacitor C9 is electrically connected to one output terminal of the rectifying and filtering module 220 and one end of the load 230, and the other end of the ninth capacitor C9 is electrically connected to the other output terminal of the rectifying and filtering module 220 and the other end of the load 230. The ninth capacitor C9 is an output filter capacitor, and can convert the pulsating dc power into dc power, so as to transmit the electric energy to the load 230.

The wireless power transmission system of the present application is further described with a specific embodiment as follows:

referring to fig. 2, the system input is a dc voltage Vin capable of adjusting the amplitude according to the demand of the load 230, and then the dc voltage Vin is converted into a high-frequency quasi-sinusoidal wave through an E-class inverter module 120 composed of L1, S1, C1, C2, and L2; the sine wave passes through an LC first filtering module 130 consisting of a part L2 and a part C3, then high-frequency noise is filtered, and the high-frequency noise is sent to a capacitance dynamic compensation module 140, and a corresponding capacitor is selected to be switched on according to an actual load 230 and a coupling condition so as to compensate a transmitting coil consisting of L3 and C6 and mutual inductance M; the transmitting coil module 150 converts the electric energy into magnetic field energy, and the magnetic field energy is received by a receiving coil module 210 consisting of L4 and C7 and then converted into high-frequency alternating current electric energy; the energy is compensated by a capacitor C8, and then converted into direct current through a rectifying and filtering network consisting of D1-D4 and C9 to be supplied to a load 230 Rload.

In a second aspect, referring to fig. 3, the present application further provides a wireless charging system for a wearable device, including: a wireless power transfer system as in any one of the embodiments of the first aspect; the electronic device comprises a first driving and communication module 310, a first main control chip 320, a second communication module 410 and a second main control chip 420, wherein the first driving and communication module 310 is electrically connected with the class-E inverter module 120 and the transmitting coil module 150 respectively; the first main control chip 320 is electrically connected to the first driving and communication module 310, the dc voltage input module 110, and the dynamic capacitance compensation module 140, respectively; the second communication module 410 is electrically connected with the receiving coil module 210 and the rectifying and filtering module 220 respectively; the second main control chip 420 is electrically connected to the second communication module 410 and the load 230, respectively.

The specific working process comprises the following steps: after the transmitting terminal module 100, namely the wireless charger, is connected to a power supply for power supply, the wireless charging system starts self-checking; after the self-checking is passed, the first main control chip 320 sets an initial voltage for the dc voltage input module 110, and turns on the dynamic capacitance compensation module 140 to set an initial compensation capacitance; the first main control chip 320 sends a command to the first driving and communication module 310, so that the module outputs a fixed-frequency PWM wave at intervals to drive the first switch, and the system enters a standby state; after the wearable device is placed on the charger, that is, after the receiving end module 200 is connected to the load, the second main control chip 420 collects information such as device ID and battery voltage and stores the information in the second communication module 410; the first driving and communication module 310 detects the presence of a device through in-band communication, and then reads the device information in the second communication module 410 and sends the device information to the first main control chip 320; the first main control chip 320 completes system configuration according to the information and starts energy transmission; the first main control chip 320 selects appropriate capacitance compensation of the dc voltage input module 110 voltage and the capacitance dynamic compensation module 140 according to the information such as the output voltage requirement, and performs power adjustment; the second main control chip 420 continuously updates information such as output voltage and battery power and stores the information in the second communication module 410; the first driving and communication module 310 reads the relevant information such as the output voltage of the receiving end at intervals and sends the information to the first main control chip 320; repeating the above charging detection steps until the charging is finished or equipment failure occurs, and the first main control chip 320 makes a judgment according to the received information and enters the standby state again. Through the wireless charging system, long-distance and high-efficiency energy transmission under the conditions of high frequency, wide load range and coupling change can be realized.

The embodiments of the present application have been described in detail with reference to the drawings, but the present application is not limited to the embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims (10)

1. A wireless power transfer system, comprising:

the system comprises a transmitting end module, a receiving end module and a transmitting terminal module, wherein the transmitting end module comprises a direct-current voltage input module, an E-type inverter module, a first filtering module, a capacitance dynamic compensation module and a transmitting coil module which are sequentially and electrically connected, and the capacitance dynamic compensation module is used for realizing capacitance compensation on the transmitting coil module;

the receiving end module comprises a receiving coil module, a rectifying and filtering module and a load which are sequentially and electrically connected, and the receiving coil module is electrically coupled with the transmitting coil module.

2. The wireless power transmission system according to claim 1, wherein the class-E inverter module comprises a first inductor, a first switch, a first capacitor, a second inductor, and a second capacitor, one end of the first inductor is electrically connected to the positive terminal of the dc voltage input module, the other end of the first inductor is electrically connected to one end of the first switch, one end of the first capacitor, and one end of the second capacitor, respectively, the other end of the first switch and the other end of the first capacitor are electrically connected to the negative terminal of the dc voltage input module, and the other end of the second capacitor is connected to one end of the second inductor.

3. The wireless power transmission system according to claim 2, wherein the second inductor is a common component of the class E inverter module and the first filter module, the first filter module further includes a third capacitor, another end of the second inductor is electrically connected to one end of the dynamic capacitance compensation module and another end of the third capacitor, respectively, and another end of the third capacitor is electrically connected to a negative end of the dc voltage input module.

4. The wireless power transmission system according to claim 1, wherein the capacitance dynamic compensation module includes a first compensation branch and a second compensation branch, the first compensation branch includes a first switch component and a fourth capacitor, the second compensation branch includes a second switch component and a fifth capacitor, one end of the first switch component and one end of the second switch component are both electrically connected to the first filtering module, the other end of the first switch component is electrically connected to one end of the fourth capacitor, the other end of the second switch component is electrically connected to one end of the fifth capacitor, and the other end of the fourth capacitor and the other end of the fifth capacitor are both connected to the transmitting coil module.

5. The wireless power transmission system according to claim 4, wherein the capacitance dynamic compensation module further comprises at least one third compensation branch, and two ends of the third compensation branch are electrically connected to the first filtering module and the transmitting coil module, respectively.

6. The wireless power transmission system according to claim 1, wherein the transmitting coil module comprises a third inductor and a sixth capacitor, one end of each of the third inductor and the sixth capacitor is electrically connected to the first filter module, and the other end of each of the third inductor and the sixth capacitor is electrically connected to the negative terminal of the dc voltage input module.

7. The wireless power transmission system according to claim 1, wherein the receiving coil module comprises a fourth inductor and a seventh capacitor, and two ends of the fourth inductor and two ends of the seventh capacitor are electrically connected to two input ends of the rectifying and filtering module, respectively.

8. The wireless power transmission system according to claim 7, wherein the receiving coil module further comprises an eighth capacitor, one end of the eighth capacitor is electrically connected to the fourth inductor and the seventh capacitor, and the other end of the eighth capacitor is electrically connected to one input end of the rectifying and filtering module.

9. The wireless power transmission system according to claim 1, further comprising a ninth capacitor, wherein one end of the ninth capacitor is electrically connected to one output end of the rectifying and filtering module and one end of the load, and the other end of the ninth capacitor is electrically connected to the other output end of the rectifying and filtering module and the other end of the load.

10. A wireless charging system of wearable equipment, comprising:

a wireless power transfer system as claimed in any one of claims 1 to 9;

the first driving and communication module is electrically connected with the class-E inverter module and the transmitting coil module respectively;

the first master control chip is respectively and electrically connected with the first driving and communication module, the direct-current voltage input module and the capacitance dynamic compensation module;

the second communication module is electrically connected with the receiving coil module and the rectification filtering module respectively;

and the second main control chip is respectively and electrically connected with the second communication module and the load.

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