CN110789370B

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Info

Publication number: CN110789370B
Application number: CN201911025765.XA
Authority: CN
Inventors: 杨福源; 石秉坤; 欧阳明高; 刘玮; 胡超; 罗勇
Original assignee: Zhongxing New Energy Automobile Co ltd; Tsinghua University
Current assignee: Zhongxing New Energy Automobile Co ltd; Tsinghua University
Priority date: 2019-10-25
Filing date: 2019-10-25
Publication date: 2021-01-22
Anticipated expiration: 2039-10-25
Also published as: CN110789370A

Abstract

Translated fromChinese

本申请涉及一种无线充电系统中参数补偿方法及无线充电系统。上述无线充电系统，包括发射电路和与所述发射电路无线连接的接收电路。所述接收电路包括接收线圈、第一补偿电路以及第二补偿电路。所述接收线圈、所述第一补偿电路以及所述第二补偿电路依次电连接后，所述接收线圈的一端与所述发射电路无线连接。通过所述第二补偿电路可以改善无线充电系统的导纳增益曲线，减小所述接收电路中的接收电流的间谐波频率的幅值，进而提高所述无线充电系统的稳定性。

The present application relates to a parameter compensation method in a wireless charging system and a wireless charging system. The above wireless charging system includes a transmitter circuit and a receiver circuit wirelessly connected to the transmitter circuit. The receiving circuit includes a receiving coil, a first compensation circuit and a second compensation circuit. After the receiving coil, the first compensation circuit and the second compensation circuit are electrically connected in sequence, one end of the receiving coil is wirelessly connected to the transmitting circuit. Through the second compensation circuit, the admittance gain curve of the wireless charging system can be improved, the amplitude of the interharmonic frequency of the received current in the receiving circuit can be reduced, and the stability of the wireless charging system can be improved.

Description

Parameter compensation method in wireless charging system and wireless charging system

Technical Field

The present disclosure relates to the field of wireless power transmission technologies, and in particular, to a parameter compensation method in a wireless charging system and a wireless charging system.

Background

The application of wireless charging technology in the field of electric vehicles has become increasingly popular, and in engineering application: 1) the position between the ground equipment and the vehicle-mounted equipment is in an undetermined state along with the parking state, and the state of an automobile chassis along with the loading state in the vehicle also changes within a certain range, so that the horizontal offset distance and the vertical distance (ground clearance) between the primary coil and the secondary coil of the wireless charging system change within a certain range; 2) in the whole process of charging the automobile, the requirement on the charging voltage/current is dynamically changed, so that the wireless charging system needs to respond and meet the charging requirement of the automobile.

The secondary side controllable rectification scheme can better solve the engineering application problem, but the input current of the traditional controllable rectifier bridge has a certain oscillation problem. This oscillation not only subjects the device to higher current or voltage stresses, but also affects the stability and efficiency of the system.

Disclosure of Invention

Therefore, it is necessary to provide a parameter compensation method in a wireless charging system and a wireless charging system for solving the problem of current oscillation in vehicle-side control in the conventional wireless charging system.

A method of parameter compensation in a wireless charging system, the wireless charging system including a transmit circuit and a receive circuit wirelessly connected to the transmit circuit, the method comprising:

s10, estimating a frequency range of the input signal of the receiving circuit;

s20, performing impedance analysis on the wireless charging system, acquiring an admittance gain characteristic curve in the frequency range, and acquiring a reference high-gain point from the admittance gain characteristic curve so as to acquire a reference harmonic gain;

s30, providing a second compensation circuit model, connecting the second compensation circuit model with the receiving circuit, and adjusting the electrical parameters of the second compensation circuit model for N times, wherein N is a positive integer greater than or equal to 1;

s40, performing impedance analysis on the wireless charging system again under the electrical parameters of each second compensation circuit model to obtain N harmonic gains;

and S50, selecting a value smaller than the reference harmonic gain from the N harmonic gains as a target harmonic gain, obtaining a second compensation circuit according to the electrical parameter of the second compensation circuit model corresponding to the target harmonic gain, and performing parameter compensation on the receiving circuit.

In one embodiment, in S50, a value smaller than the reference harmonic gain is selected from the N harmonic gains to be a target harmonic gain, and a second compensation circuit is obtained according to an electrical parameter of the second compensation circuit model corresponding to the target harmonic gain, where the step of performing parameter compensation on the receiving circuit includes:

selecting a minimum value from the target harmonic gain, wherein the electrical parameter corresponding to the minimum value is an optimal parameter of the second compensation circuit model;

and according to the optimal parameters, a second compensation circuit is obtained, and parameter compensation is carried out on the receiving circuit.

In one embodiment, the step of estimating the frequency range of the input signal of the receiving circuit at S10 includes:

and estimating the frequency range of the input signal of the receiving circuit according to the sampling error and the control error of the input signal of the receiving circuit or according to an empirical value.

In one embodiment, the step S30 of providing a second compensation circuit model, connecting the second compensation circuit model to the receiving circuit, and adjusting an electrical parameter of the second compensation circuit model N times, where N is a positive integer greater than or equal to 1 includes:

and providing a second compensation circuit model, connecting the second compensation circuit model with the receiving circuit, and adjusting the capacitance parameter and the inductance parameter or the capacitance parameter and the inductance parameter of the second compensation circuit model for N times.

s100, when the wireless charging system oscillates, carrying out Fourier analysis on an input signal of the receiving circuit to obtain a reference oscillation amplitude of an inter-harmonic frequency component, and further obtain reference inter-harmonic oscillation;

s200, providing a second compensation circuit model, connecting the second compensation circuit model with the receiving circuit, and adjusting the electrical parameters of the second compensation circuit model for N times, wherein N is a positive integer greater than or equal to 1;

s300, under the electrical parameters of each second compensation circuit model, performing Fourier analysis on the input signal again to obtain N inter-harmonic oscillations;

s400, selecting a value smaller than the reference inter-harmonic oscillation from the N inter-harmonic oscillations as a target inter-harmonic oscillation, obtaining a second compensation circuit according to an electrical parameter of the second compensation circuit model corresponding to the target inter-harmonic oscillation, and performing parameter compensation on the receiving circuit.

In one embodiment, in S100, when the wireless charging system oscillates, the step of performing fourier analysis on the input signal of the receiving circuit to obtain a reference oscillation amplitude of the inter-harmonic frequency component, and further obtaining a reference inter-harmonic oscillation includes:

acquiring the waveform of the input signal;

and judging whether the wireless charging system oscillates or not according to the waveform form.

In one embodiment, in S400, a value smaller than the reference inter-harmonic oscillation is selected from the N inter-harmonic oscillations to be used as a target inter-harmonic oscillation, a second compensation circuit is obtained according to an electrical parameter of the second compensation circuit model corresponding to the target inter-harmonic oscillation, and the step of performing parameter compensation on the receiving circuit includes:

selecting a minimum value from the target inter-harmonic oscillation, wherein the electrical parameter corresponding to the minimum value is an optimal parameter of the second compensation circuit model;

In one embodiment, the step S300 of performing fourier analysis again on the input signal to obtain N inter-harmonic oscillations under the electrical parameter of each of the second compensation circuit models includes:

after the capacitance parameter and the inductance parameter or the capacitance parameter and the inductance parameter of the second compensation circuit model are adjusted each time, Fourier analysis is carried out on the input current signal of the receiving circuit to obtain inter-harmonic oscillation.

A wireless charging system, comprising:

a transmitting circuit; and

a receiving circuit wirelessly connected with the transmitting circuit;

the receiving circuit includes:

one end of the receiving coil is wirelessly connected with the transmitting circuit;

a first compensation circuit, one end of which is electrically connected to the other end of the receiving coil); and

and one end of the second compensation circuit is electrically connected with the other end of the first compensation circuit.

In one embodiment, the second compensation circuit includes:

and one end of the compensation capacitor is electrically connected with the other end of the first compensation circuit.

In one embodiment, the second compensation circuit includes:

and one end of the compensation inductor is electrically connected with the other end of the first compensation circuit.

In one embodiment, the second compensation circuit includes:

a compensation capacitor;

and the compensation inductor is electrically connected to the other end of the first compensation circuit after being connected with the compensation capacitor in series.

The wireless charging system comprises a transmitting circuit and a receiving circuit which is wirelessly connected with the transmitting circuit. The receiving circuit comprises a receiving coil, a first compensation circuit and a second compensation circuit. After the receiving coil, the first compensation circuit and the second compensation circuit are electrically connected in sequence, one end of the receiving coil is wirelessly connected with the transmitting circuit. The admittance gain curve of the wireless charging system can be improved through the second compensation circuit, the amplitude of inter-harmonic frequency of receiving current in the receiving circuit is reduced, and the stability of the wireless charging system is further improved.

Drawings

Fig. 1 is a flowchart of a parameter compensation method in a wireless charging system according to an embodiment of the present disclosure;

fig. 2 is a schematic equivalent circuit diagram of a wireless charging system according to an embodiment of the present application;

fig. 3 is a simplified diagram of a wireless charging system according to an embodiment of the present application;

fig. 4 is a graph illustrating improved front admittance gain of a wireless charging system according to an embodiment of the present application;

fig. 5 is a simplified diagram of a wireless charging system according to an embodiment of the present application;

fig. 6 is an admittance gain diagram of a wireless charging system according to an embodiment of the present application after improvement;

fig. 7 is a flowchart of a parameter compensation method in a wireless charging system according to an embodiment of the present disclosure;

fig. 8 is a block diagram of a wireless charging system according to an embodiment of the present application;

fig. 9 is a block diagram of a wireless charging system according to an embodiment of the present application;

fig. 10 is a block diagram of a wireless charging system according to an embodiment of the present application;

fig. 11 is a block diagram of a wireless charging system according to an embodiment of the present application.

Description of the main element reference numerals

Wireless charging system 10

Transmittingcircuit 100

Receivingcircuit 200

Receivingcoil 210

First compensation circuit 220

Second compensation circuit 230

Compensation capacitor 231

Compensation inductor 232

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the embodiments disclosed below.

It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, the present application provides a parameter compensation method in a wireless charging system. Thewireless charging system 10 includes a transmittingcircuit 100 and a receivingcircuit 200 wirelessly connected to the transmittingcircuit 100. The method comprises the following steps:

s10, estimating the frequency range of the input signal of the receivingcircuit 200. In step S10, the frequency range of the input signal of the receivingcircuit 200 is estimated based on the sampling error of the input signal of the receivingcircuit 200 or based on an empirical value. For example, when the operating frequency of the transmittingcircuit 100 is f₀Then the frequency range of the input signal of the receivingcircuit 200 is f₀±Δf。

S20, performing impedance analysis on thewireless charging system 10, obtaining an admittance gain characteristic curve in the frequency range, and obtaining a reference high gain point from the admittance gain characteristic curve, so as to obtain a reference harmonic gain. In step S20, the transmission of the transmittingcircuit 100 may be estimatedThe self-inductance of the radiation coil, the self-inductance of the receivingcoil 210 and the mutual inductance between the two, thereby constructing an equivalent circuit. Then, an admittance gain characteristic curve is obtained according to the circuit principle. And reading the admittance gain characteristic curve, acquiring a point with a higher gain amplitude value, and setting the point as a reference high gain point. At this time, the input current of the receivingcircuit 200 can be considered as the fundamental frequency f₀The component and the inter-harmonic frequency component corresponding to the reference high gain point are superposed. The number of the reference high gain points may be plural. The reference harmonic gain may be calculated in a variety of ways. For example, when the number of the reference high-gain points is two, the amplitudes of the two reference high-gain points may be summed, and then the sum is subjected to a quotient with the amplitude corresponding to the operating frequency in the admittance gain characteristic curve, so as to obtain the reference harmonic gain.

S30, providing a second compensation circuit model, connecting the second compensation circuit model to the receivingcircuit 200, and adjusting an electrical parameter of the second compensation circuit model N times, where N is a positive integer greater than or equal to 1. In step S30, the second compensation circuit model may include at least one of a capacitor and an inductor. When the second compensation circuit model only includes capacitance or only includes inductance, the capacitance parameter or the inductance parameter of the second compensation circuit model may be adjusted N times. When the second compensation circuit model includes both the capacitance parameter and the inductance parameter, the capacitance parameter or the inductance parameter needs to be adjusted N times at the same time.

S40, performing impedance analysis on thewireless charging system 10 again under the electrical parameters of each second compensation circuit model to obtain N harmonic gains. In step S40, N admittance gain characteristic curves under N sets of different electrical parameters may be obtained. A corresponding number of high gain points are obtained from each admittance gain characteristic curve, and a harmonic gain is obtained in the same manner as in step S20.

S50, selecting a value smaller than the reference harmonic gain from the N harmonic gains as a target harmonic gain, obtaining asecond compensation circuit 230 according to an electrical parameter of the second compensation circuit model corresponding to the target harmonic gain, and performing parameter compensation on the receivingcircuit 200. In step S50, the number of the target harmonic gains may be multiple, that is, multiple sets of electrical parameters may be present to perform parameter compensation on the receivingcircuit 200.

In this embodiment, thesecond compensation circuit 230 is obtained by comparing high gain points under various parameters. Thesecond compensation circuit 230 may reduce the magnitude of the gain point of thewireless charging system 10. When the number of gain points of thewireless charging system 10 is plural, the amplitude of each gain point may be reduced by thesecond compensation circuit 230. That is, the oscillation phenomenon of the input current of the receivingcircuit 200 can be greatly improved, and the stability of the system can be greatly improved.

In one embodiment, in S50, a value smaller than the reference harmonic gain is selected from the N harmonic gains to be a target harmonic gain, and thesecond compensation circuit 230 is obtained according to the electrical parameter of the second compensation circuit model corresponding to the target harmonic gain, where the step of performing parameter compensation on the receivingcircuit 200 includes:

and selecting a minimum value from the target harmonic gain, wherein the electrical parameter corresponding to the minimum value is the optimal parameter of the second compensation circuit model. According to the optimal parameters, asecond compensation circuit 230 is obtained to perform parameter compensation on the receivingcircuit 200. At this time, the obtainedsecond compensation circuit 230 is the optimal compensation parameter under the current working condition.

Fig. 2 is a schematic diagram of an equivalent circuit of a wireless charging system obtained by performing impedance analysis on a conventional wireless charging system. In the above diagram, Rin ═ Vin/Iin, where Vin and Iin are the voltage and current at the illustrated positions, and are complex variables, and the division is a complex division. Rin _ im is the imaginary part of Rin, and Rin _ re is the real part of Rin; l1, C1, Cp, L2, C2, Cs are inductive or capacitive elements in a conventional wireless charging system; lp, Ls, M are the transmit coil self-inductance, the receive coil self-inductance, and the mutual inductance of the two, respectively.

Ze is the equivalent impedance of the circuit on the left side of the inductor L2 in fig. 2. The computing method of the Ze is just to calculate the series-parallel connection rule according to the circuit principle. A simplified diagram of the wireless charging system shown in fig. 3 is obtained. As can be seen from fig. 3:

where ω is an angular frequency, ω is 2 pi f, and f satisfies the frequency range of the input signal of the receivingcircuit 200 in S10.

Assuming that the controllable rectifier bridge operating frequency f0 of the receivingcircuit 200 is 85kHz, and the possible frequency range is 50kHz to 120kHz, the frequency characteristic of admittance under a certain set of parameters is shown in fig. 4. As can be seen from fig. 4, the admittance gains of the system are particularly large at around 58kHz and around 105kHz at this time, which means that even a small component of the frequency in Ve will result in a large current component at that frequency. The Ie current at this time can be considered to be composed of a fundamental frequency f0 component and a frequency component of two inter-harmonic waves of 58KHz and 105KHz, which causes oscillation of the Ie current and instability of the system. At this time, the reference harmonic gain may be obtained by the following equation (2):

wherein f is₀To the operating frequency, f₁，f₂Corresponding to two target high gain points.

The reference harmonic gain can also be obtained by the following equation (3):

when the series inductance Lc2 and the series capacitance Cc2 are added, the parameters of the series inductance Lc2 and the series capacitance Cc2 are adjusted, and the admittance gain curve is improved. The schematic diagram of the system after adding the series inductance Lc2 and the series capacitance Cc2 is shown in fig. 5. The improved admittance gain curve is shown in fig. 6 by adjusting the parameters of the series inductance Lc2 and theseries capacitance Cc 2. As can be seen from fig. 6, in the frequency range, the admittance gain is well suppressed, and at this time, the Ie current only includes the amplitude of a small other frequency component, so that the phenomenon of Ie current oscillation can be greatly improved, and the system stability is greatly improved.

Referring to fig. 7, the present application provides a parameter compensation method in a wireless charging system. Thewireless charging system 10 includes a transmittingcircuit 100 and a receivingcircuit 200 wirelessly connected to the transmittingcircuit 100. The method comprises the following steps:

s100, when thewireless charging system 10 oscillates, performing fourier analysis on the input signal of the receivingcircuit 200 to obtain a reference oscillation amplitude of the inter-harmonic frequency component, so as to obtain reference inter-harmonic oscillation. In step S100, the number of reference oscillation amplitudes may be plural. The reference inter-harmonic oscillation may be calculated in a variety of ways. For example, when the number of the reference oscillation amplitudes is two, the two reference oscillation amplitudes may be summed, and then the sum is given as a quotient with the amplitude corresponding to the operating frequency, so as to obtain the reference inter-harmonic oscillation. The reference inter-harmonic oscillation is calculated in a similar manner to the reference harmonic gain. And will not be described in detail herein.

In order to realize the normal charging function of thewireless charging system 10, it is necessary to satisfy: 1) the operating frequency of the receivingcircuit 200 is the same as the operating frequency of the transmittingcircuit 100; 2) the phase between the input voltage Ve and the input current Ie of the receivingcircuit 200 is stable.

The common control method is to sample the Ie current, extract frequency and phase information of the Ie current (mainly realized by collecting the Ie current zero-crossing information), and generate a control signal of the MOS transistor according to the frequency and the phase information (the Ie current frequency is used as the operating frequency of the MOS transistor, and the Ie phase information is used as the reference to control the switching phase of the MOS transistor). Under the control mode, due to the influence of relevant factors such as sampling precision, switching control precision and inter-harmonics, a certain distortion or error exists in the zero crossing of the Ie current, so that errors in a certain range exist in the frequency and the phase of the Ie current. If there is a higher gain point in the frequency range for the system admittance at this time, it may further cause the oscillation of the Ie current, affecting the stability of the system. Fourier decomposition of this Ie current signal was carried out and the presence of larger inter-harmonics was observed. Therefore, it can be determined whether thewireless charging system 10 oscillates according to the voltage waveform of the Ie current or the Ve current in thewireless charging system 10.

S200, providing a second compensation circuit model, connecting the second compensation circuit model with the receivingcircuit 200, and adjusting the electrical parameters of the second compensation circuit model for N times, wherein N is a positive integer greater than or equal to 1. In step S200, the second compensation circuit model may include at least one of a capacitor and an inductor. When the second compensation circuit model only includes capacitance or only includes inductance, the capacitance parameter or the inductance parameter of the second compensation circuit model may be adjusted N times. When the second compensation circuit model includes both the capacitance parameter and the inductance parameter, the capacitance parameter or the inductance parameter needs to be adjusted N times at the same time.

And S300, under the electrical parameters of each second compensation circuit model, performing Fourier analysis on the input signal again to obtain N inter-harmonic oscillations. In step S30, N sets of different electrical parameters and their corresponding oscillation amplitudes may be obtained, and a harmonic gain may be obtained by the same method as in step S100.

S400, selecting a value smaller than the reference inter-harmonic oscillation from the N inter-harmonic oscillations as a target inter-harmonic oscillation, obtaining asecond compensation circuit 230 according to an electrical parameter of the second compensation circuit model corresponding to the target inter-harmonic oscillation, and performing parameter compensation on the receivingcircuit 200. In step S400, the number of the target inter-harmonic oscillations may be multiple, that is, multiple sets of electrical parameters may be present, and the parameters of the receivingcircuit 200 may be compensated.

In this embodiment, thesecond compensation circuit 230 is obtained by comparing the amplitudes of the inter-harmonic frequency components under various parameters. Thesecond compensation circuit 230 may reduce the magnitude of the gain point of thewireless charging system 10. When the number of oscillation amplitudes of thewireless charging system 10 is plural, each oscillation amplitude may be reduced by thesecond compensation circuit 230. That is, the oscillation phenomenon of the input current of the receivingcircuit 200 can be greatly improved, and the stability of the system can be greatly improved.

In one embodiment, S400, selecting a value smaller than the reference inter-harmonic oscillation from the N inter-harmonic oscillations as a target inter-harmonic oscillation, and obtaining thesecond compensation circuit 230 according to an electrical parameter of the second compensation circuit model corresponding to the target inter-harmonic oscillation, so as to improve the stability of the wireless charging system, includes:

and selecting a minimum value from the target inter-harmonic oscillation, wherein the electrical parameter corresponding to the minimum value is the optimal parameter of the second compensation circuit model. According to the optimal parameters, asecond compensation circuit 230 is obtained to perform parameter compensation on the receivingcircuit 200. At this time, the obtainedsecond compensation circuit 230 is the optimal compensation parameter under the current working condition. In actual engineering, more working conditions need to be considered, and the electrical parameter selection of the second compensation circuit model needs to be comprehensively selected on the basis of the method.

Referring to fig. 8, the present application provides awireless charging system 10. Thewireless charging system 10 includes a transmittingcircuit 100 and a receivingcircuit 200 wirelessly connected to the transmittingcircuit 100.

The transmittingcircuit 100 may include an inverter, a third compensating circuit, and a transmitting coil. The inverter may be a full bridge inverter formed by four inverting power switches. The inverter may be operated at a switching frequency f₀The direct current is converted into high-frequency alternating current. The third compensation circuit is electrically connected with the inverter and used for absorbing reactive energy. The third compensation circuit may be an LCC compensation circuit. The transmitting coil is used for converting high-frequency alternating current into magnetic energy.

The receivingcircuit 200 includes a receivingcoil 210, a first compensatingcircuit 220, and a second compensatingcircuit 230. One end of the receivingcoil 210 is connected to the transmitting coil of the transmittingcircuit 100 in a mutual inductance manner. One end of thefirst compensation circuit 220 is electrically connected to the other end of the receivingcoil 210. One end of thesecond compensation circuit 230 is electrically connected to the other end of thefirst compensation circuit 220. The receivingcoil 210 is used to convert magnetic energy into electric energy. Thefirst compensation circuit 220 is used to absorb reactive energy. Thesecond compensation circuit 230 is used to prevent the oscillation of current and voltage, and ensure the stability of the system.

Thewireless charging system 10 includes a transmittingcircuit 100 and a receivingcircuit 200 wirelessly connected to the transmittingcircuit 100. The receivingcircuit 200 includes a receivingcoil 210, a first compensatingcircuit 220, and a second compensatingcircuit 230. After the receivingcoil 210, the first compensatingcircuit 220 and the second compensatingcircuit 230 are electrically connected in sequence, one end of the receivingcoil 210 is wirelessly connected to the transmittingcircuit 100. The admittance gain curve of the wireless charging system can be improved by thesecond compensation circuit 230, and the amplitude of the inter-harmonic frequency of the receiving current in the receivingcircuit 200 is reduced, thereby improving the stability of thewireless charging system 10.

Referring to fig. 9, in an alternative embodiment, thesecond compensation circuit 230 includes acompensation capacitor 231. One end of thecompensation capacitor 231 is electrically connected to the other end of thefirst compensation circuit 220. The inductance value of thefirst compensation circuit 220 may be a larger inductance value. The admittance gain curve of the wireless charging system can be improved by thecompensation capacitor 231, and the amplitude of the inter-harmonic frequency of the receiving current in the receivingcircuit 200 is reduced, thereby improving the stability of thewireless charging system 10.

Referring to fig. 10, in an alternative embodiment, thesecond compensation circuit 230 includes acompensation inductor 232. One end of thecompensation inductor 232 is electrically connected to the other end of thefirst compensation circuit 220. The admittance gain curve of the wireless charging system can be improved by thecompensation inductor 232, and the amplitude of the inter-harmonic frequency of the receiving current in the receivingcircuit 200 is reduced, thereby improving the stability of thewireless charging system 10.

Referring to fig. 11, in an alternative embodiment, thesecond compensation circuit 230 includes acompensation capacitor 231 and acompensation inductor 232. Thecompensation inductor 232 is electrically connected to the other end of thefirst compensation circuit 220 after being connected in series with thecompensation capacitor 231. The admittance gain curve of the wireless charging system can be improved by thecompensation capacitor 231 and thecompensation inductor 232, and the amplitude of the inter-harmonic frequency of the receiving current in the receivingcircuit 200 is reduced, thereby improving the stability of thewireless charging system 10.

In an alternative embodiment, the receivingcircuit 200 further comprises a rectifier filter. The rectifier filter is electrically connected to thesecond compensation circuit 230. The rectifier filter may be a fully controlled rectifier filter. The rectifier filter may be a half-controlled rectifier filter.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.