Fast self-adaptive impedance matching method and system and wireless power transmission system

Abstract

The invention discloses a fast self-adaptive impedance matching method and system and a wireless power transmission system, an MCU enables a pi-type impedance matching network to be in a short circuit state by controlling a relay switch, two groups of reflection coefficients of the system are obtained through measurement of an amplitude phase measurement circuit, and two groups of input impedance are calculated; and calculating to obtain a theoretical optimal capacitor combination corresponding to each input impedance. And actually measuring the reflection coefficients of the two input impedances in the corresponding theoretical optimal capacitor combination, wherein the capacitor combination with the smaller reflection coefficient is the actual optimal capacitor combination. Furthermore, according to the method, a local optimal solution is searched around an actual optimal capacitor combination, and re-impedance matching is completed. And dynamically monitoring the input impedance of the system under the given frequency, and repeating the steps when the change of the input impedance exceeds a set threshold value. According to the method, theoretical calculation is combined with hardware testing, the matching efficiency of the system is greatly improved, in addition, the influence of parasitic parameters on the matching precision of the system can be effectively avoided through a local optimization control algorithm, the transmission efficiency and stability of the system are further improved, and good practicability is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of impedance matching for wireless power transmission, and in particular relates to a fast adaptive impedance matching method, system and wireless power transmission system. Background Art

[0002] Wireless power transfer (WPT) technology has attracted widespread attention in the fields of medical equipment, electric vehicle charging, household appliances, medical electronics, and the Internet of Things due to its safety, convenience, and high efficiency. In the actual application of wireless power transmission systems, when the transmission distance of the system changes or the surrounding environment of the transmitting (or receiving) end changes, the input impedance of the system may change, thereby causing impedance mismatch problems, which greatly affects the transmission efficiency and power stability of the wireless power transmission system. Therefore, in the design of wireless power transmission systems, matching issues have always occupied a vital position. For example, when using wireless charging technology to charge a mobile phone, once the mobile phone deviates from the charging plate, the transmission efficiency will drop rapidly. Similar problems also exist in the wireless charging system of electric vehicles. Existing charging systems have strict regulations on the alignment of coils and transmission distances.

[0003] However, existing technologies have shown many limitations in dealing with this key issue. First, in different working scenarios and environmental conditions, adaptive matching is usually required quickly, and current technologies can hardly meet the needs of dynamic changes. Secondly, the level of system automation is insufficient, and matching work often still relies on manual intervention. This is not only inefficient, but also prone to human errors. Furthermore, the matching system has poor accuracy, and it is difficult to achieve accurate matching in practice, which affects the transmission effect. In addition, low matching efficiency seriously hinders the efficient operation of the circuit and has become one of the main obstacles to the application of wireless power transmission systems. Summary of the invention

[0004] The object of the present invention is to provide a fast adaptive impedance matching method, system and wireless power transmission system, aiming to solve the above-mentioned problems.

[0005] The present invention is mainly achieved through the following technical solutions:

[0006] A fast adaptive impedance matching method realizes adaptive impedance matching of a system by dynamically controlling the impedance value of a π-type impedance matching network through an MCU; the method comprises the following steps:

[0007] Step S1: The MCU controls the relay switch to put the π-type impedance matching network into a short-circuit state, and uses the amplitude phase measurement circuit to measure two sets of reflection coefficients of the system, one of which is a pseudo value, and the MCU calculates the two input impedances of the system accordingly;

[0008] Step S2: For the two input impedances, the MCU calculates the reflection coefficients corresponding to all capacitor combinations of the π-type impedance matching network, where the capacitor combination corresponding to the minimum reflection coefficient is the theoretical optimal capacitor combination corresponding to each input impedance; the reflection coefficients of the two input impedances at the corresponding theoretical optimal capacitor combination are measured using the amplitude phase measurement circuit, and the capacitor combination with the smaller reflection coefficient is the actual optimal capacitor combination (C l-opt1 , C l-opt2 );

[0009] Step S3: Find the optimal capacitance combination (C l-opt1 , C l-opt2 ) to perform a local search:

[0010] Γ n =f(C N +α*D m ) (4)

[0011] Where: n is the local minimum reflection coefficient after n iterations;

[0012] f is the local optimization iteration function;

[0013] C N is the best capacitor combination corresponding to the local optimal solution after N iterations;

[0014] α is the minimum step value;

[0015] D m is a position matrix and is represented as ([-1,-1],[-1,0],[-1,1],[0,-1],[0,0],[0,1],[1,-1],[1,0],[1,1]);

[0016] The case with the smallest reflection coefficient among the nine capacitor combinations can be determined by measurement, which represents the local optimal solution in this iteration. By following this method until the maximum number of iterations is reached, the actual optimal capacitor combination (C r-opt1 , C r-opt2 ), the MCU controls the π-type impedance matching network to complete the re-matching and enters step S4; if no new local optimal capacitor combination is found during the iteration process, C N As the actual optimal capacitor combination (C r-opt1 , C r-opt2 ) to match, and directly proceed to step S4;

[0017] Step S4: dynamically monitor the input impedance of the system at a given frequency using an amplitude and phase measurement circuit. When the input impedance changes beyond a set threshold, proceed to step S1.

[0018] In order to better implement the present invention, further, in step S1, the input impedance Z in The calculation formula is:

[0019]

[0020] Where: Z0 is the characteristic impedance;

[0021] Γ is the reflection coefficient.

[0022] In order to better implement the present invention, further, in step S1, the MCU realizes the input impedance Z by changing the capacitance of the adjustable capacitor C1 and the adjustable capacitor C2 in the π-type impedance matching network. in The system is adjusted to match the input impedance Z. in The calculation formula is:

[0023]

[0024] Where: Z L To match the input impedance when the load is short-circuited;

[0025] ω is the angular frequency of the system;

[0026] L is the series inductance in the π-type impedance matching network;

[0027] Two groups of theoretical optimal capacitance combinations are calculated using formula (2) and formula (3), and one group is a pseudo value.

[0028] The present invention is mainly achieved through the following technical solutions:

[0029] A fast adaptive impedance matching system is based on the above-mentioned fast adaptive impedance matching method, comprising a signal source, an amplitude phase measurement circuit, a π-type impedance matching network and an MCU, wherein the signal source is connected to the π-type impedance matching network through the amplitude phase measurement circuit, and the MCU is respectively connected to the amplitude phase measurement circuit and each relay switch of the π-type impedance matching network; the amplitude phase measurement circuit comprises a dual directional coupler, an attenuator and an AD8302 chip, wherein the input end and the through end of the dual directional coupler are respectively connected to the output end of the signal source and the input end of the π-type impedance matching network, and the coupling end and the isolation end of the dual directional coupler are respectively connected to the input port of the AD8302 chip through the attenuator; the amplitude and phase detection ends of the AD8302 chip are connected to the universal input port of the MCU.

[0030] In order to better implement the present invention, further, the signal source includes a signal generator and a power amplifier, and the signal transmitter is connected to the input end of the dual directional coupler through the power amplifier.

[0031] In order to better implement the present invention, further, the π-type impedance matching network includes a fixed value inductor L and an adjustable capacitor C1 and an adjustable capacitor C2. The left and right sides of the fixed value inductor L are respectively connected in parallel with the adjustable capacitor C1 and the adjustable capacitor C2. The adjustable capacitor C1 and the adjustable capacitor C2 are respectively composed of N capacitors C n-i In parallel, each capacitor C n-i (n=1,2, i=1,2, ...N) is connected to a relay switch, the relay switch is connected to the MCU, and the capacitor C n-i Equal to 2 of the minimum step capacitance value i-1 times.

[0032] The present invention is mainly achieved through the following technical solutions:

[0033] A wireless power transmission system comprises the above-mentioned fast adaptive impedance matching system, and also comprises a receiving end and a transmitting end, wherein the output end of the π-type impedance matching network is connected to the transmitting end.

[0034] In order to better implement the present invention, further, the receiving end includes a receiving coil, a resonant capacitor C r2 and load, the resonant capacitor C r2 The two sides of the receiving coil and the load are respectively arranged in series; the transmitting end is correspondingly provided with a transmitting coil and a resonant capacitor C r1 , the resonant capacitor C r1 A transmitting coil and a π-type impedance matching network are respectively arranged in series on both sides.

[0035] The beneficial effects of the present invention are as follows:

[0036] The present invention utilizes MCU and amplitude phase measurement circuit to dynamically monitor the matching state of the wireless power transmission system at a given frequency, and can automatically start the impedance matching program when the system is mismatched. The present invention can adaptively adjust the π-type impedance matching network according to the input impedance of the receiving end to achieve adaptive matching of the system. The present invention realizes autonomous detection of the matching state of the system, and can efficiently and accurately achieve re-matching of the system, greatly improving the matching efficiency and stability of the system. In addition, the local optimization control algorithm proposed in the present invention can effectively avoid the influence of parasitic parameters on the matching accuracy of the system, and further enhance the transmission efficiency and stability of the system.

[0037] In the wireless power transmission system designed by the present invention, when the input impedance of the wireless power transmission system changes, the system can achieve adaptive matching. The application uses the MCU and the amplitude phase measurement circuit to monitor the changes in the input impedance of the system in real time, and achieves adaptive matching by adjusting the π-type impedance matching network. Compared with the traditional pure hardware debugging method, the method based on theoretical calculation combined with hardware testing proposed by the present invention greatly improves the matching efficiency, enhances the transmission efficiency and power stability of the system, and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A principle block diagram of a wireless power transmission system of the present invention;

[0039] Figure 2 It is a circuit diagram based on a binary π-type impedance matching network;

[0040] Figure 3 A flowchart of a fast adaptive impedance matching method of the present invention;

[0041] Figure 4 This is a schematic structural diagram of an actual product of an inductive wireless power transmission system based on a PCB coil in Example 4;

[0042] Figure 5 This is a comparison chart of the change curves of the received power of the wireless power transmission system with the transmission distance in three matching situations in Example 4.

[0043] Among them: 1-MCU, 2-π-type impedance matching network, 3-signal source, 4-dual directional coupler, 5-attenuator, 6-AD8302 chip, 7-receiving coil, 8-transmitting coil, 9-load. DETAILED DESCRIPTION

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and therefore should not be regarded as limiting the scope of protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without making creative work are within the scope of protection of the present invention.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] Embodiment 1:

[0047] A fast adaptive impedance matching method uses MCU1 and amplitude phase measurement circuit to dynamically monitor the input impedance change of the system at a given frequency. When the system is mismatched, the impedance matching program can be automatically started. The π-type impedance matching network 2 is adaptively adjusted to achieve adaptive matching of the system. Specifically, the following steps are included:

[0048] (1) MCU1 controls the relay switch to put the π-type impedance matching network 2 in a short-circuit state, and uses the amplitude and phase measurement circuit to measure two sets of reflection coefficients of the system, one of which is a pseudo value. MCU1 calculates the two input impedances of the system accordingly;

[0049] (2) For the two input impedances, MCU1 calculates the reflection coefficients corresponding to all capacitor combinations of the π-type impedance matching network 2, where the capacitor combination corresponding to the minimum reflection coefficient is the theoretical optimal capacitor combination corresponding to each input impedance; the reflection coefficients of the two input impedances at the corresponding theoretical optimal capacitor combination are measured using the amplitude and phase measurement circuit, and the capacitor combination with the smaller reflection coefficient is the actual optimal capacitor combination (C l-opt1 , C l-opt2 );

[0050] (3) Due to the influence of circuit parasitic parameters and potential complex environmental factors around the coil, the theoretical optimal solution does not necessarily represent the optimal solution of the system. Therefore, the present invention proposes an optimization algorithm to search for a local optimal solution around the theoretical optimal solution, complete the re-impedance matching, and enter the next step.

[0051] (4) The input impedance of the system at a given frequency is dynamically monitored using an amplitude and phase measurement circuit. When the input impedance changes beyond a set threshold, step (1) is entered, and the entire algorithm forms a closed loop.

[0052] Preferably, if Figure 3 As shown, the specific steps include:

[0053] Step A1: MCU1 controls the relay switch to put the π-type impedance matching network 2 in a short-circuit state. The amplitude phase measurement circuit is used to measure two sets of reflection coefficients of the system, and one set is a pseudo value. This is because the single Vphs value of the AD8302 chip 6 corresponds to two phase differences. MCU1 uses formula (2) to calculate the two input impedances Z of the system in ;

[0054]

[0055] Where: Z0 is the characteristic impedance;

[0056] Γ is the reflection coefficient.

[0057] Step A2: As shown in formula (3), the input impedance of the system after connecting to the π-type impedance matching network 2 is:

[0058]

[0059] Where: Z L To match the input impedance when the load 9 is short-circuited;

[0060] ω is the angular frequency of the system;

[0061] L is the series inductance in the π-type impedance matching network 2;

[0062] For the two input impedances, MCU1 uses equation (3) to calculate the 2 2N The reflection coefficients corresponding to the capacitor combinations (C1, C2) are calculated, where the capacitor combination corresponding to the minimum reflection coefficient is the theoretical optimal capacitor combination corresponding to each input impedance; the reflection coefficients of the two input impedances at the corresponding theoretical optimal capacitor combination are measured using the amplitude and phase measurement circuit, and the capacitor combination with the smaller reflection coefficient is the actual optimal capacitor combination (C l-opt1 , C l-opt2 );

[0063] Step A3: Perform a local search around the actual optimal capacitor combination within the capacitance interval of the π-type impedance matching network 2:

[0064] Γ n =f(C N +α*D m ) (4)

[0065] Where: n is the local minimum reflection coefficient after n iterations;

[0066] f is the local optimization iteration function;

[0067] C N is the capacitor combination corresponding to the local optimal solution after N iterations;

[0068] α is the minimum step value;

[0069] D m is a position matrix and is represented as ([-1,-1],[-1,0],[-1,1],[0,-1],[0,0],[0,1],[1,-1],[1,0],[1,1]);

[0070] The case with the smallest reflection coefficient among the nine capacitor combinations can be determined by measurement, which represents the local optimal solution in this iteration. By following this method until the maximum number of iterations is reached, the actual optimal capacitor combination (C r-opt1 , C r-opt2 ), MCU1 controls the π-type impedance matching network 2 to complete the re-matching and enters step A4; if no new local optimal capacitor combination is found during the iteration process, C N As the actual optimal capacitor combination (C r-opt1 , C r-opt2 ) to match, and directly proceed to step A4;

[0071] Step A4: Use the amplitude phase measurement circuit to dynamically monitor the input impedance of the system at a given frequency. When the input impedance changes beyond a set threshold, proceed to step A1.

[0072] This method proposes a method based on theoretical calculation combined with hardware testing, which greatly improves the matching efficiency. In addition, the local optimization control algorithm proposed by this method can effectively avoid the influence of parasitic parameters on the matching accuracy of the wireless power transmission system, and further improve the transmission efficiency and stability of the wireless power transmission system.

[0073] Embodiment 2:

[0074] A fast adaptive impedance matching system is operated based on the method in Example 1, such as Figure 1 As shown, the system includes a signal source 3Vs, an amplitude phase measurement circuit, a π-type impedance matching network 2 and an MCU1. The signal source 3 is connected to the input end of the dual directional coupler 4 in the amplitude phase measurement circuit. The input end of the π-type impedance matching network 2 is connected to the through port of the dual directional coupler 4. The MCU1 is connected to the amplitude phase measurement circuit and each relay switch unit of the π-type impedance matching network 2. The signal source 3 includes a signal generator and a power amplifier. The fixed frequency signal generated by the signal transmitter is amplified by the amplifier and then connected to the input end of the dual directional coupler 4 in the amplitude phase measurement circuit.

[0075] The amplitude and phase measurement circuit is composed of a dual directional coupler 4, an attenuator 5, and a chip (AD8302 chip 6). The input end and the through end of the dual directional coupler 4 are respectively connected to the signal source 3 and the input end of the π-type impedance matching network 2. The signals at the coupling end and the isolation end are attenuated by the attenuator 5 and then connected to the input port of the AD8302 chip 6. The amplitude and phase detection signals of the AD8302 chip 6 are connected to the universal input port of the MCU1.

[0076] like Figure 2 As shown, the π-type impedance matching network 2 is composed of a fixed value inductor and two adjustable capacitors C1 and C2 connected in parallel to each other. The adjustable capacitors C1 and C2 are respectively composed of N capacitors C n-i (n=1,2,i=1,2,…N) are connected in parallel, each capacitor C n-i Connected to a relay switch, which is connected to MCU1. MCU1 controls the relay switch K n-i It can realize precise regulation of adjustable capacitors C1 and C2 within a given capacitance value range. n-i Equal to 2 of the minimum step capacitance value i-1 The capacitance value of capacitors C1 and C2 varies from 0 to (2 N -1)*Cs; where Cs is the minimum step capacitance value.

[0077] Embodiment 3:

[0078] A wireless power transmission system, such as Figure 1 As shown, the fast adaptive impedance matching system described in Example 2 also includes a transmitting end and a receiving end of a wireless power transmission system, and the output end of the π-type impedance matching network 2 is connected to the transmitting end. The transmitting end usually includes a resonant capacitor and a transmitting coil 8. The receiving end usually includes a receiving coil 7, a resonant capacitor and a load 9.

[0079] The signal source 3Vs is composed of a signal generator and a power amplifier. The fixed-frequency signal generated by the signal transmitter enters the transmitter after passing through the power amplifier, the dual directional coupler 4 and the π-type impedance matching network 2. Finally, it enters the load 9 in the receiving end through magnetic coupling, thereby realizing wireless power transmission. The transmission efficiency is equal to:

[0080]

[0081] Where: P L Indicates the power received by load 9; P in Represents the input power of the system.

[0082] The main factors that determine the transmission efficiency include the matching problem of the entire circuit and the transmission efficiency of the transmitter and the receiver. The latter is mainly determined by factors such as the quality factor and coupling coefficient of the receiving coil 7 / transmitting coil 8. The present invention mainly improves the overall transmission efficiency of the wireless power transmission system by improving the matching performance between the signal source 3 and the transmitter in the wireless power transmission system.

[0083] Working principle: Figure 1 As shown, the dual directional coupler 4 can couple the input wave from the signal source 3Vs and the reflected wave from the π-type impedance matching network 2 to the coupling end and the isolation end for output at a fixed ratio. The two signals pass through the attenuator 5 and enter the input end of the AD8302 chip 6. The output end (V mag and V phs ) is connected to the universal input interface of MCU1. MCU1 can calculate the amplitude ratio and phase difference of the incident wave and the reflected wave based on the two output signals of AD8302 chip 6, and then obtain the reflection coefficient Γ of the wireless power transmission system. Then, the input impedance Z of the wireless power transmission system can be obtained by using formula (2): in .

[0084] When the input impedance of the wireless power transmission system changes, the wireless power transmission system can achieve adaptive matching. The changes in the input impedance of the wireless power transmission system are monitored in real time by MCU1 and the amplitude phase measurement circuit, and the adaptive matching of the wireless power transmission system is achieved by adjusting the π-type impedance matching network 2. Compared with the traditional pure hardware debugging method, the method of combining theoretical calculation with hardware testing in the present invention greatly improves the matching efficiency of the wireless power transmission system. In addition, the local optimization control algorithm proposed in the present invention can effectively avoid the influence of parasitic parameters on the matching accuracy of the wireless power transmission system, and further improve the transmission efficiency and power stability of the wireless power transmission system.

[0085] Embodiment 4:

[0086] Based on Example 1 to Example 3, an inductive wireless power transmission system based on a PCB coil is constructed. Figure 4 As shown, the transmitting coil 8 and the receiving coil 7 have the same structural parameters. In order to reduce the measurement error caused by the position offset of the coil, the present invention uses a cylindrical guide rod made of polyethylene material to pass through the center of the coil. With this design, the transmission distance and input impedance of the system can be changed by sliding the receiving coil 7, so that the system is in a mismatched state.

[0087] like Figure 5As shown, when the transmission distance of the wireless power transmission system is changed, the changes in the received power of the load 9 under the three conditions of no matching network, matching network, and matching network combined with the optimization algorithm. Compared with the absence of a matching network, the decrease in the received power with distance in the other two cases is significantly reduced. At the same time, within the transmission distance range studied, the stability of the received power of the system with the matching load 9 is significantly improved. In particular, when using the local optimization algorithm, the oscillation amplitude of the system received power is reduced by 60.0%. It can be seen that the adaptive impedance matching scheme involved in the present invention has made significant progress.

[0088] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A fast adaptive impedance matching method, characterized in that: Dynamically controlling the impedance value of a π-type impedance matching network (2) by an MCU (1) to achieve adaptive impedance matching of the system; the method comprises the following steps: Step S1: MCU (1) controls the relay switch to put the π-type impedance matching network (2) into a short-circuit state, and uses the amplitude phase measurement circuit to measure two groups of reflection coefficients of the system, one of which is a pseudo value, and MCU (1) correspondingly calculates two input impedances of the system; Step S2: for the two input impedances, the MCU (1) calculates the reflection coefficients corresponding to all the capacitor combinations of the π-type impedance matching network (2), wherein the capacitor combination corresponding to the minimum reflection coefficient is the theoretical optimal capacitor combination corresponding to each input impedance; the reflection coefficients of the two input impedances at the corresponding theoretical optimal capacitor combination are measured using an amplitude phase measurement circuit, and the capacitor combination with the smaller reflection coefficient is the actual optimal capacitor combination (C l-opt1 , C l-opt2 ); Step S3: In the capacitance range of the π-type impedance matching network (2), the actual optimal capacitance combination (C l-opt1 , C l-opt2 ) to perform a local search: C n =f(C N +a*D m ) (4) Where: n is the local minimum reflection coefficient after n iterations; f is the local optimization iteration function; C N is the best capacitor combination corresponding to the local optimal solution after N iterations; α is the minimum step value; D m is a position matrix and is represented as ([-1,-1],[-1,0],[-1,1],[0,-1],[0,0],[0,1],[1,-1],[1,0],[1,1]); The case with the smallest reflection coefficient among the nine capacitor combinations can be determined by measurement, which represents the local optimal solution in this iteration. By following this method until the maximum number of iterations is reached, the actual optimal capacitor combination (C r-opt1 , C r-opt2 ), MCU (1) controls the π-type impedance matching network (2) to complete the re-matching and enters step S4; if no new local optimal capacitor combination is found during the iteration process, C N As the actual optimal capacitor combination (C r-opt1 , C r-opt2 ) to match, and directly proceed to step S4; Step S4: dynamically monitor the input impedance of the system at a given frequency using an amplitude and phase measurement circuit. When the input impedance changes beyond a set threshold, proceed to step S1.

2. A fast adaptive impedance matching method according to claim 1, characterized in that: In step S1, the input impedance Z in The calculation formula is: Where: Z0 is the characteristic impedance; Γ is the reflection coefficient.

3. A fast adaptive impedance matching method according to claim 2, characterized in that: In step S1, the MCU (1) adjusts the input impedance Z by changing the capacitance of the adjustable capacitor C1 and the adjustable capacitor C2 in the π-type impedance matching network (2). in The system is adjusted to match the input impedance Z. in The calculation formula is: Where: Z L To match the input impedance when the load (9) is short-circuited; ω is the angular frequency of the system; L is the series inductance in the π-type impedance matching network (2); Two groups of theoretical optimal capacitance combinations are calculated using formula (2) and formula (3), and one group is a pseudo value.

4. A fast adaptive impedance matching system, based on a fast adaptive impedance matching method according to any one of claims 1 to 3, characterized in that: The invention comprises a signal source (3), an amplitude phase measurement circuit, a π-type impedance matching network (2) and an MCU (1); the signal source (3) is connected to the π-type impedance matching network (2) through the amplitude phase measurement circuit; the MCU (1) is respectively connected to the amplitude phase measurement circuit and each relay switch of the π-type impedance matching network (2); the amplitude phase measurement circuit comprises a dual directional coupler (4), an attenuator (5) and an AD8302 chip (6); the input end and the through end of the dual directional coupler (4) are respectively connected to the output end of the signal source (3) and the input end of the π-type impedance matching network (2); and the coupling end and the isolation end of the dual directional coupler (4) are respectively connected to the input port of the AD8302 chip (6) through the attenuator (5); and the amplitude and phase detection end of the AD8302 chip (6) is connected to the universal input port of the MCU (1).

5. A fast adaptive impedance matching system according to claim 4, characterized in that: The signal source (3) comprises a signal generator and a power amplifier, and the signal transmitter is connected to the input end of the dual directional coupler (4) via the power amplifier.

6. A fast adaptive impedance matching system according to claim 4, characterized in that: The π-type impedance matching network (2) comprises a fixed-value inductor L and adjustable capacitors C1 and C2. The left and right sides of the fixed-value inductor L are respectively connected in parallel with the adjustable capacitors C1 and C2. The adjustable capacitors C1 and C2 are respectively composed of N capacitors C n-i In parallel, each capacitor C n-i (n=1, 2, i=1, 2, ... N) is connected to a relay switch, the relay switch is connected to MCU (1), and a capacitor C n-i Equal to 2 of the minimum step capacitance value i-1 times.

7. A wireless power transmission system, comprising a fast adaptive impedance matching system according to any one of claims 4 to 6, characterized in that: It also includes a receiving end and a transmitting end, and the output end of the π-type impedance matching network (2) is connected to the transmitting end.

8. A wireless power transmission system according to claim 7, characterized in that: The receiving end includes a receiving coil (7), a resonant capacitor C r2 and load (9), the resonant capacitor C r2 A receiving coil (7) and a load (9) are respectively arranged in series on both sides; a transmitting coil (8) and a resonant capacitor C are correspondingly arranged on the transmitting end. r1 , the resonant capacitor C r1 A transmitting coil (8) and a π-type impedance matching network (2) are respectively arranged in series on both sides.

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