A mutual inductance-based radio frequency automatic impedance matching network structure and system

Abstract

The application discloses a kind of based on mutual inductance coupling radio frequency automatic impedance matching network structure and system, belong to radio frequency matcher technical field.The network structure includes input port, output port, and input pre-tuning branch, mutual inductance coupling impedance transformation core branch and output fine tuning branch sequentially arranged between input port and output port along signal flow direction;Input port is used to connect radio frequency power supply, and output port is used to connect load;Input pre-tuning branch includes the first adjustable capacitor connected to input port in parallel, for the inductive reactance at input port is compensated;Mutual inductance coupling impedance transformation core branch includes main coil, secondary coil and the second adjustable capacitor connected to main coil in parallel, and main coil and the second adjustable capacitor constitute parallel resonance loop;Output fine tuning branch includes third adjustable capacitor, and third adjustable capacitor is connected between secondary coil and output port in series, for the reactance on load side is compensated.

Description

Technical Field

[0001] This application relates to the field of radio frequency matching technology, and more specifically, to a radio frequency automatic impedance matching network structure and system based on mutual inductance coupling. Background Technology

[0002] Power radio frequency (RF) sources are widely used in vacuum deposition, semiconductor etching, and induction heating plasma. Typically, the load impedance is not equal to the RF source's internal resistance. Directly connecting the RF source and load results in varying degrees of impedance mismatch. Impedance mismatch leads to power reflection on the transmission line, preventing the load from absorbing all the energy and reducing transmission efficiency. Therefore, a matching network is usually required between the RF source (or the end of the transmission line) and the load. Since the load impedance varies within a certain range due to factors such as operating time, process progress, and the surrounding environment, maximum transmission efficiency can only be achieved by real-time detection of load impedance changes and corresponding adjustments to the matching network parameters. Therefore, research on automatic impedance matching devices is particularly important.

[0003] Automatic impedance matching devices can track the complex impedance changes of the plasma load in a timely manner, ensuring impedance matching between the load and the RF source, thereby ensuring that the power output by the RF source can be fully absorbed by the plasma load. For example... Figure 1 As shown, existing automatic impedance matching systems typically consist of four functional modules: an impedance detection module, a computer signal processing module, a motor control module, and a matching network. The RF power supply is connected to the load port, i.e., the plasma device, via the matching network. Common matching networks often employ an L-shaped structure. While the L-shaped matching network structure is the simplest, it suffers from drawbacks such as an unadjustable quality factor (Q), narrow bandwidth, sensitivity to parasitic parameters, and poor resistance to load fluctuations. These shortcomings are amplified dramatically in high-frequency, low-resistance, and high-power applications, generally limiting its application to simple, single-frequency, small-signal, and relatively stable loads.

[0004] In addition, although RF automatic impedance matching networks based on mutual inductance coupling can be used to connect RF power supplies and process chamber loads, transforming the complex impedance of the chamber that changes dynamically with the process into the standard impedance required by the RF power supply (usually 50Ω), achieving conjugate matching, maximum power transfer and low VSWR, and are widely used in semiconductor RF processes such as plasma coating and etching, the existing structures still need to be improved in terms of matching range, electrical isolation capability, tuning accuracy and high power adaptation capability, and cannot yet meet the requirements of long-term stable and high-precision impedance matching in semiconductor plasma processes. Summary of the Invention

[0005] In order to overcome a series of defects in the existing technology, the purpose of this application is to provide a radio frequency automatic impedance matching network structure based on mutual inductance coupling, which includes an input port, an output port, and an input pre-tuning branch, a mutual inductance coupling impedance transformation core branch, and an output fine-tuning branch arranged sequentially between the input port and the output port along the signal flow direction; the input port is used to connect to the radio frequency power supply, and the output port is used to connect to the load; The input pre-tuning branch includes a first adjustable capacitor connected in parallel to the input port for compensating the inductive reactance at the input port; The core branch of the mutual inductance coupling impedance transformation includes a main coil, a secondary coil, and a second adjustable capacitor connected in parallel with the main coil. The main coil and the second adjustable capacitor form a parallel resonant circuit. There is no direct electrical connection between the secondary coil and the main coil; energy transfer and impedance transformation are achieved only through magnetic field coupling. The output fine-tuning branch includes a third adjustable capacitor, which is connected in series between the secondary coil and the output port to compensate for the reactance on the load side.

[0006] In some embodiments, the resonant frequency of the parallel resonant circuit is configured to be close to the operating frequency of the RF power supply so that when the parallel resonant circuit operates in the resonant state, the equivalent impedance of the main coil exhibits pure resistivity.

[0007] In some embodiments, the load impedance on the secondary coil side is reflected to the primary coil side based on the mutual inductive coupling between the primary and secondary coils, forming a reflected impedance. The ratio of the reflected impedance to the load impedance on the secondary coil side is equal to the square of the ratio of the number of turns in the primary coil to the number of turns in the secondary coil.

[0008] In some embodiments, the third adjustable capacitor is used to compensate for the residual inductive reactance of the secondary coil due to mutual inductive coupling, so as to adjust the imaginary part of the equivalent impedance on the load side and make the equivalent impedance on the load side approach pure resistivity.

[0009] In some embodiments, a motor drive mechanism is further included, which is connected to the first adjustable capacitor, the second adjustable capacitor, and the third adjustable capacitor respectively. The motor drive mechanism is used to drive the corresponding adjustable capacitor to adjust the capacitance value.

[0010] The purpose of this application is also to provide a radio frequency automatic impedance matching system based on mutual inductance coupling, including a power detection module, a computer signal processing module, an execution module, and the above-mentioned radio frequency automatic impedance matching network structure: The power detection module is used to acquire the incident power signal and reflected power signal between the RF power supply and the RF automatic impedance matching network structure; The computer signal processing module is connected to the power detection module and is used to calculate the load impedance based on the incident power signal and the reflected power signal, and to generate control information based on the load impedance. The execution module is connected to the computer signal processing module and is used to drive the corresponding adjustable capacitor in the RF automatic impedance matching network structure to adjust the capacitance value according to the control information.

[0011] In some embodiments, the computer signal processing module includes a signal processing module, an interface module, an impedance calculation module, and a control module. The signal processing module is used to process the incident power signal and the reflected power signal; the impedance calculation module is used to calculate the real and imaginary parts of the load impedance based on the processed signal; the interface module is used to transmit the control information obtained based on the load impedance to the control module; and the control module is used to control the action of the execution module.

[0012] In some embodiments, the power detection module is configured to perform the following steps in sequence: The induced power signal is acquired on the transmission line between the RF power supply and the input port of the RF automatic impedance matching network structure. The induced power signal is analyzed and processed, and the signal is separated according to the transmission direction of the induced power signal to obtain the incident power signal and the reflected power signal; The incident power signal and the reflected power signal are output to the computer signal processing module respectively.

[0013] In some embodiments, the impedance calculation module and the control module are configured to perform the following steps sequentially: Obtain the real and imaginary parts of the load impedance and compare them with the real and imaginary parts of the preset standard impedance to obtain the impedance deviation between the load impedance and the standard impedance. The target adjustment position, adjustment direction, and adjustment step size of the first, second, and third adjustable capacitors are determined based on the impedance deviation. The corresponding drive control signal is generated according to the preset adjustment sequence, and each adjustable capacitor is adjusted according to the drive control signal so that the output impedance of the RF automatic impedance matching network matches the standard impedance.

[0014] In some embodiments, the control module is configured to perform the following steps sequentially: Keep the current adjustment state of the third adjustable capacitor unchanged, and control the first and second adjustable capacitors to adjust so that the deviation between the real part of the load impedance and the real part of the standard impedance meets the preset matching condition. After the real part of the load impedance satisfies the preset matching condition, the compensation adjustment amount of the third adjustable capacitor is determined according to the deviation between the imaginary part of the load impedance and the imaginary part of the standard impedance, and the third adjustable capacitor is controlled to perform compensation adjustment. Based on the compensated and adjusted load impedance parameters, the deviation between the imaginary part of the load impedance and the imaginary part of the standard impedance is re-evaluated, and the compensation adjustment is cyclically performed according to the evaluation result until both the real part and the imaginary part of the load impedance meet the preset matching conditions.

[0015] Compared with the prior art, this application has the following beneficial effects: 1) Wider matching range: The mutual inductance coupling structure combined with three-stage adjustable capacitors can cover the impedance variation range of the entire operating condition, including before plasma ignition, at the moment of ignition, stable discharge, and process fluctuations. This expands the adaptability range to dynamic loads and avoids the mismatch problem caused by the narrow matching range of L-type networks.

[0016] 2) Superior electrical isolation: The main coil and the auxiliary coil are completely electrically isolated through magnetic field coupling, which can effectively block the conduction of high voltage, arcing surge, DC leakage current and stray interference from the cavity side to the RF power supply, protect the core components of the RF power amplifier, and improve the system's operational safety and anti-interference capability.

[0017] 3) Higher tuning accuracy: The three-level decoupled tuning architecture has a clear division of labor, and can independently adjust the real and imaginary parts of the impedance. Combined with the motor drive, it can achieve precise compensation, maintain a low reflection power and a stable standing wave ratio for a long time, and improve the uniformity and yield of the plasma process.

[0018] 4) Larger power capacity: Power is distributed through the magnetic field of the coil, the stress on the tuning capacitor is dispersed, the coil can adopt a large wire diameter design to avoid core saturation, and it can stably adapt to industrial high-power RF scenarios of hundreds of watts to thousands of watts, and is less prone to problems such as device breakdown and overheating.

[0019] 5) Enhanced system stability: The three-stage decoupling design improves the linearity of impedance regulation, accelerates the automatic tuning convergence of the motor, and reduces the likelihood of tuning oscillations and tuning skipping. It can stably adapt to the subtle fluctuations of the cavity's dynamic load over a long period of time. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an existing automatic impedance matching system. Figure 2 This is a schematic diagram of the automatic impedance matching system based on mutual inductance coupling of the present invention. Figure 3 This is a schematic diagram of the radio frequency automatic impedance matching network structure based on mutual inductance coupling of the present invention; Figure 4 This is a block diagram of the automatic impedance matching system based on mutual inductance coupling of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0022] like Figure 2 As shown, the automatic impedance matching system based on mutual inductance coupling provided by this invention is divided into four functional modules: a power detection module, a computer signal processing module, an execution module (motor control module), and a matching network. The radio frequency power supply is ultimately connected to the plasma device (load) via the matching network. The power detection module collects the power signal induced on the coaxial cable and separates it into incident power signal and reflected power signal, which are then transmitted to the computer signal processing module for processing, thereby controlling the rotation of the motor. The motor is connected to a first adjustable capacitor C1, a second adjustable capacitor C2, and a third adjustable capacitor C3. By controlling the adjustment of these adjustable capacitors, the system circuit achieves the optimal impedance matching state. As the impedance gradually changes during the process, the power detection module detects it in real time and transmits the signal to the computer signal processing module. The motor controls the capacitor value in real time, enabling the system to reach the matching state in real time as the process progresses, thereby achieving automatic matching during operation, reducing operational complexity, and improving overall work efficiency.

[0023] like Figure 3 As shown, the RF automatic impedance matching network structure of the present invention is divided into three parts according to the signal flow direction: input pre-tuning branch, mutual inductance coupling impedance transformation core branch, and output fine tuning branch. The variable capacitors in each branch are driven by motors, and the main and secondary coils achieve electrical isolation and impedance transformation through mutual inductance coupling.

[0024] The input pre-tuning branch consists of a vacuum variable capacitor C1, connected in parallel to the input port, and its function is to coarsely adjust the impedance. The cavity plasma load is inductive overall, and when reflected to the input terminal through mutual inductive coupling, it presents inductive reactance. The motor drives C1 to change its capacitance, thereby adjusting the capacitance of the parallel branch: when the capacitance increases, the capacitive susceptance increases, which can offset the inductive reactance at the input terminal / transmission line; when the capacitance decreases, the capacitive compensation decreases. This achieves a first-stage coarse matching of the RF power supply impedance, ensuring that power can efficiently enter the main coil and avoiding input impedance detuning.

[0025] The core branch of the mutual inductance coupling impedance transformation consists of the main coil L1, the secondary coil L2, and the vacuum adjustable capacitor C2 connected in parallel with the main coil. According to the high-frequency transformer impedance transformation formula, the mutual inductance impedance satisfies: ， In the formula, The number of turns of the main coil L1, The number of turns of the secondary coil L2. This refers to the cavity load impedance. The reflection from the secondary coil L2 to the primary coil L1 via mutual inductance coupling manifests as a reflected impedance. Its equivalent impedance is amplified; by amplifying the impedance through the turns ratio, the load impedance can be matched to the vicinity of the 50Ω standard impedance of the RF power supply, thus solving the problem of insufficient impedance transformation range of a simple L-type network.

[0026] The main coil L1 is connected in parallel with the second adjustable capacitor C2 driven by the motor, forming a parallel LC resonant circuit. The motor adjusts the capacitance of C2 to change the resonant frequency of this circuit, configuring it to be close to the 13.56MHz operating frequency of the RF power supply. When the resonant circuit operates at resonance, the inductive reactance of the main coil L1 is completely canceled out by the capacitor, and the main coil side exhibits pure resistivity. When the resonant point deviates, capacitive or inductive reactance is introduced to adjust the imaginary part of the reflected impedance. This achieves a two-stage core tuning of the real and imaginary parts of the reflected impedance, serving as the impedance adjustment core of the entire matching network.

[0027] It should be noted that there is no direct electrical connection between the main coil L1 and the auxiliary coil L2. Energy transfer and impedance transformation are achieved only through magnetic field coupling. High voltage, DC leakage, plasma stray interference, and cavity arcing surges on the cavity side cannot be directly conducted to the RF power supply, thus protecting the core components of the RF power amplifier. This is one of the core advantages of this structure that distinguishes it from ordinary L-type matching networks.

[0028] The fine-tuning output branch consists of a variable vacuum capacitor C3, which is connected in series between the secondary coil L2 and the cavity (output port) to precisely compensate for the residual reactance on the cavity side. The cavity induction coil is inductive overall, but after the plasma ignites, a capacitive component is introduced, causing a dynamic shift in the overall reactance on the cavity side. The motor adjusts the capacitance of C3 within a small range to precisely compensate for the inductive / capacitive reactance on the cavity side, offsetting the residual inductive reactance generated by the mutual inductive coupling of the secondary coil L2. This makes the imaginary part of the equivalent impedance on the load side approach zero and the real part approach precise matching, thus completing the final impedance conjugate matching and making the cavity load equivalent to a purely resistive load of about 50Ω.

[0029] By analyzing the overall structure of the matching network, the equivalent load of the matching network can be calculated. Considering only the main coil side, we have: ; After simplification, we get: In the formula, The internal resistance of the RF power supply. , , This is the operating angular frequency.

[0030] For mutual inductance coils L1 and L2, the turns ratio n satisfies: ; Therefore, the equivalent load of the matching network as a whole can be obtained. for: .

[0031] Further expansion yields: To maximize transmission power, the equivalent load of the matching network should be conjugate to the load impedance, meaning their real parts are equal and their imaginary parts are opposite. The load impedance... Defined as consisting of two parts: real part R and imaginary part X, then: .

[0032] The equivalent load of the matching network is conjugate with the load impedance, i.e. We can obtain: In the overall system architecture, the internal resistance of the RF power supply is a fixed value, determined solely by the RF power supply itself, and is usually assumed to be fixed in practical applications. =50Ω. By adjusting the adjustable capacitors within the matching network to accommodate actual changes in load impedance, the overall circuit can achieve a matched state, maximizing power transmission.

[0033] In one optional embodiment, the first adjustable capacitor C1, the second adjustable capacitor C2, and the third adjustable capacitor C3 are all vacuum variable capacitors, which have the characteristics of high voltage resistance, low loss, and high reliability, making them suitable for high-power radio frequency applications. The radio frequency automatic impedance matching network structure also includes a motor drive mechanism connected to C1, C2, and C3 respectively, for driving the corresponding adjustable capacitors to adjust their capacitance values.

[0034] Example 1 like Figure 4 As shown, the overall structure of the automatic impedance matching system based on mutual inductance coupling provided by this invention consists of a power detection module, a computer signal processing module, an execution module, and a matching network. The computer signal processing module includes a signal processing module, an interface module, an impedance calculation module, and a control module; the execution module includes a motor drive unit and a motor unit; and the matching network includes mutual inductance coils and adjustable vacuum capacitors (corresponding to the main coil L1, secondary coil L2, and the first adjustable capacitor C1, second adjustable capacitor C2, and third adjustable capacitor C3 mentioned above, respectively). A detailed description follows: The power detection module acquires the induced power signal on the transmission line between the input port of the RF power supply and the matching network, analyzes and processes the induced power signal, and separates it into the incident power signal corresponding to the output direction of the RF power supply and the reflected power signal corresponding to the reflection direction of the load according to the power transmission direction, and outputs the two to the computer signal processing module respectively.

[0035] The signal processing module in the computer signal processing module processes the incident power signal and the reflected power signal. The impedance calculation module calculates the real and imaginary parts of the load impedance based on the processed signals, and then calculates the load impedance. Defined as: .

[0036] Analysis of the equivalent impedance of the matching network and the RF source shows that: After obtaining the real and imaginary parts of the load impedance, the impedance calculation module compares them with the real and imaginary parts corresponding to the preset standard impedance to obtain the impedance deviation between the load impedance and the standard impedance. Based on this impedance deviation, the module calculates the adjustment deviation between the current position and the target position of the first adjustable capacitor C1, the second adjustable capacitor C2, and the third adjustable capacitor C3, and determines the adjustment direction and adjustment step size for each adjustable capacitor accordingly. The interface module transmits the control information obtained from the load impedance to the control module. The control module generates drive control signals corresponding to C1, C2, and C3 sequentially according to the preset adjustment sequence to control the action of the execution module.

[0037] It should be noted that, since there may be multiple solutions that meet the conditions when automatically adjusting the three adjustable capacitors C1, C2, and C3, in practical applications, since the current inductor is fixed, the control module prioritizes fixing the third adjustable capacitor C3. Initial adjustment is performed at the main coil using the first and second adjustable capacitors C1 and C2 to ensure that the real part of the load impedance meets the preset matching conditions. After the real part of the load impedance meets the preset matching conditions, the third adjustable capacitor C3 is controlled to perform compensation adjustment based on the deviation between the imaginary part of the load impedance and the imaginary part of the standard impedance. Based on the compensated load impedance, the imaginary part matching judgment and compensation adjustment are repeatedly performed until both the real and imaginary parts of the load impedance meet the preset matching conditions, thus realizing a single-sided fixed, graded adjustment matching strategy.

[0038] After receiving the control information output by the computer signal processing module, the execution module generates drive electrical signals corresponding to C1, C2, and C3 respectively based on the control information. The motor drive unit controls the corresponding motor unit to operate according to each drive electrical signal, and drives the corresponding adjustable capacitor to operate through the independent transmission structure set for each motor unit. Based on the operation results of each adjustable capacitor, the capacitance values ​​of the first adjustable capacitor C1, the second adjustable capacitor C2, and the third adjustable capacitor C3 are adjusted, so that the load impedance is matched to the standard impedance, thereby achieving the goal of maximizing the transmission power.

[0039] The aforementioned RF automatic impedance matching network structure and automatic impedance matching system based on mutual inductance coupling described in this application coarsely compensates the inductive reactance of the RF power supply side through the input pre-tuning branch, and combines it with the parallel resonant tuning of the core branch of mutual inductance coupling impedance transformation to ensure that the real and imaginary parts of the load reflected impedance can be quickly and accurately adjusted to the preset matching range. Through the output fine-tuning branch, the residual inductance of the secondary coil is precisely compensated, reducing the impact of dynamic changes in cavity load impedance on matching accuracy and detection sensitivity. On this basis, efficient, continuous, and stable transmission of RF power is achieved under all operating conditions of plasma processes, thereby significantly improving the matching response speed, operational reliability, and matching accuracy of the automatic impedance matching system in high-power, low-resistance application scenarios, meeting the requirements of long-term high-precision impedance matching for processes such as semiconductor plasma coating and etching.

[0040] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention shall be covered by the present invention.

Claims

1. A radio frequency automatic impedance matching network structure based on mutual inductance coupling, characterized in that, It includes an input port, an output port, and an input pre-tuning branch, a mutual inductance coupling impedance transformation core branch, and an output fine-tuning branch arranged sequentially between the input port and the output port along the signal flow direction; the input port is used to connect to the RF power supply, and the output port is used to connect to the load; The input pre-tuning branch includes a first adjustable capacitor connected in parallel to the input port for compensating the inductive reactance at the input port; The core branch of the mutual inductance coupling impedance transformation includes a main coil, a secondary coil, and a second adjustable capacitor connected in parallel with the main coil. The main coil and the second adjustable capacitor form a parallel resonant circuit. There is no direct electrical connection between the secondary coil and the main coil; energy transfer and impedance transformation are achieved only through magnetic field coupling. The output fine-tuning branch includes a third adjustable capacitor, which is connected in series between the secondary coil and the output port to compensate for the reactance on the load side.

2. The radio frequency automatic impedance matching network structure according to claim 1, characterized in that, The resonant frequency of the parallel resonant circuit is configured to be close to the operating frequency of the RF power supply so that when the parallel resonant circuit is in the resonant state, the equivalent impedance of the main coil exhibits pure resistivity.

3. The radio frequency automatic impedance matching network structure according to claim 1, characterized in that, The load impedance on the secondary coil side is reflected to the primary coil side based on the mutual inductive coupling between the primary and secondary coils, forming a reflected impedance. The ratio of the reflected impedance to the load impedance on the secondary coil side is equal to the square of the ratio of the number of turns of the primary coil to the number of turns of the secondary coil.

4. The radio frequency automatic impedance matching network structure according to claim 1, characterized in that, The third adjustable capacitor is used to compensate for the residual inductive reactance of the secondary coil due to mutual inductive coupling, so as to adjust the imaginary part of the equivalent impedance on the load side and make the equivalent impedance on the load side approach pure resistivity.

5. The radio frequency automatic impedance matching network structure according to claim 1, characterized in that, It also includes a motor drive mechanism that is connected to the first adjustable capacitor, the second adjustable capacitor and the third adjustable capacitor respectively. The motor drive mechanism is used to drive the corresponding adjustable capacitor to adjust the capacitance value.

6. A radio frequency automatic impedance matching system based on mutual inductance coupling, comprising a power detection module, a computer signal processing module, an execution module, and a radio frequency automatic impedance matching network structure as described in any one of claims 1-5, characterized in that: The power detection module is used to acquire the incident power signal and reflected power signal between the RF power supply and the RF automatic impedance matching network structure; The computer signal processing module is connected to the power detection module and is used to calculate the load impedance based on the incident power signal and the reflected power signal, and to generate control information based on the load impedance. The execution module is connected to the computer signal processing module and is used to drive the corresponding adjustable capacitor in the RF automatic impedance matching network structure to adjust the capacitance value according to the control information.

7. The radio frequency automatic impedance matching system according to claim 6, characterized in that, The computer signal processing module includes a signal processing module, an interface module, an impedance calculation module, and a control module. The signal processing module is used to process the incident power signal and the reflected power signal; the impedance calculation module is used to calculate the real and imaginary parts of the load impedance based on the processed signal; the interface module is used to transmit the control information obtained based on the load impedance to the control module; and the control module is used to control the actions of the execution module.

8. The radio frequency automatic impedance matching system according to claim 6, characterized in that, The power detection module is configured to perform the following steps sequentially: The induced power signal is acquired on the transmission line between the RF power supply and the input port of the RF automatic impedance matching network structure. The induced power signal is analyzed and processed, and the signal is separated according to the transmission direction of the induced power signal to obtain the incident power signal and the reflected power signal; The incident power signal and the reflected power signal are output to the computer signal processing module respectively.

9. The radio frequency automatic impedance matching system according to claim 6, characterized in that, The impedance calculation module and the control module are configured to execute the following steps sequentially: Obtain the real and imaginary parts of the load impedance and compare them with the real and imaginary parts of the preset standard impedance to obtain the impedance deviation between the load impedance and the standard impedance. The target adjustment position, adjustment direction, and adjustment step size of the first, second, and third adjustable capacitors are determined based on the impedance deviation. The corresponding drive control signal is generated according to the preset adjustment sequence, and each adjustable capacitor is adjusted according to the drive control signal so that the output impedance of the RF automatic impedance matching network matches the standard impedance.

10. The radio frequency automatic impedance matching system according to claim 6, characterized in that, The control module is configured to execute the following steps sequentially: Keep the current adjustment state of the third adjustable capacitor unchanged, and control the first and second adjustable capacitors to adjust so that the deviation between the real part of the load impedance and the real part of the standard impedance meets the preset matching condition. After the real part of the load impedance satisfies the preset matching condition, the compensation adjustment amount of the third adjustable capacitor is determined according to the deviation between the imaginary part of the load impedance and the imaginary part of the standard impedance, and the third adjustable capacitor is controlled to perform compensation adjustment. Based on the compensated and adjusted load impedance parameters, the deviation between the imaginary part of the load impedance and the imaginary part of the standard impedance is re-evaluated, and the compensation adjustment is cyclically performed according to the evaluation result until both the real part and the imaginary part of the load impedance meet the preset matching conditions.

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