Impedance matching circuit, ultrasonic transducer system and ultrasonic self-cleaning equipment

Abstract

The invention discloses an impedance matching circuit, an ultrasonic transducer system, ultrasonic self-cleaning equipment, an impedance matching method, an impedance matching device, an impedance matching system and a computer readable storage medium. The impedance matching circuit includes at least one impedance matching element and at least one switching element. Each impedance matching element and the corresponding switch element are connected between the transducer driving frequency input end and the ultrasonic transducer. And each switch element is used for conducting or cutting off, so that the impedance matching circuit is matched with the impedance of the ultrasonic transducer. In the embodiment of the invention, the impedance matching element can be dynamically selected through the conduction and cut-off of each switch element, and automatic and accurate impedance matching between the impedance matching circuit and the ultrasonic transducer can be realized without manual intervention.

Description

Technical Field

[0001] The present application relates to the field of impedance matching technology, and in particular to an impedance matching circuit, an ultrasonic transducer system, an ultrasonic self-cleaning device, an impedance matching method, an impedance matching device, an impedance matching system, and a computer-readable storage medium. Background Art

[0002] An ultrasonic transducer system typically consists of a drive circuit, an impedance matching circuit, and an ultrasonic transducer. Only when the impedance matching circuit matches the ultrasonic transducer impedance will the overall impedance of the ultrasonic transducer system be minimized and the system operate optimally. However, when the ultrasonic transducer and the impedance matching circuit change due to the operating environment, the impedance point of the entire ultrasonic transducer system may shift, causing the impedance matching circuit to fail to achieve impedance matching with the ultrasonic transducer. Summary of the Invention

[0003] The embodiments of the present application provide an impedance matching circuit, an ultrasonic transducer system, an ultrasonic self-cleaning device, an impedance matching method, an impedance matching device, an impedance matching system and a computer-readable storage medium to solve at least one of the above-mentioned technical problems.

[0004] The impedance matching circuit of the embodiment of the present application includes at least one impedance matching element and at least one switching element. Each impedance matching element and a corresponding switching element are connected between the transducer drive frequency input terminal and the ultrasonic transducer. Each switching element is used to be turned on or off so that the impedance matching circuit matches the impedance of the ultrasonic transducer.

[0005] In some embodiments, each of the impedance matching elements is a matching inductor, and the impedance matching circuit further includes a fixed capacitor connected to the ultrasonic transducer.

[0006] In some embodiments, each of the impedance matching elements is a matching capacitor, and the impedance matching circuit further includes a fixed inductor connected to the ultrasonic transducer.

[0007] In some embodiments, there are multiple impedance matching elements, some of which are matching inductors, and some of which are matching capacitors.

[0008] In some embodiments, each of the switch elements is configured to receive a control signal sent by a control unit, and the control signal is configured to control an on-off state of the switch element.

[0009] In some embodiments, each of the switching elements includes a first connection end, a second connection end, a control end, and a ground end, wherein the first connection end is used to connect to the transducer driving frequency input end, the second connection end is used to connect to the impedance matching element, the control end is used to receive the control signal, and the ground end is used for grounding.

[0010] In some embodiments, the impedance matching circuit further includes at least one current-limiting resistor, and each of the switching elements is connected to the control unit via a corresponding current-limiting resistor.

[0011] The ultrasonic transducer system according to the embodiment of the present application includes:

[0012] Ultrasonic transducers; and

[0013] The impedance matching circuit of any of the above embodiments is configured to perform impedance matching with the ultrasonic transducer.

[0014] In some embodiments, the ultrasonic transducer system further includes a driving circuit configured to provide a driving frequency signal for the ultrasonic transducer.

[0015] The ultrasonic self-cleaning device of the embodiment of the present application includes the ultrasonic transducer system of any of the above embodiments.

[0016] The impedance matching method of the embodiment of the present application is applied to the impedance matching circuit of any of the above embodiments, and the impedance matching method includes:

[0017] Obtain the frequency point corresponding to the minimum impedance point of the ultrasonic transducer;

[0018] Calculating the impedance matching value required in the impedance matching circuit according to the frequency point;

[0019] The on-off states of the plurality of switch elements are controlled according to the impedance matching value, so that the impedance matching circuit matches the impedance of the ultrasonic transducer.

[0020] In some embodiments, the impedance matching method further includes:

[0021] Determining whether the frequency point is offset;

[0022] The calculating the impedance matching value required in the impedance matching circuit according to the frequency point includes:

[0023] When the frequency point shifts, the impedance matching value is calculated according to the frequency point.

[0024] In some embodiments, the impedance matching value includes a matching inductance value and / or a matching capacitance value.

[0025] The impedance matching device of the embodiment of the present application is applied to the impedance matching circuit of any of the above embodiments, and the impedance matching device includes:

[0026] An acquisition module, used to obtain the frequency point corresponding to the minimum impedance point of the ultrasonic transducer;

[0027] A calculation module, configured to calculate an impedance matching value required in the impedance matching circuit according to the frequency point;

[0028] A control module is used to control the on-off states of the plurality of switch elements according to the impedance matching value, so that the impedance matching circuit matches the impedance of the ultrasonic transducer.

[0029] The impedance matching system of the embodiment of the present application includes one or more processors and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, the impedance matching method of any of the above embodiments is implemented.

[0030] The computer-readable storage medium of the embodiment of the present application stores a computer program thereon, and when the program is executed by a processor, the impedance matching method of any of the above embodiments is implemented.

[0031] The impedance matching circuit, ultrasonic transducer system, ultrasonic self-cleaning equipment, impedance matching method, impedance matching device, impedance matching system and computer-readable storage medium of the embodiments of the present application can dynamically select impedance matching elements by turning on and off each switching element, and can achieve automatic and accurate impedance matching between the impedance matching circuit and the ultrasonic transducer without human intervention.

[0032] Additional aspects and advantages of the embodiments of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0034] Figure 1 is a schematic diagram of a module of an ultrasonic transducer system according to certain embodiments of the present application;

[0035] Figure 2 is a schematic diagram of the circuit structure of an ultrasonic transducer system according to certain embodiments of the present application;

[0036] Figure 3 is a schematic diagram of the circuit structure of an ultrasonic transducer system according to certain embodiments of the present application;

[0037] Figure 4 is a schematic diagram of the circuit structure of an ultrasonic transducer system according to certain embodiments of the present application;

[0038] Figure 5 is a schematic diagram of a module of an ultrasonic self-cleaning device according to certain embodiments of the present application;

[0039] Figure 6 is a flow chart of an impedance matching method according to certain embodiments of the present application;

[0040] Figure 7 is a flow chart of an impedance matching method according to certain embodiments of the present application;

[0041] Figure 8 is a schematic diagram of a module of an impedance matching device according to certain embodiments of the present application;

[0042] Figure 9 is a schematic diagram of a module of an impedance matching device according to certain embodiments of the present application;

[0043] Figure 10 is a schematic diagram of a module of an impedance matching system according to certain embodiments of the present application;

[0044] Figure 11 This is a schematic diagram of the connection status between a computer-readable storage medium and a processor in certain embodiments of the present application.

[0045] Description of reference numerals:

[0046] Impedance matching circuit 100, impedance matching element 10, switching element 20, current limiting resistor 30, ultrasonic transducer 200, driving circuit 300, control unit 400, ultrasonic transducer system 500, ultrasonic self-cleaning equipment 1000, impedance matching device 2000, acquisition module 2100, calculation module 2200, control module 2300, judgment module 2400, impedance matching system 3000, processor 3100, memory 3200, computer-readable storage medium 4000, computer program 4100, processor 4200. DETAILED DESCRIPTION

[0047] The following further describes the embodiments of the present application in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions. Furthermore, the embodiments of the present application described below in conjunction with the accompanying drawings are exemplary and are intended only to explain the embodiments of the present application and are not to be construed as limiting the present application.

[0048] An ultrasonic transducer system typically consists of a drive circuit, an impedance matching circuit, and an ultrasonic transducer. The impedance matching circuit often uses an inductor and a capacitor to form an LC resonant circuit. Only when the LC resonant circuit matches the impedance of the ultrasonic transducer will the overall impedance of the ultrasonic transducer system be minimized and the ultrasonic transducer system can operate at its optimal state. When the ultrasonic transducer and the impedance matching circuit change due to changes in the operating environment, such as changes in the ambient temperature, changes in attachments on the ultrasonic transducer, parameter shifts caused by long-term use of the ultrasonic transducer and the impedance matching circuit, and fatigue, the impedance point of the entire ultrasonic transducer system will shift, resulting in the impedance matching circuit being unable to achieve optimal impedance matching with the ultrasonic transducer. Manual tuning is the only way to achieve the optimal working state of the ultrasonic transducer.

[0049] Research has found that impedance matching can be achieved by adjusting the ultrasonic transducer's drive frequency, allowing it to operate at its resonant frequency. The entire system consists of a microprocessor control unit, a power supply module, a dual-channel PWM signal high-speed drive enhancement circuit module, a high-frequency transformer, a push-pull output drive circuit, an ultrasonic transducer impedance matching circuit, a push-pull output drive current sampling circuit, and a high-frequency transformer output voltage sampling circuit.

[0050] The circuit operates as follows: A microprocessor control unit generates two PWM signals with dead-band control within a preset frequency range. After amplification and enhancement by a high-speed drive enhancement circuit module, these signals are connected to the gates of two MOS transistors in the push-pull output drive circuit, controlling the on / off switching of the two MOS transistors to amplify power. The PWM signals, amplified by the push-pull output drive circuit, are then coupled to the ultrasonic transducer via a high-frequency transformer, generating a high-frequency, high-voltage signal to drive the transducer. Current and voltage sampling circuits acquire voltage and current data at the current frequency and send them to the microprocessor control unit for algorithmic processing. This algorithm determines the relationship between the voltage and current and the minimum impedance point of the ultrasonic transducer, thereby determining the optimal resonant frequency of the ultrasonic transducer. The inductor and capacitor values in the LC resonant circuit are then manually adjusted to match the resonant frequency with the minimum impedance point of the ultrasonic transducer. If the minimum impedance point of the ultrasonic transducer shifts during operation, the drive frequency is adjusted to achieve impedance tuning, restoring the transducer to its optimal operating frequency.

[0051] The above technical solution has the following deficiencies: First, when the ultrasonic transducer's impedance point shifts due to certain factors, it is not enough to simply adjust the ultrasonic transducer's driving frequency, and it may even affect the working state of the LC impedance matching circuit. The LC impedance matching circuit and the ultrasonic transducer are a whole system. When the ultrasonic transducer's impedance point changes, it is also necessary to adjust the parameters in the LC impedance matching circuit accordingly so that the entire ultrasonic transducer system achieves optimal impedance matching. Second, when the inductance and capacitance in the LC impedance matching circuit change due to long-term use, temperature changes, or other factors, the impedance point of the entire ultrasonic transducer system will also change. Simply adjusting the ultrasonic transducer's driving frequency will not be enough to adjust the entire ultrasonic transducer system to its optimal working state. Manual intervention is required to manually adjust the inductance and capacitance parameters in the LC impedance matching circuit to match the ultrasonic transducer's impedance point.

[0052] In view of this, the embodiments of the present application provide an impedance matching circuit, an ultrasonic transducer system, an ultrasonic self-cleaning device, an impedance matching method, an impedance matching device, an impedance matching system and a computer-readable storage medium to solve at least one of the above-mentioned technical problems.

[0053] See also Figure 1 The ultrasonic transducer system 500 of the embodiment of the present application includes an ultrasonic transducer 200 and an impedance matching circuit 100. The impedance matching circuit 100 is used for impedance matching with the ultrasonic transducer 200.

[0054] Specifically, ultrasonic transducer 200 can utilize the piezoelectric effect to convert electrical signals into mechanical vibrations, thereby generating ultrasonic waves. Impedance matching circuit 100 can be an LC resonant impedance matching circuit. Impedance matching circuit 100 is connected to ultrasonic transducer 200. By adjusting the parameters of impedance matching circuit 100, impedance matching between impedance matching circuit 100 and ultrasonic transducer 200 can be achieved, thereby minimizing the overall impedance of ultrasonic transducer system 500 and ensuring optimal operation of ultrasonic transducer system 500.

[0055] See also Figure 1 In some embodiments, the ultrasonic transducer system 500 further includes a driving circuit 300 . The driving circuit 300 is configured to provide a driving frequency signal to the ultrasonic transducer 200 .

[0056] The driving frequency signal may be input to the ultrasonic transducer 200 via the transducer driving frequency input terminal described below. The driving circuit 300 may be directly connected to the ultrasonic transducer 200 or connected to the ultrasonic transducer 200 via the impedance matching circuit 100 .

[0057] See also Figures 2 to 4 The impedance matching circuit 100 of the embodiment of the present application includes at least one impedance matching element 10 and at least one switching element 20. Each impedance matching element 10 and a corresponding switching element 20 are connected between the transducer drive frequency input terminal and the ultrasonic transducer 200. Each switching element 20 is used to be turned on or off to achieve impedance matching between the impedance matching circuit 100 and the ultrasonic transducer 200.

[0058] The impedance matching circuit 100 of the embodiment of the present application can dynamically select the impedance matching element 10 by turning on and off each switch element 20, and can achieve automatic and accurate impedance matching between the impedance matching circuit 100 and the ultrasonic transducer 200 without manual intervention.

[0059] Specifically, the number of the impedance matching element 10 can be one or more, and each impedance matching element 10 can be a matching inductor or a matching capacitor. When the number of the impedance matching element 10 is one, the impedance matching element 10 can be a matching inductor; or, the impedance matching element 10 can be a matching inductor. When the number of the impedance matching element 10 is multiple, such as Figure 2 As shown, each impedance matching element 10 can be a matching inductor; or, as shown in FIG. Figure 3 As shown, each impedance matching element 10 can be a matching inductor; or, as shown in FIG. Figure 4 As shown, part of the impedance matching element 10 may be a matching inductor, and part of the impedance matching element 10 may be a matching inductor.

[0060] The number of switching elements 20 may also be one or more. Each switching element 20 may be a solid-state relay (SSR) or other electronic switching device. The embodiment of the present application is described using the example of each switching element 20 being a solid-state relay. A solid-state relay is a switching device composed of an all-electronic circuit and has no mechanical contacts inside. Therefore, it has the advantages of long life, high reliability, fast switching speed, no sparks, and no noise. Other electronic switching devices, such as transistor switches, analog switches, and optocoupler switches, are not limited here.

[0061] It should be noted that the number of impedance matching elements 10 may be equal to the number of switch elements 20, that is, one impedance matching element 10 corresponds to exactly one switch element 20; or the number of impedance matching elements 10 may be less than or equal to the number of switch elements 20, in which case each impedance matching element 10 still has a corresponding switch element 20, such as Figure 2 As shown, there may also be an additional switch element 20 that is not connected to the impedance matching element 10 .

[0062] like Figures 2 to 4As shown, the transducer drive frequency input terminal is represented by COM, and the ultrasonic transducer 200 is represented by a piezoelectric transducer equivalent circuit. In one example, the piezoelectric transducer equivalent circuit may include capacitor C0, capacitor C1, inductor L1, and resistor R1. Capacitor C0 is a static capacitor or clamping capacitor, capacitor C1 is a dynamic capacitor or electromechanical coupling capacitor, inductor L1 is a dynamic inductor or mechanical inductor, and resistor R1 is a mechanical loss resistor or dynamic resistor. The piezoelectric transducer equivalent circuit constructed by capacitor C0, capacitor C1, inductor L1, and resistor R1 can simulate and represent the ultrasonic transducer 200.

[0063] Each impedance matching element 10 is connected to a corresponding switch element 20 between the transducer drive frequency input terminal COM and the ultrasonic transducer 200. For example, the transducer drive frequency input terminal COM is first connected to the switch element 20, which is then connected to the impedance matching element 10, which is then connected to the ultrasonic transducer 200.

[0064] When the corresponding switch element 20 of each impedance matching element 10 is turned on, the impedance matching element 10 is connected to form an LC series resonant circuit. By turning each switch element 20 on and off, the connection of each impedance matching element 10 can be dynamically selected, thereby changing the parameters of the impedance matching circuit 100. This allows for automatic and precise impedance matching between the impedance matching circuit 100 and the ultrasonic transducer 200 without manual intervention.

[0065] See also Figure 2 In some embodiments, each impedance matching element 10 is a matching inductor. The impedance matching circuit 100 further includes a fixed capacitor connected to the ultrasonic transducer 200 .

[0066] Specifically, the number of the impedance matching element 10 can be one or more. Figure 2As shown, the embodiment of the present application is described by taking the number of impedance matching elements 10 as an example, and each impedance matching element 10 is a matching inductor. The multiple matching inductors are respectively represented as L2, L3, L4, L5...Ln. The fixed capacitor is represented as C2. The multiple switching elements 20 are respectively represented as K1, K2, K3, K4, K5...Kn. At this time, one end of the switching elements K1, K2, K3, K4, K5...Kn (specifically pin 4 in the following text) is respectively connected to the transducer drive frequency input terminal COM, and the other end of the switching elements K2, K3, K4, K5...Kn (specifically pin 3 in the following text) is respectively connected to one end of the matching inductors L2, L3, L4, L5...Ln, and the other end of the matching inductors L2, L3, L4, L5...Ln is connected to one end of the fixed capacitor C2 and one end of the ultrasonic transducer 200. The other end of the fixed capacitor C2 and the other end of the ultrasonic transducer 200 can be grounded; or, when the driving circuit 300 adopts upper and lower tube driving, the other end of the fixed capacitor C2 and the other end of the ultrasonic transducer 200 can be connected to the lower tube of the driving circuit 300.

[0067] It is understood that the other end of switch element K1 can be connected directly to one end of fixed capacitor C2 and one end of ultrasonic transducer 200 without connecting to a matching inductor. This is because the piezoelectric transducer's equivalent circuit already includes inductor L1, and inductor L1 and fixed capacitor C2 can resonate, thereby achieving impedance matching. Therefore, in some cases, the matching inductor can be omitted. In this case, switch element K1 can be turned on, and switches K2, K3, K4, K5, ..., Kn can all be turned off.

[0068] The inductance values of multiple matching inductors can be different. For example, matching inductor L2 = 1uH, matching inductor L3 = 2.2uH, matching inductor L4 = 3.3uH, matching inductor L5 = 4.7uH, and so on. Pin 3 of each switching element 20 is connected to a matching inductor with a different inductance value. The corresponding switching element 20 can be selected according to the inductance value required for impedance matching, thereby dynamically selecting whether each matching inductor is connected to achieve the tuning effect of the impedance matching circuit 100; different matching inductors can also be used in parallel combination. By selecting the corresponding switch element 20 combination, automatic and precise adaptation of each inductance value can be achieved.

[0069] See also Figure 3 In some embodiments, each impedance matching element 10 is a matching capacitor. The impedance matching circuit 100 further includes a fixed inductor connected to the ultrasonic transducer 200 .

[0070] Specifically, the number of the impedance matching element 10 can be one or more. Figure 3As shown, the embodiment of the present application is described by taking the number of impedance matching elements 10 as an example, and each impedance matching element 10 is a matching capacitor. The multiple matching capacitors are respectively represented as C2, C3, C4, C5, C6...Cn. The fixed inductor is represented as L2. The multiple switching elements 20 are respectively represented as K1, K2, K3, K4, K5...Kn. At this time, one end of the fixed inductor L2 is connected to the transducer drive frequency input terminal COM, and the other end of the fixed inductor L2 is respectively connected to one end of the switching element K1, K2, K3, K4, K5...Kn (specifically pin 3 in the following text) and the other end of the ultrasonic transducer 200, and the other end of the switching element K1, K2, K3, K4, K5...Kn (specifically pin 4 in the following text) is respectively connected to one end of the matching capacitor C2, C3, C4, C5, C6...Cn. The other ends of the matching capacitors C2, C3, C4, C5, C6...Cn are connected to the other end of the ultrasonic transducer 200 and are grounded together; alternatively, when the driving circuit 300 adopts upper and lower tube driving, the other ends of the matching capacitors C2, C3, C4, C5, C6...Cn are connected to the other end of the ultrasonic transducer 200 and are commonly connected to the lower tube of the driving circuit 300.

[0071] The capacitance values of multiple matching capacitors can be different. For example, matching capacitor C2 = 100nF, matching inductor C3 = 220nF, matching inductor C4 = 470nF, matching inductor C5 = 680nF, matching inductor C6 = 1uF, etc. Pin 4 of each switching element 20 is connected to a matching capacitor with a different capacitance value. The corresponding switching element 20 can be selected according to the capacitance value required for impedance matching, thereby dynamically selecting whether each matching capacitor is connected to achieve the tuning effect of the impedance matching circuit 100; different matching capacitors can also be used in parallel combination, and by selecting the corresponding switch element 20 combination, automatic and precise adaptation of each capacitance value can be achieved.

[0072] See also Figure 4 In some embodiments, there are multiple impedance matching elements 10. Some of the impedance matching elements 10 are matching inductors, and some of the impedance matching elements 10 are matching capacitors.

[0073] Specifically, if Figure 4As shown, the embodiment of the present application is described by taking the number of matching inductors and matching capacitors as an example. The multiple matching inductors are respectively represented as L2, L3, L4, L5...Ln, and the multiple switching elements 20 corresponding to the multiple matching inductors are respectively represented as L_K1, L_K2, L_K3, L_K4, L_K5...L_Kn. The multiple matching capacitors are respectively represented as C2, C3, C4, C5, C6...Cn. The multiple switching elements 20 corresponding to the multiple matching inductors are respectively represented as C_K1, C_K2, C_K3, C_K4, C_K5...C_Kn.

[0074] At this time, one end of the switching elements L_K1, L_K2, L_K3, L_K4, L_K5...L_Kn (specifically pin 4 in the following text) is respectively connected to the transducer driving frequency input terminal COM, and the other end of the switching elements L_K2, L_K3, L_K4, L_K5...L_Kn (specifically pin 3 in the following text) is respectively connected to one end of the matching inductors L2, L3, L4, L5...Ln. The other ends of the matching inductors L2, L3, L4, L5, ... Ln are respectively connected to one end of the switching elements C_K1, C_K2, C_K3, C_K4, C_K5, ... C_Kn (specifically, pin 3 hereinbelow) and one end of the ultrasonic transducer 200. The other ends of the switching elements C_K1, C_K2, C_K3, C_K4, C_K5, ... C_Kn (specifically, pin 4 hereinbelow) are respectively connected to one end of the matching capacitors C2, C3, C4, C5, C6, ... Cn. The other ends of the matching capacitors C2, C3, C4, C5, C6, ... Cn are connected to the other end of the ultrasonic transducer 200 and are commonly grounded. Alternatively, when the driving circuit 300 uses upper and lower tube driving, the other ends of the matching capacitors C2, C3, C4, C5, C6, ... Cn are connected to the other end of the ultrasonic transducer 200 and are commonly connected to the lower tube of the driving circuit 300.

[0075] The inductance values of multiple matching inductors can be different. For example, matching inductor L2 = 1uH, matching inductor L3 = 2.2uH, matching inductor L4 = 3.3uH, matching inductor L5 = 4.7uH, and so on. The capacitance values of multiple matching capacitors can be different. For example, matching capacitor C2 = 100nF, matching inductor C3 = 220nF, matching inductor C4 = 470nF, matching inductor C5 = 680nF, matching inductor C6 = 1uF, and so on.

[0076] It should be noted that, in the embodiment of the present application, the specific scheme for matching the inductor is the same as that described above. Figure 2 The implementation method corresponds to the same, and the specific solution for matching capacitors is the same as the above Figure 3The implementation methods are the same and will not be described here. The difference is that there is no need to set fixed capacitors and fixed inductors. The advantage of the implementation method of the present application is that the matching inductor and matching capacitor can be dynamically selected and adjusted at the same time, the adjustment method is more flexible, and the impedance matching range is wider.

[0077] See also Figures 1 to 4 In some embodiments, each switch element 20 is configured to receive a control signal sent by the control unit 400. The control signal is configured to control the on / off state of the switch element 20.

[0078] Specifically, the number of the switch elements 20 may be one or more. The embodiment of the present application is described by taking the number of the switch elements 20 as an example, and the multiple switch elements 20 are respectively represented as K1, K2, K3, K4, K5...Kn.

[0079] The control unit 400 may be a microcontroller unit (MCU). The control unit 400 may serve as part of the ultrasonic transducer system 500 and is connected to each switching element 20. The control unit 400 includes a plurality of general-purpose input / output (GPIO) pins. GPIO pins are multifunctional interfaces that enable the input and output of digital signals. The control unit 400 may send control signals to each switching element 20 via the plurality of GPIO pins to control the on / off state of each switching element 20.

[0080] like Figures 2 to 4 As shown, the multiple GPIO pins are designated as GPIO1, GPIO2, GPIO3, ..., and GPIOn. Switch element K1 is configured to receive a control signal from GPIO1 of control unit 400 and be turned on or off based on the control signal. Switch element K2 is configured to receive a control signal from GPIO2 of control unit 400 and be turned on or off based on the control signal. Switch element K3 is configured to receive a control signal from GPIO3 of control unit 400 and be turned on or off based on the control signal. Switch element Kn is configured to receive a control signal from GPIOOn of control unit 400 and be turned on or off based on the control signal.

[0081] In the embodiment of the present application, when the control signal sent by the control unit 400 is at a high level, the switch element 20 is turned on; when the control signal sent by the control unit 400 is at a low level, the switch element 20 is turned off. In this way, the control unit 400 can control the corresponding switch element 20 to be turned on and off by outputting high and low levels. Furthermore, by turning each switch element 20 on and off, it is possible to dynamically select whether the impedance matching element 10 is connected to form an LC series resonant circuit. Of course, in other examples, the circuit design can also be such that: when the control signal sent by the control unit 400 is at a low level, the switch element 20 is turned on; when the control signal sent by the control unit 400 is at a high level, the switch element 20 is turned off, and this is not limited here.

[0082] See also Figures 2 to 4 In some embodiments, each switch element 20 includes a first connection terminal, a second connection terminal, a control terminal, and a ground terminal. The first connection terminal is used to connect to the transducer drive frequency input terminal, the second connection terminal is used to connect to the impedance matching element 10, the control terminal is used to receive a control signal, and the ground terminal is used for grounding.

[0083] Specifically, if Figure 2 and Figure 4 As shown, when an impedance matching element 10 is a matching inductor, the first connection terminal of the switch element 20 corresponding to the impedance matching element 10 is pin 4, the second connection terminal is pin 3, the control terminal is pin 1, and the ground terminal is pin 2. In this case, pin 4 is connected to the transducer drive frequency input terminal COM, pin 3 is connected to the matching inductor, pin 1 is connected to the GPIO pin of the control unit 400, and pin 2 is grounded.

[0084] like Figure 3 and Figure 4 As shown, when an impedance matching element 10 is a matching capacitor, the first connection terminal of the switch element 20 corresponding to the impedance matching element 10 is pin 3, the second connection terminal is pin 4, the control terminal is pin 1, and the ground terminal is pin 2. In this case, pin 3 is connected to the transducer drive frequency input terminal COM, pin 4 is connected to the matching capacitor, pin 1 is connected to the GPIO pin of the control unit 400, and pin 2 is grounded.

[0085] For the above two cases, when the control signal received by pin 1 is at a high level, pins 3 and 4 are short-circuited, so that the switching element 20 is turned on; when the control signal received by pin 1 is at a low level, pins 3 and 4 are disconnected, so that the switching element 20 is turned off.

[0086] See also Figures 2 to 4In some embodiments, the impedance matching circuit 100 further includes at least one current limiting resistor 30. Each switching element 20 is connected to the control unit 400 via a corresponding current limiting resistor 30.

[0087] Specifically, if Figures 2 to 4 As shown, the current-limiting resistor 30 is represented by R. The number of current-limiting resistors R can be one or more. The number of current-limiting resistors R is equal to the number of switching elements 20. The control end of each switching element 20 can be connected to the GPIO pin of the control unit 400 through a corresponding current-limiting resistor R. For example, pin 1 of the switching element K1 is connected to the GPIO1 pin of the control unit 400 through the current-limiting resistor R; pin 1 of the switching element K2 is connected to the GPIO2 pin of the control unit 400 through the current-limiting resistor R; pin 1 of the switching element K3 is connected to the GPIO3 pin of the control unit 400 through the current-limiting resistor R... Pin 1 of the switching element Kn is connected to the GPIOn pin of the control unit 400 through the current-limiting resistor R. By providing the current-limiting resistor R, transient high voltage and overcurrent in the impedance matching circuit 100 can be avoided, which may cause damage to the switching element 20, thereby improving the stability of the impedance matching circuit 100.

[0088] See also Figure 5 The ultrasonic self-cleaning device 1000 of the embodiment of the present application includes the ultrasonic transducer system 500 of any of the above embodiments. The ultrasonic self-cleaning device 1000 can use the ultrasonic waves generated by the ultrasonic transducer 200 to clean dirt on the surface of an object, such as water and dust on a lens.

[0089] The ultrasonic self-cleaning device 1000 of the embodiment of the present application can dynamically select the impedance matching element 10 by turning on and off each switching element 20, and can achieve automatic and accurate impedance matching between the impedance matching circuit 100 and the ultrasonic transducer 200 without manual intervention.

[0090] See also Figures 2 to 4 、 Figure 6 The impedance matching method of the embodiment of the present application is applied to the impedance matching circuit 100 of any of the above embodiments. The impedance matching method includes:

[0091] 010: Obtain the frequency point corresponding to the minimum impedance point of the ultrasonic transducer 200;

[0092] 020: Calculating the impedance matching value required in the impedance matching circuit 100 according to the frequency point;

[0093] 030: Controlling the on and off states of the plurality of switch elements 20 according to the impedance matching value, so that the impedance matching circuit 100 and the ultrasonic transducer 200 are impedance matched.

[0094] Specifically, the frequency corresponding to the minimum impedance point of the ultrasonic transducer 200 can be obtained by, for example, detecting the voltage and current data of the ultrasonic transducer 200 in real time, and then determining the frequency corresponding to the minimum impedance point based on the voltage and current data. Alternatively, the drive circuit 300 can be used to perform a frequency sweep, for example, controlling the drive frequency from 1 Hz to 100 kHz, and then obtaining the current variation trends corresponding to these frequency bands to obtain the maximum current point. Based on the maximum current point, the frequency corresponding to the minimum impedance point can be determined.

[0095] After obtaining the frequency point corresponding to the minimum impedance point of the ultrasonic transducer 200, the impedance matching value required in the impedance matching circuit 100 can be calculated based on the frequency point. The on / off states of the multiple switch elements 20 can then be controlled based on the impedance matching value to achieve impedance matching between the impedance matching circuit 100 and the ultrasonic transducer 200. In this way, by controlling the on / off states of the multiple switch elements 20, the impedance matching value in the impedance matching circuit 100 can be quickly switched and selected, achieving automatic and precise impedance matching between the impedance matching circuit 100 and the ultrasonic transducer 200 without manual intervention.

[0096] See also Figure 7 In some embodiments, the impedance matching method further comprises:

[0097] 040: Determine whether the frequency point is offset;

[0098] Calculating the impedance matching value (020) required in the impedance matching circuit 100 according to the frequency point includes:

[0099] 021: When the frequency point shifts, the impedance matching value is calculated based on the frequency point.

[0100] In the embodiments of the present application, when the impedance characteristic point of the ultrasonic transducer 200 changes due to certain factors, including but not limited to changes in ambient temperature, changes in dust in the operating environment, changes in material properties, changes in the installation method, etc., the frequency point corresponding to the minimum impedance characteristic point of the ultrasonic transducer 200 will also shift accordingly. In this case, the impedance matching value is calculated based on the frequency point, and the on-off state of the multiple switching elements 20 is controlled according to the impedance matching value, so that the impedance matching circuit 100 and the ultrasonic transducer 200 are impedance matched, achieving the effect of impedance tuning of the ultrasonic transducer 200, and allowing the ultrasonic transducer system 500 to return to the optimal operating state.

[0101] In addition, when the frequency point shifts, the driving frequency of the driving circuit 300 can be adjusted synchronously to further achieve the impedance tuning effect of the ultrasonic transducer 200.

[0102] In some embodiments, the impedance matching value includes matching inductance value and / or matching capacitance value.

[0103] Specifically, when each impedance matching element 10 is a matching inductor, the impedance matching value can be a matching inductor value; when each impedance matching element 10 is a matching capacitor, the impedance matching value can be a matching capacitor value; when some impedance matching elements 10 are matching inductors and some impedance matching elements 10 are matching capacitors, the impedance matching value can be a matching inductor value and a matching capacitor value.

[0104] The impedance matching circuit 100 and the impedance matching method according to the embodiment of the present application are described below with reference to specific examples.

[0105] Example 1:

[0106] like Figure 2 As shown, the COM terminal is the transducer drive frequency input terminal, C2 is a fixed capacitor, K1, K2, K3, K4, K5...Kn are switch elements 20, and L2, L3, L4, L5...Ln are dynamically selectable matching inductors. Pin 1 of all switch elements 20 is connected to the GPIO pin of the control unit 400 through a current-limiting resistor R. The control unit 400 can control the on and off of the switch elements 20 by outputting high and low level conversion. Pin 3 of each switch element 20 is connected to a matching inductor with a different inductance value. According to the inductance value required for impedance matching, the corresponding switch element 20 can be selected, thereby dynamically selecting whether each matching inductor is connected to achieve the tuning effect of the impedance matching circuit 100; different matching inductors can also be used in parallel combination. By selecting the corresponding switch element 20 combination, automatic and precise adaptation of each inductance value can be achieved.

[0107] If the frequency point corresponding to the minimum impedance point of the original ultrasonic transducer 200 is 31KHz, the resonant frequency of the impedance matching circuit 100 should also be 31KHz. The fixed capacitor C2 in the impedance matching circuit 100 is assumed to be 560nF. Then, the LC resonance calculation formula is: It can be calculated that the required matching inductor value should be 47uH. The control unit 400 only needs to control the GPIO pin to output a high level, and select the switch element 20 in the corresponding 47uH inductor path, while the other switch elements 20 remain closed. At this time, the selected 47uH matching inductor and the 560nF fixed capacitor can form an LC series resonant circuit with a resonant frequency of 31KHz, which matches the 31KHz frequency point of the ultrasonic transducer 200; matching inductors with different inductance values can also be used in parallel combination, according to the inductor parallel formula The final combined matching inductor value is equivalent to 47uH.

[0108] When the frequency point 31KHz corresponding to the minimum impedance point of the original ultrasonic transducer 200 changes, such as when it shifts to 40.3KHz, according to the above-mentioned LC resonance calculation formula, it can be calculated that the required matching inductance value should be 27.8uH. Since 27.8uH is not common among the commonly used inductance values, it can be obtained by combining inductors in parallel. The switch element 20 selects the commonly used inductors of 47uH and 68uH for parallel combination, and the parallel equivalent inductance of the two inductors can be obtained. 27.8uH. At this time, the equivalent inductance of 27.8uH and the fixed capacitor of 560nF form an LC series resonant circuit, and the resonant frequency is 40.3KHz, which matches the frequency point of 40.3KHz after the ultrasonic transducer 200 shifts. In this way, automatic adjustment of impedance matching can be achieved. As mentioned above, the ultrasonic transducer system 500 can accurately calculate the frequency point corresponding to the minimum impedance point based on the voltage data and current data of the ultrasonic transducer 200 obtained in real time, thereby making dynamic adjustments as needed to ensure the stability and reliability of impedance matching.

[0109] Example 2:

[0110] like Figure 3 As shown, the COM terminal is the transducer drive frequency input terminal, L2 is a fixed inductor, K1, K2, K3, K4, K5...Kn are switch elements 20, and C2, C3, C4, C5, C6...Cn are dynamically selectable matching capacitors. The pins of all switch elements 20 are connected to the GPIO pins of the control unit 400 through a current limiting resistor R. The control unit 400 can control the on and off of the switch elements 20 by outputting high and low level conversion. The pin 4 of each switch element 20 is connected to a matching capacitor with different capacitance values. According to the capacitance value required for impedance matching, the corresponding switch element 20 can be selected, thereby dynamically selecting whether each matching capacitor is connected to achieve the tuning effect of the impedance matching circuit 100; different matching capacitors can also be used in parallel combination. By selecting the corresponding switch element 20 combination, automatic and accurate adaptation of each capacitance value can be achieved.

[0111] If the frequency point corresponding to the minimum impedance point of the original ultrasonic transducer 200 is 31KHz, then the resonant frequency of the impedance matching circuit 100 should also be 31KHz. The fixed inductance in the impedance matching circuit 100 is assumed to be 47uH. Then, the LC resonance calculation formula is: It can be calculated that the required matching capacitor value should be 560nF. The control unit 400 only needs to control the GPIO pin to output a high level, and select the switch element 20 in the corresponding 560nF capacitor path, while the other switch elements 20 remain closed. At this time, the selected 560nF matching capacitor and the 47uH fixed inductor can form an LC series resonant circuit with a resonant frequency of 31KHz, which matches the 31KHz frequency point of the ultrasonic transducer 200; matching capacitors with different capacitance values can also be used in parallel combination. According to the capacitor parallel formula C = C1 + C2 + C3 + ... + Cn, the final combined matching capacitor value is equivalent to 560nF.

[0112] When the frequency point 31kHz corresponding to the minimum impedance point of the original ultrasonic transducer 200 changes, such as when it shifts to 40.3kHz, according to the above-mentioned LC resonance calculation formula, it can be calculated that the required matching capacitance value should be 331.8nF. Since 331.8nF is not common among commonly used capacitance values, it can be obtained by combining capacitors in parallel. The switch element 20 selects the common capacitors of 330nF and 1.8nF for parallel combination, and the parallel equivalent capacitance of the two inductors 331.8nF can be obtained. At this time, the equivalent capacitance of 331.8nF and the fixed inductor of 47uH form an LC series resonant circuit with a resonant frequency of 40.3kHz, which matches the frequency point of 40.3kHz after the ultrasonic transducer 200 shifts. In this way, automatic adjustment of impedance matching can be achieved. As mentioned above, the ultrasonic transducer system 500 can accurately calculate the frequency point corresponding to the minimum impedance point based on the voltage data and current data of the ultrasonic transducer 200 obtained in real time, thereby making dynamic adjustments as needed to ensure the stability and reliability of impedance matching.

[0113] Example 3:

[0114] like Figure 4 As shown, the inductor adjustment scheme in the impedance matching circuit 100 is the same as that in the first embodiment, and the capacitor adjustment scheme is the same as that in the second embodiment. The advantage is that the matching inductor and the matching capacitor can be dynamically selected and adjusted at the same time, the adjustment method is more flexible, and the impedance matching range is wider.

[0115] In summary, the impedance matching circuit 100 and the impedance matching method of the embodiment of the present application can realize rapid adjustment and dynamic matching of the parameters of the impedance matching circuit 100, so that the impedance points of the impedance matching circuit 100 and the ultrasonic transducer 200 can be accurately adapted to each other.

[0116] In the impedance matching circuit 100 and the impedance matching method of the embodiment of the present application, when the impedance characteristic point of the ultrasonic transducer 200 shifts, the control unit 400 calculates the impedance matching value required in the impedance matching circuit 100, that is, the matching inductance value and / or the matching capacitance value (as shown in the above calculation formula) according to the frequency point corresponding to the minimum impedance point of the ultrasonic transducer 200 obtained in real time. Wherein, L is the inductance value, unit is H, C is the capacitance value, unit is F). Based on the conduction and cutoff of the switching element 20, the impedance matching value in the impedance matching circuit 100 can be quickly switched and selected, and automatic and accurate impedance matching can be achieved between the impedance matching circuit 100 and the ultrasonic transducer 200 without manual intervention.

[0117] See also Figure 8 and Figure 9 The impedance matching device 2000 according to an embodiment of the present application is applicable to the impedance matching circuit 100 according to any of the above-described embodiments. The impedance matching device 2000 includes an acquisition module 2100, a calculation module 2200, and a control module 2300. The acquisition module 2100 is configured to obtain the frequency corresponding to the minimum impedance point of the ultrasonic transducer 200. The calculation module 2200 is configured to calculate the impedance matching value required by the impedance matching circuit 100 based on the frequency. The control module 2300 is configured to control the on / off states of the plurality of switching elements 20 based on the impedance matching value to achieve impedance matching between the impedance matching circuit 100 and the ultrasonic transducer 200.

[0118] In some embodiments, the impedance matching device 2000 further includes a determination module 2400. The determination module 2400 is configured to determine whether a frequency point has shifted. The calculation module 2200 is specifically configured to calculate an impedance matching value based on a frequency point when a frequency point has shifted.

[0119] In some embodiments, the impedance matching value includes matching inductance value and / or matching capacitance value.

[0120] It should be noted that the explanation of the impedance matching method in the aforementioned embodiment is also applicable to the impedance matching device 2000 in the embodiment of the present application, and will not be elaborated here.

[0121] See also Figure 10 The impedance matching system 3000 of the embodiment of the present application includes one or more processors 3100 and a memory 3200, wherein the memory 3200 stores a computer program. When the computer program is executed by the processor 3100, the impedance matching method of any of the above embodiments is implemented.

[0122] For example, when the computer program is executed by the processor 3100, the following impedance matching method is implemented:

[0123] 010: Obtain the frequency point corresponding to the minimum impedance point of the ultrasonic transducer 200;

[0124] 020: Calculating the impedance matching value required in the impedance matching circuit 100 according to the frequency point;

[0125] 030: Controlling the on and off states of the plurality of switch elements 20 according to the impedance matching value, so that the impedance matching circuit 100 and the ultrasonic transducer 200 are impedance matched.

[0126] For another example, when the computer program is executed by the processor 3100, the following impedance matching method is implemented:

[0127] 040: Determine whether the frequency point is offset;

[0128] 021: When the frequency point shifts, the impedance matching value is calculated based on the frequency point.

[0129] It should be noted that the explanation of the impedance matching method in the aforementioned embodiment is also applicable to the impedance matching system 3000 of the embodiment of the present application, and will not be further described here.

[0130] See also Figure 11 The computer-readable storage medium 4000 of the embodiment of the present application stores a computer program 4100. When the program is executed by the processor 4200, the impedance matching method of any of the above embodiments is implemented.

[0131] For example, when the program is executed by the processor 4200, the following impedance matching method is implemented:

[0132] 010: Obtain the frequency point corresponding to the minimum impedance point of the ultrasonic transducer 200;

[0133] 020: Calculating the impedance matching value required in the impedance matching circuit 100 according to the frequency point;

[0134] 030: Controlling the on and off states of the plurality of switch elements 20 according to the impedance matching value, so that the impedance matching circuit 100 and the ultrasonic transducer 200 are impedance matched.

[0135] For another example, when the program is executed by the processor 4200, the following impedance matching method is implemented:

[0136] 040: Determine whether the frequency point is offset;

[0137] 021: When the frequency point shifts, the impedance matching value is calculated based on the frequency point.

[0138] It should be noted that the explanation of the impedance matching method in the aforementioned embodiment is also applicable to the computer-readable storage medium 4000 in the embodiment of the present application, and will not be elaborated here.

[0139] In summary, the impedance matching circuit 100, ultrasonic transducer system 500, ultrasonic self-cleaning device 1000, impedance matching method, impedance matching device 2000, impedance matching system 3000 and computer-readable storage medium 4000 of the embodiments of the present application can dynamically select the impedance matching element 10 by turning on and off each switching element 20, and can achieve automatic and accurate impedance matching between the impedance matching circuit 100 and the ultrasonic transducer 200 without manual intervention.

[0140] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0141] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0142] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or the interaction between two components. A person of ordinary skill in the art will be able to understand the specific meanings of the above terms in this application based on the specific circumstances.

[0143] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0144] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable storage medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a computer-readable storage medium can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable storage media include the following: an electrical connection having one or more wires (electronic devices), a portable computer disk cartridge (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable storage medium may even be paper or other suitable medium on which the program is printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner as necessary, and then stored in a computer memory.

[0145] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0146] Those skilled in the art will appreciate that all or part of the steps carried out in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment. In addition, the various functional units in the various embodiments of the present application can be integrated into a processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The above-mentioned integrated module can be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. The storage medium mentioned above can be a read-only memory, a disk or an optical disk, etc.

[0147] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are illustrative and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. An impedance matching circuit, characterized in that: It includes at least one impedance matching element and at least one switching element. Each impedance matching element and a corresponding switching element are connected between the transducer driving frequency input terminal and the ultrasonic transducer. Each switching element is used to be turned on or off so that the impedance matching circuit matches the impedance of the ultrasonic transducer.

2. The impedance matching circuit according to claim 1, wherein: Each of the impedance matching elements is a matching inductor, and the impedance matching circuit further includes a fixed capacitor connected to the ultrasonic transducer.

3. The impedance matching circuit according to claim 1, wherein: Each of the impedance matching elements is a matching capacitor, and the impedance matching circuit further includes a fixed inductor connected to the ultrasonic transducer.

4. The impedance matching circuit according to claim 1, wherein: There are multiple impedance matching elements, some of which are matching inductors, and some of which are matching capacitors.

5. The impedance matching circuit according to any one of claims 1 to 4, characterized in that: Each of the switch elements is used to receive a control signal sent by a control unit, and the control signal is used to control the on / off state of the switch element.

6. The impedance matching circuit according to claim 5, wherein: Each of the switching elements includes a first connection end, a second connection end, a control end and a ground end. The first connection end is used to connect to the transducer driving frequency input end, the second connection end is used to connect to the impedance matching element, the control end is used to receive the control signal, and the ground end is used for grounding.

7. The impedance matching circuit according to claim 5, wherein: The impedance matching circuit further includes at least one current-limiting resistor, and each of the switching elements is connected to the control unit via a corresponding current-limiting resistor.

8. An ultrasonic transducer system, characterized in that: include: Ultrasonic transducer; and The impedance matching circuit according to any one of claims 1 to 7, wherein the impedance matching circuit is used for impedance matching with the ultrasonic transducer.

9. The ultrasonic transducer system according to claim 8, characterized in that The ultrasonic transducer system further includes a driving circuit, which is used to provide a driving frequency signal for the ultrasonic transducer.

10. An ultrasonic self-cleaning device, characterized in that: Comprising the ultrasonic transducer system according to claim 8 or 9.

11. An impedance matching method, characterized in that: Applied to the impedance matching circuit according to any one of claims 1 to 7, the impedance matching method comprises: Obtain the frequency point corresponding to the minimum impedance point of the ultrasonic transducer; Calculating the impedance matching value required in the impedance matching circuit according to the frequency point; The on-off states of the plurality of switch elements are controlled according to the impedance matching value, so that the impedance matching circuit matches the impedance of the ultrasonic transducer.

12. The impedance matching method according to claim 11, wherein: The impedance matching method further includes: Determining whether the frequency point is offset; The calculating the impedance matching value required in the impedance matching circuit according to the frequency point includes: When the frequency point shifts, the impedance matching value is calculated according to the frequency point.

13. The impedance matching method according to claim 11, wherein: The impedance matching value includes a matching inductance value and / or a matching capacitance value.

14. An impedance matching device, characterized in that: Applicable to the impedance matching circuit according to any one of claims 1 to 7, wherein the impedance matching device comprises: An acquisition module, used to obtain the frequency point corresponding to the minimum impedance point of the ultrasonic transducer; A calculation module, configured to calculate an impedance matching value required in the impedance matching circuit according to the frequency point; A control module is used to control the on-off states of the plurality of switch elements according to the impedance matching value, so that the impedance matching circuit matches the impedance of the ultrasonic transducer.

15. An impedance matching system, characterized in that: The impedance matching system includes one or more processors and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, the impedance matching method according to any one of claims 11 to 13 is implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the impedance matching method according to any one of claims 11 to 13 is implemented.

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