Reconfigurable L-shaped dynamic impedance matching network system of ultrasonic transducer

Abstract

The invention discloses a reconfigurable L-shaped dynamic impedance matching network system of an ultrasonic transducer, which realizes real-time optimization of power transmission efficiency by adjusting impedance matching parameters and structures in real time. According to the invention, by adjusting the inductor and capacitor combination and the connection mode in the matching circuit, the load change of the ultrasonic transducer can be responded in real time, the load capacity of the driver is adapted, and the driver is ensured to stably operate within a proper load range. Besides, by dynamically adjusting impedance, the power transmission efficiency of the system can be improved, and equipment failure or performance reduction caused by load mismatching can be effectively prevented, so that high efficiency and stability in applications such as ultrasonic treatment and the like are ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of impedance matching of ultrasonic transducers, and particularly relates to a reconfigurable L-type dynamic impedance matching network system for an ultrasonic transducer. Background Art

[0002] The impedance matching of an ultrasonic transducer is crucial for ensuring the efficient operation of an ultrasonic system. The ultrasonic transducer converts electrical energy into mechanical energy for ultrasonic therapy or other applications, and its working efficiency is closely related to the electrical terminal impedance of the transducer. Generally, the electrical terminal impedance of an ultrasonic transducer has an obvious capacitive characteristic at the resonant frequency; in the driving of the ultrasonic transducer, an impedance matching network circuit is required to adjust the impedance of the ultrasonic transducer, so as to adapt to the load capacity of the driver and ensure the normal operation of the system. When the impedance of the transducer is too low, direct driving may cause excessive current, exceeding the load capacity of the driver, and easily lead to overload and damage to the driver; when the impedance of the transducer is too high, the driver cannot provide sufficient current output, resulting in insufficient system power and inability to work properly.

[0003] The impedance characteristic of an ultrasonic transducer fluctuates dynamically with the change of the working state, so how to maintain stable and efficient impedance matching becomes the key. On the other hand, in special situations, the electrical terminal impedance of the ultrasonic transducer is also purposefully changed in real time to meet the performance requirements. However, the existing static impedance matching methods cannot respond to these dynamic changes in real time, resulting in a decrease in system efficiency, and may even cause driver overload or insufficient power, affecting the performance and stability of ultrasonic equipment.

[0004] Through the retrieval of the existing technology, it is found that at the present stage, similar automatic impedance matching methods for ultrasonic transducers have emerged. For example, the Chinese patent application with the publication number CN109596891A provides an on-line impedance measurement and dynamic matching system for an ultrasonic transducer, the Chinese patent application with the publication number CN113533854A provides an on-line impedance measurement and dynamic matching device for an ultrasonic transducer, and the Chinese patent application with the publication number CN106357149A provides an ultrasonic circuit driver with automatic impedance matching and its automatic dynamic matching method. These existing automatic impedance matching systems usually rely on a fixed L-type matching network structure, and can only dynamically adjust the inductance value and capacitance value under a single network configuration, and cannot switch the matching network type according to different working conditions. In other words, they cannot flexibly switch between different types of L-type impedance matching networks (such as the L-type for increasing the load impedance or the L-type for decreasing the load impedance), and cannot adapt to more complex and variable impedance matching requirements.

[0005] In summary, in the field of ultrasonic therapy equipment and related areas, the impedance matching of ultrasonic transducers is crucial for ensuring the efficient and stable operation of the system. Existing impedance matching methods usually rely on static matching networks or simple automatic matching systems, and these methods have the following technical problems in practical applications: 1. Limited load capacity of the driver. When the impedance of the transducer is low, the driver may be subjected to excessive current load, leading to an overload risk; when the impedance is high, the driver cannot provide sufficient current output, resulting in insufficient power; therefore, according to the load-carrying capacity of the driver, an impedance matching network is used to adjust the load impedance of the ultrasonic transducer to an appropriate value.

[0006] 2. Inability to adapt to dynamic load changes. During the operation of the ultrasonic transducer, due to factors such as the environmental medium, temperature change, and working frequency shift, the impedance characteristics will change dynamically; traditional static matching methods cannot respond to these changes in real time, resulting in a decrease in power transmission efficiency and even potential problems such as driver overload or insufficient transducer power.

[0007] 3. Single adjustment of the matching network. Most existing automatic impedance matching methods are limited to fixed L-type matching networks and can only adjust inductors and capacitors under specific circuit topologies, and cannot flexibly switch between different types of L-type matching networks. This limitation makes it difficult for the system to cope with complex working conditions and diverse impedance matching requirements. Summary of the Invention

[0008] In view of the above, the present invention provides a reconfigurable L-type dynamic impedance matching network system for ultrasonic transducers, which can adapt to the dynamic changes of the transducer impedance in real time, improve the power transmission efficiency, ensure the stable operation of the driver under different working conditions, and effectively avoid the risks of overload or insufficient power.

[0009] A reconfigurable L-type dynamic impedance matching network system for ultrasonic transducers is provided between the driver and the ultrasonic transducer, and includes a real-time impedance measurement module, a matching network switching module, and a dynamic adjustment control module. The real-time impedance measurement module is used to collect the voltage and current signals at the output end of the driver in real time, so as to calculate the equivalent load impedance value of the ultrasonic transducer; the dynamic adjustment control module controls the matching network switching module according to the difference between the equivalent load impedance value and the target impedance value, dynamically adjusts the combination state of the inductor and capacitor therein, and then changes the topological structure of the impedance matching network to achieve impedance matching.

[0010] Further, the real-time impedance measurement module includes: A voltage measurement module for measuring and collecting the voltage signal at the output end of the driver; A current measurement module for measuring and collecting the current signal at the output end of the driver; A synchronous analog-to-digital conversion module for converting the collected voltage signal and current signal from analog to digital; An impedance calculation unit extracts the frequency components of the voltage signal and current signal at a specific frequency ω, denoted as U and I respectively, from the digitized voltage signal and current signal through discrete Fourier transform, and then calculates the equivalent load impedance value Z of the ultrasonic transducer.

[0011] Further, the impedance calculation unit calculates the equivalent load impedance value Z of the ultrasonic transducer through the following formula;

[0012] where: |U(ω)| and φ U(ω) are the amplitude and phase of U respectively, |I(ω)| and φ I(ω) are the amplitude and phase of I respectively, j is the imaginary unit, e is the natural constant, and ω is the operating frequency of the ultrasonic transducer.

[0013] Further, the matching network switching module adopts a reconfigurable L-type impedance matching network, which includes an inductor array, a capacitor array, and four single-pole double-throw switches S1~S4. One end of S1 is connected to the positive or negative output terminal of the driver, the other end of S1 is connected to one end of the inductor array, one end of S2 is connected to the positive or negative output terminal of the driver, the other end of S2 is connected to one end of the capacitor array, the other end of the inductor array is connected to one end of S3, the other end of S3 is connected to the positive or negative input terminal of the ultrasonic transducer, the other end of the capacitor array is connected to one end of S4, and the other end of S4 is connected to the positive or negative input terminal of the ultrasonic transducer; the negative output terminal of the driver is short-circuited and connected to the negative input terminal of the ultrasonic transducer.

[0014] Further, the inductor array is composed of multiple inductors connected in series, and each inductor is individually connected in parallel with a single-pole single-throw switch. The inductance values of these inductors increase step by step exponentially; the capacitor array is composed of multiple capacitors connected in parallel, and each capacitor is individually connected in series with a single-pole single-throw switch. The capacitance values of these capacitors increase step by step exponentially.

[0015] Further, when S1 is connected to the positive output terminal of the driver, S2 is connected to the negative output terminal of the driver, and S3 and S4 are connected to the positive input terminal of the ultrasonic transducer, the L-type impedance matching network is a low-pass impedance-reducing type at this time; when S1 and S2 are connected to the positive output terminal of the driver, S3 is connected to the positive input terminal of the ultrasonic transducer, and S4 is connected to the negative input terminal of the ultrasonic transducer, the L-type impedance matching network is a low-pass impedance-increasing type at this time; when S1 is connected to the negative output terminal of the driver, S2 is connected to the positive output terminal of the driver, and S3 and S4 are connected to the positive input terminal of the ultrasonic transducer, the L-type impedance matching network is a high-pass impedance-reducing type at this time; when S1 and S2 are connected to the positive output terminal of the driver, S3 is connected to the negative input terminal of the ultrasonic transducer, and S4 is connected to the positive input terminal of the ultrasonic transducer, the L-type impedance matching network is a high-pass impedance-increasing type at this time.

[0016] Further, the specific control process of the dynamic adjustment control module is as follows: (1) Control S1 to be connected to the positive output terminal of the driver, S2 to be connected to the negative output terminal of the driver, S3 to be connected to the positive input terminal of the ultrasonic transducer, and S4 to be connected to the negative input terminal of the ultrasonic transducer. Control the switches in the inductor array to make the inductance value of the inductor array 0. At this time, measure the equivalent load impedance value Z of the ultrasonic transducer through the real-time impedance measurement module as the initial impedance value; (2) According to the initial impedance value, the target impedance value provided externally, and the high-pass and low-pass requirements, determine the type of the L-type impedance matching network, and then control the switches in the inductor array and the capacitor array to make the L-type impedance matching network form a topological structure of the corresponding type; (3) According to the initial impedance value, the target impedance value, and the type of the L-type impedance matching network, calculate the inductance value of the inductor array and the capacitance value of the capacitor array, and use them as the theoretical values; (4) Control the switches in the inductor array and the capacitor array to switch the inductor array and the capacitor array into a combined structure closest to the theoretical value; (5) Re-measure the equivalent load impedance value Z of the ultrasonic transducer through the real-time impedance measurement module as the actual impedance value; (6) According to the actual impedance value, the target impedance value, and the type of the L-type impedance matching network, calculate the inductance value of the inductor array and the capacitance value of the capacitor array, and use them as the effective values; Take the difference between the theoretical value and the effective value as the adjustment amount of the inductor array and the capacitor array; (7) Determine whether the adjustment amount is less than the minimum step value: If so, execute step (8); if not, execute step (4) to continue the adjustment and optimization; (8) Determine whether there is a real-time matching requirement: If so, execute step (5); if not, execute step (9); (9) The matching is completed, and the structural form of the current L-type impedance matching network is maintained.

[0017] Further, the criteria for determining the type of the L-type impedance matching network in step (2) are as follows: When R ≤ Z r and the external requirement is high-pass, the L-type impedance matching network is a high-pass impedance-reducing type; When R ≤ Z r and the external requirement is low-pass, the L-type impedance matching network is a low-pass impedance-reducing type; When , Z i ≥ 0 and the external requirement is high-pass, the L-type impedance matching network is a high-pass impedance-increasing type; When , Z i ≥ 0 and the external requirement is low-pass, the L-type impedance matching network is a low-pass impedance-reducing type; When , Z i <0 and the external requirement is high-pass, the L-type impedance matching network is a high-pass impedance-reducing type; When , Z i <0 and the external requirement is low-pass, the L-type impedance matching network is a low-pass impedance-increasing type; When and the external requirement is high-pass, the L-type impedance matching network is a high-pass impedance-increasing type; When and the external requirement is low-pass, the L-type impedance matching network is a low-pass impedance-increasing type; Where: R is the target impedance value, Z r and Z i are the real part and the imaginary part of the equivalent load impedance value Z, respectively.

[0018] Further, in steps (3) and (6), the inductance value of the inductor array and the capacitance value of the capacitor array are calculated by the following formula; If the L-type impedance matching network is a low-pass impedance-reducing type, then: ;

[0019] If the L-type impedance matching network is a high-pass impedance-reducing type, then: ;

[0020] If the L-type impedance matching network is a low-pass impedance-increasing type, then: ;

[0021] If the L-type impedance matching network is a high-pass impedance-increasing type, then: ;

[0022] where: L and C are the inductance value of the inductor array and the capacitance value of the capacitor array respectively, ω is the operating frequency of the ultrasonic transducer, R is the target impedance value, Z r and Z i are the real part and the imaginary part of the equivalent load impedance value Z respectively, and Y r and Y i are the real part and the imaginary part of the admittance value corresponding to the equivalent load impedance value Z respectively.

[0023] Based on the above technical solutions, the present invention has the following beneficial technical effects: 1. Simplify the circuit structure and reduce the number of components. By using an inductor array and a capacitor array in combination, the present invention can ingeniously implement four different L-type impedance matching networks without using multiple independent matching components; this method greatly simplifies the circuit design, reduces the number of components required in the system, and lowers the cost and complexity.

[0024] 2. Improve the matching flexibility. Under different ultrasonic transducers, operating frequencies, and load conditions, the type of the optimal impedance matching network required by the system may be different; by providing four switchable L-type matching networks, the present invention can flexibly adapt to different impedance characteristics, ensuring that a suitable matching scheme can be found in various working environments to optimize power transmission.

[0025] 3. Reduce power reflection and reactive power consumption. By matching the load equivalent impedance to a purely resistive impedance, the present invention reduces the power reflection and reactive power consumption caused by impedance mismatch, which can reduce the reflected power and heat generation between the transducer and the driver and avoid the degradation of system performance.

[0026] 4. Adapt to complex working conditions. The present invention can adjust dynamically in real time to adapt to the impedance changes of the ultrasonic transducer under different loads and working environments; compared with the traditional static matching method, the dynamic adjustment ability of the present invention can cope with different working conditions and ensure good matching effects under complex and dynamic working conditions.

[0027] 5. Improve the driver efficiency and system stability. The dynamic adjustment matching network method of the present invention can effectively adjust the equivalent impedance of the ultrasonic transducer to optimize the matching between the driver and the load; when the impedance of the ultrasonic transducer is too low, the present invention increases the impedance of the matching network to reduce the current load of the driver and avoid damage or instability of the driver caused by overload; when the impedance of the transducer is too high, the present invention reduces the impedance of the matching network to ensure that the driver can provide sufficient current and power and avoid the problem of reduced drive efficiency caused by too light a load; this dynamic matching mechanism effectively improves the overall working efficiency of the driver and the stability of the system, ensuring efficient drive under different load conditions.

[0028] In summary, the present invention can not only adjust the inductance and capacitance values under the same matching network, but also switch between different L-type network configurations. This flexibility enables the system to dynamically adjust the matching network structure according to the real-time working conditions to meet a wider range of load change requirements, thereby ensuring that the driver can work stably and efficiently under various conditions; this innovation effectively makes up for the deficiencies of the prior art and significantly improves the adaptability and performance of ultrasonic devices in practical applications. Brief Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of the reconfigurable L-type dynamic impedance matching network circuit of the ultrasonic transducer of the present invention.

[0030] Figure 2 It is a schematic diagram of four L-type impedance matching networks of the matching network switching module and their equivalent structures.

[0031] Figure 3 It is a schematic structural diagram of the inductor array.

[0032] Figure 4 It is a schematic structural diagram of the capacitor array.

[0033] Figure 5 It is a schematic diagram of the control work flow of the dynamic adjustment control module. Detailed Embodiments

[0034] In order to describe the present invention more specifically, the technical solutions of the present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0035] As Figure 1 shown, this embodiment provides a reconfigurable L-type dynamic impedance matching network system for an ultrasonic transducer, which is inserted between the driver and the ultrasonic transducer to improve the power transmission efficiency; this circuit system mainly includes a real-time impedance measurement module 1, a matching network switching module 2, and a dynamic adjustment control module 3, where: The real-time impedance measurement module 1 includes a voltage measurement module 11, a current measurement module 12, a synchronous analog-to-digital conversion module 13, and an impedance calculation unit 14, which can complete impedance measurement during the continuous output of the driver without cutting off the excitation signal. The voltage measurement circuit 11 monitors the voltage difference between the positive and negative lines at the output end of the driver in real time. Since the voltage difference between the positive and negative lines is generally large, a resistor voltage divider is used and then an operational amplifier buffer is connected. Then, a differential amplifier is used to adjust the signal to a magnitude suitable for the input range of the synchronous analog-to-digital conversion module 13. The current measurement module 12 is on the negative line. A current transformer is used, and then a load resistor is used to convert the secondary current on the current transformer into a magnitude suitable for the input range of the synchronous analog-to-digital conversion module 13. The current measurement module 12 can also use a precision resistor with a low resistance value and high precision in series, and the voltage difference of the precision resistor is amplified by a differential amplifier to a magnitude suitable for the input range of the synchronous analog-to-digital conversion module 13. The synchronous analog-to-digital conversion module 13 synchronously samples the voltage signal and the current signal and then sends them to the impedance calculation unit 14; to ensure accuracy, the sampling frequency needs to reach more than 20 times the ultrasonic working frequency. The impedance calculation unit 14 uses the discrete Fourier transform (DFT) to accurately separate specific frequency components, calculates the amplitudes and phase differences of the voltage and current at the ultrasonic working frequency, and calculates the equivalent load impedance value of the ultrasonic transducer at the working frequency according to the collected voltage and current amplitudes and their phase differences. The formula is ; The impedance value Z obtained by real-time measurement can be expressed in the form of the sum of the real part and the imaginary part, that is, Z = Z r + jZ i , and its corresponding admittance can also be expressed in the form of the sum of the real part and the imaginary part, that is, Y = Y r + jY i . The entire measurement process is synchronized with the operation of the driver, and impedance monitoring can be completed without interrupting the drive signal.

[0036] The matching network switching module 2 consists of a reconfigurable L-type impedance matching network, including an inductor array 21, a capacitor array 22, and four single-pole double-throw switches 23, 24, 25, 26; by switching the switch positions of the four single-pole double-throw switches 23, 24, 25, 26, four different L-type impedance matching networks can be formed, corresponding to a low-pass impedance reduction type, a low-pass impedance increase type, a high-pass impedance reduction type, and a high-pass impedance increase type, as Figure 2As shown in the figure. The single-pole double-throw switch 23 is connected to the positive wire, the single-pole double-throw switch 24 is connected to the negative wire, the single-pole double-throw switch 25 is connected to the positive wire, and the single-pole double-throw switch 26 is connected to the positive wire, then a low-pass impedance-reducing type matching network is formed; the single-pole double-throw switch 23 is connected to the positive wire, the single-pole double-throw switch 24 is connected to the positive wire, the single-pole double-throw switch 25 is connected to the positive wire, and the single-pole double-throw switch 26 is connected to the negative wire, then a low-pass impedance-increasing type matching network is formed; the single-pole double-throw switch 23 is connected to the negative wire, the single-pole double-throw switch 24 is connected to the positive wire, the single-pole double-throw switch 25 is connected to the positive wire, and the single-pole double-throw switch 26 is connected to the positive wire, then a high-pass impedance-reducing type matching network is formed; the single-pole double-throw switch 23 is connected to the positive wire, the single-pole double-throw switch 24 is connected to the positive wire, the single-pole double-throw switch 25 is connected to the negative wire, and the single-pole double-throw switch 26 is connected to the positive wire, then a low-pass impedance-increasing type matching network is formed; the four single-pole double-throw switches 23, 24, 25, and 26 are constituted by a relay device, and the negative wire of the driver is short-circuited and connected to the negative wire of the ultrasonic transducer.

[0037] The inductor array is composed of N inductors L 1 ~L N connected in series. Each inductor is individually shunted by a single-pole single-throw switch (corresponding to S L1 ~S LN ) for controlling whether the inductor is connected to the series array. As Figure 3 shown. When the single-pole single-throw switch is open, the inductor is normally connected to the series array; when the single-pole single-throw switch is closed, the inductor is short-circuited and not connected to the series array. The inductance value of the inductor array is equal to the sum of the values of the inductors connected to the series array. Therefore, a total of 2 N different combinations can be formed. To ensure the performance of the matching network, magnetic shielded high-frequency power inductors are used for the inductors; in practical applications, the inductance value cannot be any desired value. Commercially available magnetic shielded high-frequency power inductors generally adopt the E series standard values. Therefore, inductors with a nearly exponential step are required. In this embodiment, 11 magnetic shielded high-frequency power inductors are used, and the inductance values are 0.047 uH, 0.1 uH, 0.22 uH, 0.47 uH, 0.82 uH, 1.5 uH, 3.3 uH, 6.8 uH, 10 uH, 22 uH, and 47 uH respectively. The formed inductor array can form 2048 different inductor combinations from 0 to 92.257 uH, and the single-pole single-throw switch is implemented by a relay.

[0038] The capacitor array is composed of N capacitors C 1 ~C N connected in series. Each capacitor is individually connected in series with a single-pole single-throw switch (corresponding to S C1 ~S CN ) for controlling whether the capacitor is connected to the parallel array. As Figure 4As shown. When the single-pole single-throw switch is closed, the capacitor is normally connected to the parallel array; when the single-pole single-throw switch is open, the capacitor is disconnected and not connected to the parallel array. The capacitance value of the capacitor array is equal to the sum of the capacitance values of the capacitors connected to the parallel array. Therefore, a total of 2 N different combinations can be formed. To ensure the performance of the matching network, ceramic capacitors with good frequency characteristics are used for the capacitors; in practical applications, the capacitance value cannot be any desired value. Commercial ceramic capacitors generally adopt the E-series standard values. Therefore, capacitors with a capacitance value close to an exponential step are required. In this embodiment, 11 ceramic capacitors are used, and the capacitance values are 0.047 nF, 0.1 nF, 0.22 nF, 0.47 nF, 0.82 nF, 1.5 nF, 3.3 nF, 6.8 nF, 10 nF, 22 nF, and 47 nF respectively. The formed capacitor array can form 2048 different capacitance combinations from 0 to 92.257 nF. The single-pole single-throw switch is implemented using a relay.

[0039] In practical applications, the impedance is generally matched to a purely resistive impedance. Let this impedance point be R, and let the ultrasonic working angular frequency be ω. The impedance of the ultrasonic transducer Z = Z r + jZ i , and the corresponding admittance Y = Y r + jY i .

[0040] For a low-pass impedance-reducing matching network, the capacitance value to be shunted, and the inductance value to be series-connected. When Z i ≤ 0, the target R can be any value less than or equal to Z r ; when Z i > 0, the target R can be any value less than or equal to .

[0041] For a high-pass impedance-reducing matching network, the inductance value to be shunted, and the capacitance value to be series-connected. When Z i ≥ 0, the target R can be any value less than or equal to Z r ; when Z i < 0, the target R can be any value less than or equal to .

[0042] For a low-pass impedance-increasing matching network, the inductance value L = , and the capacitance value to be shunted. When Z i ≥ 0, the target R can be any value greater than or equal to ; when Z iWhen < 0, the target R can be any value greater than or equal to Z r .

[0043] For a high-pass impedance-improving matching network, the value of the capacitor to be connected in series , and the value of the inductor to be connected in parallel L = . When Z i ≤ 0, the target R can be any value greater than or equal to ; when Z i > 0, the target R can be any value greater than or equal to Z r .

[0044] Therefore, when selecting the type of matching network, Table 1 can be referred to: Table 1

[0045] The dynamic adjustment control module 3 reconstructs and adjusts the matching network switching module 2 according to the impedance value measured by the real-time impedance measurement module 1, so that the load equivalent impedance reaches the target value. List all the on-off state combinations of all the single-pole single-throw switches of the inductor array and the capacitor array, calculate and list the theoretical inductor value and theoretical capacitor value corresponding to each on-off state in a table, and arrange them in the order of value size; in practice, since inductors and capacitors are not ideal components and have various non-ideal characteristics, the inductor value and capacitor value shown during operation deviate from the marked theoretical values. Therefore, during the real-time matching process, it is necessary to gradually adjust the inductor array and the capacitor array to approach the target value, and the specific steps are as Figure 5 shown: S301: Before impedance matching, measure the load impedance. Connect switch 23 and switch 25 to the positive pole, adjust the value of the inductor array to 0, connect switch 24 and switch 26 to the negative pole, and at this time, a mode of directly connecting the driver to the ultrasonic transducer is formed. After starting the driver to give an excitation, use the real-time impedance measurement module 1 to measure and calculate the impedance value and the corresponding admittance value of the ultrasonic transducer.

[0046] S302: According to the target impedance value R, the imaginary part Z i of the initial impedance value, and the requirements of high-pass and low-pass, select the corresponding type of matching network according to the above table, and control the switch positions of the single-pole double-throw switches 23, 24, 25, and 26 to form the corresponding impedance matching network type for the matching network switching module 2.

[0047] S303: According to the target impedance value, the initial impedance value, and the type of matching network, calculate the theoretical capacitor value and theoretical inductor value required for the capacitor array and the inductor array in the matching network switching module 2 according to the formula.

[0048] S304: According to the theoretical capacitance value and the theoretical inductance value, switch the capacitance array and the inductance array to the combination closest to the theoretical values.

[0049] S305: Re - use the real - time impedance measurement module 1 to measure and calculate the equivalent load impedance value and the corresponding admittance value of the current ultrasonic transducer.

[0050] S306: Compare the equivalent load impedance value and the corresponding admittance value of the current ultrasonic transducer with the initial ultrasonic transducer impedance value and the corresponding admittance value. According to the form of the impedance matching network currently in use, calculate the effective capacitance value of the current capacitance array and the effective inductance value of the current inductance array. The capacitance value to be adjusted is the difference between the effective capacitance value of the current capacitance array and the required theoretical capacitance value calculated in S303, and the inductance value to be adjusted is the difference between the effective inductance value of the current inductance array and the required theoretical inductance value calculated in S303.

[0051] S307: Determine whether the capacitance value and the inductance value to be adjusted currently are less than the minimum step value: If so, it is currently impossible to continue adjusting the optimization matching network switching module 2, and go to step S308; otherwise, go to step S304 to continue adjusting and optimizing.

[0052] S308: If there is a real - time matching requirement, return to step S305 to continue monitoring the load impedance value and observe whether it is necessary to adjust the optimization matching network switching module 2; if there is no real - time matching requirement, go to step S309.

[0053] S309: The matching is completed, and the current impedance matching network form is maintained.

[0054] In summary, the core technical points and innovations of the present invention are mainly reflected in the following aspects: 1. The reconfigurable structure of the L - type impedance matching network. The present invention uses an inductance, a capacitance array, and four single - pole double - throw switches to realize the dynamic reconfiguration of four types of L - type matching networks, adapting to different impedance matching requirements; according to the matching target impedance value, the ultrasonic transducer impedance value, and the requirements of high - pass and low - pass, the corresponding appropriate impedance matching network type can be selected.

[0055] 2. The step - by - step dynamic adjustment mechanism of the inductance / capacitance array. In the system of the present invention, the inductance and capacitance arrays adopt an exponential - step adjustment method. Using N exponential - step devices, up to 2 N levels of matching accuracy are achieved, greatly improving the dynamic range, flexibility, and accuracy of impedance matching.

[0056] 3. Calculation method for theoretical values of impedance matching inductors and capacitors. The present invention provides an accurate calculation method for inductors and capacitors based on the load impedance characteristics of ultrasonic transducers and target impedance. According to the operating frequency of the transducer, the actual load impedance, the target impedance, and the type of impedance matching network, using the complex impedance matching formula, considering the imaginary and real parts of the impedance, separating and accurately calculating the values of the inductor and capacitor elements, and calculating the theoretical values of the optimal matching inductor and capacitor.

[0057] 4. Design of real-time impedance measurement module. The present invention realizes high-precision real-time measurement of impedance at the operating frequency of the ultrasonic transducer through synchronous sampling of voltage and current and discrete Fourier transform calculation, avoiding interference from multi-frequency signals; at the same time, the voltage and current sampling do not interfere with the drive output and can be carried out synchronously and in real time with the drive.

[0058] 5. Full-closed-loop dynamic regulation control system. The present invention dynamically adjusts the matching network based on the real-time measured impedance, and adjusts according to the actual effective values of the calculated inductor array and capacitor array, realizing high-speed closed-loop control to ensure that the load impedance and the target impedance maintain the optimal matching state.

[0059] 6. Dynamic adjustment of matching accuracy and tolerance control. When the matching error exceeds the set threshold, the system of the present invention automatically fine-tunes the inductor / capacitor matrix to achieve high-precision matching and ensure that the ultrasonic energy transmission efficiency reaches the optimal state.

[0060] 7. Design of miniaturized, high-Q, and few-component matching network components. The present invention uses low-loss, miniaturized, high-Q commercial inductors and capacitors to reduce the attenuation of the matching network to the signal and ensure the ultrasonic power transmission efficiency. At the same time, the present invention uses exponential step values for permutation and combination, and a small number of components can form an exponential combination number. Therefore, the overall circuit can be designed in a miniaturized manner to adapt to the application scenarios of portable or embedded ultrasonic devices.

[0061] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art to the present invention should be within the protection scope of the present invention according to the disclosure of the present invention.

Claims

1. A reconfigurable L-type dynamic impedance matching network system for an ultrasonic transducer, characterized in that: The system is arranged between the driver and the ultrasonic transducer, and includes a real-time impedance measurement module, a matching network switching module and a dynamic adjustment control module. The real-time impedance measurement module is used to collect voltage and current signals at the output end of the driver in real time, so as to calculate the equivalent load impedance value of the ultrasonic transducer; the dynamic adjustment control module controls the matching network switching module according to the difference between the equivalent load impedance value and the target impedance value, dynamically adjusts the combination state of the inductor and the capacitor therein, thereby changing the topological structure of the impedance matching network to achieve impedance matching.

2. The reconfigurable L-type dynamic impedance matching network system of an ultrasonic transducer according to claim 1, characterized in that: The real-time impedance measurement module comprises: A voltage measurement module is used to measure the voltage signal at the output end of the acquisition driver; A current measurement module is used to measure and collect the current signal at the output end of the driver; A synchronous analog-to-digital conversion module is used to convert the collected voltage and current signals from analog quantities into digital quantities; The impedance calculation unit uses the digitized voltage signal and current signal to extract the frequency components of the voltage signal and the current signal at a specific frequency ω through discrete Fourier transform, which are recorded as U and I respectively, and then calculates the equivalent load impedance value Z of the ultrasonic transducer.

3. The reconfigurable L-type dynamic impedance matching network system of an ultrasonic transducer according to claim 2, characterized in that: The impedance calculation unit calculates the equivalent load impedance value Z of the ultrasonic transducer by the following formula; ; Among them: |U(ω)| and φ U(ω) are the amplitude and phase of U, |I(ω)| and φ I(ω) are the amplitude and phase of I respectively, j is the imaginary unit, e is the natural constant, and ω is the operating frequency of the ultrasonic transducer.

4. The reconfigurable L-type dynamic impedance matching network system of an ultrasonic transducer according to claim 1, characterized in that: The matching network switching module adopts a reconfigurable L-type impedance matching network, which includes an inductor array, a capacitor array and four single-pole double-throw switches S1~S4, wherein one end of S1 is connected to the positive or negative output end of the driver, the other end of S1 is connected to one end of the inductor array, one end of S2 is connected to the positive or negative output end of the driver, the other end of S2 is connected to one end of the capacitor array, the other end of the inductor array is connected to one end of S3, the other end of S3 is connected to the positive or negative input end of the ultrasonic transducer, the other end of the capacitor array is connected to one end of S4, and the other end of S4 is connected to the positive or negative input end of the ultrasonic transducer; the negative output end of the driver is short-circuited with the negative input end of the ultrasonic transducer.

5. The reconfigurable L-shaped dynamic impedance matching network system of an ultrasonic transducer according to claim 4, characterized in that: The inductor array is composed of a plurality of inductors connected in series, each of which is individually connected in parallel with a single-pole single-throw switch, and the inductance values ​​of these inductors are successively stepped exponentially; the capacitor array is composed of a plurality of capacitors connected in parallel, each of which is individually connected in series with a single-pole single-throw switch, and the capacitance values ​​of these capacitors are successively stepped exponentially.

6. The reconfigurable L-type dynamic impedance matching network system of an ultrasonic transducer according to claim 5, characterized in that: When S1 is connected to the positive output terminal of the driver, S2 is connected to the negative output terminal of the driver, and S3 and S4 are connected to the positive input terminal of the ultrasonic transducer, the L-type impedance matching network is a low-pass impedance reduction type; when S1 and S2 are connected to the positive output terminal of the driver, S3 is connected to the positive input terminal of the ultrasonic transducer, and S4 is connected to the negative input terminal of the ultrasonic transducer, the L-type impedance matching network is a low-pass impedance increase type; when S1 is connected to the negative output terminal of the driver, S2 is connected to the positive output terminal of the driver, and S3 and S4 are connected to the positive input terminal of the ultrasonic transducer, the L-type impedance matching network is a high-pass impedance reduction type; when S1 and S2 are connected to the positive output terminal of the driver, S3 is connected to the negative input terminal of the ultrasonic transducer, and S4 is connected to the positive input terminal of the ultrasonic transducer, the L-type impedance matching network is a high-pass impedance increase type.

7. The reconfigurable L-type dynamic impedance matching network system of an ultrasonic transducer according to claim 6, characterized in that: The specific control process of the dynamic adjustment control module is as follows: (1) Control S1 to connect to the positive output terminal of the driver, S2 to connect to the negative output terminal of the driver, S3 to connect to the positive input terminal of the ultrasonic transducer, S4 to connect to the negative input terminal of the ultrasonic transducer, and control the switches in the inductor array to make the inductance value of the inductor array 0. At this time, the equivalent load impedance value Z of the ultrasonic transducer is calculated by the real-time impedance measurement module as the initial impedance value; (2) Determine the type of the L-type impedance matching network based on the initial impedance value and the target impedance value and high-pass and low-pass requirements provided externally, and then control the switches in the inductor array and the capacitor array so that the L-type impedance matching network forms a corresponding type of topological structure; (3) According to the initial impedance value, the target impedance value and the type of the L-type impedance matching network, the inductance value of the inductor array and the capacitance value of the capacitor array are calculated and used as theoretical values; (4) Controlling switches in the inductor array and the capacitor array to switch the inductor array and the capacitor array to a combination structure closest to the theoretical value; (5) Re-using the real-time impedance measurement module to calculate the equivalent load impedance value Z of the ultrasonic transducer as the actual impedance value; (6) According to the actual impedance value, the target impedance value and the type of the L-type impedance matching network, the inductance value of the inductor array and the capacitance value of the capacitor array are calculated and used as the effective value; the difference between the theoretical value and the effective value is used as the adjustment amount of the inductor array and the capacitor array; (7) Determine whether the adjustment amount is less than the minimum step value: if so, execute step (8); if not, execute step (4) to continue the adjustment optimization; (8) Determine whether there is a real-time matching requirement: if so, execute step (5); if not, execute step (9); (9) The matching is completed and the current structural form of the L-type impedance matching network is maintained.

8. The reconfigurable L-shaped dynamic impedance matching network system of an ultrasonic transducer according to claim 7, characterized in that: The criteria for determining the type of L-type impedance matching network in step (2) are as follows: When R≤Z r And when high-pass is required externally, the L-type impedance matching network is a high-pass impedance reduction type; When R≤Z r And when low-pass is required externally, the L-type impedance matching network is a low-pass impedance reduction type; when , Z i ≥0 and when high-pass is required externally, the L-type impedance matching network is a high-pass impedance-enhancing type; when , Z i ≥0 and when low-pass is required externally, the L-type impedance matching network is a low-pass impedance reduction type; when , Z i When <0 and high pass is required externally, the L-type impedance matching network is a high pass impedance reduction type; when , Z i When <0 and low-pass is required externally, the L-type impedance matching network is a low-pass impedance-enhancing type; when And when high-pass is required externally, the L-type impedance matching network increases the impedance type for high-pass; when And when low-pass is required externally, the L-type impedance matching network is a low-pass impedance-enhancing type; Where: R is the target impedance value, Z r and Z i are the real and imaginary parts of the equivalent load impedance value Z respectively.

9. The reconfigurable L-shaped dynamic impedance matching network system of an ultrasonic transducer according to claim 7, characterized in that: In the steps (3) and (6), the inductance value of the inductor array and the capacitance value of the capacitor array are calculated by the following formulas; If the L-type impedance matching network is a low-pass impedance reduction type, then: ； ; If the L-type impedance matching network is a high-pass impedance reduction type, then: ； ; If the L-type impedance matching network is a low-pass impedance-raising type, then: ； ; If the L-type impedance matching network is a high-pass impedance-raising type, then: ； ; Where: L and C are the inductance of the inductor array and the capacitance of the capacitor array, ω is the operating frequency of the ultrasonic transducer, R is the target impedance value, Z r and Z i are the real and imaginary parts of the equivalent load impedance Z, Y r and Y i They are the real and imaginary parts of the admittance value corresponding to the equivalent load impedance value Z respectively.

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