A reconfigurable L-shaped dynamic impedance matching network system for ultrasonic transducers

Abstract

The present invention discloses a reconfigurable L-shaped dynamic impedance matching network system for an ultrasonic transducer. This system optimizes power transmission efficiency in real time by adjusting the impedance matching parameters and structure in real time. By adjusting the inductor and capacitor combination and connection method in the matching circuit, the system can respond to changes in the ultrasonic transducer load in real time, adapting the driver's load capacity to ensure stable operation within an appropriate load range. Furthermore, by dynamically adjusting the impedance, the system not only improves the system's power transmission efficiency but also effectively prevents equipment failure or performance degradation caused by load mismatch, thereby ensuring high efficiency and stability in applications such as ultrasonic therapy.

Description

Technical Field

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

[0002] Impedance matching of ultrasonic transducers is crucial to ensuring the efficient operation of ultrasonic systems. Ultrasonic transducers convert electrical energy into mechanical energy for ultrasonic therapy or other applications, and their operating efficiency is closely related to the electrical impedance of the transducer. Typically, the electrical impedance of an ultrasonic transducer has a significant capacitive characteristic at the resonant frequency. When driving an ultrasonic transducer, an impedance matching network circuit is required to adjust the impedance of the ultrasonic transducer 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 result in excessive current, exceeding the load capacity of the driver, easily causing 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 failure to operate normally.

[0003] The impedance characteristics of ultrasonic transducers fluctuate dynamically with changes in operating conditions, making stable and efficient impedance matching crucial. Furthermore, in special scenarios, the electrical impedance of the ultrasonic transducer may need to be purposefully altered in real time to meet performance requirements. However, existing static impedance matching methods are unable to address these dynamic changes in real time, resulting in reduced system efficiency and potentially even driver overload or power shortages, impacting the performance and stability of the ultrasonic device.

[0004] Through searching the prior art, it is found that similar automatic impedance matching methods for ultrasonic transducers have appeared at this stage. For example, the Chinese patent application with publication number CN109596891A provides an online impedance measurement and dynamic matching system for an ultrasonic transducer, the Chinese patent application with publication number CN113533854A provides an online impedance measurement and dynamic matching device for an ultrasonic transducer, and the Chinese patent application with publication number CN106357149A provides an automatic impedance matching ultrasonic circuit driver 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 and capacitance values ​​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 increasing the load impedance L-type or reducing the load impedance L-type), and cannot adapt to more complex and variable impedance matching requirements.

[0005] In summary, in ultrasonic therapy equipment and related fields, impedance matching of ultrasonic transducers is crucial to ensure efficient and stable operation of the system. Existing impedance matching methods are usually based on static matching networks or simple automatic matching systems. These methods have the following technical problems in practical applications:

[0006] 1. Limited driver load capacity. When the transducer impedance is low, the driver may bear excessive current load, resulting in overload risk. When the impedance is high, the driver cannot provide sufficient current output, resulting in insufficient power. Therefore, an impedance matching network is required to adjust the ultrasonic transducer load impedance to the appropriate level based on the driver's load capacity.

[0007] 2. Unable to adapt to dynamic load changes. During operation, the impedance characteristics of ultrasonic transducers undergo dynamic changes due to factors such as the ambient medium, temperature changes, and operating frequency offsets. Traditional static matching methods cannot respond to these changes in real time, resulting in reduced power transmission efficiency and even potentially causing problems such as driver overload or transducer power shortage.

[0008] 3. Single matching network adjustment. Existing automatic impedance matching methods are mostly limited to fixed L-type matching networks. They can only adjust inductance and capacitance within 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

[0009] In view of the above, the present invention provides a reconfigurable L-shaped dynamic impedance matching network system for an ultrasonic transducer, 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 risk of overload or insufficient power.

[0010] A reconfigurable L-shaped dynamic impedance matching network system for an ultrasonic transducer is arranged between a 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 driver output end in real time, thereby calculating the equivalent load impedance value of the ultrasonic transducer; the dynamic adjustment control module controls the matching network switching module based on 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 thereby changes the topology of the impedance matching network to achieve impedance matching.

[0011] Furthermore, the real-time impedance measurement module includes:

[0012] The voltage measurement module is used to measure and acquire the voltage signal at the output end of the driver;

[0013] The current measurement module is used to measure and collect the current signal at the output end of the driver;

[0014] A synchronous analog-to-digital conversion module is used to convert the collected voltage and current signals from analog to digital quantities;

[0015] The impedance calculation unit uses the digitized voltage signal and current signal to extract the frequency components of the voltage signal and 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.

[0016] Furthermore, the impedance calculation unit calculates the equivalent load impedance value Z of the ultrasonic transducer by the following formula:

[0017]

[0018] Where: |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 a natural constant, and ω is the operating frequency of the ultrasonic transducer.

[0019] Furthermore, 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.

[0020] Furthermore, the inductor array is composed of multiple inductors connected in series, each inductor is individually connected in parallel with a single-pole single-throw switch, and the inductance values ​​of these inductors are exponentially stepped in sequence; the capacitor array is composed of multiple capacitors connected in parallel, each capacitor is individually connected in series with a single-pole single-throw switch, and the capacitance values ​​of these capacitors are exponentially stepped in sequence.

[0021] Furthermore, 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; 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; 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; 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.

[0022] Furthermore, the specific control process of the dynamic adjustment control module is as follows:

[0023] (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;

[0024] (2) Determine the type of L-type impedance matching network based on the initial impedance value and the externally provided target impedance value and high and low pass requirements, and then control the switches in the inductor array and capacitor array to form the corresponding type of topology of the L-type impedance matching network;

[0025] (3) Based on 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;

[0026] (4) Control the 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;

[0027] (5) Reusing the real-time impedance measurement module to calculate the equivalent load impedance value Z of the ultrasonic transducer as the actual impedance value;

[0028] (6) Based on 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 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;

[0029] (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 adjustment optimization;

[0030] (8) Determine whether there is a real-time matching requirement: if so, execute step (5); if not, execute step (9);

[0031] (9) The matching is completed, and the current structure of the L-type impedance matching network is maintained.

[0032] Furthermore, the criteria for determining the type of the L-type impedance matching network in step (2) are as follows:

[0033] When R≤Z r And when high-pass is required externally, the L-type impedance matching network is a high-pass impedance reduction type;

[0034] When R≤Z r And when low-pass is required externally, the L-type impedance matching network is a low-pass impedance reduction type;

[0035] when , Z i ≥0 and when high-pass is required externally, the L-type impedance matching network is a high-pass impedance-enhancing type;

[0036] when , Z i ≥0 and when low-pass is required externally, the L-type impedance matching network is a low-pass impedance reduction type;

[0037] when , Z i When <0 and high-pass is required externally, the L-type impedance matching network is a high-pass impedance reduction type;

[0038] when , Z i When <0 and low-pass is required externally, the L-type impedance matching network is a low-pass impedance-enhancing type;

[0039] when And when high-pass is required externally, the L-type impedance matching network is a high-pass impedance-enhancing type;

[0040] when And when low-pass is required externally, the L-type impedance matching network is a low-pass impedance-raising type;

[0041] 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.

[0042] Furthermore, in step (3) and step (6), the inductance value of the inductor array and the capacitance value of the capacitor array are calculated by the following formulas;

[0043] If the L-type impedance matching network is a low-pass impedance reduction type, then:

[0044] ;

[0045] If the L-type impedance matching network is a high-pass impedance reduction type, then:

[0046] ;

[0047] If the L-type impedance matching network is a low-pass impedance-raising type, then:

[0048] ;

[0049] If the L-type impedance matching network is a high-pass impedance-raising type, then:

[0050] ;

[0051] Where: L and C are the inductance of the inductor array and the capacitance 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 and imaginary parts of the equivalent load impedance Z, Y r and Y i are the real and imaginary parts of the admittance value corresponding to the equivalent load impedance value Z respectively.

[0052] Based on the above technical solution, the present invention has the following beneficial technical effects:

[0053] 1. Simplify circuit structure and reduce component count. This invention uses an inductor array and a capacitor array, cleverly combined to implement four different L-shaped impedance matching networks without the need for multiple independent matching components. This approach greatly simplifies circuit design, reduces the number of components required in the system, and lowers cost and complexity.

[0054] 2. Improved matching flexibility. Different ultrasonic transducers, operating frequencies, and load conditions may require different optimal impedance matching network types. By providing four switchable L-type matching networks, this invention can flexibly adapt to different impedance characteristics, ensuring that the appropriate matching solution can be found in various operating environments and optimizing power transmission.

[0055] 3. Reduce power reflection and reactive power consumption. By matching the load equivalent impedance to a purely resistive impedance, this invention reduces power reflection and reactive power consumption caused by impedance mismatch. This reduces reflected power and heat generation between the transducer and driver, thus preventing system performance degradation.

[0056] 4. Adaptability to complex operating conditions. This invention enables real-time dynamic adjustment to adapt to changes in the ultrasonic transducer's impedance under varying loads and operating environments. Compared to traditional static matching methods, this invention's dynamic adjustment capability can cope with diverse operating conditions, ensuring excellent matching performance even in complex and dynamic operating conditions.

[0057] 5. Improve driver efficiency and system stability. The present invention's dynamic matching network adjustment method can effectively adjust the equivalent impedance of the ultrasonic transducer, ensuring optimal matching between the driver and the load. When the ultrasonic transducer impedance is too low, the present invention reduces the driver's current load by increasing the impedance of the matching network, avoiding driver damage or instability caused by overload. When the transducer impedance is too high, the present invention ensures that the driver can provide sufficient current and power by reducing the impedance of the matching network, avoiding the problem of reduced drive efficiency due to too light a load. This dynamic matching mechanism effectively improves the overall operating efficiency of the driver and the stability of the system, ensuring efficient drive under different load conditions.

[0058] 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 real-time operating conditions to meet a wider range of load change requirements, thereby ensuring that the driver can operate stably and efficiently under various conditions. This innovation effectively compensates for the shortcomings of existing technologies and significantly improves the adaptability and performance of ultrasonic equipment in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Schematic diagram of the circuit structure of the reconfigurable L-shaped dynamic impedance matching network of the ultrasonic transducer of the present invention.

[0060] Figure 2 Schematic diagram of four L-type impedance matching networks and their equivalent structures of the matching network switching module.

[0061] Figure 3 Schematic diagram of the structure of the inductor array.

[0062] Figure 4 Schematic diagram of the capacitor array structure.

[0063] Figure 5 Schematic diagram of the control workflow of the dynamic adjustment control module. DETAILED DESCRIPTION

[0064] In order to describe the present invention more specifically, the technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0065] like Figure 1As shown, this embodiment provides a reconfigurable L-shaped dynamic impedance matching network system for an ultrasonic transducer, which is inserted between a driver and an ultrasonic transducer. By dynamically adjusting the matching network structure, the power transmission efficiency is improved. The circuit system mainly includes a real-time impedance measurement module 1, a matching network switching module 2, and a dynamic adjustment control module 3, wherein:

[0066] The real-time impedance measurement module 1 comprises a voltage measurement module 11, a current measurement module 12, a synchronous analog-to-digital conversion module 13, and an impedance calculation unit 14. It can perform impedance measurements while the driver is continuously outputting power, without interrupting the excitation signal. The voltage measurement circuit 11 monitors the voltage difference between the positive and negative lines at the driver's output in real time. Because the voltage difference between the positive and negative lines is typically large, a resistor divider is used, followed by an op amp buffer. A differential amplifier is then used to adjust the signal to a level suitable for the input range of the synchronous analog-to-digital conversion module 13. The current measurement module 12 uses a current transformer on the negative line, then uses a load resistor to convert the secondary current of the current transformer into a level suitable for the input range of the synchronous analog-to-digital conversion module 13. The current measurement module 12 can also use a low-resistance, high-precision precision resistor in series. The voltage difference across the precision resistor is amplified by a differential amplifier to a level 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 and current signals and feeds them into the impedance calculation unit 14. To ensure accuracy, the sampling frequency must be at least 20 times the ultrasonic operating frequency. The impedance calculation unit 14 uses discrete Fourier transform (DFT) to accurately separate specific frequency components and calculate the amplitude and phase difference of voltage and current at the ultrasonic operating frequency. Based on the collected voltage and current amplitude and phase difference, the equivalent load impedance value of the ultrasonic transducer at the operating frequency is calculated. The formula is: The impedance value Z obtained by real-time measurement can be expressed as the sum of the real part and the imaginary part, that is, Z=Z r +jZ i The corresponding admittance of the impedance can also be expressed as 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 driver operation, and impedance monitoring can be completed without interrupting the drive signal.

[0067] The matching network switching module 2 is composed of a reconfigurable L-shaped impedance matching network, including an inductor array 21, a capacitor array 22, and four single-pole double-throw switches 23, 24, 25, and 26. By switching the switch directions of the four single-pole double-throw switches 23, 24, 25, and 26, four different L-shaped impedance matching networks can be formed, corresponding to low-pass impedance reduction type, low-pass impedance increase type, high-pass impedance reduction type, and high-pass impedance increase type, such as Figure 2As shown. The single-pole double-throw switch 23 is connected to the positive line, the single-pole double-throw switch 24 is connected to the negative line, the single-pole double-throw switch 25 is connected to the positive line, and the single-pole double-throw switch 26 is connected to the positive line, thus forming a low-pass impedance-reducing matching network; the single-pole double-throw switch 23 is connected to the positive line, the single-pole double-throw switch 24 is connected to the positive line, the single-pole double-throw switch 25 is connected to the positive line, and the single-pole double-throw switch 26 is connected to the negative line, thus forming a low-pass impedance-increasing matching network; the single-pole double-throw switch 23 is connected to the negative line, the single-pole double-throw switch 24 is connected to the positive line , the single-pole double-throw switch 25 is connected to the positive line, and the single-pole double-throw switch 26 is connected to the positive line, thus forming a high-pass impedance reduction matching network; the single-pole double-throw switch 23 is connected to the positive line, the single-pole double-throw switch 24 is connected to the positive line, the single-pole double-throw switch 25 is connected to the negative line, and the single-pole double-throw switch 26 is connected to the positive line, thus forming a low-pass impedance increase matching network; the four single-pole double-throw switches 23, 24, 25, and 26 are composed of relay devices, and the negative line of the driver is short-circuited with the negative line of the ultrasonic transducer.

[0068] The inductor array consists of N exponentially stepped inductors L1~L N Each inductor is connected in parallel with a single-pole single-throw switch (corresponding to S L1 ~S LN ) is used to control whether the inductor is connected to the series array, such as Figure 3 When the SPST switch is open, the inductor is normally connected to the series array; when the SPST 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, so a total of 2 N Different combinations. In order to ensure the performance of the matching network, the inductor adopts a magnetically shielded high-frequency power inductor; in actual applications, the inductance value cannot be any required value. Commercial magnetically shielded high-frequency power inductors generally adopt the E series standard value, so it is necessary to adopt an inductor with a close to exponential step. In this embodiment, 11 magnetically shielded high-frequency power inductors are used, and the inductance values ​​are 0.047uH, 0.1uH, 0.22uH, 0.47uH, 0.82uH, 1.5uH, 3.3uH, 6.8uH, 10uH, 22uH, and 47uH respectively. The inductor array formed can be composed of 2048 different inductance combinations from 0 to 92.257uH, and the single-pole single-throw switch is implemented by a relay.

[0069] The capacitor array consists of N exponentially stepped capacitors C1~C N Each capacitor is connected in series with a single-pole single-throw switch (corresponding to S C1 ~S CN ) is used to control whether the capacitor is connected to the parallel array, such as Figure 4When the SPST switch is closed, the capacitor is normally connected to the parallel array; when the SPST 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 values ​​of the capacitors connected to the parallel array, so a total of 2 N Different combinations. In order to ensure the performance of the matching network, the capacitors use ceramic capacitors with good frequency characteristics; in actual applications, the capacitance value cannot be any desired value. Commercial ceramic capacitors generally use E series standard values, so it is necessary to use capacitors close to exponential steps. In this embodiment, 11 ceramic capacitors are used, with capacitance values ​​of 0.047nF, 0.1nF, 0.22nF, 0.47nF, 0.82nF, 1.5nF, 3.3nF, 6.8nF, 10nF, 22nF, and 47nF, respectively. The capacitor array formed can be composed of 2048 different capacitance combinations from 0 to 92.257nF, and the single-pole single-throw switch is implemented using a relay.

[0070] In practical applications, the impedance is generally matched to a purely resistive impedance. Let this impedance point be R, let the ultrasonic operating angular frequency be ω, and the ultrasonic transducer impedance Z=Z r +jZ i , the corresponding admittance Y=Y r +jY i .

[0071] For a low-pass impedance-reducing matching network, the required parallel capacitance is , the required series inductance value When Z i ≤0, the target R can be any value less than or equal to Z r The value of Z i > 0, the target R can be any value less than or equal to The value of .

[0072] For high-pass impedance-reducing matching networks, the required parallel inductance is , the capacitance value required in series When Z i ≥0, the target R can be any value less than or equal to Z r The value of Z i <0, the target R can be any value less than or equal to The value of .

[0073] For the low-pass impedance-raising matching network, the required series inductor value is L= , the required parallel capacitance value When Z i ≥0, the target R can be any value greater than or equal to The value of Z i<0, the target R can be any value greater than or equal to Z r The value of .

[0074] For high-pass impedance matching networks, the required series capacitance value , the required parallel inductance value L= When Z i ≤0, the target R can be any value greater than or equal to The value of Z i > 0, the target R can be any value greater than or equal to Z r The value of .

[0075] Therefore, when choosing the matching network type, you can refer to Table 1:

[0076] Table 1

[0077]

[0078] 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. The on and off state combinations of all single-pole single-throw switches of the inductor array and the capacitor array are listed, and the theoretical inductance value and theoretical capacitance value corresponding to each on and off state are calculated and listed in a table, and arranged in order of value; because in practice, inductors and capacitors are not ideal components, there are various non-ideal characteristics, which makes the inductance value and capacitance value displayed during operation deviate from the marked theoretical value. Therefore, in the real-time matching process, it is necessary to gradually adjust the inductor array and the capacitor array to approach the target value. The specific steps are as follows: Figure 5 As shown:

[0079] S301: Before impedance matching, the load impedance must be measured. Switches 23 and 25 are connected to the positive terminals, the inductor array value is set to 0, and switches 24 and 26 are connected to the negative terminals. This establishes a direct connection from the driver to the ultrasonic transducer. After the driver is activated and energized, the real-time impedance measurement module 1 is used to measure and calculate the ultrasonic transducer impedance and corresponding admittance.

[0080] S302: Based on the target impedance value R and the initial impedance value imaginary part Z i According to the requirements of high-pass and low-pass, the corresponding matching network type is selected according to the above table, and the switching directions of the single-pole double-throw switches 23, 24, 25, and 26 are controlled to form the matching network switching module 2 into the corresponding impedance matching network type.

[0081] S303: Calculate theoretical capacitance values ​​and theoretical inductance values ​​required for the capacitor array and the inductor array in the matching network switching module 2 according to a formula based on the target impedance value, the initial impedance value, and the matching network type.

[0082] S304: According to the theoretical capacitance value and the theoretical capacitance value, the capacitor array and the inductor array are switched to a combination closest to the theoretical value.

[0083] S305: Re-measure and calculate the equivalent load impedance value and the corresponding admittance value of the current ultrasonic transducer using the real-time impedance measurement module 1.

[0084] S306: The current equivalent load impedance value and the corresponding admittance value of the ultrasonic transducer are compared with the initial ultrasonic transducer impedance value and the corresponding admittance value, and the effective capacitance value of the current capacitor array and the effective inductance value of the current inductor array are calculated based on the currently used impedance matching network configuration. The capacitance value to be adjusted is the difference between the effective capacitance value of the current capacitor 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 inductor array and the required theoretical inductance value calculated in S303.

[0085] S307: Determine whether the capacitance and inductance values ​​currently required to be adjusted are less than the minimum step value: If so, it is currently impossible to continue adjusting and optimizing the matching network switching module 2, and proceed to step S308; otherwise, proceed to step S304 and continue adjusting and optimizing.

[0086] S308: If there is a real-time matching requirement, return to step S305 and continue to monitor the load impedance value to see whether it is necessary to adjust and optimize the matching network switching module 2; if there is no real-time matching requirement, proceed to step S309.

[0087] S309: Matching is completed, and the current impedance matching network shape is maintained.

[0088] In summary, the core technical points and innovations of the present invention are mainly reflected in the following points:

[0089] 1. Reconfigurable L-shaped impedance matching network structure. This invention utilizes inductor and capacitor arrays and four single-pole, double-throw switches to dynamically reconfigure four types of L-shaped matching networks to accommodate different impedance matching requirements. The appropriate impedance matching network type can be selected based on the target impedance, ultrasonic transducer impedance, and high-pass and low-pass requirements.

[0090] 2. Step-by-step dynamic adjustment mechanism of inductor / capacitor array. In the system of the present invention, the inductor and capacitor array adopts exponential step adjustment mode, using N exponential step devices to achieve a maximum of 2 N The level of matching accuracy greatly improves the dynamic range, flexibility and accuracy of impedance matching.

[0091] 3. Impedance-matching inductance and capacitance theoretical value calculation method. This invention provides a precise calculation method for inductance and capacitance based on the load impedance characteristics and target impedance of an ultrasonic transducer. Based on the transducer's operating frequency, actual load impedance, target impedance, and impedance matching network type, this method uses a complex impedance matching formula, considers both the imaginary and real parts of the impedance, separates and accurately calculates the inductance and capacitance component values, and calculates the theoretical values ​​of the optimal matching inductance and capacitance.

[0092] 4. Real-time Impedance Measurement Module Design. This invention achieves high-precision, real-time impedance measurement at the ultrasonic transducer's operating frequency through synchronous voltage and current sampling and discrete Fourier transform calculation, avoiding interference from multi-frequency signals. Furthermore, voltage and current sampling does not interfere with the driver output and can be performed synchronously and in real time.

[0093] 5. Fully closed-loop dynamic adjustment and control system. This invention dynamically adjusts the matching network based on real-time impedance measurement and the calculated effective values ​​of the inductor and capacitor arrays, achieving high-speed closed-loop control and ensuring optimal matching between the load impedance and the target impedance.

[0094] 6. Dynamically adjust matching accuracy and tolerance control. When the matching error exceeds a set threshold, the system automatically fine-tunes the inductance / capacitance matrix to achieve high-precision matching and ensure optimal ultrasonic energy transmission efficiency.

[0095] 7. Miniaturized, high-Q, and low-component matching network design. This invention utilizes low-loss, miniaturized, high-Q commercial inductors and capacitors to reduce signal attenuation in the matching network and ensure efficient ultrasonic power transmission. Furthermore, the invention utilizes exponentially stepped permutations and combinations, allowing a small number of components to form an exponential number of combinations. This allows for a miniaturized overall circuit design, making it suitable for portable or embedded ultrasound applications.

[0096] The above description of the embodiments is intended to facilitate understanding and application of the present invention by those skilled in the art. It is apparent that those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without requiring creative effort. Therefore, the present invention is not limited to the above embodiments. Any improvements or modifications made by those skilled in the art based on the disclosure of the present invention should fall within the scope of protection of the present invention.

Claims

1. A reconfigurable L-shaped dynamic impedance matching network system for an ultrasonic transducer, characterized by: 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, thereby calculating 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 thereby changes the topology of the impedance matching network to achieve impedance matching; The real-time impedance measurement module includes: The voltage measurement module is used to measure and acquire the voltage signal at the output end of the driver; The 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 to digital quantities; The impedance calculation unit uses the digitized voltage signal and current signal to extract the frequency components of the voltage signal and 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 through the following formula; Where: |U(ω)| and are the amplitude and phase of U, |I(ω)| and are the amplitude and phase of I, j is the imaginary unit, e is the natural constant, and ω is the operating frequency of the ultrasonic transducer; The matching network switching module adopts a reconfigurable L-shaped impedance matching network, which includes an inductor array, a capacitor array and four single-pole double-throw switches S1 to 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; 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 sequentially 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 sequentially stepped exponentially; 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; 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, the target impedance value provided externally, and the high and low pass requirements, and then control the switches in the inductor array and the capacitor array to form a corresponding type of topology of the L-type impedance matching network; 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 is a high-pass impedance-enhancing type; when And when low-pass is required externally, the L-type impedance matching network is a low-pass impedance-raising 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; (3) Calculating the inductance of the inductor array and the capacitance of the capacitor array based on the initial impedance value, the target impedance value, and the type of the L-type impedance matching network, and using them 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) Reusing the real-time impedance measurement module to calculate the equivalent load impedance value Z of the ultrasonic transducer as the actual impedance value; (6) Calculate the inductance value of the inductor array and the capacitance value of the capacitor array according to the actual impedance value, the target impedance value, and the type of the L-type impedance matching network, and use them as effective values; and use 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 adjustment optimization; (8) Determine whether there is a real-time matching requirement: if so, execute step (5); if not, execute step (9); (9) Matching is completed, and the current structure of the L-type impedance matching network is maintained; 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 respectively, Y r and Y i are the real and imaginary parts of the admittance value corresponding to the equivalent load impedance value Z respectively.

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