Constant-power multi-dimensional fuzzy control ultrasonic transmitting system
The ultrasonic transmitting system, which utilizes multidimensional fuzzy PID control and constant power regulation, solves the problems of low energy conversion efficiency and unstable output of transducers in HIFU systems, achieving efficient and stable power output and a longer equipment lifespan.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-14
- Publication Date
- 2026-04-10
AI Technical Summary
In existing HIFU systems, traditional piezoelectric transducers have low electroacoustic conversion efficiency, resulting in high energy loss, which affects the accuracy of focal temperature control and the clarity of ablation boundaries. Furthermore, the transducer's performance degrades over long-term operation, making it difficult to accurately control the output energy deviation.
An ultrasonic transmitting system employing constant power multidimensional fuzzy control includes a voltage and current sampling module, a high-frequency control signal generation module, an adjustable inverter power supply with a center tap, an MCU main control module, and a human-machine interaction module. Through multidimensional fuzzy PID control and constant power control, it achieves precise tracking of the resonant frequency point and precise regulation of the actual output power.
It improves the energy conversion efficiency of the transducer, extends the life of the ultrasonic transducer, ensures the stability and accuracy of the output power, avoids energy deviation, and achieves faster response speed and no overshoot.
Smart Images
Figure CN121819201A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ultrasonic transmission technology, specifically a constant power multidimensional fuzzy control ultrasonic transmission system. Background Technology
[0002] Ultrasonic transducers play a crucial role in high-intensity focused ultrasound (HIFU) therapy systems, providing core power output. HIFU technology precisely focuses ultrasound waves onto target tissues within the body, utilizing thermal, cavitation, and mechanical effects to achieve in-situ ablation of diseased tissues. During this process, the transducer needs to efficiently convert electrical energy into acoustic energy and generate sufficient acoustic power density at the focal point. The main challenge currently facing HIFU systems is the limited electroacoustic conversion efficiency of traditional piezoelectric transducers, resulting in a significant amount of input electrical energy being converted into heat rather than effective therapeutic acoustic energy. This energy loss not only increases the system's cooling burden but also affects the precise control of the focal temperature and the clarity of the ablation boundary. Furthermore… The performance degradation of transducers under prolonged high-power operation can also affect the working effect. Therefore, improving the energy conversion efficiency of HIFU transducers, enhancing their thermal management performance, and optimizing their acoustic field characteristics have become key technical paths to improve the safety, effectiveness, and controllability of HIFU. However, during long-term use, the actual output energy of the transducer may not be deviated to a certain extent due to the offset of the transducer's resonant point or the aging of circuit circuit components. Existing technologies only track the efficiency of the transducer output through the feedback voltage and current phase difference, and have not effectively controlled the actual output power, making it impossible to more accurately control the output acoustic power. Summary of the Invention
[0003] The purpose of this invention is to provide a constant power multidimensional fuzzy control ultrasonic transmitting system to solve the problems raised in the prior art.
[0004] To achieve the above objectives, the present invention provides the following technical solution: a constant power multidimensional fuzzy control ultrasonic transmitting system, the system comprising a voltage and current sampling module, a high-frequency control signal generation module, an adjustable inverter power supply with a center tap, an MCU main control module, and a human-machine interaction module; The voltage and current sampling module is used to output the sampled raw signal, scale the acquired raw signal, and collect the time difference between the power-on time of the voltage and current. The high-frequency control signal generation module is used to modulate the frequency of the output high-frequency signal and adjust the dead zone of the high-frequency signal. The inverter power module is used to convert the DC power of the equipment into a high-frequency AC signal and output the high-frequency AC signal to the transducer. The MCU main control module is used to receive the output voltage, current and phase difference of the transducer, and to use multi-dimensional fuzzy PID control to track the resonant frequency point to obtain the phase difference. It also uses constant power control to regulate the actual output power, and then controls the entire system through the feedback of the input phase difference and the current power setting and the actual power. The human-computer interaction module consists of a touch display screen, which is used to forward the set parameters to each module through the MCU main control module, thereby realizing the human-computer interaction function.
[0005] Furthermore, the voltage and current sampling module includes a current transformer, a planar transformer, a voltage divider resistor, an RF detector, and a voltage comparator; the current transformer and the planar transformer serve as isolated sampling devices for outputting the sampled raw signal; the voltage divider resistor is used to scale the raw signal to the ADC acquisition range of the MCU; the RF detector is used to process the high-frequency scaled signal into a root mean square voltage signal; and the voltage comparator is used to acquire and process the time difference between the power-on time of the voltage and current.
[0006] Furthermore, the MCU main control module includes a multi-dimensional fuzzy PID control unit and a constant power control unit. The multi-dimensional fuzzy PID control unit is used to track the resonant frequency point and estimate the phase difference when the system is not at the optimal resonant point. The constant power control unit is used to regulate the actual output power when the transducer efficiency reaches its maximum, ensuring that the energy output power meets the human-machine interaction settings through power regulation. When the system is not at the optimal resonant point, the phase difference needs to be estimated by the time difference between the zero-crossing points of voltage sampling and current sampling. When the phase difference is close to 0 or the absolute value is at a certain minimum value, it can be determined that the current transducer efficiency has reached its maximum. While ensuring this maximum efficiency, it is necessary to ensure that the energy output power meets the human-machine interaction settings. The inverter power supply module is controlled by the DAC signal of the main control chip to convert the DC power of the device into a high-frequency AC signal and output the high-frequency AC signal to the transducer, which then outputs controllable ultrasonic power. The inverter power supply module adopts an adjustable inverter power supply with a center tap. The inverter power supply with a center tap is based on a transformer with a center tap. It achieves DC-AC conversion by alternately driving two switches. The output adjustability is achieved by adjusting parameters such as the DC bus, PWM duty cycle or modulation depth, transformer turns ratio, and secondary voltage regulation.
[0007] Furthermore, the multi-dimensional fuzzy PID control unit includes multi-dimensional fuzzy logic and a PID controller. The multi-dimensional fuzzy logic is used to tune the Kp and Ki parameters of the PID controller. The PID controller is an output-limited integral anti-saturation PID controller, which also uses an inverse reduction integral method for integral anti-saturation. For example, when the integral error exceeds 100, only the error opposite to the current integral is accumulated to avoid unexpected accumulation of the integral. At the same time, the frequency setpoint is a combination of the current frequency value and the phase difference. When the phase difference always exists, the frequency setpoint will always run in the direction of the phase difference. Of course, a minimum allowable phase difference will be set at this time. When the phase difference stabilizes around this minimum value, the controller will not actually play a role, avoiding chattering problems similar to sliding mode that are prone to occur when chasing the frequency near the limit value. Moreover, the output value of the PID controller is limited by physical characteristics. When the output value exceeds the allowable range, the output value is limited to the boundary of the allowable range. The output value of the classic PID controller under discrete control is calculated according to the following formula: ; Where Kp, Ki, and Kd are all debugging parameters of the PID controller; e(k) represents the error between the frequency setpoint and the actual value at time k; represents the error between the setpoint and the actual value of the previous cycle; j represents the moment when integration begins; it generally varies from 0 to k, where k is the maximum threshold for cumulative integration, and in this invention, it is set to 20. Specifically, when the integral part of the PID controller is running, only the error within 20 cycles is used for integration; u(k) represents the output value of the entire PID controller; the physical meaning of the output value is the setpoint output under the current frequency tracking strategy; compared with the traditional PID control method, the multi-dimensional fuzzy PID control method, with a relatively complete knowledge base, can achieve a faster response to step changes and does not have the defect of overshoot.
[0008] Furthermore, common fuzzy logic refers to converting the error value and differential error value of a precise physical quantity into membership degrees on a fuzzy set, and then finding the most representative fuzzy control output quantity from this region through defuzzification; the multi-dimensional fuzzy logic, following the fuzzy logic approach, fuzzifies the input values of the fuzzy logic according to the set voltage, set frequency, and differential value of the set frequency; the fuzzification process involves fuzzifying the bus voltage set value, frequency set value, and frequency differential value inputs, and then obtaining the fuzzy control output quantity through defuzzification; Since the inverter circuit used in this invention is relatively stable, the bus voltage setting will not be too frequent. The introduction of a slight component of the voltage setting value will not have too much impact on the current frequency tracking control. Therefore, it will not be used as the basis for fuzzification for the time being. On the contrary, the bus voltage setting value, frequency setting value, and frequency slight component setting value play a more important role in the subsequent parameter tuning of the PID controller. Therefore, the parameters of the output frequency PID control of the above three variables are calibrated accordingly. The selected bus voltage setting value, frequency setting value, and frequency slight component setting value are scanned respectively. The total output power is sampled under each physical quantity. The fuzzification logic is tuned according to the influence characteristics of the three physical quantities on the power output value. The tuning of various rules in the knowledge base of fuzzy control is based on the known characteristics of the transducer. The variation of Kp and Ki is tuned according to the changes in power under the influence of different physical quantities. When the power is at a peak at a certain frequency, it is easier to achieve stable frequency tracking when Kp is tuned to a lower value. When the power is at a trough, it is easier to achieve rapid frequency tracking when Kp is tuned to a higher value. When the power is steep in a certain bandwidth, it is easier to cause oscillation when Ki is tuned to a higher value. If the power change is gradual, the value of parameter Ki is reduced, which can be reduced to a value close to 0, because when the power change is gradual, it is necessary to minimize the impact of integral saturation.
[0009] Furthermore, the frequency fuzzy domain is tuned using the Kp curve calibrated by the transducer, with the tuning method involving approximating the positions of each peak point. However, because the frequency emitted by the waveform generator is relatively stable, the fuzzy domain of the frequency error can be tuned into four domains through historical data analysis. These domains are adjusted using oscillation levels. Based on the impact of frequency error changes on the system, the tuning rules can be derived: if the frequency error is larger, the Kp parameter needs to be larger to follow the frequency change more quickly, and the output domain corresponding to the current input will be tuned in an incremental manner. Similarly, if the voltage is higher, the output domain of Kp should be reduced accordingly. When the frequency error value is large, at frequency peaks, Kp will be appropriately adjusted upwards while ensuring system stability, achieving a balance between stability and speed, and leveraging the advantages of fuzzy control and PID control.
[0010] Furthermore, the constant power control unit achieves power control through feedback of the corresponding current. During power control, the output level is first set via the human-machine interface. After setting the output level, the host computer sends the power parameters corresponding to the set level, and then sends the pulse width setting corresponding to the power parameters. After the pulse width setting is completed, a slow-up and slow-down dead-zone strategy is implemented. The pulse width increases linearly according to the power level value, with one pulse width value corresponding to one level. The slow-up and slow-down dead-zone strategy analyzes whether the level changes and then gradually changes the dead-zone time according to the power slow-up and slow-down principle. The slow-up and slow-down dead-zone process includes the following steps: S1. Determine whether the power setting value is different from the actual setting value; if the power setting value is different from the actual setting value, proceed to step S2; if the power setting value is the same as the actual setting value, proceed to step S3. S2. Analyze whether the power setting value is higher than the actual setting value; if the power setting value is higher than the actual setting value, increase the duty cycle; if the power setting value is lower than the actual setting value, decrease the duty cycle. S3. Complete the PWM signal update.
[0011] Furthermore, after each power output cycle, the effective power output of the current transducer is calculated based on the sampled values of voltage and current. This effective power is then compared with the set power, and the difference between the effective power and the set power is fine-tuned using a fine-tuning function. The fine-tuning formula is as follows: ; Where is the output voltage fine-tuning amount; x is the current power error value; K is 20% of the current power setting value; when the difference between the set power value and the actual power value exceeds 20% of the set power value, it is determined that the influence of the fine-tuning voltage on the power reaches 20%, and it is determined that increasing the fine-tuning voltage cannot compensate for the power difference in time. In this case, the bus voltage will only be adjusted according to the upper or lower limit that can be adjusted at this time; at this time, 20% of the set power value is calibrated as K. The main purpose of this strategy is to use voltage to compensate for sound power, so that the constant power strategy is more stable. The voltage fine-tuning amount is the upper and lower limits of each bus voltage adjustment, and the power error is the difference between the set value and the actual power feedback value. The influence of bus voltage change on the overall power change is linear. When the power is affected by any external influence, the bus voltage is adjusted by the fine-tuning amount formula to successfully complete the constant power output, thereby compensating the output power to the set value.
[0012] Furthermore, the calculated voltage fine-tuning amount is added to the set voltage value to obtain the actual set voltage value of the circuit; the adjustable voltage value is limited, and the voltage adjustment range is controlled within [-u, u], u=5V, that is, the absolute value range of the adjustable voltage is set to 5V; thus avoiding the voltage being adjusted too high and reaching the system adjustment limit; if the adjustment exceeds the physical characteristics limit of the circuit, the amplitude is limited according to the minimum allowable range of the circuit.
[0013] Compared with the prior art, the beneficial effects of the present invention are: This invention, based on multi-dimensional fuzzy control, achieves constant power output while ensuring frequency tracking, and also extends the lifespan of the ultrasonic transducer to a certain extent. It effectively solves problems such as inaccurate resonant point tracking and power output deviation caused by aging circuit components after prolonged use, ensuring stable output power at the set output power point each time, effectively eliminating the problem of unstable transducer output energy and achieving more precise power output. Compared with traditional PID control methods, the multi-dimensional fuzzy PID control method proposed in this invention, with a more complete knowledge base, can achieve faster step response and avoids overshoot defects. When the frequency error value is large, at frequency peaks, this invention appropriately adjusts the PID control parameters upwards while ensuring system stability, achieving a balance between stability and speed, and leveraging the advantages of both fuzzy and PID control. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the structure of a constant power multidimensional fuzzy control ultrasonic transmitting system according to the present invention; Figure 2 This is a schematic diagram of the multi-dimensional fuzzy control process of a constant power multi-dimensional fuzzy control ultrasonic transmitting system according to the present invention. Figure 3 This is a schematic diagram of the fuzzification process of an ultrasonic transmitting system with constant power multidimensional fuzzy control according to the present invention. Figure 4 This is a PID parameter calibration curve diagram of a constant power multidimensional fuzzy control ultrasonic transmitting system according to the present invention; Figure 5 This is a schematic diagram of the fuzzification rules for a constant power multidimensional fuzzy control ultrasonic transmitting system according to the present invention. Figure 6 This is a schematic diagram of the constant power control process of an ultrasonic transmitting system with constant power multidimensional fuzzy control according to the present invention. Figure 7 This is a schematic diagram of the dead zone gradual rise and fall process of an ultrasonic transmitting system with constant power multidimensional fuzzy control according to the present invention. Figure 8 This is a schematic diagram of voltage adjustment for a constant power multidimensional fuzzy control ultrasonic transmitting system according to the present invention. Detailed Implementation
[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0016] Example: Figures 1-8 As shown, the present invention provides a technical solution: a constant power multidimensional fuzzy control ultrasonic transmitting system, such as... Figure 1 As shown, the system includes a voltage and current sampling module, a high-frequency control signal generation module, an adjustable inverter power supply with a center tap, an MCU main control module, and a human-machine interaction module. The voltage and current sampling module is used to output the sampled raw signal, scale the acquired raw signal, and collect the time difference between the power-on time of the voltage and current. The high-frequency control signal generation module is used to frequency modulate the output high-frequency signal and adjust the dead zone of the high-frequency signal. The inverter power supply module is used to convert the DC power supply of the equipment into a high-frequency AC signal and output the high-frequency AC signal to the transducer; The MCU main control module is used to receive the output voltage, current and phase difference of the transducer, and to use multi-dimensional fuzzy PID control to track the resonant frequency point to obtain the phase difference. It also uses constant power control to regulate the actual output power, and then controls the entire system through the feedback of the input phase difference and the current power setting and the actual power. The human-computer interaction module consists of a touch display screen, which is used to forward the set parameters to each module through the MCU main control module to realize the human-computer interaction function.
[0017] The voltage and current sampling module includes a current transformer, a planar transformer, a voltage divider resistor, an RF detector, and a voltage comparator. The current transformer and the planar transformer serve as isolated sampling devices for outputting the original sampled signal. The voltage divider resistor is used to scale the original signal to the ADC acquisition range of the MCU. The RF detector is used to process the high-frequency scaled signal into a root mean square voltage signal. The voltage comparator is used to acquire and process the time difference between the power-on time of the voltage and current.
[0018] The MCU main control module includes a multi-dimensional fuzzy PID control unit and a constant power control unit. The multi-dimensional fuzzy PID control unit is used to track the resonant frequency point and estimate the phase difference when the system is not at the optimal resonant point. The constant power control unit is used to regulate the actual output power when the transducer efficiency reaches its maximum, and ensure that the energy output power meets the human-machine interaction settings through power regulation. When the system is not at the optimal resonant point, the phase difference needs to be estimated by the time difference between the zero-crossing points of voltage sampling and current sampling. When the phase difference is close to 0 or the absolute value is at a certain minimum value, it can be determined that the current transducer efficiency has reached its maximum. Under the condition of ensuring the maximum efficiency, it is necessary to ensure that the energy output power meets the human-machine interaction settings. The inverter power supply module is controlled by the DAC signal of the main control chip to convert the DC power of the equipment into a high-frequency AC signal, and outputs the high-frequency AC signal to the transducer, which then outputs controllable ultrasonic power.
[0019] like Figure 2 As shown, the multi-dimensional fuzzy PID control unit includes multi-dimensional fuzzy logic and a PID controller. The multi-dimensional fuzzy logic is used to tune the Kp and Ki parameters of the PID controller. The PID controller is an output-limited integral anti-saturation PID controller, and it also uses the inverse reduction integral method for integral anti-saturation. For example, when the integral error exceeds 100, only the error opposite to the current integral is accumulated to avoid unexpected accumulation of the integral. At the same time, the frequency setpoint is a combination of the current frequency value and the phase difference. When the phase difference always exists, the frequency setpoint will always run in the direction of the phase difference. Of course, a minimum allowable phase difference is set. When the phase difference stabilizes around this minimum value, the controller will not actually play a role, avoiding chattering problems similar to sliding mode that are prone to occur when chasing the frequency near the limit value. Furthermore, the output value of the PID controller is limited by physical characteristics. When the output value exceeds the allowable range, the output value is limited to the boundary of the allowable range. The output value of the classic PID controller under discrete control is calculated according to the following formula: ; Where Kp, Ki, and Kd are all debugging parameters of the PID controller; e(k) represents the error between the frequency setpoint and the actual value at time k; represents the error between the setpoint and the actual value of the previous cycle; j represents the moment when integration begins; it generally varies from 0 to k, where k is the maximum threshold for cumulative integration, and in this invention, it is set to 20. Specifically, when the integral part of the PID controller is running, only the error within 20 cycles is used for integration; u(k) represents the output value of the entire PID controller; the physical meaning of the output value is the setpoint of the frequency output under the current frequency tracking strategy.
[0020] Common fuzzy logic involves converting the error values and differential error values of precise physical quantities into membership degrees on a fuzzy set, and then defuzzifying to find the most representative fuzzy control output quantity from that region. Multi-dimensional fuzzy logic, following the fuzzy logic approach, fuzzifies the input values of the fuzzy logic according to the set voltage, set frequency, and the differential value of the set frequency; for example... Figure 3 As shown, the fuzzification process involves fuzzifying the input bus voltage setpoint, frequency setpoint, and frequency differential setpoint, performing fuzzy inference based on the inference knowledge base, and then obtaining the fuzzy control output after defuzzification. Since the inverter circuit used in this invention is relatively stable, the bus voltage setting will not be too frequent. The introduction of a slight component of the voltage setting value will not have too much impact on the current frequency tracking control. Therefore, it will not be used as the basis for fuzzification for the time being. On the contrary, the bus voltage setting value, frequency setting value, and frequency slight component setting value play a more important role in the subsequent parameter tuning of the PID controller. Therefore, the parameters of the output frequency PID control of the above three variables are calibrated accordingly. The selected bus voltage setting value, frequency setting value, and frequency slight component setting value are scanned respectively. The total output power is sampled under each physical quantity. The fuzzification logic is tuned according to the influence characteristics of the three physical quantities on the power output value. Based on the known transducer characteristics, the fuzzy control is tuned using various rules from a knowledge base. The variation patterns of Kp and Ki are determined according to the power variation under the influence of different physical quantities. When the power at a certain frequency is a peak, a lower Kp value makes stable frequency tracking easier; when the power is at a trough, a higher Kp value makes rapid frequency tracking easier. When the power is steep within a certain bandwidth, a higher Ki value is more likely to cause oscillations. If the power change is gradual, the Ki value is reduced, even to a value close to 0, because in cases of gradual power change, it is necessary to minimize the impact of integral saturation. For example, the calibrated curve obtained from the above rules and calibration is as follows: Figure 4 As shown, based on the calibrated curves and control experience, corresponding fuzzification rules for Kp and Ki are formulated. In the selection of the membership function in the Kp rule, a triangular membership function is adopted. The fuzzy universe of the fuzzy variables is represented by fuzzy sets: f = {PEAK1, PEAK2, PEAK3, PEAK4, PEAK5}, E(f) = {LEVEL1, LEVEL2, LEVEL3, LEVEL4}. The formulated fuzzification rules are as follows: Figure 5 As shown.
[0021] The frequency fuzzy domain is tuned using the Kp curve calibrated by the transducer, with the tuning method approximating the positions of each peak point. However, because the frequency emitted by the waveform generator is relatively stable, the fuzzy domain of the frequency error can be tuned into four domains through historical data analysis. These domains are adjusted using oscillation levels. Analysis of the impact of frequency error changes on the system reveals the following tuning rules: a larger frequency error requires a larger Kp parameter to follow frequency changes more quickly, and the output domain corresponding to the current input will be tuned incrementally. Similarly, a higher voltage requires a corresponding decrease in the output domain of Kp. When the frequency error is large, at frequency peaks, Kp will be adjusted upwards appropriately while ensuring system stability, achieving a balance between stability and speed, and leveraging the advantages of fuzzy control and PID control. A constant power control unit achieves power control through feedback of the corresponding current; during power control, such as... Figure 6 As shown, the output level is first set through the human-machine interface. After the output level is set, the host computer sends the power parameter corresponding to the set level, and then sends the pulse width setting corresponding to the power parameter. After the pulse width setting is completed, a dead-time gradual increase and decrease strategy is implemented. The pulse width increases linearly according to the power level value, with one pulse width value corresponding to one level. The dead-time gradual increase and decrease strategy analyzes whether the level changes and then gradually changes the dead time according to the power gradual increase and decrease principle. Figure 7 As shown, the gradual ascent and descent process of the dead zone includes the following steps: S1. Determine whether the power setting value is different from the actual setting value; if the power setting value is different from the actual setting value, proceed to step S2; if the power setting value is the same as the actual setting value, proceed to step S3. S2. Analyze whether the power setting value is higher than the actual setting value; if the power setting value is higher than the actual setting value, increase the duty cycle; if the power setting value is lower than the actual setting value, decrease the duty cycle. S3. Complete the PWM signal update.
[0022] Each time the power output completes one cycle, the effective power output of the transducer is calculated based on the sampled voltage and current values. The effective power is then compared with the set power, and the difference between the effective power and the set power is fine-tuned using a fine-tuning function. The fine-tuning formula is as follows: ; in, denoted as _x_, where _x is the current power error value; and _K_ is 20% of the current power setting value. When the difference between the set power value and the actual power value exceeds 20% of the set power value, it is determined that the influence of the fine-tuning voltage on the power reaches 20%. Therefore, it is determined that increasing the fine-tuning voltage cannot compensate for the power difference in time, and the bus voltage will only be adjusted according to the upper or lower limit that can be adjusted at this time. At this time, 20% of the set power value is calibrated as _K_. The main purpose of this strategy is to use voltage to compensate for acoustic power, making the constant power strategy more stable. like Figure 8 As shown, the voltage fine-tuning amount is the upper and lower limits of each bus voltage adjustment, and the power error is the difference between the set value and the actual power feedback value. The influence of bus voltage change on the overall power change is linear. When the power is affected by any external influence, the bus voltage is adjusted by the fine-tuning amount formula to successfully complete the constant power output, thereby compensating the output power to the set value.
[0023] The calculated voltage adjustment amount is added to the set voltage value to obtain the actual set voltage value of the circuit; the adjustable voltage value is limited to control the voltage adjustment range within [-u, u], u=5V; thus avoiding the voltage adjustment being too high and reaching the system adjustment limit; if the adjustment exceeds the physical characteristics limit of the circuit, the amplitude is limited according to the minimum allowable range of the circuit.
[0024] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A constant-power multidimensional fuzzy control ultrasonic transmitting system, characterized in that: The system includes a voltage and current sampling module, a high-frequency control signal generation module, an inverter power supply module, an MCU main control module, and a human-machine interaction module; The voltage and current sampling module is used to output the sampled raw signal, scale the acquired raw signal, and collect the time difference between the power-on time of the voltage and current. The high-frequency control signal generation module is used to modulate the frequency of the output high-frequency signal and adjust the dead zone of the high-frequency signal. The inverter power module is used to convert the DC power of the equipment into a high-frequency AC signal and output the high-frequency AC signal to the transducer. The MCU main control module is used to receive the output voltage, current and phase difference of the transducer, and to use multi-dimensional fuzzy PID control to track the resonant frequency point to obtain the phase difference. It also uses constant power control to regulate the actual output power, and then controls the entire system through the feedback of the input phase difference and the current power setting and the actual power. The human-computer interaction module consists of a touch display screen and is used to forward the set parameters to each module through the MCU main control module.
2. The constant power multidimensional fuzzy control ultrasonic transmitting system according to claim 1, characterized in that: The voltage and current sampling module includes a current transformer, a planar transformer, a voltage divider resistor, an RF detector, and a voltage comparator. The current transformer and the planar transformer serve as isolated sampling devices for outputting the sampled raw signal. The voltage divider resistor is used to scale the raw signal to the ADC acquisition range of the MCU. The RF detector is used to process the high-frequency scaled signal into a root mean square voltage signal. The voltage comparator is used to acquire and process the time difference between the voltage and current power-on times. The inverter power module is controlled by the DAC signal of the main control chip to convert the DC power of the device into a high-frequency AC signal and output the high-frequency AC signal to the transducer, thereby outputting controllable ultrasonic power.
3. The constant power multidimensional fuzzy control ultrasonic transmitting system according to claim 1, characterized in that: The MCU main control module includes a multi-dimensional fuzzy PID control unit and a constant power control unit. The multi-dimensional fuzzy PID control unit is used to track the resonant frequency point and estimate the phase difference when the system is not at the optimal resonant point. The constant power control unit is used to regulate the actual output power when the transducer efficiency reaches its maximum, and ensure that the power output meets the set value of the human-machine interaction through power regulation.
4. The constant power multidimensional fuzzy control ultrasonic transmitting system according to claim 3, characterized in that: The multi-dimensional fuzzy PID control unit includes multi-dimensional fuzzy logic and a PID controller. The multi-dimensional fuzzy logic is used to tune the Kp and Ki parameters of the PID controller. The PID controller is an output-limited integral anti-saturation PID controller, which also employs an inverse integral reduction method for integral anti-saturation. Furthermore, the output value of the PID controller is limited by physical characteristics; when the output value exceeds the allowable range, it is limited to the boundary of the allowable range. The output value of the classic PID controller under discrete control is calculated according to the following formula: ； Where Kp, Ki, and Kd are all debugging parameters of the PID controller; e(k) represents the error between the frequency setpoint and the actual value at time k; represents the error between the setpoint and the actual value of the frequency in the previous cycle; j represents the moment when integration begins; u(k) represents the output value of the entire PID controller.
5. The constant power multidimensional fuzzy control ultrasonic transmitting system according to claim 4, characterized in that: The multi-dimensional fuzzy logic fuzzifies the input values of the fuzzy logic according to the fuzzy logic idea, based on the set voltage, set frequency, and set frequency derivative value. The fuzzification process involves fuzzifying the set voltage, set frequency, and set frequency derivative value inputs, and then obtaining the fuzzy control output value after defuzzification. The selected bus voltage setting, frequency setting, and frequency differential setting are scanned respectively. The total output power is sampled for each physical quantity. Based on the influence characteristics of the three physical quantities on the power output value, the fuzzy logic is tuned. The tuning rules for Kp and Ki are determined based on the changes in power under the influence of different physical quantities. The obtained tuning rules are as follows: at a certain frequency, if the power reaches its peak value, the parameter Kp is reduced; if the power reaches its minimum value, the parameter Kp is increased; at a certain bandwidth, if the power changes steeply, the parameter Ki is increased; if the power changes gradually, the parameter Ki is reduced.
6. The constant power multidimensional fuzzy control ultrasonic transmitting system according to claim 5, characterized in that: The frequency fuzzy domain is tuned by the Kp curve calibrated by the transducer. The tuning method is to approximately select the position of each peak point for tuning. The fuzzy domain of the frequency error can be tuned into four domains through historical data analysis. The corresponding domains are adjusted by the oscillation level. The tuning rules are obtained by analyzing the impact of the frequency error on the system.
7. The constant power multidimensional fuzzy control ultrasonic transmitting system according to claim 3, characterized in that: The constant power control unit achieves power control through feedback of the corresponding current. During power control, the output level is first set via the human-machine interface. After setting the output level, the host computer sends the power parameter corresponding to the set level, and then sends the pulse width setting corresponding to the power parameter. After the pulse width setting is completed, a slow-increase and slow-decrease dead-zone strategy is implemented. The pulse width increases linearly according to the power level value, with one pulse width value corresponding to one level. The slow-increase and slow-decrease dead-zone strategy analyzes whether the level changes and then gradually changes the dead-zone time according to the power slow-increase and slow-decrease principle. The slow-increase and slow-decrease dead-zone process includes the following steps: S1. Determine whether the power setting value is different from the actual setting value; if the power setting value is different from the actual setting value, proceed to step S2; if the power setting value is the same as the actual setting value, proceed to step S3. S2. Analyze whether the power setting value is higher than the actual setting value; if the power setting value is higher than the actual setting value, increase the duty cycle; if the power setting value is lower than the actual setting value, decrease the duty cycle. S3. Complete the PWM signal update.
8. The constant power multidimensional fuzzy control ultrasonic transmitting system according to claim 7, characterized in that: Each time the power output completes one cycle, the effective power output of the transducer is calculated based on the sampled values of voltage and current. This effective power is then compared with the set power, and the difference between the effective power and the set power is fine-tuned using a fine-tuning function. The fine-tuning formula is as follows: ； in, is the output voltage fine-tuning amount; x is the current power error value; K is 20% of the current power setting value; The voltage fine-tuning amount is the upper and lower limits of each bus voltage adjustment, and the power error is the difference between the set value and the actual power feedback value.
9. The constant power multidimensional fuzzy control ultrasonic transmitting system according to claim 8, characterized in that: The calculated voltage adjustment amount is added to the set voltage value to obtain the actual set voltage value of the circuit. The adjustable voltage value is limited, and the voltage adjustment range is controlled within [-u, u]. If the voltage exceeds the physical characteristics of the circuit after adjustment, the voltage is limited according to the minimum allowable range of the circuit.