Electroacoustic emission system and its control method

Abstract

This invention provides an electroacoustic emission system and its control method. The control method includes: presetting a target acoustic signal value p. ref The first error signal p is obtained by subtracting the output acoustic signal of the electroacoustic transducer. ess The first error signal p ess After passing through the first controller, the reference current signal i is obtained. ref Reference current signal i ref Subtract the collected electroacoustic transducer input current signal i e The second error signal i is obtained ess The second error signal i ess After passing through the second controller, the signal wave is output to the PWM modulation module. The output terminal of the PWM modulation module is electrically connected to the control terminal of the single-phase full-bridge inverter switching transistor. The first controller is a PR controller, and the second controller is one of a proportional controller, a PI controller, or a PID controller.

Description

Technical Field

[0001] This invention relates to an electroacoustic emission system and its control method. Background Technology

[0002] In the field of communications, wireless communication in the air primarily relies on radio waves, which travel at the speed of light. However, in underwater communication, current research has found that only sound waves can stably transmit signals, while radio waves and other types experience severe signal attenuation. Electroacoustic transmission systems, acting as signal sources in underwater communication, transmit information to the receiving end and are an indispensable component. In existing electroacoustic transmission systems with electroacoustic transducers, the transducer's drive end is connected to a drive circuit, which includes a single-phase full-bridge inverter, capacitors, and inductors. By controlling the switching transistors of the single-phase full-bridge inverter, the output signal of the drive circuit is adjusted, thereby controlling the electroacoustic transducer. Most existing electroacoustic transducer control structures are open-loop systems, meaning that after manually adjusting the drive circuit and inputting a signal to the transducer, it directly outputs an acoustic signal. This results in difficulty controlling continuous and stable output performance, failing to guarantee the quality of the output acoustic signal, exhibiting extremely poor robustness, and being unable to adapt to complex and changing application environments. To address this, some studies have modeled the transducer, setting reference values ​​based on the established model. By comparing the acquired signal with these reference values, the output signal of the drive circuit is adjusted to control the transducer's output signal. However, the working environment of electroacoustic transducers is complex, and their inherent structure results in nonlinear impedance, making accurate modeling often impossible. This leads to inaccurate reference values ​​determined by the established transducer model, meaning the accuracy of the drive circuit's output signal depends entirely on the accuracy of the transducer model. Consequently, this method typically results in significant errors between the output sound field signal and the target signal, leading to poor control accuracy of the electroacoustic transmission system's transmission power. Summary of the Invention

[0003] The problem this invention aims to solve is that the accuracy of the output signal of an electroacoustic transducer drive circuit depends on the accuracy of the transducer modeling, resulting in poor control accuracy of the transducer output acoustic signal. The invention provides an electroacoustic emission system and its control method.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a control method for an electroacoustic emission system, wherein the electroacoustic emission system includes an electroacoustic transducer and a single-phase full-bridge inverter connected to the drive end of the electroacoustic transducer;

[0005] The control method includes: preset target acoustic signal value p ref The first error signal p is obtained by subtracting the acoustic signal output from the electroacoustic transducer. essThe first error signal p ess After passing through the first controller, the reference current signal i is obtained. ref Reference current signal i ref Subtract the collected electroacoustic transducer input current signal i e The second error signal i is obtained ess The second error signal i ess The signal obtained from the second controller is modulated by PWM to obtain a PWM modulated signal, which is then used to control the switching of the single-phase full-bridge inverter.

[0006] The first controller is a PR controller, and the second controller is one of a proportional controller, a PI controller, or a PID controller.

[0007] In this application, the real-time acoustic signal of the detected electroacoustic transducer is calculated against the target value. The resulting error signal is input to a PR controller (proportional-resonant controller) for processing to obtain an outer loop reference current signal. To improve the system's output performance, a second controller (using one of a proportional controller, proportional-integral controller, or proportional-integral-derivative controller) PI controller is introduced as the inner loop control based on the PR controller. The reference current signal obtained from the outer loop control system is calculated against the electrical input current signal, and the resulting error current signal is input to the second controller in the inner loop. The output of the second controller is output as a signal wave to the PWM modulation module. The output of the PWM modulation module is electrically connected to the control terminal of the single-phase full-bridge inverter's switching transistor. That is, after pulse width modulation, a PWM signal is generated to control the single-phase full-bridge inverter's switching transistor, thereby adjusting the output of the single-phase full-bridge inverter in real time. This application directly compares the target value of the acoustic signal with the acquired acoustic signal and feeds back the difference between the two. That is, the set target value of the acoustic signal will not be affected by the modeling accuracy of the electroacoustic transducer. Therefore, compared with the existing method of setting the target value based on the established electroacoustic transducer model, this application can avoid the influence of the modeling accuracy of the electroacoustic transducer as much as possible and achieve better control accuracy.

[0008] In the above technical solution, the acoustic signal output by the electroacoustic transducer is the average value of the acoustic signals detected at h different detection positions, and the distance between the sound source point (preferably the center of the sound radiation surface) of the electroacoustic transducer and each detection position is equal.

[0009] By setting up the above method, sampling can be performed at multiple locations at the same distance from the acoustic radiation surface of the electroacoustic transducer, and then averaging the results, thereby achieving a noise reduction effect.

[0010] In the above technical solution, the expression of the transfer function of the PR controller in the s-domain is:

[0011]

[0012] Where fa is the frequency of the output voltage signal of the single-phase full-bridge inverter, and k p1,fa k is the proportional coefficient of the PR controller corresponding to the frequency fa. r,fa ω is the resonant coefficient of the PR controller corresponding to the frequency fa. c This is the cutoff angular frequency of the PR controller.

[0013] In the above technical solution, the control method further includes: dividing the operating frequency band of the electroacoustic transducer into K sub-frequency bands with the same frequency band width, where K≥2;

[0014] If fa = f(k), then k p1,fa =k p1,f(k) k r,fa =k r,f(k) ; where k p1,f(k) k r,f(k) These correspond to the preset proportional coefficient and preset resonance coefficient corresponding to the frequency value f(k), respectively, k=0,1,……,K, f(0) and f(K) are the lower limit and upper limit of the working frequency band of the electroacoustic transducer, respectively, and f(1), f(2),……,f(K) are the upper limit values ​​of K sub-frequency bands, respectively;

[0015] Otherwise, if we determine that f(m) < fa < f(m+1), then we can calculate k using the following formula. p1,fa k r,fa :

[0016]

[0017]

[0018] Where △f=[f(K)-f(0)] / K, m is a natural number, 0≤m≤K-1.

[0019] During their research, the applicant discovered that when the electroacoustic transducer operates over a wide frequency range, if the PR controller uses the same proportional gain and resonance coefficient across the entire range, the controller gain significantly decreases at frequencies far from the resonance point. Existing technologies generally employ two methods. One method involves experimentally or through simulation determining the PR controller's proportional gain and resonance coefficient for each operating frequency. When the electroacoustic transducer's operating frequency corresponds to that frequency, the PR controller is assigned the appropriate values. However, determining the proportional gain and resonance coefficient through experimentation or simulation is time-consuming and computationally intensive, especially when the electroacoustic transducer's operating frequency range is large, requiring significant time to obtain preset values ​​and greatly increasing the controller design complexity. Another method involves dividing the controller's operating frequency range into several sub-bands, where the PR controller's proportional gain and resonance coefficient remain constant within each sub-band. This leads to a problem: within each sub-band, the controller gain is high near the resonance frequency, but decreases significantly at frequencies far from the resonance point, affecting the controller's performance.

[0020] In this application, through the above settings, when the operating frequency of the electroacoustic transducer is at the upper or lower limit of the sub-band (i.e., the boundary point of the sub-band), the proportional coefficient and resonance coefficient of the corresponding PR controller are preset values. When the operating frequency of the electroacoustic transducer is at a non-boundary point of the sub-band, the proportional coefficient and resonance coefficient of the PR controller corresponding to the operating frequency are calculated based on the proportional coefficient and resonance coefficient of the upper and lower limits of the sub-band where that frequency is located. That is, the values ​​of the proportional coefficient and resonance coefficient of the PR controller corresponding to the non-boundary point operating frequency depend on its distance from the two endpoint frequencies (the lower and upper limits of the sub-band). If the operating frequency is closer to the lower limit, the proportional coefficient and resonance coefficient are closer to the proportional coefficient and resonance coefficient of the lower limit, and vice versa, so that the values ​​of the proportional coefficient and resonance coefficient of the PR controller change with the operating frequency within the frequency band. The method described in this application avoids the problem of having to conduct experiments to determine the coefficients for each frequency point, which greatly increases the difficulty of controller design. It also avoids the problem of the controller value remaining unchanged in each sub-frequency band, which leads to a significant decrease in the controller gain at the resonant point. As a result, the PR controller is more adaptable to more operating frequency points, and the performance of the PR controller is improved throughout the entire operating frequency band.

[0021] The method described above for determining the PR controller coefficients avoids the need for experiments to determine the coefficients at every frequency point, which greatly increases the design difficulty of the controller. On the other hand, simply dividing the controller coefficients into several segments and keeping the controller value constant in each segment will also lead to a significant decrease in the controller gain at points deviating from the resonant point. This solution effectively addresses this problem.

[0022] In the above technical solution, the transfer function of the PI controller in the s-domain is expressed as follows:

[0023]

[0024] Where, k p2 k is the proportional gain of the PI controller. i The integral coefficient of the PI controller.

[0025] In the above technical solution, the acoustic signal output by the electroacoustic transducer is the result obtained after the acquisition result of the acoustic signal output by the electroacoustic transducer is passed through the first filter.

[0026] In this application, the above settings are used to achieve noise reduction through filtering.

[0027] In the above technical solution, the transfer function of the first filter in the s-domain is expressed as G. LPF (s) is:

[0028]

[0029] Where τ is the time constant, τ=1 / (2×π×f) L ), f L >f max f L f is the cutoff frequency of the first filter. max This is the maximum operating frequency of the electroacoustic transducer. The first filter can be a digital filter.

[0030] In the above technical solution, the output terminal of the single-phase full-bridge inverter is connected to the drive terminal of the electroacoustic transducer through an LC filter, and the input terminal of the single-phase full-bridge inverter is electrically connected to the output terminal of the DC power supply module.

[0031] By setting an LC filter, the harmonics generated during the inverter's inverter process can be filtered out.

[0032] Preferably, the LC filter includes a first capacitor and a first inductor; the two switches of one bridge arm of the single-phase full-bridge inverter have a first common connection terminal, and the two switches of the other bridge arm have a second common connection terminal; the first common connection terminal is electrically connected to one end of the first inductor, and the other end of the first inductor, one end of the first capacitor, and one drive terminal of the electroacoustic transducer are electrically connected to each other; the second common connection terminal, the other end of the first capacitor, and the other drive terminal of the electroacoustic transducer are electrically connected to each other.

[0033] In the above technical solution, the acoustic signal is a sound pressure signal or a sound intensity signal.

[0034] The present invention also provides an electroacoustic emission system, including an electroacoustic transducer and a single-phase full-bridge inverter connected to the drive terminal of the electroacoustic transducer, characterized in that the electroacoustic emission system further includes:

[0035] The first acquisition unit is used to acquire the acoustic signal output by the electroacoustic transducer.

[0036] The second acquisition unit is used to acquire the input current signal of the electroacoustic transducer;

[0037] The processor is configured to perform the steps of the control method of the electroacoustic emission system described above, wherein the output terminals of the first acquisition unit and the second acquisition unit are respectively connected to the processor.

[0038] In the above technical solution, the second acquisition unit is a current transformer.

[0039] The advantages and positive effects of this invention are: this invention uses the acoustic signal as the feedback object to achieve closed-loop control of the output of the electroacoustic transducer. In addition, multi-point sampling (i.e., sampling at multiple locations at the same distance from the sound source) is used to improve the accuracy of the feedback signal, thereby reducing the interference of environmental noise on the sampled signal. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 It is the equivalent circuit of an electroacoustic transducer in the prior art;

[0042] Figure 2 This is a simplified schematic diagram of the electroacoustic emission system structure according to an embodiment of this application;

[0043] Figure 3 yes Figure 2 Detailed structural diagram;

[0044] Figure 4 This is a control flowchart of the control method for the electroacoustic emission system according to an embodiment of this application;

[0045] Figure 5 This is a model of the acoustic transducer of an embodiment of this application;

[0046] Figure 6 This is a schematic diagram of the relevant signal waveforms of the electroacoustic transducer when the electroacoustic transducer model is accurately modeled, the electroacoustic emission system operates at 100Hz, and existing technical methods are used.

[0047] Figure 7 This involves comparing the output sound pressure waveform of the electroacoustic transducer with that of the system operating at 100Hz when there are deviations in the modeling of the electroacoustic transducer, using existing techniques, with that of the system without deviations.

[0048] Figure 8 This is a schematic diagram of the relevant signal waveforms of the electroacoustic transducer obtained by the control method of the electroacoustic emission system of this application when the electroacoustic emission system is operating at 100Hz.

[0049] Figure 9 This is a schematic diagram comparing the output sound pressure waveform of the electroacoustic transducer obtained by the electroacoustic emission system control method of this application with that without deviation when the modeling of the electroacoustic transducer model has a deviation and the electroacoustic emission system operates at 100Hz.

[0050] Figure 10 This is a schematic diagram of the transducer acoustic terminal sound pressure, electrical terminal voltage, and relative error waveforms between the target sound pressure and the actual output sound pressure, obtained by the control method of the electroacoustic emission system of this application when the electroacoustic emission system is operating in a frequency conversion state of 100Hz to 200Hz.

[0051] Figure 11 This is a schematic diagram of the transducer acoustic terminal sound pressure, electrical terminal voltage, and relative error waveforms between the target sound pressure and the actual output sound pressure, obtained by using the control method of the electroacoustic emission system of this application when the electroacoustic emission system is operating in a 100Hz-125Hz-150Hz frequency conversion state.

[0052] In the above attached figures:

[0053] 10. Electroacoustic transducer; 20. Controller; 30. Single-phase full-bridge inverter;

[0054] 1. First filter; 2. LC filter; 21. First capacitor; 22. First inductor; 3. Rectifier; 4. Driver; 5. First A / D converter; 6. Second A / D converter; 7. Current transformer; 8. AC power supply module. Detailed Implementation

[0055] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0056] This embodiment provides a control method for an electroacoustic emission system, which includes an electroacoustic transducer 10 and a single-phase full-bridge inverter 30 connected to the drive end of the electroacoustic transducer 10.

[0057] The control method includes: preset target acoustic signal value p ref Subtracting the acoustic signal output from the electroacoustic transducer 10 yields the first error signal p. ess The first error signal p ess After passing through the first controller, the reference current signal i is obtained. ref Reference current signal i ref Subtract the collected electroacoustic transducer input current signal i e The second error signal i is obtained ess The second error signal i ess After passing through the second controller, the obtained signal is modulated to obtain a PWM modulation signal, which is used to control the on / off state of the 30 switching transistors of the single-phase full-bridge inverter.

[0058] The first controller is a PR controller, and the second controller is one of a proportional controller, a PI controller, or a PID controller.

[0059] The electroacoustic transducer 10 outputs an acoustic signal that is the average value of acoustic signals detected at h different detection positions, and the distance between the acoustic radiation surface of the electroacoustic transducer 10 and each detection position is equal. In this embodiment, h ≥ 3.

[0060] The transfer function of the PR controller in the s-domain is expressed as follows:

[0061]

[0062] Where fa is the frequency of the output voltage signal of the single-phase full-bridge inverter 30, and k p1,fa k is the proportional coefficient of the PR controller corresponding to the frequency fa. r,fa ω is the resonant coefficient of the PR controller corresponding to the frequency fa. c This is the cutoff angular frequency of the PR controller.

[0063] The control method further includes: dividing the operating frequency band of the electroacoustic transducer 10 into K sub-frequency bands with the same frequency band width, where K ≥ 2;

[0064] If fa = f(k), then k p1,fa =k p1,f(k) k r,fa =k r,f(k) ; where k p1,f(k) k r,f(k) These correspond to the preset proportional coefficient and preset resonance coefficient corresponding to the frequency value f(k), respectively, k=0,1,……,K, f(0) and f(K) are the lower limit and upper limit of the working frequency band of the electroacoustic transducer 10, respectively, and f(1), f(2),……,f(K) are the upper limit values ​​of K sub-frequency bands, respectively;

[0065] Otherwise, if we determine that f(m) < fa < f(m+1), then we can calculate k using the following formula. p1,fs k r,fs :

[0066]

[0067]

[0068] Where △f=[f(K)-f(0)] / K, m is a natural number, 0≤m≤K-1.

[0069] The expression G of the transfer function of the first filter 1 in the s-domain LPF (s) is:

[0070]

[0071] Where τ is the time constant, τ=1 / (2×π×f) L ), f L >f max f max This is the maximum operating frequency of the electroacoustic transducer 10.

[0072] The output terminal of the single-phase full-bridge inverter 30 is connected to the drive terminal of the electroacoustic transducer 10 through the LC filter 2, and the input terminal of the single-phase full-bridge inverter 30 is electrically connected to the output terminal of the DC power supply module.

[0073] In a preferred embodiment, the LC filter 2 includes a first capacitor 21 and a first inductor 22; the two switches of one bridge arm of the single-phase full-bridge inverter 30 have a first common connection terminal A, and the two switches of the other bridge arm have a second common connection terminal B; the first common connection terminal A is electrically connected to one end of the first inductor 22, and the other end of the first inductor 22, one end of the first capacitor 21, and one drive terminal of the electroacoustic transducer 10 are electrically connected to each other; the second common connection terminal B, the other end of the first capacitor 21, and the other drive terminal of the electroacoustic transducer 10 are electrically connected to each other.

[0074] The acoustic signal is a sound pressure signal or a sound intensity signal.

[0075] The present invention also provides an electroacoustic emission system, the electroacoustic emission system including an electroacoustic transducer 10 and a single-phase full-bridge inverter connected to the drive end of the electroacoustic transducer 10.

[0076] Electroacoustic emission systems also include:

[0077] The first acquisition unit is used to acquire the acoustic signal output by the electroacoustic transducer 10.

[0078] The second acquisition unit is used to acquire the input current signal of the electroacoustic transducer 10;

[0079] The processor is configured to perform the steps of the control method of the above-described electroacoustic emission system, and the output terminals of the first acquisition unit and the second acquisition unit are both connected to the processor.

[0080] The second acquisition unit is a current transformer 7.

[0081] The AC power supply module 8 is electrically connected to the input terminal of the single-phase full-bridge inverter via the rectifier 3. The input current signal i from the electroacoustic transducer 10 is acquired via the current transformer 7. e The signal is converted into a digital signal by the first A / D converter 5.

[0082] The first acquisition unit (not shown in the figure) acquires the acoustic signal output by the electroacoustic transducer 10 (which may be a sound pressure signal in this embodiment), converts it into a digital signal through the second A / D converter 6, and then filters it through the first filter 1. In this embodiment, the first filter 1 is a digital filter.

[0083] To address the shortcomings of existing electroacoustic transmission systems that rely on empirical control or use sound field signals as feedback signals for indirect closed-loop control, and to further improve the performance of electroacoustic transmission systems for underwater communication and adapt to complex and ever-changing application scenarios, a dual closed-loop electroacoustic transmission system based on sound field signals was designed based on existing research.

[0084] Firstly, in terms of hardware circuitry, acoustic signals are introduced into the system as feedback, thereby achieving direct closed-loop control of the output signal. To reduce the interference of environmental noise on the sampled signal, multi-point sampling is employed to improve the quality of the acquired signal.

[0085] In addition, to improve the performance of the control system, the electrical input current is introduced as the inner loop control object to achieve dual closed-loop control.

[0086] A feedback control circuit consisting of sensors, analog-to-digital converters, and digital signal controllers was designed for this purpose.

[0087] Secondly, in terms of the control system, to balance the two important performance indicators of fast and error-free system response, two controllers were designed, including an outer-loop PR controller and an inner-loop PI controller. Finally, through experimental simulation, the rationality, effectiveness, and practical applicability of the proposed dual-closed-loop electroacoustic emission system based on sound field signals were verified from multiple aspects.

[0088] Based on the above analysis, it is necessary to analyze the changes in parameters related to the sound field signal, such as sound pressure and sound velocity of the electroacoustic transducer, starting from the sound end, in order to accurately reflect the actual output sound power of the electroacoustic transducer. Furthermore, by adjusting the input electrical power of the transmitting system according to the output magnitude, a closed-loop control system is formed to achieve real-time direct control of the sound power and maintain a stable output. Therefore, this invention proposes an electroacoustic transmitting system based on direct control of the sound field signal. This system uses the sound signal as the feedback object to achieve direct closed-loop control of the output. In addition, to reduce the interference of environmental noise on the sampling signal, multi-point sampling is used to improve the accuracy of the feedback signal. Based on this, the electrical input current is introduced as the inner loop control object to achieve dual closed-loop control, thereby improving the performance of the control system. Furthermore, to enable reliable operation of the system over a wide frequency range, a continuous PR control method is proposed. The above control system and method together constitute an electroacoustic transmitting system based on dual closed-loop control of the sound field signal.

[0089] Based on the above analysis, the electroacoustic transducer, as an electroacoustic conversion device, is modeled to analyze the conversion relationship from electrical signals to acoustic signals. For example... Figure 1 The figure shows the equivalent model of an electroacoustic transducer, with the eddy current resistance R at the electrical terminal. ES With the terminal eddy current inductor L ES All are nonlinear elements, R E The static resistance at the electrical terminal. The equivalent inductance L at the mechanical terminal. M Equivalent capacitance C M With equivalent resistance R M The acoustic impedance Z is obtained from the mechanical parameters of the electroacoustic transducer. AF This is determined by the working environment of the electroacoustic transducer.

[0090] Energy transfer and conversion are achieved between the electrical and acoustic terminals via a mechanical connection. According to equation (1), the magnitude of the output sound signal is related to the mechanical structure of the electroacoustic transducer and the magnitude of the current flowing through the electrical terminal. For a given electroacoustic transducer, its mechanical structure is fixed, and the corresponding parameters can be measured experimentally. Therefore, the quality of the sound signal emitted by the electroacoustic transducer is determined by parameters such as the magnitude and frequency of the system input current.

[0091]

[0092] In the formula, S D Let p be the area of ​​the transmitter end of the transducer, and u be the sound pressure level. m Let λ be the vibration velocity, Bl be the mechanical force coefficient, and i be the vibration velocity. e This represents the magnitude of the current flowing through the terminal.

[0093] However, due to the nonlinearity of the transducer's electrical impedance, it is impossible to accurately measure R. ES With LES Modeling is difficult because it's impossible to accurately describe the relationship between the input voltage and the current flowing through the transducer in an electroacoustic emission system, making direct current control very challenging. Furthermore, existing closed-loop control systems built using electrical signals calculate the sound field signal by combining the electrical signal flowing through the electrical terminal with the electroacoustic transducer model. However, the accuracy of the results is affected by the accuracy of the model, so using the sound field signal to build a closed-loop system for feedback regulation also faces challenges. Compared to using the electrical terminal current as the controlled object, directly using the sound pressure p at the acoustic terminal is more advantageous. With the continuous development of sensing technology, detecting sound pressure and converting it into an electrical signal using appropriate sensors is now quite mature. Directly acquiring the sound pressure level at the acoustic terminal can more accurately reflect the quality of the actual output sound signal of the electroacoustic emission system, while the electrical terminal current can only be approximated by model calculations.

[0094] like Figure 2 The diagram shows the structure of the electroacoustic emission system based on sound signals proposed in this invention. The power circuit mainly consists of an AC power supply, a rectifier circuit, an inverter circuit, a filter circuit, and an electroacoustic transducer. First, the rectifier circuit rectifies the AC power into DC power of a fixed voltage for easy control. Then, the inverter circuit converts the DC power back into AC power according to the amplitude and frequency of the AC power required by the load. The filter circuit filters out harmonics generated during the inverter process. The electroacoustic transducer converts the provided AC signal into a corresponding sound signal.

[0095] The control circuit mainly includes an analog-to-digital converter (AC / DC), a controller, a PWM signal generator, and a driver. The system uses the sound pressure level *p* at the sound terminal as the controlled object, acquiring the sound pressure level of the sound signal emitted by the electroacoustic emission system through corresponding sensors. Then, the analog-to-digital converter (ADC) converts the analog electrical signal into a digital signal that the digital controller can recognize. The controller then compares this signal with the target sound pressure level *p*. ref Together, calculations and analyses are performed to obtain the current reference signal i of the electrical input electroacoustic transducer. ref The obtained reference current signal is compared with the acquired current signal i. e Further analysis and calculations yielded a corresponding control strategy to adjust the input electrical signal and correct the error between the output sound signal and the target sound signal. The controller outputs the control strategy as a PWM signal, and the driver generates a drive current based on the PWM signal to control the switching on and off of each power device in the inverter.

[0096] The rationality of the control system design directly determines the performance of the electroacoustic emission system, such as... Figure 3 The diagram shown is of the broadband dual-closed-loop control system based on acoustic signals proposed in this invention. ref For the reference sound pressure signal, i refAs the reference current signal, G1(s) is the outer loop controller for sound pressure, G2(s) is the inner loop controller for current, and L... a For the filter inductor, C a For the filter capacitor, C dc The capacitor is on the DC side. G1(s) is the PR controller, G2(s) is the PI controller, and p1, p2, and p3 represent the sound pressure levels at equidistant but different locations from the sound source of the electroacoustic transducer. The control system first uses a first filter (which can be a digital filter) to filter the acquired sound pressure signal, removing high-frequency noise. The transfer function of the first filter is:

[0097]

[0098] In the formula, τ is the time constant.

[0099] The time constant determines the filter's cutoff frequency f. L Typically, the cutoff frequency is required to be greater than the fundamental frequency of the sound pressure signal, i.e., (f L >f max ), f max This is the maximum operating frequency of the electroacoustic transducer.

[0100]

[0101] The filtered sound pressure needs further processing to obtain the real-time sound pressure signal p:

[0102]

[0103] In the formula, These correspond to the filtered signals of the acquired sound pressure levels p1, p2, and p3, respectively. In practical applications, researchers can adjust the number of acquired sound pressure signals according to actual needs.

[0104] This invention calculates the real-time sound pressure signal of the electroacoustic transducer against the target value, and the resulting error signal is input to a PR controller for processing to obtain an outer-loop reference current signal. To improve the system's output performance, a PI controller is introduced as the inner-loop controller based on the PR controller. The reference current signal obtained from the outer-loop control system is calculated against the terminal current, and the resulting error current signal is input to the inner-loop PI controller, thus obtaining the final controller control strategy. The control signal is pulse-width modulated to generate a PWM signal to adjust the output of the inverter circuit in real time. The transfer function of the PR controller is as follows:

[0105]

[0106] The transfer function of the PI controller in the s-domain is expressed as:

[0107]

[0108] In the formula, k p1,fa is the proportionality coefficient of the PR controller corresponding to the frequency fa, and k r,fa is the resonant coefficient of the PR controller corresponding to the frequency fa, and ω c is the cut-off angular frequency of the PR controller, and ω s = 2×π×fa is the resonant angular frequency; k p2 is the proportionality coefficient of the PI controller, and k i is the integral coefficient of the PI controller.

[0109] Since the PR controller only has a large gain near the resonant frequency, it can ensure that the dual closed-loop electro-acoustic emission system based on the acoustic signal proposed in the present invention can track the target acoustic signal without static error. However, the electro-acoustic emission system usually operates in a relatively wide frequency range. Therefore, the present invention proposes a continuous PR control method. In the control system of the present invention, the resonant angular frequency ω s should be used as a variable, and its value changes with the operating frequency of the electro-acoustic emission system. That is, ω s = 2×π×fa, where fa is the real-time operating frequency of the electro-acoustic emission system (i.e., the output signal frequency of the single-phase full-bridge inverter 30). Secondly, for the controller parameter values at each operating frequency, they are realized by the following method:

[0110] First, assume that the operating frequency band of the transducer is f(0)~f(K), and it is evenly divided into K segments according to the accuracy requirements, that is, the width of each segment is △f = [f(K)-f(0)] / K.

[0111]

[0112] For the operating frequency fa of the transducer, first determine the frequency band it belongs to, and then calculate its controller parameters k p1,fa and k<00000​​​​​​​​​​​​​The method described above for determining the PR controller coefficients avoids the need for experimental determination of the coefficients at every frequency point, which greatly increases the design difficulty of the controller. On the other hand, existing technologies simply divide the controller coefficients into several segments, with the controller value remaining unchanged within each frequency segment. This can lead to a significant decrease in the controller gain at frequencies deviating from the resonant point. This proposed solution effectively addresses this problem.

[0116] For the proportionality coefficient k corresponding to the frequency f(k) p1,f(k) , resonance coefficient k r,f(k) This can be determined through experiments or simulations, as those skilled in the art will understand.

[0117] Figure 4 This is a flowchart of the control method for the electroacoustic emission system proposed in this invention. First, the relevant parameters of the target output acoustic signal of the electroacoustic emission system are set, including the sound pressure signal p. ref The sensor samples the sound pressure p of the sound signal output from the acoustic transducer's acoustic terminal and converts it into an analog electrical signal. Then, the analog-to-analog converter (DAC) converts the analog signal into a digital signal. This digital signal is input into a digital signal processor (DSP), where it is compared with the sound pressure of the target acoustic signal to obtain the error signal p. ess The DSP calculates the parameters of the PR controller based on the current operating frequency. The PR controller then processes the error signal to obtain the reference current i for the inner loop control. ref Simultaneously, the current transformer inputs a current signal i to the electrical terminal of the electroacoustic transducer. e The analog-to-digital converter (ADC) performs sampling and converts the analog electrical signal into a digital signal; the PI controller calculates the error i between the reference current signal and the actual current signal. ess The system outputs the final control signal; this control signal is compared with a triangular carrier signal to obtain a PWM control signal; the driver then generates a gate drive current based on the PWM signal, which controls the switching on and off of various power devices in the inverter, causing the inverter to output the target AC signal; finally, this signal, after being filtered by a filter circuit to remove harmonics, provides power to the electroacoustic transducer, enabling it to output the target acoustic signal. After completing one working cycle, the sensor continues to collect the sound pressure p, entering the next working cycle, until the system stops operating.

[0118] It should be noted that in this embodiment, the sound pressure signal output by the electroacoustic transducer is used as the sound signal, and the preset target sound signal value p ref The preset target sound pressure level (i.e., the desired output sound pressure level of the electroacoustic transducer) is used. Those skilled in the art can also collect sound intensity signals as the target signal or reference signal, i.e., the preset target sound signal value p. ref The preset target sound intensity value.

[0119] Simulation verification

[0120] To demonstrate the performance of the proposed broadband dual-closed-loop electroacoustic emission system based on acoustic signals, an experimental simulation system was built. The relevant parameter values ​​are shown in Table 1. (Transducer terminal eddy current resistance R...) ES With eddy current inductor L ES The expression is shown below.

[0121] R ES =L E ω x cosθ, where 0 <x<1 (10)

[0122] L ES =L E ω x-1 sinθ (11)

[0123]

[0124] In the formula, θ is the first phase angle value, and L E y is the proportionality coefficient, x is the first coefficient, and y is the second coefficient.

[0125] Transducer acoustic end model as follows Figure 5 As shown, the calculation formulas for each component are as follows.

[0126]

[0127]

[0128]

[0129]

[0130] In the formula, a is the radiation radius of the transducer's acoustic end, c is the sound velocity, and ρ is the medium density.

[0131] Table 1. Relevant parameters of the electroacoustic transducer model.

[0132] Parameter name Value Parameter name Value <![CDATA[U dc ]]> 5V <![CDATA[R M ]]> 3N·s / m <![CDATA[S D ]]> <![CDATA[0.033329m 2 ]]> <![CDATA[R E ]]> 7.4Ω Bl 11.361 N / A <![CDATA[L E ]]> 0.0439H <![CDATA[C M ]]> 3.099mm / N n 0.9 <![CDATA[L M ]]> 0.034089kg ρ <![CDATA[1.2kg / m 3 ]]> c 343m / s a 0.103m

[0133] First, the rationality of the proposed electroacoustic emission system is analyzed, and a closed-loop control system with electrical signals as control signals is constructed, using a PI controller. At time zero, the system's target sound pressure amplitude is set to 8 Pa and the operating frequency to 100 Hz. Figure 6 For an electroacoustic emission system operating at 100Hz with an accurate transducer model (accurate model parameters), a closed-loop control system using electrical signals is constructed, analyzing the transducer's input voltage, voltage error, and output sound pressure signal waveform. It can be seen that at a fixed operating frequency, this control system can guarantee a stable output, with the voltage error remaining within 5 × 10⁻⁶. -3Below V. To illustrate the output of this method when the model has biases, based on the data in Table 1, the eddy current resistance R of the transducer terminal is artificially increased. ES Increasing the value by 1Ω, the eddy current inductance L ES The value is increased by 2mH to simulate the deviation between the transducer model and the actual transducer. When the electroacoustic transducer model is inaccurate and has deviations, its output sound pressure is compared with that when there is no deviation. Figure 7 As shown. Figure 7 In the image, the blue waveform represents the waveform when the electroacoustic transducer model is accurately modeled, while the red waveform represents the waveform when the electroacoustic transducer model is inaccurate. According to... Figure 7 When the model is inaccurate, the actual sound pressure output of the electroacoustic transducer is only 7.3 Pa, which is 0.7 Pa lower than the target sound pressure. This indicates that when a closed-loop control system is constructed using only electrical signals as feedback signals, if the electroacoustic transducer model is inaccurate and cannot accurately depict the actual output characteristics of the transducer, it is impossible to effectively control the acoustic signal output of the electroacoustic transducer.

[0134] Figure 8 To implement the control method of the electroacoustic emission system proposed in this invention, under the same sound pressure output target (8 Pa), the output sound pressure, sound pressure error, and input voltage signal waveform of the electroacoustic transducer are analyzed. Figure 8 It can be seen that the output sound pressure of the electroacoustic emission system of this application is basically consistent with the target sound pressure output. Figure 9 In the table, the blue waveform represents the waveform when the electroacoustic transducer model is accurately modeled, and the red waveform represents the waveform when the electroacoustic transducer model is inaccurate (i.e., based on the data in Table 1, the eddy current resistance R of the transducer terminal is artificially increased). ES Increasing the value by 1Ω increases the eddy current inductance L. ES The value increases by 2mH). From Figure 9 It can be seen that even if the electroacoustic transducer model is inaccurate and has deviations, since the control method of this application targets the sound pressure at the acoustic end, it is not affected by the modeling accuracy. Therefore, the output sound pressure obtained according to the control method of this application is almost the same as when the modeling is accurate and without deviation (i.e., Figure 9 In the sound pressure waveform diagram, the blue and red waveforms basically overlap. According to... Figure 7 and Figure 8 Comparative analysis shows that the electroacoustic emission system of the present invention can effectively ensure that the amplitude and frequency of the output signal are consistent with the target signal. There is a small relative error between the actual output sound signal and the target sound signal, which shows that the electroacoustic emission system designed in this invention can effectively ensure the consistency between the transducer output sound signal and the target signal.

[0135] In practical applications, electroacoustic transmission systems typically operate in frequency conversion mode when transmitting information. To verify the system's performance in frequency conversion mode, it is necessary to analyze the system's output sound signal when the operating frequency changes. For example... Figure 10 The figure shows the waveforms of the transducer's acoustic terminal sound pressure, electrical terminal voltage, and the relative error between the target sound pressure and the actual output sound pressure when the electroacoustic emission system switches from 100Hz to 150Hz (frequency switching at 0.1s). As can be seen from the sound pressure waveform, when the system switches frequencies at 0.1s, the output signal frequency of the electroacoustic transducer rapidly switches from 100Hz to 150Hz, and the sound pressure amplitude does not subsequently experience significant overshoot, with the maximum value remaining around 8Pa. Similar to the sound pressure signal, the transducer's electrical terminal voltage quickly reaches a new steady state after the frequency switch. It can be seen that when switching at different frequency points, the system can quickly restore the output to a new stable state. The above simulation results further demonstrate that the electroacoustic emission system designed in this invention has good practical application value.

[0136] To verify the effectiveness of the continuous PR controller (i.e., formulas (7)-(9)) proposed in this invention, in Figure 10 Based on the designed frequency converter operation simulation, 125Hz was added as the operating frequency point. For example... Figure 11 As shown, the output signal frequency of the electroacoustic transducer is switched from 100Hz to 125Hz (frequency switching at 0.1s), and finally to 150Hz (frequency switching at 0.2s). The proportional gain k of the PR controller is shown at 100Hz. p With the PR controller resonance coefficient k r When the values ​​of k are 80, 100, and 150Hz respectively p With k r If the values ​​are 90 and 120 respectively, then according to formulas (8) and (9), the PR controller parameter k at 125Hz can be calculated. p With k r The values ​​are 85 and 110, respectively. The waveforms of the transducer's acoustic terminal sound pressure, electrical terminal voltage, and the relative error between the target sound pressure and the actual output sound pressure are shown below. Figure 11 As shown in the figure, it can be seen that when the frequency switches from 100Hz to 125Hz, the sound pressure amplitude remains at 8Pa. Even when the frequency rapidly switches to 125Hz, the relative error of the sound pressure remains approximately 5×10⁻⁶. -3 Within Pa. The situation is basically similar when the frequency switches from 125Hz to 150Hz. It can be seen that the continuous PR controller proposed in this invention can effectively achieve arbitrary frequency adjustment while maintaining essentially unchanged stability. The above simulation results further demonstrate that the electroacoustic emission system and its control method of this invention have good practical application value.

[0137] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0138] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention should still fall within the scope of this patent. After reading this invention, any modifications of the present invention in various equivalent forms by those skilled in the art fall within the scope defined by the appended claims. Unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

Claims

1. A control method for an electroacoustic emission system, the electroacoustic emission system comprising an electroacoustic transducer (10) and a single-phase full-bridge inverter (30) connected to the drive end of the electroacoustic transducer (10). Its features are: The control method includes: preset target acoustic signal value p ref The first error signal is obtained by subtracting the acoustic signal output from the electroacoustic transducer (10). p ess First error signal p ess The reference current signal is obtained after passing through the first controller. i ref Reference current signal i ref Subtract the collected electroacoustic transducer input current signal i e Obtain the second error signal i ess Second error signal i ess The signal obtained by the second controller is modulated by PWM to obtain a PWM modulation signal, and the PWM modulation signal is used to control the switching of the single-phase full-bridge inverter (30). The first controller is a PR controller, and the second controller is one of a proportional controller, a PI controller, and a PID controller; The transfer function of the PR controller is in s The expression for the domain is: ； in, fa The frequency of the output voltage signal of the single-phase full-bridge inverter (30) is... k p1,fa For frequency fa The corresponding proportional gain of the PR controller, k r,fa For frequency fa The corresponding resonant coefficient of the PR controller, ω c This is the cutoff angular frequency of the PR controller; The control method further includes: dividing the operating frequency band of the electroacoustic transducer (10) into... K Sub-bands with the same bandwidth K ≥2; like fa = f ( k ),but ;in, These correspond to the frequency values ​​respectively. f ( k The corresponding preset proportional coefficient and preset resonance coefficient, k =0,1,……, K , f (0) f ( K The values ​​are the lower and upper limits of the operating frequency band of the electroacoustic transducer (10), respectively. f (1) f (2), ... f ( K ) respectively correspond to K The upper limit of each sub-band; Otherwise, if f ( m )< fa < f ( m +1), then calculate using the following formula. : ； ； Among them, △ f= [ f ( K )- f (0)] / K , m For natural numbers, 0 ≤ m ≤ K -1.

2. The control method according to claim 1, characterized in that: The acoustic signal output by the electroacoustic transducer (10) is in h The average value of the acoustic signals detected at different detection positions, wherein the distance between the sound source point of the electroacoustic transducer (10) and each detection position is equal.

3. The control method according to claim 1 or 2, characterized in that: The output terminal of the single-phase full-bridge inverter (30) is connected to the drive terminal of the electroacoustic transducer (10) through an LC filter (2), and the input terminal of the single-phase full-bridge inverter (30) is electrically connected to the output terminal of the DC power supply module.

4. The control method according to claim 3, characterized in that: The LC filter (2) includes a first capacitor (21) and a first inductor (22); the two switches of one bridge arm of the single-phase full-bridge inverter (30) have a first common connection terminal (A), and the two switches of the other bridge arm have a second common connection terminal (B); the first common connection terminal (A) is electrically connected to one end of the first inductor (22), and the other end of the first inductor (22), one end of the first capacitor (21), and one drive end of the electroacoustic transducer (10) are electrically connected to each other; the second common connection terminal (B), the other end of the first capacitor (21), and the other drive end of the electroacoustic transducer (10) are electrically connected to each other.

5. The control method according to claim 1 or 2, characterized in that: The acoustic signal is a sound pressure signal or a sound intensity signal.

6. An electroacoustic emission system, comprising an electroacoustic transducer (10) and a single-phase full-bridge inverter (30) connected to the drive end of the electroacoustic transducer (10), characterized in that, The electroacoustic emission system also includes: The first acquisition unit is used to acquire the acoustic signal output by the electroacoustic transducer (10); The second acquisition unit is used to acquire the input current signal of the electroacoustic transducer (10); A processor configured to perform the steps of the control method for the electroacoustic emission system according to any one of claims 1-5, wherein the output terminals of the first acquisition unit and the second acquisition unit are respectively connected to the processor.

7. The electroacoustic emission system according to claim 6, characterized in that: The second acquisition unit is a current transformer (7).

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