Method and apparatus for expanding bandwidth of electroacoustic transducer with active impedance matching circuit

Abstract

The present invention provides a method and device for expanding the bandwidth of an electroacoustic transducer with an active impedance matching circuit. The method for expanding the bandwidth of the electroacoustic transducer includes: constructing a closed-loop control system, and making the expression of the output current reference value in the s domain be I ac_ref (s) = -V m (s) / (m f ×jX f (s)), where m f is the matching degree corresponding to the point with the maximum sound power among the points of the surface corresponding to the frequency f. The surface is the surface of the relationship between the sound power and the operating frequency and the matching degree m of the electroacoustic transducer in the oxyz coordinate system. The adjusted model is a model obtained by adjusting the equivalent model of the electroacoustic transducer; the adjustment of the equivalent model of the electroacoustic transducer is specifically: modifying the reactance value of the reactance of the electrical terminal structure at the reactance value corresponding to the operating frequency f of the electroacoustic transducer.

Description

Technical Field

[0001] The present invention relates to the technical fields of power electronics and underwater acoustic communication, and relates to a method and device for expanding the bandwidth of an electro-acoustic transducer with an active impedance matching circuit. Background Art

[0002] As the only known signal that can achieve long-distance transmission in water at present, acoustic wave signals are widely used in underwater mapping, seabed energy exploration, military and other fields. As a crucial part of underwater communication, an electro-acoustic transducer mainly realizes the conversion of electrical signals into acoustic wave signals. With the continuous deepening of ocean development, the requirements for sonar systems are constantly increasing. On the one hand, broadening the transducer bandwidth can improve the reliability and stability of transmission performance when transmitting signals. On the other hand, it enables the transducer to transmit more information. Therefore, in order to better adapt to the complex underwater environment, the bandwidth requirements for electro-acoustic transducers are constantly increasing. It is urgent to improve the performance of electro-acoustic transducers to meet the demand for broadband acoustic wave signals. Studying how to increase the bandwidth of electro-acoustic transducers has important practical significance. For a certain electro-acoustic transducer, from a theoretical perspective, a higher bandwidth means a lower quality factor. Electro-acoustic transducers are also restricted by the bandwidth-gain-volume theory. Blindly selecting the geometric dimensions of each part of the transducer just for the one-sided pursuit of a low quality factor will affect other performances of the transducer, such as the radiated acoustic power.

[0003] According to the basic theory of transducers, the bandwidth of a transducer is determined by its quality factor, including the electrical quality factor and the mechanical quality factor. The mechanical quality factor is not only related to materials, mechanical losses and radiation impedance, but also has a close relationship with the structural parameters of the transducer. Therefore, by designing the structure of each part of the transducer, the purpose of reducing the mechanical quality factor can be achieved. A large number of studies are based on the multi-modal principle to attach an impedance matching layer to the front radiation head of the transducer to broaden its bandwidth. This method realizes bandwidth expansion by changing the parameters of the transducer itself, but it is only applicable to the hardware design stage of the transducer. For existing transducer devices, compared with the mechanical quality factor, its electrical quality factor is easier to change. Therefore, the present invention intends to expand the bandwidth of the transducer by impedance matching and adjusting the quality factor of the transducer.

[0004] Existing research on transducer impedance matching mainly focuses on how to eliminate reactance, so as to improve the active output ability of electro-acoustic transducers within the working bandwidth. Currently, the main impedance matching methods for transducers are static impedance matching and dynamic impedance matching methods, but both of these methods have the problem that they cannot achieve good impedance matching across the entire working frequency band of the transducer.

[0005] Some studies have proposed an active impedance matching method, which has obvious advantages over traditional passive impedance matching and can effectively solve the problems of passive impedance matching. However, existing active impedance matching is based on the idea of reactive power compensation in power systems. It mainly improves the active output of the system within the bandwidth of the transducer, that is, directly equivalent the transducer to a load composed of a resistor and an inductor, and compensates the reactive power generated by the inductive load through the instantaneous reactive power theory, that is, completely cancels the reactive power, so as to achieve the maximum active output of the transducer. However, from the perspective of the actual application of the transducer, although this method compensates the reactive power of the inductive load to the greatest extent, it does not effectively improve the bandwidth, which limits the performance of the transducer in actual applications. Summary of the Invention

[0006] Aiming at the problem that the existing active impedance matching method does not effectively improve the bandwidth, which limits the performance of the transducer in actual applications, the present invention provides an electroacoustic transducer bandwidth expansion device and method.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is: an electroacoustic transducer bandwidth expansion method with an active impedance matching circuit, the active impedance matching circuit includes a single-phase full-bridge inverter connected to the driving end of the electroacoustic transducer; two switching tubes of one bridge arm of the single-phase full-bridge inverter have a first common connection end, and two switching tubes of the other bridge arm have a second common connection end; two input ends of the single-phase full-bridge inverter are respectively and correspondingly electrically connected to two output ends of the DC power supply module; the first common connection end is electrically connected to the first end of the first inductor, and the second common connection end, the first end of the first capacitor, and one driving end of the electroacoustic transducer are electrically connected to each other; the second end of the first inductor, the second end of the first capacitor, and one output end of the power amplifier are electrically connected to a first electrical connection point, and the other output end of the power amplifier and the other driving end of the electroacoustic transducer are electrically connected to each other;

[0008] The equivalent model of the electroacoustic transducer is sequentially coupled by an electrical end structure, a mechanical end structure, and an acoustic end structure; the electrical end structure includes a static equivalent resistor and an eddy current equivalent structure connected in series between two input ends of the electroacoustic transducer;

[0009] The electroacoustic transducer bandwidth expansion method includes:

[0010] When the operating frequency of the electroacoustic transducer is f, let the reference value of the output current The expression I ac_ref (s) in the s domain is where s represents the variable of the s-domain function; V m (s) is the difference between the measured voltage at the second end of the first capacitor and the voltage at the first end of the first capacitor The expression in the s domain, Xf (s) is X f Expression in the s-domain, X f is the imaginary part of the impedance of the eddy current equivalent structure when the operating frequency of the electro-acoustic transducer is f;

[0011] Apply I ac_ref (s) through a proportional controller to obtain the feedforward voltage reference value V ac_f (s); I ac_ref Subtract I ac (s) from I ac to obtain the current error signal ΔI ac The result obtained after the current error signal ΔI ac_f passes through a PR controller is added to the feedforward voltage reference value V

[0012] wherein, I ac (s) is the measured value of the output current of the power amplifier Expression in the s-domain, m f is the matching degree corresponding to the point with the maximum acoustic power among the points on the surface corresponding to the frequency f;

[0013] The surface is the surface of the relationship between P AR,f,m ' and the operating frequency of the electro-acoustic transducer and the matching degree m in the oxyz coordinate system;

[0014] wherein, in the constructed oxyz coordinate system, o is the coordinate origin, the x-axis represents the frequency, the y-axis represents the matching degree m, the z-axis represents the acoustic power, and P AR,f,m ' represents the acoustic power corresponding to the adjusted model when the operating frequency of the electro-acoustic transducer is f and the matching degree is m. The value range of m is [0,1], and the value range of f is [f L , f H , f L , f H are respectively the minimum operating frequency and the maximum operating frequency of the electro-acoustic transducer;

[0015] The adjusted model is a model obtained by adjusting the equivalent model of the electro-acoustic transducer; the adjustment of the equivalent model of the electro-acoustic transducer is specifically: modifying the reactance value X f of the reactance of the electrical terminal structure at the operating frequency f of the corresponding electro-acoustic transducer to (1 - m)X f .

[0016] In the present invention, let the output current reference value Expression in the s-domain I ac_ref (s) is wherein, m fis a matching degree value in the range of [0, 1] obtained according to the surface. In this solution, let the value of the matching degree m vary within the range of [0, 1], and let the value of f vary within the value range of [f L , f H . According to the adjusted model, obtain the sound power values corresponding to different m values and different f values. Take the point with the maximum sound power among the points on the surface corresponding to each frequency f as the matching degree m corresponding to the corresponding frequency f f . That is, in this application, increase the sound power values corresponding to each frequency point, so that in the response curve of the electro-acoustic transducer with an active impedance matching circuit, the frequency difference between the two frequency points when the sound power is less than the maximum sound power response by 3 dB increases (that is, the frequency value of the smaller frequency point among the two frequency points is less than the frequency value of the corresponding smaller frequency point in the original curve, and the frequency value of the larger frequency point among the two frequency points is greater than the frequency value of the corresponding larger frequency point in the original curve), thereby increasing the bandwidth of the transducer.

[0017] In the present invention, the active impedance matching circuit only compensates the reactance part of the eddy current equivalent structure, that is, only compensates the reactive power, so that the present invention can ensure that the maximum sound power value remains unchanged without injecting active power into the system where the transducer is located.

[0018] In the present invention, by subtracting the measured value from the target matching value, the modulation feedback amount is calculated, so that closed-loop control can be realized, and the control accuracy is higher. The bandwidth broadening method of the present invention can track the inductance value of the eddy current equivalent inductance of the transducer, and calculate the output current reference value according to the inductance value of the eddy current equivalent inductance at the corresponding operating frequency, so that it can avoid being processed only at a single frequency and is applicable to the entire operating frequency range.

[0019] In the above technical solution: the eddy current equivalent structure is a series structure composed of an eddy current equivalent inductance and an eddy current equivalent resistance in series, X f = ωL ES,f ; or

[0020] the eddy current equivalent structure is a parallel structure composed of an eddy current equivalent inductance and an eddy current equivalent resistance in parallel, X f = Im(Z ES,f );

[0021] where Im(Z ES,f ) represents the imaginary part of Z ES,f , Z ES,f represents the impedance of the eddy current equivalent structure when the operating frequency of the electro-acoustic transducer is f, R ES,f , L ES,fThey respectively correspond to the inductance value of the eddy current equivalent inductance and the resistance value of the eddy current equivalent resistance when the operating frequency of the electroacoustic transducer is f. j represents the imaginary unit, and ω = 2πf.

[0022] In the above technical solution:

[0023]

[0024] Among them, Z AM ' = Z AM Z AF ' = Z AF ;

[0025] Among them, Z AE ' represents the equivalent impedance after the impedance of the electrical terminal structure of the adjusted model when the operating frequency of the electroacoustic transducer is f and the matching degree is m is converted to the acoustic terminal structure. Z AM ', Z AF ' respectively represent the equivalent impedance after the impedance of the mechanical terminal structure of the adjusted model is converted to the acoustic terminal structure and the impedance of the acoustic terminal structure of the adjusted model. Z AM Z AF respectively represent the equivalent impedance after the impedance of the mechanical terminal structure of the equivalent model of the electroacoustic transducer is converted to the acoustic terminal structure and the impedance of the acoustic terminal structure of the equivalent model of the electroacoustic transducer. S d represents the equivalent radiation area of the electroacoustic transducer, and Bl represents the electromechanical coupling factor of the electroacoustic transducer. represents the output voltage of the power amplifier. represents the modulus value of.

[0026] In the present invention, by converting the electrical terminal structure and the mechanical terminal structure of the adjusted model to the acoustic terminal, it is convenient to calculate the acoustic power.

[0027] In the above technical solution:

[0028] When the eddy current equivalent structure is a series structure composed of a series connection of an eddy current equivalent inductance and an eddy current equivalent resistance:

[0029] Or

[0030] When the eddy current equivalent structure is a parallel structure composed of a parallel connection of an eddy current equivalent inductance and an eddy current equivalent resistance:

[0031]

[0032] R E represents the resistance value of the static equivalent resistance.

[0033] In the above technical solution, the mechanical end structure includes a dynamic resistor, a dynamic inductor, and a dynamic capacitor connected in series with each other;

[0034]

[0035] Among them, R AM 、L AM 、C AM respectively represent the resistance value of the dynamic resistor, the inductance value of the dynamic inductor, and the capacitance value of the dynamic capacitor after being converted to the acoustic end. R M 、L M 、C M respectively represent the resistance value of the dynamic resistor, the inductance value of the dynamic inductor, and the capacitance value of the dynamic capacitor.

[0036] In the above technical solution, when the operating frequency of the electro-acoustic transducer is f, the transfer function G PR,f (s) of the PR controller in the s-domain is:

[0037]

[0038] Among them, k p,f 、k r,f are respectively the proportional coefficient and the resonance coefficient of the PR controller, and ω c is the cut-off angular frequency of the PR controller.

[0039] In the above technical solution, adjust the value of m within the range [0, 1], adjust the value of f within the range [f L , f H , and calculate the corresponding value of P AR,f,m ', so as to obtain the surface.

[0040] The present invention also provides an electro-acoustic transducer bandwidth expansion device, including a processor, and the processor is configured to execute the above electro-acoustic transducer bandwidth expansion method.

[0041] Compared with the prior art, the present invention has the following advantages: The present invention combines the active impedance matching theory and the transducer bandwidth expansion principle. Without changing the maximum acoustic power of the transducer, by partially or fully matching the eddy current equivalent inductance at the electrical end (determined by the specific matching degree value), while maximizing the bandwidth of the transducer, it is also possible to compensate for the reactance part of the eddy current equivalent structure that generates reactive power, and increase the active output of the power amplifier as much as possible. According to the present application, the bandwidth of the electro-acoustic transducer can be further expanded while ensuring the acoustic power output, and the problem of the reduction of the maximum acoustic power of the transducer during bandwidth expansion can also be avoided. Description of the Drawings

[0042] Figure 1is an equivalent model of an electroacoustic transducer in the prior art targeted by Embodiment 1 of the present invention;

[0043] Figure 2 is for Figure 1 a schematic diagram of the adjusted model obtained from the model;

[0044] Figure 3 is to Figure 2 the model obtained by converting the electrical terminal structure and mechanical terminal structure of the adjusted model to the acoustic terminal structure;

[0045] Figure 4 is a schematic connection diagram of the active impedance matching circuit in Embodiment 1 of the present invention and Figure 1 the equivalent model of the electroacoustic transducer shown;

[0046] Figure 5 is a schematic diagram of the acoustic terminal structure in the equivalent model of the existing loudspeaker targeted by Embodiment 1 of the present invention;

[0047] Figure 6 is a control block diagram of the electroacoustic transducer bandwidth expansion device in Embodiments 1 and 2 of the present invention;

[0048] Figure 7 is another equivalent model of an electroacoustic transducer in the prior art targeted by Embodiment 2 of the present invention;

[0049] Figure 8 is for Figure 7 a schematic diagram of the adjusted model obtained from the model;

[0050] Figure 9 is to Figure 8 the model obtained by converting the electrical terminal structure and mechanical terminal structure of the adjusted model to the acoustic terminal structure;

[0051] Figure 10 is a schematic connection diagram of the active impedance matching circuit in Embodiment 2 of the present invention and Figure 7 the equivalent model of the electroacoustic transducer shown;

[0052] Figure 11 is a schematic diagram of the steps of the electroacoustic transducer bandwidth expansion method in the embodiments of the present invention;

[0053] Figure 12 is a schematic representation of the electroacoustic transducer bandwidth in the operating frequency - acoustic power curve;

[0054] Figure 13 is a schematic diagram of the relationship between the acoustic power and frequency corresponding to the equivalent model of the existing electroacoustic transducer in Embodiment 1 of the present invention;

[0055] Figure 14It is a schematic diagram of the relationship between the matching degree parameter, sound power, and bandwidth and the optimal matching curve in Embodiment 1 of the present invention;

[0056] Figure 15 It is the optimal impedance matching curve obtained in Embodiment 1 of the present invention;

[0057] Figure 16-1 、 Figure 16-2 、 Figure 16-3 They are the simulation experiment results when the operating frequency range of the electroacoustic transducer in Embodiment 1 of the present invention is 150Hz - 250Hz, 250Hz - 350Hz, and 350Hz - 450Hz. Detailed implementation manners

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will describe the embodiments of the present invention in combination with the accompanying drawings through specific embodiments, and clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0059] Embodiment 1

[0060] As Figure 4 shown, the present invention provides a method for expanding the bandwidth of an electroacoustic transducer with an active impedance matching circuit. The active impedance matching circuit includes a single-phase full-bridge inverter 30 connected to the driving end of the electroacoustic transducer 10; two switching tubes of one bridge arm of the single-phase full-bridge inverter 30 have a first common connection end A, and two switching tubes of the other bridge arm have a second common connection end B; two input ends of the single-phase full-bridge inverter 30 are respectively electrically connected to two output ends of the DC power supply module 4; the first common connection end A is electrically connected to the first end of the first inductor 2, and the second common connection end B, the first end of the first capacitor 1, and a driving end of the electroacoustic transducer 10 are electrically connected to each other; the second end of the first inductor 2, the second end of the first capacitor 1, and an output end of the power amplifier are electrically connected to a first electrical connection point P1, and the other output end of the power amplifier and the other driving end of the electroacoustic transducer 10 are electrically connected to each other.

[0061] The equivalent model of the electroacoustic transducer is sequentially coupled by an electrical end structure, a mechanical end structure, and an acoustic end structure; the electrical end structure includes a static equivalent resistance and an eddy current equivalent structure connected in series between two input ends of the electroacoustic transducer.

[0062] The identification of the equivalent model of the electroacoustic transducer, its specific structure, and specific structure parameters (including the relational expressions between the eddy current equivalent resistance, eddy current equivalent inductance, and frequency) are prior arts in the field.

[0063] As Figure 6 、 Figure 11 shown, the method for expanding the bandwidth of the electroacoustic transducer includes: constructing a closed-loop control system. In the closed-loop control system, when the operating frequency of the electroacoustic transducer is f, the output current reference value in the s-domain is expressed as I ac_ref (s) is where s represents the variable of the s-domain function; V m (s) is the expression in the s-domain of the difference between the voltage at the second terminal of the first capacitor and the voltage at the first terminal of the first capacitor measured in the s-domain, X f (s) is the expression of X f in the s-domain, X f is the imaginary part of the impedance of the eddy current equivalent structure when the operating frequency of the electroacoustic transducer is f.

[0064] Pass I ac_ref (s) through a proportional controller to obtain the feedforward voltage reference value V ac_f (s); Subtract I ac_ref (s) from I ac (s) to obtain the current error signal ΔI ac , and add the result obtained after passing the current error signal ΔI ac through a PR controller to the feedforward voltage reference value V ac_f (s), and perform PWM modulation on the added result to obtain the duty cycle signal of the switching tubes of the single-phase full-bridge inverter 30.

[0065] The proportional coefficient k pwm is the ratio of the output voltage signal of the inverter bridge of the single-phase full-bridge inverter 30 to the input signal of the PWM module, that is, the gain. The operating frequency of the electroacoustic transducer is the frequency of the output voltage signal of the power amplifier.

[0066] I ac (s) is the expression in the s-domain of the measured value of the output current of the power amplifier . m f is the matching degree corresponding to the point with the maximum acoustic power among the points on the surface corresponding to the frequency f;

[0067] The surface is the surface of the relationship between P AR,f,m ' and the operating frequency of the electroacoustic transducer and the matching degree m in the oxyz coordinate system. Adjust the value of m within the value range [0,1], adjust the value of f within the value range [f L , f H , and calculate the corresponding value of P AR,f,m ', so as to obtain the surface.

[0068] Among them, in the constructed oxyz coordinate system, o is the coordinate origin, the x-axis represents frequency, the y-axis represents the matching degree m, and the z-axis represents the acoustic power, P AR,f,m ' represents the acoustic power corresponding to the adjusted model when the operating frequency of the electroacoustic transducer is f and the matching degree is m. The value range of m is [0, 1], and the value range of f is [f L , f H , f L , f H are respectively the minimum operating frequency and the maximum operating frequency of the electroacoustic transducer. That is, when f is a certain frequency value, by making m take values within the range of [0, 1], multiple P AR,f,m ' values can be obtained. Among them, the m value corresponding to the largest P AR,f,m ' value is the m f value corresponding to this frequency value.

[0069] The adjusted model is a model obtained by adjusting the equivalent model of the electroacoustic transducer; the adjustment of the equivalent model of the electroacoustic transducer is specifically: modifying the reactance X of the electrical terminal structure at the reactance value corresponding to the operating frequency f of the electroacoustic transducer f to (1 - m)X f .

[0070] The eddy current equivalent structure is a parallel structure composed of a parallel connection of an eddy current equivalent inductor and an eddy current equivalent resistor, X f = Im(Z ES,f ); among them, Im(Z ES,f ) represents the imaginary part of Z ES,f , and Z ES,f represents the impedance of the eddy current equivalent structure when the operating frequency of the electroacoustic transducer is f, R ES,f , L ES,f correspond to the inductance value of the eddy current equivalent inductor and the resistance value of the eddy current equivalent resistor when the operating frequency of the electroacoustic transducer is f respectively, and j represents the imaginary unit, ω = 2πf.

[0071]

[0072] Among them, Z AM ' = Z AM , Z AF ' = Z AF .

[0073] Z AE ' represents the equivalent impedance after the impedance of the electrical terminal structure of the adjusted model when the operating frequency of the electroacoustic transducer is f and the matching degree is m is converted to the acoustic terminal structure, Z AM ', Z AF' respectively represent the equivalent impedance after the impedance of the mechanical end structure of the adjusted model is reduced to the acoustic end structure, the impedance of the acoustic end structure of the adjusted model, Z AM 、Z AF respectively represent the equivalent impedance after the impedance of the mechanical end structure of the electro-acoustic transducer equivalent model is reduced to the acoustic end structure, the impedance of the acoustic end structure of the electro-acoustic transducer equivalent model, S d represents the equivalent radiation area of the electro-acoustic transducer, Bl represents the electromechanical coupling factor of the electro-acoustic transducer, represents the output voltage of the power amplifier, represents the modulus value of

[0074] When the eddy current equivalent structure is a parallel structure composed of a parallel connection of an eddy current equivalent inductor and an eddy current equivalent resistor, the equivalent impedance Z AE 、the impedance Z AE ' of the electrical end structure of the electro-acoustic transducer equivalent model reduced to the acoustic end structure is calculated according to the following formula:

[0075]

[0076]

[0077] R E represents the resistance value of the static equivalent resistance.

[0078] The mechanical end structure includes a dynamic resistor, a dynamic inductor, and a dynamic capacitor connected in series;

[0079]

[0080] Among them, R AM 、L AM 、C AM respectively correspond to the values of the resistance of the dynamic resistor, the inductance of the dynamic inductor, and the capacitance of the dynamic capacitor after being reduced to the acoustic end, R M 、L M 、C M respectively correspond to the resistance value of the dynamic resistor, the inductance value of the dynamic inductor, and the capacitance value of the dynamic capacitor.

[0081] When the operating frequency of the electro-acoustic transducer is f, the transfer function G PR,f (s) in the s domain is:

[0082]

[0083] Among them, k p,f 、k r,fare the proportional coefficient and the resonant coefficient of the PR controller, respectively, and ω c is the cut-off angular frequency of the PR controller.

[0084] The present invention also provides an electroacoustic transducer bandwidth expansion device, which is characterized by including a processor configured to execute the electroacoustic transducer bandwidth expansion method described above.

[0085] The following details the solution of Embodiment 1.

[0086] In practice, the transducer cannot be simply equivalent, and there is an energy conversion process between "electricity", "mechanics" and "sound". Therefore, in the impedance matching process of this application, first, a refined modeling analysis is carried out on the electroacoustic transducer, the mechanism between its impedance and sound power and bandwidth is studied, and then an optimal bandwidth solution model is established according to the relationship between the impedance parameters and the transducer sound power and bandwidth respectively. The optimal impedance matching value is solved according to the model, so as to realize the optimization of bandwidth and sound power.

[0087] The present invention starts from the essence of the transducer, studies the feasible method for expanding the active matching bandwidth of the transducer, and provides a reasonable and effective solution for the bandwidth expansion of the transducer in practical applications. The present invention combines the active impedance matching theory with the bandwidth expansion principle of the matching layer of the piezoelectric transducer, changes the quality factor by matching the equivalent impedance of the electrical terminal structure of the transducer, and then expands the bandwidth of the transducer. In order to avoid the reduction of the sound power of the transducer while expanding the bandwidth, the present invention establishes a dynamic matching model of the optimal bandwidth on the premise of ensuring the sound power. Finally, through experimental simulation, the effectiveness of the proposed active matching bandwidth expansion method is verified.

[0088] The coefficients in the relational expression of the inductance value of the eddy current equivalent inductance and the working frequency value, the coefficients in the relational expression of the resistance value of the eddy current equivalent resistance and the working frequency value, and the parameter values of each component of the electroacoustic transducer equivalent model are obtained through identification.

[0089] 1. Relationship between bandwidth and sound power

[0090] In order to better study how to improve the transducer bandwidth on the premise of ensuring the sound power, it is first necessary to finely characterize the relationship between the bandwidth and the sound power. Therefore, the present invention conducts a detailed analysis on the basis model of the electroacoustic transducer, establishes a complete equivalent model, and further obtains a calculation method for the sound power based on the equivalent model.

[0091] 1.1 Transducer modeling

[0092] As Figure 1 shown is an equivalent model of an existing electroacoustic transducer, which is coupled by an electrical terminal structure, a mechanical terminal structure, and an acoustic terminal structure.

[0093] The equivalent model of the electro-acoustic transducer consists of three parts of circuits: the electrical terminal structure, the mechanical terminal structure, and the acoustic terminal structure.

[0094] The electrical terminal structure includes a static equivalent resistance (with a resistance value of R E ), an eddy current equivalent resistance (with a resistance value of R ES,f , and the resistance value is related to the operating frequency of the transducer), and an eddy current equivalent inductance (with an inductance value of L ES,f , and the inductance value is related to the operating frequency of the transducer).

[0095] The mechanical terminal structure includes a dynamic inductance (with an inductance value of L M ), a dynamic capacitance (with a capacitance value of C M ), and a dynamic resistance (with a resistance value of R M ).

[0096] The acoustic terminal structure is composed of the acoustic terminal structure impedance. N1 is the coupling coefficient between the electrical terminal structure and the mechanical terminal structure, and N2 is the coupling coefficient between the mechanical terminal structure and the acoustic terminal structure. Their calculation formulas are as follows:

[0097]

[0098] From Figure 4 it can be seen that the high-frequency equivalent model after being reduced to the acoustic terminal structure in the adjusted model consists of a static circuit, a dynamic circuit, and an acoustic terminal structure circuit. Among them, the static circuit includes a static equivalent resistance (with a resistance value of R AE ), a high-frequency eddy current equivalent capacitance (with a capacitance value of C AES ), and a high-frequency eddy current equivalent resistance (with a resistance value of R AES ). The dynamic circuit includes a reduced dynamic resistance (with a resistance value of R AM ), a reduced dynamic inductance (with an inductance value of L AM ), and a reduced dynamic capacitance (with a capacitance value of C AM ). R AE , R AM , L AM , C AM respectively represent the values of the parameters corresponding to the static equivalent resistance, dynamic resistance, dynamic inductance, and dynamic capacitance after being reduced to the acoustic terminal structure. S d represents the equivalent radiation area of the electro-acoustic transducer, and Bl represents the electromechanical coupling factor of the electro-acoustic transducer. R AE represents the value of the static equivalent resistance after being reduced to the acoustic terminal structure, ω = 2πf, and j represents the imaginary unit.

[0099] In Figure 1 's model, the original structure with the eddy current equivalent resistance and eddy current equivalent inductance in parallel can be equivalent to a structure with a resistance and an inductance in series (the impedance value of the resistance is Re(Z ES,f ), and the reactance value of the inductance is Im(ZES,f )),that is, the reactance of the equivalent model of the original electroacoustic transducer at the operating frequency f of the electroacoustic transducer is X f = Im(Z ES,f ). Therefore, in Figure 2 the adjusted model, the reactance X f of the electrical terminal structure in the adjusted model is modified to (1 - m)X f = (1 - m)Im(Z ES,f ).

[0100] The solution formulas for each parameter are shown in Equations (2)-(7):

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107] As Figure 12 shown, for the response curve of the transducer, the width between two frequency points when it is less than 3 dB of the maximum response, that is, the frequency difference between the two, is defined as the bandwidth. That is

[0108] BW = f b - f a (8)

[0109] In the formula, f a , f b respectively represent the frequencies corresponding to when the transducer is at half power (i.e., half of the maximum acoustic power).

[0110] ω s is the resonant angular frequency of the electroacoustic transducer:

[0111]

[0112] The total quality factor of the electroacoustic transducer consists of the electrical quality factor (or electrical quality factor) and the mechanical quality factor:

[0113]

[0114]

[0115]

[0116]

[0117] Among them, Q E is the electrical quality factor, and Q M is the mechanical quality factor.

[0118] 1.2 Sound power calculation model

[0119] The power radiated by the electroacoustic transducer on the forward infinite baffle is regarded as its sound power. Therefore, according to the definition, the sound power calculation formula can be obtained:

[0120]

[0121] In the formula, I D ’ is the sound velocity of the adjusted model, and Z AF ’ is the acoustic impedance of the adjusted model.

[0122] According to the equivalent model, the solution expressions for the sound velocity and acoustic impedance can be obtained as follows: First, calculate the impedance of each part of the entire circuit equivalent model respectively, and then obtain the value of U through Kirchhoff's current law. D Value.

[0123]

[0124]

[0125]

[0126] Among them, Z AE ', Z AM ' are the equivalent impedances of the electrical terminal structure and the mechanical terminal structure of the adjusted model after being reduced to the acoustic terminal structure respectively.

[0127] 2. Transducer active matching network

[0128] Compared with the mechanical impedance which is closely related to the physical structure of the transducer and is difficult to change, the impedance of its electrical terminal structure can be changed by an external circuit. Currently, the main impedance matching methods include static impedance matching and dynamic impedance matching methods, that is, methods such as connecting a fixed-value capacitor or inductor in series at the electrical terminal structure and dynamically switching capacitor banks to offset the influence caused by reactance. A large number of transducer impedance matching studies are all based on this to maximize the output efficiency of the transducer. However, for electroacoustic transducers, in addition to maximizing the output efficiency, it is more important to expand its working bandwidth. Since the eddy current equivalent inductance of the electrical terminal structure is frequency-dependent and its magnitude changes with frequency, both of the above methods cannot achieve real-time dynamic adjustment of the matching amount. Therefore, Embodiment 1 of the present invention proposes an active matching network based on an inverter, as Figure 4 shown.

[0129] Figure 4 The active matching circuit shown includes an AC-side filtering capacitor C s and a filtering inductor L s , a DC-side capacitor C dc and a DC-side power supply V dc and a single-phase full-bridge inverter. V is the output voltage of the power amplifier. One output terminal of it is directly electrically connected to one driving terminal of the electroacoustic transducer, and the other output terminal is electrically connected to one end of the filtering capacitor. The other end of the filtering capacitor is connected to the other driving terminal of the electroacoustic transducer. The two output terminals of the DC-side power supply of the inverter are respectively connected to the corresponding input terminals of the single-phase full-bridge inverter, and the DC-side capacitor is connected in parallel with the DC-side power supply. The two output terminals A and B of the single-phase full-bridge inverter are respectively based on one end of the filtering inductor and the other end of the filtering capacitor, and the other end of the filtering inductor is connected to one end of the filtering capacitor.

[0130] 3. Bandwidth expansion method

[0131] In order to expand the bandwidth of the electroacoustic transducer by using the proposed active matching method, since the electrical terminal structural impedance is frequency-dependent, it is first necessary to calculate the impedance matching magnitudes at different frequencies so that the acoustic power corresponding to each operating frequency is maximized, thereby stretching the response curve on the frequency axis and significantly increasing the bandwidth. In addition, to achieve real-time impedance matching, a control system with fast and accurate response capabilities needs to be designed. For this purpose, the present invention first proposes an optimal impedance matching method to balance the relationship between the transducer and the bandwidth and achieve optimal matching.

[0132] 3.1 Optimal impedance matching method

[0133] The present invention aims to maximize the acoustic power at each operating frequency point, so that the acoustic power corresponding to the same frequency point is higher than the original corresponding frequency point. Since the maximum acoustic power remains unchanged, the bandwidth of the electroacoustic transducer is broadened.

[0134] 3.2 PR closed-loop controller design

[0135] First, the transfer function of the PR controller is given as

[0136]

[0137] where k p is the proportionality coefficient; k r is the resonance coefficient, and ω0 is the resonance angular frequency. At the resonance frequency ω0, the gain of the PR controller is infinite, so that static-error-free tracking of a sinusoidal signal with the resonance frequency can be achieved.

[0138] However, the above formula is an ideal PR controller. It contains the internal model of the sinusoidal given signal and can achieve static error-free tracking of the output signal. However, the bandwidth of the ideal PR controller is very small and it only works for sinusoidal signals of a single frequency. Some studies have pointed out that in practical applications, due to the limitations of analog devices and the accuracy of digital controllers, it is very difficult to obtain the accurate resonance frequency, which severely limits the effect of the ideal PR controller in suppressing the steady-state error of the inverter output. Therefore, the ideal PR controller has been improved by adding a damping term on the basis of the ideal PR controller, and its transfer function is shown in the following formula:

[0139]

[0140] In order to enable the controller to effectively control the transducer at different operating frequencies, the resonance frequency ω 0,i in the present invention will i dynamically change with the operating frequency f 0,i and ω

[0141] =2πf. A variable-parameter PR closed-loop method that changes according to the operating frequency can be adopted, so that the active matching network can match the transducer accurately in real time. The present invention realizes the accurate output of the target response through a full-bridge inverter, and realizes the fast and error-free output of the required matching impedance value.

[0142] Those skilled in the art can obtain the proportional coefficient and resonance coefficient of the PR control corresponding to each frequency according to experience. That is, the proportional coefficient and resonance coefficient corresponding to each frequency are preset in advance. When the operating frequency of the transducer changes, not only the value of the corresponding matching degree m f is adjusted, but also the coefficients of the PR controller can be adjusted to the coefficient values corresponding to the changed operating frequency. Those skilled in the art can understand that when the change in the operating frequency is small, the coefficients of the PR controller can also remain unchanged. That is, a set of coefficients (proportional coefficient, resonance coefficient) of the PR controller can be made to correspond to a certain frequency range. When the operating frequency changes from one frequency range to another frequency range, the coefficients of the PR controller are adjusted again. The values of k p,f and k r,f and ω c can also be obtained by making the values of each parameter satisfy the first condition. The first condition is: the steady-state error σ is not greater than the preset error threshold; where: is the output current reference value, is the measured value of the output current of the power amplifier, and L s is the inductance value of the first inductor.

[0143] Figure 6The block diagram of the active matching network proposed by the present invention is shown. After obtaining the reference voltage signal, the matching network obtains the control voltage through the inverter link. After the control voltage passes through the filter inductor, a matching voltage signal V m (s) is generated across the filter capacitor. This signal acts on the filter capacitor to generate a matching current I ac_ref (s). The matching current and the filter inductor current together constitute the load current I ac (s). The active matching network and the adaptive PR controller proposed by the present invention together constitute a closed-loop control system, thereby realizing the expansion of the bandwidth of the electroacoustic transducer.

[0144] Figure 6 The reference current signal I ac_ref (s) is obtained by the optimal impedance matching method proposed in this paper to obtain the optimal matching reactance at the operating frequency (i.e., m f ×Im(Z ES,f )) and then obtained by operating with the matching voltage of the active matching network.

[0145] In Embodiment 1,

[0146] The reference current signal is compared with the operating current I ac (s) of the electroacoustic transducer to obtain an error current signal, which is used as the input of the PR controller to obtain an error control voltage V ac_ref (s). In order to improve the response speed of the closed-loop control system, the reference current signal is fed forward through a proportional controller to obtain a feedforward signal V ac_f (s). The feedforward signal and the error control signal act together to obtain the reference signal V ref (s) of the active matching network.

[0147] 3.3 Transducer Bandwidth Expansion Method

[0148] According to the optimal impedance calculation method and PR control system proposed by the present invention, a transducer bandwidth expansion method is proposed, as shown in Figure 11As shown below. First, the equivalent model of the transducer is established using the relevant parameters of the actual transducer, and its circuit is simplified to obtain the equivalent model of the electro-acoustic transducer reduced to the acoustic end structure. Secondly, a model of bandwidth and acoustic power is established based on the equivalent model of the acoustic end structure, and the maximum acoustic power is calculated. Then, according to the value of the matching degree m corresponding to the point with the maximum acoustic power at each frequency, an optimal impedance matching model is established, and then the optimal impedance matching curve is solved to obtain the impedance matching magnitude corresponding to each operating frequency point of the transducer at the maximum bandwidth. When the operating frequency of the electro-acoustic transducer is set, the control system will determine the matching impedance magnitude according to the operating frequency, and compare it with the actual output signal of the electro-acoustic transducer to obtain its error signal. Finally, combined with the adaptive PR closed-loop control system proposed in the present invention, a control signal is generated using the error signal, and then the active matching network generates a corresponding matching signal according to the control signal until the end.

[0149] 4. Example Analysis

[0150] To verify the rationality and effectiveness of the electro-acoustic transducer bandwidth matching method proposed in the present invention, a simulation experiment was carried out in combination with an actual transducer. In the present invention, a loudspeaker is taken as an example, as Figure 5 shown is the equivalent model of the corresponding acoustic end structure when the loudspeaker is used as an electro-acoustic transducer. The acoustic end structure circuit includes the acoustic end structure inductor L A , the acoustic end structure resistor R A1 , the acoustic end structure resistor R A2 and the acoustic end structure capacitor C A .

[0151] 4.1 Active Matching Parameter Calculation

[0152] The relevant parameters of the electro-acoustic transducer are shown in Table 1.

[0153] Table 1 Transducer Related Parameters

[0154]

[0155] According to the basic parameters of the transducer, the values of each parameter in the equivalent model of the transducer can be obtained from the following formula. The eddy current equivalent model of the loudspeaker is as follows:

[0156]

[0157]

[0158] Among them, L E is the static inductance, and n is the eddy current related coefficient.

[0159] Figure 5 In, each parameter can be calculated using the following formula:

[0160]

[0161]

[0162]

[0163]

[0164] Among them, a is the radiation radius of the acoustic end of the transducer, c is the speed of sound, and ρ is the density of the medium.

[0165] Figure 13 It is the relationship between the acoustic power and frequency of the electro-acoustic transducer before matching obtained after establishing the equivalent circuit model of the acoustic end structure by using the above parameters of the electro-acoustic transducer. It can be known that the bandwidth of the electro-acoustic transducer is the working frequency difference at the half-power point, which is 170 Hz, and P max is 0.213 W.

[0166] Furthermore, an optimal matching model is established, and Matlab is used for optimization and solution. The relationships between the acoustic power and bandwidth under different matching degrees are as Figure 14 shown. From Figure 14 it can be seen that as the matching degree increases, the bandwidth of the electro-acoustic transducer is continuously improved. At the same time, its maximum acoustic power gradually decreases. This indicates that due to the frequency correlation of the eddy current equivalent inductance of the electrical end structure of the electro-acoustic transducer, in order to ensure the acoustic power of the electro-acoustic transducer during the matching process, it is necessary to change the matching degree at different working frequencies. Through optimization and solution, the optimal matching curve can be obtained in the surface as Figure 14 shown by the red curve in.

[0167] According to Figure 14 the red optimal curve in, the optimal impedance matching curve of Figure 15 is obtained. From Figure 15 it can be seen that by using the optimal matching method proposed in the present invention, the bandwidth of the electro-acoustic transducer at the half-power point is 443 Hz, which is 273 Hz wider than that before matching and 2.6 times that before matching, indicating the effectiveness of the method proposed in the present invention.

[0168] 4.2 Active Matching Network Simulation Experiment

[0169] To further verify the control performance of the proposed method, an electro-acoustic transducer bandwidth expansion model proposed in the present invention is built in Simulink to analyze the effectiveness of the system at different working frequencies. Figure 16-1 、 Figure 16-2 、 Figure 16-3The results of the simulation experiment include the response of the matching network output voltage when switching at different frequency points, as well as the comparison between the calculated value of the matching reactance and the actual response value. It can be seen that the matching network smoothly transitions from the initial moment to near the target value and then stabilizes at the target value after a small oscillation. When the operating frequency changes, the matching network can quickly respond and reach stability again in only one and a half cycles. In addition, by analyzing the actual curve and the calculated curve of the matching reactance, it can be known that the error between the calculated reactance and the actual matching reactance passing through the matching network is very small during the adjustment process, indicating that the proposed matching network has good control performance and can achieve real-time and accurate impedance matching.

[0170] As an important parameter index of electroacoustic transducers, broadening the bandwidth of electroacoustic transducers enables them to carry more information and have better detection capabilities. Therefore, the research on improving the working bandwidth of electroacoustic transducers is extremely important.

[0171] Based on the basic theory of transducers, the present invention first comprehensively analyzes the structure of the transducer and establishes a complete equivalent model; then analyzes the decisive factors affecting the acoustic power and bandwidth of the electroacoustic transducer according to the equivalent model; secondly, studies the bandwidth expansion mechanism of the electroacoustic transducer obtained from the analysis, constructs an optimization model to maximize the bandwidth of the electroacoustic transducer while ensuring the acoustic power; builds an impedance matching circuit through an active inverter circuit, combines the matching scheme obtained from the optimization model, and effectively expands the bandwidth of the electroacoustic transducer; finally, verifies the effectiveness of the proposed bandwidth expansion method through simulation experiments.

[0172] Embodiment 2

[0173] As shown in Figure 7 is the equivalent model of another electroacoustic transducer in the prior art targeted by Embodiment 2 of the present invention. Figure 7 The difference between the model shown and Figure 1 the model shown is that the eddy current equivalent structure is a series structure composed of an eddy current equivalent inductor and an eddy current equivalent resistor.

[0174] In this Embodiment 2, the eddy current equivalent structure is a series structure formed by the series connection of an eddy current equivalent inductor and an eddy current equivalent resistor, X f = ωL ES,f . The equivalent impedance Z AE of the electrical terminal structure of the electroacoustic transducer equivalent model after being reduced to the acoustic terminal structure, and the equivalent impedance of the impedance Z AE ' of the electrical terminal structure of the adjusted model after being reduced to the acoustic terminal structure are calculated according to the following formula:

[0175]

[0176]

[0177] In Example 2,

[0178] Figure 8 It is for Figure 7 Schematic diagram of the adjusted model obtained from the model. Figure 9 Yes Figure 8 The model obtained by converting the electrical end structure and mechanical end structure of the adjusted model to the acoustic end structure. Figure 10 The active impedance matching circuit in Embodiment 2 of the present invention and Figure 7 The control block diagram in this embodiment 2 is the same as that in embodiment 1, and is also Figure 6 The method steps of this embodiment 2 also adopt Figure 11 The method steps are shown.

[0179] The calculation is done using the following formula:

[0180]

[0181]

[0182] R AE , R AM , L AM , C AM The calculation formula is the same as that in Example 1.

[0183] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0184] The embodiments of the present invention are described in detail above, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent. After reading the present invention, modifications of various equivalent forms of the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

Claims

1. A method for expanding the bandwidth of an electroacoustic transducer with an active impedance matching circuit, wherein the active impedance matching circuit includes a single-phase full-bridge inverter (30) connected to the driving end of the electroacoustic transducer (10); two switching tubes of one arm of the single-phase full-bridge inverter (30) have a first common connection end (A), and two switching tubes of the other arm have a second common connection end (B); two input ends of the single-phase full-bridge inverter (30) are respectively and electrically connected to two output ends of a DC power supply module (4); the first common connection end (A) is electrically connected to the first end of a first inductor (2), and the second common connection end (B), the first end of a first capacitor (1), and one driving end of the electroacoustic transducer (10) are electrically connected to each other; the second end of the first inductor (2), the second end of the first capacitor (1), and one output end of a power amplifier are electrically connected to a first electrical connection point (P1), and the other output end of the power amplifier and the other driving end of the electroacoustic transducer (10) are electrically connected to each other; The equivalent model of the electroacoustic transducer is formed by coupling an electrical terminal structure, a mechanical terminal structure, and an acoustic terminal structure in sequence; the electrical terminal structure includes a static equivalent resistance and an eddy current equivalent structure connected in series between two input ends of the electroacoustic transducer; It is characterized in that: The method for expanding the bandwidth of the electroacoustic transducer includes: When the operating frequency of the electroacoustic transducer is f, let the reference value of the output current The expression of I ac_ref (s) in the s-domain is where s represents the variable of the s-domain function; V m (s) is the difference between the voltage at the second end of the first capacitor (1) and the voltage at the first end of the first capacitor (1) measured The expression in the s-domain, X f (s) is the expression of X f The expression of X f is the imaginary part of the impedance of the eddy current equivalent structure when the operating frequency of the electroacoustic transducer is f; Make I ac_ref (s) pass through a proportional controller to obtain a feedforward voltage reference value V ac_f (s); I ac_ref (s) subtracts I ac (s) to obtain a current error signal ΔI ac , the current error signal ΔI ac after passing through a PR controller is added to the feedforward voltage reference value V ac_f (s), and the result of the addition is subjected to PWM modulation to obtain a duty cycle signal for the switching tubes of the single-phase full-bridge inverter (30); Among them, I ac (s) is the measured value of the output current of the power amplifier Expression in the s domain; m f is the matching degree corresponding to the point with the maximum sound power among the points of the surface corresponding to the frequency f; The surface is the surface of the relationship between P AR,f,m ' in the oxyz coordinate system and the operating frequency and matching degree m of the electroacoustic transducer; In the constructed oxyz coordinate system, o is the coordinate origin, the x-axis represents frequency, the y-axis represents the matching degree m, and the z-axis represents the acoustic power, P AR,f,m ' represents the acoustic power corresponding to the adjusted model when the operating frequency of the electroacoustic transducer is f and the matching degree is m. The value range of m is [0, 1], and the value range of f is [f L , f H , f L , f H are respectively the minimum operating frequency and the maximum operating frequency of the electroacoustic transducer; The adjusted model is a model obtained by adjusting the equivalent model of the electroacoustic transducer; the adjustment of the equivalent model of the electroacoustic transducer is specifically: changing the reactance value X of the electrical terminal structure at the operating frequency f of the electroacoustic transducer f to (1 - m)X f .

2. The method for expanding the bandwidth of the electroacoustic transducer according to claim 1, wherein: The eddy current equivalent structure is a series structure composed of a series connection of an eddy current equivalent inductor and an eddy current equivalent resistor, X f = ωL ES,f ; or The eddy current equivalent structure is a parallel structure composed of a parallel connection of an eddy current equivalent inductor and an eddy current equivalent resistor, X f = Im(Z ES,f ); where Im(Z ES,f ) represents the imaginary part of Z ES,f , and Z ES,f represents the impedance of the eddy current equivalent structure when the operating frequency of the electroacoustic transducer is f. R ES,f and L ES,f respectively correspond to the inductance value of the eddy current equivalent inductance and the resistance value of the eddy current equivalent resistance when the operating frequency of the electroacoustic transducer is f. j represents the imaginary unit, and ω = 2πf.

3. The method for expanding the bandwidth of the electroacoustic transducer according to claim 1, characterized in that: Among them, Z AM ' = Z AM ,Z AF ' = Z AF ; Among them, Z AE ' represents the equivalent impedance after the impedance of the electrical terminal structure of the adjusted model when the operating frequency of the electro-acoustic transducer is f and the matching degree is m is reduced to the acoustic terminal structure. Re(Z AF ) represents the real part of Z AF '. Z AM ', Z AF ' respectively represent the equivalent impedance after the impedance of the mechanical terminal structure of the adjusted model is reduced to the acoustic terminal structure and the impedance of the acoustic terminal structure of the adjusted model. Z AM , Z AF respectively represent the equivalent impedance after the impedance of the mechanical terminal structure of the equivalent model of the electro-acoustic transducer is reduced to the acoustic terminal structure and the impedance of the acoustic terminal structure of the equivalent model of the electro-acoustic transducer. S d represents the equivalent radiation area of the electro-acoustic transducer, Bl represents the electromechanical coupling factor of the electro-acoustic transducer, represents the output voltage of the power amplifier, represents 's modulus value.

4. The method for expanding the bandwidth of the electroacoustic transducer according to claim 3, characterized in that: When the eddy current equivalent structure is a series structure composed of a series connection of an eddy current equivalent inductor and an eddy current equivalent resistance: or When the eddy current equivalent structure is a parallel structure composed of a parallel connection of an eddy current equivalent inductor and an eddy current equivalent resistance: R E represents the resistance value of the static equivalent resistance, Re(Z ES,f ) represents the real part of Z ES,f .

5. The method for expanding the bandwidth of an electroacoustic transducer according to claim 1, wherein: The mechanical terminal structure includes a dynamic resistance, a dynamic inductor, and a dynamic capacitor connected in series; Among them, R AM 、L AM 、C AM respectively correspond to the values of the resistance of the dynamic resistance, the inductance of the dynamic inductance, and the capacitance of the dynamic capacitance after being converted to the acoustic end. R M 、L M 、C M respectively correspond to the resistance value of the dynamic resistance, the inductance value of the dynamic inductance, and the capacitance value of the dynamic capacitance.

6. The method for expanding the bandwidth of an electroacoustic transducer according to any one of claims 1-5, characterized in that: When the operating frequency of the electroacoustic transducer is f, the transfer function G PR,f (s) in the s-domain is as follows: Among them, k p,f , k r,f are the proportional coefficient and the resonance coefficient of the PR controller respectively, and ω c is the cut-off angular frequency of the PR controller.

7. The method for expanding the bandwidth of the electroacoustic transducer according to any one of claims 1-5, characterized in that Adjust the value of m within the range [0, 1], adjust the value of f within the range [f L , f H , and calculate the corresponding value of P AR,f,m ', so as to obtain the said surface.

8. An electroacoustic transducer bandwidth expansion device, characterized in that Including a processor configured to execute the method for expanding the bandwidth of the electroacoustic transducer according to any one of claims 1-7.

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