Hybrid impedance matching topology and control method thereof

Abstract

The present invention discloses a hybrid impedance matching topology structure and a control method thereof, wherein the hybrid impedance matching topology structure comprises: an active converter, the input side of which is connected to a power amplifier; a capacitor module, which is connected to the output side of the active converter; wherein the capacitor module is connected to an electroacoustic transducer, and at the minimum operating frequency, the capacitive reactance of the capacitor module is equal to the inductive reactance of the electroacoustic transducer. The present invention can achieve high-precision, wide-band, and wide-load range impedance matching under different loads, power amplifier variable voltage frequencies, and amplitudes.

Description

Technical Field

[0001] The present invention relates to the field of current conversion technology in electrical engineering, and in particular to a hybrid impedance matching topology structure and a control method thereof. Background Art

[0002] Compared with linear power amplifiers, switching power amplifiers (hereinafter referred to as power amplifiers) have the characteristics of high power and low loss, and are widely used in RF, audio, underwater acoustics and other fields. Underwater electroacoustic transducer systems are indispensable in the fields of active underwater detection, remote communications, terrain detection, etc. The power amplifier provides driving voltage for the electroacoustic transducer, but the load power factor of the electroacoustic transducer is low, which limits the output of the power amplifier. How to improve the power provided by the power amplifier to the electroacoustic transducer is of great significance to the electroacoustic transducer system.

[0003] The main factor that limits the output power of the power amplifier is the mismatch between the impedance of the electroacoustic transducer and the impedance of the power amplifier. If the impedance does not match, the output of the power amplifier is limited, and the power received by the electroacoustic transducer is limited, which affects the sound source level of its output, thereby affecting the normal operation of the system. The giant magnetostrictive electroacoustic transducer is usually resistive and inductive in the operating frequency range, so when the power amplifier directly powers the transducer, the system power factor will be very low. Traditional impedance matching uses a series capacitor group for matching. This method has the disadvantages of large size, low adjustment accuracy, and difficulty in adaptive adjustment. Therefore, studying a wide-band automatic impedance matching circuit is of great practical significance for underwater electroacoustic transducer systems.

[0004] "Impedance matching system and matching method for marine communication electroacoustic transducer" (publication number: CN108882108A, publication date: November 23, 2018), which can achieve impedance matching when the working environment of the transducer changes and the load changes. However, it requires a switched capacitor array, which has the disadvantages of large size and low adjustable accuracy. "Impedance matching method and impedance matching system" (publication number: CN105594122B, publication date: March 8, 2019) achieves impedance matching by changing the driving frequency. However, it does not consider the impact of load reactive power on system efficiency. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a hybrid impedance matching topology structure and a control method thereof in view of the deficiencies in the prior art, so as to solve the problem of low power factor caused by impedance mismatch between the power amplifier and the electroacoustic transducer and improve the power output capacity of the power amplifier.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a hybrid impedance matching topology structure, comprising:

[0007] An active converter, the input side of which is connected to a power amplifier;

[0008] A capacitor module connected to the output side of the active converter;

[0009] The capacitor module is connected to the electroacoustic transducer, and when the operating frequency of the hydroacoustic transducer is minimum, the capacitive reactance of the capacitor module is equal to the inductive reactance of the electroacoustic transducer.

[0010] The impedance matching of the present invention is composed of two parts, the series-parallel capacitor group (i.e., capacitor module) can realize rough matching, and the active converter can realize fine matching. The rough matching equivalent capacitance value is determined by the inductive reactance of the transducer at the lowest operating frequency, that is, the inductive reactance of the transducer is equal to the capacitive reactance of the series-parallel capacitor group at the minimum operating frequency. To a certain extent, the problem of low power factor caused by impedance mismatch between the power amplifier and the electroacoustic transducer is solved, and the power output capacity of the power amplifier is improved.

[0011] In order to facilitate the adjustment of the capacitance value of the capacitor module, the capacitor module includes a plurality of parallel branches, and each branch includes a plurality of capacitors connected in series.

[0012] The active converter is a single-module active converter or a multi-module active converter; the single-module active converter includes a full-bridge inverter and a filter circuit, and the midpoints of the two bridge arms of the full-bridge inverter are connected to the filter circuit; the multi-module active converter includes multiple cascaded single-module active converters, and the multi-module active converter can improve the matching range.

[0013] In order to achieve wide-band, dynamic self-adjusting impedance matching and further improve the power output capacity of the power amplifier, the active converter is used to perform precise impedance matching. The specific implementation process includes: collecting the voltage and current of the series circuit of the capacitor module and the electroacoustic transducer, calculating the reactive power that needs to be compensated, and controlling the active converter to generate a corresponding matching voltage to achieve impedance matching.

[0014] The present invention also provides a control method for the above hybrid impedance matching topology structure, comprising:

[0015] 1) For the combined voltage v L , power amplifier output current i L Perform a delay of 1 / 4T and get v L D and L D , calculate the instantaneous power of the combined circuit of the capacitor module and the electroacoustic transducer in series after rough matching:

[0016]

[0017] Among them, p L is the instantaneous active power, q L is the instantaneous reactive power; T is the period of the power amplifier output voltage;

[0018] 2) For p L ,q L Perform low-pass filtering to obtain Use the following formula to calculate the active power P L and reactive power Q L :

[0019] 3) The output voltage of the power amplifier v Co Perform a delay of 3 / 4T to get v Co D , use the following formula to calculate the reference voltage v AB *:

[0020] 4) Set the reference voltage v AB *The control signal that drives the active converter power device is generated through feedforward control and feedback control. Reference voltage v AB * and feedforward control coefficient K f The product of the reference voltage v AB *With actual voltage v AB The difference multiplied by G _PR (s), the sum of the above two is modulated by SPWM to generate a driving signal; the feedback control is a segmented resonant control, and the transfer function is G _PR (s), according to ω 0 The size of G is determined by _PR (s) In which range does it work? Use the following formula to calculate G _PR (s):

[0021]

[0022] Among them, ω 0 is the output voltage v Co Angular frequency; K P1 , K P2 , …, K Pn is the proportional coefficient of segmented resonance control; K I1 , K I2 , …, K In is the integral coefficient of segmented resonance control; ω c is the angular frequency bandwidth of segmented resonance control; ω 2 ,ω 3 ,…,ω n S is the segmented frequency point of segmented resonance control; S 1 , S 2, …, S n is the symbol of the working range of the segmented resonance control; v AB * is the reference voltage output by the active converter; v AB is the actual voltage generated by the active converter.

[0023] The DC voltage V of the active converter dc The product of the modulation factor m is greater than the reference voltage v AB *, m is generally around 0.9; when the output voltage frequency and amplitude of the power amplifier are at their maximum, the reactive power generated by the underwater acoustic transducer is at its maximum, and the voltage v that needs to be matched is AB * Also the maximum value.

[0024] Before the above step 1), it also includes: using a zero-crossing comparison method to calculate the power amplifier output voltage v in real time Co The phase angle ω 0 and period T.

[0025] The present invention adopts active converter and capacitor module to carry out impedance matching. The capacitor module matches part of reactive power, and the remaining reactive power is matched through active converter. The combination of the two broadens the matching frequency band. The matching of the capacitor module is not adjustable, and is used to match the reactive power of the electroacoustic transducer working at the lowest frequency. According to the increase of the working frequency and amplitude of the transducer, the capacitor module is not enough to compensate the reactive power of the electroacoustic transducer. At this time, the matching is carried out through the active converter. The active converter can match in real time according to the change of the working frequency of the underwater acoustic transducer, thereby realizing wide-band, dynamic self-adjusting impedance matching and improving the power output capacity of the power amplifier.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1) The present invention matches the load of the electroacoustic transducer, and through a matching method combining an active converter with a capacitor module, the circuit in which the impedance matching circuit is connected in series with the electroacoustic transducer becomes purely resistive as a whole, so that the power amplifier only outputs active power, thereby improving the output capacity of the power amplifier;

[0028] 2) Compared with the existing impedance matching devices, the present invention can achieve wideband through mixed matching of capacitor mode and active converter under different load, power amplifier voltage frequency and amplitude conditions, and the active converter can achieve high-precision impedance matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 1. It is a schematic diagram of a hybrid impedance matching topology structure and its arrangement position according to an embodiment of the present invention;

[0030] Figure 2 is a control block diagram of an embodiment of the present invention;

[0031] Figure 3 It is a comparison diagram of transient voltage and current on the electroacoustic transducer side, the power amplifier side, and the hybrid impedance matching topology structure side before and after changing the output voltage frequency of the power amplifier using the present invention for load matching in a simulation example, and a curve diagram of the power amplifier output power and the electroacoustic transducer load power;

[0032] Figure 4 It is a transient voltage and current comparison diagram of the electroacoustic transducer side, the power amplifier side, and the hybrid impedance matching topology structure side before and after changing the output voltage value of the power amplifier when load matching is performed using the present invention in a simulation example, as well as a curve diagram of the power amplifier output power and the electroacoustic transducer load power. DETAILED DESCRIPTION

[0033] The present invention utilizes a group of series-parallel capacitors and an active converter in series to form a hybrid impedance matching topology structure, the front end of which is connected to a power amplifier, and the rear end is connected to an electroacoustic transducer to match the reactive power of the electroacoustic transducer. The series-parallel capacitor group is composed of a plurality of capacitors in series and in parallel, and the active converter can be a single-module active converter or a multi-module active converter. The single-module active converter is composed of a full-bridge inverter and a filter circuit, and the multi-module active converter is composed of a single-module active converter cascaded. The impedance characteristics of the electroacoustic transducer in a certain working frequency band can be measured by an impedance measuring instrument. The impedance matching of the present invention consists of two parts, the series-parallel capacitor group realizes coarse matching, and the active converter realizes fine matching. Coarse matching is matching with capacitors, which is a primary matching and cannot be adjusted. Fine matching is matching with active converters, which is a secondary matching and can be adjusted. The coarse matching equivalent capacitance value is determined by the inductive reactance of the transducer at the lowest working frequency, that is, the inductive reactance of the transducer is equal to the capacitive reactance of the series-parallel capacitor group at the minimum working frequency. Precise matching calculates the reactive power that needs to be compensated by collecting the voltage and current of the series-parallel capacitor group and the series circuit of the electroacoustic transducer, and realizes impedance matching by controlling the active converter to generate the corresponding matching voltage.

[0034] like Figure 1 As shown, the embodiment of the present invention includes an active converter and a series-parallel capacitor group (ie, capacitor module), the active converter and the series-parallel capacitor group are connected in series, and the above circuit constitutes a hybrid impedance matching topology structure.

[0035] The front end of the hybrid impedance matching topology is connected to the positive pole of the power amplifier, and the back end is connected to the electroacoustic transducer, which is connected in series in the loop formed by the power amplifier and the electroacoustic transducer. The power amplifier can generate a voltage with variable amplitude and frequency, and the output voltage is v Co , the loop current is i L ; The electroacoustic transducer is a load, which can be equivalent to a resistive-inductive load, that is, R eq +Leq , the voltage across the two ends is v o The hybrid impedance matching topology is used to achieve impedance matching between the power amplifier and the electroacoustic transducer. The active converter is responsible for precise matching, and the voltage across it is expressed as v AB The series-parallel capacitor group is responsible for rough matching, and the voltage across the two ends is v c .v AB Add v c Get the combined voltage v L , that is, the combined voltage v after the electroacoustic transducer is roughly matched by the series-parallel capacitor group L .

[0036] like Figure 1 As shown, the active converter can be a single-module active converter or a multi-module active converter. In the single-module active converter, the DC capacitor C dc Provides DC voltage V dc , fully controlled power electronic devices (IGBT or MOSFET) T aM , T bM , A full-bridge inverter is formed, and an LC filter is connected to the output side of the full-bridge inverter. f is the filter inductor, C f is the filter capacitor, filter capacitor C f The output terminals A and B are consistent with the interfaces of the active converter. dc Together with the active full-bridge inverter, it forms a single-module active converter.

[0037] The multi-module active converter is composed of n single-module active converters connected in series and then connected in parallel with an LC filter; the LC filter is composed of a filter inductor L f2 And filter capacitor C f2 Composition. Filter capacitor C f2 It is the output end, and the output interfaces A and B are consistent with the interfaces of the active converter.

[0038] The series-parallel capacitor group includes multiple parallel capacitor branches, each capacitor branch includes multiple series capacitors, and the equivalent capacitance value of the series-parallel capacitor group is C M The coarse matching is to match part of the reactive power of the electroacoustic transducer with the series-parallel capacitor group. M It can be calculated from the following relationship: when the system has the minimum operating frequency f, the capacitive reactance of the series-parallel capacitor group is equal to the inductive reactance of the electroacoustic transducer.

[0039] The present invention uses the zero-crossing comparison method to obtain the power amplifier output voltage v in real time. Co The phase angle ω 0And period T. Then according to the combined voltage v of the series-parallel capacitor group and the electroacoustic transducer series circuit L , loop current i L Then, based on the goal that the active power is provided by the power amplifier and the reactive power is provided by the active converter, the active converter output reference voltage v is calculated. AB *. Then according to ω 0 The working range is determined by the value of v. Each range corresponds to a PR controller. Multiple segmented PR controllers are applied to realize the reference signal v AB * Tracking without static error. The final impedance matching active converter part generates a corresponding matching voltage, and the matching voltage of the series-parallel capacitor group is added to achieve impedance matching between the power amplifier and the transducer load.

[0040] like Figure 2 , the control method of the embodiment of the present invention comprises the following steps:

[0041] 1)v Co The detection of period T is realized by the zero-crossing comparison method;

[0042] 2) The combined voltage v L , loop current i L Make a delay of 1 / 4T to get v L D and L D , and the calculation of formula (1) can be used to calculate the instantaneous power of the combined circuit of the series-parallel capacitor group and the electroacoustic transducer in series after rough matching, where p L is the instantaneous active power, q L is the instantaneous reactive power; then for p L ,q L Low-pass filtering is performed to obtain right Calculate the formula (2) to get the active power P L ,right Calculate the reactive power Q by using formula (2) L ;

[0043]

[0044]

[0045]

[0046] 3) The power amplifier output voltage v Co Make a delay of 3 / 4T to get v Co D ; Then do the calculation of formula (4) to calculate the reference voltage v of the active converterAB *;

[0047]

[0048] 4) Reference voltage v AB *Then a feedforward + feedback control generates a control signal for driving the power device; where G _PR (s) is the transfer function of the segmented resonant controller in the s domain, as shown in equation (5), where ω 0 =2π / T, that is, the system's operating frequency band is divided into multiple segments, and the control parameters of each segment are designed separately; K f is the feedforward coefficient, which is generally less than 0.1.

[0049]

[0050] In the embodiment of the present invention, the method for determining the parameters of each component is as follows:

[0051] Equivalent capacitance C of series-parallel capacitor group M Determined by the equivalent inductance of the electroacoustic transducer when it works at the lowest frequency, it satisfies (ω 0 ) min L eq =1 / ((ω 0 ) min C M ).

[0052] The DC voltage V of the active converter dc The product of the modulation factor must be greater than the reference voltage v AB *Amplitude, when the power amplifier output voltage frequency and amplitude are maximum v AB *Get the maximum value.

[0053] Figure 3 , 4 Some working conditions in the simulation example of the present invention are as follows:

[0054] This simulation example is used to verify the effectiveness of the hybrid impedance matching topology structure and control method for high-power electroacoustic transducer system proposed by the present invention, which can effectively achieve impedance matching of the system when the power amplifier output voltage has different frequencies and amplitudes. Therefore, two different dynamic working processes are shown in the simulation, namely: 1) The initial output voltage of the power amplifier is 220V, 200Hz, and the frequency is switched after 20ms. The frequency is increased to 500Hz, and the output voltage value remains unchanged, see Figure 3 ; 2) The initial output voltage of the power amplifier is 220V, 300Hz. After 20ms, the voltage value is switched and the voltage is increased to 380V. The output frequency remains unchanged. See Figure 4 .

[0055] Power amplifier system parameters:

[0056] Output voltage range: V Co =220V~380V, output frequency range: f=200Hz~500Hz.

[0057] Load part parameters:

[0058] Equivalent inductance of electroacoustic transducer: L eq =20mH, equivalent resistance value of electroacoustic transducer: R eq =24Ω.

[0059] Hybrid impedance matching topology parameters:

[0060] Active converter: V dc =800V; Series-parallel capacitor group: C M =31.7μF.

[0061] The following situations are all simulation results using the present invention.

[0062] See also Figure 3 In the interval of 0ms to 20ms, the power amplifier outputs an effective value of 220V voltage and a frequency of 200Hz to the electroacoustic transducer load. However, due to the presence of a large number of equivalent inductive loads on the electroacoustic transducer load side, the current at the electroacoustic transducer end lags behind the voltage, and the power factor is 0.69, which greatly reduces the power output capacity of the power amplifier. However, on the power amplifier side of the hybrid impedance matching topology, the output voltage and current of the power amplifier are matched to the same phase, and the power factor is increased to 1, which improves the output capacity of the power amplifier. In the above interval, the series-parallel capacitor group is mainly used for coarse matching. The equivalent capacitive reactance of the series-parallel capacitor group is equal to the value of the equivalent inductive reactance of the electroacoustic transducer. Therefore, the active converter plays a role of fine matching at low frequencies. The output frequency of the power amplifier is increased to 500Hz at 20ms and lasts until 40ms. During this period, the power factor on the electroacoustic transducer load side is reduced to 0.36. The hybrid impedance matching topology can also make the current and voltage on the power amplifier side in phase and have a power factor of 1 after a short transient process (5ms). In addition, in the high-frequency stage, the series-parallel capacitor group and the active converter are matched at the same time, the matching ability of the series-parallel capacitor group is fixed, and the matching ability of the active converter is adjustable. This simulation example proves that the impedance matching topology of the present invention can operate in a wider frequency range and has the function of automatic adjustment. The results of this simulation example are summarized in Table 1.

[0063] Table 1. Simulation summary of hybrid impedance matching topology working at different frequencies of power amplifier output voltage

[0064] Power amplifier output 200Hz, 220V 500Hz, 220V time 0~20ms 20ms~40ms Load side reactive power 1949 Var 6120Var Load side active 1861W 2388W Load side power factor 0.69 0.36 Amplifier side reactive power -1Var 91Var Amplifier side active -1936W -2168W Power factor of power supply side current 1 1

[0065] See also Figure 4 , in the interval of 0ms to 20ms, the power amplifier output voltage is 220V with an effective value and a frequency of 300Hz to the electroacoustic transducer load, but due to the presence of a large number of equivalent inductive loads on the electroacoustic transducer load side, the current at the electroacoustic transducer end lags behind the voltage, and the power factor is 0.54, which greatly reduces the power output capacity of the power amplifier. However, on the power amplifier side using the hybrid impedance matching topology, the output voltage and current of the power amplifier are matched to the same phase, and the power factor is increased to 1, which improves the output capacity of the power amplifier. The output voltage of the power amplifier is increased to 380V at 20ms and lasts until 40ms. After a short transient process (5ms), the hybrid impedance matching topology can also make the current and voltage on the power amplifier side in the same phase, and the power factor is 1. This simulation example proves that the impedance matching topology of the present invention can still work normally when the output voltage value of the power amplifier changes, and has the function of automatic adjustment. The results of this simulation example are summarized in Table 2.

[0066] Table 2 Simulation summary of hybrid impedance matching topology when the power amplifier output voltage value changes

[0067] Power amplifier output 220V, 300HZ 380V, 300HZ time 0~20ms 20ms~40ms Load side reactive power 3377Var 9009Var Load side active 2150W 5737W Load side power factor 0.54 0.54 Amplifier side reactive power 146Var 93Var Amplifier side active -2076W -6181W Power factor of power supply side current 1 1

[0068] Finally, the above two sets of simulation results verify that the hybrid impedance matching topology structure proposed in the present invention can automatically match the impedance of the electroacoustic transducer load in a wider frequency band to improve the power factor of the power amplifier, thereby ultimately improving the output capacity of the amplifier.

Claims

1. A transducer based on a hybrid impedance matching topology, characterized in that: include: An active converter, the input side of which is connected to a power amplifier; A capacitor module connected to the output side of the active converter; Wherein, the capacitor module is connected to the electroacoustic transducer, and when the operating frequency of the electroacoustic transducer is minimum, the capacitive reactance of the capacitor module is equal to the inductive reactance of the electroacoustic transducer; The active converter is a single-module active converter or a multi-module active converter; the single-module active converter includes a full-bridge inverter and a filter circuit, and the midpoints of the two bridge arms of the full-bridge inverter are connected to the filter circuit; the multi-module active converter includes a plurality of cascaded single-module active converters; The active converter is used to perform precise impedance matching. The specific implementation process includes: collecting the voltage and current of the series circuit of the capacitor module and the electroacoustic transducer, calculating the reactive power that needs to be compensated, and controlling the active converter to generate a corresponding matching voltage to achieve impedance matching.

2. The transducer based on the hybrid impedance matching topology structure according to claim 1, characterized in that: The capacitor module includes a plurality of parallel branches, and each branch includes a plurality of capacitors connected in series.

3. A control method for a transducer based on a hybrid impedance matching topology structure according to claim 1 or 2, characterized in that: include: 1) For the combined voltage v L , power amplifier output current i L Perform a delay of 1 / 4T and get v L D and L D , calculate the instantaneous power of the combined circuit of the capacitor module and the electroacoustic transducer in series after rough matching: Among them, p L is the instantaneous active power, q L is the instantaneous reactive power; T is the period of the power amplifier output voltage; v L is the sum of the voltage across the capacitor module and the voltage across the active converter; 2) For p L ,q L Perform low-pass filtering to obtain Use the following formula to calculate the active power P L and reactive power Q L : 3) The power amplifier output voltage v Co Perform a delay of 3 / 4T to get v Co D , use the following formula to calculate the reference voltage v AB *: 4) Set the reference voltage v AB *The control signal for driving the active converter power device is generated through feedforward control and feedback control.

4. The control method according to claim 3, characterized in that: The specific implementation process of step 4) includes: The reference voltage v AB * and feedforward control coefficient K f Multiply them to get the first result; The reference voltage v AB * The actual output voltage v of the active converter AB The difference multiplied by the feedback control coefficient G _PR (s), and obtain the second result; The sum of the first result and the second result is modulated by SPWM to generate a control signal for driving an active converter power device; Among them, G _PR The calculation formula of (s) is: ω0 is the output voltage v Co Angular frequency; K P1 , K P2 , …, K Pn is the proportional coefficient of segmented resonance control; K I1 , K I2 , …, K In is the integral coefficient of segmented resonance control; ω c is the angular frequency bandwidth of the segmented resonance control; ω2, ω3, …, ω n is the segmented frequency point of segmented resonance control; S1, S2, ..., S n It is the symbol of the working range of segmented resonant control.

5. The control method according to claim 3, characterized in that: The DC voltage V of the active converter dc The product of the modulation factor m is greater than the reference voltage v AB *Amplitude, when the power amplifier output voltage frequency and amplitude are maximum, v AB *Get the maximum value.

6. The control method according to claim 5, characterized in that: The modulation coefficient is 0.

9.

7. The control method according to claim 3, characterized in that: Before step 1), it also includes: The zero-crossing comparison method is used to calculate the power amplifier output voltage v in real time Co angular frequency ω0 and period T.

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