Underwater sound power amplifier closed-loop control circuit and sonar transmitter

Abstract

The invention provides an underwater sound power amplifier closed-loop control circuit and a sonar transmitter. The underwater sound power amplifier closed-loop control circuit comprises a power supply circuit, a power amplifier circuit, a matching circuit, an acquisition circuit and an STM32 module circuit, the power supply circuit provides a stable power supply for the power amplifier circuit, the acquisition circuit and the STM module circuit; the acquisition circuit monitors voltage and current signals of a load in real time and converts the voltage and current signals into digital signals; the power amplifier circuit amplifies a control signal output by the STM32 module circuit to drive a load; the STM32 module circuit is used for processing digital signals and adjusting control signals in a closed-loop manner; the matching circuit is connected with the power amplifier circuit and the load; and signals amplified by the power amplifier circuit are filtered, and load matching is carried out at the same time. Output voltage signals can be monitored in real time, the duty ratio and the modulation degree are controlled through the main control chip to achieve closed-loop feedback, and the output voltage is stabilized within a certain range.

Description

Technical Field

[0001] The present invention relates to the technical field of sonar, and in particular to an underwater acoustic power amplifier closed-loop control circuit and a sonar transmitter. Background Art

[0002] The power amplifier is an important part of the transmitter, and is a unit that realizes power amplification, impedance transformation, and matching filtering. The sonar transmitter is an important part of the active sonar equipment, and the power amplifier unit is usually the largest unit in the transmitter and consumes the most power. Its performance has a great impact on the range, working bandwidth, and reliability of the entire system.

[0003] The output of existing underwater acoustic class D amplifiers is usually open-loop controlled, and the output waveform and voltage are limited by the amplifier matching circuit. Once the matching circuit is determined, the output voltage at each frequency is determined. Sometimes, the transducer voltage response curve fluctuates greatly with frequency, making it difficult to design a good matching circuit.

[0004] Therefore, a closed-loop feedback power amplifier transmitter is needed to solve these problems. Summary of the invention

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide an underwater acoustic power amplifier closed-loop control circuit and a sonar transmitter.

[0006] According to the present invention, a closed-loop control circuit of an underwater acoustic power amplifier includes: a power supply circuit, a power amplifier circuit, a matching circuit, a collection circuit, and an STM32 module circuit;

[0007] The power supply circuit provides a stable power supply for the power amplifier circuit, the acquisition circuit, and the STM module circuit; the acquisition circuit monitors the voltage and current signals of the load in real time and converts them into digital signals; the power amplifier circuit amplifies the control signal output by the STM32 module circuit to drive the load; the STM32 module circuit processes the digital signal and adjusts the control signal in a closed loop; the matching circuit connects the power amplifier circuit and the load; the signal amplified by the power amplifier circuit is filtered, and load matching is performed at the same time.

[0008] Preferably, the power supply circuit includes an AC-DC power supply, a DC-DC conversion circuit and a filter circuit;

[0009] The AC-DC power supply outputs the 48V power supply required by the power amplifier circuit;

[0010] The DC-DC conversion circuit outputs the 12V power supply required by the acquisition circuit, and the 5V and 3.3V power supplies required by the STM32 module;

[0011] The filter circuit filters the output end of the DC-DC conversion circuit.

[0012] Preferably, the acquisition circuit includes a voltage measurement circuit and a current measurement circuit;

[0013] The voltage measurement circuit includes an operational amplifier U12A, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, and a capacitor C26;

[0014] The inverting input terminal of the operational amplifier U12A is connected to the input voltage signal through the resistor R17, one end of the capacitor C26 is connected to the input voltage signal, and the other end of the capacitor C26 is grounded;

[0015] A resistor R16 and a resistor R13 are connected in series between the output terminal and the inverting input terminal of the operational amplifier U12A, and the port where the resistor R13 and the resistor R16 are connected is connected to the output terminal P8 through the resistor R15 and the resistor R14;

[0016] The non-inverting input terminal of the operational amplifier U12A is connected to VOUT through the resistor R12, the resistor R10, and the resistor R9, and is grounded through the resistor R11 at the port where the resistor R10 and the resistor R12 are connected;

[0017] The current measurement circuit includes an operational amplifier U12B, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R14, a resistor R26, a resistor R27, a capacitor C27, and a sampling resistor;

[0018] The inverting input terminal of the operational amplifier U12B is connected to the input current signal through the resistor R27, one end of the capacitor C27 is connected to the input current signal, and the other end of the capacitor C27 is grounded;

[0019] A resistor R21 and a resistor R26 are connected in series between the output terminal and the inverting input terminal of the operational amplifier U12B, and the port where the resistor R21 and the resistor R26 are connected is connected to the output terminal P8 through a resistor R24;

[0020] The non-inverting input terminal of the operational amplifier U12B is connected to VOUT through resistors R22 and R23, and the port where the resistors R22 and R23 are connected is grounded through a resistor R25;

[0021] One end of the sampling resistor is connected to VOUT, and the other end of the sampling resistor is connected to the output end of the operational amplifier U12B through the resistor R24 ​​and the resistor R21.

[0022] Preferably, the matching circuit is composed of a passive second-order Butterworth filter circuit, including a resistor R0, a resistor R5, a power inductor L1, a transformer L4, a polypropylene capacitor C2 and a polypropylene capacitor C3;

[0023] The positive electrode of the control signal enters the circuit through the resistor R0 and is connected in series with one end of the power inductor L1. The other end of the power inductor L1 is connected in series with one end of the polypropylene capacitor C2. The other end of the polypropylene capacitor C2 is connected in series with one end of the transformer L4, one end of the polypropylene capacitor C3, and one end of the resistor R5. The other end of the control signal is connected in series with the other end of the transformer L4, the other end of the polypropylene capacitor C3, and the other end of the resistor R5.

[0024] Preferably, the STM32 module communicates with the host computer through a serial port, receives system status information, and sends control instructions. The STM32 module circuit stores a sine wave table; and adjusts the value of the waveform in the sine wave table in real time according to the collected signal, and outputs a signal of a matching circuit.

[0025] Preferably, the STM32 module detects that the load output voltage does not reach the expected voltage, changes the signal size given to the power amplifier circuit by changing the duty cycle and the modulation degree, and adjusts the waveform data parameters of the input signal to change the output voltage distortion.

[0026] Preferably, the power amplifier circuit includes a signal generation and modulation circuit and a power amplifier;

[0027] The signal generation and modulation circuit includes an error amplifier, a modulation circuit, a dead time and an inverter; the power amplifier includes a drive circuit and two MOS tubes.

[0028] The error amplifier compares the input signal with the feedback signal to generate an error signal;

[0029] The modulation circuit performs modulation processing on the error signal;

[0030] The dead time processes the modulated PWM signal to avoid cross conduction in the power amplifier stage;

[0031] The PWM signal is processed by the inverter to generate a complementary PWM signal, which is processed by the drive circuit to drive the switch tube of the power amplifier stage;

[0032] The MOS tube performs a switching operation according to the duty cycle of the PWM signal to convert the DC power supply into an AC signal, thereby amplifying the input audio signal.

[0033] The invention provides a sonar transmitter, comprising the underwater acoustic power amplifier closed-loop control circuit.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention can monitor the output voltage signal in real time, and realize closed-loop feedback by controlling the duty cycle and modulation index through the main control chip, so as to stabilize the output voltage within a certain range. At the same time, different expected parameter values ​​can be set at different frequencies to compensate for the problem of insufficient load emission voltage response and reduce the difficulty of matching circuits to increase gain at certain frequency points. At the same time, the input signal of the power amplifier is generated by the main control chip itself and can be modified in real time.

[0036] 2. The present invention adds a fast distortion detection method, which can quickly and simply determine whether the output voltage meets the distortion requirement through the relationship between the output voltage peak value and the effective value.

[0037] 3. The present invention reduces the size of the whole machine by selecting a suitable planar transformer. Meanwhile, the planar transformer has an adjustable leakage inductance, which is conducive to miniaturization design. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0039] Figure 1 is the transmitter block diagram;

[0040] Figure 2 It is a voltage and current acquisition circuit;

[0041] Figure 3 It is the power amplifier signal generation and amplification;

[0042] Figure 4 is a 2nd order Butterworth filter; DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0044] Reference Figure 1 As shown, a principle block diagram of a voltage feedback class D power amplifier in an embodiment provided by the present invention includes a power supply circuit, a power amplifier circuit, a matching circuit, a collection circuit, and an STM32 module circuit.

[0045] The power supply circuit provides a stable power supply for the power amplifier circuit, the acquisition circuit, and the STM module circuit; the acquisition circuit monitors the voltage and current signals of the transducer load in real time and converts them into digital signals; the functional circuit amplifies the control signal output by the STM32 module circuit and drives the transducer load; the STM32 module circuit processes the digital signal, adjusts the control signal, ensures the stability of the output voltage and reduces harmonic distortion. The matching circuit is used to filter the model amplified by the power amplifier circuit, and matches it with the transducer load at the same time, plays the role of impedance transformation, tuning, and improving efficiency; the transducer load is the final output device, which converts the electrical signal output by the power amplifier circuit into sound waves or other forms of energy to complete the final output of the signal.

[0046] In a preferred embodiment, the power supply circuit includes an AC-DC power supply, a storage circuit, a DC-DC conversion circuit and a filtering circuit; wherein the AC-DC power supply outputs the 48V power supply required by the power amplifier circuit, and the DC-DC conversion circuit outputs the 12V power supply required by the acquisition circuit through the filtering circuit, and the 5V and 3.3V power supplies required by the STM32 module.

[0047] The acquisition circuit is used to collect the emission voltage and distortion of the transducer. The acquisition circuit includes the acquisition of true effective value and peak value. Figure 2 As shown, the acquisition circuit is composed of a JFET type operational amplifier to form a differential acquisition circuit. The transmitted voltage signal is scaled down and then fed to the ADC through RC filtering to obtain peak voltage data. At the same time, the filtered signal is fed to the effective value voltage acquisition chip to obtain the effective value, and then the distortion is obtained by the ratio of the effective value to the peak value. The acquisition circuit collects the output current through a precision sampling resistor to determine whether it is overcurrent, and gives a signal to the main control chip to control the shutdown of the power amplifier, thereby playing the role of overcurrent protection and limiting the maximum current.

[0048] The working principle of the acquisition circuit is further explained in detail below.

[0049] The acquisition circuit is mainly composed of two operational amplifiers, which are used for voltage measurement and current measurement respectively.

[0050] Voltage measurement part:

[0051] The input voltage signal enters the inverting input terminal (pin 1) of the operational amplifier U12A through resistor R17. Capacitor C26 is connected in parallel with resistor R17 to form a low-pass filter for filtering high-frequency noise. The non-inverting input terminal (pin 3) of the operational amplifier U12A is grounded through resistor R12. Resistors R11, R12, R13 and R14 form a voltage follower for buffering the input signal. Resistors R15 and R16 are used to set the gain of the amplifier. The output terminal (pin 2) of the operational amplifier U12A outputs a voltage signal through resistor R14. The output signal is output through the P8 terminal and can be connected to subsequent processing circuits or display devices.

[0052] Current test part:

[0053] The input current passes through a precision sampling resistor (0.5Ω), and the resulting voltage drop enters the inverting input (pin 7) of the operational amplifier U12B through resistor R27. Capacitor C27 is connected in parallel with resistor R27 to form a low-pass filter for filtering out high-frequency noise. The non-inverting input (pin 6) of the operational amplifier U12B is grounded through resistor R22. Resistors R25, R26, R21, and R22 form a voltage follower for buffering the input signal. Resistors R23 and R24 are used to set the gain of the amplifier. The output (pin 5) of the operational amplifier U12B outputs a voltage signal through resistor R24. The output signal is output through the P8 terminal and can be connected to subsequent processing circuits or display devices.

[0054] This acquisition circuit is powered by a ±12V power supply and provides bias current for the operational amplifier through resistors R9 and R10.

[0055] The matching circuit is used to filter the signal amplified by the power amplifier and match it with the transducer load, which plays a role in impedance transformation, tuning and improving efficiency. The matching circuit includes an adjustable leakage inductance planar transformer. It replaces the matching inductor and reduces the number of components. Figure 4 The matching circuit is composed of a passive second-order Butterworth filter circuit, which is usually composed of a power inductor L1, a polypropylene capacitor C2 in series, a transformer L4 in parallel with a polypropylene capacitor C3. It has an out-of-band attenuation of 40dB and an in-band fluctuation of less than 3dB, which can filter out the modulated wave and restore the carrier signal.

[0056] The STM32 module is used to process the collected voltage signal, distortion signal, and generate a modulation signal for the power amplifier circuit. The host computer communicates with the STM32 module through the serial port, receives the system status information, and sends control instructions. The STM32 module circuit stores the sine wave table; at the same time, it can adjust the value of the waveform in the sine wave table in real time according to the collected signal, output a signal suitable for the matching circuit, improve the output harmonic distortion, and stabilize the voltage.

[0057] The STM32 module consists of STM32F103RCT6 and corresponding peripheral circuits. Figure 3 The STM32 module mainly realizes signal generation and modulation, and processes the collected voltage, current and other signals. When it is detected that the output voltage does not reach the expected voltage, the internal signal modulation will change the signal size given to the power amplifier circuit by changing the duty cycle and modulation degree, and adjust the waveform data parameters of the input signal to change the output voltage distortion.

[0058] Furthermore, the power amplifier circuit is composed of a driving circuit, i.e., a half-bridge driving chip, a peripheral circuit, and two MOSs, which are divided into an upper MOS tube and a lower MOS tube. Before the modulation signal is output to drive the MOS, it needs to pass through an inverter. When the upper tube is turned on, the lower tube must be turned off, and vice versa. At the same time, a reverse diode is added to the driving circuit to accelerate the discharge of the MOS.

[0059] The working principle of the power amplifier circuit is further explained below.

[0060] Reference Figure 3 As shown, the power amplifier circuit includes a signal generation and modulation circuit and a power amplifier; wherein the signal generation and modulation circuit includes an error amplifier, a modulation circuit, a dead time (delay time) and an inverter; the power amplifier includes a drive circuit and two MOS tubes.

[0061] Error amplifier: The input signal is first processed by the error amplifier. The function of the error amplifier is to compare the input signal with the feedback signal to generate an error signal.

[0062] Modulation circuit: The error signal is processed by the modulation circuit, usually using pulse width modulation (PWM) technology. The duty cycle of the PWM signal reflects the amplitude of the input signal.

[0063] Dead time (delay time): The PWM signal is processed with dead time to avoid cross conduction in the power amplifier stage, thereby reducing power loss and distortion.

[0064] Inverter: The PWM signal is processed by the inverter to generate a complementary PWM signal, which is used to drive the two switching tubes of the power amplifier stage.

[0065] Drive circuit: The complementary PWM signal is processed by the drive circuit and used to drive the switching tube of the power amplifier stage.

[0066] The switch tube performs switching operations according to the duty cycle of the PWM signal, converting the DC power supply into an AC signal, thereby amplifying the input audio signal.

[0067] The amplified signal is output through the output port to drive the load.

[0068] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A closed-loop control circuit for an underwater acoustic power amplifier, characterized in that: include: Power supply circuit, power amplifier circuit, matching circuit, acquisition circuit, and STM32 module circuit; The power supply circuit provides a stable power supply for the power amplifier circuit, the acquisition circuit, and the STM module circuit; the acquisition circuit monitors the voltage and current signals of the load in real time and converts them into digital signals; the power amplifier circuit amplifies the control signal output by the STM32 module circuit to drive the load; the STM32 module circuit processes the digital signal and adjusts the control signal in a closed loop; the matching circuit connects the power amplifier circuit and the load; the signal amplified by the power amplifier circuit is filtered, and load matching is performed at the same time.

2. The underwater acoustic power amplifier closed-loop control circuit according to claim 1, characterized in that: The power supply circuit includes an AC-DC power supply, a DC-DC conversion circuit and a filter circuit; The AC-DC power supply outputs the 48V power supply required by the power amplifier circuit; The DC-DC conversion circuit outputs the 12V power supply required by the acquisition circuit, and the 5V and 3.3V power supplies required by the STM32 module; The filter circuit filters the output end of the DC-DC conversion circuit.

3. The underwater acoustic power amplifier closed-loop control circuit according to claim 1, characterized in that: The acquisition circuit includes a voltage measurement circuit and a current measurement circuit; The voltage measurement circuit includes an operational amplifier U12A, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, and a capacitor C26; The inverting input terminal of the operational amplifier U12A is connected to the input voltage signal through the resistor R17, one end of the capacitor C26 is connected to the input voltage signal, and the other end of the capacitor C26 is grounded; A resistor R16 and a resistor R13 are connected in series between the output terminal and the inverting input terminal of the operational amplifier U12A, and the port where the resistor R13 and the resistor R16 are connected is connected to the output terminal P8 through the resistor R15 and the resistor R14; The non-inverting input terminal of the operational amplifier U12A is connected to VOUT through the resistor R12, the resistor R10, and the resistor R9, and is grounded through the resistor R11 at the port where the resistor R10 and the resistor R12 are connected; The current measurement circuit includes an operational amplifier U12B, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R14, a resistor R26, a resistor R27, a capacitor C27, and a sampling resistor; The inverting input terminal of the operational amplifier U12B is connected to the input current signal through the resistor R27, one end of the capacitor C27 is connected to the input current signal, and the other end of the capacitor C27 is grounded; A resistor R21 and a resistor R26 are connected in series between the output terminal and the inverting input terminal of the operational amplifier U12B, and the port where the resistor R21 and the resistor R26 are connected is connected to the output terminal P8 through a resistor R24; The non-inverting input terminal of the operational amplifier U12B is connected to VOUT through resistors R22 and R23, and the port where the resistors R22 and R23 are connected is grounded through a resistor R25; One end of the sampling resistor is connected to VOUT, and the other end of the sampling resistor is connected to the output end of the operational amplifier U12B through the resistor R24 ​​and the resistor R21.

4. The underwater acoustic power amplifier closed-loop control circuit according to claim 1, characterized in that: The matching circuit is composed of a passive second-order Butterworth filter circuit, including a resistor R0, a resistor R5, a power inductor L1, a transformer L4, a polypropylene capacitor C2 and a polypropylene capacitor C3; The positive electrode of the control signal enters the circuit through the resistor R0 and is connected in series with one end of the power inductor L1. The other end of the power inductor L1 is connected in series with one end of the polypropylene capacitor C2. The other end of the polypropylene capacitor C2 is connected in series with one end of the transformer L4, one end of the polypropylene capacitor C3, and one end of the resistor R5. The other end of the control signal is connected in series with the other end of the transformer L4, the other end of the polypropylene capacitor C3, and the other end of the resistor R5.

5. The underwater acoustic power amplifier closed-loop control circuit according to claim 1, characterized in that: The STM32 module communicates with the host computer through the serial port, receives the status information of the system, and sends the control instruction. The STM32 module circuit stores the sine wave table; and adjusts the value of the waveform in the sine wave table in real time according to the collected signal, and outputs the signal of the matching circuit.

6. The underwater acoustic power amplifier closed-loop control circuit according to claim 1, characterized in that: The STM32 module detects that the load output voltage does not reach the expected voltage, changes the signal size given to the power amplifier circuit by changing the duty cycle and modulation, and adjusts the waveform data parameters of the input signal to change the output voltage distortion.

7. The underwater acoustic power amplifier closed-loop control circuit according to claim 1, characterized in that: The power amplifier circuit includes a signal generation and modulation circuit and a power amplifier; The signal generation and modulation circuit includes an error amplifier, a modulation circuit, a dead time and an inverter; the power amplifier includes a drive circuit and two MOS tubes. The error amplifier compares the input signal with the feedback signal to generate an error signal; The modulation circuit performs modulation processing on the error signal; The dead time processes the modulated PWM signal to avoid cross conduction in the power amplifier stage; The PWM signal is processed by the inverter to generate a complementary PWM signal, which is processed by the drive circuit to drive the switch tube of the power amplifier stage; The MOS tube performs a switching operation according to the duty cycle of the PWM signal to convert the DC power supply into an AC signal, thereby amplifying the input audio signal.

8. A sonar transmitter, characterized in that: It comprises the underwater acoustic power amplifier closed-loop control circuit according to any one of claims 1 to 7.

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