CN111786640A - A kind of automatic compression ratio control device and control method of power amplifier - Google Patents

Abstract

The invention discloses an automatic compression ratio control device and a control method for a power amplifier, which solve the problem that the traditional power amplifier cannot continuously output sound because of overhigh temperature. The automatic compression ratio control device of the power amplifier comprises a microcontroller, and a power input terminal, a first analog-to-digital converter, a digital signal processor, a digital-to-analog converter, a power amplifier and a power output terminal of the compressor, which are electrically connected in sequence, wherein the digital signal processor and the power amplifier are both electrically connected with the microcontroller, a radiator temperature detector is arranged between the microcontroller and the power amplifier, the digital signal processor is integrated with an RMS voltage detector, a level converter, a level comparator, a gain smooth updater and a gain controller, which are electrically connected in sequence, and signals input by the first analog-to-digital converter respectively enter the RMS voltage detector and the gain controller. The invention is applied to the technical field of electronics.

Description

A kind of automatic compression ratio control device and control method of power amplifier

technical field

The invention relates to an automatic compression ratio control device and a control method of a power amplifier, in particular to a device and a control method for the automatic compression ratio of the power amplifier to be controlled by temperature and output power.

Background technique

Existing class AB power amplifiers have large power dissipation and cause serious heat generation. In order to protect the power amplifier device from being damaged due to excessive temperature, an over-temperature protection circuit is often used to protect the power amplifier device. It can directly turn off the power amplifier when the temperature exceeds a certain set critical temperature, so that the power amplifier device cannot continue to output sound, and the interruption of sound output affects the user experience.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to solve the traditional automatic compression ratio control device and control method of a power amplifier that cannot continue to output sound due to excessive temperature.

The technical scheme adopted by the present invention is: the present invention includes an automatic compression ratio control device and a control method of a power amplifier, and the automatic compression ratio control device of the power amplifier includes a microcontroller and a power input terminal of the compressor electrically connected in sequence. , a first analog-to-digital converter, a digital signal processor, a digital-to-analog converter, a power amplifier and a power output terminal, the digital signal processor and the power amplifier are both electrically connected to the microcontroller, and the A radiator temperature detector is arranged between the microcontroller and the power amplifier, and the digital signal processor is integrated with an RMS voltage detector, a level converter, a level comparator, and a smooth gain update that are electrically connected in sequence. The first analog-to-digital converter input signal enters the RMS voltage detector and the gain controller, respectively.

Further, the word signal processor is also integrated with a compression ratio input module, a start control time module, a release time module and a start threshold module that are all electrically connected to the microcontroller. The start control time module and the release time module are both signally connected to the gain smoothing updater, and the start threshold value module is signally connected to the level comparator.

Further, an anti-aliasing filter is also arranged between the power input terminal and the analog-to-digital converter, and an analog low-pass filter is also arranged between the digital-to-analog converter and the power amplifier.

Further, an output voltage detector and an output current detector are arranged in parallel between the microcontroller and the power output terminal, and are also arranged between the output voltage detector and the output current detector and the microcontroller. There are detection circuit modules.

Further, the detection circuit module includes a signal attenuator, a full-wave rectifier, a second low-pass filter and a second analog-to-digital converter that are electrically connected in sequence.

Further, the automatic compression ratio control method of the power amplifier includes the following steps:

a. The input terminal inputs the signal into the first analog-to-digital converter after passing through the anti-aliasing filter, and the first analog-to-digital converter converts the analog signal into a digital signal and inputs it to the RMS voltage detector;

b. The RMS voltage detector performs effective value detection on the signal output by the analog-to-digital converter, and inputs the detected value to the level converter;

c. The level converter converts the value input by the RMS voltage detector into a value with the same unit as the startup threshold value module, and the converted value and the value of the startup threshold value module are transferred to the level comparator for comparison between the two;

d. The gain smoothing updater manually inputs the parameters of the start control time module and the release time module through the microcontroller, and automatically updates the parameters of the compression ratio input module through the microcontroller, and then the gain smoothing updater updates the parameters of the gain controller;

e. When the compressor is not activated, the output result of the level comparator is false, that is, the output value of the level converter is less than the value of the activation threshold module, and the previous state is the straight-through state, then the output of the level comparator is smooth and updated. The value of the compressor makes the gain controller in the direct state, and the compressor is not activated at this time;

f. When the compressor starts to start, the output result of the level comparator is true, that is, the output value of the level converter is greater than the value of the start threshold module, then the output control gain can be obtained by the following equation: gain_dB(n)=( (in_dBu(n)-thd_dBu)*(1/R)+thd_dBu)-in_dBu(n); where gain_dB(n) is the gain after compression, in_dBu(n) input level, thd_dBu threshold level, R is micro The compression ratio calculated by the controller, the gain smoothing can be calculated by the following equation env(n)=(1-theta)*env(n-1)+theta*f(n); where f=10(gain_dB(n)/ 20), the smoothed gain of env(n), the theta smoothing coefficient, can be calculated from the start-up time and release time.

Further, the microcontroller in step d automatically updates the parameters of the compression ratio input module and includes the following steps: d1. Both the output voltage detector and the output current detector are sent to the microcontroller for compression ratio processing after passing through the detection circuit module; d2. The automatic compression ratio is controlled by temperature and output power. At this time, the compression ratio is automatically calculated in the microcontroller according to the following equation, R=K1+K2*(T-T0)+K3*(P-P0), where K1 , K2, K3 are self-defined coefficients, T is the radiator temperature, T0 is the initial temperature, P is the output power, P0 is the initial output power, when T<T0, (T-T0)<0, the temperature does not affect the ratio R, the compression ratio R remains unchanged, when T>T0, (T-T0)>0, the radiator temperature automatically controls the compression ratio R; when P<P0, (P-P0)<0, the temperature does not affect the ratio R, The compression ratio R remains unchanged. When P>P0, (P-P0)>0, the output power automatically controls the compression ratio R.

Further, in the step d1, the output voltage detector and the output current detector are both attenuated by the signal attenuator in the detection circuit module, then input to the full-wave rectifier for full-wave rectification, and then input to the low-pass filter 2 and then input. to the second analog-to-digital converter, and finally output to the microcontroller through the second analog-to-digital converter for compression ratio processing

The beneficial effects of the present invention are as follows: the present invention is implemented by the method of combining software and hardware, and the signal input by the input terminal of the compressor is input to the analog-to-digital converter through analog low-pass anti-aliasing filtering, and from the analog-to-digital converter to the digital The signal processor is processed, and after the processing is completed, it is output to the digital-to-analog converter, and the digital-to-analog converter is output to the analog low-pass filter, which is restored to an analog signal. The analog signal is output through the power amplifier, and the microcontroller controls each manual parameter. Therefore, the present invention automatically adjusts the compression ratio of the compressor to control the size of the input signal by checking the size of the input signal, the output power and the temperature of the radiator temperature detector, thereby controlling the working temperature of the power amplifier, avoiding The output of traditional power amplifier devices is interrupted due to over-temperature protection.

Description of drawings

Fig. 1 is the principle schematic diagram of the present invention;

Fig. 2 is the schematic diagram of control gain;

FIG. 3 is a schematic diagram of the principle of the detection circuit module.

Detailed ways

As shown in FIG. 1 to FIG. 3 , in this embodiment, the present invention includes an automatic compression ratio control device and a control method for a power amplifier. The automatic compression ratio control device for a power amplifier includes a microcontroller 1 and is electrically connected in sequence. The power input terminal 2 of the compressor, the first analog-to-digital converter 3, the digital signal processor 4, the digital-to-analog converter 5, the power amplifier 6 and the power output terminal 7, the digital signal processor 4 and the power amplifier 6 are electrically connected to the microcontroller 1, and a heat sink temperature detector 8 is provided between the microcontroller 1 and the power amplifier 6, and the digital signal processor 4 is integrated with sequential electrical The connected RMS voltage detector 41, level converter 42, level comparator 43, gain smoothing updater 44 and gain controller 45, the signal input by the first analog-to-digital converter 3 respectively enters the RMS voltage detector 41 and the gain controller 45 .

In this embodiment, the word signal processor is further integrated with a compression ratio input module 46, a start control time module 47, a release time module 48 and a start threshold value module 49 that are all electrically connected to the microcontroller 1, The compression ratio input module 46, the start-up time module 47, and the release time module 48 are all signal-connected to the gain smoothing updater 44, and the start-up threshold module 49 is signal-connected to the level comparator 43, The activation value of the activation threshold value module 49 is the threshold of the compressor activation, the compression ratio input module 46 is the ratio of the size of the compressor attenuation, and the input activation time of the activation time module 47 is the compressor boost or attenuation. The time required to reach the target level, the input release time of the release time module 48 is the release time required for the compressor to return to unity gain, and the gain smoothing updater 44 is used to update the gain smoothing, which has overcome the compressor startup time parameter Mutation causes mutation noise.

In this embodiment, an anti-aliasing filter 9 is further arranged between the power input terminal 2 and the analog-to-digital converter, and an analog-to-analog converter 5 is also arranged between the digital-to-analog converter 5 and the power amplifier 6 Low pass filter 10.

In this embodiment, an output voltage detector 11 and an output current detector 12 are arranged in parallel between the microcontroller 1 and the power output terminal 7 , and the output voltage detector 11 and the output current detector 12 are connected in parallel. A detection circuit module is also arranged between 12 and the microcontroller 1 .

In this embodiment, the detection circuit module includes a signal attenuator 13 , a full-wave rectifier 14 , a second low-pass filter 15 and a second analog-to-digital converter 16 that are electrically connected in sequence.

In this embodiment, the control method of the automatic compression ratio control device includes the following steps:

a. The input terminal inputs the signal into the first analog-to-digital converter 3 after passing the anti-aliasing filter 9, and the first analog-to-digital converter 3 converts the analog signal into a digital signal and inputs it to the RMS voltage detector 41;

b. The RMS voltage detector 41 performs effective value detection on the signal output by the analog-to-digital converter, and inputs the detected value to the level shifter 42;

c. The level converter 42 converts the value input by the RMS voltage detector 41 into a value with the same unit as the activation threshold value module 49, and the converted value and the value of the activation threshold value module 49 are passed to the level comparator 43 for the conversion of the two. Compare;

d. The gain smoothing updater 44 manually inputs the parameters of the start control time module 47 and the release time module 48 through the microcontroller 1, and automatically updates the parameters of the compression ratio input module 46 through the microcontroller 1, and then the gain smoothing updater 44 pairs The gain controller 45 performs parameter update;

e. When the compressor is not activated, the output result of the level comparator 43 is false, that is, the output value of the level converter 42 is smaller than the value of the activation threshold value module 49, and the previous state is the straight-through state, then the level comparator 43 outputs To the value of the gain smoothing updater, the gain controller 45 is in a straight-through state, and the compressor is not activated at this time;

f. When the compressor starts to start, the output result of the level comparator 43 is true, that is, the output value of the level converter 42 is greater than the value of the start threshold value module 49, then the output control gain can be obtained by the following equation: gain_dB(n )=((in_dBu(n)-thd_dBu)*(1/R)+thd_dBu)-in_dBu(n); where gain_dB(n) is the compressed gain, in_dBu(n) input level, thd_dBu threshold level, R is the compression ratio calculated by microcontroller 1, and gain smoothing can be calculated by the following equation env(n)=(1-theta)*env(n-1)+theta*f(n); where f=10(gain_dB (n)/20), the smoothed gain of env(n), the theta smoothing coefficient, which can be calculated from the start-up time and release time.

In this embodiment, the microcontroller 1 in step d automatically updates the parameters of the compression ratio input module 46 including the following steps: d1. Both the output voltage detector 11 and the output current detector 12 pass through the detection circuit module and are sent to the microcomputer. Controller 1 performs compression ratio processing; d2. Automatic compression ratio is controlled by temperature and output power. At this time, the compression ratio is automatically calculated in microcontroller 1 according to the following equation, R=K1+K2*(T -T0)+K3 *(P-P0), where K1, K2, K3 are custom coefficients, T is the radiator temperature, T0 is the initial temperature, P is the output power, P0 is the initial output power, when T<T0, (T- When T0)<0, the temperature does not affect the ratio R, and the compression ratio R remains unchanged. When T>T0, (T-T0)>0, the radiator temperature automatically controls the compression ratio R; when P<P0, (P-P0) When <0, the temperature does not affect the ratio R, and the compression ratio R remains unchanged. When P>P0, (P-P0)>0, the output power automatically controls the compression ratio R.

In this embodiment, in the step d1, the output voltage detector 11 and the output current detector 12 are both attenuated by the signal attenuator 13 in the detection circuit module, and then input to the full-wave rectifier 14 for full-wave rectification, and then input to the signal attenuator 13. The second low-pass filter 15 is then input to the second analog-to-digital converter 16, and finally output to the microcontroller 1 through the second analog-to-digital converter 16 for compression ratio processing.

The present invention is applied in the field of electronic technology.

Although the embodiments of the present invention are described in terms of actual solutions, they do not limit the meaning of the present invention. For those skilled in the art, modifications to the embodiments and combinations with other solutions are obvious to those skilled in the art from this specification. .

Claims (8)

1. An automatic compression ratio control device of a power amplifier, characterized in that: it comprises a microcontroller (1), and a power input terminal (2), a first analog-to-digital converter (3), a digital signal processor (4), a digital-to-analog converter (5), a power amplifier (6) and a power output terminal (7) which are electrically connected in sequence, the digital signal processor (4) and the power amplifier (6) are both electrically connected with the microcontroller (1), a radiator temperature detector (8) is arranged between the microcontroller (1) and the power amplifier (6), the digital signal processor (4) is integrated with an RMS voltage detector (41), a level converter (42), a level comparator (43), a gain smooth updater (44) and a gain controller (45) which are electrically connected in turn, the signal input by the first analog-to-digital converter (3) enters the RMS voltage detector (41) and the gain controller (45), respectively.

2. The automatic compression ratio control apparatus of a power amplifier according to claim 1, characterized in that: the digital signal processor is further integrated with a compression ratio input module (46), an activation time module (47), a release time module (48) and a starting threshold module (49) which are all electrically connected with the microcontroller (1), the compression ratio input module (46), the activation time module (47) and the release time module (48) are all in signal connection with the gain smooth updater (44), and the starting threshold module (49) is in signal connection with the level comparator (43).

3. The automatic compression ratio control apparatus of a power amplifier according to claim 2, characterized in that: an anti-aliasing filter (9) is further arranged between the power input terminal (2) and the analog-to-digital converter, and an analog low-pass filter (10) is further arranged between the digital-to-analog converter (5) and the power amplifier (6).

4. The automatic compression ratio control apparatus of a power amplifier according to claim 3, characterized in that: an output voltage detector (11) and an output current detector (12) are arranged between the microcontroller (1) and the power output terminal (7) in parallel, and a detection circuit module is further arranged between the output voltage detector (11) and the output current detector (12) and the microcontroller (1).

5. The automatic compression ratio control apparatus of a power amplifier according to claim 4, characterized in that: the detection circuit module comprises a signal attenuator (13), a full-wave rectifier (14), a second low-pass filter (15) and a second analog-to-digital converter (16) which are electrically connected in sequence.

6. A control method of an automatic compression ratio control apparatus including the power amplifier of claim 5, characterized by comprising the steps of:

a. the input terminal inputs the signal into a first analog-to-digital converter (3) after passing through an anti-aliasing filter (9), and the first analog-to-digital converter (3) converts the analog signal into a digital signal and inputs the digital signal into an RMS voltage detector (41);

an RMS voltage detector (41) detects the effective value of the analog-to-digital converter according to the output signal of the analog-to-digital converter and inputs the detected value to a level converter (42);

c. the level converter (42) converts the value input by the RMS voltage detector (41) into the value with the same unit as that of the starting threshold module (49), and the converted value and the value of the starting threshold module (49) are transmitted into the level comparator (43) to be compared;

d. the gain smooth updater (44) manually inputs the parameters of the start control time module (47) and the release time module (48) through the microcontroller (1), automatically updates the parameters of the compression ratio input module (46) through the microcontroller (1), and then the gain smooth updater (44) updates the parameters of the gain controller (45);

e. when the compressor is not started, the output result of the level comparator (43) is false, namely the output value of the level converter (42) is smaller than the value of the starting threshold module (49), and the previous state is a through state, the value output to the smooth updater by the level comparator (43) enables the gain controller (45) to be in the through state, and the compressor is not started at the moment;

f. when the compressor starts, the output result of the level comparator (43) is true, that is, the output value of the level shifter (42) is greater than the value of the start threshold module (49), then the output control gain can be obtained by the following equation: gain _ db (n) ((in _ dbu (n) -thd _ dBu) ((1/R) + thd _ dBu) -in _ dbu (n)); wherein gain _ db (n) is the compressed gain, in _ dbu (n) input level, thd _ dBu threshold level, and R is the compression ratio calculated by the microcontroller (1), and gain smoothing may be calculated by the following equation, (1-theta) env (n-1) + theta f (n); wherein f is 10(gain _ db (n)/20), env (n) is the smoothed gain, and the theta smoothing coefficient can be calculated by the control starting time and the release time.

7. The automatic compression ratio control method of a power amplifier according to claim 6, characterized in that: the microcontroller (1) in step d automatically updating the parameters of the compression ratio input module (46) comprises the following steps:

d1. the output voltage detector (11) and the output current detector (12) are transmitted to the microcontroller (1) through the detection circuit module to be subjected to compression ratio processing; d2. the automatic compression ratio is controlled by temperature and output power, and the compression ratio is automatically calculated in the microcontroller (1) according to the following equation, wherein R is K1+ K2 (T-T0) + K3 (P-P0), K1, K2 and K3 are self-defined coefficients, T is the temperature of a radiator, T0 is the starting temperature, P is the output power, P0 is the starting output power, when T < T0, (T-T0) <0, the temperature does not affect the ratio R, the compression ratio R is kept unchanged, and when T > T0, (T-T0) >0, the temperature of the radiator automatically controls the compression ratio R; when P < P0, (P-P0) <0, the temperature does not affect the ratio R, the compression ratio R is kept unchanged, and when P > P0, (P-P0) >0, the output power automatically controls the compression ratio R.

8. The automatic compression ratio control method of a power amplifier according to claim 7, characterized in that: in the step d1, the output voltage detector (11) and the output current detector (12) are attenuated by the signal attenuator (13) in the detection circuit module, input to the full-wave rectifier (14) for full-wave rectification, then input to the low-pass filter II (15), input to the second analog-to-digital converter (16), and finally output to the microcontroller (1) through the second analog-to-digital converter (16) for compression ratio processing.

Images