CN113162560A - Implementation method of high-power low-distortion D-type power amplifier based on high-performance MCU - Google Patents
Implementation method of high-power low-distortion D-type power amplifier based on high-performance MCU Download PDFInfo
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Abstract
A high-power low-distortion D-type power amplifier implementation method based on a high-performance MCU belongs to the field of audio power amplifiers. The method comprises the following steps: 1) and selecting and displaying an input signal mode. 2) And preprocessing the input signal to obtain audio data. 3) And audio data is transmitted to an STM32F407 minimum system, and PWM is output to a half-bridge driving module. 4) Every two half-bridge driving modules drive one full-bridge power amplification part to realize power amplification of small signals. 5) The output of the full bridge power amplification section is filtered. 6) And sampling the current of the output passing through the low-pass filter, and feeding the current back to a minimum system. 7) Setting a digital filter according to the output feedback signal, and filtering the audio data in the step 1). 8) Repetition of 2) -7), negative feedback control of the output is realized. The invention solves the problem of noise interference at the moment of electrifying the D-type power amplifier by using lower cost, and also can compensate high frequency through the IIR, thereby solving the problem of high requirement of the D-type power amplifier on a filter when the switching frequency is low.
Description
Technical Field
The invention belongs to the field of audio power amplifiers, relates to design and manufacture of a high-performance and convenient human-computer interaction D-type audio power amplifier controlled by STM32F407, and particularly relates to a high-power low-distortion D-type power amplifier implementation method based on a high-performance MCU.
Background
The class AB power amplifier directly and linearly amplifies audio frequency by using a linear amplification area of a power tube, and the power tube has high power consumption because the voltage of the power tube is applied to the power tube. The class-D power amplifier compares an input signal with a triangular wave and drives a half bridge, and power amplification is obtained after filtering to obtain audio. Because the power tube works in the on-off state, compared with a class A linear power amplifier, a class B linear power amplifier and the like, the power tube has high efficiency and low loss, does not need a large radiator for heat dissipation, and has small overall volume. And as the manufacturing process of the field effect tube is mature day by day, the high-performance field effect tubes such as GaN, SiC and the like are applied to high-power electrical appliances, and the green, environment-friendly and portable D-type power amplifier has stronger competitiveness.
THD + N is an important index for measuring an audio power amplifier. At present, THD of most integrated power amplifiers in the market is extremely small under the condition of low power, but the THD of both a D-type power amplifier and a linear power amplifier is increased exponentially under the condition of high power. The class D power amplifier is exemplified by TDA8920, and has a maximum binaural output power of 200W, a THD of only 0.2% at 1W, but a THD of 10% at maximum power. For class AB power amplifiers, LM1875 is taken as an example, and the testing frequency is 1Khz, the THD is only 0.015% under the condition of 20W power, and the THD exceeds 1% under the condition of 30W power. And class AB power amplifier efficiency is very low, and is only 78.5% at most, and very big fin is required when high-power work. Therefore, the successful amplification of the D-type set or the class-A and class-B integrated power amplifier is not suitable for high-power occasions, and the man-machine interaction performance is poor, so that the amplified audio cannot be directly subjected to digital processing.
The design utilizes the data processing capability of the STM32F407 minimum system to directly perform operation processing on the audio signal. After comparing the input audio signal with the triangular wave of the high-grade timer, the PWM with complementary dead zone is output to drive the field effect tube. In order to make the power amplifier have higher performance under high power, a discrete field effect transistor is selected as a power transistor, so that the power of the power amplifier is doubled compared with that of the traditional integrated D-type power amplifier, the THD is smaller, and the audio amplification is more accurate.
For example, in a digital power amplifier circuit (CN104270105A) of lisanchun et al, signal processing is to separately drive class AB and class D power amplifiers with high and low frequencies, amplitude and frequency flatness is not high, and an integrated class D power amplifier circuit is used for outputting signals, which is not suitable for high-power occasions and has low efficiency and a single input mode, and is difficult to meet the requirement of multi-mode audio input. In summary, a D-class power amplifier implementation method is needed in which a high-performance MCU supports multiple output modes, outputs PWM to directly drive a full-bridge circuit, and compensates for high-pitched audio to make the amplitude-frequency characteristics flat.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for realizing a high-power low-distortion D-type power amplifier based on a high-performance MCU (microprogrammed control Unit), which solves the problems of serious distortion and poor man-machine interaction of D-type and AB-type integrated power amplifiers in high-power occasions, solves the problem of power-on instantaneous noise interference of the D-type power amplifier, and can also compensate high frequency through an IIR (infinite impulse response) to solve the problem of high requirement of the D-type power amplifier on a filter when the switching frequency is low.
In order to achieve the purpose, the invention adopts the technical scheme that:
the implementation method is realized based on a system module, wherein the system module comprises an STM32F407 minimum system, an audio Bluetooth module, an SD card module, a USB flash disk module, a half-bridge driving module, an MOSFET full-bridge power amplification part, an LCD display module, an audio analog signal amplification module, a word stock storage module, a voltage reduction auxiliary power supply system, a current sampling module, an IIR digital filter, a diaphragm loudspeaker and a plasma loudspeaker. The audio Bluetooth module is connected with the STM32F407 minimum system through an I2S communication protocol, the SD card module is connected with the STM32F407 minimum system through SDIO, the U disk module is connected with the STM32F407 minimum system through a USB bus, and the audio analog signal amplification module is connected with the STM32F407 minimum system through an ADC. The half-bridge driving module is connected with the STM32F407 minimum system. The full-bridge power amplification part inputs a driving signal through a half-bridge driving module, the full-bridge power amplification part is connected with an INA282 current sampling module after passing through a low-pass filter, the current sampling module is connected with a diaphragm loudspeaker, and meanwhile, the current sampling module is communicated with an STM32F407 minimum system through an IIR digital filter; the full-bridge power amplification part is also connected with the plasma loudspeaker through a high-pass filter. The word stock storage module is connected with the STM32F407 minimum system through the SPI. The voltage-reducing auxiliary power supply system comprises a 3.3V voltage-reducing auxiliary power supply system, a 5V voltage-reducing auxiliary power supply system and a 2V voltage-reducing auxiliary power supply system, wherein the 3.3V voltage-reducing auxiliary power supply system outputs 3.3V for supplying power to an STM32F407 minimum system, an SD card module, an LCD touch display module, a word stock storage module, an audio analog signal amplification module and an INA282 current sampling module; the 5V voltage reduction auxiliary power supply system outputs 5V to supply power for the voltage reduction auxiliary power supply module, the USB flash disk module, the audio Bluetooth module and the half-bridge driving module; the 12V voltage reduction auxiliary power supply system outputs 12V power for the voltage reduction auxiliary power supply system and the half-bridge driving module. The implementation method specifically comprises the following steps:
first, the selection and display of the play mode.
Firstly, an input signal mode is selected and displayed through an LCD touch display module. The input signal mode comprises U disk input, SD card input, analog audio signal input and audio Bluetooth input. The Chinese character display is realized by communicating a character library storage module with an STM32F407 minimum system, acquiring a character library and displaying the character library on an LCD touch display module.
And secondly, preprocessing the input signal.
2.1) inputting to a USB flash disk, enabling a USB flash disk module to communicate with an STM32F407 minimum system through a USB bus, reading four file formats including WAV, MP3, FLAC and APE by using a FATFS file management system, and obtaining audio data in a PCM format after passing through a corresponding digital decoder.
2.2) inputting to the SD card, enabling the SD card module to communicate with the STM32F407 minimum system through SDIO, reading four file formats including WAV, MP3, FLAC and APE by using a FATFS file management system, and obtaining audio data in a PCM format after passing through a corresponding digital decoder.
2.3) inputting an analog audio signal, and after the audio signal is primarily amplified and biased by the audio analog signal amplification module, the audio signal can be maximally sampled by a singlechip ADC of a STM32F407 minimum system, and then multiplied by a corresponding proportionality coefficient to form audio data in a PCM format.
And 2.4) inputting audio Bluetooth, obtaining input data of the audio Bluetooth module by the singlechip through IIS communication, and storing the data into a memory to obtain a PCM audio data format.
And thirdly, loading the PCM audio data obtained in the second step in a timer of an STM32F407 minimum system. Initializing a timer, and setting the frequency, the channel, the dead time and the output polarity of output PWM; and transmitting the audio data processed in the second step to a timer, and outputting PWM to the half-bridge driving module. And transmitting the PCM audio data to two channels of the timer, wherein the two channels respectively correspond to the audio of the left channel and the audio of the right channel, and each timer channel outputs signals to the two half-bridge driving modules.
And fourthly, driving one full-bridge power amplification part by every two half-bridge driving modules. The full-bridge power amplification part comprises four half-bridges, and each two half-bridges form a full-bridge, namely the full-bridge power amplification part comprises two full-bridges, and the output of the two full-bridges is the power amplification of the left and right channels. And each two half-bridge driving modules drive one full bridge in the full-bridge power amplification part through the gate driving resistor and the diodes connected in parallel, and finally, the power amplification of small signals is realized.
And fifthly, filtering the output of the full-bridge power amplification part.
The high-frequency carrier wave and the low-frequency modulation signal output by the full-bridge power amplification part are respectively input into a diaphragm loudspeaker and a plasma loudspeaker:
when the high-frequency carrier and the low-frequency modulation signal output by the full-bridge power amplification part are connected to the diaphragm loudspeaker, a low-pass filter is needed to filter the high-frequency carrier and the low-frequency modulation signal so as to enhance the efficiency and finally realize the playing of audio;
when the output high-frequency carrier wave and the low-frequency modulation signal of the full-bridge power amplification part are connected into the plasma loudspeaker, the high-pass filter is needed to filter the output high-frequency carrier wave and the low-frequency modulation signal, so that the low-frequency power consumption can be reduced, and air is broken down to generate plasma to realize the function of the plasma loudspeaker.
And sixthly, adopting an INA282 current sampling module to sample the current of the output passing through the low-pass filter in the fifth step, and feeding back the current to the STM32F407 minimum system. Specifically, the method comprises the following steps: and an INA282 current sampling module is adopted to sample the current of the output subjected to low-pass filtering by the low-pass filter, and the output is fed back to a single-chip microcomputer ADC of the STM32F407 minimum system, so that an output feedback signal is finally obtained.
And seventhly, setting the IIR digital filter according to the feedback signal output in the sixth step, and accordingly filtering the PCM audio data generated in the first step.
7.1) carrying out Fourier transform on the PCM audio data generated in the first step to finally obtain the amplitude-frequency characteristic of the input signal. The amplitude-frequency characteristic can display a music frequency spectrum through the LCD touch display module.
7.2) carrying out Fourier transform on the output feedback signal of the sixth step to obtain the amplitude-frequency characteristic of the output signal.
7.3) comparing the output feedback signal after Fourier transform with the amplitude of the PCM audio data generated in the first step on each frequency to obtain the transfer function of the low-pass filter.
7.4) determining the parameters of the IIR digital filter according to the transfer function of the low-pass filter.
7.5) processing the audio data in the 16-bit PCM format obtained in the first step by adopting an IIR digital filter to obtain corrected audio data, and enabling the amplitude-frequency characteristic of the audio data after passing through a low-pass filter to be flatter, namely enhancing the high-pitch part.
And eighthly, repeating the third step to the seventh step to realize negative feedback control of output.
The invention has the beneficial effects that:
(1) and frequency domain negative feedback is added, so that the amplitude-frequency characteristic is flat, and the requirement on a filter is reduced.
(2) The discrete device is used, so that the power tube works independently, the efficiency is higher, and the power is greatly improved.
(3) The singlechip is adopted for direct control, no noise exists at the moment of electrifying, and the signal processing capability is stronger.
(4) The distortion is smaller in a high-power occasion, and the total harmonic distortion is within 1% under the power of 100W.
(5) The input mode is various, and the application occasion is more extensive.
(6) The device has strong man-machine interaction, is provided with a touch screen and a Chinese character font library, and can also read and write a U disk and an SD card.
(7) The full-bridge topology is used, the power is supplied by a single power supply, and the power utilization rate is high.
Drawings
FIG. 1 is a schematic diagram of a system for implementing the method of the present invention.
Detailed Description
The present invention is further illustrated by the following specific examples.
The utility model provides a realization method based on high-power low distortion D class power amplifier of high performance MCU, the realization method realize based on system module, wherein, system module includes STM32F407 minimum system, supplementary power supply of step-down, audio frequency bluetooth module, SD card module, USB flash disk module, half-bridge drive module, MOSFET full-bridge power amplification portion, LCD display module, audio frequency analog signal amplification module, word bank storage module, supplementary power supply system of step-down, current sampling module, IIR digital filter, vibrating diaphragm speaker and plasma loudspeaker. The audio Bluetooth module is connected with the STM32F407 minimum system through an I2S communication protocol, the SD card module is connected with the STM32F407 minimum system through SDIO, the U disk module is connected with the STM32F407 minimum system through a USB bus, and the audio analog signal amplification module is connected with the STM32F407 minimum system through an ADC. The half-bridge driving module is connected with the STM32F407 minimum system. The full-bridge power amplification part inputs a driving signal through a half-bridge driving module, the full-bridge power amplification part is connected with an INA282 current sampling module after passing through a low-pass filter, the current sampling module is connected with a diaphragm loudspeaker, and meanwhile, the current sampling module is communicated with an STM32F407 minimum system through an IIR digital filter; the full-bridge power amplification part is also connected with the plasma loudspeaker through a high-pass filter. The word stock storage module is connected with the STM32F407 minimum system through the SPI. The voltage-reducing auxiliary power supply system comprises a 3.3V voltage-reducing auxiliary power supply system, a 5V voltage-reducing auxiliary power supply system and a 2V voltage-reducing auxiliary power supply system, wherein the 3.3V voltage-reducing auxiliary power supply system outputs 3.3V for supplying power to an STM32F407 minimum system, an SD card module, an LCD touch display module, a word stock storage module, an audio analog signal amplification module and an INA282 current sampling module; the 5V voltage reduction auxiliary power supply system outputs 5V to supply power for the voltage reduction auxiliary power supply module, the USB flash disk module, the audio Bluetooth module and the half-bridge driving module; the 12V voltage reduction auxiliary power supply system outputs 12V power for the voltage reduction auxiliary power supply system and the half-bridge driving module. The implementation method specifically comprises the following steps:
first, the selection and display of the play mode.
Firstly, an input signal mode is selected and displayed through an LCD touch display module. The input signal mode comprises U disk input, SD card input, analog audio signal input and audio Bluetooth input. The Chinese character display is realized by communicating a character library storage module with an STM32F407 minimum system, acquiring a character library and displaying the character library on an LCD touch display module.
And secondly, preprocessing the input signal.
2.1) inputting to a USB flash disk, enabling a USB flash disk module to communicate with an STM32F407 minimum system through a USB bus, reading four file formats including WAV, MP3, FLAC and APE by using a FATFS file management system, and obtaining audio data in a PCM format after passing through a corresponding digital decoder.
2.2) inputting to the SD card, enabling the SD card module to communicate with the STM32F407 minimum system through SDIO, reading four file formats including WAV, MP3, FLAC and APE by using a FATFS file management system, and obtaining audio data in a PCM format after passing through a corresponding digital decoder.
2.3) inputting an analog audio signal, and after the audio signal is primarily amplified and biased by the audio analog signal amplification module, the audio signal can be maximally sampled by a singlechip ADC of a STM32F407 minimum system, and then multiplied by a corresponding proportionality coefficient to form audio data in a 16-bit PCM format.
And 2.4) inputting audio Bluetooth, and the singlechip acquires input data of the audio Bluetooth module through IIS communication, stores the data into a memory and acquires a 16-bit PCM audio data format.
Third, 16-bit PCM audio data is loaded in a timer of an STM32F407 minimum system. Initializing a timer, and setting the frequency, the channel, the dead time and the output polarity of output PWM; and transmitting the audio data processed in the second step to a timer to output PWM to the half-bridge driving module. And sending the 16-bit PCM to two channels of a timer, wherein the two channels respectively correspond to the audio of the left channel and the audio of the right channel, and each timer channel outputs signals to two half-bridge driving modules.
And fourthly, driving one full-bridge power amplification part by every two half-bridge driving modules. The full-bridge power amplification part comprises four half-bridges, and each two half-bridges form a full-bridge, namely the full-bridge power amplification part comprises two full-bridges, and the output of the two full-bridges is the power amplification of the left and right channels. And each two half-bridge driving modules drive one full bridge in the full-bridge power amplification part through the gate driving resistor and the diodes connected in parallel, and finally, the power amplification of small signals is realized.
And fifthly, filtering the output of the full-bridge power amplification part.
The high-frequency carrier wave and the low-frequency modulation signal output by the full-bridge power amplification part are respectively input into a diaphragm loudspeaker and a plasma loudspeaker:
when the high-frequency carrier and the low-frequency modulation signal output by the full-bridge power amplification part are connected to the diaphragm loudspeaker, a low-pass filter is needed to filter the high-frequency carrier and the low-frequency modulation signal so as to enhance the efficiency and finally realize the playing of audio;
when the output high-frequency carrier wave and the low-frequency modulation signal of the full-bridge power amplification part are connected into the plasma loudspeaker, the high-pass filter is needed to filter the output high-frequency carrier wave and the low-frequency modulation signal, so that the low-frequency power consumption can be reduced, and air is broken down to generate plasma to realize the function of the plasma loudspeaker.
And sixthly, performing current sampling on the output subjected to low-pass filtering by using an INA282 current sampling module, outputting the current to be fed back to a single-chip microcomputer ADC of the STM32F407 minimum system, and finally obtaining an output feedback signal.
And seventhly, setting the IIR digital filter according to the feedback signal output in the sixth step, and accordingly filtering the PCM audio data generated in the first step.
7.1) carrying out Fourier transform on the PCM audio data generated in the first step to finally obtain the amplitude-frequency characteristic of the input signal. The amplitude-frequency characteristic can display a music frequency spectrum through the LCD touch display module.
7.2) carrying out Fourier transform on the output feedback signal of the sixth step to obtain the amplitude-frequency characteristic of the output signal.
7.3) comparing the output feedback signal after Fourier transform with the amplitude of the PCM audio data generated in the first step on each frequency to obtain the transfer function of the low-pass filter.
7.4) determining the parameters of the IIR digital filter according to the transfer function of the low-pass filter.
7.5) processing the audio data in the 16-bit PCM format obtained in the first step by adopting an IIR digital filter to obtain corrected audio data, and enabling the amplitude-frequency characteristic of the audio data after passing through a low-pass filter to be flatter, namely enhancing the high-pitch part.
And eighthly, repeating the third step to the seventh step to realize negative feedback control of output.
The above-mentioned embodiments only express the embodiments of the present invention, but not should be understood as the limitation of the scope of the invention patent, it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the concept of the present invention, and these all fall into the protection scope of the present invention.
Claims (2)
1. A realization method of a high-power low-distortion D-type power amplifier based on a high-performance MCU is characterized in that the realization method is realized based on a system module, wherein the system module comprises an STM32F407 minimum system, a voltage reduction auxiliary power supply system, an audio Bluetooth module, an SD card module, a USB flash disk module, a half-bridge driving module, an MOSFET full-bridge power amplification part, an LCD display module, an audio analog signal amplification module, a word stock storage module, a current sampling module, an IIR digital filter, a diaphragm loudspeaker and a plasma loudspeaker; the audio Bluetooth module is connected with the STM32F407 minimum system through an I2S communication protocol, the SD card module is connected with the STM32F407 minimum system through SDIO, the USB flash disk module is connected with the STM32F407 minimum system through a USB bus, and the audio analog signal amplification module is connected with the STM32F407 minimum system through an ADC; the half-bridge driving module is connected with the STM32F407 minimum system; the full-bridge power amplification part inputs a driving signal through a half-bridge driving module, the full-bridge power amplification part is connected with an INA282 current sampling module after passing through a low-pass filter, the current sampling module is connected with a diaphragm loudspeaker, and meanwhile, the current sampling module is communicated with an STM32F407 minimum system through an IIR digital filter; the full-bridge power amplification part is also connected with the plasma loudspeaker through a high-pass filter; the word stock storage module is connected with the STM32F407 minimum system through the SPI; the voltage reduction auxiliary power supply system supplies power to the whole system; the method comprises the following steps:
firstly, selecting and displaying a play mode;
selecting and displaying an input signal mode through an LCD touch display module;
secondly, preprocessing an input signal to obtain audio data;
thirdly, loading the PCM audio data obtained in the second step into a timer of an STM32F407 minimum system; initializing a timer, and setting the frequency, the channel, the dead time and the output polarity of output PWM; transmitting the audio data processed in the second step to a timer, and outputting PWM to a half-bridge driving module; transmitting PCM audio data to two channels of a timer, wherein the two channels respectively correspond to audio of a left channel and an audio of a right channel, and each timer channel outputs signals to two half-bridge driving modules;
fourthly, driving a full-bridge power amplification part by every two half-bridge driving modules; the full-bridge power amplification part comprises two full bridges, and the output of the two full bridges is the power amplification of the left and right sound channels; each two half-bridge driving modules drive a resistor and a diode connected in parallel to drive one full bridge in the full-bridge power amplification part, so that power amplification of small signals is realized;
fifthly, filtering the output of the full-bridge power amplification part;
the high-frequency carrier wave and the low-frequency modulation signal output by the full-bridge power amplification part are respectively input into a diaphragm loudspeaker and a plasma loudspeaker:
when the high-frequency carrier and the low-frequency modulation signal output by the full-bridge power amplification part are connected to the diaphragm loudspeaker, a low-pass filter is needed to filter the high-frequency carrier and the low-frequency modulation signal;
when the output high-frequency carrier and low-frequency modulation signals of the full-bridge power amplification part are connected into the plasma loudspeaker, a high-pass filter is needed for filtering the signals;
sixthly, an INA282 current sampling module is adopted to sample the current of the output of the low-pass filter in the fifth step and feed the current back to the STM32F407 minimum system;
seventhly, setting an IIR digital filter according to the feedback signal output in the sixth step, and filtering the PCM audio data generated in the first step;
7.1) carrying out Fourier transform on the PCM audio data generated in the first step to obtain the amplitude-frequency characteristic of the input signal; the amplitude-frequency characteristic can display a music frequency spectrum through the LCD touch display module;
7.2) carrying out Fourier transform on the output feedback signal of the sixth step to obtain the amplitude-frequency characteristic of the output signal;
7.3) comparing the output feedback signal after Fourier transform with the amplitude of the PCM audio data generated in the first step on each frequency to obtain a transfer function of the low-pass filter;
7.4) determining parameters of the IIR digital filter according to the transfer function of the low-pass filter;
7.5) processing the audio data in the 16-bit PCM format obtained in the first step by adopting an IIR digital filter to obtain corrected audio data, so that the amplitude-frequency characteristic of the audio data after passing through a low-pass filter is flatter, namely the high-pitch part is enhanced;
and eighthly, repeating the third step to the seventh step to realize negative feedback control of output.
2. The method according to claim 1, wherein the second step of preprocessing the input signal specifically comprises:
2.1) inputting to the USB flash disk: the U disk module is communicated with the STM32F407 minimum system, a FATFS file management system is used for reading WAV, MP3, FLAC and APE four file formats, and audio data in a PCM format is obtained after the audio data passes through a digital decoder;
2.2) inputting to the SD card: the SD card module is communicated with the STM32F407 minimum system through SDIO, a FATFS file management system is used for reading WAV, MP3, FLAC and APE four file formats, and audio data in a PCM format is obtained after the audio data passes through a digital decoder;
2.3) inputting an analog audio signal: the audio analog signal amplification module performs primary amplification and biasing on an audio signal to form audio data in a PCM format;
2.4) for audio Bluetooth input: the single chip microcomputer obtains input data of the audio Bluetooth module through IIS communication, stores the data into the memory, and obtains a PCM audio data format.
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| CN113162560B (en) | 2023-12-22 |
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