CN110855139A - Audio power amplification power supply system integrating single-cycle PFC (power factor correction) and frequency conversion technology - Google Patents

Abstract

The present invention is an audio power amplifying power supply system integrating single-cycle PFC and frequency conversion technology, which belongs to the power amplifier switching power supply technology. The AC voltage is converted into a DC voltage through the rectification/filtering circuit; the DC voltage is input into the power factor correction circuit module for power factor correction to improve the power factor and reduce harmonic distortion; Inverting and rectifying filtering, reducing the inrush current when the filter capacitor is charged, and speeding up its charging efficiency; finally input to the large-capacity capacitor to provide energy to the external power amplifier load through the large-capacity capacitor; connect the large-capacity filter capacitor in parallel with the half The output terminal of the bridge inverter circuit makes the output voltage waveform smoother. Thereby, the ripple interference of the power amplifier power supply is reduced, the sound quality and performance of the power amplifier system are guaranteed, and the efficiency of the entire power supply system is improved.

Description

An audio power amplifier power supply system integrating single-cycle PFC and frequency conversion technology

technical field

The invention belongs to the technical field of power amplifier switching power supplies, and in particular relates to an audio power amplification power supply system integrating single-cycle PFC and frequency conversion technology.

Background technique

It is very important to seek a low-cost, small-volume, high-reliability, low-noise DC power supply to ensure the sound quality and performance of Class D power amplifiers. In the past, the power amplifier power supply was mainly realized by the linear power supply. However, the linear regulated power supply has the problems of large size and high cost. Researchers have gradually begun to use switching power supplies to replace linear power supplies, but ordinary switching power supplies have the following problems: (1) The output voltage ripple interference is large, and the harmonic component spectrum is wide, making it difficult to solve the electromagnetic compatibility problem. (2) The energy replenishment speed is low, and the internal resistance after rectification is large; in order to reduce the internal resistance, a power supply system with a capacitor filter of more than 10000 μF should be used. This will make the music still feel less stamina when the music bursts, affecting the transient response.

Therefore, a high-efficiency and stable power conversion technology is needed, which is applied in the development of power amplifier power supplies to reduce the volume of power amplifier power products and greatly eliminate the output ripple voltage, thereby improving the performance and sound quality of class D power amplifiers. At the same time, combined with the power factor correction link, the power factor of the rectifier is improved, and the pollution to the power grid is reduced, so as to adapt to the high-demand workplace.

SUMMARY OF THE INVENTION

Technical problem to be solved:

In order to avoid the shortcomings of the prior art, the present invention proposes an audio power amplification power supply system integrating single-cycle PFC and frequency conversion technology, PFC means power factor correction, (1) through a frequency conversion startup technology, on the one hand, the switching power supply It can stably push the large-capacity filter capacitor to work, and on the other hand, realize the low cost and small size of the power amplifier power supply. (2) The single-cycle power factor correction technology is adopted, on the one hand, it improves the efficiency and reduces the harmonic pollution of the switching power supply system to the power grid, on the other hand, it establishes the closed-loop control of the system and improves the stability of the output voltage.

The technical scheme of the present invention is: an audio power amplifying power supply system integrating single-cycle PFC and frequency conversion technology, which is characterized by comprising: a rectifier/filter circuit, a power factor correction circuit module, a frequency conversion start-up circuit, a large-capacity capacitor and an auxiliary power supply circuit ; Convert the 220V AC voltage to DC voltage through the rectifier/filter circuit; Input the DC voltage into the power factor correction circuit module, perform power factor correction, and reduce the harmonic level of the input current; Then input into the variable frequency start circuit , invert, rectify and filter the DC voltage; finally input it to the large-capacity capacitor, and provide energy to the external power amplifier load through the large-capacity capacitor;

The power factor correction circuit module includes a power factor correction circuit and an OCC control circuit, the power factor correction circuit includes a Boost circuit and an output filter circuit, and the DC voltage output by the rectifier/filter circuit is boosted by the Boost circuit, and then The output filtering is performed once again through the output filtering circuit, and the output terminal of the output filtering circuit outputs a DC voltage; the OCC control circuit includes a PWM generator for outputting a PWM control signal to the power factor correction circuit;

The variable frequency starting circuit includes a half-bridge inverter circuit, an output rectification filter circuit and a variable frequency control circuit, which are used to reduce the inrush current when the large-capacity capacitor is charged; the DC voltage output by the power factor correction circuit is input to the The half-bridge inverter circuit is inverted into a square wave voltage, and then input to the output rectifier and filter circuit; the output rectifier and filter circuit includes a CLC filter circuit and an RC filter circuit, and the input end of the CLC filter circuit is connected to the half-bridge inverter. The output end of the circuit is connected, and the output end is connected with the RC filter circuit; the frequency conversion control circuit is used for outputting the PWM control signal to the half-bridge inverter circuit;

The auxiliary power supply circuit is an AC/DC conversion circuit, and is used for providing voltage to the OCC control circuit and the frequency conversion control circuit.

A further technical solution of the present invention is that: the frequency conversion control circuit includes a control chip, a first power supply circuit and a push-pull circuit, and the push-pull circuit is used to provide a control signal to the MSOFET in the half-bridge inverter circuit; the The first power supply circuit is used to supply voltage to the control chip, and the control chip outputs the generated PWM signal to the push-pull circuit.

A further technical solution of the present invention is: the control chip adopts IR2156.

A further technical solution of the present invention is: the OCC control circuit includes a PFC control chip, a second power supply circuit, a programming circuit, an input current acquisition circuit, an output voltage acquisition circuit, a voltage compensation circuit and an overvoltage acquisition circuit; the PFC control chip Each port of the device is respectively connected with the programming circuit, the input current acquisition circuit, the output voltage acquisition circuit, the voltage compensation circuit and the overvoltage acquisition circuit, and the second power supply circuit is used to provide voltage to the PFC control chip; the OCC The control circuit is used for outputting a PWM signal for controlling the Boost circuit.

A further technical solution of the present invention is: the capacitance value of the large-capacity capacitor is 40,000 μF.

beneficial effect

The beneficial effects of the invention are: in the design of the power amplifier power supply, a large-capacity electrolytic capacitor of 40,000 μF is connected in parallel to the output end of the switching power supply to realize the filtering of the output voltage, and at the same time, the large-capacity capacitive load is stably driven. Single-cycle power factor correction technology reduces the harmonic distortion of the front-end circuit. The frequency conversion start-up technology is based on the half-bridge inverter circuit, adding IR2156 driver chip to drive the switching tube devices, using its high-frequency start-up and low-frequency stable operation functions to reduce the inrush current when the load capacitor is charged, and at the same time Achieve fast charging of load filter capacitors. This technology can solve the problem of large inrush current when a large capacitive load is powered on. The single-cycle power factor correction technology is based on the traditional active power factor correction technology, and realizes the control of the output PWM duty cycle in one cycle, avoiding the complex technology, cumbersome design, large size and large size of the traditional power factor correction circuit. The problem of high cost, while reducing harmonic distortion. By using the two technologies, the ripple of the output voltage can be reduced, the circuit response efficiency can be accelerated, the power factor of the rectifier can be improved, and the pollution to the power grid can be reduced.

The large-capacity filter capacitor is connected in parallel with the output end of the half-bridge inverter circuit to make the output voltage waveform smoother; the frequency conversion starting technology is used to reduce the inrush current when the filter capacitor is charged, and to speed up its charging efficiency; the single-cycle power factor correction is adopted technology to improve power factor and reduce harmonic distortion. Thereby, the ripple interference of the power amplifier power supply is reduced, the sound quality and performance of the power amplifier system are guaranteed, and the efficiency of the entire power supply system is improved.

Description of drawings

Figure 1 is a block diagram of the power amplifier power system design.

Fig. 2 is the circuit diagram that adopts the single-cycle control technique to realize the power factor correction.

Fig. 3 is the circuit diagram of adopting the variable frequency starting technology to promote the charging and working of the load capacitor.

FIG. 4 is an experimental result diagram of the process of establishing the output voltage of the power amplifier switching power supply system of the present invention.

FIG. 5 is a waveform diagram of the power factor correction result of the power amplifier switching power supply system of the present invention.

Detailed ways

The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention and should not be construed as limiting the present invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", " rear, left, right, vertical, horizontal, top, bottom, inside, outside, clockwise, counterclockwise, etc., or The positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as a limitation of the present invention.

Referring to Figures 1 to 3, the present embodiment is a power supply system design technology based on a single-cycle PFC-controlled class-D audio power amplifier, which is characterized by the combination of variable frequency startup technology and single-cycle power factor correction applied to the power amplifier switching power supply In order to improve the power conversion efficiency of this power system and stabilize the output voltage. In this example, the input voltage is AC 220v, the frequency is 50Hz, the output power is 300w, the output DC voltage is 80V, and the output voltage of the PFC stage is 400V. Refer to Figure 2 and Figure 3 for the parameters of the circuit components.

Referring to Fig. 1, a kind of audio power amplifying power supply system integrating single-cycle PFC and frequency conversion technology of the present invention includes a rectifier/filter circuit, a power factor correction circuit module, a frequency conversion start-up circuit, a large-capacity capacitor and an auxiliary power supply circuit; The rectifier/filter circuit is converted into a DC voltage, and then the DC voltage is input into the power factor correction circuit module to perform power factor correction to reduce the harmonic level of the input current; and then input to the variable frequency start circuit to reverse the DC voltage. Transform and rectify and filter; finally input to the large-capacity capacitor, and provide energy to the external power amplifier load through the large-capacity capacitor.

Referring to FIG. 2 , a power factor correction circuit based on a single-cycle control technology is hereinafter referred to as a single-cycle PFC circuit for short. The power factor correction circuit module includes a power factor correction circuit and an OCC control circuit, the power factor correction circuit includes a Boost circuit and an output filter circuit, and the DC voltage output by the rectifier/filter circuit is boosted by the Boost circuit, and then The output filtering is performed once again through the output filtering circuit, and the output terminal of the output filtering circuit outputs a DC voltage; the OCC control circuit includes a PWM generator for outputting a PWM control signal to the power factor correction circuit;

The circuit is mainly divided into two parts, namely the main circuit and the OCC control circuit. The main circuit includes a Boost circuit and an output filter circuit. Boost circuit is composed of inductance L1, switch tube Q1, diode D2 and output capacitor C4, and the closing condition of the switch tube is controlled by the control circuit. The output filter circuit is realized by capacitor E1. In addition to the above sub-modules, there is also a diode in parallel with the Boost circuit in the main circuit. Since the control chip is powered by the voltage divider circuit of the output voltage of the entire power supply system, it is necessary to use this diode to work in the Boost circuit. Before initializing the circuit, power up the control chip. OCC control circuit includes PFC control chip IR1150 and power supply and programming circuit, input current acquisition circuit, output voltage acquisition circuit, voltage compensation circuit and overvoltage acquisition circuit. Refer to the IR1150 data sheet for the specific circuit. The mathematical model of the control circuit mainly includes two loops: the voltage loop and the current loop. The two loops cooperate with each other to control the PWM output duty cycle of the PFC chip to achieve the desired control effect, that is, the waveform of the input current follows Rectified input voltage waveform while maintaining output voltage stability.

Referring to FIG. 3 , the variable frequency start-up circuit includes a half-bridge inverter circuit, an output rectification filter circuit and a variable frequency control circuit, which are used to reduce the inrush current when the large-capacity capacitor is charged; The voltage is input to the half-bridge inverter circuit and is converted into a square wave voltage, and then input to the output rectifier filter circuit; the output rectifier filter circuit includes a CLC filter circuit and an RC filter circuit, and the input end of the CLC filter circuit is connected to the The output end of the half-bridge inverter circuit is connected, and the output end is connected to the RC filter circuit; the frequency conversion control circuit is used for outputting a PWM control signal to the half-bridge inverter circuit.

The frequency conversion control circuit mainly includes a control chip, a first power supply circuit, and a push-pull circuit. The control chip is selected as IR2150, the first power supply circuit provides voltage to the control chip, and the control chip outputs the generated PWM signal to the push-pull circuit; the push-pull circuit is an amplifier circuit composed of four diodes and several resistors , wherein the transistors Q1 and Q3 correspond to the amplifier circuit of the switch Q2, the transistors Q4 and Q6 correspond to the amplifier circuit of the switch Q5, and the drive circuit amplifies the control signal generated by the control chip and the first power supply circuit, and controls the switch device; The bridge inverter circuit is composed of switch tubes Q2 and Q5, capacitors C1 and C6, and a transformer. The inverter circuit receives the control of the control signal, and inverts the DC voltage output by the PFC module; the output rectifier filter circuit converts the inverted The circuit is processed again to make it meet the usage requirements of the load. The working principle of the above drive circuit is as follows: Take the drive circuit of switch Q2 as an example, when the "1" signal is generated by the HO pin of the control chip IR2150, the transistors Q1 and Q3 are turned on, and the current flow at the bias end of the switch Q2 is : +15V→R2→Q1→R3→R5→Q3→VS, at this time, the bias terminal of Q2 has a high voltage, and Q2 is turned on; when the "0" signal generated by the HO pin of the control chip IR2150, the transistors Q1, Q3 are not conducting, the bias terminal of Q2 has no current, and Q2 is not conducting, thus realizing the driving of Q2, that is, the amplification of the output PWM signal of the control chip IR2150. The working principle of the above frequency conversion technology is as follows: in the initial stage of startup, the control chip works in the high-frequency startup mode, and controls the two MOSFETs to be turned on and off at the high-frequency startup frequency. When the time is 660ns, the actual duty cycle is only 36.8% at this time; then, the control chip enters the operating frequency working mode, and controls the two MOSFETs to turn on and off at the normal operating frequency. If the operating frequency is 50kHz, then at this time The actual duty cycle reaches 46.7%. It can be seen that in the initial stage of startup, that is, during high-frequency startup, the voltage applied to the filter capacitor is smaller than the voltage during normal operation, and the inrush current when the capacitor is charged is also reduced. Small. When the high-frequency starting frequency of 200kHz is transitioned to the operating frequency of 50kHz, the charging current of the capacitor will increase, but it will not cause an impact. On the contrary, it can speed up the charging process of the capacitor and make the voltage rapidly rise to a stable working voltage.

The auxiliary power supply circuit is an AC/DC conversion circuit, the input end of which is connected to the rectifier/filter circuit, and the output end of which is connected to the OCC control circuit and the frequency conversion control circuit in turn, and is used to provide the OCC control circuit and the frequency conversion control circuit. low voltage.

In order to confirm whether the design can work stably, effectively and reliably, the experimental verification of the power system is carried out. In the experiment, the operation of the power supply system under the rated load is completed by loading a group of power resistors. The establishment process of the output voltage measured in the experiment is shown in Figure 4. As can be seen from the figure, the output voltage can be quickly established and stable, and there will be two "steps" during the establishment process. The first "step" in the establishment process is due to the low frequency caused by the high-frequency startup proposed above. Voltage start. The second "step" is due to the fact that the front-stage PFC adopts a post-power supply strategy, which leads to a further increase in the voltage after the PFC works. The input current waveform and input voltage waveform measured in the experiment are shown in Figure 5. As can be seen from the figure, the power factor correction circuit can obtain a good control effect.

It can be seen that the power supply system can quickly establish the output voltage, and has the advantages of smaller voltage ripple, stable waveform, smaller inrush current at startup, and stronger reliability than ordinary power supplies. And the single-cycle PFC control technology is used to successfully realize the power factor correction of the input stage.

Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and those of ordinary skill in the art will not depart from the principles and spirit of the present invention Variations, modifications, substitutions, and alterations to the above-described embodiments are possible within the scope of the present invention without departing from the scope of the present invention.

Claims (5)

1. An audio power amplification power supply system integrating a single-cycle PFC and a frequency conversion technology is characterized in that: the power factor correction circuit comprises a rectifying/filtering circuit, a power factor correction circuit module, a variable frequency starting circuit, a large-capacity capacitor and an auxiliary power circuit; converting 220V alternating current voltage into direct current voltage through the rectifying/filtering circuit, inputting the direct current voltage into the power factor correction circuit module, and performing power factor correction to reduce the harmonic level of input current; then inputting the voltage into the frequency conversion starting circuit, inverting the direct current voltage, rectifying and filtering the direct current voltage; finally, the energy is input into the large-capacity capacitor, and the energy is provided for an external power amplifier load through the large-capacity capacitor;

the power factor correction circuit module comprises a power factor correction circuit and an OCC control circuit, the power factor correction circuit comprises a Boost circuit and an output filter circuit, the direct-current voltage output by the rectifying/filtering circuit is boosted by the Boost circuit, then primary output filtering is carried out by the output filter circuit, and the output end of the output filter circuit outputs the direct-current voltage; the OCC control circuit comprises a PWM generator and is used for outputting PWM control signals to the power factor correction circuit;

the variable-frequency starting circuit comprises a half-bridge inverter circuit, an output rectifying filter circuit and a variable-frequency control circuit and is used for reducing the impact current when the high-capacity capacitor is charged; the direct-current voltage output by the power factor correction circuit is input to the half-bridge inverter circuit and is inverted into square wave voltage, and then the square wave voltage is input to the output rectifying and filtering circuit; the output rectifying and filtering circuit comprises a CLC filtering circuit and an RC filtering circuit, wherein the input end of the CLC filtering circuit is connected with the output end of the half-bridge inverter circuit, and the output end of the CLC filtering circuit is connected with the RC filtering circuit; the frequency conversion control circuit is used for outputting a PWM control signal to the half-bridge inverter circuit;

the auxiliary power supply circuit is an AC/DC conversion circuit, the input end of the auxiliary power supply circuit is connected with the rectifying/filtering circuit, and the output end of the auxiliary power supply circuit is sequentially connected with the OCC control circuit and the frequency conversion control circuit and used for supplying voltage to the OCC control circuit and the frequency conversion control circuit.

2. The audio power amplification power supply system of claim 1 that integrates single cycle PFC and frequency conversion techniques, wherein: the frequency conversion control circuit comprises a control chip, a first power supply circuit and a push-pull circuit, wherein the push-pull circuit is used for providing a control signal for MSOFET in the half-bridge inverter circuit; the first power supply circuit is used for providing voltage for the control chip, and the control chip outputs the generated PWM signal to the push-pull circuit.

3. The audio power amplification power supply system of claim 1 that integrates single cycle PFC and frequency conversion techniques, wherein: the control chip adopts IR 2156.

4. The audio power amplification power supply system of claim 1 that integrates single cycle PFC and frequency conversion techniques, wherein: the OCC control circuit comprises a PFC control chip, a second power supply circuit, a programming circuit, an input current acquisition circuit, an output voltage acquisition circuit, a voltage compensation circuit and an overvoltage acquisition circuit; each port of the PFC control chip is respectively connected with the programming circuit, the input current acquisition circuit, the output voltage acquisition circuit, the voltage compensation circuit and the overvoltage acquisition circuit, and the second power supply circuit is used for supplying voltage to the PFC control chip; and the OCC control circuit is used for outputting a PWM signal for controlling the Boost circuit.

5. The audio power amplification power supply system of claim 1 that integrates single cycle PFC and frequency conversion techniques, wherein: the capacitance value of the large-capacity capacitor is 4 ten thousand mu F.

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