CN114499136A - Method for inhibiting output power frequency ripple of switching power supply - Google Patents
Method for inhibiting output power frequency ripple of switching power supply Download PDFInfo
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- CN114499136A CN114499136A CN202210327871.9A CN202210327871A CN114499136A CN 114499136 A CN114499136 A CN 114499136A CN 202210327871 A CN202210327871 A CN 202210327871A CN 114499136 A CN114499136 A CN 114499136A
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- 238000005070 sampling Methods 0.000 claims abstract description 6
- 230000000452 restraining effect Effects 0.000 abstract description 5
- 230000001629 suppression Effects 0.000 abstract description 3
- 239000003990 capacitor Substances 0.000 description 6
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/14—Arrangements for reducing ripples from dc input or output
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
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Abstract
The invention discloses a method for restraining output power frequency ripple waves of a switching power supply, which comprises an output power frequency ripple wave compensator and an output voltage compensator, wherein the output power frequency ripple wave compensator generates power frequency ripple wave compensation voltage by sampling zero crossing point signals of output current and alternating current input voltage of the switching power supply; summing the power frequency ripple compensation voltage and the default output voltage of the switching power supply to obtain a given voltage, and inputting the given voltage into an output voltage compensator; in the output voltage compensator, given voltage and direct current output feedback voltage of a switching power supply are summed to obtain voltage deviation, the voltage deviation is sent to the loop compensator for operation, the power conversion circuit driving chip outputs PWM driving signals according to the operation result of the loop compensator and controls the power conversion circuit to carry out power conversion. The invention solves the problem of overlarge output power frequency ripple of the switching power supply by using a software algorithm, the suppression effect can reach more than 90 percent, and the hardware cost and the volume of the power supply do not need to be increased.
Description
Technical Field
The invention relates to a control method of a switching power supply, in particular to a method for restraining output power frequency ripples of the switching power supply.
Background
Digital switching power supply technology develops rapidly in recent years, social requirements of high-performance precision power supplies are more and more, and output ripple is a very critical parameter for the high-performance switching precision power supplies. The ripple voltage is easy to generate harmonic waves on the electric appliance, and the safety of the switching power supply is damaged.
As shown in fig. 1, a switching power supply generally consists of two parts, namely AC-DC and DC-DC, after an AC input voltage passes through a rectifying and filtering circuit, an output DC voltage contains an input power frequency ripple, the frequency of the input power frequency ripple is twice the frequency of an input AC power, and the amplitude of the input power frequency ripple is related to the output power of the power supply and the capacity of an output filter capacitor. After the power frequency ripple wave is attenuated by the DC-DC converter, the power frequency ripple wave appears as an output power frequency ripple wave at the output end of the power supply, and the size of the output power frequency ripple wave is determined by the transformation ratio of the DC-DC converter and the gain of a control system. If the low power frequency ripple output of the switching power supply is to be realized, the suppression measures must be taken for the output power frequency ripple.
The conventional methods for suppressing the ripple mainly include the following 4 methods:
1) and (3) increasing the inductance of an output inductor and the capacity of an output capacitor:
according to the formula of the switching power supply, the current fluctuation in the inductor is in inverse proportion to the inductance value, and the output ripple is in inverse proportion to the output capacitance value, so that the output ripple can be reduced by increasing the inductance resistance of the output inductor and the capacity of the output capacitor; because of volume limitation, the output inductance cannot be very large, and the increase of the output capacitance to a certain degree has no obvious effect on reducing power frequency ripples; the method has no obvious effect on reducing the output power frequency ripple.
2) Secondary filtering:
the second-stage filtering is to add a first-stage LC filter at the output end, the LC filter has obvious inhibition effect on ripples, and a filter circuit is formed by selecting proper inductance and capacitance according to the frequency of the ripples to be removed, so that high-frequency ripples can be reduced well. The LC filter is placed after the output voltage sampling point, and because the inductor has a dc resistance, there will be a voltage drop across the inductor, resulting in a decrease in the output voltage of the power supply. The LC filter is placed before the output voltage sampling point, and an inductor and a capacitor are introduced into the power supply system, which easily causes instability of the control system.
3) After the output of the switching power supply, filtering by the linear voltage stabilizer:
the filtering of the linear voltage stabilizer is the most effective method for reducing ripples and noises, the output voltage is constant, the original feedback system is not required to be changed, but the cost is high, the power consumption is large, and the method is not suitable for a high-efficiency switching power supply.
4) Increase Bulk capacitance capacity:
according to the switching power supply formula, the ripple and the capacitance value are in an inverse proportion relation, the input power frequency ripple can be reduced by increasing the capacity of a Bulk capacitor, and then the output power frequency ripple is reduced; however, the method also has the disadvantages of increased capacitance volume, increased cost and unfavorable improvement of the power density of the switching power supply.
The four methods for suppressing the low-frequency ripple waves achieve the purpose of reducing the power-frequency ripple waves by adding additional circuits or increasing the volumes of components, and are not beneficial to improving the power density and reducing the cost of the digital switch power supply.
Disclosure of Invention
The invention aims to provide a method for restraining output power frequency ripples of a switching power supply, which can not reduce power density and improve cost.
In order to solve the technical problems, the invention adopts the technical scheme that the method for inhibiting the output power frequency ripple of the switching power supply comprises an output power frequency ripple compensator and an output voltage compensator, wherein the output power frequency ripple compensator generates power frequency ripple compensation voltage by sampling zero crossing point signals of output current and alternating current input voltage of the switching power supply; summing the power frequency ripple compensation voltage and the default output voltage of the switching power supply to obtain a given voltage, and inputting the given voltage into an output voltage compensator; in the output voltage compensator, given voltage and direct current output feedback voltage of a switching power supply are summed to obtain voltage deviation, the voltage deviation is sent to the loop compensator for operation, the power conversion circuit driving chip outputs PWM driving signals according to the operation result of the loop compensator and controls the power conversion circuit to carry out power conversion.
According to the method, the output power frequency ripple compensator generates power frequency ripple compensation voltage according to the zero-crossing signal of the alternating current input voltage and the output current, the power frequency ripple compensation voltage has the same period with the output power frequency ripple of the switching power supply, the amplitude is equal, and the phase difference is 180 degrees.
In the method, the power frequency ripple compensation voltage is a sine wave.
The method for restraining the output power frequency ripple of the switching power supply solves the problem of overlarge output power frequency ripple of the switching power supply by using a software algorithm, the restraining effect can reach more than 90 percent, and the hardware cost and the size of the power supply do not need to be increased.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 is a circuit block diagram of a prior art switching power supply.
Fig. 2 is a schematic block diagram of a method for suppressing output power-frequency ripple of a switching power supply according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of a zero-crossing signal of an input voltage of a switching power supply according to an embodiment of the invention.
Fig. 4 is a schematic diagram of the compensation of the power frequency ripple at the output of the switching power supply according to the embodiment of the invention.
Detailed Description
The principle of the output power frequency ripple suppression method of the switching power supply of the embodiment of the invention is shown in fig. 2, and the output power frequency ripple compensator generates power frequency ripple compensation voltage according to an alternating current input zero crossing point signal and the output current; the power frequency ripple compensation voltage signal has the same period as the output power frequency ripple signal, the same amplitude and 180-degree phase difference; the result of the addition of the power frequency ripple compensation voltage and the default output voltage is used as a given voltage to enter an output voltage compensator to carry out loop compensation operation, the given voltage contains a power frequency ripple compensation voltage component, the given voltage is added with the feedback voltage, the power frequency ripple compensation voltage component and the power frequency ripple component in the feedback voltage are mutually offset, the power frequency ripple component in the voltage deviation is very small, the driving frequency output after passing through the loop compensator is hardly influenced by the power frequency ripple, and the output power frequency ripple can be greatly reduced.
As shown in fig. 3, an ac input voltage a is full-wave rectified to form a steamed bread wave with twice input frequency, and after power conversion is performed by a transformer, an output voltage contains an output power frequency ripple b with twice input frequency; the output power frequency ripple is the inherent property of the power stage, can only be weakened and cannot be eliminated, and the amplitude of the output power frequency ripple is related to factors such as the power of the switching power supply, the capacity of an electrolytic capacitor and the like.
The digital switch power supply generally adopts negative feedback to control output voltage, the output voltage contains power frequency ripple waves, the output voltage is sampled, and the feedback voltage contains power frequency ripple wave components; the output power frequency ripple compensator of the invention generates a power frequency ripple compensation voltage signal, and the power frequency ripple compensation voltage signal has the same period, equal amplitude and 180-degree phase difference with the output power frequency ripple signal; in the output voltage compensator, the ripple compensation voltage and the power frequency ripple in the output feedback voltage are mutually offset, the power frequency ripple component is weakened before entering the loop compensator, the driving pulse output by the loop compensator is hardly influenced by the power frequency ripple component of the output feedback voltage, the output voltage is more stable through power conversion, and the power frequency ripple in the output voltage is restrained.
When the output power frequency ripple is required to be compensated, firstly, the period of the output power frequency ripple is determined, which is the key for compensating the output power frequency ripple, and the period of a power frequency ripple compensation voltage signal and the period of an output power frequency ripple signal need to be the same, so that the output power frequency ripple can be inhibited; the period of the output power frequency ripple depends on the alternating current input voltage, and as shown by a signal c in fig. 3, the period of the output power frequency ripple can be obtained by detecting the zero crossing point of the alternating current input voltage; in addition, the phase difference between the output power frequency ripple and the ac input voltage is just 180 degrees, as shown by a signal a and a signal b in fig. 3, a zero-crossing point signal of the ac input voltage just corresponds to the trough of the output power frequency ripple, and due to the relationship between the output power frequency ripple and the input voltage, the output ripple compensator generates a power frequency ripple compensation voltage signal having the same period as the output power frequency ripple according to the input voltage zero-crossing point signal.
The amplitude of the output power frequency ripple is in direct proportion to the output power, and under the condition of a certain output voltage, the larger the output current is, the larger the amplitude of the output power frequency ripple is; and detecting the output current, and determining the amplitude of the power frequency ripple compensation voltage by the output power frequency ripple compensator according to the output current sampling signal.
As shown in fig. 4, the period and the amplitude of the ripple compensation voltage are both determined, and there is a relationship that the phase difference between the ac input voltage zero-crossing point signal and the power frequency ripple is 180 °, and according to this relationship, a power frequency ripple compensation signal e having the same period, the same amplitude, and the phase difference of 180 ° as the output power frequency ripple d can be generated, and the power frequency ripple compensation signal e and the output power frequency ripple signal d are added to cancel each other, so that the compensated output power frequency ripple f is very small.
According to the method for inhibiting the output power frequency ripple of the switching power supply, disclosed by the embodiment of the invention, under the condition that the hardware cost and the power supply volume are not increased, the problem of large output power frequency ripple of the digital switching power supply is solved by using a digital switching power supply software algorithm, and the inhibiting effect of the output power frequency ripple can reach more than 90%.
Claims (3)
1. A method for suppressing output power frequency ripple of a switching power supply is characterized by comprising an output power frequency ripple compensator and an output voltage compensator, wherein the output power frequency ripple compensator generates power frequency ripple compensation voltage by sampling zero crossing point signals of output current and alternating current input voltage of the switching power supply; summing the power frequency ripple compensation voltage and the default output voltage of the switching power supply to obtain a given voltage, and inputting the given voltage into an output voltage compensator; in the output voltage compensator, given voltage and direct current output feedback voltage of a switching power supply are summed to obtain voltage deviation, the voltage deviation is sent to the loop compensator for operation, the power conversion circuit driving chip outputs PWM driving signals according to the operation result of the loop compensator and controls the power conversion circuit to carry out power conversion.
2. The method of claim 1, wherein the output power frequency ripple compensator generates a power frequency ripple compensation voltage according to a zero-crossing signal of the ac input voltage and the output current, and the power frequency ripple compensation voltage has a same period, an equal amplitude, and a phase difference of 180 ° with respect to the output power frequency ripple of the switching power supply.
3. The method of claim 1, wherein the power frequency ripple compensation voltage is a sine wave.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210327871.9A CN114499136A (en) | 2022-03-31 | 2022-03-31 | Method for inhibiting output power frequency ripple of switching power supply |
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| CN202210327871.9A CN114499136A (en) | 2022-03-31 | 2022-03-31 | Method for inhibiting output power frequency ripple of switching power supply |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103296871A (en) * | 2013-05-26 | 2013-09-11 | 北京汇能精电科技有限公司 | Ripple modulation compensation method for input voltage of single-phase inverter |
| CN108270348A (en) * | 2018-02-28 | 2018-07-10 | 深圳市鼎硕同邦科技有限公司 | The direct current output low-frequency ripple suppression circuit and its control method of digital charge machine |
| CN207853744U (en) * | 2018-02-28 | 2018-09-11 | 深圳市鼎硕同邦科技有限公司 | Power-supply system with output ripple control in digital charge machine |
| CN108964429A (en) * | 2018-07-12 | 2018-12-07 | 杭州奥能电源设备有限公司 | A kind of switching power unit and its output control method |
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2022
- 2022-03-31 CN CN202210327871.9A patent/CN114499136A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103296871A (en) * | 2013-05-26 | 2013-09-11 | 北京汇能精电科技有限公司 | Ripple modulation compensation method for input voltage of single-phase inverter |
| CN108270348A (en) * | 2018-02-28 | 2018-07-10 | 深圳市鼎硕同邦科技有限公司 | The direct current output low-frequency ripple suppression circuit and its control method of digital charge machine |
| CN207853744U (en) * | 2018-02-28 | 2018-09-11 | 深圳市鼎硕同邦科技有限公司 | Power-supply system with output ripple control in digital charge machine |
| CN108964429A (en) * | 2018-07-12 | 2018-12-07 | 杭州奥能电源设备有限公司 | A kind of switching power unit and its output control method |
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Application publication date: 20220513 |