Flyback switching power supply for reducing peak voltage

Abstract

The invention discloses a flyback switching power supply for reducing peak voltage. The flyback switching power supply comprises a primary signal processing circuit, a primary peak absorption circuit, a primary control circuit, a transformer, at least two secondary winding circuits and a secondary signal output circuit, an output end of the primary side signal processing circuit is connected with a primary winding anode of the transformer, a first end of the primary peak absorption circuit is connected with the primary winding anode of the transformer, and a second end of the primary peak absorption circuit is connected with a primary winding cathode of the transformer and a first control end of the primary control circuit. A second control end of the primary control circuit is connected with a control receiving end of the primary signal processing circuit; the secondary windings of the transformer are connected in series in the corresponding secondary winding circuits, the secondary winding circuits are connected in series and then connected with the input end of the secondary signal output circuit, and the secondary signal output circuit is used for outputting high-voltage signals, so that a switching tube and a diode which bear small peak voltage can be selected at the same time, and the cost of the power supply circuit is reduced.

Description

Technical Field

[0001] The invention relates to the field of flyback switching power supplies, and in particular to a flyback switching power supply for reducing peak voltage. Background Art

[0002] In the flyback switching power supply of the prior art, a diode is serially arranged at the output end of the secondary winding of the transformer, and the primary circuit connected to the primary winding of the transformer is controlled by the primary switch tube. If the power supply needs to output high voltage, the voltage spike is often too high and it is difficult to select or cannot select a suitable rectifier diode or switch tube; for example, the voltage peak Vds of the primary switch tube Q1 is 519V, and the voltage spike Vak of the secondary rectifier diode D3 is 2.521kV. Generally, there are very few types of diodes exceeding 1kV, and the price is relatively high. There are even fewer diodes exceeding 2kV, which is almost equal to none. Or after adjusting the turns ratio of the voltage regulator, the output diode can select a 1kV withstand voltage diode and keep a 10% safety margin, but in this case, the voltage spike of the primary switch tube will reach 753V. In order to ensure a margin of more than 10%, it is necessary to select a 900V withstand voltage switch tube, which is costly. Summary of the invention

[0003] The embodiment of the present invention provides a flyback switching power supply for reducing peak voltage, so as to solve the problem that the existing power supply needs to select a diode or a switch tube that can withstand excessively high voltage spikes, resulting in high cost.

[0004] Based on the above purpose, in one embodiment, a flyback switching power supply for reducing peak voltage is provided, the flyback switching power supply comprising: A primary signal processing circuit (10), a primary peak absorption circuit (20), a primary control circuit (50), a transformer, at least two secondary winding circuits (30), and a secondary signal output circuit (40); wherein the output end of the primary side signal processing circuit is connected to the positive pole of the primary winding of the transformer, the first end of the primary peak absorption circuit (20) is connected to the positive pole of the primary winding of the transformer, the second end of the primary peak absorption circuit (20) is connected to the negative pole of the primary winding of the transformer and the first control end of the primary control circuit (50), and the second control end of the primary control circuit (50) is connected to the control receiving end of the primary signal processing circuit (10); The transformer comprises at least two secondary windings, each of the secondary windings being arranged in series in a corresponding secondary winding circuit (30), each of the secondary winding circuits (30) being connected in series to an input end of a secondary signal output circuit (40), and the secondary signal output circuit (40) being used to output a high voltage signal.

[0005] In one embodiment, the secondary winding circuit (30) comprises a diode and a voltage-stabilizing capacitor, the positive electrode of the diode is connected to one end of the secondary winding, the negative electrode of the diode is connected to the positive electrode of the voltage-stabilizing capacitor, and the negative electrode of the voltage-stabilizing capacitor is connected to the other end of the secondary winding.

[0006] In one embodiment, the primary control circuit (50) is provided with a switch tube for controlling conduction between the primary signal processing circuit (10) and the primary winding of the transformer; The first peak voltage of the switching tube is calculated according to the sum of the maximum DC voltage, the actual reflected voltage and the leakage inductance voltage of the switching tube, and the model of the switching tube is selected according to the first peak voltage; the second peak voltage of the diode is calculated according to the quotient between the maximum DC voltage and the turns ratio of the transformer and then summed with the output voltage, and the model of the diode is selected according to the second peak voltage.

[0007] In one embodiment, the calculation formula of the actual reflected voltage is as follows: in, is the actual reflected voltage, is the output voltage, is the forward voltage drop of the diode, is the actual turns ratio of the transformer, is the theoretical value of reflected voltage, is the maximum duty cycle, is the average DC voltage.

[0008] In one embodiment, the flyback switching power supply further comprises: a voltage stabilizing circuit (60), the voltage stabilizing circuit (60) comprising at least two voltage stabilizing branches, and the number of the voltage stabilizing branches is the same as the number of the secondary winding circuits (30); each of the voltage stabilizing branches is connected in parallel with the voltage stabilizing capacitor in the corresponding secondary winding circuit (30).

[0009] In one embodiment, the voltage stabilizing branch includes at least two resistors, and the resistors are connected in series.

[0010] In one embodiment, two ends of the diode are connected in parallel with a secondary peak absorption circuit, and the secondary peak absorption circuit includes a resistor and a capacitor connected in series.

[0011] In one embodiment, the primary peak absorption circuit (20) comprises: A first resistor (R5), a second resistor (R15), a third resistor (R22), and a first capacitor (C16) connected in series in sequence, one end of the first resistor (R5) being connected to the positive electrode of the primary winding of the transformer, and one end of the first capacitor (C16) being connected to the first control end of the primary control circuit (50); and a fourth resistor (R6) connected in parallel with the first resistor (R5), a fifth resistor (R14) connected in parallel with the second resistor (R15), a sixth resistor (R19) connected in parallel with the third resistor (R22), a first diode (D8) and a second diode (D9) connected in parallel with the first capacitor (C16); and a second capacitor (C5) and a third capacitor (C10) connected in series, one end of the second capacitor (C5) being connected to the positive electrode of the primary winding of the transformer, and one end of the third capacitor (C10) being connected to the sixth resistor (R19).

[0012] In one embodiment, the primary signal processing circuit (10) comprises: An electromagnetic interference suppression circuit comprises: a fuse (F1), a varistor (MOV1), a resistor (RT1), a first common-mode inductor (LF2), a fourth capacitor (CX1), a voltage-stabilizing resistor branch, and a second common-mode inductor (LF1), wherein the input end of the fuse (F1) is used to connect to the positive electrode of a power supply, the output end of the fuse (F1) is connected to the negative electrode of a power supply through the varistor (MOV1), the input end of the resistor (RT1) is connected to the output end of the fuse (F1), the output end of the resistor (RT1) is connected to the input end of the first common-mode inductor (LF2), the output end of the first common-mode inductor (LF2) is respectively connected in parallel with the input ends of the fourth capacitor (CX1) and the voltage-stabilizing resistor branch, the output end of the voltage-stabilizing resistor branch is connected in parallel with the input end of the second common-mode inductor (LF1), and the output end of the second common-mode inductor (LF1) is used to output a first power supply signal; A rectifier and filter circuit comprises: a rectifier bridge module (BD1) and a fifth capacitor (EC1), wherein the input end of the rectifier bridge module (BD1) is connected to the output end of the second common-mode inductor (LF1), the output end of the rectifier bridge module (BD1) is connected to the positive pole of the primary winding of the transformer, and the fifth capacitor (EC1) is connected in parallel to the output end of the rectifier bridge module (BD1).

[0013] In one embodiment, the primary control circuit (50) comprises: A control chip (U3), a switch tube (Q1), and a feedback circuit, wherein the control output end of the control chip (U3) is connected to the control end of the switch tube (Q1) through a seventh resistor (R42) and an eighth resistor (R45), the input end of the switch tube (Q1) is connected to the secondary of the primary winding of the transformer, and the output end of the switch tube (Q1) is connected to the current input end of the control chip (U3) through a ninth resistor (R49); The input end of the feedback circuit is connected to the auxiliary winding of the transformer, the feedback output end of the feedback circuit is connected to the feedback end of the control chip (U3), and the power supply output end of the feedback circuit is connected to the power supply end of the control chip (U3).

[0014] The flyback switching power supply described above uses a plurality of secondary windings of a transformer and a plurality of secondary winding circuits (30) so that each secondary winding is connected in series in a secondary winding circuit (30), and then the output ends of all the secondary winding circuits (30) are connected in series in sequence to output a high-voltage signal through a secondary signal output circuit (40). This structure can reduce the peak voltage that the diode connected in series in the secondary signal output circuit (40) and the switch tube set in the primary control circuit (50) can withstand, so that the switch tube and diode that can withstand a small peak voltage can be selected at the same time, taking into account the selection of the switch tube and the diode, thereby reducing the cost of the power supply circuit to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0016] Figure 1 It is a schematic diagram of a flyback switching power supply for reducing peak voltage in one embodiment of the present invention; Figure 2 It is a schematic diagram of another flyback switching power supply for reducing peak voltage in one embodiment of the present invention.

[0017] The symbols are explained as follows: 10. Primary signal processing circuit; 20. Primary peak absorption circuit; 30. Secondary winding circuit; 40. Secondary signal output circuit; 50. Primary control circuit; 60. Voltage stabilizing circuit; 70. First secondary peak absorption circuit; 71. Second secondary peak absorption circuit. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0020] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0021] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0022] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0023] In order to fully understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0024] In one embodiment, if Figure 1 and Figure 2 As shown, a flyback switching power supply for reducing peak voltage is provided, and the flyback switching power supply comprises: A primary signal processing circuit (10), a primary peak absorption circuit (20), a primary control circuit (50), a transformer, at least two secondary winding circuits (30), and a secondary signal output circuit (40); wherein the output end of the primary side signal processing circuit is connected to the positive pole of the primary winding of the transformer, the first end of the primary peak absorption circuit (20) is connected to the positive pole of the primary winding of the transformer, the second end of the primary peak absorption circuit (20) is connected to the negative pole of the primary winding of the transformer and the first control end of the primary control circuit (50), and the second control end of the primary control circuit (50) is connected to the control receiving end of the primary signal processing circuit (10); The transformer comprises at least two secondary windings, each of the secondary windings being arranged in series in a corresponding secondary winding circuit (30), each of the secondary winding circuits (30) being connected in series to an input end of a secondary signal output circuit (40), and the secondary signal output circuit (40) being used to output a high voltage signal.

[0025] The number of the secondary winding circuits (30) may be two, three, or more than three, and the plurality of secondary winding circuits (30) are sequentially connected in series.

[0026] The secondary signal output circuit (40) comprises: a common-mode inductor LF, a capacitor C8 and a capacitor C15, wherein the positive electrode of the input end of the common-mode inductor LF is connected to the positive electrode of the output end of the first secondary winding circuit (30), and the negative electrode of the input end of the common-mode inductor LF is connected to the ground; and the capacitor C8 and the capacitor C15 are connected in series and then connected in parallel to the output end of the common-mode inductor LF.

[0027] The working process of the above flyback switching power supply is as follows: The power supply outputs a power supply signal to the input end of the primary signal processing circuit (10). The primary signal processing circuit (10) processes the power supply signal and then sends it to the primary winding of the transformer. The primary control circuit (50) sends a conduction signal through the first control end to control the conduction of the loop on the primary winding side of the transformer. The primary peak absorption circuit (20) processes the peak voltage that may be generated by the power supply signal. The primary winding and the secondary winding of the transformer transform the power supply signal on the primary side to each secondary winding circuit (30). Due to the series relationship of each secondary winding circuit (30), a total power supply signal on the secondary side is finally output. After the noise and interference are processed by the secondary signal output circuit (40), the total power supply signal outputs a high-voltage signal.

[0028] The flyback switching power supply of the present embodiment uses a plurality of secondary windings of a transformer and a plurality of secondary winding circuits (30) so that each secondary winding is connected in series in a secondary winding circuit (30). Then, the output ends of all the secondary winding circuits (30) are connected in series in sequence and then output a high-voltage signal through a secondary signal output circuit (40). This structure can reduce the peak voltage that the diode connected in series in the secondary signal output circuit (40) and the switch tube set in the primary control circuit (50) can withstand, so that the switch tube and diode that can withstand a small peak voltage can be selected at the same time, taking into account the selection of the switch tube and the diode, thereby reducing the cost of the power supply circuit to a certain extent.

[0029] In one embodiment, the secondary winding circuit (30) comprises a diode and a voltage-stabilizing capacitor, the positive electrode of the diode is connected to one end of the secondary winding, the negative electrode of the diode is connected to the positive electrode of the voltage-stabilizing capacitor, and the negative electrode of the voltage-stabilizing capacitor is connected to the other end of the secondary winding.

[0030] like Figure 2 As shown, when two secondary winding circuits (30) are provided, the first secondary winding circuit (30) includes a diode D1 and a polarity capacitor EC3 connected in series; the second secondary winding circuit (30) includes a diode D3 and a polarity capacitor EC5 connected in series. The polarity capacitor EC3 is connected in series with the polarity capacitor EC5, so that the output ends of the two secondary winding circuits (30) are connected in series.

[0031] The flyback switching power supply of this embodiment connects the output ends of the two secondary winding circuits (30) in series, so that the peak voltage that the diodes D1 and D3 arranged in series in the secondary signal output circuit (40) and the switch tube Q1 arranged in the primary control circuit (50) can withstand is reduced, so that the switch tube and diode that can withstand a small peak voltage can be selected at the same time, taking into account the selection of the switch tube and the diode, thereby reducing the cost of the power supply circuit to a certain extent.

[0032] In one embodiment, the primary control circuit (50) is provided with a switch tube for controlling conduction between the primary signal processing circuit (10) and the primary winding of the transformer; The first peak voltage of the switching tube is calculated according to the sum of the maximum DC voltage, the actual reflected voltage and the leakage inductance voltage of the switching tube, and the model of the switching tube is selected according to the first peak voltage; the second peak voltage of the diode is calculated according to the quotient between the maximum DC voltage and the turns ratio of the transformer and then summed with the output voltage, and the model of the diode is selected according to the second peak voltage.

[0033] The first peak voltage of the switch tube may be the maximum source-drain voltage of the switch tube, and its expression is as follows: In the formula, is the maximum source-drain voltage of the switch tube, is the maximum DC voltage, is the actual reflected voltage, is the leakage inductance voltage of the switch tube, which is the theoretical value of the reflected voltage Ninety percent.

[0034] The second peak voltage of the diode can be the maximum reverse voltage of the diode, and its expression is as follows: In the formula, is the maximum reverse voltage of the diode, for, is the maximum DC voltage, is the actual turns ratio of the transformer.

[0035] In one embodiment, the calculation formula of the actual reflected voltage is as follows: in, is the actual reflected voltage, is the output voltage, is the forward voltage drop of the diode, is the actual turns ratio of the transformer, is the theoretical value of reflected voltage, is the maximum duty cycle, is the average DC voltage.

[0036] For example, when the actual turns ratio of the transformer is The average DC voltage is 0.545 When it is 117.674V, according to the above calculation formula, it can be calculated that the actual reflected voltage is 109.545V, the maximum source-drain voltage of the switch tube is 561.987V, and the maximum reverse voltage of the diode is 900.62V; therefore, the diode on the secondary circuit can be selected as a 1kV withstand voltage diode with a 10% safety margin, but the voltage spike of the primary switch tube Q1 is 561.9V. In order to ensure a margin of more than 10%, a 650V withstand voltage switch tube can be selected.

[0037] In one embodiment, the flyback switching power supply further comprises: a voltage stabilizing circuit (60), the voltage stabilizing circuit (60) comprising at least two voltage stabilizing branches, and the number of the voltage stabilizing branches is the same as the number of the secondary winding circuits (30); each of the voltage stabilizing branches is connected in parallel with the voltage stabilizing capacitor in the corresponding secondary winding circuit (30).

[0038] like Figure 2 As shown, when two secondary winding circuits (30) are provided, there are two voltage stabilizing branches, wherein the capacitor EC3 in the first secondary winding circuit (30) is connected in parallel with the first voltage stabilizing circuit (60), and the capacitor EC5 in the second secondary winding circuit (30) is connected in parallel with the second voltage stabilizing circuit (60).

[0039] The flyback switching power supply of this embodiment outputs a total power signal with a stable voltage from the series end of each secondary winding circuit (30) by connecting the voltage stabilizing capacitor in parallel with the voltage stabilizing circuit (60) in the corresponding secondary winding circuit (30). After the total power signal is processed by the secondary signal output circuit (40) for noise and interference, a high voltage signal with a stable voltage is output.

[0040] In one embodiment, the voltage stabilizing branch includes at least two resistors, and the resistors are connected in series.

[0041] like Figure 2 As shown, the first voltage stabilizing circuit (60) includes a resistor R4 and a resistor R9 connected in series, and the second voltage stabilizing circuit (60) includes a resistor R16 and a resistor R24 ​​connected in series.

[0042] In one embodiment, two ends of the diode are connected in parallel with a secondary peak absorption circuit, and the secondary peak absorption circuit includes a resistor and a capacitor connected in series.

[0043] like Figure 2 As shown, a series branch of a resistor R1 and a capacitor C1 is connected in parallel at both ends of the diode D1 to form a first secondary peak absorption circuit (70); a series branch of a resistor R17 and a capacitor C13 is connected in parallel at both ends of the diode D3 to form a second secondary peak absorption circuit (71).

[0044] The flyback switching power supply of this embodiment forms an RC absorption loop by arranging a secondary peak absorption circuit at both ends of the diode, so as to further reduce the peak voltage at both ends of the diode.

[0045] In one embodiment, if Figure 2 As shown, the primary peak absorption circuit (20) comprises: A first resistor (R5), a second resistor (R15), a third resistor (R22), and a first capacitor (C16) connected in series in sequence, one end of the first resistor (R5) being connected to the positive electrode of the primary winding of the transformer, and one end of the first capacitor (C16) being connected to the first control end of the primary control circuit (50); and a fourth resistor (R6) connected in parallel with the first resistor (R5), a fifth resistor (R14) connected in parallel with the second resistor (R15), a sixth resistor (R19) connected in parallel with the third resistor (R22), a first diode (D8) and a second diode (D9) connected in parallel with the first capacitor (C16); and a second capacitor (C5) and a third capacitor (C10) connected in series, one end of the second capacitor (C5) being connected to the positive electrode of the primary winding of the transformer, and one end of the third capacitor (C10) being connected to the sixth resistor (R19).

[0046] The flyback switching power supply of this embodiment forms an RCD absorption loop by arranging a primary peak absorption circuit (20) on the primary side of the transformer, so as to further reduce the peak voltage across the switching tube Q1.

[0047] In one embodiment, if Figure 2 As shown, the primary signal processing circuit (10) comprises: An electromagnetic interference suppression circuit comprises: a fuse (F1), a varistor (MOV1), a resistor (RT1), a first common-mode inductor (LF2), a fourth capacitor (CX1), a voltage-stabilizing resistor branch, and a second common-mode inductor (LF1), wherein the input end of the fuse (F1) is used to connect to the positive electrode of a power supply, the output end of the fuse (F1) is connected to the negative electrode of a power supply through the varistor (MOV1), the input end of the resistor (RT1) is connected to the output end of the fuse (F1), the output end of the resistor (RT1) is connected to the input end of the first common-mode inductor (LF2), the output end of the first common-mode inductor (LF2) is respectively connected in parallel with the input ends of the fourth capacitor (CX1) and the voltage-stabilizing resistor branch, the output end of the voltage-stabilizing resistor branch is connected in parallel with the input end of the second common-mode inductor (LF1), and the output end of the second common-mode inductor (LF1) is used to output a first power supply signal; A rectifier and filter circuit comprises: a rectifier bridge module (BD1) and a fifth capacitor (EC1), wherein the input end of the rectifier bridge module (BD1) is connected to the output end of the second common-mode inductor (LF1), the output end of the rectifier bridge module (BD1) is connected to the positive pole of the primary winding of the transformer, and the fifth capacitor (EC1) is connected in parallel to the output end of the rectifier bridge module (BD1).

[0048] The working process of the primary signal processing circuit (10) is as follows: The power source flows to the rectifier filter circuit and the primary control circuit (50) through the electromagnetic interference suppression circuit. The signal flowing to the primary control circuit (50) supplies power to the primary control circuit (50). The rectifier filter circuit rectifies and filters the voltage, converting the alternating current into a direct current to be fed to the transformer.

[0049] The flyback switching power supply of this embodiment prevents the circuit from being subjected to electromagnetic interference by providing an electromagnetic interference suppression circuit, and rectifies and filters the signal by providing a rectifier and filter circuit, thereby ensuring the stability and reliability of the circuit.

[0050] In one embodiment, if Figure 2 As shown, the primary control circuit (50) comprises: A control chip (U3), a switch tube (Q1), and a feedback circuit, wherein the control output end of the control chip (U3) is connected to the control end of the switch tube (Q1) through a seventh resistor (R42) and an eighth resistor (R45), the input end of the switch tube (Q1) is connected to the secondary of the primary winding of the transformer, and the output end of the switch tube (Q1) is connected to the current input end of the control chip (U3) through a ninth resistor (R49); The input end of the feedback circuit is connected to the auxiliary winding of the transformer, the feedback output end of the feedback circuit is connected to the feedback end of the control chip (U3), and the power supply output end of the feedback circuit is connected to the power supply end of the control chip (U3).

[0051] The working process of the primary control circuit (50) is as follows: The feedback circuit feeds back the collected feedback signal to the feedback end of the control chip (U3), and the control chip (U3) timely adjusts the pulse signal of the control switch tube Q1 according to the feedback signal.

[0052] The flyback switching power supply of this embodiment transmits the feedback signal to the control chip by setting a feedback circuit, thereby protecting the control chip. The control chip adjusts the pulse signal in real time according to the feedback signal, thereby ensuring the accuracy of the circuit.

[0053] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A flyback switching power supply for reducing peak voltage, characterized in that: The flyback switching power supply comprises: A primary signal processing circuit (10), a primary peak absorption circuit (20), a primary control circuit (50), a transformer, at least two secondary winding circuits (30), and a secondary signal output circuit (40); wherein the output end of the primary side signal processing circuit is connected to the positive pole of the primary winding of the transformer, the first end of the primary peak absorption circuit (20) is connected to the positive pole of the primary winding of the transformer, the second end of the primary peak absorption circuit (20) is connected to the negative pole of the primary winding of the transformer and the first control end of the primary control circuit (50), and the second control end of the primary control circuit (50) is connected to the control receiving end of the primary signal processing circuit (10); The transformer comprises at least two secondary windings, each of the secondary windings being arranged in series in a corresponding secondary winding circuit (30), each of the secondary winding circuits (30) being connected in series to an input end of a secondary signal output circuit (40), and the secondary signal output circuit (40) being used to output a high voltage signal.

2. The flyback switching power supply according to claim 1, characterized in that: The secondary winding circuit (30) comprises a diode and a voltage-stabilizing capacitor, wherein the positive electrode of the diode is connected to one end of the secondary winding, the negative electrode of the diode is connected to the positive electrode of the voltage-stabilizing capacitor, and the negative electrode of the voltage-stabilizing capacitor is connected to the other end of the secondary winding.

3. The flyback switching power supply according to claim 2, characterized in that: The primary control circuit (50) is provided with a switch tube for controlling conduction between the primary signal processing circuit (10) and the primary winding of the transformer; The first peak voltage of the switching tube is calculated according to the sum of the maximum DC voltage, the actual reflected voltage and the leakage inductance voltage of the switching tube, and the model of the switching tube is selected according to the first peak voltage; the second peak voltage of the diode is calculated according to the quotient between the maximum DC voltage and the turns ratio of the transformer and then summed with the output voltage, and the model of the diode is selected according to the second peak voltage.

4. The flyback switching power supply according to claim 3, characterized in that: The calculation formula of the actual reflected voltage is as follows: in, is the actual reflected voltage, is the output voltage, is the forward voltage drop of the diode, is the actual turns ratio of the transformer, is the theoretical value of reflected voltage, is the maximum duty cycle, is the average DC voltage.

5. The flyback switching power supply according to claim 2, characterized in that: The flyback switching power supply further comprises: a voltage stabilizing circuit (60), the voltage stabilizing circuit (60) comprising at least two voltage stabilizing branches, and the number of the voltage stabilizing branches is the same as the number of the secondary winding circuits (30); each of the voltage stabilizing branches is connected in parallel with the voltage stabilizing capacitor in the corresponding secondary winding circuit (30).

6. The flyback switching power supply according to claim 5, characterized in that: The voltage stabilizing branch includes at least two resistors, and the resistors are connected in series.

7. The flyback switching power supply according to claim 2, characterized in that: A secondary peak absorption circuit is connected in parallel between two ends of the diode, and the secondary peak absorption circuit includes a resistor and a capacitor connected in series.

8. The flyback switching power supply according to claim 1, characterized in that: The primary peak absorption circuit (20) comprises: A first resistor (R5), a second resistor (R15), a third resistor (R22), and a first capacitor (C16) connected in series in sequence, one end of the first resistor (R5) being connected to the positive electrode of the primary winding of the transformer, and one end of the first capacitor (C16) being connected to the first control end of the primary control circuit (50); and a fourth resistor (R6) connected in parallel with the first resistor (R5), a fifth resistor (R14) connected in parallel with the second resistor (R15), a sixth resistor (R19) connected in parallel with the third resistor (R22), a first diode (D8) and a second diode (D9) connected in parallel with the first capacitor (C16); and a second capacitor (C5) and a third capacitor (C10) connected in series, one end of the second capacitor (C5) being connected to the positive electrode of the primary winding of the transformer, and one end of the third capacitor (C10) being connected to the sixth resistor (R19).

9. The flyback switching power supply according to claim 1, characterized in that: The primary signal processing circuit (10) comprises: An electromagnetic interference suppression circuit comprises: a fuse (F1), a varistor (MOV1), a resistor (RT1), a first common-mode inductor (LF2), a fourth capacitor (CX1), a voltage-stabilizing resistor branch, and a second common-mode inductor (LF1), wherein the input end of the fuse (F1) is used to connect to the positive electrode of a power supply, the output end of the fuse (F1) is connected to the negative electrode of a power supply through the varistor (MOV1), the input end of the resistor (RT1) is connected to the output end of the fuse (F1), the output end of the resistor (RT1) is connected to the input end of the first common-mode inductor (LF2), the output end of the first common-mode inductor (LF2) is respectively connected in parallel with the input ends of the fourth capacitor (CX1) and the voltage-stabilizing resistor branch, the output end of the voltage-stabilizing resistor branch is connected in parallel with the input end of the second common-mode inductor (LF1), and the output end of the second common-mode inductor (LF1) is used to output a first power supply signal; A rectifier and filter circuit comprises: a rectifier bridge module (BD1) and a fifth capacitor (EC1), wherein the input end of the rectifier bridge module (BD1) is connected to the output end of the second common-mode inductor (LF1), the output end of the rectifier bridge module (BD1) is connected to the positive pole of the primary winding of the transformer, and the fifth capacitor (EC1) is connected in parallel to the output end of the rectifier bridge module (BD1).

10. The flyback switching power supply according to claim 9, characterized in that: The primary control circuit (50) comprises: A control chip (U3), a switch tube (Q1), and a feedback circuit, wherein the control output end of the control chip (U3) is connected to the control end of the switch tube (Q1) through a seventh resistor (R42) and an eighth resistor (R45), the input end of the switch tube (Q1) is connected to the secondary of the primary winding of the transformer, and the output end of the switch tube (Q1) is connected to the current input end of the control chip (U3) through a ninth resistor (R49); The input end of the feedback circuit is connected to the auxiliary winding of the transformer, the feedback output end of the feedback circuit is connected to the feedback end of the control chip (U3), and the power supply output end of the feedback circuit is connected to the power supply end of the control chip (U3).

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