Flyback switching power supply

Abstract

The utility model relates to the technical field of switching power supplies, in particular to a flyback switching power supply, which comprises a filter circuit, a rectifying circuit, an inverter circuit and a secondary rectifying circuit, a peak absorption circuit is electrically connected between the inverter circuit and the secondary rectifying circuit, and a feedback circuit is electrically connected between the inverter circuit and the secondary rectifying circuit. The peak absorption circuit comprises an RCD absorption circuit, the RCD absorption circuit is electrically connected with a filtering protection circuit, and the filtering protection circuit comprises a four-operational-amplifier integrated circuit. The RCD absorption circuit not only can consume energy accumulated in leakage inductance of the transformer, but also can consume excitation energy of the transformer, in the design of the RCD absorption circuit, the influence of electromagnetic interference (EMI) needs to be specially paid attention to, the RCD absorption circuit is electrically connected with the filtering protection circuit, and therefore the EMI level can be reduced through the filtering protection circuit.

Description

Technical Field

[0001] The utility model relates to a switching power supply, in particular to a flyback switching power supply, belonging to the technical field of switching power supplies. Background Art

[0002] The flyback switching power supply is a high-efficiency, lightweight and reliable power supply system, which is mainly used to convert AC power into a specific DC voltage or current output to provide the required stable power supply for various electronic devices. The flyback switching power supply means that when the primary coil of the transformer is excited by the DC pulse voltage, the secondary coil of the transformer does not provide power output to the load, but only provides power output to the load after the excitation voltage of the primary coil of the transformer is turned off.

[0003] Working principle: When the switch tube is turned on, the primary inductor current of the transformer begins to rise. At this time, due to the relationship between the secondary same-name terminals, the output diode is cut off and the transformer stores energy; when the switch tube is cut off, the primary inductor induced voltage of the transformer is reversed. At this time, the output diode is turned on, and the energy in the transformer is supplied to the load through the output diode. At the same time, the capacitor is charged to replenish the energy just lost. During the operation of the peak absorption circuit, certain electromagnetic interference will be generated, and the signal quality will be reduced: electromagnetic interference will introduce noise and interference, resulting in a decrease in the signal quality of electronic equipment, which may cause communication interruption, data transmission errors, image and audio distortion and other problems.

[0004] Therefore, there is an urgent need to improve the flyback switching power supply to solve the above-mentioned problems. Utility Model Content

[0005] The purpose of the utility model is to provide a flyback switching power supply. The RCD absorption circuit can not only consume the energy accumulated in the transformer leakage inductance, but also consume the transformer excitation energy. In the design of the RCD absorption circuit, special attention should be paid to the influence of electromagnetic interference EMI. The capacitor C1 and the diode VD1 are arranged in parallel on the diode VDs. The filtering protection circuit is electrically connected to the RCD absorption circuit. Therefore, the electromagnetic interference EMI level can be reduced by the filtering protection circuit.

[0006] In order to achieve the above-mentioned purpose, the main technical solutions adopted by the utility model include:

[0007] A flyback switching power supply comprises an input filter circuit, a rectifier circuit, an inverter circuit and a secondary rectifier circuit, wherein a peak absorption circuit is electrically connected between the inverter circuit and the secondary rectifier circuit, and a feedback circuit is electrically connected between the inverter circuit and the secondary rectifier circuit;

[0008] The peak absorption circuit includes an RCD absorption circuit, the RCD absorption circuit is electrically connected to a filter protection circuit, the RCD absorption circuit includes a capacitor Cs and a resistor Rs arranged in parallel, and a diode VDs is connected after the capacitor Cs and the resistor Rs are connected in parallel;

[0009] The filtering protection circuit includes a four-op-amp integrated circuit, and resistors R2 and R3 are arranged in parallel on pin 11 of the four-op-amp integrated circuit. The resistor R2 is electrically connected to pin 8 of the four-op-amp integrated circuit through capacitor C3, and the resistor R3 is electrically connected to the RCD absorption circuit.

[0010] Preferably, one side of the RCD absorption circuit is electrically connected to an inductor L2 via an inductor L1, a diode VD3 and a diode VD2 are arranged in parallel on one side of the inductor L2, and a capacitor C2 and a resistor R1 are arranged in parallel on the other side of the inductor L2.

[0011] Preferably, a capacitor C1 and a diode VD1 are connected in parallel to the diode VDs.

[0012] Preferably, the inductor L1 is electrically connected to the filter protection circuit through a diode VD4.

[0013] Preferably, a capacitor C4 is electrically connected between the pin 11 of the quad-op-amp integrated circuit and the resistor R2.

[0014] Preferably, the input filter circuit is electrically connected to a rectifier bridge for rectifying the alternating current received at the power input end into direct current.

[0015] Preferably, the inverter circuit is provided with a switch tube, a controller and a transformer, and the transformer is used to step down the high-frequency alternating current.

[0016] Preferably, the feedback circuit is an optocoupler feedback circuit equipped with a voltage regulator tube.

[0017] The utility model has at least the following beneficial effects:

[0018] 1. The RCD absorption circuit can not only consume the energy accumulated in the transformer leakage inductance, but also consume the transformer excitation energy. In the design of the RCD absorption circuit, special attention should be paid to the influence of electromagnetic interference EMI. The capacitor C1 and the diode VD1 are connected in parallel to the diode VDs. The RCD absorption circuit is electrically connected to a filtering protection circuit. Therefore, the electromagnetic interference EMI level can be reduced by the filtering protection circuit.

[0019] 2. The RCD absorption circuit is composed of a resistor Rs, a capacitor Cs and a diode VDs, wherein the resistor Rs is also connected in parallel with the diode VDs. If the switch is disconnected, the energy accumulated in the parasitic inductance will be charged through the parasitic capacitance of the switch. When the switch voltage rises and its voltage rises to the voltage of the absorption capacitor, the absorption diode is turned on, so that the switch voltage is clamped by the absorption diode. At the same time, the energy accumulated in the parasitic inductance also charges the absorption capacitor. When the switch is on, the absorption capacitor is discharged through the resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0021] Figure 1 It is the principle diagram of the utility model;

[0022] Figure 2 This is the RCD absorption circuit diagram of the utility model.

[0023] In the figure, 1. Input filter circuit; 2. Rectification circuit; 3. Inversion circuit; 4. Secondary rectification circuit; 5. Peak absorption circuit; 501. RCD absorption circuit; 502. Filter protection circuit; 6. Feedback circuit. DETAILED DESCRIPTION

[0024] The following will describe the implementation methods of the present application in detail with the help of accompanying drawings and examples, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0025] like Figure 1-Figure 2 As shown, the flyback switching power supply provided in this embodiment includes an input filter circuit 1, a rectifier circuit 2, an inverter circuit 3 and a secondary rectifier circuit 4, a peak absorption circuit 5 is electrically connected between the inverter circuit 3 and the secondary rectifier circuit 4, a feedback circuit 6 is electrically connected between the inverter circuit 3 and the secondary rectifier circuit 4, and the inductor L1 is electrically connected to the filter protection circuit 502 through the diode VD4;

[0026] The input filter circuit 1 is electrically connected to a rectifier bridge, which is used to rectify the AC power received by the power input end into DC power. When the input end of the power supply receives the 220V AC mains power, it passes through the rectifier bridge to rectify the 220V AC into 310V DC.

[0027] The inverter circuit 3 is provided with a switch tube, a controller and a transformer. The transformer is used to reduce the voltage of high-frequency AC power. The core component of the switching power supply is the controller, which controls the power switch tube to convert 310V DC power into high-frequency AC power by repeated switching. The frequency is generally tens of kilohertz to hundreds of kilohertz. The high-frequency AC power can be reduced in voltage after passing through the transformer. Because the frequency of AC power is very high, the volume cost of the transformer can be reduced and the conversion efficiency can be improved. This is why the switching power supply is cheaper than the traditional power frequency transformer.

[0028] Secondary rectifier circuit 4, after high-frequency AC passes through the transformer, the amplitude becomes lower and needs to be converted into DC through a rectifier circuit. The converted DC is the direct output of the power supply;

[0029] Feedback circuit 6 is an optocoupler feedback circuit with a voltage regulator tube. Feedback is the most complex and technically difficult part of the counter-type switching power supply and various other switching power supplies. The function of the optocoupler feedback circuit is that when the voltage at the output end fluctuates or is disturbed to a certain extent, the controller can sense it in time and make appropriate adjustments. The purpose is to quickly stabilize the output voltage. An ideal power supply should quickly return to the target voltage value when facing disturbances, so as to achieve stability, accuracy and speed.

[0030] The peak absorption circuit 5 includes an RCD absorption circuit 501, and a filter protection circuit 502 is electrically connected to the RCD absorption circuit 501. The RCD absorption circuit 501 includes a capacitor Cs and a resistor Rs arranged in parallel, and a diode VDs is connected after the capacitor Cs and the resistor Rs are connected in parallel;

[0031] The RCD absorption circuit 501 is composed of a resistor Rs, a capacitor Cs and a diode VDs, wherein the resistor Rs is also connected in parallel with the diode VDs. If the switch is turned off, the energy stored in the parasitic inductance will be charged through the parasitic capacitance of the switch. When the switch voltage rises and reaches the voltage of the absorption capacitor, the absorption diode is turned on, so that the switch voltage is clamped by the absorption diode. At the same time, the energy stored in the parasitic inductance also charges the absorption capacitor. When the switch is turned on, the absorption capacitor is discharged through the resistor.

[0032] The RCD absorption circuit can also demagnetize the transformer without setting up a demagnetization circuit composed of transformer windings and diodes. The transformer's excitation energy will be consumed in the absorption resistor, which can not only consume the energy accumulated in the transformer leakage inductance, but also consume the transformer's excitation energy;

[0033] In addition, the filtering protection circuit 502 includes a four-op-amp integrated circuit, a resistor R2 and a resistor R3 are arranged in parallel on the pin 11 of the four-op-amp integrated circuit, the resistor R2 is electrically connected to the pin 8 of the four-op-amp integrated circuit through the capacitor C3, the resistor R3 is electrically connected to the RCD absorption circuit 501, one side of the RCD absorption circuit 501 is electrically connected to the inductor L2 through the inductor L1, a diode VD3 and a diode VD2 are arranged in parallel on one side of the inductor L2, a capacitor C2 and a resistor R1 are arranged in parallel on the other side of the inductor L2, and a capacitor C4 is electrically connected between the pin 11 of the four-op-amp integrated circuit and the resistor R2. During the operation of the peak absorption circuit 5, certain electromagnetic interference will be generated, and the signal quality will be reduced: electromagnetic interference will introduce noise and interference, resulting in a reduction in the signal quality of the electronic equipment, which may cause communication interruption, data transmission errors, image and audio distortion and other problems;

[0034] Equipment failure and damage: Strong electromagnetic interference can cause failure and damage to electronic equipment. For example, high-energy electromagnetic pulses (EMP) can overload, burn or damage circuit components, causing the equipment to fail to work properly. In the design of the RCD absorption circuit, special attention should be paid to the influence of electromagnetic interference EMI. The capacitor C1 and the diode VD1 are connected in parallel to the diode VDs. The filter protection circuit 502 is electrically connected to the RCD absorption circuit 501. Therefore, the electromagnetic interference EMI level can be reduced by the filter protection circuit 502.

[0035] like Figure 1-Figure 2 As shown, the principle of the flyback switching power supply provided in this embodiment is as follows: During the operation of the peak absorption circuit 5, certain electromagnetic interference will be generated, and the signal quality will be reduced: electromagnetic interference will introduce noise and interference, resulting in a decrease in the signal quality of the electronic device, which may cause communication interruption, data transmission errors, image and audio distortion and other problems;

[0036] In the design of the RCD absorption circuit, special attention should be paid to the influence of electromagnetic interference EMI. The capacitor C1 and the diode VD1 are connected in parallel to the diode VDs, and the filter protection circuit 502 is electrically connected to the RCD absorption circuit 501. Therefore, the electromagnetic interference EMI level can be reduced by the filter protection circuit 502.

[0037] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0038] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0039] The above description shows and describes several preferred embodiments of the utility model, but as mentioned above, it should be understood that the utility model is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the utility model concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the utility model, and should be within the scope of protection of the claims attached to the utility model.

Claims

1. A flyback switching power supply, comprising an input filter circuit (1), a rectifier circuit (2), an inverter circuit (3) and a secondary rectifier circuit (4), characterized in that: A peak absorption circuit (5) is electrically connected between the inverter circuit (3) and the secondary rectification circuit (4), and a feedback circuit (6) is electrically connected between the inverter circuit (3) and the secondary rectification circuit (4); The peak absorption circuit (5) comprises an RCD absorption circuit (501), the RCD absorption circuit (501) is electrically connected to a filter protection circuit (502), the RCD absorption circuit (501) comprises a capacitor Cs and a resistor Rs arranged in parallel, and a diode VDs is connected after the capacitor Cs and the resistor Rs are connected in parallel; The filtering protection circuit (502) comprises a four-op-amp integrated circuit, a resistor R2 and a resistor R3 are arranged in parallel on a pin 11 of the four-op-amp integrated circuit, the resistor R2 is electrically connected to a pin 8 of the four-op-amp integrated circuit via a capacitor C3, and the resistor R3 is electrically connected to the RCD absorption circuit (501).

2. A flyback switching power supply according to claim 1, characterized in that: One side of the RCD absorption circuit (501) is electrically connected to the inductor L2 via the inductor L1, one side of the inductor L2 is provided with a diode VD3 and a diode VD2 in parallel, and the other side of the inductor L2 is provided with a capacitor C2 and a resistor R1 in parallel.

3. The flyback switching power supply according to claim 1, characterized in that: The diode VDs is connected in parallel with a capacitor C1 and a diode VD1.

4. The flyback switching power supply according to claim 2, characterized in that: The inductor L1 is electrically connected to the filter protection circuit (502) via a diode VD4.

5. The flyback switching power supply according to claim 1, characterized in that: A capacitor C4 is electrically connected between the pin 11 of the quad operational amplifier integrated circuit and the resistor R2 .

6. The flyback switching power supply according to claim 1, characterized in that: The input filter circuit (1) is electrically connected to a rectifier bridge, which is used to rectify the alternating current received at the power input end into direct current.

7. The flyback switching power supply according to claim 1, characterized in that: The inverter circuit (3) is provided with a switch tube, a controller and a transformer, and the transformer is used to reduce the voltage of high-frequency alternating current.

8. The flyback switching power supply according to claim 1, characterized in that: The feedback circuit (6) is an optocoupler feedback circuit equipped with a voltage regulator tube.

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