CN111146952B - Flyback converter - Google Patents

Flyback converter Download PDF

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Publication number
CN111146952B
CN111146952B CN202010073770.4A CN202010073770A CN111146952B CN 111146952 B CN111146952 B CN 111146952B CN 202010073770 A CN202010073770 A CN 202010073770A CN 111146952 B CN111146952 B CN 111146952B
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voltage
unit
circuit
voltage dividing
controller
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CN111146952A (en
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严亮
李鹏
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Msj Systems LLC
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Msj Systems LLC
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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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
    • H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0016—Control circuits providing compensation of output voltage deviations using feedforward of disturbance parameters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The invention relates to a flyback converter comprising: the transformer comprises a primary winding, a secondary winding, a power switch circuit and a voltage input circuit, wherein the power switch circuit and the voltage input circuit are connected with the primary winding, the voltage output circuit is connected with the secondary winding, the secondary winding is coupled with the secondary winding, a controller is connected with the power switch circuit, and a first sampling circuit is connected with a first end of the secondary winding and used for obtaining a first sampling signal corresponding to the first end of the secondary winding; and a second sampling circuit connected to the second end of the auxiliary winding for obtaining a second sampling signal corresponding to the second end of the auxiliary winding; the controller is connected with the first sampling circuit and the second sampling circuit respectively and is used for receiving the first sampling signal and the second sampling signal to acquire the output voltage of the voltage output circuit when the power switch circuit is turned off. The invention has wide application range and can be suitable for various scenes.

Description

Flyback converter
Technical Field
The invention relates to the technical field of power supplies, in particular to a flyback converter.
Background
The loop control of a conventional flyback converter directly detects the output voltage, generates feedback and compensation signals, and determines the duty cycle of the main power switch based on the compensation signals, thereby controlling the output quantity, such as the output voltage. When electrical isolation is required between the input and output of the switching power supply, such as in an off-line converter, the feedback compensation circuit and control circuit are often on either side of the electrically isolated device, i.e., one side is the input side (referred to herein as the "primary side") and the other side is the output side (referred to herein as the "secondary side"). No direct common electrical connection between the primary and secondary sides is made, and isolation devices such as optocouplers are typically used to transfer signals. The isolation devices and their accompanying circuitry add cost and size to the system, often using primary side detection methods in many low cost applications. According to the method, according to the transformer coupling principle, when a primary side main switch is turned off and an output rectifying tube is turned on, a secondary side winding of the transformer bears output voltage, and the voltage on the secondary winding is proportional to the output winding voltage through coupling of the secondary winding and the output winding. The control circuit at the primary side can thus indirectly detect the output voltage value by detecting the voltage on the auxiliary winding.
In addition to providing output voltage detection, the auxiliary winding often provides power to the primary control circuit. Fig. 1 is a schematic diagram of a conventional primary feedback circuit, in which the input voltages Vin, S1 are primary side main switching transistors. The transformer Tx1 has a primary winding Np, a secondary winding Ns, and an auxiliary winding Na. The control circuit outputs a signal DRV to drive S1 on and off. When S1 is on, the transformer accepts stored energy from the input Vin. When S1 turns off, the transformer releases energy to the output. One end of the auxiliary winding is grounded, and the other end supplies power to the control circuit through the rectifying tube. The control circuit is supplied by the auxiliary winding through the rectifier tube D2. The positive terminal of D2 is connected to the positive terminal of the flyback of the auxiliary winding, and the negative terminal of D2 is connected to the control circuit. After the auxiliary winding voltage is divided by resistors R1 and R2, the sampled signal is taken from the junction of R1 and R2. The feedback signal in the feedback sampling method is common to the primary circuit control circuit, so that the detection signal can be obtained by using one control line.
However, the technical scheme is only suitable for the positive end of the rectifier tube which is supplied by the auxiliary circuit and is connected with the flyback of the auxiliary winding. If in application the auxiliary circuit powered rectifier is connected to the negative side of the auxiliary winding when flyback, the sampled signal cannot be obtained by the method described previously. In practical applications, for various reasons, such as for convenience of board arrangement, or changing electromagnetic interference characteristics, when the rectifier needs to be placed at the negative end of the flyback winding, the conventional single detection path cannot obtain a correct detection result of the output voltage.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a flyback converter aiming at the defects of the prior art in the part of the prior art.
The technical scheme adopted for solving the technical problems is as follows: a flyback converter is constructed, comprising: a transformer comprising a primary winding and a secondary winding, a power switching circuit and a voltage input circuit connected to the primary winding, a voltage output circuit connected to the secondary winding, an auxiliary winding coupled to the secondary winding, a controller connected to the power switching circuit, and
the first sampling circuit is connected with the first end of the auxiliary winding and is used for acquiring a first sampling signal corresponding to the first end of the auxiliary winding; and
the second sampling circuit is connected with the second end of the auxiliary winding and is used for acquiring a second sampling signal corresponding to the second end of the auxiliary winding;
the controller is respectively connected with the first sampling circuit and the second sampling circuit and is used for receiving the first sampling signal and the second sampling signal to acquire the output voltage of the voltage output circuit when the power switch circuit is turned off.
Preferably, in the flyback converter of the present invention, the flyback converter further includes a first rectifying unit connected to the auxiliary winding;
the first end of the first rectifying unit is connected with the second end of the auxiliary winding, and the second end of the first rectifying unit is grounded.
In the flyback converter of the present invention, the first rectifying unit includes a rectifying tube D2, an anode of the rectifying tube D2 is grounded, and a cathode of the rectifying tube D2 is connected to the second end of the auxiliary winding.
Preferably, in the flyback converter of the present invention, the first sampling circuit includes a first voltage dividing unit and a second voltage dividing unit;
the first end of the first voltage division unit is connected with the first end of the auxiliary winding, the second end of the first voltage division unit is respectively connected with the controller and the first end of the second voltage division unit, and the second end of the second voltage division unit is connected with the controller and the second end of the auxiliary winding; wherein, the first end of the second voltage division unit is used for outputting the first sampling signal, the second end of the second voltage division unit is used for outputting the second sampling signal, or
The second sampling circuit comprises a third voltage division unit and a fourth voltage division unit;
the first end of the third voltage division unit is connected with the first end of the auxiliary winding, the second end of the third voltage division unit is respectively connected with the controller and the first end of the fourth voltage division unit, the second end of the fourth voltage division unit is connected with the controller and the second end of the auxiliary winding, wherein the first end of the third voltage division unit is used for outputting the first sampling signal, and the second end of the third voltage division unit is used for outputting the second sampling signal.
Preferably, in the flyback converter of the present invention, the first voltage dividing unit includes a voltage dividing resistor R1, a first end of the voltage dividing resistor R1 is connected to a first end of the auxiliary winding, and a second end of the voltage dividing resistor R1 is connected to the controller;
the second voltage dividing unit comprises a voltage dividing resistor R2, a first end of the voltage dividing resistor R2 is connected with a second end of the voltage dividing resistor R1, and a second end of the voltage dividing resistor R2 is connected with a second end of the auxiliary winding; or (b)
The third voltage dividing unit comprises a voltage dividing resistor R11, a first end of the voltage dividing resistor R11 is connected with the first end of the auxiliary winding, and a second end of the voltage dividing resistor R11 is connected with the controller;
the fourth voltage dividing unit comprises a voltage dividing resistor R21, a first end of the voltage dividing resistor R21 is connected with a second end of the voltage dividing resistor R11, and a second end of the voltage dividing resistor R21 is connected with a second end of the auxiliary winding.
Preferably, in the flyback converter of the present invention, the flyback converter further includes a first current limiting unit and/or a second current limiting unit;
a first end of the first current limiting unit is connected with the controller, and a second end of the first current limiting unit is connected with the first sampling circuit;
the first end of the second current limiting unit is connected with the controller, and the second end of the second current limiting unit is connected with the second sampling circuit.
Preferably, in the flyback converter of the present invention, the first current limiting unit includes a current limiting resistor R5, a first end of the current limiting resistor R5 is connected to the controller, and a second end of the current limiting resistor R5 is connected to the first sampling circuit; and/or
The second current limiting unit comprises a current limiting resistor R6, a first end of the current limiting resistor R6 is connected with the controller, and a second end of the current limiting resistor R6 is connected with the second sampling circuit.
Preferably, in the flyback converter of the present invention, the power switch circuit includes a MOS transistor S1, a gate of the MOS transistor S1 is connected to the controller, a source of the MOS transistor S1 is connected to the second end of the primary winding, and a drain of the MOS transistor S1 is grounded.
Preferably, in the flyback converter of the present invention, the voltage input circuit includes a second rectifying unit, a first end of the second rectifying unit is connected to a first end of the primary winding, and a second end of the second rectifying unit is connected to a second end of the primary winding; and/or
The voltage output circuit comprises a third rectifying unit, wherein the first end of the third rectifying unit is connected with the first end of the secondary winding, and the second end of the third rectifying unit is used for outputting the output voltage.
The third rectifying unit comprises a rectifying tube D1, the positive electrode of the rectifying tube D1 is connected with the first end of the secondary winding, and the negative electrode of the rectifying tube D1 is used for outputting the output voltage.
The flyback converter has the following beneficial effects: the method has wide application range and can be suitable for various scenes.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic circuit diagram of a prior art flyback converter;
FIG. 2 is a schematic diagram of a flyback converter according to the present invention;
FIG. 3 is a schematic circuit diagram of an embodiment of a flyback converter according to the present invention;
FIG. 4 is a schematic circuit diagram of another embodiment of a flyback converter according to the present invention;
fig. 5 is a schematic circuit diagram of another embodiment of a flyback converter according to the present invention.
Detailed Description
For a clearer understanding of technical features, objects and effects of the present invention, a detailed description of embodiments of the present invention will be made with reference to the accompanying drawings.
As shown in fig. 2, in a first embodiment of a flyback converter of the present invention, it includes: a transformer comprising a primary winding 210 and a secondary winding 220, a power switching circuit 40 and a voltage input circuit 10 connected to the primary winding 210, a voltage output circuit 30 connected to the secondary winding 220, an auxiliary winding 70 coupled to the secondary winding 220, a controller 50 connected to the power switching circuit 40, and a first sampling circuit 61 connected to a first end of the auxiliary winding 70 for obtaining a first sampling signal corresponding to the first end of the auxiliary winding 70; and a second sampling circuit 62 connected to the second end of the auxiliary winding 70 for obtaining a second sampling signal corresponding to the second end of the auxiliary winding 70; the controller 50 is connected to the first sampling circuit 61 and the second sampling circuit 62, respectively, and is configured to receive the first sampling signal and the second sampling signal to obtain the output voltage of the voltage output circuit 30 when the power switch circuit 40 is turned off. Specifically, the primary winding 210 provides a voltage through the voltage input circuit 10, and controls the voltage output of the voltage output circuit 30 through the power switch circuit 40, and the output of the voltage output circuit 30 supplies power to the controller 50 through the auxiliary winding 70 coupled to the secondary winding 220, so that the controller 50 starts to operate. When the controller 50 starts to operate, that is, when the auxiliary winding 70 couples to the primary winding 210 to generate a voltage, a first sampling signal, which is a sampling signal corresponding to a first end of the auxiliary winding 70, is obtained by the first sampling circuit 61, a second sampling signal, which is a sampling signal corresponding to a second end of the auxiliary winding 70, is obtained by the second sampling circuit 62, and the voltage of the auxiliary winding 70 can be obtained by comparing the sampling signals twice, and further, an output voltage corresponding to the voltage output circuit 30 connected to the secondary winding 220 can be obtained. It can be understood that the voltage parameter corresponding to the first end of the auxiliary winding 70 can be obtained according to the first sampling signal, the voltage parameter corresponding to the second end of the auxiliary winding 70 can be obtained according to the second sampling signal, and the voltage difference between the two ends of the auxiliary winding 70 can be obtained by comparing the two voltage parameters, so as to obtain the corresponding output voltage of the corresponding voltage output circuit 30. The circuit has wide application range and can be suitable for various scenes. Particularly, when the auxiliary winding 70 and the control circuit are not commonly grounded, the control effect of the voltage output can be ensured.
As shown in fig. 3, in one embodiment, a flyback converter according to the present invention further includes a first rectifying unit 80 connected to the auxiliary winding 70; a first end of the first rectifying unit 80 is connected to a second end of the auxiliary winding 70, and a second end of the first rectifying unit 80 is grounded. Specifically, the auxiliary winding 70 is rectified by the first rectifying unit 80 to provide the power supply voltage to the controller 50, wherein the first rectifying unit 80 is connected between the second end of the auxiliary winding 70 and the ground, that is, the second sampling circuit may be connected between the first rectifying unit 80 and the auxiliary winding 70.
As shown in fig. 4, in an embodiment, the first sampling circuit includes a first voltage dividing unit 612 and a second voltage dividing unit 613; a first end of the first voltage dividing unit 612 is connected to a first end of the auxiliary winding 70, a second end of the first voltage dividing unit 612 is connected to the controller 50 and a first end of the second voltage dividing unit 613, and a second end of the second voltage dividing unit 613 is connected to the controller 50 and a second end of the auxiliary winding 70. Specifically, the first sampling signal corresponding to the first end of the auxiliary winding 70 may be implemented by a voltage dividing circuit. Namely, a voltage dividing circuit is formed by the first voltage dividing unit 612 and the second voltage dividing unit 613, a first end of the second voltage dividing unit 613 in the voltage dividing circuit is sampled to obtain a first sampling signal, a second end of the second voltage dividing unit 613 is sampled to obtain a second sampling signal, and according to the first sampling signal and the voltage dividing circuit, the voltage parameter of the first end of the auxiliary winding 70 can be obtained through corresponding calculation.
Further, the first voltage dividing unit 612 includes a voltage dividing resistor R1, a first end of the voltage dividing resistor R1 is connected to a first end of the auxiliary winding 70, and a second end of the voltage dividing resistor R1 is connected to the controller 50; the second voltage dividing unit 613 includes a voltage dividing resistor R2, a first end of the voltage dividing resistor R2 is connected to a second end of the voltage dividing resistor R1, and a second end of the voltage dividing resistor R2 is connected to a second end of the auxiliary winding 70. Specifically, the voltage dividing resistor R1 and the voltage dividing resistor R2 form a voltage dividing circuit, and the first sampling circuit can obtain the voltage parameter of the first end of the auxiliary winding 70 according to the obtained voltage dividing parameter of the voltage dividing resistor R2, namely, the corresponding first sampling signal, and the relationship between the voltage dividing resistor R1 and the voltage dividing resistor R2.
As shown in fig. 5, in an embodiment, the second sampling circuit includes a third voltage dividing unit 622 and a fourth voltage dividing unit 623; the first end of the third voltage division unit 622 is connected to the first end of the auxiliary winding 70, the second end of the third voltage division unit 622 is connected to the first ends of the controller 50 and the fourth voltage division unit 623, and the second end of the fourth voltage division unit 623 is connected to the second ends of the controller 50 and the auxiliary winding 70. Specifically, the second sampling signal corresponding to the second end of the auxiliary winding 70 may be implemented by a voltage dividing circuit. That is, the third voltage dividing unit 622 and the fourth voltage dividing unit 623 form a voltage dividing circuit, the second end of the third voltage dividing unit 622 in the voltage dividing circuit is sampled to obtain a second sampling signal, the first end of the third voltage dividing unit 622 is used for sampling to obtain a first sampling signal, and the voltage parameter of the second end of the auxiliary winding 70 can be obtained through corresponding calculation according to the second sampling signal and the voltage dividing circuit.
Further, the third voltage dividing unit 622 includes a voltage dividing resistor R11, a first end of the voltage dividing resistor R11 is connected to the first end of the auxiliary winding 70, and a second end of the voltage dividing resistor R11 is connected to the controller 50; the fourth voltage dividing unit 623 includes a voltage dividing resistor R21, a first end of the voltage dividing resistor R21 is connected to a second end of the voltage dividing resistor R11, and a second end of the voltage dividing resistor R21 is connected to a second end of the auxiliary winding 70. Specifically, the voltage dividing resistor R11 and the voltage dividing resistor R21 form a voltage dividing circuit, and the second sampling circuit can obtain the voltage parameter of the second end of the auxiliary winding 70 according to the obtained voltage dividing parameter of the voltage dividing resistor R21, namely the corresponding second sampling signal, and the relationship between the voltage dividing resistor R11 and the voltage dividing resistor R21.
In an embodiment, the flyback converter of the present invention further includes a first current limiting unit 611 and/or a second current limiting unit 621; a first end of the first current limiting unit 611 is connected with the controller 50, and a second end of the first current limiting unit 611 is connected with the first sampling circuit; the first end of the second current limiting unit 621 is connected to the controller 50, and the second end of the second current limiting unit 621 is connected to the second sampling circuit. Specifically, since the sampling voltages Va and Vb may have sampling voltages higher than Vcc or lower than GND, in order to avoid a large current generated by an excessive voltage difference, the first sampling signal obtained by the first sampling circuit may be input to the controller 50 for processing after being limited by the first current limiting unit 611. The second sampling signal obtained by the second sampling circuit may be input to the controller 50 for processing after being limited by the second current limiting power supply.
In an example, the first current limiting unit 611 includes a current limiting resistor R5, a first end of the current limiting resistor R5 is connected to the controller 50, and a second end of the current limiting resistor R5 is connected to the first sampling circuit; in another embodiment, the second current limiting unit 621 includes a current limiting resistor R6, a first end of the current limiting resistor R6 is connected to the controller 50, and a second end of the current limiting resistor R6 is connected to the second sampling circuit. Specifically, on the basis of the above, the first current limiting unit 611 and the second current limiting unit 621 may both be current limiting resistors, the first current limiting unit 611 is a current limiting resistor R5, the first sampling signal of the first sampling circuit, that is, the sampling voltage Va, is limited by the current limiting resistor R5, the second current limiting unit 621 is a current limiting resistor R6, and the second sampling signal of the second sampling circuit is limited by the current limiting resistor R6.
In an embodiment, the power switch circuit 40 includes a MOS transistor S1, a gate of the MOS transistor S1 is connected to the controller 50, a source of the MOS transistor S1 is connected to the second end of the primary winding 210, and a drain of the MOS transistor S1 is grounded. Specifically, the voltage output of the primary winding 210 is controlled by the on and off of the MOS transistor S1, that is, when the controller 50 outputs a low level, the MOS transistor S1 is turned off, and at this time, the primary winding 210 outputs energy to the secondary winding 220, and the secondary winding 220 outputs a voltage normally. When the controller 50 outputs a high level, the MOS transistor S1 is turned on, the primary winding 210 does not output energy to the secondary winding 220, and the secondary winding 220 does not generate a voltage output.
In one embodiment, the voltage input circuit 10 includes a second rectifying unit 110, a first end of the second rectifying unit 110 is connected to a first end of the primary winding 210, and a second end of the second rectifying unit 110 is connected to a second end of the primary winding 210; in another embodiment, the voltage output circuit 30 includes a third rectifying unit 310, a first end of the third rectifying unit 310 is connected to a first end of the secondary winding 220, and a second end of the third rectifying unit 310 is used for outputting an output voltage. Specifically, the external input voltage connected to the voltage input circuit 10 is rectified by the second rectifying unit 110 to provide an input voltage to the primary winding 210, and the voltage output circuit 30 connected to the secondary winding 220 rectifies the output of the secondary winding 220 by the third rectifying unit 310 to obtain a preset voltage output.
It is to be understood that the above examples only represent preferred embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the invention; it should be noted that, for a person skilled in the art, the above technical features can be freely combined, and several variations and modifications can be made without departing from the scope of the invention; therefore, all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (8)

1. A flyback converter, comprising: the transformer comprises a primary winding, a secondary winding, a power switch circuit, a voltage input circuit, a voltage output circuit, an auxiliary winding, a controller, a first rectifying unit, a first sampling circuit and a second sampling circuit, wherein the power switch circuit and the voltage input circuit are connected with the primary winding;
the controller is respectively connected with the first sampling circuit and the second sampling circuit and is used for receiving a first sampling signal and a second sampling signal to acquire the output voltage of the voltage output circuit when the power switch circuit is turned off;
the first end of the first rectifying unit is connected with the second end of the auxiliary winding, the second end of the first rectifying unit is grounded, and the auxiliary winding provides power supply voltage for the controller through the first rectifying unit;
the first sampling circuit comprises a first voltage division unit and a second voltage division unit;
the first end of the first voltage division unit is connected with the first end of the auxiliary winding, the second end of the first voltage division unit is respectively connected with the controller and the first end of the second voltage division unit, and the second end of the second voltage division unit is connected with the controller and the second end of the auxiliary winding; wherein, the first end of the second voltage division unit is used for outputting the first sampling signal, the second end of the second voltage division unit is used for outputting the second sampling signal, or
The second sampling circuit comprises a third voltage division unit and a fourth voltage division unit;
the first end of the third voltage division unit is connected with the first end of the auxiliary winding, the second end of the third voltage division unit is respectively connected with the controller and the first end of the fourth voltage division unit, the second end of the fourth voltage division unit is connected with the controller and the second end of the auxiliary winding, the first end of the third voltage division unit is used for outputting the first sampling signal, and the second end of the third voltage division unit is used for outputting the second sampling signal.
2. The flyback converter of claim 1, wherein the first rectifying unit comprises a rectifying tube D2, the positive electrode of the rectifying tube D2 is grounded, and the negative electrode of the rectifying tube D2 is connected to the second end of the auxiliary winding.
3. The flyback converter of claim 1 wherein,
the first voltage dividing unit comprises a voltage dividing resistor R1, a first end of the voltage dividing resistor R1 is connected with a first end of the auxiliary winding, and a second end of the voltage dividing resistor R1 is connected with the controller;
the second voltage dividing unit comprises a voltage dividing resistor R2, a first end of the voltage dividing resistor R2 is connected with a second end of the voltage dividing resistor R1, and a second end of the voltage dividing resistor R2 is connected with a second end of the auxiliary winding; or (b)
The third voltage dividing unit comprises a voltage dividing resistor R11, a first end of the voltage dividing resistor R11 is connected with the first end of the auxiliary winding, and a second end of the voltage dividing resistor R11 is connected with the controller;
the fourth voltage dividing unit comprises a voltage dividing resistor R21, a first end of the voltage dividing resistor R21 is connected with a second end of the voltage dividing resistor R11, and a second end of the voltage dividing resistor R21 is connected with a second end of the auxiliary winding.
4. Flyback converter according to claim 1, further comprising a first current limiting unit and/or a second current limiting unit;
a first end of the first current limiting unit is connected with the controller, and a second end of the first current limiting unit receives the first sampling signal;
the first end of the second current limiting unit is connected with the controller, and the second end of the second current limiting unit receives the second sampling signal.
5. The flyback converter of claim 4,
the first current limiting unit comprises a current limiting resistor R5, a first end of the current limiting resistor R5 is connected with the controller, and a second end of the current limiting resistor R5 receives the first sampling signal; and/or
The second current limiting unit comprises a current limiting resistor R6, a first end of the current limiting resistor R6 is connected with the controller, and a second end of the current limiting resistor R6 receives the second sampling signal.
6. The flyback converter of claim 1 wherein the power switching circuit comprises a MOS transistor S1, a gate of the MOS transistor S1 is connected to the controller, a source of the MOS transistor S1 is connected to the second end of the primary winding, and a drain of the MOS transistor S1 is grounded.
7. The flyback converter of claim 1 wherein,
the voltage input circuit comprises a second rectifying unit, wherein the first end of the second rectifying unit is connected with the first end of the primary winding, and the second end of the second rectifying unit is connected with the second end of the primary winding; and/or
The voltage output circuit comprises a third rectifying unit, wherein the first end of the third rectifying unit is connected with the first end of the secondary winding, and the second end of the third rectifying unit is used for outputting the output voltage.
8. The flyback converter of claim 7 wherein,
the second rectifying unit comprises a resistor Rs, a capacitor Cs and a rectifying tube Ds; after the resistor Rs and the capacitor Cs are connected in parallel, one end of the resistor Rs is connected with the first end of the primary winding, the other end of the resistor Rs is connected with the negative electrode of the rectifying tube Ds, and the positive electrode of the rectifying tube Ds is connected with the second end of the primary winding; and/or
The third rectifying unit comprises a rectifying tube D1, the positive electrode of the rectifying tube D1 is connected with the first end of the secondary winding, and the negative electrode of the rectifying tube D1 is used for outputting the output voltage.
CN202010073770.4A 2020-01-22 2020-01-22 Flyback converter Active CN111146952B (en)

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CN111146952B true CN111146952B (en) 2023-06-30

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102013808A (en) * 2010-12-10 2011-04-13 广东美的电器股份有限公司 Output voltage isolation sampling circuit for DC-DC conversion and control method of output voltage isolation sampling circuit
CN110611431A (en) * 2019-09-30 2019-12-24 东南大学 Primary side regulation control system and control method of active clamp flyback converter
CN211670787U (en) * 2020-01-22 2020-10-13 Msj系统有限责任公司 Flyback converter

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102013808A (en) * 2010-12-10 2011-04-13 广东美的电器股份有限公司 Output voltage isolation sampling circuit for DC-DC conversion and control method of output voltage isolation sampling circuit
CN110611431A (en) * 2019-09-30 2019-12-24 东南大学 Primary side regulation control system and control method of active clamp flyback converter
CN211670787U (en) * 2020-01-22 2020-10-13 Msj系统有限责任公司 Flyback converter

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