CN112737305A - Flyback converter circuit and control method thereof - Google Patents

Flyback converter circuit and control method thereof Download PDF

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Publication number
CN112737305A
CN112737305A CN202110166647.1A CN202110166647A CN112737305A CN 112737305 A CN112737305 A CN 112737305A CN 202110166647 A CN202110166647 A CN 202110166647A CN 112737305 A CN112737305 A CN 112737305A
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winding
turned
switching tube
tube
capacitor
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Inventor
郭春明
李林凯
张程龙
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Huayuan Zhixin Semiconductor Shenzhen Co ltd
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Huayuan Zhixin Semiconductor Shenzhen Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/38—Means for preventing simultaneous conduction of switches
    • 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
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M3/33569—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 having several active switching elements
    • H02M3/33576—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 having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592—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 having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention provides a flyback converter circuit, comprising: the synchronous rectifier comprises a primary winding, a secondary winding, an additional winding module, a charge-discharge module, a main switching tube and a synchronous rectifying tube; the primary winding and the secondary winding are mutually inductive, and the additional winding module and the secondary winding are mutually inductive; the charging and discharging module is connected with the additional winding module; the synchronous rectifier tube is connected between the secondary winding and the ground, and the main switching tube is connected between the primary winding and the ground; the additional winding module is used for: in a first time period, inducing a first voltage of the secondary winding to form a second voltage, and charging the charge and discharge module by using the second voltage; in a second time period, discharging of the charge-discharge module is obtained to form a third voltage, and the third voltage is induced to the secondary winding so as to form a fourth voltage on the secondary winding; the absolute value of the first voltage is higher than the maximum value of the absolute value of the fourth voltage.

Description

Flyback converter circuit and control method thereof
Technical Field
The invention relates to the field of circuits, in particular to a flyback conversion circuit and a control method thereof.
Background
The flyback power supply can also be understood as a flyback transformer switching power supply, and the working principle can be as follows: when the primary winding of the transformer is just excited by the dc pulse voltage, the secondary winding of the transformer does not provide a power output to the load, but only after the excitation voltage of the primary winding of the transformer is turned off.
In the related art, a primary side may be provided with a primary winding and a main switching tube, a secondary side may be provided with a synchronous rectifier, and the synchronous rectifier may change an on-off state based on an actual voltage of the secondary winding and an output voltage output to a load, wherein when the actual voltage is higher than the output voltage, the synchronous rectifier is turned on, and at this time, if a transistor of the primary side is also turned on at the same time, the main switching tube or other transistors (for example, a transistor connected to an auxiliary winding and a power supply winding) of the primary side and the synchronous rectifier are turned on at the same time, and further, a bilateral tube (one or two of the bilateral tubes) may be burned out and failed due to bilateral common connection.
For example: in the actual transformer, leakage inductance exists due to non-ideal coupling, after the main switching tube is turned off, the voltage of the power supply winding or the primary winding is higher than the voltage obtained according to the transformation ratio of each winding and the secondary winding, and the secondary synchronous rectifier tube is turned off and then the primary power supply winding or other windings in the same phase as the secondary winding are turned on, so that the secondary synchronous rectifier tube is possibly conducted again and is in common with the primary and secondary tubes.
Disclosure of Invention
The invention provides a flyback conversion circuit and a control method thereof, which aim to solve the problem that bilateral tubes are likely to be burnt out and fail due to common use.
According to a first aspect of the present invention, there is provided a flyback converter circuit comprising: the synchronous rectifier comprises a primary winding, a secondary winding, an additional winding module, a charge-discharge module, a main switching tube and a synchronous rectifying tube; the primary winding and the secondary winding are mutually inductive, and the additional winding module and the secondary winding are mutually inductive; the charging and discharging module is connected with the additional winding module; the synchronous rectifier tube is connected between the secondary winding and the ground, and the main switching tube is connected between the primary winding and the ground;
the additional winding module is used for:
in a first time period, inducing a first voltage of the secondary winding to form a second voltage, and charging the charge and discharge module by using the second voltage;
in a second time period, discharging of the charge-discharge module is obtained to form a third voltage, and the third voltage is induced to the secondary winding so as to form a fourth voltage on the secondary winding; the first voltage absolute value is higher than the maximum value of the fourth voltage absolute value, and the first time period and the second time period are different time periods;
the charge and discharge module is used for:
receiving the charging of the additional winding module in the first time period, and storing energy;
releasing the stored electrical energy to the additional winding module during the second time period.
Optionally, the charge and discharge module includes a first capacitor, an auxiliary switch tube, and a path guiding unit;
a first end of the first capacitor is directly or indirectly connected to a first end of the additional winding module, a second end of the first capacitor is directly or indirectly connected to a first end of the auxiliary switching tube, and a second end of the auxiliary switching tube is directly or indirectly connected to a second end of the additional winding module; the path guide unit is connected with at least one end of the first capacitor and two ends of the additional winding module;
the auxiliary switch tube is used for:
remain off for the first period of time and remain on for the second period of time;
the path guiding unit is used for:
directing the additional winding module to charge the first capacitor during the first time period;
and guiding the first capacitor to charge the additional winding module in the second time period.
Optionally, the charge-discharge module further includes a second capacitor;
the second end of the first capacitor is connected with the first end of the path guiding unit, the first end of the second capacitor is connected with the second end of the path guiding unit, the second end of the second capacitor is connected with the first end of the auxiliary switching tube, and the path guiding unit is also respectively connected with the first end of the first capacitor and the second end of the second capacitor;
the path guiding unit is specifically configured to:
directing the additional winding module to charge the first capacitor and the second capacitor in series during the first time period;
and in the second time period, the first capacitor is led to be connected with the second capacitor in parallel and then the additional winding module is discharged.
Optionally, the path guiding unit includes a first diode, a second diode, and a third diode;
the positive pole of the first diode is connected with the second end of the first capacitor, the negative pole of the first diode is connected with the first end of the second capacitor, the positive pole of the second diode is connected with the first end of the second capacitor, the negative pole of the second diode is connected with the first end of the first capacitor, the positive pole of the third diode is connected with the second end of the second capacitor, and the negative pole of the third diode is connected with the second end of the first capacitor.
Optionally, the additional winding module comprises an auxiliary winding; the first end of the auxiliary winding is connected to the first end of the first capacitor, and the second end of the auxiliary winding is connected to the second end of the auxiliary switching tube.
Optionally, the flyback converter circuit further includes a power supply energy storage module and a primary side controller for controlling the main switching tube and the auxiliary switching tube, the additional winding module further includes a power supply winding, and the power supply winding and the secondary winding are induced to each other;
the first end of the power supply winding is connected with the power supply energy storage module through a power supply diode, the anode of the power supply diode is connected with the first end of the power supply winding, the first end of the power supply energy storage module is connected with the power supply end of the primary side controller, and the second end of the power supply winding and the second end of the power supply energy storage module are both connected to the ground.
Optionally, the flyback converter circuit further includes a power supply and energy storage module, and a primary side controller for controlling the main switching tube and the auxiliary switching tube;
the first end of the auxiliary winding is connected with the power supply energy storage module through a power supply diode, the anode of the power supply diode is connected with the first end of the auxiliary winding, the first end of the power supply energy storage module is connected with the power supply end of the primary side controller, the second end of the auxiliary winding is connected to the ground through the auxiliary switch tube, and the second end of the power supply energy storage module is connected to the ground.
Optionally, the flyback converter circuit further includes a power supply energy storage module and a primary side controller for controlling the main switching tube and the auxiliary switching tube, and the additional winding module includes an auxiliary winding and a power supply winding; the power supply winding and the secondary winding are mutually inductive, and the auxiliary winding and the secondary winding are mutually inductive;
the first end of the power supply winding is connected with the first end of the first capacitor, the first end of the power supply winding is further connected with the first end of the power supply energy storage module through a power supply diode, the anode of the power supply diode is connected with the first end of the power supply winding, the second end of the power supply winding is connected with the first end of the auxiliary winding, the second end of the auxiliary winding is connected with the second end of the auxiliary switching tube through the path guiding unit, the second end of the first capacitor is connected with the second end of the power supply winding through the path guiding unit, and the second end of the first capacitor is connected with the first end of the auxiliary switching tube; the second end of the first capacitor and the second end of the power supply energy storage module are both connected to the ground;
the path guiding unit is used for:
directing the power supply winding to charge the first capacitor during the first time period;
and in the second time period, the first capacitor is guided to discharge the power supply winding and the auxiliary winding which are connected in series.
Optionally, the path guiding unit includes a fourth diode and a fifth diode;
the anode of the fourth diode is connected between the second end of the first capacitor and the first end of the auxiliary winding, and the cathode of the fourth diode is connected with the first end of the auxiliary winding; the fifth diode is connected between the second end of the auxiliary winding and the second end of the auxiliary switching tube, and the anode of the fifth diode is connected with the second end of the auxiliary winding.
Optionally, the flyback converter circuit further includes a control module, and the control module is connected to the control end of the synchronous rectifier tube;
the control module is used for:
and when the main switching tube is kept to be switched off and the synchronous rectifying tube is kept to be switched on, the synchronous rectifying tube is switched off according to the excitation inductive current corresponding to the primary winding.
Optionally, the control module is further connected to the control end of the main switching tube and the control end of the auxiliary switching tube, respectively;
the control module is specifically configured to:
after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on;
when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and the auxiliary switching tube is turned on.
Optionally, the control module is further connected to the control end of the main switching tube and the control end of the auxiliary switching tube, respectively;
the control module is specifically configured to:
after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on, and the auxiliary switching tube is turned on after delaying for the first time;
when the main switching tube is kept to be turned off, the synchronous rectifying tube is kept to be turned on, and the auxiliary switching tube is kept to be turned on, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifying tube is turned off.
Optionally, the control module is further connected to the control end of the main switching tube and the control end of the auxiliary switching tube, respectively;
the control module is specifically configured to:
after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on;
when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and after the second time, the auxiliary switching tube is turned on.
Optionally, when the flyback converter circuit is in the DCM mode, the second time δ t satisfies the following formula:
Figure RE-GDA0002943825140000051
wherein:
tr characterizes the resonance period in DCM;
n characterizes the number of troughs of resonance in DCM mode.
Optionally, the control module includes a primary side controller for controlling the main switching tube and the charging and discharging module, and a synchronous rectification controller for controlling the synchronous rectification tube.
Optionally, the flyback converter circuit further includes a clamping module connected to two ends of the primary winding.
Optionally, the clamping module includes a clamping resistor, a clamping capacitor, and a clamping diode;
the first end of the clamping resistor connected with the clamping capacitor in parallel is connected with the first end of the primary winding, the second end of the clamping resistor connected with the clamping capacitor in parallel is connected with the second end of the primary winding through the clamping diode, and the anode of the clamping diode is connected with the second end of the primary winding.
According to a second aspect of the present invention, there is provided a control method for a flyback converter circuit according to the first aspect, which is applied to a control module, where the control module is respectively connected to a control end of the auxiliary switching tube, a control end of the synchronous rectifying tube, and a control end of the main switching tube;
the control method comprises the following steps:
and when the main switching tube is kept to be switched off and the synchronous rectifying tube is kept to be switched on, the synchronous rectifying tube is switched off according to the excitation inductive current corresponding to the primary winding.
Optionally, before controlling the synchronous rectifier according to the excitation inductance current corresponding to the primary winding, the method further includes:
and after the synchronous rectifier tube and the auxiliary switching tube are kept off and the main switching tube is turned off, the synchronous rectifier tube is turned on.
Optionally, turning off the synchronous rectifier tube according to the excitation inductance current corresponding to the primary winding specifically includes:
when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and the auxiliary switching tube is turned on.
Optionally, after the synchronous rectifier tube is opened, the method further includes: after delaying the first time, opening the auxiliary switch tube;
according to the excitation inductive current that primary winding corresponds, turn off synchronous rectifier, specifically include:
when the main switching tube is kept to be turned off, the synchronous rectifying tube is kept to be turned on, and the auxiliary switching tube is kept to be turned on, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifying tube is turned off.
Optionally, controlling the synchronous rectifier tube according to the excitation inductance current corresponding to the primary winding specifically includes:
when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and after the second time, the auxiliary switching tube is turned on.
Optionally, when the flyback converter circuit is in the DCM mode, the second time δ t satisfies the following formula:
Figure RE-GDA0002943825140000061
wherein:
tr characterizes the resonance period in DCM;
n characterizes the number of troughs of resonance in DCM mode.
In the flyback conversion circuit and the control method thereof provided by the invention, the second voltage formed by inducing the first voltage of the secondary winding in the additional winding module can be used for charging the charging and discharging module, the third voltage is induced to the secondary winding when discharging, and the smaller fourth voltage is formed on the secondary winding, so that the actual voltage of the secondary winding is smaller (smaller than the output voltage output to a load) at the moment, and further, the synchronous rectifier tube cannot be opened because the voltage of the secondary winding is larger than the output voltage.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a first schematic structural diagram of a flyback converter circuit according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a flyback converter circuit according to an embodiment of the present invention;
fig. 3 is a first schematic circuit diagram of a portion of a flyback converter circuit according to an embodiment of the present invention;
fig. 4 is a partial circuit diagram of a flyback converter circuit according to an embodiment of the present invention;
fig. 5 is a first circuit diagram of a flyback converter circuit according to an embodiment of the present invention;
fig. 6 is a first waveform diagram of a flyback converter circuit according to an embodiment of the present invention;
fig. 7 is a waveform diagram illustrating a flyback converter circuit according to an embodiment of the invention;
fig. 8 is a waveform diagram of a flyback converter circuit according to an embodiment of the present invention;
fig. 9 is a second circuit schematic diagram of the flyback converter circuit according to an embodiment of the present invention;
fig. 10 is a third schematic diagram of a flyback converter circuit according to an embodiment of the present invention;
fig. 11 is a schematic diagram of a partial circuit of a flyback converter circuit according to an embodiment of the invention;
fig. 12 is a schematic diagram of a partial circuit of a flyback converter circuit according to an embodiment of the present invention;
fig. 13 is a second circuit schematic diagram of the flyback converter circuit according to the embodiment of the present invention;
fig. 14 is a first flowchart illustrating a method for controlling a flyback converter circuit according to an embodiment of the present invention;
fig. 15 is a second flowchart illustrating a control method of the flyback converter circuit according to an embodiment of the present invention;
fig. 16 is a third flowchart illustrating a control method of the flyback converter circuit according to an embodiment of the present invention;
fig. 17 is a fourth flowchart illustrating a control method of the flyback converter circuit according to an embodiment of the present invention.
Description of reference numerals:
11-additional winding modules; 12-a charge-discharge module; 121-a path guiding unit; 13-a control module; 131-primary side controller; 132-synchronous rectification controller;
q-main switching tube; qr-synchronous rectifier tube; qaux-auxiliary switching tube; q1-triode;
lp-primary winding; ls-secondary winding; la-auxiliary winding;
c0-power supply energy storage capacitor; c1 — first capacitance; c2 — second capacitance; c-clamp capacitance;
d0-supply diode; d1 — first diode; d2 — second diode; d3 — third diode; d4 — fourth diode; d5-fifth diode; d6-zener diode; d7-light emitting diode; a D-clamp diode;
r-clamp resistor; r1, R2, R3, R4, R5, R6, R7-resistors;
llk1, Llk-leakage inductance;
c3 — output capacitance; c4, C5, C6-capacitance.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims, as well as in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.
Referring to fig. 1, the flyback converter circuit includes: the synchronous rectifier comprises a primary winding Lp, a secondary winding Ls, an additional winding module 11, a charging and discharging module 12, a main switching tube Q and a synchronous rectifier Qr.
The primary winding Lp and the secondary winding Ls mutually induce, which can be understood by referring to the structure, circuit and action principle between the primary winding Lp and the secondary winding Ls in the transformer, and the specific number of turns can be arbitrarily configured according to the requirement.
The additional winding module 11 can be understood as any circuit module having a winding, and can specifically interact with the secondary winding Ls, and further, the auxiliary winding module 11 can induce a voltage from the secondary winding and can also induce electric energy to the secondary winding.
The charge-discharge module 12 is connected to the additional winding module 11, and may be specifically connected to one end, two ends, or three ends of the additional winding module 11.
The synchronous rectifier Qr is connected between the secondary winding Ls and the ground, so as to control the on-off between the secondary winding Ls and the ground. The synchronous rectifier may be any transistor, for example, NMOS, which may have a body diode, and when turned on, the synchronous rectifier Qr may be turned on after the body diode is turned on. Further, the turning on of the synchronous rectifier Qr mentioned later includes a case of directly driving the turning on of the synchronous rectifier Qr and a case of waiting for a certain period of time to turn on the body diode and then driving the turning on of the synchronous rectifier Qr. If an NMOS is adopted, then: the drain of the synchronous rectifier Qr is connected to the secondary winding Ls.
The main switching tube Q is connected between the primary winding Lp and the ground; the synchronous rectifier may adopt any transistor, for example, NMOS, in which the drain of the main switch Q may be connected to the primary winding Lp.
The additional winding module 11 can be understood to be used for:
in a first time period, inducing a first voltage of the secondary winding to form a second voltage, and charging the charge and discharge module by using the second voltage; the first voltage and the second voltage may be the same or different, and the relationship between the first voltage and the second voltage may be variable or unchangeable;
in a second time period, discharging of the charge-discharge module is obtained to form a third voltage, and the third voltage is induced to the secondary winding so as to form a fourth voltage on the secondary winding; the third voltage and the fourth voltage may be the same or different, and the relationship between the third voltage and the fourth voltage may be changed or may not be changed.
The charge-discharge module 12 may be understood to be for:
receiving the charging of the additional winding module in the first time period, and storing energy;
releasing the stored electrical energy to the additional winding module during the second time period.
The first time period and the second time period may be any different time periods, the first time period is a time period in which the charge and discharge module 12 can receive charge, and the second time period is a time period in which the charge and discharge module 12 can discharge the additional winding module.
The first voltage and the fourth voltage may be: the absolute value of the first voltage is higher than the maximum value of the absolute value of the fourth voltage, and therefore the additional winding module can induce a higher voltage from the secondary winding to store the higher voltage, but can utilize a lower voltage to realize the induction to the secondary winding.
For example: assuming that the first voltage is 15v, the second voltage and the first voltage may be in a certain ratio based on the coil, for example, may also be 15v, and accordingly, a third voltage and a fourth voltage smaller than 15v need to be formed. In the following alternatives of the embodiments of the present invention, how to implement the magnitude relationship between the first voltage and the fourth voltage may be specifically described, and those skilled in the art may realize the object by combining the existing or improved schemes without departing from the scope of the embodiments of the present invention after knowing the requirement.
It can be seen that, the scheme for realizing the magnitude relation between the absolute values of the first voltage and the fourth voltage may be any, in the schemes shown in fig. 2 to 5 and 9, the required magnitude relation may be realized by using the serial charging and parallel discharging of the capacitors, and in the scheme shown in fig. 13, the required magnitude relation may be realized by using the coupling of one winding during charging and the coupling of two windings during discharging.
In a not shown embodiment, the above size relationship can also be achieved by using windings with different numbers of coil turns, for example: the charging and discharging module receives charging of one winding during charging, and switches to discharging to another winding during discharging, specifically, a diode may be disposed between a capacitor and one winding in the charging and discharging module, the capacitor, the winding and the diode may form a loop in one direction (the loop may be formed in a first time period), another diode may be disposed between the capacitor and another winding in the charging and discharging module, the capacitor, the winding and the diode may form a loop in another direction (the loop may be formed in a second time period), and meanwhile, an auxiliary switch tube may be disposed in one of the two paths to be matched with a current direction of the winding and to control on and off of the auxiliary switch tube, so that a process of charging and discharging may be achieved, and the number of turns in the winding may also be configured based on requirements of the first voltage and the fourth voltage.
Therefore, in the flyback converter circuit provided in the embodiment of the present invention, no matter how the magnitude relationship between the first voltage and the fourth voltage is implemented, the second voltage induced in the secondary winding by the additional winding module to form the first voltage can be used to charge the charging/discharging module, and the third voltage is used to induce the second voltage to the secondary winding during discharging, so that a smaller fourth voltage is formed in the secondary winding, which ensures that the actual voltage at the secondary winding is smaller (smaller than the output voltage output to the load), and further, the synchronous rectifier tube is not opened because the voltage of the secondary winding is greater than the output voltage.
In one embodiment, referring to fig. 2 to 5 and 9 to 13, the charge/discharge module 12 includes a first capacitor C1, an auxiliary switch Qaux and a path guiding unit 121.
A first end of the first capacitor C1 is directly or indirectly connected to a first end of the additional winding module 11, a second end of the first capacitor C1 is directly or indirectly connected to a first end of the auxiliary switching tube Qaux, and a second end of the auxiliary switching tube Qaux is directly or indirectly connected to a second end of the additional winding module 11; the path guide unit 121 is connected to at least one end of the first capacitor C1 and both ends of the additional winding module 11.
The auxiliary switch tube Qaux is used for: remain off for the first period of time and remain on for the second period of time; meanwhile, the main switch Q and the synchronous rectifier Qr can be controlled according to the required timing sequence.
The auxiliary switching tube Qaux may adopt any transistor, for example, an NMOS, wherein the drain of the main switching tube Q may be connected to the additional winding module 11 (for example, the auxiliary winding La).
The path guiding unit 121 is configured to:
directing the additional winding module to charge the first capacitor during the first time period;
and guiding the first capacitor to charge the additional winding module in the second time period.
The charging and discharging of the additional winding module may be charging and discharging of a part of windings, or charging and discharging of all windings, and the windings for charging and discharging may be the same or different.
The path guiding unit 121, and the connection relationship between the path guiding unit and the capacitor and the additional winding module 11 may be specifically configured according to different implementations of the magnitude relationship between the first voltage and the fourth voltage.
In one embodiment, the magnitude relationship required by the first voltage and the fourth voltage can be realized by using a series charging and parallel discharging manner of the capacitor. Furthermore, the charge-discharge module further comprises a second capacitor C2.
A second terminal of the first capacitor C1 is connected to a first terminal of the path guiding unit 121, a first terminal of the second capacitor C2 is connected to a second terminal of the path guiding unit 121, a second terminal of the second capacitor C2 is connected to a first terminal of the auxiliary switching tube Qaux, and the path guiding unit 121 is further connected to a first terminal of the first capacitor C1 and a second terminal of the second capacitor C2, respectively.
The path guiding unit 121 is specifically configured to:
directing the additional winding module to charge the first capacitor and the second capacitor in series during the first time period;
and in the second time period, the first capacitor is led to be connected with the second capacitor in parallel and then the additional winding module is discharged.
The first capacitor C1 and the second capacitor C2 may be two capacitors with the same capacitance value, or two capacitors with different capacitance values.
The path guiding unit 121 for realizing the above path guiding function may be implemented by a diode, a transistor, or a combination of a transistor and a diode, as long as the formed path can realize parallel discharging and serial charging of two capacitors, the scope of the above solution is not deviated, and the number of capacitors is not limited to the above example. The number of capacitors connected in parallel and in series may be two, or may not be limited to two.
In a further aspect, if the function of the path guiding unit 121 is implemented by a diode, then: referring to fig. 4, the path guiding unit 121 includes a first diode D1, a second diode D2, and a third diode D3.
The anode of the first diode D1 is connected to the second end of the first capacitor C1, the cathode of the first diode D1 is connected to the first end of the second capacitor C2, the anode of the second diode D2 is connected to the first end of the second capacitor C2, the cathode of the second diode D2 is connected to the first end of the first capacitor C1, the anode of the third diode D3 is connected to the second end of the second capacitor C2, and the cathode of the third diode D3 is connected to the second end of the first capacitor C1.
During charging, the first diode D1 is turned on, the second diode D2 and the third diode D3 are both turned off, the two capacitors are connected in series to receive charging, during discharging, the first diode D1 is turned off, the second diode D2 and the third diode D3 are both turned on, and the two capacitors are connected in parallel to discharge.
In one embodiment, please refer to fig. 4, the additional winding module 11 includes an auxiliary winding La; a first end of the auxiliary winding La is connected to a first end of the first capacitor C1 (for example, the first end of the first capacitor C1 may be connected via a leakage inductor Llk1 shown in fig. 5), and accordingly, a voltage VC may be formed at the first end of the first capacitor, and a second end of the auxiliary winding La is connected to the second end of the auxiliary switch tube Qaux.
In one embodiment, the power supply winding Lc and/or the auxiliary winding may also be used to supply power to the primary-side controller (and other controllers or circuits), and the power supply winding Lc may not participate in the charging and discharging process of the charging and discharging module, or may participate therein.
Furthermore, the flyback converter may further include a power supply energy storage module (the power supply energy storage module may include, for example, the power supply energy storage capacitor C0 shown in fig. 5, 9, and 13), and a primary side controller 131 for controlling the main switching tube Q and the auxiliary switching tube Qaux (the primary side controller 131 may be understood as a part of the control module 13), and the primary side controller 131 may connect a control terminal (e.g., a gate thereof) of the main switching tube Q and a control terminal (e.g., a gate thereof) of the auxiliary switching tube Qaux.
In the circuit shown in fig. 5, an auxiliary winding may be used to supply power to a power supply energy storage module, wherein a first end of the auxiliary winding La is connected to the power supply energy storage module (e.g., a power supply energy storage capacitor C0) through a power supply diode D0, an anode of the power supply diode D0 is connected to the first end of the auxiliary winding La, the first end of the power supply energy storage module is connected to a power supply terminal of the primary side controller, a second end of the auxiliary winding La is connected to ground through the auxiliary switching tube Qaux, and a second end of the power supply energy storage module (e.g., a power supply energy storage capacitor C0) is connected to ground.
In the circuit shown in fig. 9, another power supply winding may be used to supply power to the power supply and energy storage module, but the power supply winding does not participate in the charging and discharging process of the charging and discharging module; the additional winding module 11 further includes a power supply winding Lc, and the power supply winding Lc and the secondary winding Ls mutually induce; the first end of the power supply winding Lc is connected to the power supply energy storage module (for example, a power supply energy storage capacitor C0) through a power supply diode D0, the positive electrode of the power supply diode D0 is connected to the first end of the power supply winding Lc, the first end of the power supply energy storage module (for example, a power supply energy storage capacitor C0) is connected to the power supply end of the primary side controller 131, and the second end of the power supply winding Lc and the second end of the power supply energy storage module (for example, a power supply energy storage capacitor C0) are both connected to the ground.
In the circuit shown in fig. 13, the power supply winding is used to supply power to the power supply and energy storage module, and at the same time, the power supply winding is also involved in the charging and discharging process of the charging and discharging module. Wherein the first end of the power supply winding Lc is connected to the first end of the first capacitor C1, the first end of the power supply winding Lc is further connected to the first end of the power supply energy storage module (e.g., power supply energy storage capacitor C0) through a power supply diode D0, the positive electrode of the power supply diode D0 is connected to the first end of the power supply winding Lc, the second end of the power supply winding Lc is connected to the first end of the auxiliary winding La, the second end of the auxiliary winding is connected to the second end of the auxiliary switching tube Qaux through the path guiding unit 121 (e.g., fifth diode D5 therein), the second end of the first capacitor C1 is connected to the second end of the power supply winding Lc through the path guiding unit (e.g., fourth diode D4 therein), and the second end of the first capacitor C1 is connected to the first end of the auxiliary switching tube Qaux; the second end of the first capacitor C1 and the second end of the power supply energy storage module are both connected to ground.
It can be seen that, in the case of the additional winding module having two windings, in the embodiment of fig. 10 to 13, the magnitude relationship between the first voltage and the fourth voltage may be realized by using the coupling of one winding during charging and the coupling of two windings during discharging without using the second capacitor C2.
Wherein the path guiding unit 121 is operable to:
in the first time period, the power supply winding Lc is guided to charge the first capacitor;
and in the second time period, the first capacitor C1 is led to discharge the power supply winding Lc and the auxiliary winding La which are connected in series.
In a further aspect, referring to fig. 11 to 13, the path guiding unit 121 includes a fourth diode D4 and a fifth diode D5.
The anode of the fourth diode D4 is connected between the second end of the first capacitor C1 and the first end of the auxiliary winding La, and the cathode of the fourth diode D4 is connected to the first end of the auxiliary winding; the fifth diode D5 is connected between the second end of the auxiliary winding La and the second end of the auxiliary switching tube Qaux, and the anode of the fifth diode D5 is connected to the second end of the auxiliary winding La.
Further, during charging, the first capacitor C1 can be charged by the feeding winding because the fourth diode D4 is turned on and the fifth diode D5 is turned off, and during discharging, the feeding winding and the auxiliary winding connected in series can be discharged because the fourth diode D4 is turned off and the fifth diode D5 is turned on.
In one embodiment, the flyback converter further includes clamping modules connected to two ends of the primary winding Lp, which may be RCD clamping modules or other clamping modules, and no matter what kind of clamping module is used, the scope of the embodiment of the present invention is not departing from.
Specifically, referring to fig. 5, 9 and 13, the clamping module includes a clamping resistor R, a clamping capacitor C and a clamping diode D;
the first end of the clamping resistor R after being connected with the clamping capacitor C in parallel is connected with the first end of the primary winding Lp, the second end of the clamping resistor R after being connected with the clamping capacitor C in parallel is connected with the second end of the primary winding Lp through the clamping diode D, and the positive electrode of the clamping diode D is connected with the second end of the primary winding Lp.
In addition, in the circuits shown in fig. 5, 9 and 13, the first end of the power supply energy storage capacitor C0 is also connected to the voltage source Vbulk through the resistor R1, and the main switching tube Q is grounded through the resistor R6. The first end of the primary winding Lp is externally connected through a leakage inductor lk, and the first end of the auxiliary winding La is externally connected through a leakage inductor L1k 1.
In the circuits shown in fig. 5, 9, and 13, on the secondary side, the first end of the secondary winding is further connected to the first end of the output capacitor C3 for feeding back the output voltage Vo to the load, the second end of the output capacitor C3 is grounded, the second end of the secondary winding Ls is grounded via the synchronous rectifier, the first end of the secondary winding Ls is further connected to the first end of the resistor R3 and the first end of the resistor R7, the second end of the resistor R7 is grounded via the resistor R5, the second end of the resistor R3 is connected to the anode of the light emitting diode D7, the cathode of the light emitting diode D7 is grounded via the zener diode D6, the zener diode D6 is further connected between the resistor R5 and the resistor R7, the resistor R4 and the capacitor C6 are connected in series, the one end of the resistor R6 is connected between the zener diode D7, and the other end of the resistor R7 and the resistor R686.
In one embodiment, please refer to fig. 4 and 12, the flyback converter further includes a control module 13, and the control module 13 is connected to the control end of the synchronous rectifier Qr; the control module 13 may further connect the control end of the main switching tube Q and the control end of the auxiliary switching tube Qaux; under the condition that the synchronous rectifier Qr, the main switch tube Q and the auxiliary switch tube Qaux adopt NMOS, the control end is a grid.
Further, the control module 13 may include a primary side controller 131 and/or a synchronous rectification controller 13, and the control module 13 may be configured to implement a control method of the flyback converter circuit, and further, in some embodiments, if the control method only includes the control of the synchronous rectification transistor Qr, an execution subject of the control method may be understood as the synchronous rectification controller 132, and in some embodiments, if the control method only includes the control of the main switching transistor Q and the auxiliary switching transistor Qaux, an execution subject of the control method may be understood as the primary side controller 131; in some embodiments, if the control method includes controlling the main switch Q, the auxiliary switch Qaux and the synchronous rectifier Qr, the main controller 131 and the synchronous rectifier controller 132 may be implemented by the control method.
In addition, a case where the primary-side controller 131 and the synchronous rectification controller 132 are integrated into one controller is not excluded, and in this case, the controller is mainly executed as the control method, and the foregoing power supply to the primary-side controller 131 may be regarded as the power supply to the controller. The power supply of the synchronous rectification controller 132 may be the same as or different from that of the primary side controller 131, and in the illustrated embodiment, the power supply of the synchronous rectification controller 132 is obtained from the secondary winding, wherein the power supply terminal of the synchronous rectification controller 132 may be connected to the first terminal of the capacitor C7.
In addition, in order to realize the control method, the primary side controller and the synchronous rectification controller are configured by other circuits.
In the illustrated example, the CS terminal of the primary side controller 131 is further connected between the main switching tube Q and the resistor R6. The FB terminal of the primary-side controller 131 may be grounded via a capacitor C4, and may also be grounded via a transistor Q1, where the transistor Q1 may be, for example, a transistor in an optocoupler.
The control module is used for executing a control method of the flyback conversion circuit.
Referring to fig. 14, a method for controlling a flyback converter circuit includes:
s21: and when the main switching tube is kept to be switched off and the synchronous rectifying tube is kept to be switched on, the synchronous rectifying tube is switched off according to the excitation inductive current corresponding to the primary winding. Specifically, the synchronous rectifier tube may be turned off when it is detected that the exciting inductor current corresponding to the primary winding drops to zero.
Please refer to fig. 15, fig. 6, and the control process and the control sequence, in combination with the circuit of fig. 5.
Before step S21, the method may further include: s22: after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on;
step S21 specifically includes:
s211: when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and the auxiliary switching tube is turned on.
Further, for convenience of describing specific timing sequences, the following labels are described first:
DRV, representing the control signal of the main switching tube Q, and also being understood as the grid voltage or the grid source voltage;
ZVS _ DRV, which represents the control signal of the auxiliary switching tube Qaux, and can also be understood as the gate voltage or gate-source voltage thereof;
vds, representing the source-drain voltage of the main switching tube Q;
iLm, characterizing the exciting inductance current corresponding to the primary winding;
the iLlk represents the leakage inductance current corresponding to the primary winding;
VC, representing the voltage at the first end of the first capacitor;
vds _ SR, representing the source-drain voltage of the synchronous rectifier tube Qr;
vo, representing the output voltage of the secondary side output to the load;
ns, which characterizes the number of turns of the secondary winding Ls;
np, which characterizes the number of turns of the primary winding Lp;
vin, characterizing the input voltage on the primary side to the primary winding Lp.
One control sequence (which may be, for example, but is not limited to, a control sequence in the QR mode) will be described below with reference to fig. 6:
at time t0, the main switch tube Q is turned on at zero voltage, the synchronous rectifier tube Qr on the secondary side is turned off at this time, the source-drain voltage of the synchronous rectifier tube Qr is subjected to the back voltage Vds _ SR ═ Vin × Ns/Np + Vo, and the transformer leakage inductance current rises together with the excitation inductance.
At time t1, the main switch Q is turned off, the energy of the transformer leakage inductance is absorbed by the RCD circuit, the body diode of the synchronous rectifier Qr on the secondary side is turned on, and then the synchronous rectifier controller 132 turns on the synchronous rectifier Qr (corresponding to step S22). The auxiliary winding La charges the clamped first capacitor C1, the second capacitor C2 and the power supply storage capacitor C0, the first diode D1 is turned on, the second diode D2 and the third diode D3 are turned off, and the first capacitor C1 and the second capacitor C2 are connected in series to store energy.
When the exciting inductor current drops to 0 at time t2, the auxiliary switching tube Qaux is turned on and the secondary synchronous rectifier Qr is turned off (corresponding to step S211). At the moment, the second diode D2 and the third triode D3 are conducted, the first diode D1 is cut off, the first capacitor C1 and the second capacitor C2 are connected in parallel to charge the auxiliary winding La, and the voltage of the auxiliary winding La is halved due to the fact that the voltage of the first capacitor C1 and the voltage of the second capacitor C2 which are connected in parallel are halved, and the exciting inductive current of the transformer reversely rises;
at the time t3, the auxiliary switching tube Qaux is turned off, and after a short dead time td, the body diode of the main switching tube Q is turned on, the source-drain voltage of the main switching tube Q is changed into zero, and zero-voltage opening can be realized, wherein the dead time is matched with the time for enabling the source-drain voltage of the main switching tube Q to be reduced to zero by the reverse exciting current;
at time t4, the main switching tube Q is turned on again, and the next cycle begins.
Please refer to fig. 16, fig. 7, and the control process and the control sequence, in combination with the circuit of fig. 5.
Before step S21, the method further includes:
s22: after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on;
s23: after delaying the first time, opening the auxiliary switch tube;
step S21 may specifically include:
s212: when the main switching tube is kept to be turned off, the synchronous rectifying tube is kept to be turned on, and the auxiliary switching tube is kept to be turned on, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifying tube is turned off.
It can be seen that the auxiliary switch tube opens earlier in the arrangement of fig. 16 than in the arrangement of fig. 15. Specifically, referring to fig. 7, after the time t1, the first time td1 is delayed, the auxiliary winding switch tube Qaux is turned on, the dead time td2 is delayed after the time t3, and the main switch tube Q is turned on, and the rest of the timing control can be understood with reference to the timing control shown in fig. 6.
The first time td1 may be any time, such as any time less than t2-t1, but not limited thereto, and the first time td1 is generally configured to avoid an oscillation time of the main switch source-drain voltage Vds after being turned off.
Please refer to fig. 17, fig. 8, which are a control process and a control sequence, in conjunction with the circuit of fig. 5. The control process and the control timing can be understood as the control process and the control timing in the DCM mode. Wherein the opening time of the auxiliary switching tube can be delayed to the resonance process.
Referring to fig. 17, before step S21, the method may further include:
s22: after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on;
step S21 may specifically include:
s213: when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and after the second time, the auxiliary switching tube is turned on.
When the flyback conversion circuit is in the DCM mode, the second time δ t satisfies the following formula:
Figure RE-GDA0002943825140000181
wherein:
tr characterizes the resonance period in DCM;
n characterizes the number of troughs of resonance in DCM mode.
A control sequence (for example, but not limited to, a control sequence in DCM mode) will be described below with reference to fig. 8:
at time t0, the main switching tube Q is turned on at zero voltage, the synchronous rectifier Qr on the secondary side is turned off, and the back voltage applied to the ds of the synchronous rectifier Qr is Vds _ SR — Vin × Ns/Np + Vo. The leakage inductance current of the transformer rises along with the excitation inductance;
at time t1, the main switch Q is turned off, the energy of the transformer leakage inductance is absorbed by the RCD circuit, the body diode of the synchronous rectifier Qr on the secondary side is turned on first, and then the synchronous rectifier controller turns on the synchronous rectifier Qr (corresponding to step S22). The auxiliary winding charges a first capacitor C1, a second capacitor C2 and a power supply energy storage capacitor C0, the first diode D2 is conducted, the second diode D2 and the third diode D3 are cut off, and the first capacitor C1 and the second capacitor C2 are connected in series to store energy.
When the excitation inductor current of the primary winding drops to 0 at time t2, the synchronous rectifier Qr on the secondary side is turned off (corresponding to the process of turning off the synchronous rectifier in step S213), and the resonant phase is entered. At this time, the first diode D1, the second diode D2, and the third diode D3 are all turned off.
At time t3, the auxiliary switching tube Qaux is opened, while the synchronous rectifier Qr on the secondary side is in the off state (corresponding to the opening of the auxiliary switching tube after a second time in step S213, where the second time δ t can be understood as t3-t2, i.e., δ t is t3-t 2). The second diode D2 and the third diode D3 are conducted, the first capacitor C1 and the second capacitor C2 are connected in parallel to charge the auxiliary winding, and the voltage of the parallel connection of the capacitors C1 and C2 is halved, so that the auxiliary winding is chargedThe voltage of the auxiliary winding is halved, and the exciting inductive current of the transformer reversely rises. After a short dead time td, the main switching tube Q is turned on. The value range of t3-t2 can be understood by referring to the foregoing description about δ t, and in one example, the value range may be:
Figure RE-GDA0002943825140000191
at time t4, the auxiliary switch Qaux is turned off and the main switch Q is turned on after a short dead time td.
At time t5, the main switching tube Q is turned on again, and a new cycle begins.
In addition, the control process and the control sequence described above are not limited to the circuit shown in fig. 5, and may be applied to any circuit scheme in the embodiment of the present invention.
Besides, based on the circuit shown in fig. 13, the operation process thereof can be understood with reference to the above operation method.
Specifically, the method comprises the following steps:
when the main switching tube Q is turned off, the power supply winding Lc charges the first capacitor C1 and the power supply energy storage capacitor C0 through the power supply diode D0 and the fourth diode D4, respectively, and when the first capacitor C1 is fully charged, the voltage value of the first capacitor C1 is lower than the voltage of the series connection of the power supply winding Lc and the auxiliary winding La.
When the excitation current of the transformer drops to 0, the auxiliary switching tube Qaux is turned on, the first capacitor C1 charges the power supply winding Lc and the auxiliary winding La through the fifth diode D5 and the auxiliary switching tube Qaux, and at this time, the voltage of the series connection of the power supply winding Lc and the auxiliary winding La is coupled to the secondary winding through the transformer, so that the voltage of the secondary winding is lower than the output voltage Vo, which further helps to avoid the bilateral common connection, thereby helping to ensure that the tubes are not easy to be burned out and fail on both sides due to the bilateral common connection.
In summary, the embodiments of the present invention can not only implement zero-voltage turn-on of the flyback converter, but also avoid the problem of bilateral common connection that may exist in the conventional zero-voltage turn-on active clamp flyback power supply.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (23)

1. A flyback converter circuit, comprising: the synchronous rectifier comprises a primary winding, a secondary winding, an additional winding module, a charge-discharge module, a main switching tube and a synchronous rectifying tube; the primary winding and the secondary winding are mutually inductive, and the additional winding module and the secondary winding are mutually inductive; the charging and discharging module is connected with the additional winding module; the synchronous rectifier tube is connected between the secondary winding and the ground, and the main switching tube is connected between the primary winding and the ground;
the additional winding module is used for:
in a first time period, inducing a first voltage of the secondary winding to form a second voltage, and charging the charge and discharge module by using the second voltage;
in a second time period, discharging of the charge-discharge module is obtained to form a third voltage, and the third voltage is induced to the secondary winding so as to form a fourth voltage on the secondary winding; the absolute value of the first voltage is higher than the maximum value of the absolute value of the fourth voltage, and the first time period and the second time period are different time periods;
the charge and discharge module is used for:
receiving the charging of the additional winding module in the first time period, and storing energy;
releasing the stored electrical energy to the additional winding module during the second time period.
2. The flyback converter circuit of claim 1, wherein the charge-discharge module comprises a first capacitor, an auxiliary switch tube and a path guiding unit;
a first end of the first capacitor is directly or indirectly connected to a first end of the additional winding module, a second end of the first capacitor is directly or indirectly connected to a first end of the auxiliary switching tube, and a second end of the auxiliary switching tube is directly or indirectly connected to a second end of the additional winding module; the path guide unit is connected with at least one end of the first capacitor and two ends of the additional winding module;
the auxiliary switch tube is used for:
remain off for the first period of time and remain on for the second period of time;
the path guiding unit is used for:
directing the additional winding module to charge the first capacitor during the first time period;
and guiding the first capacitor to charge the additional winding module in the second time period.
3. The flyback converter circuit of claim 2, wherein the charge-discharge module further comprises a second capacitor;
the second end of the first capacitor is connected with the first end of the path guiding unit, the first end of the second capacitor is connected with the second end of the path guiding unit, the second end of the second capacitor is connected with the first end of the auxiliary switching tube, and the path guiding unit is also respectively connected with the first end of the first capacitor and the second end of the second capacitor;
the path guiding unit is specifically configured to:
directing the additional winding module to charge the first capacitor and the second capacitor in series during the first time period;
and in the second time period, the first capacitor is led to be connected with the second capacitor in parallel and then the additional winding module is discharged.
4. The flyback converter circuit of claim 3 wherein the path directing unit comprises a first diode, a second diode, a third diode;
the positive pole of the first diode is connected with the second end of the first capacitor, the negative pole of the first diode is connected with the first end of the second capacitor, the positive pole of the second diode is connected with the first end of the second capacitor, the negative pole of the second diode is connected with the first end of the first capacitor, the positive pole of the third diode is connected with the second end of the second capacitor, and the negative pole of the third diode is connected with the second end of the first capacitor.
5. The flyback converter circuit of claim 3 wherein the additional winding module comprises an auxiliary winding; the first end of the auxiliary winding is connected to the first end of the first capacitor, and the second end of the auxiliary winding is connected to the second end of the auxiliary switching tube.
6. The flyback converter circuit of claim 5, further comprising a power supply energy storage module and a primary side controller for controlling the main switching tube and the auxiliary switching tube, wherein the additional winding module further comprises a power supply winding, and the power supply winding and the secondary winding are mutually inductive;
the first end of the power supply winding is connected with the first end of the power supply energy storage module through a power supply diode, the anode of the power supply diode is connected with the first end of the power supply winding, the first end of the power supply energy storage module is connected with the power supply end of the primary side controller, and the second end of the power supply winding and the second end of the power supply energy storage module are both connected to the ground.
7. The flyback converter circuit of claim 5, further comprising a power supply energy storage module and a primary side controller for controlling the main switching tube and the auxiliary switching tube;
the first end of the auxiliary winding is connected with the power supply energy storage module through a power supply diode, the anode of the power supply diode is connected with the first end of the auxiliary winding, the first end of the power supply energy storage module is connected with the power supply end of the primary side controller, the second end of the auxiliary winding is connected to the ground through the auxiliary switch tube, and the second end of the power supply energy storage module is connected to the ground.
8. The flyback conversion circuit of claim 2, further comprising a power supply energy storage module and a primary side controller for controlling the main switching tube and the auxiliary switching tube, wherein the additional winding module comprises an auxiliary winding and a power supply winding; the power supply winding and the secondary winding are mutually inductive, and the auxiliary winding and the secondary winding are mutually inductive;
the first end of the power supply winding is connected with the first end of the first capacitor, the first end of the power supply winding is further connected with the first end of the power supply energy storage module through a power supply diode, the anode of the power supply diode is connected with the first end of the power supply winding, the second end of the power supply winding is connected with the first end of the auxiliary winding, the second end of the auxiliary winding is connected with the second end of the auxiliary switching tube through the path guiding unit, the second end of the first capacitor is connected with the second end of the power supply winding through the path guiding unit, and the second end of the first capacitor is connected with the first end of the auxiliary switching tube; the second end of the first capacitor and the second end of the power supply energy storage module are both connected to the ground;
the path guiding unit is used for:
directing the power supply winding to charge the first capacitor during the first time period;
and in the second time period, the first capacitor is guided to discharge the power supply winding and the auxiliary winding which are connected in series.
9. The flyback converter circuit of claim 8, wherein the path directing unit comprises a fourth diode and a fifth diode;
the anode of the fourth diode is connected between the second end of the first capacitor and the first end of the auxiliary winding, and the cathode of the fourth diode is connected with the first end of the auxiliary winding; the fifth diode is connected between the second end of the auxiliary winding and the second end of the auxiliary switching tube, and the anode of the fifth diode is connected with the second end of the auxiliary winding.
10. The flyback converter circuit of claim 2, further comprising a control module, the control module being connected to the control terminal of the synchronous rectifier tube;
the control module is used for:
and when the main switching tube is kept to be switched off and the synchronous rectifying tube is kept to be switched on, the synchronous rectifying tube is switched off according to the excitation inductive current corresponding to the primary winding.
11. The flyback converter circuit of claim 10, wherein the control module is further connected to the control terminal of the main switching tube and the control terminal of the auxiliary switching tube, respectively;
the control module is specifically configured to:
after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on;
when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and the auxiliary switching tube is turned on.
12. The flyback converter circuit of claim 10, wherein the control module is further connected to the control terminal of the main switching tube and the control terminal of the auxiliary switching tube, respectively;
the control module is specifically configured to:
after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on, and the auxiliary switching tube is turned on after delaying for the first time;
when the main switching tube is kept to be turned off, the synchronous rectifying tube is kept to be turned on, and the auxiliary switching tube is kept to be turned on, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifying tube is turned off.
13. The flyback converter circuit of claim 10, wherein the control module is further connected to the control terminal of the main switching tube and the control terminal of the auxiliary switching tube, respectively;
the control module is specifically configured to:
after the synchronous rectifier tube and the auxiliary switching tube are kept turned off and the main switching tube is turned off, the synchronous rectifier tube is turned on;
when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and after the second time, the auxiliary switching tube is turned on.
14. The flyback converter circuit of claim 13, wherein the second time δ t satisfies the following equation when the flyback converter circuit is in DCM:
Figure RE-FDA0002943825130000041
wherein:
tr characterizes the resonance period in DCM;
n characterizes the number of troughs of resonance in DCM mode.
15. The flyback converter circuit of any of claims 11 to 13, wherein the control module comprises a primary side controller for controlling the main switching transistor and the charging and discharging module, and a synchronous rectification controller for controlling the synchronous rectification transistor.
16. The flyback converter circuit of any of claims 1 to 13, further comprising a clamping module connected across the primary winding.
17. The flyback converter circuit of claim 16 wherein the clamping module comprises a clamping resistor, a clamping capacitor, and a clamping diode;
the first end of the clamping resistor connected with the clamping capacitor in parallel is connected with the first end of the primary winding, the second end of the clamping resistor connected with the clamping capacitor in parallel is connected with the second end of the primary winding through the clamping diode, and the anode of the clamping diode is connected with the second end of the primary winding.
18. A control method of the flyback converter circuit as claimed in claim 2, applied to a control module, said control module is respectively connected to the control terminal of the auxiliary switch tube, the control terminal of the synchronous rectifier tube, and the control terminal of the main switch tube,
the control method comprises the following steps:
and when the main switching tube is kept to be switched off and the synchronous rectifying tube is kept to be switched on, the synchronous rectifying tube is switched off according to the excitation inductive current corresponding to the primary winding.
19. The control method according to claim 18,
according to the excitation inductive current corresponding to the primary winding, before controlling the synchronous rectifier tube, the method further comprises:
and after the synchronous rectifier tube and the auxiliary switching tube are kept off and the main switching tube is turned off, the synchronous rectifier tube is turned on.
20. The control method according to claim 19,
according to the excitation inductive current that primary winding corresponds, turn off synchronous rectifier, specifically include:
when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and the auxiliary switching tube is turned on.
21. The control method of claim 19, after opening the synchronous rectifier tube, further comprising: after delaying the first time, opening the auxiliary switch tube;
according to the excitation inductive current that primary winding corresponds, turn off synchronous rectifier, specifically include:
when the main switching tube is kept to be turned off, the synchronous rectifying tube is kept to be turned on, and the auxiliary switching tube is kept to be turned on, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifying tube is turned off.
22. The control method according to claim 19, wherein controlling the synchronous rectifier according to the exciting inductor current corresponding to the primary winding specifically comprises:
when the main switching tube is kept to be turned off, the synchronous rectifier tube is kept to be turned on, and the auxiliary switching tube is kept to be turned off, if the fact that the exciting inductance current corresponding to the primary winding is reduced to zero is detected, the synchronous rectifier tube is turned off, and after the second time, the auxiliary switching tube is turned on.
23. The control method according to claim 22, wherein the second time δ t satisfies the following equation when the flyback converter circuit is in DCM:
Figure RE-FDA0002943825130000061
wherein:
tr characterizes the resonance period in DCM;
n characterizes the number of troughs of resonance in DCM mode.
CN202110166647.1A 2021-02-07 2021-02-07 Flyback converter circuit and control method thereof Pending CN112737305A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113258784A (en) * 2021-06-08 2021-08-13 成都芯源系统有限公司 Power supply circuit of switching power supply and control method thereof

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111585444A (en) * 2019-02-15 2020-08-25 英飞凌科技奥地利有限公司 Switching converter and method for operating a switching converter

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111585444A (en) * 2019-02-15 2020-08-25 英飞凌科技奥地利有限公司 Switching converter and method for operating a switching converter

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113258784A (en) * 2021-06-08 2021-08-13 成都芯源系统有限公司 Power supply circuit of switching power supply and control method thereof
CN113258784B (en) * 2021-06-08 2022-12-16 成都芯源系统有限公司 Power supply circuit of switching power supply and control method thereof

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