CN111049391A - Off-line flyback converter and power supply equipment - Google Patents
Off-line flyback converter and power supply equipment Download PDFInfo
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- CN111049391A CN111049391A CN201911346158.3A CN201911346158A CN111049391A CN 111049391 A CN111049391 A CN 111049391A CN 201911346158 A CN201911346158 A CN 201911346158A CN 111049391 A CN111049391 A CN 111049391A
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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
- H02M3/33569—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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- 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 discloses an off-line flyback converter, which comprises: the power supply comprises a power supply input end, a transformer module, a main control module, a first switching tube module, an output module and a power supply output end, wherein the output module comprises a second switching tube module and an energy storage module; the transformer module is used for storing electric energy input by the power supply input end; the main control module is used for controlling the working state of the first switching tube module; when the first switching tube module is in an open state, the transformer module works in an energy storage mode; when the first switching tube module is in an off state, the transformer module works in a power transmission mode; when the transformer module works in a power transmission mode, the transformer module transmits electric energy to the power output end and the energy storage module; when the transformer module works in the energy storage mode, the energy storage module transmits electric energy to the voltage output end. The invention also discloses a power supply device. By adopting the embodiment of the invention, high-efficiency synchronous rectification can be realized at lower cost without the support of a special control chip.
Description
Technical Field
The invention relates to the technical field of electronics, in particular to an off-line flyback converter and power supply equipment.
Background
An off-line Flyback Converter, also called Flyback Converter, referred to as Flyback Converter for short, is widely applied to the design of power supplies with low power converted from alternating current/direct current (AC/DC) to direct current/direct current (DC/DC), such as power adapters, USB chargers, etc., due to its characteristics of simplicity, reliability, low cost, etc. Flyback is divided into synchronous rectification and asynchronous rectification according to different rectification modes. The asynchronous rectification adopts a diode (generally a schottky diode) for rectification, has a simple structure, and has relatively low efficiency in the application scenes of low voltage and high load. The MOS tube is used as a rectifying component for synchronous rectification, so that the conduction resistance is low, the power conversion efficiency is high, and the advantage of the synchronous rectification is more obvious compared with the asynchronous rectification efficiency in the application scene of low voltage and high load. Although Flyback with synchronous rectification has higher power conversion efficiency than Flyback with asynchronous rectification, in a common synchronous rectification design, the switch of the rectification MOS transistor is generally controlled by an IC, which may be an independent device, such as UCC24610 of TI; the chip can also be integrated in a power chip, such as MPX2001 of MPS, and the use of a special IC increases the material cost and limits the chip type selection range.
Disclosure of Invention
The embodiment of the invention aims to provide an off-line flyback converter and power supply equipment, and compared with an asynchronous rectification scheme, the conversion efficiency is obviously improved; compared with a synchronous rectification scheme, the synchronous rectification method has the advantages of low requirement on the control chip, no need of special control chip support, low cost and strong practicability.
To achieve the above object, an embodiment of the present invention provides an off-line flyback converter, including: the power supply comprises a power supply input end, a transformer module, a main control module, a first switching tube module, an output module and a power supply output end, wherein the output module comprises a second switching tube module and an energy storage module; wherein the content of the first and second substances,
the transformer module is respectively connected with the power input end, the first switching tube module and the output module, and is used for storing electric energy input by the power input end and outputting the electric energy to the energy storage module and the power output end when the second switching tube module is opened;
the main control module is connected with the first switch tube module and is used for controlling the working state of the first switch tube module; when the first switching tube module is in an open state, the second switching tube module is in a closed state, and the transformer module works in an energy storage mode; when the first switch tube module is in an off state, the second switch tube module is in an on state, and the transformer module works in a power transmission mode;
when the transformer module works in a power transmission mode, the transformer module transmits electric energy to the power output end and the energy storage module; when the transformer module works in an energy storage mode, the energy storage module transmits electric energy to the voltage output end.
Compared with the prior art, the off-line flyback converter disclosed by the invention has the advantages that the working state of the first switching tube module is controlled by the main control module, when the first switching tube module is in the opening state, the transformer module works in the energy storage mode, and the energy storage module transmits electric energy to the voltage output end; when the first switch tube module is in an off state, the transformer module works in a power transmission mode, and the transformer module transmits electric energy to the power output end and the energy storage module. Compared with an asynchronous rectification scheme adopted in the prior art, the off-line flyback converter disclosed by the invention has the advantages that the conversion efficiency is obviously improved; compared with a synchronous rectification scheme adopted in the prior art, the synchronous rectification method has the advantages of low requirement on a control chip, no need of special control chip support, low cost and strong practicability.
As a refinement of the above, the transformer module comprises a transformer comprising a primary winding and at least two secondary windings.
As an improvement of the above scheme, the second switching tube module is respectively connected to the energy storage module, the transformer module and the power output end; when the transformer module works in a power transmission mode, the transformer module transmits electric energy to the power output end and the energy storage module through the second switching tube module.
As an improvement of the above scheme, the second switch tube module is respectively connected to the energy storage module and the ground terminal, and the transformer module is further respectively connected to the energy storage module and the power output terminal.
As an improvement of the above scheme, the offline flyback converter further comprises a feedback module; wherein the content of the first and second substances,
the feedback module is respectively connected with the main control module and the power output end and used for generating a feedback signal to the main control module according to the voltage output by the power output end so that the main control module controls the working state of the first switch tube module according to the feedback signal.
As an improvement of the above scheme, the first switching tube module comprises a first NMOS tube; wherein the content of the first and second substances,
the grid electrode of the first NMOS tube is connected with the main control module, the drain electrode of the first NMOS tube is connected with the primary winding, and the source electrode of the first NMOS tube is grounded.
As an improvement of the above scheme, the second switching tube module includes a second NMOS tube, and the energy storage module includes a capacitor; wherein the content of the first and second substances,
the grid electrode of the second NMOS tube is connected with the first end of the secondary winding, the drain electrode of the second NMOS tube is connected with the power output end, the source electrode of the second NMOS tube is connected with the second end of the secondary winding, and the third end of the secondary winding is grounded;
and the first end of the capacitor is connected with the drain electrode of the second NMOS tube, and the second end of the capacitor is grounded.
As an improvement of the above scheme, the second switching tube module includes a second PMOS tube, and the energy storage module includes a capacitor; wherein the content of the first and second substances,
the grid electrode of the second PMOS tube is connected with the third end of the secondary winding, the drain electrode of the second PMOS tube is grounded, the source electrode of the second PMOS tube is connected with the second end of the secondary winding, and the first end of the secondary winding is connected with the power supply output end;
the first end of the capacitor is connected with the first end of the secondary winding, and the second end of the capacitor is grounded.
In order to achieve the above object, an embodiment of the present invention further provides a power supply device, including the off-line flyback converter described in any of the above embodiments.
Drawings
Fig. 1 is a schematic structural diagram of an off-line flyback converter according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an off-line flyback converter according to a preferred embodiment of the present invention;
fig. 3 is a circuit diagram of an off-line flyback converter according to a preferred embodiment of the present invention;
fig. 4 is a schematic diagram of a current direction of a transformer in an off-line flyback converter operating in an energy storage mode according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a current direction of a transformer in an off-line flyback converter operating in a power transmission mode according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an off-line flyback converter according to another preferred embodiment of the present invention;
fig. 7 is a circuit diagram of an off-line flyback converter according to another preferred embodiment of the present invention.
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.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an offline flyback converter according to an embodiment of the present invention; the off-line Flyback Converter is an off-line Flyback Converter (Flyback Converter) adopting a synchronous rectification mode, and comprises: the power supply comprises a power supply input end IN, a transformer module 1, a main control module 2, a first switching tube module 3, an output module 4 and a power supply output end OUT, wherein the output module 4 comprises a second switching tube module 41 and an energy storage module 42; wherein the content of the first and second substances,
the transformer module 1 is respectively connected to the power input terminal IN, the first switching tube module 3 and the output module 4, and the transformer module 1 is configured to store electric energy input by the power input terminal IN and output electric energy to the energy storage module 42 and the power output terminal OUT when the second switching tube module 41 is turned on;
the main control module 2 is connected with the first switch tube module 3, and the main control module 2 is used for controlling the working state of the first switch tube module 3; when the first switching tube module 3 is in an open state, the second switching tube module 41 is in a closed state, and the transformer module 1 works in an energy storage mode; when the first switch tube module 3 is in an off state, the second switch tube module 41 is in an on state, and the transformer module 1 works in a power transmission mode;
when the transformer module 1 works in a power transmission mode, the transformer module 1 transmits electric energy to the power output end OUT and the energy storage module 42; when the transformer module 1 operates in the energy storage mode, the energy storage module 42 transmits electric energy to the voltage output terminal OUT.
Preferably, the off-line flyback converter further includes a feedback module 5; wherein the content of the first and second substances,
the feedback module 5 is respectively connected to the main control module 2 and the power output end OUT, and is configured to generate a feedback signal to the main control module 2 according to the voltage output by the power output end OUT, so that the main control module 2 controls the working state of the first switching tube module 3 according to the feedback signal.
Specifically, the main control module 2 is responsible for controlling the working state of the first switching tube module 3, the feedback module 5 feeds back the output condition to the main control module 2, and the main control module 2 determines information such as duty ratio of time for opening the first switching tube module 3 according to a feedback signal. The transformer module 1 is mainly responsible for storing and transmitting energy, and is also responsible for controlling the operating state of the second switch tube module 41.
It should be noted that the second switch tube module 41 and the energy storage module 42 in the output module 4 have two connection relationships, which are respectively described in two embodiments.
Example one
Referring to fig. 2, fig. 2 is a schematic structural diagram of an off-line flyback converter according to a preferred embodiment of the present invention; the second switching tube module 41 is respectively connected with the energy storage module 42, the transformer module 1 and the power output end OUT; when the transformer module 1 works in the power transmission mode, the transformer module 1 transmits electric energy to the power output end OUT and the energy storage module 42 through the second switching tube module 41.
Referring to fig. 3, the transformer module 1 includes a transformer T1, and the transformer T1 includes a primary winding n0 and at least two secondary windings (such as the secondary winding n1 and the secondary winding n2 in fig. 3). The feedback module comprises a feedback circuit Feed Back. It should be noted that, circuits that can generate feedback signals according to output voltages in the prior art are all applicable to this scheme, and are not limited herein.
The main control module 2 includes a control chip U1, and any Switch controller chip may be used. For example, the control chip U1 can be classified into: PWM (pulse width modulation), PFM (pulse frequency modulation), or a mixture of both. In the PWM mode, a switch driving pin of the control chip U1 can periodically output high level and low level, and the duty ratio of the high level and the low level is determined by a feedback circuit; in the PFM mode, a "constant on time" or a "constant off time" is used, that is, one of high and low levels of the control signal is constant, and the other is determined by a feedback circuit.
The first switch tube module 3 comprises a first NMOS tube Q1; the gate of the first NMOS transistor Q1 is connected to the main control module 2, the drain of the first NMOS transistor Q1 is connected to the primary winding, and the source of the first NMOS transistor Q1 is grounded PGND.
The second switch tube module 41 comprises a second NMOS tube Q2, and the energy storage module 42 comprises a capacitor C1; the grid electrode of the second NMOS transistor Q2 is connected to the first end of the secondary winding, the drain electrode of the second NMOS transistor Q2 is connected to the power output end OUT, the source electrode of the second NMOS transistor Q2 is connected to the second end of the secondary winding, and the third end of the secondary winding is grounded GND; the first end of the capacitor C1 is connected to the drain of the second NMOS transistor Q2, and the second end of the capacitor C1 is grounded to GND.
Specifically, when the gate g of the first NMOS transistor Q1 is pulled high by the control chip U1, the first NMOS transistor Q1 is turned on, the drain d and the source s thereof are turned on, and a current flows to the primary power ground PGND through the primary winding n0 via the power input terminal IN, as shown IN fig. 4. At this time, the voltage of the same-name terminal is pulled low, the voltage of the gate g of the second NMOS transistor Q2 will be lower than the voltage of the source s, the second NMOS transistor Q2 is turned off, the drain d of the second NMOS transistor Q2 is disconnected from the source s, the current on the secondary winding of the transformer T1 is 0, the transformer T1 only has current on the primary winding, as the current increases, the magnetic field in the transformer T1 is gradually increased, and the electric energy is stored in the transformer T1 in the form of a magnetic field. During this period, since the second NMOS transistor Q2 is turned off, the secondary power output winding cannot output energy to the secondary, the current of the primary winding increases, the magnetic field excited in the magnetic circuit increases gradually, the magnetic energy increases gradually, and the output end discharges only through the capacitor C1.
Specifically, when the control chip U1 pulls the gate g level of the first NMOS transistor Q1 low, the first NMOS transistor Q1 turns off, the drain d and the source s thereof are disconnected, the voltage at the same name terminal increases, the gate g voltage of the second NMOS transistor Q2 is higher than the voltage at the source s, the second NMOS transistor Q2 turns on, and the drain d and the source s of the second NMOS transistor Q2 are turned on. At this time, the secondary winding can form a current loop, the magnetic field induces current in the secondary winding, and the energy stored in the magnetic field is released through the secondary winding. Referring to fig. 5, the induced current of the secondary power output winding of the transformer T1 flows partially to the output power output terminal OUT and partially to the capacitor C1, thereby supplementing the energy lost by the capacitor C1 when the second NMOS transistor Q2 is turned off.
Compared with an asynchronous rectification scheme using a diode as a rectification device, the off-line flyback converter provided by the embodiment of the invention has the advantage that the efficiency is obviously improved under low-voltage high-load conditions. In the traditional asynchronous rectification scheme, a Schottky diode is adopted for rectification, the voltage drop of a device is over 0.4V, the voltage drop of the device is only about 0.2V by adopting MOS tube rectification, and the conversion efficiency is obviously improved compared with the traditional asynchronous rectification scheme under the condition of low voltage and large load. Compared with a conventional synchronous rectification scheme, the embodiment of the invention has low requirement on the control chip, does not need special control chip support, can be used by most switch control chips, and has low cost and stronger practicability.
Example two
Referring to fig. 6, fig. 6 is a schematic structural diagram of an off-line flyback converter according to another preferred embodiment of the present invention; the second switch tube module 41 is respectively connected to the energy storage module 42 and the ground end GND, and the transformer module 1 is further respectively connected to the energy storage module 42 and the power output end OUT.
Referring to fig. 7, the transformer module 1 includes a transformer T1, and the transformer T1 includes a primary winding n0 and at least two secondary windings (such as the secondary winding n1 and the secondary winding n2 in fig. 3). The feedback module comprises a feedback circuit Feed Back. It should be noted that, circuits that can generate feedback signals according to output voltages in the prior art are all applicable to this scheme, and are not limited herein.
The main control module 2 includes a control chip U1, and any Switch controller chip may be used. For example, the control chip U1 can be classified into: PWM (pulse width modulation), PFM (pulse frequency modulation), or a mixture of both. In the PWM mode, a switch driving pin of the control chip U1 can periodically output high level and low level, and the duty ratio of the high level and the low level is determined by a feedback circuit; in the PFM mode, a "constant on time" or a "constant off time" is used, that is, one of high and low levels of the control signal is constant, and the other is determined by a feedback circuit.
The first switch tube module 3 comprises a first NMOS tube Q1; the gate of the first NMOS transistor Q1 is connected to the main control module 2, the drain of the first NMOS transistor Q1 is connected to the primary winding, and the source of the first NMOS transistor Q1 is grounded PGND.
The second switch tube module 41 comprises a second PMOS tube Q2, and the energy storage module 42 comprises a capacitor C1; the grid electrode of the second PMOS transistor Q2 is connected to the third end of the secondary winding, the drain electrode of the second PMOS transistor Q2 is grounded GND, the source electrode of the second PMOS transistor Q2 is connected to the second end of the secondary winding, and the first end of the secondary winding is connected to the power output end OUT; the first end of the capacitor C1 is connected with the first end of the secondary winding, and the second end of the capacitor C1 is grounded GND.
Specifically, when the gate g of the first NMOS transistor Q1 is pulled high by the control chip U1, the first NMOS transistor Q1 is turned on, the drain d and the source s thereof are turned on, and a current flows to the primary power ground PGND through the primary winding n0 via the power input terminal I N. At this time, the second PMOS transistor Q2 is turned off, the drain d and the source s of the second PMOS transistor Q2 are disconnected, the current on the secondary winding of the transformer T1 is 0, the transformer T1 only has current on the primary winding, the magnetic field in the transformer T1 is gradually increased as the current increases, and the electric energy is stored in the form of a magnetic field in the transformer T1. During this period, since the second PMOS transistor Q2 is turned off, the secondary power output winding cannot output energy to the secondary, the current of the primary winding increases, the magnetic field excited in the magnetic circuit increases gradually, the magnetic energy increases gradually, and the output end discharges only through the capacitor C1.
Specifically, when the control chip U1 pulls the gate g of the first NMOS transistor Q1 low, the first NMOS transistor Q1 is turned off, the drain d and the source s thereof are disconnected, the voltage at the same name terminal is increased, the second PMOS transistor Q2 is turned on, and the drain d and the source s of the second PMOS transistor Q2 are turned on. At this time, the secondary winding can form a current loop, the magnetic field induces current in the secondary winding, and the energy stored in the magnetic field is released through the secondary winding. The induced current of the secondary power output winding of the transformer T1 flows partially to the output power output OUT and partially to the capacitor C1, thereby supplementing the energy lost by the capacitor C1 when the second PMOS transistor Q2 is turned off.
Compared with an asynchronous rectification scheme using a diode as a rectification device, the off-line flyback converter provided by the embodiment of the invention has the advantage that the efficiency is obviously improved under low-voltage high-load conditions. In the traditional asynchronous rectification scheme, a Schottky diode is adopted for rectification, the voltage drop of a device is over 0.4V, the voltage drop of the device is only about 0.2V by adopting MOS tube rectification, and the conversion efficiency is obviously improved compared with the traditional asynchronous rectification scheme under the condition of low voltage and large load. Compared with a conventional synchronous rectification scheme, the embodiment of the invention has low requirement on the control chip, does not need special control chip support, can be used by most switch control chips, and has low cost and stronger practicability.
EXAMPLE III
Further, an embodiment of the present invention further provides a power supply device, including the off-line flyback converter described in any of the above embodiments. Illustratively, the power supply device is a power supply device such as a low-voltage output power adapter, a power board or an on-board power supply.
Compared with an asynchronous rectification scheme adopted in the prior art, the off-line flyback converter adopted by the power supply equipment disclosed by the embodiment of the invention has the advantages that the conversion efficiency is obviously improved; compared with a synchronous rectification scheme adopted in the prior art, the synchronous rectification method has the advantages of low requirement on a control chip, no need of special control chip support, low cost and strong practicability.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (9)
1. An off-line flyback converter, comprising: the power supply comprises a power supply input end, a transformer module, a main control module, a first switching tube module, an output module and a power supply output end, wherein the output module comprises a second switching tube module and an energy storage module; wherein the content of the first and second substances,
the transformer module is respectively connected with the power input end, the first switching tube module and the output module, and is used for storing electric energy input by the power input end and outputting the electric energy to the energy storage module and the power output end when the second switching tube module is opened;
the main control module is connected with the first switch tube module and is used for controlling the working state of the first switch tube module; when the first switching tube module is in an open state, the second switching tube module is in a closed state, and the transformer module works in an energy storage mode; when the first switch tube module is in an off state, the second switch tube module is in an on state, and the transformer module works in a power transmission mode;
when the transformer module works in a power transmission mode, the transformer module transmits electric energy to the power output end and the energy storage module; when the transformer module works in an energy storage mode, the energy storage module outputs voltage to transmit electric energy to the voltage output end.
2. The off-line flyback converter of claim 1 wherein the transformer module comprises a transformer including a primary winding and at least two secondary windings.
3. The off-line flyback converter of claim 2 wherein the second switching transistor module is connected to the energy storage module, the transformer module, and the power output, respectively; when the transformer module works in a power transmission mode, the transformer module transmits electric energy to the power output end and the energy storage module through the second switching tube module.
4. The off-line flyback converter of claim 2 wherein the second switching transistor module is connected to the energy storage module and a ground terminal, respectively, and the transformer module is further connected to the energy storage module and the power output terminal, respectively.
5. The off-line flyback converter of claim 1 wherein the off-line flyback converter further comprises a feedback module; wherein the content of the first and second substances,
the feedback module is respectively connected with the main control module and the power output end and used for generating a feedback signal to the main control module according to the voltage output by the power output end so that the main control module controls the working state of the first switch tube module according to the feedback signal.
6. The off-line flyback converter of claim 2 wherein the first switching tube module comprises a first NMOS tube; wherein the content of the first and second substances,
the grid electrode of the first NMOS tube is connected with the main control module, the drain electrode of the first NMOS tube is connected with the primary winding, and the source electrode of the first NMOS tube is grounded.
7. The off-line flyback converter of claim 3 wherein the second switching transistor module comprises a second NMOS transistor and the energy storage module comprises a capacitor; wherein the content of the first and second substances,
the grid electrode of the second NMOS tube is connected with the first end of the secondary winding, the drain electrode of the second NMOS tube is connected with the power output end, the source electrode of the second NMOS tube is connected with the second end of the secondary winding, and the third end of the secondary winding is grounded;
and the first end of the capacitor is connected with the drain electrode of the second NMOS tube, and the second end of the capacitor is grounded.
8. The off-line flyback converter of claim 4 wherein the second switching transistor module comprises a second PMOS transistor and the energy storage module comprises a capacitor; wherein the content of the first and second substances,
the grid electrode of the second PMOS tube is connected with the third end of the secondary winding, the drain electrode of the second PMOS tube is grounded, the source electrode of the second PMOS tube is connected with the second end of the secondary winding, and the first end of the secondary winding is connected with the power supply output end;
the first end of the capacitor is connected with the first end of the secondary winding, and the second end of the capacitor is grounded.
9. A power supply apparatus comprising an off-line flyback converter as claimed in any one of claims 1 to 8.
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| CN1299529A (en) * | 1998-05-07 | 2001-06-13 | 艾利森电话股份有限公司 | Continuous mode flyback converter |
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| CN101132150A (en) * | 2006-08-24 | 2008-02-27 | 台达电子工业股份有限公司 | Flyback power converter with synchronous rectifier |
| CN105896987A (en) * | 2015-03-24 | 2016-08-24 | 上海英联电子系统有限公司 | Flyback converter bootstrap type synchronous rectification drive circuit |
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Application publication date: 20200421 |