CN116526849A - Self-excited active clamping circuit - Google Patents
Self-excited active clamping circuit Download PDFInfo
- Publication number
- CN116526849A CN116526849A CN202210062957.3A CN202210062957A CN116526849A CN 116526849 A CN116526849 A CN 116526849A CN 202210062957 A CN202210062957 A CN 202210062957A CN 116526849 A CN116526849 A CN 116526849A
- Authority
- CN
- China
- Prior art keywords
- switch
- capacitor
- self
- transformer
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 58
- 238000006243 chemical reaction Methods 0.000 claims abstract description 31
- 238000004804 winding Methods 0.000 claims abstract description 31
- 230000005669 field effect Effects 0.000 claims description 5
- 229910044991 metal oxide Inorganic materials 0.000 claims description 4
- 150000004706 metal oxides Chemical class 0.000 claims description 4
- 239000004065 semiconductor Substances 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 10
- 239000008186 active pharmaceutical agent Substances 0.000 description 8
- 230000003071 parasitic effect Effects 0.000 description 7
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention is a self-excited active clamping circuit, applied to the primary side of the transformer of a flyback power conversion device under a current critical mode (BCM), the self-excited active clamping circuit includes a clamping switch, connect in series between a first capacitor and a second capacitor, the other end of the first capacitor connects the primary side winding of the transformer of the power conversion device, the other end of the second capacitor connects the change-over switch of the power conversion device, a control end of the clamping switch connects the change-over switch through a resistor; therefore, the invention can automatically determine the on/off state of the clamping switch according to the voltage polarity of the primary winding of the transformer, the first capacitor and the second capacitor not only can absorb the surge, but also can lead the gate electrode of the clamping switch to obtain ideal driving voltage, and the clamping switch has smaller on-resistance when being conducted so as to reduce the loss.
Description
Technical Field
The present invention relates to a self-excited active clamp circuit (self-driven active clamp), and more particularly to an active clamp circuit applied to a flyback power conversion device in a current critical mode (BCM).
Background
Among various power conversion devices, a flyback power conversion device is a relatively common device that can be used for ac-dc conversion or dc-dc conversion. The flyback power conversion device has the advantage of circuit isolation because the flyback power conversion device uses a transformer between the input and the output. The flyback power conversion device can be further divided into a general flyback power conversion device (Standard flyback converter) and an active clamping flyback (Active Clamp Flyback, ACF) power conversion device.
In the active clamping flyback power conversion device, a clamping switch (clamp switch) formed by a field effect transistor (MOSFET) is used on the primary side of a transformer to replace a buffer (Snubber) diode in a general flyback power conversion device, so that the purposes of absorbing the surge, recovering the energy and improving the conversion efficiency are achieved.
If the on/off of the clamp switch is controlled by using a separate driving circuit, the complexity of the circuit is increased due to the additional driving circuit and the power circuit required for controlling the same, and the size of the power conversion device is not reduced. In addition, when the clamp switch is controlled, how to properly drive the clamp switch is also needed to prevent the conduction loss and the switching loss of the clamp switch from being too high to affect the conversion efficiency of the whole power conversion device.
Disclosure of Invention
Accordingly, the present invention provides a self-excited active clamp circuit, which is applied to a flyback power conversion device, and can control the on/off operation of one clamp switch without adding an additional driving circuit, and make the clamp switch have lower on-loss when being turned on and achieve zero-voltage switching of the clamp switch, thereby reducing switching loss.
The invention relates to a self-excited active clamp circuit, which is mainly applied to a flyback power conversion device, wherein the power conversion device is provided with a transformer and a change-over switch, and the self-excited active clamp circuit comprises:
the clamping switch is connected in series between a first capacitor and a second capacitor, wherein the other end of the first capacitor is connected with the first end of the primary side winding of the transformer, and the other end of the second capacitor is connected with the second end of the primary side winding of the transformer and the switch;
one end of the resistor is connected with a control end of the clamping switch, and the other end of the resistor is connected with the second end of the primary winding of the transformer and the change-over switch.
Preferably, the self-excited active clamp circuit of the present invention further comprises a diode, wherein the anode of the diode is connected to the control end of the clamp switch, and the cathode of the diode is connected to the second end of the primary winding of the transformer and the switch.
Preferably, the clamp switch is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), the gate of which is the control terminal, the drain of which is connected to the first capacitor, and the source of which is connected to the second capacitor.
The self-excited active clamping circuit can control the on/off of the clamping switch according to the voltage VP polarity of the primary winding of the transformer, wherein the first capacitor and the second capacitor not only can achieve the function of absorbing the surge, but also can enable the gate electrode of the clamping switch to obtain an ideal driving voltage by properly selecting the size of the second capacitor, and the clamping switch has smaller on-resistance when being conducted so as to reduce the loss.
Drawings
Fig. 1: the self-excited active clamping circuit is applied to a circuit diagram of a flyback power supply conversion device.
Fig. 2A: output voltage V in FIG. 1 O Is a waveform diagram of (a).
Fig. 2B: the voltage V across the second capacitor (C2) in FIG. 1 C2 Waveform diagram.
Fig. 2C: the voltage V across the first capacitor (C1) in FIG. 1 C1 Waveform diagram.
Fig. 2D: the clamp switch (Q2) of FIG. 1 has a voltage V between drain and source Q2-DS Waveform diagram.
Fig. 2E: the clamp switch (Q2) of FIG. 1 has a gate-source voltage V Q2-G Waveform diagram.
Fig. 2F: in FIG. 1, the switch (Q1) has a voltage V between drain and source Q1-DS Waveform diagram.
Fig. 2G: in FIG. 1, the voltage V at the gate of the switch (Q1) is shown Q1-G Waveform diagram.
Fig. 2H: the primary winding of the transformer in fig. 1Voltage V between two ends of group P Waveform diagram.
Fig. 3: in fig. 1, the circuit operation is shown when the change-over switch (Q1) is turned off and the clamp switch (Q2) is turned on.
Fig. 4: in fig. 1, the circuit operation is shown when the change-over switch (Q1) is turned on and the clamp switch (Q2) is turned off.
10 self-excitation type active clamping circuit
20 transformer
21 primary side winding
22 secondary side winding
30 output circuit
31,32 output terminals
40:PWM controller
Vin input power supply
Q1 switch
Q2 clamping switch
C1 first capacitor
C2 second capacitor
C3 parasitic capacitance
D diode
R is resistance
Detailed Description
The technical means adopted by the invention to achieve the preset aim are further described below by matching with the drawings and the preferred embodiments of the invention.
The self-excited active clamp circuit is applied to the flyback power conversion device, wherein the whole circuit structure of the flyback power conversion device is shown in fig. 1, but the working principle of the flyback power conversion device is not the characteristic of the invention, so the power conversion operation of the flyback power conversion device is only schematically described.
First, the basic components of the flyback power converter include a transformer 20, a switch Q1, and an output circuit 30. The primary winding 21 of the transformer 20 is connected in series with the switch Q1, the switch Q1 may be formed by a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), the gate thereof is connected to a PWM controller 40, the PWM controller 40 outputs a PWM signal to control the on/off of the switch Q1, the drain of the switch Q1 is connected to the primary winding 21, and the source is grounded. One end of the primary winding 21 of the transformer 20 is connected to an input power source Vin, which is illustrated here as a dc power source.
The output circuit 30 is connected to the secondary winding 22 of the transformer 20 and includes two output terminals 31 and 32 for connecting a load, wherein the primary winding 21 and the secondary winding 22 of the transformer 20 are not commonly grounded.
The self-excited active clamp circuit 10 of the present invention is connected to the transformer 20 and the switch Q1, and includes a clamp switch Q2, a first capacitor C1, a second capacitor C2, a resistor R, and a diode D. One end of the clamp switch Q2 is connected to the first capacitor C1, and the other end is connected to the second capacitor C2, so that the clamp switch Q2 is connected in series between the first capacitor C1 and the second capacitor C2; a control terminal of the clamp switch Q2 is connected to the resistor R and the diode D.
In this embodiment, the clamp switch Q2 is formed of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). A parasitic capacitor C3 is provided between the gate and the source, the gate is used as the control terminal, and the drain and the source are respectively connected with the first capacitor C1 and the second capacitor C2.
One end of the first capacitor C1 is connected to the primary winding 21 of the transformer 20 and the input power Vin, and the other end is connected to the drain of the clamp switch Q2.
One end of the second capacitor C2 is connected with the source electrode of the clamping switch Q2, and the other end is connected with the drain electrode of the switching switch Q1.
The positive pole of the diode D is connected with the gate of the clamping switch Q2, the negative pole is also connected with the drain of the switching switch Q1, and the resistor R is connected across the two ends of the diode D.
Referring to the voltage waveforms shown in fig. 2A to 2G, the vertical axis of each waveform indicates a voltage value (V), and the horizontal axis indicates time; the circuit operation mode of the present invention is further described below.
t0 period: in BCM mode, the voltage V of the primary winding 21 of the transformer 20 P Gradually decrease to 0V, and the voltage V across the second capacitor C2 C2 Also down to 0V, parasitic capacitance C3The voltage is rapidly discharged to 0V through the diode D, so that the gate voltage of the clamp switch Q2 is lower than the conduction threshold voltage (Vgs-th), the clamp switch Q2 is turned to the off state, and at this time, the drain-source voltage V of the switch Q1 is switched Q1-DS The gate voltage V of the switch Q1 is changed over from the original high level to 0V along with Vp Q1-G A high level signal is started to be sent, and the control mode of the switch Q1 also reaches Zero Voltage Switching (ZVS).
t1 period: the switch Q1 is turned ON, and the switch Q1 is switched from the OFF (OFF) state to the ON (ON) state, and the voltage Vp of the primary winding 21 increases from 0V to Vin.
t2 period: when the gate voltage V of the switch Q1 is changed Q1-G When the voltage drops to a low level (i.e., a low level of the PWM signal), the switch Q1 is turned off. Since the switch Q1 is turned from the on state to the off state, a reverse voltage is generated in the primary winding 21 of the transformer 20, and the primary winding voltage V shown in FIG. 2H P Negative values are displayed. As shown in FIG. 3, the voltage V P Charging the second capacitor C2 and the first capacitor C1 via a body diode (body diode) of the clamp switch Q2, wherein the second capacitor C2 and the first capacitor C1 charge during charging and absorb a surge (spike) generated by leakage inductance of the transformer 20, and the second capacitor C2 and the first capacitor C1 charge gradually to a steady state at this time, the drain-source voltage V of the clamp switch Q2 Q2-DS Also, because the body diode is turned on first, the forward Voltage (VF) of the body diode is reduced to approximately the same value as the S position on the waveform diagram before the driving signal is applied. The second capacitor C2 charges the parasitic capacitor C3 through the resistor R during the charging process, and when the voltage of the parasitic capacitor C3 reaches the conducting threshold voltage (Vgs-th) of the clamp switch Q2, the clamp switch Q2 is turned to the conducting state, so as to realize Zero Voltage Switching (ZVS) and absorb the surge. Resistor R is used as a delay element, and the gate voltage V of clamp switch Q2 is enabled by the delay time determined by resistor R and parasitic capacitor C3 during charging Q2-G At the drain-source voltage V of the clamp switch Q2 Q2-DS The conduction is achieved when the forward Voltage (VF) of the body diode is reduced to aboutThe drive control of the clamp switch Q2 can be made to meet the zero voltage switching requirement by the threshold voltage (Vgs-th).
t3 period: in BCM mode, the voltage V of the primary winding 21 of the transformer 20 P Will gradually decrease to zero, the voltage V across the second capacitor C2 C2 Also reduce to 0V, the parasitic capacitor C3 discharges rapidly to 0V via diode D to make the gate voltage of the clamp switch Q2 lower than the on threshold voltage (Vgs-th), the clamp switch Q2 is turned off, since the clamp switch Q2 can be turned off rapidly, the switching loss of the clamp switch Q2 can be reduced, and the drain-source voltage V of the switch Q1 is changed Q1-DS The original high level is gradually reduced to 0V, and the operation of t0 period is repeated.
t4 period: at this time, the changeover switch Q1 is turned on, and as shown in fig. 4, the operation in the period t1 is repeated.
In a preferred embodiment, to turn on the clamp switch Q2, the on-resistance (R DS ) Minimum loss, the gate of the clamp switch Q2 should be maintained at a relatively ideal drive voltage value, on the order of about 10V. Typically, the sum (V) of the voltages of the first capacitor C1 and the second capacitor C2 C1 +V C2 ) About equal to the voltage of the primary winding 21 at the time of energy release (i.e. V P Reverse voltage), at this time V P Voltage value and number of turns N of primary winding 21 of transformer 20 P Turns N of secondary winding 22 S Related, i.e. V P ＝[(N S /N P )×V O ]. In practical design of the power conversion device, the V is due to different input/output requirements P The reverse voltage is limited by the turn ratio and cannot approach the preferred value of 10V, and the invention can select a proper value of the second capacitor C2, so that after the first capacitor C1 and the second capacitor C2 are divided, a voltage approaching 10V is obtained on the second capacitor C2, and the gate electrode of the clamping switch Q2 can have a preferred driving voltage value, thereby achieving a more ideal driving effect.
In summary, the self-excited active clamp circuit of the present invention does not need to additionally provide a driving circuit, and can be used for controlling the voltage V of the primary winding P The polarity itself controls the on/off of the clamp switch Q2. The self-excited active clampThe circuit not only can absorb the surge, but also can obtain an ideal driving voltage at the gate of the clamp switch Q2 by properly selecting the second capacitor C2, and the clamp switch Q2 has smaller on-resistance (R DS ) And the loss is reduced.
The present invention is not limited to the above-mentioned embodiments, but is not limited to the above-mentioned embodiments, and any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical matters of the present invention can be made by those skilled in the art without departing from the scope of the present invention.
Claims (5)
1. The utility model provides a self-excited active clamp circuit, is applied to a flyback power conversion device, characterized in that, this power conversion device has a transformer and a change over switch, and this self-excited active clamp circuit includes:
the clamping switch is connected in series between a first capacitor and a second capacitor, wherein the other end of the first capacitor is connected with the first end of the primary side winding of the transformer, and the other end of the second capacitor is connected with the second end of the primary side winding of the transformer and the switch;
one end of the resistor is connected with a control end of the clamping switch, and the other end of the resistor is connected with the second end of the primary winding of the transformer and the change-over switch.
2. The self-excited active clamp circuit of claim 1, wherein the self-excited active clamp circuit further comprises:
and the anode of the diode is connected with the control end of the clamping switch, and the cathode of the diode is connected with the second end of the primary side winding of the transformer and the change-over switch.
3. A self-excited active clamp circuit according to claim 1 or 2, wherein the clamp switch is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), the gate of which is the control terminal, the drain of which is connected to the first capacitor, and the source of which is connected to the second capacitor.
4. A self-excited active clamp circuit as claimed in claim 3, wherein the gate voltage of the clamp switch is raised to turn on the clamp switch when the voltage drop between the drain and source of the clamp switch is 0V, causing the clamp switch to operate at Zero Voltage Switching (ZVS).
5. A self-excited active clamp circuit as claimed in claim 4, wherein when the clamp switch is turned on, the primary winding of the transformer generates a reverse voltage, the reverse voltage charging the first capacitor and the second capacitor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210062957.3A CN116526849A (en) | 2022-01-20 | 2022-01-20 | Self-excited active clamping circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210062957.3A CN116526849A (en) | 2022-01-20 | 2022-01-20 | Self-excited active clamping circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116526849A true CN116526849A (en) | 2023-08-01 |
Family
ID=87396295
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210062957.3A Pending CN116526849A (en) | 2022-01-20 | 2022-01-20 | Self-excited active clamping circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116526849A (en) |
-
2022
- 2022-01-20 CN CN202210062957.3A patent/CN116526849A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP1159781B1 (en) | General self-driven synchronous rectification scheme for synchronous rectifiers having a floating gate | |
| US6473317B1 (en) | Forward DC/DC converter with semi-synchronous rectification and improved efficiency | |
| US20090059622A1 (en) | Bi-directional dc-dc converter and method for controlling the same | |
| US6839246B1 (en) | Self-driving circuit for a DC/DC converter | |
| CN110868073B (en) | Series connection SiC MOSFET drive circuit based on multi-winding transformer coupling | |
| CN103424602B (en) | Based on the secondary winding current testing circuit of source drive | |
| EP3509203B1 (en) | Converter with zvs | |
| US6353543B2 (en) | Switching circuit of power conversion apparatus | |
| CN108448902A (en) | A kind of synchronous rectification inverse-excitation type DC-DC power conversion equipment and control method | |
| CN109980903B (en) | Drive circuit and power supply | |
| CN110190732B (en) | Power supply and drive circuit of drive chip | |
| CN108667304A (en) | Synchronous rectification inverse-excitation type DC-DC power conversion equipment and control method | |
| CN208158436U (en) | A kind of synchronous rectification inverse-excitation type DC-DC power conversion equipment | |
| TWI762412B (en) | Totem-pole pfc circuit | |
| JP3644014B2 (en) | Synchronous rectifier circuit | |
| US8022665B2 (en) | Bidirectional power converting device | |
| US11973419B2 (en) | Inverter circuit and method, for example for use in power factor correction | |
| CN218733846U (en) | Double-tube flyback conversion circuit | |
| CN216794868U (en) | Self-excited active clamping circuit | |
| CN116526849A (en) | Self-excited active clamping circuit | |
| KR102142630B1 (en) | Driving circuit of voltage driven synchronous rectifier | |
| TWM628149U (en) | DC-DC power conversion circuit allowing multi-mode hybrid control | |
| US11936287B2 (en) | Self-driven active clamp circuit | |
| EP4243262A1 (en) | Self-driven active clamp circuit | |
| CN108599573B (en) | A kind of normal shock active clamp driving circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |