CN108667304B - Synchronous rectification flyback DC-DC power supply conversion device and control method - Google Patents

Synchronous rectification flyback DC-DC power supply conversion device and control method Download PDF

Info

Publication number
CN108667304B
CN108667304B CN201810360716.0A CN201810360716A CN108667304B CN 108667304 B CN108667304 B CN 108667304B CN 201810360716 A CN201810360716 A CN 201810360716A CN 108667304 B CN108667304 B CN 108667304B
Authority
CN
China
Prior art keywords
synchronous rectification
transformer
power
tube
flyback
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.)
Active
Application number
CN201810360716.0A
Other languages
Chinese (zh)
Other versions
CN108667304A (en
Inventor
谢小高
王奇钢
董汉菁
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hangzhou Dianzi University
Original Assignee
Hangzhou Dianzi University
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hangzhou Dianzi University filed Critical Hangzhou Dianzi University
Priority to CN201810360716.0A priority Critical patent/CN108667304B/en
Publication of CN108667304A publication Critical patent/CN108667304A/en
Application granted granted Critical
Publication of CN108667304B publication Critical patent/CN108667304B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

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
    • 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
    • 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)
  • Rectifiers (AREA)

Abstract

The invention discloses a synchronous rectification flyback DC-DC power supply conversion device and an implementation method thereof, wherein the device comprises a flyback circuit and an auxiliary switch; the flyback circuit comprises an input port, an output circuit and a transformer; the input port receives direct-current input voltage and supplies power to the transformer, and the primary side power switching tube is connected with the primary side power winding of the transformer in series; the output circuit is coupled with the secondary power winding of the transformer, and generates a direct current at the output port by the energy released by the transformer during the turn-off period of the primary power switching tube and provides the direct current for a load; the auxiliary switch is connected in parallel with the primary winding of the transformer; the invention connects an auxiliary switch in parallel at two ends of the primary winding of the transformer, namely, the synchronous rectification flyback DC-DC converter which has no common risk and is compatible with a current discontinuous mode, a current critical discontinuous mode and a current continuous mode can be realized by utilizing the secondary synchronous rectification control technology in the prior art.

Description

Synchronous rectification flyback DC-DC power supply conversion device and control method
Technical Field
The invention relates to a direct current-direct current power supply conversion device, in particular to a flyback direct current-direct current power supply conversion device with synchronous rectification, which is suitable for various working modes such as continuous current, intermittent current or critical intermittent current.
Background
Dc/dc conversion is one of the most basic forms of electrical energy conversion. The flyback converter is widely used in a low-power switching power supply due to the characteristics of simple topology, few components and the like, and is generally below 100-200W. The loss of the flyback converter mainly comprises the loss of a primary side switching tube, the loss of a transformer, the loss of an absorption circuit and the loss of a secondary side rectifier. The loss of the output end rectifier is one of the main losses of the flyback converter, and the loss of the rectifier tube accounts for a prominent proportion under the output condition of low voltage and large current.
One of the main approaches to reducing the loss of the rectifier tube is the synchronous rectification technique. Fig. 1 is a simplified schematic diagram of a flyback dc-dc power converter using synchronous rectification, wherein the synchronous rectification control circuit 100 is a prior art synchronous rectification control circuit.
As shown in FIG. 1, when the primary power switch Q1 is turned off, energy is transferred from the primary side of the transformer T to the secondary side, and the synchronous rectifier QSRDiode-connected freewheeling synchronous rectifier QSRBecomes negativeAnd (6) pressing. When VD voltage is lower than reference voltage VTH1, comparator 101 output is reversed to set trigger 103, output of trigger 103 is driven by drive circuit 104 to output control signal Vg _ SR of synchronous rectifier tube to control Q of synchronous rectifier tubeSRAnd conducting. Synchronous rectifier tube QSRThe conduction can greatly reduce the conduction voltage drop of the output rectifier, and the purposes of reducing loss and improving efficiency are achieved. When the VD voltage is higher than the reference voltage VTH2, the output of the comparator 102 is inverted, the trigger 103 is reset, and the synchronous rectifier Q2 is controlled to be turned off. In addition, a minimum on-time circuit 107 and an OR gate 108 are added to the synchronous rectification control circuit 100 to prevent the oscillation of VD waveform from causing the synchronous rectification tube QSRThe control signal Vg _ SR is turned off by mistake when being turned on, and a minimum turn-off time circuit 105 and an AND gate 106 are additionally added to set a minimum turn-off time so as to avoid a synchronous rectifier tube QSRAnd re-turned on after being turned off.
With the synchronous rectification control scheme shown in fig. 1, since VD is detected from the synchronous rectification control circuit 100 to reach the reference voltage until the synchronous rectification control signal flips, there is an inevitable delay in the control circuit, including the turn-on delay Td1 and the turn-off delay Td2 of the synchronous rectification transistor, as shown in fig. 2 and 3. Fig. 2 shows main waveforms of the flyback converter shown in fig. 1 when operating in the current discontinuous mode or the critical discontinuous mode, and fig. 3 shows main waveforms of the flyback converter shown in fig. 1 when operating in the current continuous mode.
As can be seen from FIG. 2, when the VD voltage reaches the reference VTH2, the synchronous rectification tube Q is delayed by a time delay Td2SRThe control signal Vg _ SR is inverted from high level to low level, and the synchronous rectifier tube QSRAnd is turned off, and the body diode thereof flows a secondary side current. Because the secondary side current falling gradient is smaller when the flyback converter works in the current discontinuous mode or the critical discontinuous mode, the synchronous rectifier tube QSRCan be controlled before the zero crossing of the secondary side current, so that the synchronous rectifier tube Q can not occurSRAnd the primary side power switch tube Q1.
As shown in FIG. 3, in the current continuous mode, the primary power is at time t3The switching tube Q1 is turned on and flows through the synchronous rectifier tube QSRThe current starts to rapidly drop with a larger slope, and the corresponding VD voltage starts to rise; at time t4, VD reaches reference VTH2, and after a time delay Td2, the synchronous rectifier Q is at time t5SRIs turned off. Therefore, in the interval from t3 to t5, the primary side power switch tube Q1 and the synchronous rectifier tube QSRAll are in a common state, so that a large common current can be generated, the flyback converter works abnormally, and even the circuit is damaged.
Therefore, the conventional synchronous rectification control technology shown in fig. 1 is only suitable for the flyback converter to operate in the current discontinuous mode or the critical discontinuous mode, and has a large limitation. In many applications or operating conditions, it is desirable to design the flyback converter to enter a current continuous mode in order to optimize device efficiency.
For a flyback converter in a current continuous mode, an existing solution is to transmit a signal of a primary side switching tube to a secondary side of a transformer by using an optical coupler or a magnetic element, and then the signal is subjected to certain logic processing and used for controlling a secondary side synchronous rectifier tube. However, as the high-frequency pulse signal is transmitted, the optical coupler needs to adopt an expensive high-speed optical coupler, and the price of the magnetic element is higher, so that the method for transmitting the control signal of the synchronous rectifier tube in an isolating way is relatively less applied in the industry.
Disclosure of Invention
In order to solve the above problems, the present invention provides a novel synchronous rectification flyback dc-dc power conversion device and a control method thereof.
A synchronous rectification flyback DC-DC power conversion device comprises: a flyback circuit and an auxiliary switch; the flyback circuit comprises an input circuit, an output circuit and a transformer; the input circuit comprises a primary side power switch tube, the input circuit receives direct current input voltage and supplies power to the transformer, and the primary side power switch tube is connected with a primary side power winding of the transformer in series; the output circuit is coupled with the secondary power winding of the transformer, and the energy released by the transformer during the turn-off period of the primary power switching tube generates a direct current at the output port of the output circuit to be supplied to a load; the auxiliary switch is connected in parallel with a primary side power winding of the transformer;
preferably, the dc input voltage of the input circuit is a dc voltage directly output by a dc power supply such as a battery or a dc voltage output by another conversion circuit, and the dc input voltage is a constant dc voltage or a sinusoidal half-wave voltage output by an ac voltage of a power grid via a diode rectifier circuit.
Preferably, one end of a primary power winding of the transformer is connected with a direct-current input voltage anode, the other end of the primary power winding of the transformer is connected with a drain electrode of a primary power switching tube, a source electrode of a first switching tube is connected with a direct-current input voltage cathode, one end of a secondary power winding of the transformer is connected with a VD (voltage distribution) end of the synchronous rectification control circuit and a drain electrode of a secondary synchronous rectification tube, a grid electrode of the secondary synchronous rectification tube is connected with a VG end of the synchronous rectification control circuit, the other end of the secondary power winding of the transformer is connected with one end of a capacitor Co and one end of a load, and the other end of the capacitor Co is connected with the other end of the load, the source electrode of the secondary synchronous rectification; the auxiliary switch is connected in parallel with the primary power winding of the transformer.
Preferably, one end of a primary power winding of the transformer is connected with a source electrode of a primary power switching tube, a drain electrode of the primary power switching tube is connected with a direct current input voltage anode, the other end of the primary power winding of the transformer is connected with a direct current input voltage cathode, one end of a secondary power winding of the transformer is connected with a VD (voltage distribution) end of the synchronous rectification control circuit and a drain electrode of a secondary synchronous rectification tube, a grid electrode of the secondary synchronous rectification tube is connected with a VG (voltage distribution) end of the synchronous rectification control circuit, the other end of the secondary power winding of the transformer is connected with one end of a capacitor Co and one end of a load, and the other end of the capacitor Co is connected with the other end of the load, the source electrode of the secondary; the auxiliary switch is connected in parallel with the primary power winding of the transformer.
Preferably, the auxiliary switch is a semiconductor device having bidirectional blocking capability.
Preferably, the auxiliary switch is a composite switch formed by a diode and a metal oxide semiconductor field effect transistor, and the direction of the diode is opposite to that of the metal oxide semiconductor field effect transistor body diode;
preferably, the auxiliary switch is a composite switch formed by two metal oxide semiconductor field effect transistors connected in series in an opposite direction.
Preferably, the time for which the auxiliary switch is turned on is fixed or is adjusted by a control circuit of the synchronous rectification flyback dc-dc power conversion device according to the working condition of the circuit.
Preferably, the excitation current of the transformer operates in an intermittent state, a continuous state or a critical intermittent state.
A control method of a synchronous rectification flyback DC-DC power supply conversion device specifically comprises the following steps:
step 1: the synchronous rectification flyback DC-DC power supply conversion device respectively generates a control signal of a primary side power switch tube and a control signal of an auxiliary switch;
step 2: the auxiliary switch is conducted once or twice before the primary side power switch tube is switched on, so that the primary side power winding of the transformer is short-circuited in the period of time;
and step 3: the synchronous rectification control circuit generates a synchronous rectification tube control signal according to voltage signals at two ends of the secondary synchronous rectification tube.
Preferably, when the synchronous rectification flyback type direct current-direct current power supply conversion device works in a current continuous mode, the auxiliary switch is conducted once or twice before the primary side power switch tube is switched on; when the synchronous rectification flyback type direct current-direct current power supply conversion device works in a current discontinuous mode or a current critical discontinuous mode, the auxiliary switch is conducted once, twice or not before the primary side power switch tube is switched on.
The principle of the invention is as follows: for a synchronous rectification flyback type direct current-direct current converter, when the synchronous rectification flyback type direct current-direct current converter works in a current continuous state, because the secondary current is reduced after a primary power switch tube is switched on, the common problem exists in a conventional control mode of detecting that the negative voltage of the voltage at two ends of the secondary synchronous rectifier tube reaches the amplitude of a certain threshold value to switch off the synchronous rectifier tube. The synchronous rectification flyback type direct current-direct current power supply conversion device clamps all winding voltages of the transformer at a zero level by utilizing the auxiliary switch which is connected with the primary winding of the transformer in parallel to conduct for a period of time before the primary power switch tube is switched on, correspondingly enables the voltages at two ends of the secondary synchronous rectifier tube to be equal to the output voltage, and therefore the secondary synchronous rectifier tube is switched off before the primary power switch tube is switched on, and the possibility that the primary power switch tube and the secondary synchronous rectifier tube are in common is eliminated. When the synchronous rectification flyback type direct current-direct current converter works in a current discontinuous mode or a current critical discontinuous mode, the device and the method of the invention are still applicable because the conventional control mode for detecting the negative voltage at two ends of the secondary synchronous rectifier tube can turn off the secondary synchronous rectifier tube in advance before the primary power switch tube is turned on.
Compared with the prior art, the circuit structure and the implementation method thereof adopted by the invention have obvious advantages; only one auxiliary switch is connected in parallel at two ends of a primary power winding of the transformer, namely, a synchronous rectification flyback type direct current-direct current converter which is free of common risks and compatible with a current intermittent mode, a current critical intermittent mode and a current continuous mode can be realized by utilizing a secondary synchronous rectification control technology in the prior art, and a driving signal generation logic circuit of the auxiliary switch is simple. Furthermore, a driving signal generating circuit of the auxiliary switch and a control circuit of the conventional flyback converter can be integrated into the same chip, so that the cost of the device is further reduced.
Drawings
FIG. 1 illustrates a synchronous rectified flyback DC-DC converter employing a prior art synchronous rectified control circuit;
FIG. 2 illustrates key waveforms for the circuit of FIG. 1 operating in a current chopping mode;
FIG. 3 shows key waveforms for the circuit of FIG. 1 operating in current continuous mode;
FIG. 4 is a schematic diagram of a first embodiment of the synchronous rectification flyback DC-DC converter according to the present invention;
fig. 5 shows specific waveforms of a first specific embodiment of the synchronous rectification flyback dc-dc converter according to the present invention operating in a current continuous mode by using a first auxiliary switch control manner;
fig. 6 shows specific waveforms of a first specific embodiment of the synchronous rectification flyback dc-dc converter according to the present invention, which operates in a current interruption mode by using a first auxiliary switch control manner;
fig. 7 shows specific waveforms of the first specific embodiment of the synchronous rectification flyback dc-dc converter of the present invention operating in the current continuous mode by using the second auxiliary switch control manner;
fig. 8 shows specific waveforms of the first specific embodiment of the synchronous rectification flyback dc-dc converter of the present invention operating in the current continuous mode by using the third auxiliary switch control manner;
fig. 9 is a schematic diagram of a second embodiment of the synchronous rectification flyback dc-dc converter of the present invention;
fig. 10 shows a specific embodiment of the auxiliary switch of the synchronous rectification flyback dc-dc converter of the present invention.
Detailed Description
The present invention is described in detail below with reference to the attached drawings. The features and details of the present invention may be more readily understood through the description of the specific embodiments of the invention. Well-known embodiments and operating means have not been described in detail herein in order not to obscure the various technical embodiments of the invention, but it will be apparent to those skilled in the art that one or more of the specific details or components are missing without affecting the understanding and implementation of the invention.
Reference throughout this specification to "an embodiment" or "one embodiment" means that a particular feature, structure, implementation, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrase "in one embodiment" in various places throughout the specification are not necessarily all referring to the same embodiment. The features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
Fig. 4 is a circuit diagram of a first embodiment of the synchronous rectification flyback dc-dc converter according to the present invention, which includes a flyback circuit 200 and an auxiliary switch Qa, and further includes a synchronous rectification control circuit 100.
Wherein, the flyback circuit 200 includes:
the input circuit comprises a primary side power switch tube Q1 and receives a direct current input voltage Vin; the two input ends of the input circuit are respectively connected with the dotted terminal of the primary power winding Wp of the transformer T and the source electrode of the primary power tube Q1, the dotted terminal of the primary power winding Wp of the transformer T is connected with the positive terminal of the direct current input voltage Vin, the source electrode of the primary power tube Q1 is connected with the negative terminal of the direct current input voltage Vin, the drain electrode of the primary power switch tube Q1 is connected with the synonym terminal of the primary power winding Wp of the transformer T, and the grid electrode of the primary power switch tube Q1 receives a control signal Vg 1;
the transformer T at least comprises a primary side power winding Wp and a secondary side power winding Ws;
an output circuit including a secondary synchronous rectifier QSRThe synonym of the secondary power winding Ws of the transformer T is connected with the anode of the output capacitor Co, the synonym of the secondary power winding Ws of the transformer T is connected with the secondary synchronous rectifier tube QSRThe secondary side synchronous rectifier tube QSRThe source of the secondary side synchronous rectifier tube Q is connected with the cathode of the output capacitor CoSRReceives the control signal Vg _ SR.
The auxiliary switch Qa is connected in parallel with the primary winding Wp of the transformer T, one end of the auxiliary switch Qa is connected with the dotted end of the primary winding Wp of the transformer T, the other end of the auxiliary switch Qa is connected with the synonym end of the primary winding Wp of the transformer T, and the control end of the auxiliary switch Qa receives the control signal Vga.
The drain electrode of the VD end secondary synchronous rectifier tube QSR of the synchronous rectification control circuit 100, the GND end of the drain electrode, and the VG end of the gate electrode are connected with the source electrode and the gate electrode of the secondary synchronous rectifier tube QSR.
For convenience of description, the turn ratio n of the transformer T is defined as the ratio of the number of turns of the primary power winding Wp to the number of turns of the secondary power winding Ws, which is the same in other embodiments of the present specification and is not separately defined.
Referring to fig. 5, a first embodiment of a synchronous rectification flyback dc-dc converter of the present invention employs specific waveforms of a first auxiliary switch control mode operating in a current continuous mode and the prior art synchronous rectification control circuit 100 shown in fig. 1:
at time T1, the primary power switch Q1 Is turned off, the energy stored in the transformer T Is transferred to the output loop, the primary current Ip decreases, the secondary current Is increases, and the secondary synchronous rectifier QSRThe body diode of the rectifier conducts the secondary side current Is to make the secondary side synchronous rectifier QSRThe voltage across Vds _ QSR is equal to the voltage drop of the negative body diode. According to the operation principle of the synchronous rectification control circuit 100 shown in fig. 1, the secondary side synchronous rectification tube QSRThe body diode is reduced to be lower than the internal reference voltage VTH1 of the synchronous rectification control circuit 100, the output of the comparator 101 is inverted, the trigger 103 is set, the output of the trigger 103 is transmitted to the secondary side synchronous rectification tube Q through the drive circuit 104SRA gate electrode of (1). At time t2 after considering the delay Td1 generated by the logic circuit in the synchronous rectification control circuit 100, the control signal Vg _ SR of the secondary synchronous rectification tube is inverted from low level to high level to control the secondary synchronous rectification tube QSRAnd conducting. In the secondary side synchronous rectifier QSRDuring the conduction period, the secondary synchronous rectifier Q Is reduced along with the reduction of the secondary current IsSRThe voltage Vds _ SR across rises, but since the circuit operates in a current continuous state, Vds _ SR does not reach the reference voltage VTH 2;
at time T3, the control signal Vga of the auxiliary switch Qa is at high level, the auxiliary switch Qa is controlled to be on, the primary winding Wp of the transformer T is short-circuited by Qa, the voltage across the secondary power winding Ws of the transformer T is zero or nearly zero due to the mutual coupling of the windings of the transformer T, and the secondary synchronous rectifier QSRThe voltage Vds _ SR rises to be higher than the reference voltage VTH2, the output of the comparator 102 is inverted to reset the flip-flop 103, and the output of the flip-flop 103 is transmitted to the secondary synchronous rectifier Q through the driving circuit 104SRThe gate electrode of (a) the gate electrode,the secondary current Is begins to decrease and the current in the primary power winding loop increases. At time t4 after considering the delay Td2 generated by the internal logic circuit of the synchronous rectification control circuit 100, the control signal Vg _ SR of the secondary synchronous rectification tube is inverted from high level to low level to control the secondary synchronous rectification tube QSRTurning off the secondary side current Is, returning the secondary side current Is to zero, and then forming a circulation loop by the residual energy in the primary side winding Wp of the transformer T through the auxiliary switch Qa;
at time T5, the control signal Vga of the auxiliary switch Qa is inverted from high level to low level, the auxiliary switch Qa is turned off, and the short-circuit effect of each winding of the transformer T is removed; meanwhile, a grid signal of the primary side power switch tube Q1 is inverted from a low level to a high level, the primary side power switch tube Q1 is conducted, and energy stored in the primary side winding Wp enables the primary side current Ip to generate a certain initial value; during the conduction period of the primary power switch tube Q1, a dc input voltage V1 is applied across the primary power winding Wp of the transformer T to excite the excitation inductor of the transformer T, and the primary current Ip begins to rise.
As can be seen from the above analysis, in the current continuous mode, the synchronous rectification flyback dc-dc power conversion device provided by the present invention turns off the secondary synchronous rectifier in advance before the primary power switching tube is turned on, so as to eliminate the possibility of the primary power switching tube and the secondary synchronous rectifier being in common, the primary side of the transformer does not generate common current, but the delay Td2 of the synchronous rectification control circuit 100 causes the secondary synchronous rectifier QSRThe auxiliary switch Qa and the auxiliary switch Qa have a common period Td2, during which the secondary side current Is of the transformer may decrease to a negative value, thereby increasing the circuit loss. Compared with the traditional synchronous rectification flyback DC-DC power supply conversion device, the primary side power switching tube and the secondary side synchronous rectification tube are not shared, so that the circuit loss is greatly reduced, and the risk of component damage is avoided.
Referring to fig. 6, the first embodiment of the synchronous rectification flyback dc-dc converter of the present invention employs specific waveforms of a first auxiliary switch control mode operating in a current interruption mode and the prior art synchronous rectification control circuit 100 shown in fig. 1:
at time T1, the primary power switch Q1 Is turned off, the energy stored in the transformer T Is transferred to the output loop, the primary current Ip decreases, the secondary current Is increases, and the secondary synchronous rectifier QSRThe body diode of the rectifier conducts the secondary side current Is to make the secondary side synchronous rectifier QSRThe voltage across Vds _ QSR is equal to the voltage drop of the negative body diode. According to the operation principle of the synchronous rectification control circuit 100 shown in fig. 1, the secondary side synchronous rectification tube QSRThe body diode is reduced to be lower than the internal reference voltage VTH1 of the synchronous rectification control circuit 100, the output of the comparator 101 is inverted, the trigger 103 is set, the output of the trigger 103 is transmitted to the secondary side synchronous rectification tube Q through the drive circuit 104SRA gate electrode of (1). At time t2 after the delay time Td1 generated by the internal logic circuit of the synchronous rectification control circuit 100 is considered, the control signal Vg _ SR of the secondary synchronous rectification tube is inverted from low level to high level to control the secondary synchronous rectification tube QSRConducting;
in the secondary side synchronous rectifier QSROn, as the secondary current Is decreases, the secondary synchronous rectifier QSRThe voltage Vds _ SR across rises. At time t3, Vds _ SR reaches the reference voltage VTH2, the output of the comparator 102 flips to reset the flip-flop 103, and the output of the flip-flop 103 is sent to the secondary synchronous rectifier Q through the driving circuit 104SRA gate electrode of (1). At time t4 after considering the delay Td2 generated by the logic circuit in the synchronous rectification control circuit 100, the control signal Vg _ SR of the secondary synchronous rectifier is inverted from high level to low level to control the secondary synchronous rectifier QSRTurn-off, secondary side synchronous rectifier QSRThe body diode of the diode Is conducted to flow a secondary side current Is;
at the time T5, the secondary side current Is reduced to zero, and the excitation inductance of the transformer T and the equivalent capacitance at the two ends of the primary side power switch tube Q1 oscillate;
at time T6, the control signal Vga of the auxiliary switch Qa is at high level, the auxiliary switch Qa is controlled to be on, the primary winding Wp of the transformer T is short-circuited by Qa, the voltage across the secondary power winding Ws of the transformer T is zero or nearly zero due to the mutual coupling of the windings of the transformer T, and the secondary synchronous rectifier QSRThe voltage Vds _ SR at both ends is equal toAt the output voltage Vo. Since the control signal Vg _ SR of the secondary synchronous rectifier has already been inverted to a low level at time t4, the action of the auxiliary switch Qa does not affect the state of Vg _ SR;
at the time T7, the control signal Vga of the auxiliary switch Qa is inverted from the high level to the low level, the short circuit effect of each winding of the transformer T is removed, at the time T7 or after a short time delay, the gate signal of the primary side power switch Q1 is inverted from the low level to the high level, the direct current input voltage V1 is added to the two ends of the primary side power winding Wp of the transformer T to excite the excitation inductor of the transformer T, and the primary side current Ip starts to rise from zero.
From the above analysis, it can be seen that in the current interruption mode, the auxiliary switch Qa is aligned with the secondary synchronous rectifier QSRHas no influence on the normal operation, so that the control signal of the auxiliary switch Qa can be selectively shielded in the current interruption mode, so that the auxiliary switch Qa does not operate.
Referring to fig. 7, the first embodiment of the synchronous rectification flyback dc-dc converter of the present invention adopts a specific waveform of the second auxiliary switch control mode operating in the current continuous mode and the prior art synchronous rectification control circuit 100 shown in fig. 1:
at time T3, the control signal Vga of the auxiliary switch Qa changes from low level to high level to control the auxiliary switch Qa to conduct, the primary power winding Wp of the transformer T Is short-circuited by Qa, because the windings of the transformer T are coupled to each other, the voltages at the two ends of the primary power winding Wp and the secondary power winding Ws of the transformer T are also zero or approximately zero, the secondary current Is begins to drop, and the secondary synchronous rectifier Q IsSRThe voltage Vds _ SR across begins to rise to be equal to the output voltage Vo and thus higher than the reference voltage VTH2, the output of the comparator 102 flips to reset the flip-flop 103, and the output of the flip-flop 103 is transmitted to the secondary synchronous rectifier Q via the driving circuit 104SRA gate electrode of (1). At time t4, the control signal Vga of the auxiliary switch Qa changes from high level to low level, the auxiliary switch Qa Is turned off, the short circuit effect of the auxiliary switch Is removed, the voltage across the primary side power switch Q1 rises, the secondary side current Is starts to rise, and the secondary side synchronous rectifier Q starts to riseSRAnd maintaining conduction. In view of synchronous rectification controlThe secondary synchronous rectifier Q at time t5 after a delay Td2 produced by the internal logic of the circuit 100SRThe control signal Vg _ SR is inverted from high level to low level to control the secondary side synchronous rectifier tube QSRTurn-off, secondary side synchronous rectifier QSRThe body diode of the rectifier passes a secondary side current Is and a secondary side synchronous rectifier QSRIs lower than the reference voltage VTH1, but due to the action of the minimum off-time block inside the synchronous rectification control circuit 100, the secondary side synchronous rectification QSRStill remaining off. At the time t6, the grid signal of the primary side power switch tube Q1 is inverted from low level to high level, the primary side power switch tube Q1 is conducted, and the energy of the secondary side is transferred to the primary side, so that the primary side current Ip generates a certain initial value; during the conduction period of the primary power switch tube Q1, a dc input voltage V1 is applied across the primary power winding Wp of the transformer T to excite the excitation inductor of the transformer T, and the primary current Ip begins to rise.
Similarly, the invention shown in fig. 7 operates in the current interruption mode by using the second auxiliary switch control mode, and the auxiliary switch Qa is applied to the secondary synchronous rectifier QSRHas no influence on the normal operation of the device, and is not analyzed in detail here.
Compared with the first auxiliary switch control mode adopted by the invention shown in fig. 5, the second auxiliary switch control mode adopted by the invention shown in fig. 7 has the advantages that the pulse width of the auxiliary switch Qa can be set to be smaller than the delay time Td2 of the synchronous rectification control circuit, so that the common conduction time of the secondary side and the primary side power winding loop of the transformer Is shorter, the negative value of the secondary side current Is also reduced, and the circuit loss Is reduced.
Referring to fig. 8, the first embodiment of the synchronous rectification flyback dc-dc converter of the present invention adopts a third auxiliary switch control mode to work in the current continuous mode with specific waveforms and the prior art synchronous rectification control circuit 100 shown in fig. 1:
at time T3, the control signal Vga of the auxiliary switch Qa changes from low level to high level to control the auxiliary switch Qa to be turned on, the primary power winding Wp of the transformer T is shorted by Qa, and the primary power of the transformer T is coupled to each otherThe voltage at the two ends of the winding Wp and the secondary power winding Ws Is also zero or approximately zero, the secondary current Is begins to decrease, and the secondary synchronous rectifier QSRThe voltage Vds _ SR across begins to rise to be equal to the output voltage Vo and thus higher than the reference voltage VTH2, the output of the comparator 102 flips to reset the flip-flop 103, and the output of the flip-flop 103 is transmitted to the secondary synchronous rectifier Q via the driving circuit 104SRA gate electrode of (1). At time t4, the control signal Vga of the auxiliary switch Qa changes from high level to low level, the auxiliary switch Qa Is turned off, the short circuit effect of the auxiliary switch Is removed, the voltage across the primary side power switch Q1 rises, the secondary side current Is starts to rise, and the secondary side synchronous rectifier Q starts to riseSRAnd maintaining conduction. At time t5 after considering the delay time Td2 generated by the internal logic circuit of the synchronous rectification control circuit 100, the secondary synchronous rectification tube QSRThe control signal Vg _ SR is inverted from high level to low level to control the secondary side synchronous rectifier tube QSRTurn-off, secondary side synchronous rectifier QSRThe body diode of the rectifier passes a secondary side current Is and a secondary side synchronous rectifier QSRIs lower than the reference voltage VTH1, but due to the action of the minimum off-time block inside the synchronous rectification control circuit 100, the secondary side synchronous rectification QSRStill remaining off. At the time T6, the control signal Vga of the auxiliary switch Qa changes from low level to high level again, the auxiliary switch Qa Is controlled to be turned on, the primary power winding Wp of the transformer T Is short-circuited by Qa, because the windings of the transformer T are coupled with each other, the voltages at the two ends of the primary power winding Wp and the secondary power winding Ws of the transformer T are also zero or approximately zero, the secondary current Is begins to drop, and the secondary synchronous rectifier Q IsSRThe voltage Vds _ SR across the primary power switch tube begins to rise to equal the output voltage Vo, and the voltage Vds _ Q1 across the primary power switch tube drops to equal the input voltage Vin. At the time t7, the grid signal of the primary side power switch tube Q1 is inverted from low level to high level, the primary side power switch tube Q1 is conducted, and the energy of the secondary side is transferred to the primary side, so that the primary side current Ip generates a certain initial value; during the conduction period of the primary power switch tube Q1, a dc input voltage V1 is applied across the primary power winding Wp of the transformer T to excite the excitation inductor of the transformer T, and the primary current Ip begins to rise.
LikeIn the invention shown in fig. 8, the third auxiliary switch control mode is adopted to operate in the current interruption mode, and the auxiliary switch Qa is used for the secondary side synchronous rectifier QSRHas no influence on the normal operation of the device, and is not analyzed in detail here.
Compared with the second auxiliary switch control mode adopted by the invention shown in fig. 7, the third auxiliary switch control mode adopted by the invention shown in fig. 8 is adopted, the auxiliary switch Qa is conducted twice before the primary side power switch tube is turned on, and during the second conduction period, the voltage Vds _ Q1 at the two ends of the primary side power switch tube Q1 is reduced to be equal to the input voltage Vin, so that the loss of the primary side power switch tube Q1 can be reduced when the primary side power switch tube Q1 is turned on.
Fig. 9 is a circuit diagram of a synchronous rectification flyback dc-dc converter according to a second embodiment of the present invention, where the synchronous rectification flyback dc-dc converter includes a flyback circuit 200 and an auxiliary switch Qa, and further includes a synchronous rectification control circuit 100.
Wherein, the flyback circuit 200 includes:
the input circuit comprises a primary side power tube Q1 and receives direct current input voltage; the two input ends of the input circuit are respectively the drain electrode of a primary power switch tube Q1 and the synonym end of a primary power winding Wp of a transformer T, the drain electrode of the primary power switch tube Q1 is connected with the positive end of a direct-current input voltage Vin, the source electrode of the primary power switch tube Q1 is connected with the synonym end of the primary power winding of the transformer T, and the grid electrode of the primary power switch tube Q1 receives a control signal Vg 1; the synonym end of a primary side power winding Wp of the transformer T is connected with the negative end of the direct-current input voltage Vin;
the transformer T at least comprises a primary side power winding Wp and a secondary side power winding Ws;
an output circuit including a secondary synchronous rectifier QSRThe synonym of the secondary power winding Ws of the transformer T is connected with the anode of the output capacitor Co, the synonym of the secondary power winding Ws of the transformer T is connected with the secondary synchronous rectifier tube QSRThe secondary side synchronous rectifier tube QSRIs connected with the negative electrode of the output capacitor CoA secondary side synchronous rectifier QSRReceives the control signal Vg _ SR.
The auxiliary switch Qa is connected in parallel with the primary winding Wp of the transformer T, one end of the auxiliary switch Qa is connected with the dotted end of the primary winding Wp of the transformer T, the other end of the auxiliary switch Qa is connected with the synonym end of the primary winding Wp of the transformer T, and the control end of the auxiliary switch Qa receives the control signal Vga.
The drain electrode of the VD end secondary synchronous rectifier tube QSR of the synchronous rectification control circuit 100, the GND end of the drain electrode, and the VG end of the gate electrode are connected with the source electrode and the gate electrode of the secondary synchronous rectifier tube QSR.
The second embodiment of the synchronous rectification flyback dc-dc converter shown in fig. 9 is different from the first embodiment of the synchronous rectification flyback dc-dc converter shown in fig. 4 only in that the structures of the flyback circuits are different, the working process is basically the same as the control method of the secondary synchronous rectifier, and details are not repeated here.
Further, it should be understood by those skilled in the art that when the synchronous rectification flyback dc-dc converter of the present invention operates in the current critical discontinuous mode, the turn-off process of the secondary synchronous rectifier is similar to that when the synchronous rectification flyback dc-dc converter operates in the current critical discontinuous mode, and the auxiliary switch has no influence, and therefore, it is not separately described.
Several embodiments of the auxiliary switch Qa in the present invention are shown with reference to fig. 10. The auxiliary switch Qa may be a single semiconductor device with bidirectional blocking capability, such as a bipolar transistor shown in fig. 10(a), an emitter of the bipolar transistor is connected to the dotted terminal of the primary winding Wp of the transformer T as an a terminal of the auxiliary switch Qa, a B terminal of the auxiliary collector switch Qa of the bipolar transistor is connected to the dotted terminal of the primary winding Wp of the transformer T, and a base of the bipolar transistor is used as a control terminal C of the auxiliary switch Qa to receive the control signal Vga.
The auxiliary switch Qa may be a composite switch including a plurality of semiconductor devices shown in fig. 10(b) to (e). Referring to fig. 10(b), the auxiliary switch Qa is a composite switch composed of two reverse-connected MOSFETs Qa1 and Qa 2. The source of the Qa1 is connected to the dotted terminal of the primary winding Wp of the transformer T as the a terminal of the auxiliary switch Qa, the drain thereof is connected to the drain of the Qa2, the source of the Qa2 is connected to the dotted terminal of the primary winding Wp of the transformer T as the B terminal of the auxiliary switch Qa, and the gates of the Qa1 and Qa2 are connected to each other as the control terminal C of the auxiliary switch Qa to receive the control signal Vga;
referring to fig. 10(c), the auxiliary switch Qa is a composite switch composed of two reverse series IGBTs Qa1 and Qa 2. Wherein, the emitter of Qa1 is connected to the dotted terminal of the primary winding Wp of the transformer T as the a terminal of the auxiliary switch Qa, the collector thereof is connected to the collector of Qa2, the emitter of Qa2 is connected to the synonym terminal of the primary winding Wp of the transformer T as the B terminal of the auxiliary switch Qa, the gates of Qa1 and Qa2 are connected to each other as the control terminal C of the auxiliary switch Qa to receive the control signal Vga;
referring to fig. 10(d), the auxiliary switch Qa is a composite switch composed of one MOSFET Qb and one diode Db. The source of Qb is used as the A end of the auxiliary switch Qa and is connected to the dotted end of the primary winding Wp of the transformer T, the grid of Qb is used as the control end C of the auxiliary switch Qa to receive the control signal Vga, the drain of Qb is connected with the cathode of Db, and the anode of Db is used as the B end of the auxiliary switch Qa and is connected to the dotted end of the primary winding Wp of the transformer T;
referring to fig. 10(e), the auxiliary switch Qa is a composite switch composed of one IGBT Qb and one diode Db. The emitter of Qb is used as the A end of the auxiliary switch Qa to connect to the dotted end of the primary winding Wp of the transformer T, the gate of Qb is used as the control end C of the auxiliary switch Qa to receive the control signal Vga, the collector of Qb is connected to the cathode of Db, and the anode of Db is used as the B end of the auxiliary switch Qa to connect to the dotted end of the primary winding Wp of the transformer T.
The above detailed description of embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
The teachings provided herein are not necessarily applicable to the above-described systems, but may be applicable to other systems as well. The elements and acts of the various embodiments described above can be combined to provide further embodiments.
While the present invention is susceptible to modification in light of the foregoing detailed description, the foregoing description describes specific embodiments of the invention and describes the best mode contemplated, it is possible to practice the invention in many ways, no matter how detailed the foregoing appears in text. The details of the above-described circuit configuration and manner of controlling the same may vary considerably in the details of its implementation, while still being encompassed by the invention disclosed herein.
As noted above, it should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to certain specific characteristics, features, or aspects of the invention with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification, unless the above detailed description section explicitly defines such terms. Accordingly, the actual scope of the invention encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the invention under the claims.
While certain aspects of the invention are described below in terms of certain specific claims, the inventors contemplate the various aspects of the invention in a number of claim forms. Accordingly, the inventors reserve the right to add additional claims after filing the application to pursue such additional aspects of the invention in the form of such additional claims.
The invention also provides a control method of the secondary side synchronous rectifier tube of the synchronous rectification flyback type direct current-direct current power supply conversion device, which is compatible with the current interrupted mode, the current critical interrupted mode and the current continuous mode, and comprises the following steps:
step 1: the synchronous rectification flyback DC-DC power supply conversion device respectively generates a control signal of a primary side power switch tube and a control signal of an auxiliary switch;
step 2: the auxiliary switch is conducted once or twice before the primary side power switch tube is switched on, so that the primary side power winding of the transformer is short-circuited during the conduction period of the auxiliary switch;
and step 3: the synchronous rectifier tube control circuit generates a synchronous rectifier tube control signal according to voltage signals at two ends of the secondary synchronous rectifier tube.

Claims (11)

1. Synchronous rectification flyback type direct current-direct current power supply conversion device is characterized in that: the method comprises the following steps: a flyback circuit and an auxiliary switch; the flyback circuit comprises an input circuit, an output circuit and a transformer; the input circuit comprises a primary side power switch tube, the input circuit receives direct current input voltage and supplies power to the transformer, and the primary side power switch tube is connected with a primary side power winding of the transformer in series; the output circuit is coupled with the secondary power winding of the transformer, and the energy released by the transformer during the turn-off period of the primary power switching tube generates a direct current at the output port of the output circuit to be supplied to a load; the auxiliary switch is connected in parallel with the primary power winding of the transformer.
2. The synchronous rectification flyback dc-dc power conversion device of claim 1, wherein: the direct current input voltage of the input circuit is direct current voltage directly output by direct current power supplies such as a storage battery and the like or direct current voltage output by other conversion circuits, and the direct current input voltage is constant direct current voltage or sine half-wave voltage output by alternating current voltage of a power grid through a diode rectification circuit.
3. The synchronous rectification flyback dc-dc power conversion device of claim 1, wherein: one end of a primary power winding of the transformer is connected with a direct-current input voltage anode, the other end of the primary power winding of the transformer is connected with a drain electrode of a primary power switch tube, a source electrode of the primary power switch tube is connected with a direct-current input voltage cathode, one end of a secondary power winding of the transformer is connected with a VD end of a synchronous rectification control circuit and a drain electrode of a secondary synchronous rectification tube, a grid electrode of the secondary synchronous rectification tube is connected with a VG end of the synchronous rectification control circuit, the other end of the secondary power winding of the transformer is connected with one end of a capacitor Co and one end of a load, and the other end of the capacitor Co is connected with the other end of the load, the source electrode of the secondary synchronous rectification tube and; the auxiliary switch is connected in parallel with the primary power winding of the transformer.
4. The synchronous rectification flyback dc-dc power conversion device of claim 1, wherein: one end of a primary power winding of the transformer is connected with a source electrode of a primary power switching tube, a drain electrode of the primary power switching tube is connected with a direct current input voltage anode, the other end of the primary power winding of the transformer is connected with a direct current input voltage cathode, one end of a secondary power winding of the transformer is connected with a VD (voltage distribution) end of the synchronous rectification control circuit and a drain electrode of a secondary synchronous rectification tube, a grid electrode of the secondary synchronous rectification tube is connected with a VG end of the synchronous rectification control circuit, the other end of the secondary power winding of the transformer is connected with one end of a capacitor Co and one end of a load, and the other end of the capacitor Co is connected with the other end of the load, the source electrode of the secondary synchronous rectification tube; the auxiliary switch is connected in parallel with the primary power winding of the transformer.
5. The synchronous rectification flyback dc-dc power conversion device of claim 1, wherein: the auxiliary switch is a semiconductor device with bidirectional blocking capability.
6. The synchronous rectification flyback dc-dc power conversion device of claim 1, wherein: the auxiliary switch is a composite switch formed by a diode and a metal oxide semiconductor field effect transistor, and the direction of the diode is opposite to that of the diode of the metal oxide semiconductor field effect transistor body.
7. The synchronous rectification flyback dc-dc power conversion device of claim 1, wherein: the auxiliary switch is a compound switch formed by two metal oxide semiconductor field effect transistors which are connected in series in an opposite direction.
8. The synchronous rectification flyback dc-dc power conversion device of claim 1, wherein: the conducting time of the auxiliary switch is fixed or is adjusted by a control circuit of the synchronous rectification flyback DC-DC power supply conversion device according to the working condition of the circuit.
9. The synchronous rectification flyback dc-dc power conversion device of claim 1, wherein: the exciting current of the transformer works in an intermittent state, a continuous state or a critical intermittent state.
10. The method for controlling a synchronous rectification flyback dc-dc power conversion device according to claim 1, wherein the method specifically comprises the steps of:
step 1: the synchronous rectification flyback DC-DC power supply conversion device respectively generates a control signal of a primary side power switch tube and a control signal of an auxiliary switch;
step 2: the auxiliary switch is conducted once or twice before the primary side power switch tube is switched on, so that the primary side power winding of the transformer is short-circuited during the conduction period of the auxiliary switch;
and step 3: the synchronous rectification control circuit generates a synchronous rectification tube control signal according to voltage signals at two ends of the secondary synchronous rectification tube.
11. The control method of the synchronous rectification flyback dc-dc power conversion device as claimed in claim 10, wherein the auxiliary switch is turned on once or twice before the primary side power switching tube is turned on when the synchronous rectification flyback dc-dc power conversion device operates in the current continuous mode; when the synchronous rectification flyback type direct current-direct current power supply conversion device works in a current discontinuous mode or a current critical discontinuous mode, the auxiliary switch is conducted once, twice or not before the primary side power switch tube is switched on.
CN201810360716.0A 2018-04-20 2018-04-20 Synchronous rectification flyback DC-DC power supply conversion device and control method Active CN108667304B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810360716.0A CN108667304B (en) 2018-04-20 2018-04-20 Synchronous rectification flyback DC-DC power supply conversion device and control method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810360716.0A CN108667304B (en) 2018-04-20 2018-04-20 Synchronous rectification flyback DC-DC power supply conversion device and control method

Publications (2)

Publication Number Publication Date
CN108667304A CN108667304A (en) 2018-10-16
CN108667304B true CN108667304B (en) 2021-05-11

Family

ID=63780532

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810360716.0A Active CN108667304B (en) 2018-04-20 2018-04-20 Synchronous rectification flyback DC-DC power supply conversion device and control method

Country Status (1)

Country Link
CN (1) CN108667304B (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112928925B (en) * 2021-02-01 2022-05-17 杭州电子科技大学 Active clamping flyback converter and implementation method thereof
CN113131749B (en) * 2021-03-16 2022-06-14 广州金升阳科技有限公司 Flyback converter and control method
CN113472213A (en) * 2021-07-30 2021-10-01 广州金升阳科技有限公司 Flyback converter

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104539163A (en) * 2014-12-19 2015-04-22 广州金升阳科技有限公司 Synchronous rectification control method for flyback converter and control module of synchronous rectification control method
CN106487234A (en) * 2016-11-21 2017-03-08 盐城工学院 The output power control method of the anti exciting converter of electric current blend modes of operation
CN206250979U (en) * 2016-12-14 2017-06-13 安徽博微智能电气有限公司 A kind of quasi-resonance active-clamp flyback converter

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1155151C (en) * 2000-12-01 2004-06-23 台达电子工业股份有限公司 Synchronous rectifier
US6552917B1 (en) * 2001-11-05 2003-04-22 Koninklijke Philips Electronics N.V. System and method for regulating multiple outputs in a DC-DC converter
CN2540657Y (en) * 2001-11-26 2003-03-19 王跃斌 Secondary synchronous rectification circuit for anti-excite type switch voltage-stabilized source

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104539163A (en) * 2014-12-19 2015-04-22 广州金升阳科技有限公司 Synchronous rectification control method for flyback converter and control module of synchronous rectification control method
CN106487234A (en) * 2016-11-21 2017-03-08 盐城工学院 The output power control method of the anti exciting converter of electric current blend modes of operation
CN206250979U (en) * 2016-12-14 2017-06-13 安徽博微智能电气有限公司 A kind of quasi-resonance active-clamp flyback converter

Also Published As

Publication number Publication date
CN108667304A (en) 2018-10-16

Similar Documents

Publication Publication Date Title
CN108448902B (en) Synchronous rectification flyback DC-DC power supply conversion device and control method
US10116222B2 (en) Soft switching flyback converter with primary control
US9054592B2 (en) Synchronous rectifying control method and circuit for isolated switching power supply
US6366476B1 (en) Switching power supply apparatus with active clamp circuit
CN101728958B (en) Method and control device for controlling isolated converter by tail current
US9287792B2 (en) Control method to reduce switching loss on MOSFET
CN108418435B (en) Synchronous rectification flyback DC-DC power supply conversion device
US8743565B2 (en) High power converter architecture
US9019724B2 (en) High power converter architecture
US11804780B2 (en) Multi-mode control method for active clamp flyback converter
US8619438B2 (en) Resonant converter
WO2012009998A1 (en) Llc series resonant converter and driving method thereof
JP2016174471A (en) Snubber circuit
TWI446133B (en) Method and control device for tail current control isolated converter
JP2009284667A (en) Power supply device, its control method, and semiconductor device
CN108667304B (en) Synchronous rectification flyback DC-DC power supply conversion device and control method
WO2020228818A1 (en) Synchronous rectification control system and method for quasi-resonant flyback converter
CN208158436U (en) A kind of synchronous rectification inverse-excitation type DC-DC power conversion equipment
KR101141374B1 (en) Boost converter
US11716010B2 (en) Driving control circuit, method and device for gallium nitride (GaN) transistor, and medium
CN113708631B (en) Flyback converter and control method thereof
CN113541501A (en) Flyback switching power supply and control method and circuit for improving conversion efficiency of flyback switching power supply
CN113162419A (en) Light-load circulating current suppression circuit based on peak current control
CN111404391A (en) Positive-shock active clamping driving circuit
WO2018157458A1 (en) Voltage absorption 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
GR01 Patent grant
GR01 Patent grant