CN109768708A - Zero voltage switching control circuit for flyback type electric source supply circuit - Google Patents
Zero voltage switching control circuit for flyback type electric source supply circuit Download PDFInfo
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Abstract
The present invention proposes a kind of zero voltage switching control circuit for flyback type electric source supply circuit, synchronous rectification transistor is connected twice in a switching cycle, to generate reverse current in first side winding, and after synchronous rectification transistor shutdown, the power transistor of primary side is connected, to realize zero voltage switching.There is a synchronization signal between primary side and secondary side, switching to synchronizing power transistor and synchronous rectification transistor, synchronization signal also generates zero-pressure switch pulse to trigger, and makes the power transistor of primary side realize zero voltage switching synchronous rectification transistor is connected.
Description
Technical field
The present invention relates to a kind of control circuits, particularly relate to a kind of zero voltage switching for flyback type electric source supply circuit
Control circuit.
Background technique
Fig. 1 shows a kind of flyback type electric source supply circuit (flyback type electric source supply circuit 1) of prior art, wherein once
Side control circuit 80 controls power transistor QP and generates output voltage Vo with power switched transformer 10, secondary side control circuit
90, to generate synchronous rectification control signal VG, the synchronous rectification of secondary side are carried out to control synchronous rectification transistor QSR.
The prior art shown in Fig. 1, its shortcoming is that, synchronous rectification transistor QSR can not be in real time and accurately with one
The power transistor QP of secondary side is synchronous, and power transistor QP is in the case where carrying out zero voltage switching, power supply conversion efficiency
It is poor.
The prior art of the present invention compared to Fig. 1, can be accurately synchronous with the power transistor QP of primary side, and passes through phase
Same synchronization signal, power transistor QP can realize zero voltage switching when switching, effectively improve power supply conversion efficiency.
Summary of the invention
It is an object of the invention to overcome the deficiencies in the prior art and defect, propose a kind of for flyback type electric source supply electricity
The zero voltage switching control circuit on road, can be accurately synchronous with the power transistor QP of primary side, and passes through identical synchronization
Signal, power transistor QP can realize zero voltage switching when switching, effectively improve power supply conversion efficiency.
In order to achieve the above-mentioned object of the invention, one of viewpoint is sayed that the present invention provides a kind of controls of zero voltage switching
Circuit, to control a flyback type electric source supply circuit, which includes: a primary side control circuit,
To generate a switching signal and a synchronous commutation synchronization signal, the switching signal is to control a power transistor to switch
One power transformer and generate an output voltage；One secondary side control circuit, to generate synchronous rectification control signal, with control
The conducting and shutdown of a synchronous rectification transistor are made, wherein synchronous rectification control signal has a synchronous commutating pulse and one
A synchronous rectification period is connected to control the synchronous rectification transistor in zero-pressure switch pulse, the synchronous rectification pulse；And one
Pulse transformer, to couple the synchronous rectification synchronization signal from the primary side control circuit, to be sent to secondary side control
Circuit and generate the synchronous rectification control signal；Wherein synchronous rectification control signal is touched according to the synchronous rectification synchronization signal
Hair generates the zero-pressure switch pulse, when which controls synchronous rectification transistor conducting one preset zero-pressure switching
Section triggers power transistor conducting when the zero-pressure switch pulse terminates and turns off the synchronous rectification transistor, so that
The power transistor realizes zero voltage switching.
In a preferred embodiment, when the zero-pressure switch pulse terminates and turns off the synchronous rectification transistor, in triggering
It also include a preset zero-pressure switching delay period before power transistor conducting.
In a preferred embodiment, it is operated under discontinuous conducting (DCM) mode in the power transformer, with the zero-pressure
Switch pulse controls synchronous rectification transistor conducting.
In a preferred embodiment, after power transistor shutdown, the synchronous rectification pulse control synchronous rectification crystalline substance
The synchronous rectification period is connected in body pipe, to carry out the synchronous rectification of secondary side, wherein after the synchronous rectification end-of-pulsing, when connecing
When receiving the synchronous rectification synchronization signal, triggering generates the zero-pressure switch pulse so that the synchronous rectification transistor is connected.
In a preferred embodiment, when a drain terminal voltage of the synchronous rectification transistor is less than a low voltage threshold,
Synchronous rectification control signal generates the zero-pressure switch pulse so that the synchronous rectification transistor is connected.
In a preferred embodiment, after the zero-pressure switch pulse terminates and turns off the synchronous rectification transistor, and working as should
When the cross-pressure of one auxiliary winding of power transformer is lower than a first side winding threshold value, when starting the preset zero-pressure switching delay
Section；Wherein the auxiliary winding is coupled to the primary side control circuit.
In a preferred embodiment, the pulse width of the synchronous rectification synchronization signal determines rising for the zero-pressure switch pulse
Begin.
In a preferred embodiment, which determines the frequency of the synchronous rectification synchronization signal.
In a preferred embodiment, the pulse width of the synchronous rectification synchronization signal is less than 1 microsecond.
Another viewpoint is sayed that present invention provides a kind of zero voltage switching control circuits, to control a flyback
Power supply circuit, which includes: a primary side control circuit, should to generate a switching signal
Switching signal generates an output voltage to control a power transistor to switch a power transformer；One secondary side control electricity
Road, to generate synchronous rectification control signal and a PWM synchronization signal, synchronous rectification control signal control one synchronizes whole
The conducting and shutdown of transistor are flowed, wherein there is synchronous rectification control signal a synchronous commutating pulse and a zero-pressure to switch arteries and veins
A synchronous rectification period is connected to control the synchronous rectification transistor in punching, the synchronous rectification pulse；And a pulse transformer,
To couple the PWM synchronization signal from the secondary side control circuit, cut with being sent to a primary side control circuit to generate this
Change signal；Wherein before the PWM synchronization signal sends out a lock-out pulse, which controls the synchronous rectification crystal
The zero-pressure switching period is connected in pipe；When the zero-pressure switch pulse terminates and turns off the synchronous rectification transistor, it is same to generate the PWM
Step signal is to trigger power transistor conducting, so that the power transistor realizes zero voltage switching.
In a preferred embodiment, when the flyback type electric source supply circuit operation at light load, do not generate the zero-pressure switching
Pulse.
In a preferred embodiment, when the zero-pressure switch pulse terminates and turns off the synchronous rectification transistor, this is secondary
Side control circuit starts the preset zero-pressure switching delay period.
In a preferred embodiment, which determines the frequency of the switching signal.
In a preferred embodiment, the pulse width of the PWM synchronization signal is less than 1 microsecond.
Below by way of specific embodiment elaborate, should be easier to understand the purpose of the present invention, technology contents, feature and
The effect of it is realized.
Detailed description of the invention
Fig. 1 shows a kind of schematic diagram of prior art flyback type electric source supply circuit；
Fig. 2A -2B shows a kind of embodiment schematic diagram of zero voltage switching control circuit of the invention；
Fig. 3 shows the waveform diagram of the embodiment corresponding to zero voltage switching control circuit of the invention；
Fig. 4 shows a kind of specific embodiment schematic diagram of zero voltage switching control circuit of the invention；
Fig. 5 shows another specific embodiment schematic diagram of zero voltage switching control circuit of the invention；
Fig. 6 shows the waveform diagram of the embodiment corresponding to Fig. 5；
Fig. 7 A-7B shows the waveform diagram of the embodiment corresponding to Fig. 5.
Specific embodiment
Attached drawing in the present invention belongs to signal, is mostly intended to indicate coupling relationship and each signal waveform between each circuit
Between relationship, as circuit, signal waveform and frequency then and not according to ratio draw.
Fig. 2A is please referred to, (no-voltage is cut as shown in the figure for a kind of embodiment of zero voltage switching control circuit of the invention
Change control circuit 501), zero voltage switching control circuit 501 is to control flyback type electric source supply circuit 2, zero voltage switching control
Circuit 501 processed includes primary side control circuit 80, secondary side control circuit 90 and pulse transformer 20.Primary side control electricity
Road 80 is produced to generate a switching signal Vs, switching signal Vs to control power transistor QP with power switched transformer 10
Raw output voltage Vo.Secondary side control circuit 90 is to generate synchronous rectification control signal VG, to control a synchronous rectification crystal
The conducting and shutdown of pipe QSR.
It is turned off once again again after power transistor QP conducting, and to first side winding W1 degaussing, and synchronous rectification transistor
When QSR is connected, power transformer 10 can be in secondary side winding W2 induction cycle current Is (as shown in Figure 2 A), circulating current Is meeting
Energy is shifted to secondary side winding W2, when synchronous rectification transistor QSR is turned off once again, power transformer 10 from output capacitance CO
It can be in first side winding W1 induction cycle current Ip (as shown in Figure 2 B), according to the present invention, the circulating current of first side winding W1
The parasitic capacitance CP of power transistor QP can be discharged to substantially 0V by Ip, and charge is recharged to input capacitance CI, work as function
Rate transistor QP is then turned on, and power transistor QP can be made to realize zero voltage switching (ZVS-Zero Voltage
Switching)。
" zero voltage switching " above-mentioned refers to, before transistor will be connected, passes through a discharge current posting transistor
Raw capacitor is discharged to 0V, and charge is recharged into the element of no energy loss, so that drain-source voltage is first when transistor turns
It is reduced to 0V, parasitic capacitance is not discharged with the conducting resistance of transistor, and power supply conversion efficiency can be improved.
Furthermore it should be noted that: mutual matching is not necessarily between the ghost effect of itself or part because of circuit component
Ideal, therefore, although parasitic capacitance CP to be made electric discharge is 0V, actual capabilities simultaneously can not accurately be discharged to 0V, and only connect
Nearly 0V, it is, according to the present invention, being subjected to the undesirable property due to circuit and making the voltage and 0V after parasitic capacitance CP electric discharge
Between have a degree of error, this be exactly it is above-mentioned be discharged to " generally " be 0V meaning, herein other mention " substantially
On " place it is also identical.
Show that the waveform of the embodiment corresponding to zero voltage switching control circuit of the invention shows please refer to Fig. 3, Fig. 3
It is intended to.According to the present invention, synchronous rectification control signal VG can have synchronous rectification pulse PSR and zero-pressure switch pulse PZV, together
A synchronous rectification period T_SR is connected to control synchronous rectification transistor QSR in step commutating pulse PSR, wherein when synchronous rectification
Section T_SR is generally synchronized with the turn-on time of circulating current Is, can so promote power supply conversion efficiency；On the other hand, zero-pressure is cut
It changes pulse PZV then and can be used for the zero voltage switching of power transistor QP above-mentioned.
Pulse transformer 20 is to isolated transmission mode (indirect in electrical contact), in primary side control circuit 80
Synchronization signal is transmitted between secondary side control circuit 90, signal VG is controlled with synchronism switching signal Vs and synchronous rectification.Specifically
For, pulse transformer 20 can be used to synchronize synchronous rectification pulse PSR above-mentioned and zero-pressure switching arteries and veins by synchronization signal
PZV is rushed, while can realize the synchronous rectification of secondary side, and power transistor QP is made to realize zero voltage switching, implementation detail will
After being specified in.
Referring to Fig. 4, being as shown in the figure a kind of specific embodiment (no-voltage of zero voltage switching control circuit of the invention
Control switching circuit 502), in the present embodiment, pulse transformer 20 is same to couple synchronous rectification from primary side control circuit 100
Signal SR_sync is walked, synchronous rectification control signal VG is generated to be sent to secondary side control circuit 200；Please refer to figure
3, in detail, synchronous rectification control signal VG is triggered according to synchronous rectification synchronization signal SR_sync generates zero-pressure switch pulse
The preset zero-pressure switching period T_ZVS of PZV, zero-pressure switch pulse PZV control synchronous rectification transistor QSR conducting one (such as t1-
T2), when zero-pressure switch pulse PZV terminates and turns off synchronous rectification transistor QSR (such as t2), triggering power transistor QP is led
Logical (such as t3-t4), as previously mentioned, preset zero-pressure switching period T_ZVS can put the parasitic capacitance CP of power transistor QP
Electricity is to substantially 0, so that (such as t3-t4) is, it can be achieved that zero voltage switching when power transistor QP is connected.
Please continue to refer to Fig. 4 and Fig. 3, in one embodiment, synchronous rectification crystalline substance is turned off when zero-pressure switch pulse PZV terminates
When body pipe QSR, before triggering power transistor QP conducting, also comprising a preset zero-pressure switching delay period Td (such as t2-
t3).In one embodiment, this preset zero-pressure switching delay period Td can ensure that power transistor QP will not be with synchronous rectification crystalline substance
Body pipe QSR is simultaneously turned on, and in one embodiment, this preset zero-pressure switching delay period Td can ensure that power transistor QP more
For accurate zero voltage switching.
Please continue to refer to Fig. 4 and Fig. 3, in one embodiment, zero voltage switching control circuit of the invention, in power transformation
Device 10 operates under discontinuous conducting (DCM) mode, controls conducting synchronous rectification transistor QSR with zero-pressure switch pulse PZV.
Please continue to refer to Fig. 3, in one embodiment, (such as t4), synchronous rectification pulse after power transistor QP shutdown
PSR controls synchronous rectification transistor QSR conducting synchronous rectification period T_SR (such as t5-t6), whole to carry out synchronizing for secondary side
Stream, wherein after synchronous rectification pulse PSR (such as t6), when receiving synchronous rectification synchronization signal SR_sync (such as
T7 or t0), triggering generates zero-pressure switch pulse PZV (such as t8 or t1) so that synchronous rectification transistor QSR is connected.
Please continue to refer to Fig. 4 and Fig. 3, in one embodiment, when the drain terminal voltage VTR of synchronous rectification transistor QSR is small
When a low voltage threshold VT2 (such as t0 or t7), it is same to be connected that synchronous rectification control signal VG generates zero-pressure switch pulse PZV
Rectifying transistor QSR is walked, so makes synchronous rectification transistor QSR that can also realize zero voltage switching, further increases power supply conversion
Efficiency.In one embodiment, this condition can also be omitted, it is, without judging that low voltage threshold VT2 can be according to other conditions
And generate zero-pressure switch pulse PZV.
Please continue to refer to Fig. 4 and Fig. 3, in one embodiment, synchronous rectification crystalline substance is turned off when zero-pressure switch pulse PZV terminates
After body pipe QSR, and when the cross-pressure VM of the auxiliary winding WA of power transformer 10 is lower than first side winding threshold value VT1 (such as
T2 '), start preset zero-pressure switching delay period Td, it can be ensured that the more accurate zero voltage switching of power transistor QP；Such as figure
Shown in 4, auxiliary winding WA is coupled to primary side control circuit 80 to obtain the cross-pressure VM of auxiliary winding WA or its coherent signal.?
In one embodiment, the condition in relation to first side winding threshold value VT1 can also be omitted.
In one embodiment, the pulse width of synchronous rectification synchronization signal SR_sync determines rising for zero-pressure switch pulse PZV
Begin.For a viewpoint, the mode of zero-pressure switch pulse PZV triggering can be as shown in Figure 3 by synchronous rectification synchronization signal SR_
The negative edge of sync triggers, but in other embodiments, however it is not limited to this, such as can also be with synchronous rectification synchronization signal SR_sync
Positive edge trigger zero-pressure switch pulse PZV.
Please continue to refer to Fig. 4, in one embodiment, the frequency Fs of synchronous rectification synchronization signal SR_sync is by primary side control
Circuit 100 processed is determined that in one embodiment, primary side control circuit 100 may include an oscillator 110, to generate synchronization
Commutation synchronization signal SR_sync and determine its frequency Fs.One implement in, frequency Fs can for a fixed value (such as flyback electricity
Source supply circuit 4 is that fixed frequency operates), it or is an adjustable value, or can be that (such as flyback type electric source supply circuit 4 is change value
Non- fixed frequency operates).
In a preferred embodiment, the pulse width T_sync of synchronous rectification synchronization signal SR_sync can only be accounted for its period
Very little part, in one embodiment, the pulse width T_sync of synchronous rectification synchronization signal SR_sync is less than 1 microsecond.
A kind of specific implementation of zero voltage switching control circuit of the invention is shown please refer to Fig. 5 and Fig. 6, Fig. 5
Example (zero voltage switching control circuit 503), Fig. 6 then show the waveform diagram corresponding to Fig. 5 embodiment.
In Fig. 5, zero voltage switching control circuit 503 is similar with zero voltage switching control circuit 502, and difference exists
In in zero voltage switching control circuit 503, pulse transformer 20 is to couple PWM synchronization signal from secondary side control circuit 400
PWM_SYNC to be sent to primary side control circuit 300 to generate switching signal Vs, and controls power transistor QP to switch function
Rate transformer 10 and generate output voltage Vo.
Please continue to refer to Fig. 5 and Fig. 6, in the present embodiment, synchronous rectification control signal VG also has synchronous rectification pulse PSR
And zero-pressure switch pulse PZV.Wherein before PWM synchronization signal PWM_SYNC sends out lock-out pulse PPS, zero-pressure switch pulse
PZV controls synchronous rectification transistor QSR conducting zero-pressure switching period T_ZVS (t1-t2 of such as Fig. 6), as zero-pressure switch pulse PZV
When terminating and turning off synchronous rectification transistor QSR (t2 of such as Fig. 6), PWM synchronization signal PWM_SYNC is generated to trigger power crystalline substance
(t4-t5 of such as Fig. 6, similar with operating principle above-mentioned by switching signal Vs), synchronous rectification transistor is connected in body pipe QP
After zero-pressure switching period T_ZVS is connected in QSR, first side winding W1 induction can be made to generate circulating current Ip, and by power transistor
The parasitic capacitance CP of QP is discharged to substantially 0, when then generate PWM synchronization signal PWM_SYNC to trigger power transistor QP
Conducting may make power transistor QP to realize zero voltage switching.
Please continue to refer to Fig. 6, in one embodiment, when zero-pressure switch pulse PZV terminates and synchronous rectification transistor is turned off
When QSR, before triggering power transistor QP conducting, also after a preset zero-pressure switching delay period Td (t2-t4 of such as Fig. 6)
Just triggering power transistor QP conducting.In one embodiment, this preset zero-pressure switching delay period Td can ensure that power crystal
Pipe QP will not be simultaneously turned on synchronous rectification transistor QSR, and in one embodiment, this preset zero-pressure switching delay period Td
It can ensure that the more accurate zero voltage switching of power transistor QP.
Please continue to refer to Fig. 6, in one embodiment, zero voltage switching control circuit 503 is operated in power transformer 10
Under one discontinuous conducting (DCM) mode, conducting synchronous rectification transistor QSR conducting is controlled with zero-pressure switch pulse PZV.
Please continue to refer to Fig. 6, in one embodiment, when the drain voltage of synchronous rectification transistor QSR is lower than a low-voltage
When threshold value VT2 (t0 of such as Fig. 6), when zero-pressure switch pulse PZV controls synchronous rectification transistor QSR conducting preset zero-pressure switching
Section T_ZVS.
It in one embodiment, can be by secondary when zero-pressure switch pulse PZV terminates and turns off synchronous rectification transistor QSR
Side control circuit 400 starts preset zero-pressure switching delay period Td.For a viewpoint, PWM synchronization signal PWM_SYNC touching
Send out the mode of switching signal, however it is not limited to as shown in fig. 6, triggering (t2 of such as Fig. 6) with the positive edge of lock-out pulse PPS, and pass through
After zero-pressure switching delay period Td (t4 of such as Fig. 6), switching signal Vs ability conducting power transistor QP.In one embodiment, zero
Crush-cutting change delay periods Td can also motor synchronizing pulse PPS negative edge triggering (it is, Td can be such as t3-t4 of Fig. 6).In other realities
It applies in example, PWM synchronization signal PWM_SYNC triggers the mode of switching signal, can also be cut by secondary side control circuit 400 in zero-pressure
When changing pulse PZV terminates and turn off synchronous rectification transistor QSR, after zero-pressure switching delay period Td, just pass through synchronous arteries and veins
Rush PPS positive edge triggering (such as t4 of Fig. 7 A) or negative edge triggering (such as t4 of Fig. 7 B) switching signal Vs and conducting power transistor
QP。
Please continue to refer to Fig. 5, in one embodiment, the frequency Fs ' of switching signal Vs is determined by secondary side control circuit 400
It is fixed.In one embodiment, secondary side control circuit 400 may include an oscillator 410, to generate PWM synchronization signal PWM_
SYNC and determine its frequency Fs '.In implementing one, frequency Fs ' can (such as flyback type electric source supply circuit 5 be for a fixed value
Fixed frequency operates), or be an adjustable value, or can be change value (such as flyback type electric source supply circuit 5 is that non-fixed frequency operates).
In a preferred embodiment, the pulse width T_sync of PWM synchronization signal PWM_SYNC can only account for its period very
Small part, in one embodiment, the pulse width T_sync of PWM synchronization signal PWM_SYNC is less than 1 microsecond.
In addition, in one embodiment, when flyback type electric source supply circuit operation of the invention is at light load, zero-pressure is not generated
Switch pulse PZV, in other words, zero voltage switching control circuit of the invention can adjust whether generate zero-pressure according to load state
Switch pulse PZV, when load current be underloading or pole at light load, adjust zero voltage switching control circuit (no-voltage of the invention
503) control switching circuit 501,502 makes it not generate zero-pressure switch pulse PZV, can further promote power supply conversion effect
Rate.
Illustrate the present invention for preferred embodiment above, but described above, is only easy to those skilled in the art
Understand the contents of the present invention, interest field not for the purpose of limiting the invention.Illustrated each embodiment, however it is not limited to individually
Using, it can also be with combined application, for example, two or more embodiments can be with united application, and the portion in an embodiment
It is grouped as and is also substituted for corresponding building block in another embodiment.In addition, under same spirit of the invention, this field
Technical staff is contemplated that various equivalence changes and various combinations, for example, alleged by the present invention " at certain signal
Reason or operation generate certain output result ", it is not limited to itself be carried out the signal also comprising when necessary according to the signal
Voltage to current transducer, Current Voltage conversion and/or ratio conversion etc., carry out processing or operation according to the signal after conversion later
Generate certain output result.It follows that under same spirit of the invention, it may occur to persons skilled in the art that various equivalent changes
Change and various combinations, a combination thereof mode is a lot of, explanation numerous to list herein.Therefore, the scope of the present invention should cover above-mentioned
And other all equivalence changes.
Claims (17)
1. a kind of zero voltage switching control circuit, to control a flyback type electric source supply circuit, zero voltage switching control electricity
Road includes:
One primary side control circuit, to generate a switching signal and a synchronous commutation synchronization signal, the switching signal to
It controls a power transistor and generates an output voltage to switch a power transformer；
One secondary side control circuit, to generate synchronous rectification control signal, to control the conducting of a synchronous rectification transistor
With shutdown, wherein synchronous rectification control signal has a synchronous commutating pulse and a zero-pressure switch pulse, the synchronous rectification
A synchronous rectification period is connected to control the synchronous rectification transistor in pulse；And
One pulse transformer, it is secondary to be sent to this to couple the synchronous rectification synchronization signal from the primary side control circuit
Side control circuit and generate the synchronous rectification control signal；
Wherein synchronous rectification control signal is triggered according to the synchronous rectification synchronization signal generates the zero-pressure switch pulse, this zero
Crush-cutting changes the one preset zero-pressure switching period of pulse control synchronous rectification transistor conducting, terminate when the zero-pressure switch pulse and
When turning off the synchronous rectification transistor, power transistor conducting is triggered, so that the power transistor realizes that no-voltage is cut
It changes.
2. zero voltage switching control circuit according to claim 1, wherein when the zero-pressure switch pulse terminates and turn off this
It also include a preset zero-pressure switching delay period before triggering the power transistor conducting when synchronous rectification transistor.
3. zero voltage switching control circuit according to claim 1, wherein it is discontinuous to operate in one in the power transformer
Under conduction mode, synchronous rectification transistor conducting is controlled with the zero-pressure switch pulse.
4. zero voltage switching control circuit according to claim 1, wherein after power transistor shutdown, the synchronization
Commutating pulse controls the synchronous rectification transistor and the synchronous rectification period is connected, to carry out the synchronous rectification of secondary side, wherein in
After the synchronous rectification end-of-pulsing, when receiving the synchronous rectification synchronization signal, triggering generates the zero-pressure switch pulse to lead
Lead to the synchronous rectification transistor.
5. zero voltage switching control circuit according to claim 1, wherein when a drain electrode end of the synchronous rectification transistor
When voltage is less than a low voltage threshold, synchronous rectification control signal generates the zero-pressure switch pulse so that synchronous rectification crystalline substance is connected
Body pipe.
6. zero voltage switching control circuit according to claim 2, wherein when the zero-pressure switch pulse terminates and turn off this
After synchronous rectification transistor, and when the cross-pressure of an auxiliary winding of the power transformer is lower than a first side winding threshold value, open
Move the preset zero-pressure switching delay period；Wherein the auxiliary winding is coupled to the primary side control circuit.
7. zero voltage switching control circuit according to claim 1, wherein the pulse width of the synchronous rectification synchronization signal
Determine the starting of the zero-pressure switch pulse.
8. zero voltage switching control circuit according to claim 1, wherein it is whole that the primary side control circuit determines that this is synchronized
Flow the frequency of synchronization signal.
9. zero voltage switching control circuit according to claim 1, wherein the pulse width of the synchronous rectification synchronization signal
Less than 1 microsecond.
10. a kind of zero voltage switching control circuit, to control a flyback type electric source supply circuit, zero voltage switching control electricity
Road includes:
One primary side control circuit, to generate a switching signal, the switching signal is to control a power transistor to switch
One power transformer and generate an output voltage；
One secondary side control circuit, to generate synchronous rectification control signal and a PWM synchronization signal, the synchronous rectification control
Signal processed controls the conducting and shutdown of a synchronous rectification transistor, and wherein synchronous rectification control signal has a synchronous rectification arteries and veins
Punching and a zero-pressure switch pulse, when which is connected a synchronous rectification to control the synchronous rectification transistor
Section；And
One pulse transformer, to couple the PWM synchronization signal from the secondary side control circuit, to be sent to the primary side control
Circuit processed is to generate the switching signal；
Wherein before the PWM synchronization signal sends out a lock-out pulse, which controls the synchronous rectification transistor
The zero-pressure switching period is connected；When the zero-pressure switch pulse terminates and turns off the synchronous rectification transistor, it is synchronous to generate the PWM
Signal is to trigger power transistor conducting, so that the power transistor realizes zero voltage switching.
11. zero voltage switching control circuit according to claim 10, wherein when the zero-pressure switch pulse terminates and turn off
When the synchronous rectification transistor, power transistor conducting is also triggered after a preset zero-pressure switching delay period.
12. zero voltage switching control circuit according to claim 10, wherein do not connect when the power transformer operates in one
When continuous conduction mode, which is controlled with the zero-pressure switch pulse, the preset zero-pressure switching period is connected.
13. zero voltage switching control circuit according to claim 10, wherein when the flyback type electric source supply circuit operation
In at light load, not generating the zero-pressure switch pulse.
14. zero voltage switching control circuit according to claim 10, wherein when the drain electrode electricity of the synchronous rectification transistor
Force down when a low pressure threshold, the zero-pressure switch pulse control the synchronous rectification transistor be connected the preset zero-pressure switching when
Section.
15. zero voltage switching control circuit according to claim 11, wherein when the zero-pressure switch pulse terminates and turn off
When the synchronous rectification transistor, which starts the preset zero-pressure switching delay period.
16. zero voltage switching control circuit according to claim 10, wherein the secondary side control circuit determines the switching
The frequency of signal.
17. zero voltage switching control circuit according to claim 10, wherein the pulse width of the PWM synchronization signal is small
In 1 microsecond.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US16/134,906 US10566893B2 (en) | 2017-11-10 | 2018-09-18 | ZVS control circuit for use in a flyback power converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201762584714P | 2017-11-10 | 2017-11-10 | |
| US62/584,714 | 2017-11-10 |
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| CN109768708B CN109768708B (en) | 2021-04-27 |
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| CN201810480345.XA Expired - Fee Related CN109768708B (en) | 2017-11-10 | 2018-05-18 | Zero voltage switching control circuit for flyback power supply circuit |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110798075A (en) * | 2019-11-08 | 2020-02-14 | 矽力杰半导体技术(杭州)有限公司 | Control circuit and switching converter using same |
| CN111293892A (en) * | 2020-03-24 | 2020-06-16 | 福州瑞芯微电子股份有限公司 | Control circuit, control method, chip and flyback converter |
| CN112671239A (en) * | 2019-10-15 | 2021-04-16 | 立锜科技股份有限公司 | Flyback power supply circuit and secondary side control circuit and control method thereof |
| CN112713778A (en) * | 2019-10-24 | 2021-04-27 | 立锜科技股份有限公司 | Switching control circuit and method for controlling flyback power supply circuit |
| TWI798702B (en) * | 2021-05-20 | 2023-04-11 | 芯巧科技股份有限公司 | Synchronous Rectification Controller |
| US11777408B2 (en) | 2021-05-19 | 2023-10-03 | Delta Electronics (Shanghai) Co., Ltd. | Converter adaptable to wide range output voltage and control method thereof |
| WO2024125262A1 (en) * | 2022-12-15 | 2024-06-20 | 华为技术有限公司 | Switching power supply circuit, switching power supply, electronic device and power supply system |
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| CN1478318A (en) * | 2000-11-11 | 2004-02-25 | ������������ʽ���� | Power converter |
| US20100033995A1 (en) * | 2008-08-11 | 2010-02-11 | Fsp Technology Inc. | Flyback circuit providing synchronized control |
| CN106059304A (en) * | 2015-04-09 | 2016-10-26 | 电力集成公司 | Active reduced voltage switching using secondary switch |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112671239A (en) * | 2019-10-15 | 2021-04-16 | 立锜科技股份有限公司 | Flyback power supply circuit and secondary side control circuit and control method thereof |
| CN112671239B (en) * | 2019-10-15 | 2024-02-27 | 立锜科技股份有限公司 | Flyback power supply circuit, secondary side control circuit and control method thereof |
| CN112713778A (en) * | 2019-10-24 | 2021-04-27 | 立锜科技股份有限公司 | Switching control circuit and method for controlling flyback power supply circuit |
| CN112713778B (en) * | 2019-10-24 | 2022-03-29 | 立锜科技股份有限公司 | Switching control circuit and method for controlling flyback power supply circuit |
| CN110798075A (en) * | 2019-11-08 | 2020-02-14 | 矽力杰半导体技术(杭州)有限公司 | Control circuit and switching converter using same |
| CN110798075B (en) * | 2019-11-08 | 2021-04-02 | 矽力杰半导体技术(杭州)有限公司 | Control circuit and switching converter using same |
| CN111293892A (en) * | 2020-03-24 | 2020-06-16 | 福州瑞芯微电子股份有限公司 | Control circuit, control method, chip and flyback converter |
| US11777408B2 (en) | 2021-05-19 | 2023-10-03 | Delta Electronics (Shanghai) Co., Ltd. | Converter adaptable to wide range output voltage and control method thereof |
| TWI798702B (en) * | 2021-05-20 | 2023-04-11 | 芯巧科技股份有限公司 | Synchronous Rectification Controller |
| WO2024125262A1 (en) * | 2022-12-15 | 2024-06-20 | 华为技术有限公司 | Switching power supply circuit, switching power supply, electronic device and power supply system |
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| CN109768708B (en) | 2021-04-27 |
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