CN109713904A - Flyback power-switching circuit and conversion control circuit therein and control method - Google Patents
Flyback power-switching circuit and conversion control circuit therein and control method Download PDFInfo
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Abstract
A kind of flyback power-switching circuit and conversion control circuit therein and control method, the flyback power-switching circuit, comprising: a transformer, it includes a first side windings, are coupled to an input power and a secondary side winding, are coupled to an output node；One primary side switch, is coupled to the first side winding, to switch the input power, and the secondary side winding is made to generate an out-put supply in the output node；One clamp circuit a, comprising: auxiliary switch and an auxiliary capacitor connect with the auxiliary switch and form an auxiliary branch, and the auxiliary branch is in parallel with the first side winding；An and conversion control circuit, it is not turned in the period in the primary side of primary side switch, turn-on time is estimated according to the one of a parasitic diode of auxiliary switch, and controls one auxiliary turn-on time of auxiliary switch conducting, wherein the auxiliary turn-on time is approximately equal to and is overlapped this and estimates turn-on time.
Description
Technical field
The present invention relates to a kind of flyback power-switching circuits, particularly relate to a kind of flyback power supply with active clamping
Conversion circuit.The invention further relates to for the conversion control circuit and its control method in flyback.
Background technique
Fig. 1 discloses a kind of flyback power supply conversion electricity with active clamping (active clamping) of prior art
Road (flyback power-switching circuit 1), flyback power-switching circuit 1 input voltage is converted to an output voltage,
It includes an an auxiliary switch S2 and auxiliary capacitor Cr, form an active clamping branch, the active clamping branch is in primary
Conducting when side switch S1 is not turned on makes the leakage inductance Lr and magnetizing inductance Lm of first side winding that when institute be connected in primary side switch S1
The energy of storage can be released by this branch and is stored among auxiliary capacitor Cr, in addition, it is connected in primary side switch S1
Before, it can be discharged the parasitic capacitance Coss of primary side switch S1, by the energy being stored in auxiliary capacitor Cr so that once
It is zero voltage switching (Zero Voltage Switching, ZVS) when side switch S1 is connected, please refer to Fig. 2A, this is existing
In technology, the switching of primary side switch S1 and auxiliary switch S2 generally reverse phase each other.
The prior art shown in Fig. 1, its shortcoming is that, due to primary side switch S1 and auxiliary switch S2 switching substantially
On reverse phase each other, therefore the turn-on time of auxiliary switch S2 may be too long, and causes biggish circular electric current (circulation
Current), power loss is further resulted in.
Fig. 2 B discloses the flyback power supply conversion with active clamping (active clamping) of another prior art
The waveform diagram of circuit, the prior art is similar with the prior art shown in Fig. 1, the difference is that auxiliary switch S2's leads
The logical time is not generally reverse phase in primary side switch S1, the present embodiment, and auxiliary switch S2 conducting is led in primary side switch S1
Before logical, and its turn-on time TONA is a fixed turn-on time.
The prior art shown in Fig. 2 B, its shortcoming is that, since the turn-on time TONA of auxiliary switch S2 is one fixed
Turn-on time, therefore under such as higher application of input voltage VI, the turn-on time TONA of auxiliary switch S2 may be not enough to
Charge in parasitic capacitance Coss to primary side switch S1 is discharged completely, so that primary side switch S1 can not reach no-voltage
Switching, further results in power loss.In addition, in the prior art, when primary side switch S1 is just switched to and is not turned on, auxiliary
The parasitic diode D2 of switch S2 may be connected, that is, as in the TOD2 period in figure, auxiliary capacitor electric current ICr by
Parasitic diode D2 is connected, and the reverse reverting charge effect of the parasitic diode D2 due to auxiliary switch S2, that is,
Reverse recovery charge (Qrr) effect, can make charge of the physical holding of the stock in auxiliary capacitor Cr become smaller,
It may be insufficient so as to be zero voltage switching when primary side switch S1 is connected；On the other hand, it is opened according to the lesser auxiliary of Qrr
It closes, such as, but not limited to GaAs switch, the forward voltage of parasitic diode is usually larger, thus will cause additional power damage
Consumption.
The turn-on time TONA of the prior art of the present invention compared to Fig. 1 and 2, adjustable auxiliary switch S2 is primary to ensure
Side switch S1 may achieve zero voltage switching, thus cpable of lowering power loses, and improve power supply conversion efficiency, in addition, of the invention
Auxiliary switch S2 can be connected in estimating in turn-on time for parasitic diode D2, therefore can effectively eliminate Qrr effect, or reduce
The added power dissipation as caused by the forward voltage of parasitic diode D2.
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 flyback power-switching circuit and
Conversion control circuit therein and control method, cpable of lowering power loss, and improve power supply conversion efficiency；It can also effectively eliminate
Qrr effect, or reduce the added power dissipation as caused by the forward voltage of parasitic diode.
In order to achieve the above-mentioned object of the invention, one of viewpoint is sayed that the present invention provides a kind of conversions of flyback power supply
Circuit includes: a transformer, and it includes a first side windings, is coupled to an input power and a secondary side winding, coupling
In an output node；One primary side switch, is coupled to the first side winding, to switch the first side winding to convert the input
Power supply, and the secondary side winding is made to generate an out-put supply in the output node；One clamp circuit a, comprising: auxiliary switch, packet
Include a parasitic diode；And an auxiliary capacitor, it connects with the auxiliary switch and forms an auxiliary branch, and the auxiliary branch
It is in parallel with the first side winding；And a conversion control circuit, to control primary side switch and the auxiliary switch, and turn
The input power is changed to generate the out-put supply, wherein the auxiliary switch is non-for complementary switching with primary side switch；The conversion
Control circuit includes: a power switch control circuit, is opened to generate a primary side switch control signal with controlling the primary side
It closes；And an auxiliary switch control circuit, to generate auxiliary switch control signal, and one in primary side switch is primary
Side was not turned in the period, estimated turn-on time according to the one of the parasitic diode, and it is auxiliary to control auxiliary switch conducting one first
Turn-on time is helped, wherein the first auxiliary turn-on time is approximately equal to and is overlapped this and estimates turn-on time.
In a preferred embodiment, the auxiliary switch control circuit, is not turned in the period in the primary side, first auxiliary in this
After helping turn-on time, one second auxiliary turn-on time of auxiliary switch conducting is more controlled.
In a preferred embodiment, which determines that second auxiliary is led according at least one following
The logical time a: current related signals, the input voltage and the output voltage；Wherein the current related signals be relevant to it is following extremely
It is one of few: the output electric current, the conducting electric current of primary side switch and the electric current of the first side winding.
In a preferred embodiment, the first auxiliary turn-on time and the second auxiliary turn-on time be not be overlapped, and in this
Between first auxiliary turn-on time and the second auxiliary turn-on time, which is to be not turned on.
In a preferred embodiment, which more adjusts the first auxiliary turn-on time so that this
One auxiliary turn-on time length is substantially the same with the second auxiliary turn-on time length.
In a preferred embodiment, the auxiliary switch control circuit more control this first auxiliary turn-on time generally with this
Primary side is not turned on the period while originating, and the second auxiliary turn-on time is generally not turned on the period with the primary side and ties simultaneously
Beam.
In a preferred embodiment, when auxiliary switch electric current substantially 0, controlling the auxiliary switch is to be not turned on.
In a preferred embodiment, the power switch control circuit according to the out-put supply, with feedback control, open by the primary side
The primary side turn-on time closed.
Another viewpoint is sayed, present invention provides a kind of conversion control circuits, turn to control a flyback power supply
Circuit is changed, which includes: a transformer, and it includes a first side windings, it is coupled to an input power,
And a secondary side winding, it is coupled to an output node；One primary side switch, is coupled to the first side winding, to switch this
First side winding makes the secondary side winding generate an out-put supply in the output node to convert the input power；And one
Clamp circuit a, comprising: auxiliary switch, including a parasitic diode；And an auxiliary capacitor, connect with the auxiliary switch and
An auxiliary branch is formed, and the auxiliary branch is in parallel with the first side winding；The wherein conversion control circuit, to control this one
Secondary side switch and the auxiliary switch, and convert the input power to generate the out-put supply, wherein the auxiliary switch and this one
Secondary side switch is non-for complementary switching；The conversion control circuit includes: a power switch control circuit, opens to generate a primary side
Control signal is closed to control primary side switch；And an auxiliary switch control circuit, to generate auxiliary switch control letter
Number, and the primary side in primary side switch was not turned in the period, estimated turn-on time according to the one of the parasitic diode, and
One first auxiliary turn-on time of auxiliary switch conducting is controlled, wherein the first auxiliary turn-on time is approximately equal to and overlapping should
Estimate turn-on time.
Another viewpoint is sayed, present invention provides a kind of control method for a flyback power-switching circuit,
Wherein the flyback power-switching circuit includes: a transformer, and it includes a first side windings, is coupled to an input power, with
And a secondary side winding, it is coupled to an output node；One primary side switch, be coupled to the first side winding, to switch this one
Secondary side winding makes the secondary side winding generate an out-put supply in the output node to convert the input power；An and pincers
Position circuit a, comprising: auxiliary switch, including a parasitic diode；And an auxiliary capacitor, it connects and shape with the auxiliary switch
At an auxiliary branch, and the auxiliary branch is in parallel with the first side winding；The wherein conversion control circuit, it is primary to generate one
Side switch control signal and an auxiliary switch control signal, respectively to control primary side switch and the auxiliary switch,
And the input power is converted to generate the out-put supply, wherein the auxiliary switch is non-for complementary switching with primary side switch；It should
Control method is comprised the steps of: to be not turned in the period in a primary side of primary side switch, according to the parasitic diode
One estimates turn-on time, and controls one first auxiliary turn-on time of auxiliary switch conducting, wherein the first auxiliary turn-on time
Approximately equal to and it is overlapped this and estimates turn-on time.
In a preferred embodiment, which also comprises the steps of: is not turned in the period in the primary side, in this
After first auxiliary turn-on time, one second auxiliary turn-on time of auxiliary switch conducting is controlled.
In a preferred embodiment, wherein the second auxiliary turn-on time is determined according at least one following: an electric current
Coherent signal, the input voltage and the output voltage；Wherein the current related signals are relevant at least one following: the output
Electric current, the conducting electric current of primary side switch and the electric current of the first side winding.
In a preferred embodiment, which also comprises the steps of: the wherein first auxiliary turn-on time and should
Second auxiliary turn-on time is not overlapped, and between the first auxiliary turn-on time and the second auxiliary turn-on time, control should
Auxiliary switch is to be not turned on.
In a preferred embodiment, which also comprises the steps of: adjustment the first auxiliary turn-on time, so that
The first auxiliary turn-on time length is substantially the same with the second auxiliary turn-on time length.
In a preferred embodiment, which, which also comprises the steps of:, controls the first auxiliary turn-on time substantially
It is upper to be not turned on the period with the primary side and originate simultaneously, and this second assists turn-on time to be generally not turned on the period with the primary side
Terminate simultaneously.
In a preferred embodiment, which also comprises the steps of: when the auxiliary switch electric current substantially 0
When, controlling the auxiliary switch is to be not turned on.
In a preferred embodiment, which, which also comprises the steps of:, is somebody's turn to do according to the out-put supply with feedback control
One primary side turn-on time of primary side switch.
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 the flyback power-switching circuit with active clamping of prior art；
Fig. 2A and 2B shows the waveform diagram of the flyback power-switching circuit with active clamping of the prior art；
Fig. 3 shows an embodiment schematic diagram of the flyback power-switching circuit with active clamping of the invention；
Fig. 4 shows the waveform diagram corresponding to Fig. 3 embodiment.
Symbol description in figure
1,3 flyback power-switching circuit
10 transformers
20 clamp circuits
30 conversion control circuits
31 power switch control circuits
32 auxiliary switch control circuits
Coss parasitic capacitance
Cr auxiliary capacitor
D2 parasitic diode
IIN input current
Im excitation current
IOUT exports electric current
IP first side winding electric current
ISEN current related signals
Lr leakage inductance
Lm magnetizing inductance
N ratio of winding
OUT output node
S1 primary side switch
S1C primary side switch control signal
S2 auxiliary switch
S2C auxiliary switch controls signal
The Td auxiliary empty stagnant time
TONA turn-on time
TOD2 turn-on time
TOFF1 is not turned on the time
TON2, TON2 ' turn-on time
VI input voltage
VO output voltage
W1 first side winding
W2 secondary side winding
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.
Referring to Fig. 3, being as shown in the figure a kind of reality of the flyback power-switching circuit with active clamping of the invention
It applies example (flyback power-switching circuit 3), flyback power-switching circuit 3 includes transformer 10, primary side switch S1, clamp electricity
Road 20 and conversion control circuit 30.Wherein transformer 10 includes first side winding W1, is coupled to an input power, Yi Jiyi
Secondary side winding W2 is coupled to an output node OUT, and wherein the input power includes an input voltage VI and an input current
IIN.Primary side switch S1 is coupled to first side winding W1, to switch first side winding W1 to convert the input power, and
Secondary side winding W2 is set to generate an out-put supply in output node OUT to supply load 40, wherein out-put supply includes output electricity
Press a VO and output current IO UT.
Please continue to refer to Fig. 3, clamp circuit 20 includes auxiliary switch S2 and auxiliary capacitor Cr, with auxiliary switch
S2 connects and forms an auxiliary branch, as shown, auxiliary branch is in parallel with first side winding W1.Conversion control circuit 30 includes
Power switch control circuit 31 and auxiliary switch control circuit 32, wherein power switch control circuit 31 is to according to primary side
Feedback or secondary side feedback system and generate primary side switch control signal S1C, auxiliary switch control circuit 32 then generates auxiliary
Switch control signal S2C, respectively to control primary side switch S1 and auxiliary switch S2, and it is defeated to generate to convert input power
Power supply out.
There is a parasitic diode D2 please continue to refer to Fig. 3, auxiliary switch S2, wherein auxiliary switch control circuit 32 is in one
The primary side of secondary side switch S1 is not turned in period TOFF1, according to the turn-on time of estimating of parasitic diode D2, and controls auxiliary
One first auxiliary turn-on time TON2 of switch S2 conducting, wherein the first auxiliary turn-on time TON2 is approximately equal to and is overlapped in post
Raw diode D2's estimates turn-on time, to effectively eliminate the Qrr effect of parasitic diode D2, or reduces by parasitic diode
Added power dissipation caused by the forward voltage of D2.
It should be noted that: although the first auxiliary turn-on time TON2 is made to be exactly equal to and be overlapped in parasitic diode D2
Estimate turn-on time, but because matching mutual between error part of circuit component itself is not necessarily ideal or letter
Number transmitting delay, therefore actually generate first auxiliary turn-on time TON2 may and absolutely accurately can not be equal to and be overlapped
In the turn-on time of estimating of parasitic diode D2, and there is acceptable error, the meaning of this " generally " i.e. above-mentioned, similarly hereinafter.
Please continue to refer to Fig. 3, in one embodiment, auxiliary switch control circuit 32 is when primary side switch S1 is not turned on
In another a period of time (the second auxiliary turn-on time TON2 '), control auxiliary switch S2 carries out another conducting, makes first side winding
The energy leakage inductance Lr and/or magnetizing inductance Lm of W1 stored when primary side switch S1 is connected, can be released by auxiliary branch
And be stored among auxiliary capacitor Cr, in addition, before primary side switch S1 conducting, it can be by being stored in auxiliary capacitor Cr
In energy, discharge the parasitic capacitance Coss of primary side switch S1, in one embodiment, the conducting of auxiliary switch S2 may make
It is zero voltage switching when primary side switch S1 is connected.
In one embodiment, auxiliary switch control circuit 32 adjusts leading for auxiliary switch S2 according at least one following
Logical TON2 ': one current related signals ISEN of time, input voltage VI and output voltage VO；In one embodiment, according to above-mentioned
The adjustment of parameter, when primary side switch S1 may make to be connected, current input terminal LX (is coupled with current output terminal in the present embodiment
Primary side grounding point) voltage difference (VDS1 in such as figure) substantially 0, and reach zero voltage switching；The wherein electric current
Coherent signal ISEN is relevant at least one following: output current IO UT, the conducting electric current IDS1 of primary side switch, and primary
The electric current IP of side winding W1；In one embodiment, current related signals ISEN can by sense primary side switch S1 VDS1, one
The conducting electric current IDS1 of secondary side switch S1 or the cross-pressure of current sensing resistor and obtain.
Please refer to Fig. 4, display corresponds to the waveform diagram of Fig. 3 embodiment in figure, and in one embodiment, first is auxiliary
It is originated after helping turn-on time TON2 to be next to the turn-on time of primary side switch S1, it is, the first auxiliary turn-on time
TON2 is generally not turned on period TOFF1 with the primary side and originates simultaneously.In one embodiment, auxiliary switch control circuit 32 is proper
Before primary side switch S1 switchs to conducting, second auxiliary turn-on time TON2 ' is connected in control auxiliary switch S2, it is, the
Two auxiliary turn-on time TON2 ', which are generally not turned on the period simultaneously with the primary side, to be terminated.In the present embodiment, do not led in primary side
In logical period TOFF1, the first auxiliary turn-on time TON2 is prior to the second auxiliary turn-on time TON2 '.In addition, in implementing one,
Between conducting in primary side switch S1 is connected with the first time of auxiliary switch S2 or is connected for second, there can be the empty stagnant time
(dead time) Td, to ensure that primary side switch S1 and auxiliary switch S2 will not be simultaneously turned on and cause short circuit current.
Please continue to refer to Fig. 4, as shown, in one embodiment, the first auxiliary turn-on time TON2 is led with the second auxiliary
Logical time TON2 ' is not overlapped, and between the first auxiliary turn-on time TON2 and the second auxiliary turn-on time TON2 ', auxiliary is opened
Closing S2 is to be not turned on, and thus can be reduced around electric current.Certainly, in other embodiments, the first auxiliary turn-on time TON2 and the
Two auxiliary turn-on time TON2 ' can also be overlapped, especially higher or primary side is not turned on the period in such as, but not limited to frequency
In the case that TOFF1 is shorter；As long as the first auxiliary turn-on time TON2 is to estimate turn-on time according to parasitic diode D2
And determine, that is, meet spirit of the invention.Further, since charge conservation, therefore, when estimating conducting of aforementioned parasitic diode D2
Between length generally can be equal to second auxiliary turn-on time TON2 ', therefore, according to the present invention, one implement in, auxiliary switch control
First auxiliary of the adjustment of circuit 32 turn-on time TON2 processed, so that the length of the first auxiliary turn-on time TON2 is connected with the second auxiliary
The length of time TON2 ' is substantially the same, and the first auxiliary turn-on time TON2 can so be made to be approximately equal to and be overlapped in post
Raw diode D2's estimates turn-on time, to effectively eliminate the Qrr effect of parasitic diode D2, or reduces by parasitic diode
Added power dissipation caused by the forward voltage of D2.In addition, in one embodiment, when auxiliary switch S2 electric current generally
When being 0, it is to be not turned on that auxiliary switch control circuit 32, which controls auxiliary switch S2, thus can ensure that reduction around electric current.
Please continue to refer to Fig. 4, for another viewpoint, in one preferably implementation, according to the present invention, in primary side switch S1
Switch to after being not turned on, auxiliary switch control circuit 32 controls auxiliary switch S2 conducting for the first time (corresponding first auxiliary turn-on time
TON2 after), and switch to be not turned on after the first auxiliary turn-on time TON2, then, before primary side switch S1 switchs to conducting, control
Second of auxiliary switch S2 conducting (corresponding second auxiliary turn-on time TON2 ') processed, and the first auxiliary turn-on time TON2 is adjusted,
So that the length of the first auxiliary turn-on time TON2 and the length of the second auxiliary turn-on time TON2 ' are substantially the same, it is worth note
Meaning, within the TON2 period in figure, auxiliary capacitor electric current ICr is connected by auxiliary switch S2, rather than parasitic two poles
Pipe D2, thus the Qrr effect of parasitic diode D2 can be effectively eliminated, or reduce and made by the forward voltage of parasitic diode D2
At added power dissipation.
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 can also be with combined application；Lift wherein an example, and " a primary side be not turned in the period be connected it is secondary " can be with " first and the
Two auxiliary turn-on times are identical " and the combination such as " controlled when auxiliary switch electric current substantially 0 auxiliary switch be not turned on "
Using.In addition, under same spirit of the invention, it may occur to persons skilled in the art that various equivalence changes and various groups
It closes.For example, adjustment the first auxiliary turn-on time TON2, so that the length of the first auxiliary turn-on time TON2 is connected with the second auxiliary
The length of time TON2 ' is substantially the same, wherein it is aforementioned that the length of the second auxiliary turn-on time TON2 ' is not limited to the application
Deciding means in embodiment, in other embodiments, the second auxiliary turn-on time are also possible to such as fixation in the prior art
Turn-on time, as long as the length generally phase of the length of the first auxiliary turn-on time TON2 and the second auxiliary turn-on time TON2 '
Together, that is, meet spirit of the invention.In another example " carrying out processing or operation alleged by the present invention according to certain signal or generating certain output
As a result ", it is not limited to itself the signal be carried out Voltage to current transducer, Current Voltage also comprising when necessary according to the signal
Conversion and/or ratio conversion etc. carry out processing according to the signal after conversion later or operation generate certain output result.Thus may be used
Know, under same spirit of the invention, it may occur to persons skilled in the art that various equivalence changes 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 (24)
1. a kind of flyback power-switching circuit, characterized by comprising:
One transformer, it includes a first side windings, are coupled to an input power and a secondary side winding, it is defeated to be coupled to one
Egress；
One primary side switch, is coupled to the first side winding, to switch the first side winding to convert the input power, and makes
The secondary side winding generates an out-put supply in the output node；
One clamp circuit, comprising:
One auxiliary switch, including a parasitic diode；And
One auxiliary capacitor connects with the auxiliary switch and forms an auxiliary branch, and the auxiliary branch and the first side winding
It is in parallel；And
One conversion control circuit to control primary side switch and the auxiliary switch, and converts the input power to generate
The out-put supply, wherein the auxiliary switch is non-for complementary switching with primary side switch；The conversion control circuit includes:
One power switch control circuit, to generate a primary side switch control signal to control primary side switch；And
One auxiliary switch control circuit, to generate auxiliary switch control signal, and in a primary side of primary side switch
It is not turned in the period, estimates turn-on time according to the one of the parasitic diode, and control one first auxiliary of auxiliary switch conducting
Turn-on time, wherein the first auxiliary turn-on time is approximately equal to and is overlapped this and estimates turn-on time.
2. flyback power-switching circuit according to claim 1, wherein the auxiliary switch control circuit, it is primary in this
Side was not turned in the period, after the first auxiliary turn-on time, more controlled one second auxiliary turn-on time of auxiliary switch conducting.
3. flyback power-switching circuit according to claim 2, wherein the auxiliary switch control circuit according to it is following extremely
It is one of few and determine the second auxiliary turn-on time a: current related signals, the input voltage and the output voltage；Wherein should
Current related signals are relevant at least one following: the output electric current, the conducting electric current and the primary side of primary side switch
The electric current of winding.
4. flyback power-switching circuit according to claim 2, wherein the first auxiliary turn-on time is second auxiliary with this
Turn-on time is helped not to be overlapped, and between the first auxiliary turn-on time and the second auxiliary turn-on time, which is
It is not turned on.
5. flyback power-switching circuit according to claim 2, wherein the auxiliary switch control circuit more adjust this
One auxiliary turn-on time, so that the first auxiliary turn-on time length is substantially the same with the second auxiliary turn-on time length.
6. flyback power-switching circuit according to claim 2, wherein the auxiliary switch control circuit more control this
One auxiliary turn-on time is generally not turned on the period with the primary side and originates simultaneously, and the second auxiliary turn-on time generally with
The primary side is not turned on the period while terminating.
7. flyback power-switching circuit according to claim 1, wherein when auxiliary switch electric current substantially 0,
Controlling the auxiliary switch is to be not turned on.
8. flyback power-switching circuit according to claim 1, wherein the power switch control circuit is according to the output
The primary side turn-on time that power supply is switched with the feedback control primary side.
9. a kind of conversion control circuit, which is characterized in that control a flyback power-switching circuit, which turns
Changing circuit includes: a transformer, and it includes a first side windings, is coupled to an input power and a secondary side winding, coupling
In an output node；One primary side switch, is coupled to the first side winding, to switch the first side winding to convert the input
Power supply, and the secondary side winding is made to generate an out-put supply in the output node；An and clamp circuit a, comprising: auxiliary is opened
It closes, including a parasitic diode；And an auxiliary capacitor, it connects with the auxiliary switch and forms an auxiliary branch, and this is auxiliary
Help branch in parallel with the first side winding；The wherein conversion control circuit is opened to control primary side switch and the auxiliary
It closes, and converts the input power to generate the out-put supply, wherein the auxiliary switch is non-for complementary switching with primary side switch；
The conversion control circuit includes:
One power switch control circuit, to generate a primary side switch control signal to control primary side switch；And
One auxiliary switch control circuit, to generate auxiliary switch control signal, and in a primary side of primary side switch
It is not turned in the period, estimates turn-on time according to the one of the parasitic diode, and control one first auxiliary of auxiliary switch conducting
Turn-on time, wherein the first auxiliary turn-on time is approximately equal to and is overlapped this and estimates turn-on time.
10. conversion control circuit according to claim 9, wherein the auxiliary switch control circuit is not led in the primary side
In the logical period, after the first auxiliary turn-on time, one second auxiliary turn-on time of auxiliary switch conducting is more controlled.
11. conversion control circuit according to claim 10, wherein the auxiliary switch control circuit according to it is following at least it
One and determine this second auxiliary turn-on time: a current related signals, the input voltage and the output voltage；The wherein electric current
Coherent signal is relevant at least one following: the output electric current, the conducting electric current and the first side winding of primary side switch
Electric current.
12. conversion control circuit according to claim 10, wherein the first auxiliary turn-on time is led with second auxiliary
The logical time is not overlapped, and between the first auxiliary turn-on time and the second auxiliary turn-on time, which is not lead
It is logical.
13. conversion control circuit according to claim 10, wherein it is first auxiliary that the auxiliary switch control circuit more adjusts this
Turn-on time is helped, so that the first auxiliary turn-on time length is substantially the same with the second auxiliary turn-on time length.
14. conversion control circuit according to claim 10, wherein it is first auxiliary that the auxiliary switch control circuit more controls this
Help turn-on time to be generally not turned on the period with the primary side to originate simultaneously, and the second auxiliary turn-on time generally with this one
Secondary side is not turned on the period while terminating.
15. conversion control circuit according to claim 9, wherein when auxiliary switch electric current substantially 0, control
The auxiliary switch is to be not turned on.
16. conversion control circuit according to claim 9, wherein the power switch control circuit is according to the out-put supply
The primary side turn-on time switched with the feedback control primary side.
17. a kind of control method for a flyback power-switching circuit, which is characterized in that the flyback power-switching circuit
It include: a transformer, it includes a first side windings, are coupled to an input power and a secondary side winding, it is defeated to be coupled to one
Egress；One primary side switch, is coupled to the first side winding, to switch the first side winding to convert the input power,
And the secondary side winding is made to generate an out-put supply in the output node；An and clamp circuit a, comprising: auxiliary switch, packet
Include a parasitic diode；And an auxiliary capacitor, it connects with the auxiliary switch and forms an auxiliary branch, and the auxiliary branch
It is in parallel with the first side winding；The control method comprises the steps of:
Primary side switch and the auxiliary switch are controlled, and converts the input power to generate the out-put supply, wherein this is auxiliary
Help switch non-for complementary switching with primary side switch；And
It is not turned in the period in a primary side of primary side switch, estimates turn-on time according to the one of the parasitic diode, and
One first auxiliary turn-on time of auxiliary switch conducting is controlled, wherein the first auxiliary turn-on time is approximately equal to and overlapping should
Estimate turn-on time.
18. control method according to claim 17, wherein also comprise the steps of: and be not turned on the period in the primary side
It is interior, after the first auxiliary turn-on time, control one second auxiliary turn-on time of auxiliary switch conducting.
19. control method according to claim 18, wherein this second auxiliary turn-on time according at least one following and
It determines: a current related signals, the input voltage and the output voltage；Wherein the current related signals be relevant to it is following at least
One of: the output electric current, the conducting electric current of primary side switch and the electric current of the first side winding.
20. control method according to claim 18, wherein when also comprising the steps of: wherein the first auxiliary conducting
Between with this second auxiliary turn-on time it is not be overlapped, and in this first auxiliary turn-on time and this second auxiliary turn-on time between,
Controlling the auxiliary switch is to be not turned on.
21. control method according to claim 18, wherein when also comprising the steps of: adjustment the first auxiliary conducting
Between, so that the first auxiliary turn-on time length is substantially the same with the second auxiliary turn-on time length.
22. control method according to claim 18, wherein when also comprising the steps of: control the first auxiliary conducting
Between be generally not turned on the period with the primary side and originate simultaneously, and the second auxiliary turn-on time is not led with the primary side generally
The logical period terminates simultaneously.
23. control method according to claim 17, wherein also comprise the steps of: when the auxiliary switch electric current substantially
When being above 0, controlling the auxiliary switch is to be not turned on.
24. control method according to claim 17, wherein also comprise the steps of: according to the out-put supply to feed back
Control a primary side turn-on time of primary side switch.
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| CN201711017765.6A CN109713904B (en) | 2017-10-26 | 2017-10-26 | Flyback power conversion circuit and conversion control circuit and control method thereof |
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| CN112311239A (en) * | 2019-07-30 | 2021-02-02 | 力林科技股份有限公司 | Voltage conversion device |
| CN112787513A (en) * | 2019-11-11 | 2021-05-11 | 立锜科技股份有限公司 | Flyback power converter and active clamping buffer thereof |
| TWI741596B (en) * | 2020-05-11 | 2021-10-01 | 加拿大商萬國半導體國際有限合夥公司 | Flyback converter, control circuit thereof, and associated control method |
| US11336185B2 (en) | 2020-05-11 | 2022-05-17 | Alpha And Omega Semiconductor International Lp | Flyback converter, control circuit thereof, and associated control method |
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| TWI741596B (en) * | 2020-05-11 | 2021-10-01 | 加拿大商萬國半導體國際有限合夥公司 | Flyback converter, control circuit thereof, and associated control method |
| US11336185B2 (en) | 2020-05-11 | 2022-05-17 | Alpha And Omega Semiconductor International Lp | Flyback converter, control circuit thereof, and associated control method |
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|---|---|
| CN109713904B (en) | 2020-11-24 |
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