CN108667302A - A kind of isolated switching circuit and its control method - Google Patents
A kind of isolated switching circuit and its control method Download PDFInfo
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- CN108667302A CN108667302A CN201810258040.4A CN201810258040A CN108667302A CN 108667302 A CN108667302 A CN 108667302A CN 201810258040 A CN201810258040 A CN 201810258040A CN 108667302 A CN108667302 A CN 108667302A
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- time information
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Power Engineering (AREA)
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Abstract
The invention discloses a kind of isolated switching circuit and its control methods, the present invention carries out the control and adjusting on former secondary side using first time information as feature, the information on former secondary side is transmitted without optocoupler, primary side identifies the first time by detecting the voltage at master power switch pipe both ends, secondary side then passes through sampling and outputting voltage or/and output current, it is compared with corresponding reference signal, obtains the first control signal of characterization first time information.Primary side can adjust second time and peak point current according to the first time information, when the first control signal is higher than third threshold value, then the isolated switching circuit works in fixed frequency, under the fixed frequency, the isolated switching circuit enters continuous conduction mode or discontinuous conduction mode.The present invention carries out the isolation transmission of former secondary side signal without optocoupler, reduces circuit cost, the parasitic diode time of afterflow of synchronous rectifier is identified and is controlled as feature, controls and adjusts and is more accurate.
Description
Technical field
The present invention relates to a kind of power electronics field, more particularly to a kind of isolated switching circuit and its controlling party
Method.
Background technology
Synchronous rectification is to use the lower power MOSFET of on state resistance, to replace rectifier diode to reduce rectifier loss
A kind of method, be used in isolated switching circuit.The isolated switching circuit of the prior art, generally comprises master power switch
Pipe, transformer and synchronous rectifier are controlled the conducting state of master power switch pipe by control circuit, by synchronous commutating control circuit
It controls synchronous rectifier and realizes synchronous rectification.In isolated switching circuit, former secondary side feedback letter is often realized using optocoupler
Number transmission.
As shown in Figure 1, switch flyback switch circuit of the prior art based on synchronous rectification is illustrated, by sampling the defeated of secondary side
Go out voltage, secondary side signal is transferred to primary side through optocoupler, and received by control circuit, the control circuit is passed according to by optocoupler
Defeated feedback signal correspondingly controls the action of master power switch pipe.The former secondary side of isolated switching circuit is realized using optocoupler
Signal transmission, although isolation can be solved the problems, such as, there are still be added to the relatively low technical problem of this and precision.
Invention content
The object of the present invention is to provide a kind of isolated switching circuit and its control method, solve it is of the existing technology at
This high technical problem low with precision is conducive to accurately realize control to improve the accuracy of detection of feedback signal.
To achieve the above object, the present invention provides a kind of isolated switching circuits, including master power switch pipe, transformer
And synchronous rectifier, the transformer include primary side winding and vice-side winding, the master power switch pipe and the primary side around
Group connection, the synchronous rectifier are connect with the vice-side winding；
Secondary side control circuit receives the first control signal of characterization first time information, the secondary side control circuit and institute
The control terminal connection of synchronous rectifier is stated, the first control signal is used to control the shutdown of synchronous rectifier；Described
One temporal information is the time of afterflow or synchronous rectifier of parasitic diode after synchronous rectifier shutdown in a switch periods
The time of afterflow of parasitic diode is opened with synchronous rectifier formed by the time that the moment terminates to secondary current afterflow after shutdown
Ratio；
The first time information is detected from primary side, the detection signal for characterizing the first time information is obtained, according to institute
The detection signal for stating characterization first time information, is adjusted the state of master power switch pipe through primary-side-control circuit；
When the first control signal is higher than third threshold value, then the isolated switching circuit works in fixed frequency,
Under the fixed frequency, the isolated switching circuit enters continuous conduction mode or discontinuous conduction mode.
Optionally, the first control signal is obtained by following manner：Sample the output of the isolated switching circuit
Voltage or/and output current obtain sampled voltage signal, and the sampled voltage signal is compared with the first reference signal,
Obtain the first control signal of characterization first time information.
Optionally, according to the detection signal of the characterization first time information, the second time or/and primary side winding are adjusted
Peak point current, second time are to terminate from current switch period to next switch periods master power switch pipe turn-on instant
Time or two switch periods start times between interval time.
Optionally, described to refer to from the primary side detection first time information, by directly detecting or passing through auxiliary winding
The voltage for detecting master power switch pipe both ends obtains characterizing described the according to the variation characteristic of master power switch pipe both end voltage
The detection signal of one temporal information.
Optionally, the first time information of current switch period is more than the first time information of a upper switch periods, then
So that second time accordingly increases, or/and, reduce the peak point current of primary side winding；The first time of current switch period
Information is less than the first time information of a upper switch periods, then so that second time accordingly reduces, or/and, it improves former
The peak point current of side winding.
Optionally, the first time information of current switch period is more than the first time information of a upper switch periods, then
So that second time accordingly reduces, or/and, improve the peak point current of primary side winding；The first time of current switch period
Information is less than the first time information of a upper switch periods, then so that second time accordingly reduces, or/and, it improves former
The peak point current of side winding.
Optionally, the peak point current of second time or/and primary side winding increase with the increase of first time or
Reduce.
Optionally, when the first time information is more than first threshold or less than second threshold, then the main work(is controlled
Rate switching tube is held off until being waken up or making the switching frequency of isolated switching circuit to be maintained detection frequency, institute again
The detection frequency stated, if changing, adjusts the work of isolated switching circuit for periodically judging whether load changes
Operation mode.
Optionally, will terminate from current switch period to the time of next switch periods master power switch pipe turn-on instant or
Interval time between two switch periods start times is as the second time；It is superimposed disturbing signal on second time,
So that switching circuit is worked in and tremble frequency pattern, alternatively, when switching frequency is preferably minimized, by extending second time, with into
One step reduces switching frequency, and switching circuit is made to work in intermittent mode.
Optionally, by the turn-on instant of the master power switch pipe of the next switch periods of adjusting come when adjusting described second
Between；The peak point current is adjusted by the turn-on time of the master power switch pipe of the next switch periods of adjusting.
Optionally, by the electric current of the synchronized rectifying tube of sample streams, current sampling signal is obtained, by the current sample
Signal is compared with the first control signal, with the turn-off time of the determination synchronous rectifier, to adjust described
One temporal information.
Optionally, the isolated switching circuit further includes primary-side-control circuit, the primary-side-control circuit and institute
The control terminal connection of master power switch pipe is stated, the primary-side-control circuit includes first time information detection and adjusts electric
Road, the adjusting circuit include the second time adjustment circuit or/and peak current regulation circuit, and the adjusting circuit receives
The first time information detection output characterizes the detection signal of the first time information, passes through the second time adjustment electricity
Road adjust second time or/pass through the peak current regulation circuit and adjust the peak point current.
The present invention also provides a kind of control method of isolated switching circuit,
The isolated switching circuit includes master power switch pipe, transformer and synchronous rectifier, the transformer packet
Include primary side winding and vice-side winding, the master power switch pipe is connect with the primary side winding, the synchronous rectifier with
The vice-side winding connection,
The control method includes the following steps：Secondary side control circuit receives the first control of characterization first time information
Signal, the secondary side control circuit are connect with the control terminal of the synchronous rectifier, and the first control signal is for controlling
The shutdown of synchronous rectifier processed；The first time information is parasitic two poles after synchronous rectifier shutdown in a switch periods
The time of afterflow of parasitic diode opens the moment to pair with synchronous rectifier after time of afterflow or the synchronous rectifier shutdown of pipe
Ratio formed by the time that side current stream terminates；
The first time information is detected from primary side, the detection signal for characterizing the first time information is obtained, according to institute
The detection signal for stating characterization first time information, is adjusted the state of master power switch pipe through primary-side-control circuit；
When the first control signal is higher than third threshold value, then the isolated switching circuit works in fixed frequency,
Under the fixed frequency, the isolated switching circuit enters continuous conduction mode or discontinuous conduction mode.
Optionally, the first control signal is obtained by following manner：Sample the output of the isolated switching circuit
Voltage or/and output current obtain sampled voltage signal, and the sampled voltage signal is compared with the first reference signal,
Obtain the first control signal of characterization first time information.
Optionally, according to the detection signal of the characterization first time information, the second time or/and primary side winding are adjusted
Peak point current, second time are to terminate from current switch period to next switch periods master power switch pipe turn-on instant
Time or two switch periods start times between interval time.
Optionally, described to refer to from the primary side detection first time information, by directly detecting or passing through auxiliary winding
The voltage for detecting master power switch pipe both ends obtains characterizing described the according to the variation characteristic of master power switch pipe both end voltage
The detection signal of one temporal information.
Optionally, the first time information of current switch period is more than the first time information of a upper switch periods, then
So that second time accordingly increases, or/and, reduce the peak point current of primary side winding；The first time of current switch period
Information is less than the first time information of a upper switch periods, then so that second time accordingly reduces, or/and, it improves former
The peak point current of side winding.
Optionally, will terminate from current switch period to the time of next switch periods master power switch pipe turn-on instant or
Interval time between two switch periods start times is as the second time；It is superimposed disturbing signal on second time,
So that switching circuit is worked in and tremble frequency pattern, alternatively, when switching frequency is preferably minimized, by extending second time, with into
One step reduces switching frequency, and switching circuit is made to work in intermittent mode.
Compared with prior art, the technical solution of the present invention has the following advantages：The present invention using first time information as
Feature carries out the control and adjusting on former secondary side, and without the information on the former secondary side of optocoupler transmission, primary side is by detecting master power switch pipe
The voltage at both ends identifies the first time information, and secondary side is then by sampling and outputting voltage or/output current, with corresponding ginseng
It examines signal to be compared, obtains the first control signal of characterization first time information.Primary side can be according to the first time information
To adjust second time and peak point current.The present invention carries out the isolation transmission of former secondary side signal without optocoupler, reduces
Circuit cost, while the parasitic diode time of afterflow of synchronous rectifier being identified and being controlled as feature, it controls and adjusts
Section is more accurate.
Description of the drawings
Fig. 1 is the structure principle chart of prior art switch flyback switch circuit；
Fig. 2 is the work wave schematic diagram of the isolated switching circuit of the present invention；
Fig. 3 is the structure principle chart of the isolated switching circuit of the present invention；
Fig. 4 is the structure diagram of primary-side-control circuit；
Fig. 5 is the variation tendency oscillogram of first time and first control signal.
Specific implementation mode
The preferred embodiment of the present invention is described in detail below in conjunction with attached drawing, but the present invention is not restricted to these
Embodiment.The present invention covers any replacement made in the spirit and scope of the present invention, modification, equivalent method and scheme.
In order to make the public have thorough understanding to the present invention, it is described in detail in following present invention preferred embodiment specific
Details, and description without these details can also understand the present invention completely for a person skilled in the art.
The present invention is more specifically described by way of example with reference to attached drawing in the following passage.It should be noted that attached drawing is adopted
Use with more simplified form and non-accurate ratio, only to it is convenient, lucidly aid in illustrating the embodiment of the present invention
Purpose.
As shown in Fig. 2, illustrating the work wave of the isolated switching circuit of the present invention, including the both ends master power switch pipe M1
Voltage VDSWith the waveform of former secondary current I.It is a switch periods from 0 to T, is active rate switching tube M1's from 0 to t0 moment
Turn-on time, during being connected due to active rate switching tube M1, the impedance very little of its own, so the voltage at its both ends is similar to 0,
Within this period, the electric current of primary side increases to peak point current Ip from 0.At the t0 moment, the M1 shutdowns of master power switch pipe, primary current
It is zero, the synchronous rectifier M2 conductings on secondary side, secondary current is begun to decline from peak point current Ip at this time, it should be noted that secondary side
The Ip sizes of electric current Ip and primary current can be the same or different, in fig. 2, can be in order to illustrate the convenience with signal
It is equivalent to the electric current on one side, i.e., equivalent exciting current, so regard the two as identical, but secondary current Ip and original
Turn ratio when the Ip sizes of electric current are mainly secondary by original determines.In t0~t1 periods, synchronous rectifier M2 conductings are secondary at this time
Side electric current declines, at the t1 moment, synchronous rectifier M2 shutdowns, and the parasitic diode (also becoming body diode) of synchronous rectifier M2
Start afterflow, secondary current continues to reduce, and at the t2 moment, secondary current is reduced to 0, in t1~t2 periods as at the first time
T1, within this period, voltage VDSWith stronger identification, detection is more accurate, for example, can be by detecting rising edge
The detection signal of characterization first time T1 is relatively accurately obtained with the mode of failing edge.T2~T time Duan Ze characterizes second
Time T2 terminates from parasitic diode afterflow to the turn-on instant of next switch periods master power switch pipe.Although this implementation
The detailed description of example is by taking first time T1 as an example, and still, the first time T1 is first time information of the present invention
A kind of forms of characterization, can also be with " synchronous rectifier opens the time that moment to secondary current is reduced to zero in the present embodiment
Formed ratio " is used as the first time information.
It, can be electric by the output voltage or/output that sample isolated switching circuit on the secondary side of isolated switching circuit
Stream, obtains sampled voltage signal, the sampled voltage signal is compared with the first reference signal, obtains characterization at the first time
First control signal Vc, the first control signal is acted on into synchronous rectifier M2, can with automatic adjusument at the first time
T1.Load becomes weight, and then the first time T1 reduces；The then first time T1 that lightens is loaded to increase.The first control letter
The variation tendency of number Vc and the first time T1 are identical or opposite.For the ease of signal, although only illustrating to sample in figure
The case where output voltage, it is also possible to sampled output current；Further, it is also possible to generate the first control by signal set in addition
Signal processed.With first control signal Vc, come in the case of characterizing first time, the first control signal is higher than third threshold value
When, i.e. Vc rises to a certain extent, and the working frequency of isolated switching circuit no longer changes, therefore the isolated switching circuit work
Make in fixed frequency, under the fixed frequency, the isolated switching circuit enters continuous conduction mode (CCM) or Discontinuous Conduction
Which kind of working frequency is pattern (DCM) specifically enter, also related to the factors such as peak point current, input voltage and output voltage, inputs
Voltage influence inductive current rises to the slope of peak value, and output voltage affects the slope of inductive current decline.Described first
After control signal Vc reaches third threshold value, when continuing to rise and reaching four threshold values, then the peak point current of inductance is fixed, i.e., at this time
Switching frequency and peak point current are each attached to particular value.
The information on former secondary side is transmitted in the control and adjusting that former secondary side is carried out using first time T1 as feature without optocoupler,
Primary side identifies that the first time T1, secondary side then pass through sampling and outputting voltage by detecting the voltage at master power switch pipe both ends
It is compared with the first reference signal Vref1, obtains the first control signal Vc of characterization first time.Primary side can be according to described
One time adjusted second time T2 and peak point current Ip.
The first time T1 of current switch period is more than the first time T1 of a upper switch periods, then so that described second
Time, T2 accordingly increased, or/and, reduce the peak point current Ip of primary side winding；The first time T1 of current switch period is less than upper
The first time T1 of one switch periods, then so that the second time T2 is accordingly reduced, or/and, improve the peak of primary side winding
It is worth electric current Ip.Certainly, former secondary side " can also arrange " first time T1 and the second time T2, peak point current Ip in the presence of and above-mentioned phase
Anti- association, i.e. the first time T1 of current switch period are more than the first time T1 of a upper switch periods, then so that described
Second time T2 accordingly reduces, or/and, improve the peak point current of primary side winding；The first time T1 of current switch period is less than
The first time information of a upper switch periods, then so that second time accordingly reduces, or/and, improve primary side winding
Peak point current.Thus, it can be seen that it can be that former secondary side identifies " medium " that first time T1, which is one, be thus not necessarily to former secondary side into
Row first time information is transmitted, " agreement " the consistent association with the second time T2, peak point current Ip at the first time of former pair side,
It can be achieved.For the weight and first control signal or the relationship of first time information of load, with error amplifier EA positive and negative terminals
Access signal it is related, load lightens, and according to setting, first control signal or first time information can increase or subtract
It is small, the change weight of load, then on the contrary.
Above only with regard to the second time T2 be from current switch period terminate to next switch periods master power switch pipe be connected
The time at moment is described in detail, but as shown, T2 ' characterize two switch periods start times between interval time,
Also it was used as the second time.
For the present invention, it is identified as feature using the first time, and for controlling or regulating main work(
Rate switching tube, so that it may basic the technical issues of solving the application, and the second time and peak value are carried out according to the first time
The adjusting of electric current belongs to a kind of specific application, and further solves technical problem.In addition, there is also tremble frequency pattern by the present invention
With discontinuous operation pattern (burst mode), described trembles frequency pattern, one disturbance letter of superposition as on second time
Number so that switching frequency is shaken, and can be attached to and solve the problems, such as EMI；The discontinuous operation pattern is to load very
In the case of light, switching frequency has been reduced to minimum, for example, 22KHz or so, enters discontinuous operation pattern at this time, makes switch frequency
Rate is down to lower range, for example, 300Hz or so, so more power saving.
Since there are two kinds of variation tendencies for first time information, it may increase and reach first threshold, arrival can also be reduced
Second threshold, described when the first time information is more than first threshold or less than second threshold, the second time has been at this time
It can not further reduce, i.e., switching frequency also reaches " switching frequency has been reduced to minimum " described above, then controls institute
It states master power switch pipe to be held off until being waken up again, the wake-up can be connected by the synchronous rectifier on secondary side
It realizes, or the switching frequency of isolated switching circuit is made to be maintained detection frequency, the detection frequency can be arranged
1000Hz is hereinafter, the detection frequency, if changing, adjusts isolated for periodically judging whether load changes
The operating mode of switching circuit.
As shown in figure 3, the structural principle of the isolated switching circuit of the present invention is illustrated, for inverse excitation type converter.It is described
Isolated switching circuit include master power switch pipe M1, transformer and synchronous rectifier M2, the transformer include primary side around
Group L1 and vice-side winding L2, the master power switch pipe M1 are connect with the primary side winding L1, the synchronous rectifier M2
It is connect with the vice-side winding L2；
The output voltage Vout that the isolated switching circuit is sampled by the bleeder circuit being made of resistance R1 and R2, obtains
To voltage sampling signal VFB, by the voltage sampling signal VFBIt is compared with the first reference signal Vref1, obtains characterization
The first control signal Vc, the first control signal Vc of one time T1 is connect with secondary side control circuit, secondary side control
Circuit processed is connect with the control terminal of the synchronous rectifier.
The present embodiment using auxiliary winding La with it is described transformer coupled, and the partial pressure by being made of resistance R3 and R4 is electric
Road, the voltage V at sampling master power switch pipe both endsDS, because source electrode is grounded so the i.e. voltage of drain terminal D, obtains signal V1.The letter
Number V1 obtains the detection signal for characterizing the first time T1 by the judgement of rising edge and failing edge, according to the characterization the
The detection signal of one time adjusts the peak point current of the second time or/and primary side winding, and second time is from secondary side electricity
Stream be reduced to zero to next switch periods master power switch pipe turn-on instant time.In addition to this, leakage can also directly be sampled
The voltage of D is held to obtain the signal V1 of characterization master power switch pipe both end voltage.
Although the present embodiment by taking inverse excitation type converter as an example, can be suitable for most of isolated switching circuits, no
It is limited by example is carried out.
As shown in figure 4, illustrating the structure diagram of primary-side-control circuit.The primary-side-control circuit and the main power
The control terminal of switching tube connects, and the primary-side-control circuit includes first time detection circuit and adjusting circuit, the adjusting
Circuit includes the second time adjustment circuit or/and peak current regulation circuit, and the adjusting circuit receives the first time
Detection circuit output characterizes the detection signal V2 of the first time, when adjusting described second by the second time adjustment circuit
Between or/pass through the peak current regulation circuit and adjust the peak point current.The adjusting circuit is only listed in fig. 2
Including the second time adjustment circuit and the case where peak current regulation circuit.Meanwhile primary-side-control circuit further includes driving circuit,
It is connect with the control terminal of master power switch pipe M1 by driving circuit.
As shown in figure 5, illustrating trend charts of the first time T1 with first control signal Vc.It is clear in order to illustrate in figure
Chu is set as linear change, but actually both can be linear, or and it is non-linear, a kind of trend is only illustrated in figure.Together
When, what is anticipated as shown in the figure is the increase with Vc, and first time, T1 accordingly reduced, but according to fig. 3 in error amplifier EA it is defeated
Enter to hold the difference of received signal, variation tendency also has difference, for example, at the first time with the increase of Vc can also increase
Greatly.
Although embodiment is separately illustrated and is illustrated above, it is related to the common technology in part, in ordinary skill
Personnel apparently, can be replaced and integrate between the embodiments, be related to one of embodiment and the content recorded is not known, then
It can refer to another embodiment on the books.Although the present invention is with " the first time information is that a switch periods are interior certainly
Synchronous rectifier shutdown parasitic diode starts time or the shutdown of motor synchronizing rectifying tube that afterflow to secondary current is reduced to zero
Parasitic diode starts afterflow to secondary current and zero time and synchronous rectifier is reduced to open the moment to secondary current reduction
For ratio formed by time to zero ", to illustrate the principle of the present invention, but under continuous conduction mode (CCM), secondary side electricity
Stream will not drop to zero.
Embodiments described above does not constitute the restriction to the technical solution protection domain.It is any in above-mentioned implementation
Modifications, equivalent substitutions and improvements etc., should be included in the protection model of the technical solution made by within the spirit and principle of mode
Within enclosing.
Claims (10)
1. a kind of isolated switching circuit, including master power switch pipe, transformer and synchronous rectifier, the transformer includes original
Side winding and vice-side winding, the master power switch pipe are connect with the primary side winding, the synchronous rectifier with it is described
Vice-side winding connects；It is characterized in that：
Secondary side control circuit receives the first control signal of characterization first time information, the secondary side control circuit with it is described same
The control terminal connection of rectifying tube is walked, the first control signal is used to control the shutdown of synchronous rectifier；When described first
Between information be the time of afterflow of parasitic diode or synchronous rectifier shutdown after synchronous rectifier shutdown in switch periods
The time of afterflow of parasitic diode and synchronous rectifier open ratio formed by the time that the moment terminates to secondary side afterflow afterwards；
The first time information is detected from primary side, the detection signal for characterizing the first time information is obtained, according to the table
The detection signal for levying first time information, is adjusted the state of master power switch pipe through primary-side-control circuit；
When the first control signal is higher than third threshold value, then the isolated switching circuit works in fixed frequency, solid at this
Determine under frequency, the isolated switching circuit enters continuous conduction mode or discontinuous conduction mode.
2. isolated switching circuit according to claim 1, which is characterized in that the first control signal is by with lower section
Formula obtains：The output voltage or/and output current for sampling the isolated switching circuit, obtain sampled voltage signal, will be described
Sampled voltage signal is compared with the first reference signal, obtains the first control signal of characterization first time information.
3. isolated switching circuit according to claim 1 or 2, which is characterized in that believed at the first time according to the characterization
The detection signal of breath adjusts the peak point current of the second time or/and primary side winding, and second time is from current switch week
Phase terminates between the time of next switch periods master power switch pipe turn-on instant or two switch periods start times
Every the time.
4. isolated switching circuit according to claim 1, which is characterized in that described to detect the first time from primary side
Information refers to, by directly detecting or being detected by auxiliary winding the voltage at master power switch pipe both ends, according to master power switch
The variation characteristic of pipe both end voltage obtains the detection signal for characterizing the first time information.
5. isolated switching circuit according to claim 3, which is characterized in that the first time information of current switch period
More than the first time information of a upper switch periods, then so that second time accordingly increase, or/and, reduce primary side around
The peak point current of group；The first time information of current switch period is less than the first time information of a upper switch periods, then makes
Obtaining second time accordingly reduces, or/and, improve the peak point current of primary side winding.
6. isolated switching circuit according to claim 3, which is characterized in that the first time information of current switch period
More than the first time information of a upper switch periods, then so that second time accordingly reduce, or/and, improve primary side around
The peak point current of group；The first time information of current switch period is less than the first time information of a upper switch periods, then makes
Must accordingly it reduce second time, or/and, improve the peak point current of primary side winding.
7. isolated switching circuit according to claim 3, which is characterized in that second time or/and primary side winding
Peak point current increased or reduced with the increase of first time.
8. isolated switching circuit according to claim 4, which is characterized in that when the first time information is more than first
Threshold value or less than second threshold when, then control the master power switch pipe and be held off until being waken up or making isolated again
The switching frequency of switching circuit is maintained detection frequency, and whether the detection frequency changes for periodically judging to load,
If changing, the operating mode of isolated switching circuit is adjusted.
9. isolated switching circuit according to claim 1, which is characterized in that will terminate from current switch period to next
Interval time between the time or two switch periods start times of switch periods master power switch pipe turn-on instant is as
Two times；It is superimposed disturbing signal on second time, so that switching circuit is worked in and trembles frequency pattern, alternatively, in switching frequency
When being preferably minimized, switching circuit is set to work in interval mould to further decrease switching frequency by extending second time
Formula.
10. a kind of control method of isolated switching circuit, the isolated switching circuit include master power switch pipe, transformation
Device and synchronous rectifier, the transformer include primary side winding and vice-side winding, the master power switch pipe and the primary side
Winding connects, and the synchronous rectifier is connect with the vice-side winding, which is characterized in that
The control method includes the following steps：Secondary side control circuit receives the first control letter of characterization first time information
Number, the secondary side control circuit is connect with the control terminal of the synchronous rectifier, and the first control signal is for controlling
The shutdown of synchronous rectifier；The first time information is parasitic diode after synchronous rectifier shutdown in a switch periods
Time of afterflow or synchronous rectifier shutdown after time of afterflow and the synchronous rectifier of parasitic diode open the moment to secondary side
Ratio formed by the time that current stream terminates；
The first time information is detected from primary side, the detection signal for characterizing the first time information is obtained, according to the table
The detection signal for levying first time information, is adjusted the state of master power switch pipe through primary-side-control circuit；
When the first control signal is higher than third threshold value, then the isolated switching circuit works in fixed frequency, solid at this
Determine under frequency, the isolated switching circuit enters continuous conduction mode or discontinuous conduction mode.
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| CN114389454A (en) * | 2020-10-21 | 2022-04-22 | 上海南芯半导体科技股份有限公司 | Secondary side control method and secondary side control system of isolated power supply |
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| CN113224933A (en) * | 2021-05-14 | 2021-08-06 | 杭州欧佩捷科技有限公司 | Secondary side-to-primary side isolation control method of isolation converter |
| CN113224933B (en) * | 2021-05-14 | 2022-08-09 | 杭州欧佩捷科技有限公司 | Secondary side-to-primary side isolation control method of isolation converter |
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| CN113315382A (en) * | 2021-06-04 | 2021-08-27 | 中国电子科技集团公司第五十八研究所 | Non-optical-coupling secondary-side adjusting type isolation switch circuit and control method thereof |
| US11742750B2 (en) | 2021-10-11 | 2023-08-29 | Halo Microelectronics International | Boost converter apparatus and control method |
| WO2023078362A1 (en) * | 2021-11-04 | 2023-05-11 | 力源科技有限公司 | Switching power supply control method and switching power supply |
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| CN113972839A (en) * | 2021-12-27 | 2022-01-25 | 广东希荻微电子股份有限公司 | Control method and controller of boost converter and power conversion device |
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