CN107425728A - The digital optimal control method and its system of a kind of LLC full-bridge converters synchronous rectification - Google Patents
The digital optimal control method and its system of a kind of LLC full-bridge converters synchronous rectification Download PDFInfo
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- CN107425728A CN107425728A CN201710589939.XA CN201710589939A CN107425728A CN 107425728 A CN107425728 A CN 107425728A CN 201710589939 A CN201710589939 A CN 201710589939A CN 107425728 A CN107425728 A CN 107425728A
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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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- 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
- H02M3/33507—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 with automatic control of the output voltage or current, e.g. flyback converters
- H02M3/33515—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 with automatic control of the output voltage or current, e.g. flyback converters with digital control
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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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
- Rectifiers (AREA)
Abstract
The digital optimal control method and its system of a kind of LLC full-bridge converters synchronous rectification, drain terminal voltage before the synchronous rectifier shut-off of full-bridge LLC secondary and after shut-off is sampled respectively, double sampling result is subjected to logic comparison by comparator, the turn-off time of full-bridge LLC secondary synchronous rectifiers is adjusted and utilized with the interruption of microcontroller from microcontroller according to logic comparative result, realize the accurate sampling of LLC secondary synchronous rectifiers shut-off front and back leak terminal voltage, the time adjusted by comparing the needs provided by microcontroller in real time orders, realize that full-bridge LLC secondary synchronous rectifiers turn off in the best time, improve the whole efficiency of full-bridge LLC circuits.
Description
Technical field
The present invention relates to the LLC resonant full bridge switch converters using synchronous rectification mode, more particularly to a kind of LLC full-bridges
The digital optimal control method and its system of transducer synchronous rectification.
Background technology
At present, the switching frequency more and more higher in LLC power converters, switching frequency to increase the advantages of bringing as follows：
1. energy storage device (inductance, transformer, electric capacity etc.) volume in circuit reduces accordingly.2. the power density of whole circuit enters one
Step increase.But the increase of switching frequency also brings the increase of various switching losses and conduction loss, thus synchronous rectification quilt
Widely apply to substitute the rectification of diode, especially in the case where exporting high current.
At present, the synchronous rectification control method applied to LLC topological circuits has 3 classes：Electric current testing；Self-driven simulation electricity
Press detection method；Using microcontroller or FPGA as leading digital detecting technique.Wherein, current detection technology is more accurate, but
The energy loss for being resistance caused by current detecting is suitable big, therefore can influence overall topological efficiency.Detection
Synchronous rectifier drain terminal voltage turns into the efficient synchronous rectification control program of only one, based on detection synchronous rectifier hourglass source electrode
The analog voltage detection technique of voltage has sufficiently complex circuit structure, just can not so meet the requirement of high power density, together
When, such a technology can cause parasitic gate to shake.It is to compare at present using microcontroller or FPGA as leading digital detecting technique
Preferable source-drain voltage detection technique, at present, a kind of more common synchronous rectification control program mainly detect synchronous whole
Whether the body diode of flow tube turns on, rapid adaptive if conducting to close synchronous rectifier, but this scheme mainly by
It the influence that body diode turns on and reverse-conducting switches between the two, can reduce whole LLC circuit efficiencies, while accordingly
The ratio that latency issue can highlight at high frequencies is more serious.
As present generation power supplies are towards high power density, efficient development, excellent simple digital synchronous rectification controlling party
Method is extremely necessary, how so that LLC secondary synchronous rectifiers are particularly important in an optimal shut-off point shut-off.
The content of the invention
The present invention seeks to the deficiency for existing LLC circuits secondary synchronous rectification control method, there is provided a kind of LLC is complete
The digital optimal control method and its system of bridge transducer synchronous rectification, can be such that LLC secondary synchronous rectifiers are most preferably turning off
Point shut-off.
To achieve these goals, the technical scheme taken is as follows by the present invention：A kind of LLC full-bridge converters synchronous rectification
Digital optimal control method, based on detecting the drain terminal voltage of full-bridge LLC secondary synchronous rectifiers, it is adaptively adjusted shut-off
The time of LLC secondary synchronous rectifiers, it is characterised in that：To before the shut-off of the synchronous rectifier of full-bridge LLC secondary and shut-off
Drain terminal voltage afterwards is sampled respectively, and double sampling result is carried out into logic comparison by comparator, compares knot according to logic
Fruit is adjusted to the turn-off time of full-bridge LLC secondary synchronous rectifiers by microcontroller and utilizes the interruption of microcontroller to match somebody with somebody
Close, realize LLC secondary synchronous rectifiers shut-off before and after source and drain terminal voltage accurate sampling, by compare in real time by microcontroller to
The time order that the needs gone out adjust, realizes that full-bridge LLC secondary synchronous rectifiers turn off in the best time, improves full-bridge LLC electricity
The whole efficiency on road.
Comprise the following steps：
1) first in a cycle, before the shut-off of full-bridge LLC secondary synchronous rectifiers, synchronous rectification is detected for the first time
The voltage of pipe drain terminal, while it is stored in microcontroller and exports the reference threshold electricity compared to comparator as logic
Pressure, after the shut-off of full-bridge LLC secondary synchronous rectifiers, second of the voltage for detecting synchronous rectifier drain terminal；
2) the drain voltage i.e. reference threshold voltage and of obtained full-bridge LLC secondary synchronous rectifiers will be detected for the first time
The drain terminal voltage for the full-bridge LLC secondary synchronous rectifiers that secondary detection obtains carries out logic comparison, same with what is detected for the first time
The drain terminal voltage of step rectifying tube subtracts the drain terminal voltage of the synchronous rectifier detected for the second time as logic comparative result, if
Logic comparative result is then designated as logical one, is otherwise designated as logical zero just, to illustrate the conducting of the body diode of synchronous rectifier；
3) microcontroller is transferred to adjust the turn-off time of full-bridge LLC secondary synchronous rectifiers logic comparative result
It is whole.If the logic comparative result of output is " 1 ", microcontroller postpones a period of time shut-off full-bridge LLC in next cycle
Synchronous rectifier, if output logic comparative result be " 0 ", show that now synchronous rectifier turn-off criterion is substantially met；
4) need to carry out next step judgement when logic comparative result is " 0 ", judge that full-bridge LLC secondary now is synchronously whole
Whether the drain terminal voltage of flow tube meets within safe range, that is, ensures the synchronous rectifier leakage of second of detection in a cycle
Terminal voltage is negative, if the synchronous rectifier drain terminal voltage of second detection is regular representation be not within safe range, to prevent
Only there is excessively regulation phenomenon too late in the time of synchronous rectifier shut-off, causes the consequence that electric current pours in down a chimney occur；
5) it is " 0 " in logic comparative result, while meets the leakage of synchronous rectifier detected for the second time within this cycle
Terminal voltage is to be negative i.e. within safe range, then microcontroller keeps output constant to the clock signal of synchronous rectifier, i.e., now
The shut-off moment of synchronous rectifier is more satisfactory；
6) above-mentioned steps are circulated in next cycle so that synchronous rectifier turns off in optimum time point.
Using microcontroller interruption coordinate, realize LLC secondary synchronous rectifiers shut-off before and after source-drain voltage it is accurate
The method of sampling is as follows：
1) in a cycle, internal clocking trailing edge in the logic unit of microcontroller is broken as at the t0 moment
Mouthful；
2) in the trailing edge of t1 instance sample full-bridge LLC secondary synchronous rectifier drain voltages, microcontroller at this moment
Logic unit internal clocking produce interruption；
3) the t3 moment interrupts before the shut-off of full-bridge LLC secondary synchronous rectifiers, while sampling full-bridge LLC pairs for the first time
The drain terminal voltage of synchronous rectifier；
4) the t4 moment interrupts after the shut-off of full-bridge LLC secondary synchronous rectifiers, while second of sampling full-bridge LLC
The drain terminal voltage of secondary synchronous rectifier.
The control system of the digital optimal control method of above-mentioned LLC full-bridge converters synchronous rectification, it is characterised in that：Including
Full-bridge LLC topological circuits, full-bridge LLC topological circuit secondary synchronous rectifiers drain voltage detection circuit, using microcontroller as core
The control circuit and isolated drive circuit of the heart；
Full-bridge LLC topological circuit secondary synchronous rectifiers drain voltage detection circuit includes full-bridge LLC topological circuit secondary
Drain terminal voltage sampling circuit, comparator CMP and the resistance R of synchronous rectifier0With electric capacity C0The filter circuit of composition；Full-bridge LLC
The drain terminal voltage sampling circuit of topological circuit secondary synchronous rectifier includes resistance R1, resistance R2And diode Db, resistance R1's
One end connects power source voltage Vcc, resistance R1Other end connection resistance R2One end and diode DbAnode, diode Db's
The drain terminal of any one devices, electricity in negative electrode connection full-bridge LLC topological circuits two devices of secondary
Hinder R2The other end comparator CMP negative terminal is connected for the drain terminal voltage sample output end of the synchronous rectifier, comparator CMP's
Output end connection resistance R0One end, resistance R0Other end connection electric capacity C0One end and as the output end of filter circuit, electricity
Hold C0The other end ground connection；
Control circuit using microcontroller as core includes digital analog converter DAC, analog-digital converter ADC0, logic control list
Member and two clock modules, analog-digital converter ADC0 input connection full-bridge LLC topological circuits secondary synchronous rectifier leakage
The output end of filter circuit in terminal voltage detecting circuit, analog-digital converter ADC0 output and logic control element are bi-directionally connected,
The output all the way of logic control element exports after a clock module connects full-bridge LLC topological circuits secondary two together respectively
The grid of rectification metal-oxide-semiconductor is walked, another way is exported after another clock module, then is connected respectively by isolated drive circuit output
The grid of full-bridge LLC topological circuits four metal-oxide-semiconductors of primary side is connect, also exports after digital analog converter DAC feedback link all the way extremely
Comparator CMP anode in LLC topological circuit secondary synchronous rectifier drain voltage detection circuits；
When whole system start start when, LLC topological circuits start working, while the primary side metal-oxide-semiconductor of LLC topological circuits with
Secondary synchronous rectifier cooperating, secondary synchronous rectifier turn off according to switching frequency is corresponding to the relation progress of resonant frequency
The adjustment of time, LLC circuit secondary synchronous rectifiers drain terminal detects the drain terminal voltage of electric circuit inspection synchronous rectifier, in LLC pairs
Detection detection synchronous rectifier drain terminal voltage, while the synchronous rectifier that will be detected for the first time for the first time before the rectifying tube shut-off of side
Drain terminal voltage comparator CMP anode is connected to as the reference threshold voltage of comparator, in LLC circuit secondary synchronous rectifications
Second detection synchronous rectifier drain terminal voltage after pipe shut-off, and using the synchronous rectifier drain terminal voltage of second of detection as than
Negative terminal input signal compared with device CMP, the drain voltage detected twice are compared, when the pole of body two of LLC secondary synchronous rectifiers
When pipe turns on, comparator CMP logic output is " 1 ", now controls LLC secondary by microcontroller for the control system of core
Synchronous rectifier extends certain ON time in next cycle, while constantly judges that in the ensuing cycle what it compared patrols
It is " 0 " that output, which is collected, up to logic exports, and when comparator logic output is " 0 ", while judges its week in logic output for " 0 "
In phase the drain terminal voltage of second of sampling ensures that the synchronization of second of detection in a cycle is whole whether within safe range
Flow tube drain terminal voltage is negative, if the synchronous rectification tube voltage of second detection is regular representation be not within safe range, with
The problem of overregulating is prevented, when the drain terminal voltage of second sampling meets in safe range, that is, the synchronous rectifier detected
Drain terminal voltage for after negative, then the turn-off time of LLC secondary synchronous rectifiers now be defaulted as the time most preferably turned off, now
The efficiency of whole LLC topological circuits has reached highest efficiency.
Advantages of the present invention and remarkable result：
1st, using digital control, it is more flexible compared to the application of traditional simulation control digital control algorithm, control
Precision is more increased.
2nd, in same period, using the drain voltage of the LLC circuit secondary synchronous rectifiers of first time sampling as this week
The comparator reference threshold value of phase, so just obtain in an exact references threshold value rather than universal method with periodic time self-adapting
A fixed threshold, thus its adaptive ability is stronger, and the time control of synchronous rectifier shut-off is more accurate.
3rd, in same period, the logic ratio of the drain voltage and the drain voltage of second of sampling of first time sampling is utilized
Adjust the criterion very simplicity and clarity of turn-off time for the control system of core as microcontroller compared with value " 1 " or " 0 ", have
Beneficial to the more accurate turn-off time adjustment of realization.
4th, in the mediation process of control system, while judge whether second of sampling is negative value i.e. safety in same period
In the range of, be advantageous to prevent from overregulating, be achieved in accurately turning off synchronous rectifier, improve efficiency.
Brief description of the drawings
Fig. 1 is control system block diagram of the present invention；
Fig. 2 is present system schematic diagram；
Fig. 3 is control program flow chart of the present invention；
Fig. 4 is LLC circuit secondary synchronous rectifier source-drain voltage detection waveform figures；
Fig. 5 is efficiency comparative curve map of the present invention under full load conditions with universal control method.
Embodiment
The technical scheme of invention is described in detail below in conjunction with the accompanying drawings.
Such as Fig. 1,2, control system of the present invention includes full-bridge LLC topological circuits, full-bridge LLC topological circuit secondary synchronous rectifications
Tube drain voltage detection circuit, control circuit and isolated drive circuit using microcontroller as core.Wherein, full-bridge LLC topologys
Circuit secondary synchronous rectifier drain voltage detection circuit includes the drain terminal voltage of full-bridge LLC topological circuit secondary synchronous rectifiers
Sample circuit, comparator CMP and resistance R0With electric capacity C0The filter circuit of composition.Full-bridge LLC topological circuit secondary synchronous rectifications
The drain terminal voltage sampling circuit of pipe includes resistance R1, resistance R2And diode Db, resistance R1One end connection power source voltage Vcc,
Resistance R1Other end connection resistance R2One end and diode DbAnode, diode DbNegative electrode connection full-bridge LLC topology electricity
Devices M6 drain terminal is (due to the drain terminal of any one in sampling two devices M6 or M5 in the secondary of road
Voltage can, accompanying drawing embodiment is by taking the drain terminal voltage for sampling M6 as an example, similarly hereinafter) resistance R1 and R2 carry out partial pressure sampling, resistance
R2The other end comparator CMP negative terminal is connected for devices M6 drain terminal voltage samples output end, comparator CMP's
Output end connection resistance R0One end, resistance R0Other end connection electric capacity C0One end and as the output end of filter circuit, electricity
Hold C0The other end ground connection.
Control circuit using microcontroller as core includes digital analog converter DAC, analog-digital converter ADC0, logic control list
Member and clock module 1 and clock module 2, analog-digital converter ADC0 input connection full-bridge LLC topological circuits secondary are synchronous
The output end of filter circuit in rectification tube drain voltage detection circuit, analog-digital converter ADC0 output and logic control element are double
To connection, the output all the way of logic control element exports after clock module 1 drives full-bridge LLC topological circuits secondary two respectively
Individual devices M5, M6 grid, another way are exported after clock module 2, then by isolated drive circuit output point
Not Qu Dong four metal-oxide-semiconductor M1- of full-bridge LLC topological circuits primary side M4 grids, also export all the way after digital analog converter DAC anti-
Feedback is connected to the anode of comparator CMP in LLC topological circuit secondary synchronous rectifier drain voltage detection circuits, to store simultaneously
The result that output synchronous rectifier M6 drain voltages sample for the first time in a cycle.
In present system, full-bridge LLC topological circuit secondary synchronous rectifier source and drain terminal voltage sample circuits are in full-bridge LLC
Front and rear the sampling simultaneously of secondary synchronous rectifier shut-off, the voltage subtracted by using the voltage sample value before shut-off after shut-off are adopted
Sample value draws a logic judgment numeral, and the control system that logic judgment numeral is conveyed to using microcontroller as core is realized
The turn-off time adjustment of real-time full-bridge LLC secondary synchronous rectifiers, microcontroller are the control system output signal control of core
Full-bridge LLC secondary synchronous rectifier M5 and M6 processed turns off in the best time.
The course of work of control system：When whole system starts to start, LLC topological circuits are started working, while LLC is opened up
The primary side metal-oxide-semiconductor and secondary synchronous rectifier cooperating of circuit are flutterred, secondary synchronous rectifier is according to switching frequency and resonance frequency
The relation of rate carries out the adjustment of corresponding turn-off time, the drain electrode detection electric circuit inspection synchronous rectification of LLC circuits secondary synchronous rectifier
The drain voltage of pipe, the detection detection synchronous rectifier drain voltage, while by first for the first time before LLC secondary rectifying tube turns off
The drain voltage of the secondary synchronous rectifier detected is connected to comparator CMP anode as the reference threshold voltage of comparator,
Second of detection synchronous rectifier drain voltage after the shut-off of LLC circuits secondary synchronous rectifier, and it is same by what is detected for the second time
Negative terminal input signal of the rectifying tube drain voltage as comparator CMP is walked, the drain voltage detected twice is compared, and works as LLC
During the body diode conducting of secondary synchronous rectifier, comparator CMP logic output is " 1 ", is now core by microcontroller
The control system control LLC secondary synchronous rectifiers of the heart extend certain ON time in next cycle, while following
Cycle constantly judge logic output that it compares until logic is exported as " 0 ", when it is " 0 " that comparator logic, which exports, simultaneously
Judge its logic output for second drain voltage sampled in the cycle of " 0 " whether within safe range to prevent
The problem of overregulating, after the drain voltage of second of sampling meets in safe range, then LLC secondary synchronous rectifications now
The turn-off time of pipe is defaulted as the time most preferably turned off, and the efficiency of whole LLC topological circuits now has reached highest efficiency.
Such as Fig. 3, the control method of control system of the present invention is before being turned off to the synchronous rectifier of full-bridge LLC secondary and closed
Drain terminal voltage after disconnected is sampled respectively, double sampling result is carried out into logic comparison by comparator, according to logic ratio
The turn-off time of full-bridge LLC secondary synchronous rectifiers is adjusted by microcontroller compared with result and utilizes the interruption of microcontroller
Coordinate, the accurate sampling of source-drain voltage before and after the shut-off of LLC secondary synchronous rectifiers is realized, by comparing in real time by microcontroller
The time order that the needs provided adjust, realizes that full-bridge LLC secondary synchronous rectifiers turn off in the best time, improves full-bridge LLC
The whole efficiency of circuit.Comprise the following steps：
1) first in a cycle, detection for the first time is synchronous whole before full-bridge LLC secondary synchronous rectifiers M6 shut-offs
The voltage VSR (1) of flow tube M6 drain electrodes, while be stored to using microcontroller in the control system of core and to export to comparing
Device CMP anode, the voltage of second of detection synchronous rectifier M6 drain electrode after full-bridge LLC secondary synchronous rectifiers M6 shut-offs
VSR (2) is simultaneously stored.
2) the voltage VSR (1) that the full-bridge LLC secondary synchronous rectifiers M6 of first time detection drains with detecting for the second time
Synchronous rectifier M6 voltage VSR (2) is compared, and is subtracted with the synchronous rectifier M6 of first time detection drain voltage VSR (1)
The synchronous rectifier drain voltage VSR (2) detected for the second time is gone to be transported to as comparator CMP output result with microcontroller
Device is the digital logic unit of the control system of core, wherein output comparative result is just, that is, synchronous rectifier M6 body
Diode current flow, then logical one is designated as, is otherwise designated as logical zero.
3) when according to shut-off of the Digital Logic result of CMP outputs to full-bridge LLC secondary synchronous rectifiers M5 and M6 is compared
Between be adjusted.Wherein, it is the control system of core under using microcontroller if the logic comparative result of output is " 1 "
A cycle delay a period of time shut-off full-bridge LLC synchronous rectifier M6, if the logic comparative result of output is " 0 ",
Show that now synchronous rectifier M6 turn-off criterions are substantially met.
4) need to carry out next step judgement when logic output result is " 0 ", judge that full-bridge LLC secondary now is synchronously whole
Whether flow tube M6 drain voltages meet in certain safe range (to ensure the synchronous rectification of second of detection in a cycle
Pipe M6 drain terminal voltages VSR (2) storage value is negative, if synchronous rectifier M6 drain terminal voltages VSR (2) storage value of second of detection is
Regular representation is within safe range) to prevent the time of M6 shut-offs too late, it result in and the phenomenon that electric current pours in down a chimney occur.
5) meeting that the output of comparator CMP logics is " 0 ", while the synchronization that satisfaction detects for the second time within this cycle is whole
Flow tube M6 drain voltages (M6 drain terminal voltage VSR (2) are negative) within safe range, then keep this synchronous rectifier M6 arteries and veins
The wide cycle is constant.
6) above-mentioned steps are circulated in next cycle so that synchronous rectifier turns off in optimum time point.
To realize the accurate sampling of source-drain voltage before and after the shut-off of LLC secondary synchronous rectifiers, microcontroller is core
The time of control system interrupts flow and comprised the following steps：
1) in a cycle, the t0 moment using controller for core control system internal clocking trailing edge as in
Break mouth.
2) in the trailing edge of t1 instance sample full-bridge LLC secondary synchronous rectifier M6 drain voltages, at this moment with micro-control
Device processed produces interruption for the control system internal clocking of core.
3) the t3 moment interrupts before full-bridge LLC secondary synchronous rectifiers M6 shut-offs, while sampling full-bridge LLC for the first time
Secondary synchronous rectifier M6 drain voltages.
4) the t4 moment interrupts after full-bridge LLC secondary synchronous rectifiers M6 shut-offs, while second of this sampling is complete
Bridge LLC secondary synchronous rectifier M6 drain voltages.
As shown in figure 4, be LLC circuit secondary synchronous rectifier drain terminal voltage detecting oscillograms, its waveform detected be
Switching frequency is less than the waveform in the case of resonant frequency, it can be seen that the detection synchronous rectifier shut-off in Fig. 4 (a)
Front and rear drain terminal voltage simultaneously carries out logic judgment, if at this moment there is VSR (1)>VSR (2), and now two voltages are respectively less than zero,
Then now logic judgment is " 1 ", then M6 is delayed to turn off a period of time.As shown in Fig. 4 (b), if next week after adjustment
Still there is VSR (1) phase>VSR (2), and there are still two voltages to be less than zero, then and now logic judgment is still " 1 ", then M6 is still
It is old to continue to be delayed to turn off a period of time.If VSR (1)<VSR (2), now devices M6 may be just in its electric current
Zero crossing turns off, then needs further to be judged, if VSR (1) is also negative for negative and VSR (2), as shown in Fig. 4 (d), then
Next switch periods synchronous rectifier M6 turn-off time keeps constant.If VSR (2) for just, as shown in Fig. 4 (c), then micro-control
Device processed can control next switch periods devices M6 drive signals, by next switch periods devices M6
Turn-off time shift to an earlier date a period of time.
Fig. 5 is the corresponding efficiency curve diagram under full load conditions, and wherein the curve map of origin is bent for the efficiency of universal method
Line chart, its peak efficiency reaches 97.5%, and corresponding triangle curve figure is efficiency curve diagram corresponding to the present invention, compared to
Its efficiency on the whole of the efficiency curve diagram of universal method is higher by 0.5% or so.
Claims (4)
- A kind of 1. digital optimal control method of LLC full-bridge converters synchronous rectification, to detect full-bridge LLC secondary synchronous rectifiers Drain terminal voltage based on, be adaptively adjusted shut-off LLC secondary synchronous rectifiers time, it is characterised in that：To full-bridge LLC Drain terminal voltage before the synchronous rectifier shut-off of secondary and after shut-off is sampled respectively, and double sampling result is passed through into ratio Logic comparison, the turn-off time according to logic comparative result by microcontroller to full-bridge LLC secondary synchronous rectifiers are carried out compared with device It is adjusted and utilizes the interruption of microcontroller to coordinate, realizes the essence of source and drain terminal voltage before and after the shut-off of LLC secondary synchronous rectifiers Really sampling, the time adjusted by comparing the needs provided by microcontroller in real time order, and realize full-bridge LLC secondary synchronous rectifications Pipe turns off in the best time, improves the whole efficiency of full-bridge LLC circuits.
- 2. the digital optimal control method of LLC full-bridge converters synchronous rectification according to claim 1, it is characterised in that Comprise the following steps：1) first in a cycle, before the shut-off of full-bridge LLC secondary synchronous rectifiers, synchronous rectifier leakage is detected for the first time The voltage at end, while be stored in microcontroller and export the reference threshold voltage compared to comparator as logic, After the shut-off of full-bridge LLC secondary synchronous rectifiers, second of the voltage for detecting synchronous rectifier drain terminal；2) the drain voltage i.e. reference threshold voltage of obtained full-bridge LLC secondary synchronous rectifiers and second will be detected for the first time The drain terminal voltage for detecting obtained full-bridge LLC secondary synchronous rectifiers carries out logic comparison, whole with the synchronization detected for the first time The drain terminal voltage of flow tube subtracts the drain terminal voltage of the synchronous rectifier detected for the second time as logic comparative result, if logic Comparative result is then designated as logical one, is otherwise designated as logical zero just, to illustrate the conducting of the body diode of synchronous rectifier；3) microcontroller is transferred to be adjusted the turn-off time of full-bridge LLC secondary synchronous rectifiers logic comparative result.Such as The logic comparative result of fruit output is " 1 ", then microcontroller postpones a period of time shut-off full-bridge LLC synchronization in next cycle Rectifying tube, if the logic comparative result of output is " 0 ", show that now synchronous rectifier turn-off criterion is substantially met；4) need to carry out next step judgement when logic comparative result is " 0 ", judge full-bridge LLC secondary synchronous rectifiers now Drain terminal voltage whether meet within safe range, that is, ensure the synchronous rectifier drain terminal electricity of second detection in a cycle It is negative to press, if it is not within safe range, to prevent synchronization whole that the synchronous rectification tube voltage of second of detection, which is regular representation, There is excessively regulation phenomenon too late in the time of flow tube shut-off, causes the consequence that electric current pours in down a chimney occur；5) it is " 0 " in logic comparative result, while meets the drain terminal electricity of synchronous rectifier detected for the second time within this cycle Press to be negative i.e. within safe range, then microcontroller keeps output constant to the clock signal of synchronous rectifier, i.e., now synchronous The shut-off moment of rectifying tube is more satisfactory；6) above-mentioned steps are circulated in next cycle so that synchronous rectifier turns off in optimum time point.
- 3. the digital optimal control method of LLC full-bridge converters synchronous rectification according to claim 1 or 2, its feature exist In：Coordinated using the interruption of microcontroller, realize the accurate sampling of source-drain voltage before and after the shut-off of LLC secondary synchronous rectifiers Method is as follows：1) in a cycle, at the t0 moment using internal clocking trailing edge in the logic unit of microcontroller as interruption entrance；2) in the trailing edge of t1 instance sample full-bridge LLC secondary synchronous rectifier drain voltages, microcontroller is patrolled at this moment Collect unit internal clocking and produce interruption；3) the t3 moment interrupts before the shut-off of full-bridge LLC secondary synchronous rectifiers, while sampling full-bridge LLC secondary is same for the first time Walk the drain terminal voltage of rectifying tube；4) the t4 moment interrupts after the shut-off of full-bridge LLC secondary synchronous rectifiers, while second of sampling full-bridge LLC secondary The drain terminal voltage of synchronous rectifier.
- 4. the control system of the digital optimal control method of LLC full-bridge converters synchronous rectification according to claim 1, it is special Sign is：Including full-bridge LLC topological circuits, full-bridge LLC topological circuit secondary synchronous rectifiers drain voltage detection circuit, with micro- Controller is the control circuit and isolated drive circuit of core；It is synchronous that full-bridge LLC topological circuit secondary synchronous rectifiers drain voltage detection circuit includes full-bridge LLC topological circuits secondary Drain terminal voltage sampling circuit, comparator CMP and the resistance R of rectifying tube0With electric capacity C0The filter circuit of composition；Full-bridge LLC topologys The drain terminal voltage sampling circuit of circuit secondary synchronous rectifier includes resistance R1, resistance R2And diode Db, resistance R1One end Connect power source voltage Vcc, resistance R1Other end connection resistance R2One end and diode DbAnode, diode DbNegative electrode Connect the drain terminal of any one devices in full-bridge LLC topological circuits two devices of secondary, resistance R2 The other end comparator CMP negative terminal, comparator CMP output are connected for the drain terminal voltage sample output end of the synchronous rectifier End connection resistance R0One end, resistance R0Other end connection electric capacity C0One end and as the output end of filter circuit, electric capacity C0 The other end ground connection；Using microcontroller as core control circuit include digital analog converter DAC, analog-digital converter ADC0, logic control element with And two clock modules, analog-digital converter ADC0 input connection full-bridge LLC topological circuit secondary synchronous rectifiers drain terminal electricity The output end of filter circuit, analog-digital converter ADC0 output and logic control element are bi-directionally connected in pressure detection circuit, logic It is whole that the output all the way of control unit exports connection full-bridge LLC topological circuits two synchronizations of secondary respectively after a clock module The grid of metal-oxide-semiconductor is flowed, another way is exported after another clock module, then connection is complete respectively by isolated drive circuit output The grid of bridge LLC topological circuits four metal-oxide-semiconductors of primary side, feedback link is also exported after digital analog converter DAC all the way and is opened up to LLC Flutter the anode of comparator CMP in circuit secondary synchronous rectifier drain voltage detection circuit；When whole system starts to start, LLC topological circuits are started working, while the primary side metal-oxide-semiconductor and secondary of LLC topological circuits Synchronous rectifier cooperating, relation progress corresponding turn-off time of the secondary synchronous rectifier according to switching frequency to resonant frequency Adjustment, LLC circuit secondary synchronous rectifiers drain terminal detect electric circuit inspection synchronous rectifier drain terminal voltage, it is whole in LLC secondary Detection detection synchronous rectifier drain terminal voltage, while by the leakage of the synchronous rectifier detected for the first time for the first time before flow tube shut-off Terminal voltage is connected to comparator CMP anode as the reference threshold voltage of comparator, is closed in LLC circuits secondary synchronous rectifier Have no progeny second of detection synchronous rectifier drain terminal voltage, and using the synchronous rectifier drain terminal voltage of second of detection as comparator CMP negative terminal input signal, the drain voltage detected twice are compared, when the body diode of LLC secondary synchronous rectifiers is led When logical, comparator CMP logic output is " 1 ", now controls LLC secondary synchronous for the control system of core by microcontroller Rectifying tube extends certain ON time in next cycle, while constantly judges that the logic that it compares is defeated in the ensuing cycle It is " 0 " to go out up to logic exports, and when comparator logic output is " 0 ", while judges that it is exported as in the cycle of " 0 " in logic The drain terminal voltage of second of sampling ensures the synchronous rectifier of second of detection in a cycle whether within safe range Drain terminal voltage is negative, if it is not within safe range, to prevent that the synchronous rectification tube voltage of second of detection, which is regular representation, The problem of overregulating, when the drain terminal voltage of second sampling meets in safe range, that is, the synchronous rectifier drain terminal detected Voltage for after negative, then the turn-off time of LLC secondary synchronous rectifiers now be defaulted as the time most preferably turned off, now entirely The efficiency of LLC topological circuits has reached highest efficiency.
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