CN110445403A - A kind of SR avoiding improper opening control method - Google Patents
A kind of SR avoiding improper opening control method Download PDFInfo
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- CN110445403A CN110445403A CN201910739236.XA CN201910739236A CN110445403A CN 110445403 A CN110445403 A CN 110445403A CN 201910739236 A CN201910739236 A CN 201910739236A CN 110445403 A CN110445403 A CN 110445403A
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- oxide
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- vds
- comparator
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M7/2176—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only comprising a passive stage to generate a rectified sinusoidal voltage and a controlled switching element in series between such stage and the output
Abstract
The invention discloses a kind of SR avoiding improper opening control methods, using the circuit being made of transformer, metal-oxide-semiconductor and SR chip, the control of metal-oxide-semiconductor grid is realized by slope detection, if rate of rise value is greater than threshold slope, then allow to open the grid of metal-oxide-semiconductor, grid that is on the contrary then forbidding opening metal-oxide-semiconductor when reaching cut-in voltage；If can not detect that slope or slope are less than to require, two threshold voltages are then set in the curve graph of Vds, judge the rise time and fall time between two threshold voltages, if the difference of the two is greater than the threshold time of setting, then allow to open the grid of metal-oxide-semiconductor, it is on the contrary then forbid opening；Solve existing control method secondary side freewheel current it is smaller when, be not easy to distinguish Vds normal failing edge and concussion two kinds in the case of slope, thus be not easy to control SR Gate switch the problem of, can accurately control the state of metal-oxide-semiconductor grid.
Description
Technical field
The present invention relates to synchronous rectification fields, specifically, being to be related to a kind of SR avoiding improper opening control method.
Background technique
In traditional AC-DC system, as shown in Figure 1, being a diode on secondary side, since efficiency requires increasingly
Height, the forward voltage drop of diode are typically all 0.7V or more, this power consumption is especially big, more next at present to realize high energy efficiency
More tend to using SR technology, i.e., replace original diode with SR (synchronous rectification) chip and metal-oxide-semiconductor, passes through Vds voltage control
The switch of SR Gate processed, Vds are the VD pin of chip and the voltage difference of VSS pin.In such circuit, when secondary side afterflow,
When Vds becomes negative voltage, after the grid of metal-oxide-semiconductor should be at opening state, but secondary current is zero, there is shake in the Vds on secondary side
It swings, when earthquake is to negative value, the grid of metal-oxide-semiconductor should not be opened at this time, therefore, distinguish secondary side afterflow and concussion is control MOS
The key of tube grid state.
Existing differentiating method is the slope for detecting Vds failing edge, but when underloading (or secondary side freewheel current is small), Vds
Normal failing edge and concussion slope difference it is little, cannot be distinguished.
Summary of the invention
The purpose of the present invention is to provide a kind of SR avoiding improper opening control methods, solve the secondary side afterflow electricity of existing control method
It when flowing smaller, is not easy to distinguish the slope in the case of two kinds of the normal failing edge of Vds and concussion, to be not easy to control SR
The problem of switch of Gate.
To achieve the above object, The technical solution adopted by the invention is as follows:
A kind of SR avoiding improper opening control method using the circuit being made of transformer, metal-oxide-semiconductor and SR chip, including walks as follows
It is rapid:
(a1) after voltage is connected on the main side of transformer, metal-oxide-semiconductor drain electrode and the source voltage difference Vds on secondary side rise, inspection
Survey the rate of rise of Vds；
(a2) if the rate of rise of Vds is greater than the threshold slope of setting, allow to open by the control terminal VG of SR chip
The grid of metal-oxide-semiconductor.
Specifically, the detection circuit of the Vds rate of rise includes comparator OP1 and the end comparator OP2, CF in step (a1)
It is connected to the d type flip flop D1 of comparator OP1 output end, grid is connected to the metal-oxide-semiconductor Q2 of comparator OP2 output end, and grid passes through
NOT gate is connected to the metal-oxide-semiconductor Q1 of comparator OP2 output end, and one end connects with the source electrode of the drain electrode of metal-oxide-semiconductor Q1 and metal-oxide-semiconductor Q2 respectively
Connect, the capacitor C1 of the source electrode of the other end and metal-oxide-semiconductor Q1 connection and inverting input terminal be connected to metal-oxide-semiconductor Q2 drain electrode comparison
Device OP3, the drain electrode of the metal-oxide-semiconductor Q2 are connected with current source I1, the normal phase input end of the comparator OP3 and the source of metal-oxide-semiconductor Q1
Voltage source U1 is connected between pole, the output end of the comparator OP3 is connect with the end D of d type flip flop D1, the comparator OP1,
The normal phase input end of OP2 is connect with Vds, and the inverting input terminal of the comparator OP1 loads threshold voltage vt h1, the comparison
The inverting input terminal of device OP2 loads threshold voltage vt h2.
A kind of SR avoiding improper opening control method using the circuit being made of transformer, metal-oxide-semiconductor and SR chip, including walks as follows
It is rapid:
(b1) after transformer primary connects voltage, if the amplitude that the Vds on secondary side rises is smaller, it can't detect Vds
The rate of rise；
(b2) threshold voltage vt h3 and Vth4 are set, the rise time T1 and fall time T2 of Vds in this section are detected, if
T1-T2 > Tth then allows to open the grid of metal-oxide-semiconductor by the control terminal VG of SR chip, and there is no concussions by secondary side Vds at this time；
Otherwise, forbid opening the grid of metal-oxide-semiconductor；
Wherein, Tth is threshold time.
Specifically, in step (b2), the circuit of detection Vds rise time and fall time include concatenated switch K1 with
K2, one end is connected on the tie point of switch K1 and K2, the capacitor C2 of other end ground connection, normal phase input end be connected to switch K1 with
On the tie point of K2, the end comparator OP4, D that inverting input terminal is grounded by voltage source U2 be connected to comparator OP4 output end
D type flip flop D2, the other end of the switch K1 are connected with current source I2, and the other end of the switch K2 is connect by current source I3
Ground.
Specifically, being parallel with the switch K3 for resetting the voltage on capacitor C2 on the capacitor C2.
Compared with prior art, the invention has the following advantages:
The present invention realizes the control of metal-oxide-semiconductor grid by slope detection, if slope value is greater than threshold slope, allows to open
The grid of metal-oxide-semiconductor, it is on the contrary then forbid opening；If slope can not be detected, two threshold value electricity are set in the curve graph of Vds
Pressure, judges the rise time and fall time between two threshold voltages, if the difference of the two is greater than the threshold time of setting,
Allow to open the grid of metal-oxide-semiconductor, it is on the contrary then forbid opening；Solve existing control method secondary side freewheel current it is smaller when, no
The normal failing edge and the slope in the case of two kinds of concussion of easily distinguishable Vds, to be not easy to asking for the switch of control SR Gate
Topic, can accurately control the state of metal-oxide-semiconductor grid.
Detailed description of the invention
Fig. 1 is the circuit diagram of existing ACDC system.
Fig. 2 is the waveform diagram of each test point parameter in Fig. 1.
The waveform diagram of threshold value setting and formation when Fig. 3 is detected slope.
Fig. 4 is the waveform diagram of the threshold value setting and formation when slope is not detected.
Fig. 5 is implementation flow chart of the invention.
Fig. 6 is the circuit diagram of Vds rate of rise detection circuit in the present invention.
Fig. 7 is the circuit diagram of Vds rise time and fall time detection circuit in the present invention.
Specific embodiment
The invention will be further described with embodiment for explanation with reference to the accompanying drawing, and mode of the invention includes but not only limits
In following embodiment.
Embodiment
A kind of SR avoiding improper opening control method disclosed by the invention, using the electricity being made of transformer, metal-oxide-semiconductor and SR chip
Road, circuit structure is as shown in Figure 1, the main side of transformer connects input voltage, the output end of the same name ground connection on secondary side, different name output
It holds, the end VSS of SR chip is connect with the source electrode of metal-oxide-semiconductor, the end VG of SR chip and the grid connection of metal-oxide-semiconductor, the VD of SR chip
End is connect with the drain electrode of metal-oxide-semiconductor, and the vdd terminal of the SR chip is connected by the source electrode of capacitor and metal-oxide-semiconductor, the leakage of the metal-oxide-semiconductor
Extremely voltage output end VOUT.
Theoretically, there are the grids that metal-oxide-semiconductor should be opened when afterflow on secondary side, and after secondary side afterflow is zero, oscillation is to negative
The grid of metal-oxide-semiconductor should be closed when voltage, the waveform diagram of formation is as shown in Fig. 2, existing method is distinguished by detection Vds slope
Two kinds of situations of afterflow and concussion, but when freewheel current is smaller, the failing edge slope of Vds and slope difference when concussion are little,
It is not easy to the state of control metal-oxide-semiconductor grid.
Therefore, the present invention provides a kind of SR avoiding improper opening control method, specific control method is as follows:
After voltage is connected on the main side of transformer, metal-oxide-semiconductor drain electrode and the source voltage difference Vds on secondary side rise, secondary at this time
The slope when rate of rise of side Vds is much larger than concussion, detects the rate of rise of Vds, if the rate of rise of Vds is greater than setting
Threshold slope, then allow to open the grid of metal-oxide-semiconductor by the control terminal VG of SR chip, and threshold slope is programmed by Rset and determined.
There are many modes of detected slope, in following Fig. 3, be arranged threshold value Vth1 and Vth2, judge Vth1 and Vth2 when
Between, to obtain slope value.The detection circuit of the Vds rate of rise is present embodiments provided, as shown in fig. 6, the detection circuit packet
It includes comparator OP1 and the end comparator OP2, CF is connected to the d type flip flop D1 of comparator OP1 output end, grid is connected to comparator
The metal-oxide-semiconductor Q2 of OP2 output end, grid are connected to the metal-oxide-semiconductor Q1 of comparator OP2 output end by NOT gate, one end respectively with metal-oxide-semiconductor
The capacitor C1 and inverting input terminal of source electrode connection, the source electrode connection of the other end and metal-oxide-semiconductor Q1 of the drain electrode and metal-oxide-semiconductor Q2 of Q1
It is connected to the comparator OP3 of the drain electrode of metal-oxide-semiconductor Q2, the drain electrode of the metal-oxide-semiconductor Q2 is connected with current source I1, the comparator OP3
Normal phase input end and metal-oxide-semiconductor Q1 source electrode between be connected with voltage source U1, the output end and d type flip flop of the comparator OP3
The end D of D1 connects, and the normal phase input end of described comparator OP1, OP2 are connect with Vds, the anti-phase input of the comparator OP1
The inverting input terminal of end load threshold voltage vt h1, the comparator OP2 load threshold voltage vt h2.
Current source I1, voltage source U1 value by Rset program determine, when Vds voltage be higher than Vth2 when, comparator OP2 is defeated
High level charges to capacitor C1 out, and the voltage of capacitor C1 and the size of time, electric current are proportional；When Vds voltage is higher than Vth1,
The slope of Vds is determined according to the voltage on capacitor C1.
In addition, can't detect main side in some cases opens slope, then controlled with the following method:
When transformer primary different moments connecting voltage, the amplitude or slope that the Vds on secondary side rises may be smaller, then examine
The rate of rise for not detecting Vds meets sets requirement；As shown in figure 4, curve first is that concussion when Vds change curve, curve
Second is that the Vds change curve after voltage is connected on main side, threshold voltage vt h3 and Vth4 are set, detect the upper of Vds in this section
Time T1 and fall time T2 is risen, if T1-T2 > Tth, allows to open the grid of metal-oxide-semiconductor by the control terminal VG of SR chip, this
When secondary side Vds there is no concussion；Otherwise, forbid opening the grid of metal-oxide-semiconductor；Wherein, Tth is threshold time.
The circuit of detection Vds rise time and fall time is present embodiments provided as shown in fig. 7, the circuit includes series connection
Switch K1 and K2, one end is connected on the tie point of switch K1 and K2, the capacitor C2 of other end ground connection, normal phase input end connection
On the tie point of switch K1 and K2, the end comparator OP4, D that inverting input terminal is grounded by voltage source U2 be connected to comparator
The d type flip flop D2 of OP4 output end, the other end of the switch K1 are connected with current source I2, and the other end of the switch K2 passes through
Current source I3 is grounded, and the switch K3 for resetting the voltage on capacitor C2 is parallel on the capacitor C2.
The value of voltage source U2 is programmed by Rset and is determined, switch K1 indicates the rise time, and switch K2 indicates fall time, and
Connecting one at the end CF of d type flip flop D2 indicates the signal that terminates of failing edge, when Vds be in rising edge, i.e., in Vth1 with
It when between Vth2, can charge to capacitor C2, when Vds is in failing edge, that is, when being between Vth3 and Vth4, capacitor C2 be put
Electricity, if the output end of comparator OP4 is high level, then it represents that: T1-Tth > T2 allows to open the grid of metal-oxide-semiconductor, on the contrary then prohibit
The grid for only opening metal-oxide-semiconductor, at the end of failing edge, by the output of d type flip flop D2 latched comparator OP4 as a result, each
Before comparing T1 and T2, the voltage on capacitor C2 is reset by switch K3.
Realization process of the invention by slope detection as shown in figure 5, realize the control of metal-oxide-semiconductor grid, if slope first
Value is greater than threshold slope, then allows to open the grid of metal-oxide-semiconductor, on the contrary then forbid opening；If slope can not be detected, in Vds
Curve graph on two threshold voltages are set, the rise time and fall time between two threshold voltages are judged, if the two
Difference is greater than the threshold time of setting, then allows to open the grid of metal-oxide-semiconductor, on the contrary then forbid opening；So as to accurately control
The state of metal-oxide-semiconductor grid processed.
Above-described embodiment is only one of the preferred embodiment of the present invention, should not be taken to limit protection model of the invention
It encloses, as long as that in body design thought of the invention and mentally makes has no the change of essential meaning or polishing, is solved
The technical issues of it is still consistent with the present invention, should all be included within protection scope of the present invention.
Claims (5)
1. a kind of SR avoiding improper opening control method, using the circuit being made of transformer, metal-oxide-semiconductor and SR chip, which is characterized in that packet
Include following steps:
(a1) after voltage is connected on the main side of transformer, metal-oxide-semiconductor drain electrode and the source voltage difference Vds on secondary side rise, and detect Vds
The rate of rise；
(a2) if the rate of rise of Vds is greater than the threshold slope of setting, allow to open metal-oxide-semiconductor by the control terminal VG of SR chip
Grid.
2. a kind of SR avoiding improper opening control method, using the circuit being made of transformer, metal-oxide-semiconductor and SR chip, which is characterized in that packet
Include following steps:
(b1) after transformer primary connects voltage, if the amplitude that the Vds on secondary side rises is smaller, it can't detect the upper of Vds
Rise slope；
(b2) threshold voltage vt h3 and Vth4 are set, the rise time T1 and fall time T2 of Vds in this section are detected, if T1-
T2 > Tth then allows to open the grid of metal-oxide-semiconductor by the control terminal VG of SR chip, and there is no concussions by secondary side Vds at this time；It is no
Then, forbid opening the grid of metal-oxide-semiconductor；
Wherein, Tth is threshold time.
3. a kind of SR avoiding improper opening control method according to claim 1, which is characterized in that in step (a1), Vds rises oblique
The detection circuit of rate includes the d type flip flop D1 that comparator OP1 and the end comparator OP2, CF are connected to comparator OP1 output end, grid
Pole is connected to the metal-oxide-semiconductor Q2 of comparator OP2 output end, and grid is connected to the metal-oxide-semiconductor Q1 of comparator OP2 output end by NOT gate,
One end connect with the source electrode of the drain electrode of metal-oxide-semiconductor Q1 and metal-oxide-semiconductor Q2 respectively, the capacitor C1 of the source electrode connection of the other end and metal-oxide-semiconductor Q1,
And inverting input terminal is connected to the comparator OP3 of the drain electrode of metal-oxide-semiconductor Q2, the drain electrode of the metal-oxide-semiconductor Q2 is connected with current source I1,
Voltage source U1 is connected between the normal phase input end of the comparator OP3 and the source electrode of metal-oxide-semiconductor Q1, the comparator OP3's is defeated
Outlet is connect with the end D of d type flip flop D1, and the normal phase input end of described comparator OP1, OP2 are connect with Vds, the comparator
The inverting input terminal of OP1 loads threshold voltage vt h1, and the inverting input terminal of the comparator OP2 loads threshold voltage vt h2.
4. a kind of SR avoiding improper opening control method according to claim 2, which is characterized in that in step (b2), detect on Vds
The circuit for rising time and fall time includes concatenated switch K1 and K2, and one end is connected on the tie point of switch K1 and K2, is another
The capacitor C2 of one end ground connection, normal phase input end is connected on the tie point of switch K1 and K2, inverting input terminal passes through voltage source U2
The end comparator OP4, D of ground connection is connected to the d type flip flop D2 of comparator OP4 output end, and the other end of the switch K1 is connected with
Current source I2, the other end of the switch K2 are grounded by current source I3.
5. a kind of SR avoiding improper opening control method according to claim 4, which is characterized in that in parallel useful on the capacitor C2
In the switch K3 for resetting the voltage on capacitor C2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910739236.XA CN110445403B (en) | 2019-08-12 | 2019-08-12 | SR false-open prevention control method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910739236.XA CN110445403B (en) | 2019-08-12 | 2019-08-12 | SR false-open prevention control method |
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| CN110445403A true CN110445403A (en) | 2019-11-12 |
| CN110445403B CN110445403B (en) | 2021-04-20 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112865541A (en) * | 2021-01-22 | 2021-05-28 | 成都启臣微电子股份有限公司 | Synchronous rectification controller, synchronous rectification system and synchronous rectification control method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101588137A (en) * | 2008-05-23 | 2009-11-25 | 尼克森微电子股份有限公司 | Synchronous rectification controlling device and forward synchronous converter |
| CN105978341A (en) * | 2016-06-01 | 2016-09-28 | 西安矽力杰半导体技术有限公司 | Secondary side control circuit, secondary side control method, and fly-back converter adopting the same |
| CN106941321A (en) * | 2017-03-22 | 2017-07-11 | 深圳市稳先微电子有限公司 | A kind of control circuit of synchronous rectifier |
-
2019
- 2019-08-12 CN CN201910739236.XA patent/CN110445403B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101588137A (en) * | 2008-05-23 | 2009-11-25 | 尼克森微电子股份有限公司 | Synchronous rectification controlling device and forward synchronous converter |
| CN105978341A (en) * | 2016-06-01 | 2016-09-28 | 西安矽力杰半导体技术有限公司 | Secondary side control circuit, secondary side control method, and fly-back converter adopting the same |
| CN106941321A (en) * | 2017-03-22 | 2017-07-11 | 深圳市稳先微电子有限公司 | A kind of control circuit of synchronous rectifier |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112865541A (en) * | 2021-01-22 | 2021-05-28 | 成都启臣微电子股份有限公司 | Synchronous rectification controller, synchronous rectification system and synchronous rectification control method |
| CN112865541B (en) * | 2021-01-22 | 2022-03-29 | 成都启臣微电子股份有限公司 | Synchronous rectification controller, synchronous rectification system and synchronous rectification control method |
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Address after: Room 214, No.1000 Chenhui Road, China (Shanghai) pilot Free Trade Zone, Pudong New Area, Shanghai, 200120 Patentee after: Shanghai Nanxin Semiconductor Technology Co.,Ltd. Address before: Room 309, 22 Boxia Road, China (Shanghai) pilot Free Trade Zone, Pudong New Area, Shanghai, 200120 Patentee before: SOUTHCHIP SEMICONDUCTOR TECHNOLOGY (SHANGHAI) Co.,Ltd. |