CN103546036A - Control method and control device for switch type power supply - Google Patents
Control method and control device for switch type power supply Download PDFInfo
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- CN103546036A CN103546036A CN201210241626.2A CN201210241626A CN103546036A CN 103546036 A CN103546036 A CN 103546036A CN 201210241626 A CN201210241626 A CN 201210241626A CN 103546036 A CN103546036 A CN 103546036A
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Abstract
Disclosed are a control method and a control device for a switch type power supply. According to an embodiment, the control method for driving current and the relevant control device are applicable to the switch type power supply. The control device comprises a driving circuit and a signal converter, wherein the driving circuit is used for providing driving current to a current control element; the signal converter generates a control signal according to circulation current flowing through the current control element; the driving current is generated according to the control signal; and when the circulation current is increased, the control signals and the driving current are also increased.
Description
Technical field
The present invention relates to switch type power supplying device, especially adopt the switch type power supplying device of current controling element.
Background technology
Switch type power supplying device adopts power switch (power switch), controls the size of current of the inductance element of flowing through.Compared to other power supply unit, switch type power supplying utensil has the energy conversion efficiency that volume is little and good, so be extensively subject to the employing of power supply industry instantly.
In the power switch of numerous kinds, two junction transistors (bipolar junction transistor, BJT) are because simple in structure, price is cheap and have lower conducting loss, so in the market of low price, occupy the ground of a seat.But compared to metal-oxide semiconductor (MOS) (metal-oxide-semiconductor, MOS) transistor, BJT is a kind of current controling element, need to there is current control device to control the base current of BJT (base current) I
b.Base current I
bmeeting and collected current (collector current) I
cafter merging together, become emitter current (emitter current, I
e).Therefore, emitter current I
epossibly cannot be simple reflect collected current I
c.This may cause switch type power supplying device in Current Control, the disappearance of precision.And precision always is one of target that power supply unit industry is pursued.On the other hand, (switching speed) is slow compared with the switching speed of MOS transistor for the switching speed of BJT, and how high-speed switch BJT is also one of upper emphasis of considering of design.
In this specification, there is identical numbered elements or device, for thering is identical or element or the device of similar functions, structure or characteristic, for people in the industry can learn or know by inference with the instruction of this specification of tool, but uninevitable identical completely.For succinct cause, can repeat specification.
Summary of the invention
Embodiments of the invention disclose a kind of control method that is applicable to a switch type power supplying device.This switch type power supplying device includes a current controling element.This control method includes: provide a drive current, to drive this current controling element; A flow through circulating current of this current controling element of detection; And, according to this circulating current, control this drive current.When this circulating current increases, this drive current increases.
Embodiments of the invention disclose a kind of control device, in order to drive a current controling element.This control device includes one drive circuit and a signal converter.This drive circuit is in order to provide a drive current to this current controling element.This signal converter, according to a circulating current of this current controling element of flowing through, produces a control signal.This drive current produces according to this control signal.When this circulating current increases, this control signal and this drive current all increase.
Embodiments of the invention disclose a kind of control method of cut-off period, are applicable to one drive circuit.This drive circuit has a high-side driver and a low-end driver, jointly drives a power switch.This control method includes: keep this low-end driver to close, with this high-side driver, open this power switch; This high-end and this low-end driver are all closed, make this drive circuit enter this cut-off period; After this cut-off period, keep this high-side driver to close, with this low-end driver, close this power switch; And, according to a circulating current of this power switch of flowing through, decide the time span of this cut-off period.
Embodiments of the invention disclose a kind of control device, in order to drive a power switch.This control device includes one drive circuit, a logic control element and a mode of operation controller.This drive circuit includes a high-side driver and a low-end driver.This high-side driver is in order to open this power switch, and this low-end driver is in order to close this power switch.This logic control element is controlled this drive circuit.This mode of operation controller is coupled to this logic control element.This mode of operation controller, according to a circulating current of this power switch, decides the time span of a cut-off period.In this cut-off period, this high-end and this low-end driver are closed condition, do not drive this power switch.
Accompanying drawing explanation
The switch type power supplying device of Fig. 1 for implementing according to the present invention.
Fig. 2 given an example a pulse-width modulator, a BJT and a current sense resistor.
Fig. 3 shows some signal timing diagrams in Fig. 2.
[main element symbol description]
10 switch type power supplying devices
12 bridge rectifiers
14 transformers
16 diodes
18 output capacitances
20 pulse-width modulators
21 clock generators
22 current sense resistors
23 loads
24 operational amplifiers
26 trsanscondutors
27 current generators
28 BJT drivers
30 high-side driver
32 low-end drivers
34 logic control elements
35 mode of operation controllers
36,38 comparators
AC electric main
COM compensates end
I
bbase current
I
ccollected current
I
ddrift current
I
eemitter current
I
lEBdefault fixed value
I
oFFSETdefault bias value
I
rproportional current
PRM primary side winding
S
cLKclock signal
SEC primary side winding
S
hhigh-side signal
S
llow-side signal
T
0, t
1, t
2, t
3, t
4time point
T
dEADthe cut-off period
T
lDthe Linear Driving period
T
lEBthe period is hidden from view in rising edge
T
oFFclose the period
T
oNopen the period
T
S BJT
V
bIASdefault bias voltage
V
cOMbucking voltage
V
cScurrent detection voltage
V
lineaC line power supply
V
oUTout-put supply
V
targettarget voltage
Embodiment
The switch type power supplying device of Fig. 1 for implementing according to the present invention.Although switch type power supplying device 10 is a flyback power converter (flyback converter), the present invention is not limited to this framework.For instance, the present invention also goes for step-down controller (buck converter) and booster converter (boost converter).
Current detection voltage V on current sense resistor 22
cSrepresented emitter current I
e.As the BJT T that flows through
scollected current I
cmuch larger than base current I
btime, emitter current I
ealso be exactly approximately primary side winding PRM and BJT T
scirculating current.Pulse-width modulator (pulse width modulator) 20 is by current detection voltage V
cS, detect BJT T
scirculating current.According to bucking voltage V
cOMwith current detection voltage V
cS, pulse-width modulator 20 modulation BJT T
soperating time.The modulation system of operating time may be about fixed switching frequency and modulate BJT T
sopening time or shut-in time; Also may be approximately fixedly opening time or shut-in time, and modulation BJT T
sswitching frequency.For instance, in one embodiment, along with bucking voltage V
cOMrising, pulse-width modulator 20 makes BJT T
sswitching frequency and opening time all increase.
Fig. 2's pulse-width modulator 20, BJT T has given an example
sand current sense resistor 22.In pulse-width modulator 20, there are clock generator 21, current generator 27, trsanscondutor (transconductor is referred to as again " transducer ") 26, BJT driver 28, logic control element 34 and mode of operation controller 35.
Clock generator 21 is according to bucking voltage V
cOMmagnitude of voltage, periodic clock signal S is provided
cLK, periodically open BJT T
s.BJT driver 28 has high-side driver (high-side driver) 30 and low-end driver 32, together drives BJT T
s.High-side driver 30 can provide drive current with low-end driver 32, draws high respectively or reduces BJT T
sbase voltage.Trsanscondutor 26 can be used as a signal converter, and it is according to current detection voltage V
cSproduce proportional current I
r.In this embodiment, I
r=g
m* V
cS, g wherein
mtransconductance value (transconductance is referred to as again " transduction value ") for trsanscondutor 26.Current generator 27 is by clock signal S
cLKinstitute triggers, and drift current I is provided
d, its value changed along with the time, will be in explanation after a while.Proportional current I
rwith drift current I
dtogether flow to high-side driver 30.Logic control element 34 subject clock signal S
cLKinstitute triggers, and periodically with high-side driver 30, makes BJT T
sopen, enter conducting state.Logic control element 34 is with high-side signal S
hopen or close high-side driver 30, with low-side signal S
lopen or close low-end driver 32.
As shown in Figure 2, mode of operation controller 35 has two comparators 36 and 38.Comparator 38 is bucking voltage V relatively
cOMwith current detection voltage V
cS; One input of comparator 36 receives bucking voltage V
cOM, other end received current detects voltage V
cSwith a default bias voltage V
bIASclose.Described in previously, current detection voltage V
cSrepresented the BJT T that flows through
semitter current I
e.Therefore,, from the angle of electric current, that comparator 38 compares is emitter current I
ewith bucking voltage V
cOMone current offset values of representative, that comparator 36 compares is emitter current I
ewhether surpass this current offset values and deduct default bias voltage V
bIASone preset value of representative.
Fig. 3 shows some signal timing diagrams in Fig. 2.From top to bottom, be respectively sequentially clock signal S
cLK, high-side signal S
h, low-side signal S
l, current detection voltage V
cS, base current I
b, and drift current I
d.Below explanation please also refer to Fig. 2.
At time point t
0, clock signal S
cLKfirst make low-side signal S
lfor in logic 0, then make high-side signal S
hfor in logic 1, as shown in Figure 3.In other words, first allow low-end driver 32 remain on closed condition, then just with high-side driver 30, open BJT T
s.Current detection voltage V now
cSstart to be greater than 0, have the suitable electric current BJT T that flows through
sso, BJT T
senter and open period T
oN.BJT T
senter and open period T
oNthe one section of preset period of time starting afterwards, is commonly referred to as rising edge and hides from view the period (leading edge blanking period) T
lEB, as time point t in Fig. 3
0to t
1shown in.Period T is hidden from view in rising edge
lEBin, the drift current I that current generator 24 produces
dbe a sizable default fixed value I
lEB.High-side driver 30 is only with drift current I
dbe used as drive current, drive BJT T
s.
Along with period T is hidden from view in rising edge
lEBfinish, from time point t
1start drift current I
dbecome a smaller default bias value I
oFFSET.Now, high-side driver 30 is with proportional current I
rwith drift current I
dsummation, as drive current, drive BJT T
s.
At time point t
2, current detection voltage V
cSexceeded bucking voltage V
cOMdeduct default bias voltage V
bIAS, so comparator 36 transitions, logic control element 34 makes high-side signal S
htransition is 0.High-side driver 30 stops providing drive current to BJT T
sso, base current I
bbecome and be almost 0.Time point t
1to time point t
2between can be called Linear Driving period T
lD.In section, be used for driving BJT T at this moment
sbase current I
baccording to current detection voltage V
cSand produce, and, base current I
balong with current detection voltage V
cSincrease and increase.At Linear Driving period T
lDin, base current I
bexceed proportional current I
rapproximately there is fixing default bias value I
oFFSET, as shown in Figure 3.
From time point t
2the a period of time starting, high-side driver 30 is all closed with low-end driver 32, does not drive BJT T
s, base current I
bbe almost 0, can be called cut-off period T
dEAD, as time point t in Fig. 3
2to t
3shown in.At cut-off period T
dEADat the beginning, current detection voltage V
cSreduce, reacted base current I
bunexpected disappearance.Afterwards, because BJT is T
sbase stage also have residual electric charge by BJT T
semitter-base bandgap grading take away, so current detection voltage V
cSor can raise.
At time point t
3, current detection voltage V
cSexceeded bucking voltage V
cOM, so comparator 38 transitions, logic control element 34 makes low-side signal S
ltransition is 1, and makes high-side signal S
hbe maintained 0.Now, high-side driver 30 is closed, and low-end driver 32 drives BJT T
sbase stage, close BJTT
s.For instance, now low-end driver 32 directly by BJT T
sbase earth, so base current I
bbecome a sizable negative value suddenly.BJT T
sbase voltage move to and be 0 after, base current I
bjust very fast reply is 0, as shown in Figure 3.
At time point t
3the time point t starting to next switch periods
4in, high-side signal S
hbe 0, low-side signal S
lbe 1, high-side driver 30 is closed, and low-end driver 32 is BJT T
sbase earth.This period of time can be called BJT T
sclose period T
oFF.Now, BJT T
sfor buttoned-up status, current detection voltage V
cSbe approximately 0, almost do not have electric current to flow through BJT T
s.
With respect to closing period T
oFF, at time point t
0to t
3between period can be called BJT T
sunlatching period T
oN, have the suitable circulating current BJT T that flows through
s.Open period T
oNby rising edge, hide from view period T
lEB, Linear Driving period T
lD, and cut-off period T
dEADinstitute forms.
In one embodiment, default bias voltage V
bIASit is a fixed value.In another embodiment, default bias voltage V
bIASby bucking voltage V
cOMthe decision of controlling.For example, bucking voltage V
cOMhigher, default bias voltage V
bIASjust higher.
From the introduction of Fig. 2 and Fig. 3, can learn that the embodiment of Fig. 2 has following advantage.
1. power saving: at Linear Driving period T
lDin, base current I
bonly exceed proportional current I
rapproximately there is default bias value I
oFFSET, and this default bias value I
oFFSETthat can design enough maintains BJT T
sconducting state in saturated (saturate) is just passable.In other words, default bias value I
oFFSETdo not need excessive, so the power saving that the BJT driver 28 of Fig. 2 can be suitable.
2. high-speed switch speed: hide from view period T in rising edge
lEB, base current I
bbe exactly approximately very large preset value I
lEB.Large base current I like this
b, can be fast by BJT T
sfrom closed condition, be switched to fast saturated conducting state.High-speed switch speed also can reduce switching loss, improves energy conversion efficiency.
3. accurate current detecting: opening period T
oNthe time point t finishing
3time, because base current I
bbe 0, so current detection voltage V
cSor emitter current I
ecan be more accurate represent collected current I
c, the electric current of the primary side winding PRM of the transformer of namely flowing through.Also therefore, adopt time point t
3time current detection voltage V
cSdo Current Control, can obtain result more accurately.
4. end period T
dEADtime span is variable: cut-off period T
dEADtime span is according to current detection voltage V
cSand default bias voltage V
bIASand determine.Briefly, cut-off period T
dEADtime span be current detection voltage V
cSincreased default bias voltage V
bIASthe required time.AC line power supply V
linehigher, current detection voltage V
cSgather way also just faster, so cut-off period T
dEADshorter.In one embodiment, default bias voltage V
bIASalong with bucking voltage V
cOMand change.Because bucking voltage V
cOMthat corresponding is the out-put supply V that hangs over primary side
oUTon output loading, cut-off period T
dEADwill change along with output loading.
The foregoing is only the preferred embodiments of the present invention, all equalizations of doing according to the claims in the present invention book change and modify, and all should belong to covering scope of the present invention.
Claims (24)
1. be applicable to a control method for a switch type power supplying device, this switch type power supplying device includes a current controling element, and this control method includes:
Provide a drive current, to drive this current controling element;
A flow through circulating current of this current controling element of detection; And
According to this circulating current, control this drive current;
Wherein, when this circulating current increases, this drive current increases.
2. control method as claimed in claim 1, also includes:
Produce a proportional current, this proportional current equal proportion is in this circulating current;
Wherein, this drive current and this proportional current differ a fixing deviant roughly.
3. control method as claimed in claim 1, wherein, also includes:
In the scheduled time after this current controling element is unlocked, making this drive current is a default fixed value.
4. control method as claimed in claim 1, also includes:
When this circulating current surpasses an offset, this current controling element is closed completely.
5. control method as claimed in claim 1, also includes:
One clock signal is provided, periodically makes this current controling element be unlocked.
6. a control device, in order to drive a current controling element, includes:
One drive circuit, in order to provide a drive current to this current controling element; And
One signal converter, the circulating current according to this current controling element of flowing through, produces a control signal;
Wherein, this drive current produces according to this control signal; And
When this circulating current increases, this control signal and this drive current all increase.
7. control device as claimed in claim 6, wherein, this signal converter is a trsanscondutor (transconductor), according to a current detection voltage, produces a proportional current, this current detection voltage ratio is in this circulating current.
8. control device as claimed in claim 7, wherein, this drive current and this proportional current differ a fixing deviant roughly.
9. control device as claimed in claim 7, wherein, this drive circuit includes a high-side driver (high-side driver), according to this proportional current and a drift current, produces this drive current.
10. control device as claimed in claim 6, also include a logic control element and a low-end driver (low-side driver), when this circulating current surpasses an offset, this logic control element makes this low-end driver close this current controling element.
11. control device as claimed in claim 10, wherein, this offset is controlled by a power supply Output rusults of a switch type power supplying device.
A kind of control method of 12. cut-off periods, is applicable to one drive circuit, and this drive circuit has a high-side driver and a low-end driver, jointly drives a power switch, and this control method includes:
Keep this low-end driver to close, with this high-side driver, open this power switch;
This high-end and this low-end driver are all closed, make this drive circuit enter this cut-off period;
After this cut-off period, keep this high-side driver to close, with this low-end driver, close this power switch; And
According to a circulating current of this power switch of flowing through, decide the time span of this cut-off period.
13. control methods as claimed in claim 12, include:
When this circulating current surpasses an offset, with this low-end driver, close this power switch.
14. control methods as claimed in claim 13, include:
When this circulating current deducts a preset value over an offset, close this high-end and this low-end driver, make this drive circuit enter this cut-off period.
15. control methods as claimed in claim 14, include:
According to this offset, determine this preset value.
16. control methods as claimed in claim 12, wherein, this controlling party genealogy of law is applicable to a switch type power supplying device, and it receives an input line power supply, and this time span of this cut-off period shortens along with the rising of this input line power supply.
17. control methods as claimed in claim 12, wherein, this time span system of this cut-off period is relevant to an offset, and this offset is controlled by a power supply Output rusults of a switch type power supplying device.
18. 1 kinds of control device, in order to drive a power switch, include:
One drive circuit, includes:
One high-side driver, in order to open this power switch; And
One low-end driver, in order to close this power switch;
One logic control element, controls this drive circuit; And
One mode of operation controller, is coupled to this logic control element, and this mode of operation controller, according to a circulating current of this power switch, decides the time span of a cut-off period;
Wherein, in this cut-off period, this high-end and this low-end driver are closed condition, do not drive this power switch.
19. control device as claimed in claim 18, wherein, this mode of operation controller includes:
One comparator, in order to relatively this circulating current and an offset;
When this circulating current exceeds after this offset, this logic control element is closed this power switch with this low-end driver, finishes this cut-off period.
20. control device as claimed in claim 18, wherein, when this circulating current exceeds an offset and deducts a preset value, this logic control element is closed this high-end and this low-end driver, makes this drive circuit enter this cut-off period.
21. control device as claimed in claim 20, wherein, this offset is controlled by a power supply Output rusults of a switch type power supplying device.
22. control device as claimed in claim 20, wherein, this offset is controlled by a power supply Output rusults of a switch type power supplying device, and this preset value is decided by this offset.
23. control device as claimed in claim 18, wherein, this power switch is a current controling element.
24. control device as claimed in claim 18, wherein, this control device also includes a clock apparatus, periodically makes this high-side driver open this power switch.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210241626.2A CN103546036B (en) | 2012-07-12 | 2012-07-12 | The control method of switch type power supplying device and control device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210241626.2A CN103546036B (en) | 2012-07-12 | 2012-07-12 | The control method of switch type power supplying device and control device |
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| CN103546036B CN103546036B (en) | 2016-12-21 |
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| US20040032288A1 (en) * | 2002-08-14 | 2004-02-19 | International Rectifier Corp. | Driver IC for use with simple microcontrol |
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| Publication number | Publication date |
|---|---|
| CN103546036B (en) | 2016-12-21 |
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