CN105244848B - Over-voltage protection method and circuit - Google Patents
Over-voltage protection method and circuit Download PDFInfo
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- CN105244848B CN105244848B CN201510728744.XA CN201510728744A CN105244848B CN 105244848 B CN105244848 B CN 105244848B CN 201510728744 A CN201510728744 A CN 201510728744A CN 105244848 B CN105244848 B CN 105244848B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
Abstract
The present invention provides a kind of over-voltage protection method and circuit, and over-voltage protection method includes: the descending slope for obtaining inductive current after switching tube shutdown in overvoltage crowbar, and descending slope is directly proportional to the output voltage of circuit.By the descending slope of acquisition, threshold value is compared compared with, when descending slope, which is greater than, compares threshold value, output voltage over-voltage.When output voltage over-voltage, pipe is turned off the switch, does not continue to be damaged when effectivelying prevent being supported on over-voltage for load supplying.
Description
Technical field
The present invention relates to electronic technology fields, and in particular to a kind of over-voltage protection method and circuit.
Background technique
In existing translation circuit, as usually passed through directly sampling output electricity in Buck circuit (Buck conversion circuit)
Pressure is to realize overvoltage protection.As shown in Figure 1, switching tube is connected with the positive bus-bar of Buck circuit, the source electrode connection two of switching tube
One of input terminal of pole pipe, comparator directly acquires output voltage by divider resistance, after comparison through logic control
The control electrode to switching tube is exported to realize overvoltage protection.In this each circuit, since the source electrode of switching tube connects diode, therefore open
Close the V of pipeGSCurrent potential is not fixed, and switching tube needs drive floatingly, is driven complex.
For convenience of driving, switching tube is connected with the negative busbar of Buck circuit, as shown in Figure 2.In the circuit due to
Output voltage and input voltage altogether, do not need to realize output voltage in switching tube conducting by an auxiliary winding
Sampling, and then realize overvoltage protection.Increase complexity and cost that auxiliary winding not only increases route, and auxiliary winding
It is a negative voltage during switch conduction, is unfavorable for being internally integrated for circuit.
Summary of the invention
The present invention for overcome the deficiencies in the prior art, provides a kind of over-voltage protection method and circuit.
To achieve the goals above, the present invention provides a kind of over-voltage protection method and includes:
Obtain the descending slope of inductive current after switching tube shutdown in overvoltage crowbar, the output of descending slope and circuit
Voltage is directly proportional；
By the descending slope of acquisition, threshold value is compared compared with, when descending slope, which is greater than, compares threshold value, output voltage
Over-voltage；
When output voltage over-voltage, pipe is turned off the switch.
In one embodiment of the invention, the preparation method of descending slope are as follows:
Current change quantity △ i of the inductive current from peak-fall to valley is obtained after switching tube shutdown；
Obtain fall time △ t of the inductive current from peak-fall to valley；
Descending slope are as follows: △ i/ △ t；
Descending slope is compared with descending slope threshold value, when descending slope is greater than descending slope threshold value, output electricity
It presses through.
In one embodiment of the invention, when the peak value that inductive current is critical continuous conduction mode and inductive current is constant, or electricity
When inducing current is constant for the peak value of discontinuous mode and inductive current, descending slope is converted to obtains inductance electricity after switching tube shutdown
Stream is from peak-fall to zero fall time △ t, and fall time △, t was inversely proportional with output voltage.
In one embodiment of the invention, when inductive current is continuous mode, the turn-off time of switching tube is equal to inductance electricity
The fall time of stream, the acquisition of descending slope is converted to obtains inductive current from peak-fall to valley after switching tube shutdown
The ratio of current change quantity △ i and switching tube turn-off time, the ratio are directly proportional to output voltage.
Corresponding with above-mentioned over-voltage protection method, the present invention also provides a kind of overvoltage crowbars, including load, electricity
Sense, switching tube, freewheeling diode, descending slope acquiring unit, threshold setting unit, judging unit and protection location.Load, electricity
Sense and switching tube are sequentially connected in series in circuit output end.Freewheeling diode is connected between load and inductance, inductance, afterflow two
Discharge loop is formed between pole pipe and load, when switching tube shutdown, inductance is discharged by discharge loop.Descending slope obtains single
Member obtains the descending slope of inductive current after switching tube shutdown, and descending slope is directly proportional to output voltage.Threshold setting unit is set
Surely compare threshold value and be electrically connected judging unit.Judging unit is electrically connected descending slope acquiring unit and threshold setting unit,
By the descending slope of characterization circuit output voltage and compare threshold value and be compared, according to the output voltage of comparison result decision circuitry
Whether over-voltage.Protection location is electrically connected judging unit and switching tube, and when judging unit judges output voltage over-voltage, protection is single
Member turns off the switch pipe.
In one embodiment of the invention, descending slope acquiring unit include current change quantity sampling unit, timing unit and
Inductance and timing unit is electrically connected in computing unit, current change quantity sampling unit, and current change quantity sampling unit obtains
Current change quantity of the inductive current from peak-fall to valley, timing unit start timing at the switching tube shutdown moment, work as inductance
Timing terminates when electric current drops to valley, obtains fall time, current change quantity and fall time export to computing unit, through counting
Descending slope is obtained after calculation, descending slope is exported to judging unit and compared with the descending slope threshold value of setting by computing unit
Compared with, when descending slope is greater than descending slope threshold value, output voltage over-voltage.
In one embodiment of the invention, when inductive current is critical continuous conduction mode or discontinuous mode, descending slope is obtained
Unit includes zero passage detection unit, time switch, DC source and charging capacitor, and zero passage detection unit is electrically connected inductance, is obtained
For inductance at the time of electric current drops to zero point during discharge, time switch is electrically connected zero passage detection unit, closes in switching tube
Disconnected moment time switch closure, DC source charge to charging capacitor, and when inductive current drops to zero point, time switch is beaten
It opens, capacitor charging terminates；
Threshold setting unit includes peak point current sampling resistor, holding unit and proportional unit, peak point current sampling resistor
It is electrically connected switching tube, the peak point current on inductance is obtained in switching tube shutdown and enters proportional unit progress ratio after keeping
Calculating forms voltage threshold；
When DC source is formed by capacitance voltage less than voltage threshold to capacitor charging within inductive current fall time,
Output voltage over-voltage.
In one embodiment of the invention, when inductive current is constant for the peak value of critical continuous conduction mode and inductive current, or
When inductive current is constant for the peak value of discontinuous mode and inductive current, descending slope acquiring unit includes zero passage detection unit and meter
Shi Danyuan, zero passage detection unit are electrically connected inductance, obtain inductance at the time of electric current drops to zero point during discharge, timing
Unit is electrically connected zero passage detection unit, starts timing in switching tube shutdown moment timing unit, drops to zero in inductive current
Timing terminates after point, obtains the fall time of inductive current and will export fall time to judging unit, carries out with time threshold
Compare.
In one embodiment of the invention, zero passage detection unit includes and the concatenated current sampling resistor of inductance and detecting current
The detecting voltage unit of sampling resistor both end voltage, detecting voltage unit after current sampling resistor both end voltage drops to zero point
Output signal to timing unit or time switch.
In one embodiment of the invention, zero passage detection unit includes differential capacitance, differential resistance and negative voltage detecting unit,
Differential capacitance is connected on the intersection point of switching tube and inductance, and differential resistance is connected with differential capacitance and differential resistance is grounded, negative electricity
The negative voltage at detecting unit detecting differential capacitance and differential resistance tie point is pressed, negative voltage detecting unit is electrically connected timing list
Member or time switch, once negative voltage detecting unit detects that negative voltage, timing unit or time switch stop timing.
In conclusion over-voltage protection method provided by the invention and circuit have the advantage that compared with prior art
Inductance is a kind of energy-storage travelling wave tube, after switching tube shutdown, inductance during discharge the descending slope of inductive current with
The output voltage of circuit is directly proportional.The present invention utilizes this characteristic of inductance, and setting descending slope acquiring unit obtains inductance electricity
Flow the descending slope after switching tube shutdown.By descending slope, the threshold value compared with is compared judging unit, by comparing result
Judge whether over-voltage does not continue to once output voltage over-voltage, protection location turn off the switch pipe as load supplying output voltage,
Protect output loading.Over-voltage protection method and circuit provided by the invention utilize inductive discharge when inductive current descending slope with
Relationship between output voltage obtains output voltage indirectly, to realize the judgement of output overvoltage.This kind of sample mode, switch
Pipe is sampled without driving and winding without use floatingly, and not only circuit structure is simple and each inductance, inductance sampling unit
Equal components can be integrated with output circuit, substantially reduce the volume of circuit.
For above and other objects of the present invention, feature and advantage can be clearer and more comprehensible, preferred embodiment is cited below particularly,
And cooperate attached drawing, it is described in detail below.
Detailed description of the invention
Fig. 1 and Fig. 2 show the schematic diagram of existing overvoltage crowbar.
Fig. 3 show the schematic diagram of the overvoltage crowbar of the offer of the embodiment of the present invention one.
Fig. 4 show the flow chart of the over-voltage protection method of the offer of the embodiment of the present invention one.
Fig. 5 show the flow chart of step S1 in Fig. 4.
Fig. 6 show the schematic diagram of overvoltage crowbar provided by Embodiment 2 of the present invention.
Fig. 7 show another embodiment of the present invention provides overvoltage crowbar schematic diagram.
Fig. 8 show the flow chart of over-voltage protection method provided by Embodiment 2 of the present invention.
Fig. 9 show the schematic diagram of the overvoltage crowbar of the offer of the embodiment of the present invention three.
Figure 10 show the curent change figure of critical current mode continuous mode.
Figure 11 show the curent change figure of discontinuous mode.
Specific embodiment
Embodiment one
Fig. 1 show existing Buck circuit and realizes overvoltage protection by direct sampling and outputting voltage, in the circuit
Due to the V of switching tubeGSDriving voltage and control chip not altogether, therefore need to be using driving floatingly.And in Fig. 2, switching tube
Driving and controlling circuits altogether, but export not altogether, need to realize overvoltage protection by increasing auxiliary winding, this is not only significantly
Cost is increased, while being also unfavorable for being internally integrated for circuit.
In view of this, as shown in figure 4, over-voltage protection method provided in this embodiment includes:
Step S1, the descending slope △ i/ △ t of inductive current after switching tube shutdown in overvoltage crowbar, lower drop angle are obtained
The output voltage U of rate △ i/ △ t and circuitoutIt is directly proportional, Uout=L △ i/ △ t, L are inductance, and △ i is electricity after switching tube shutdown
Current change quantity of the inducing current from peak-fall to valley, △ t are time of the inductive current from peak-fall to valley.
In this present embodiment, step S1 includes:
Step S11, current change quantity △ i of the inductive current from peak-fall to valley is obtained after switching tube shutdown.In
In the present embodiment, current change quantity △ i is obtained using current change quantity sampling unit 11, current change quantity sampling unit 11 wraps
It includes and the concatenated current sampling resistor of inductance, comparator, memory and processor.When inductive current is in peak value, electric current is adopted
There is maximum voltage U on sample resistancemax, when inductive current drops to valley, there is minimum voltage U on current sampling resistormin。
Memory stores the sampled value on current sampling resistor, and the constantly more two neighboring sampled value of comparator obtains maximum voltage Umax
With minimum voltage Umin, maximum voltage UmaxWith minimum voltage UminCurrent change quantity △ i=(U is obtained after processor calculatesmax-
Umin)/R1, R1 are the resistance value of current sampling resistor.
Step S12, fall time △ t of the inductive current from peak-fall to valley is obtained.For inductance, switching tube
The immediate current of shutdown is in peak value, and in this present embodiment, timing unit starts timing when switching tube turns off, when comparator ratio
Relatively obtain minimum voltage UminAnd by minimum voltage UminIt exports to processor, output signal of processor to timing unit 12, timing
Unit 12 terminates timing and obtains time △ t of the inductive current from peak-fall to valley.
Step S13, by △ i/ △ t, inductive current descending slope K is obtained.
Step S2, by the descending slope K of acquisition compared with threshold krefIt is compared, compares threshold value when descending slope K is greater than
KrefWhen, output voltage UoutOver-voltage.
Step S3, when output voltage over-voltage, protection location turns off the switch pipe, does not continue to as load supplying.
It is corresponding with above-mentioned over-voltage protection method, as shown in figure 3, the present invention also provides a kind of overvoltage crowbars to include
It loads R, inductance L, switching tube Q, sustained diode, descending slope acquiring unit 1, threshold setting unit 2, judging unit 3 and protects
Protect unit 4.Load R, inductance L and switching tube Q three are sequentially connected in series.Sustained diode be connected to load R and inductance L it
Between, discharge loop is formed between inductance L, sustained diode and load R, when switching tube Q shutdown, inductance L passes through discharge loop
Electric discharge.Descending slope acquiring unit 1 obtains the descending slope K of inductive current after switching tube Q shutdown, descending slope K and output electricity
Press UoutIt is directly proportional.The setting of threshold setting unit 2 compares threshold value and is electrically connected judging unit 3.Judging unit 3 is by characterization circuit
The descending slope K of output voltage and compare threshold krefIt is compared, according to the output voltage U of comparison result decision circuitryoutIt is
No over-voltage.Protection location 4 is electrically connected judging unit 3 and switching tube Q, when judging unit 3 judges output voltage over-voltage, protection
Unit 4 turns off the switch pipe Q, does not continue to as load supplying.
In this present embodiment, descending slope acquiring unit 1 includes current change quantity sampling unit 11, timing unit 12 and meter
Unit 13 is calculated, inductance L and timing unit 12, current change quantity sampling unit is electrically connected in current change quantity sampling unit 11
11 obtain current change quantity of the inductive current from peak-fall to valley, and timing unit 12 starts to count at the switching tube shutdown moment
When, when inductive current drops to valley, timing terminates, and obtains fall time △ t.Current change quantity △ i and fall time △ t
Output obtains descending slope K to computing unit 13 after being computed, computing unit 13 by descending slope K export to judging unit 3 with
The descending slope threshold k of settingrefIt is compared, when descending slope K is greater than descending slope threshold krefWhen, output voltage UoutIt crosses
Pressure.
In this present embodiment, current change quantity sampling unit 11 include with the concatenated current sampling resistor of inductance, comparator,
Memory and processor.Memory stores previous sampled value, one of input terminal and the current sample electricity of comparator
Resistance is connected, another input terminal is connected with memory, is obtained by constantly comparing current sample values and previous sampled value
Maximum voltage UmaxWith minimum voltage Umin, current change quantity is obtained after processor is handled.In this present embodiment, judging unit 3
For comparator.
Embodiment two
It is critical continuous conduction mode and peak value electricity that over-voltage protection method and circuit provided in this embodiment, which are suitable for inductive current,
Flow constant or discontinuous mode and the constant circuit of peak point current.It is critical continuous mode mould that inductive current, which is set forth, in Figure 10 and Figure 11
Curent change figure under formula and discontinuous mode.For critical continuous conduction mode, switching tube reaches set electric current in inductive current peak
It turns off when peak threshold, is reopened at the time of inductive current falls to zero；For discontinuous mode, switching tube is in inductive current
Shutdown when peak value reaches set current peak threshold value, after inductive current falls to zero, delay a period of time is reopened.?
In Figure 10 and Figure 11, t0 moment switching tube shutdown, t1 moment inductive current drops to zero, △ i=t1-t0.In critical continuous mode mould
Formula and peak point current IpeakConstant or discontinuous mode and peak point current IpeakIn constant circuit, the electric current on inductance necessarily declines
To zero point, in this kind of circuit, inductive current variable quantity △ i=Ipeak- 0=Ipeak, i.e. △ i is constant.
According to formula K=△ i/ △ t
Since △ i is constant, the acquisition of descending slope K, which is converted to, obtains inductive current from peak IpeakDrop under zero point
Time △ t drops, fall time △ t and descending slope K is inversely proportional, i.e., with output voltage UoutIt is inversely proportional.Therefore, in the present embodiment
In, by descending slope K, the comparison of threshold value is converted to fall time △ t compared with time threshold compared with.Specifically, as schemed
Shown in 8, over-voltage protection method provided in this embodiment includes:
Step S10, fall time △ t of the inductive current from peak-fall to zero is obtained after switching tube shutdown.
Step S20, by fall time △ t and time threshold △ trefIt is compared, when △ t is less than △ trefWhen, output electricity
Press UoutOver-voltage.
Step S30, when output voltage over-voltage, pipe is turned off the switch, is not continued to as load supplying.
It corresponds to the above method, as shown in fig. 6, it includes load R, inductance that the present invention, which provides a kind of overvoltage crowbar,
L, switching tube Q, sustained diode, descending slope acquiring unit 1, threshold setting unit 2, judging unit 3 and protection location 4.It is negative
R, inductance L and switching tube Q three is carried to be sequentially connected in series.Sustained diode is connected between load R and inductance L, inductance L, is continued
Discharge loop is formed between stream diode D and load R, when switching tube Q shutdown, inductance L is discharged by discharge loop.Lower drop angle
Rate acquiring unit 1 obtains the descending slope K, descending slope K and output voltage U of inductive current after switching tube Q shutdownoutIt is directly proportional.
The setting of threshold setting unit 2 compares threshold value and is electrically connected judging unit 3.Judging unit 3 will be under characterization circuit output voltage
Drop angle rate K and compare threshold value and be compared, according to the output voltage U of comparison result decision circuitryoutWhether over-voltage.Protection location 4
It is electrically connected judging unit 3 and switching tube Q, when judging unit 3 judges output voltage UoutWhen over-voltage, protection location 4 is turned off the switch
Pipe Q does not continue to as load supplying.
In this present embodiment, descending slope acquiring unit 1 includes zero passage detection unit 14 and timing unit 12, zero passage detection
Unit 14 is electrically connected inductance L, obtains inductance L at the time of electric current drops to zero point during discharge, and timing unit 12 is electrically
Zero passage detection unit 14 is connected, timing unit 12 starts timing, the meter when inductive current drops to zero point in switching tube Q shutdown
When terminate, obtain the fall time △ t of inductive current and export fall time △ t to judging unit 3, judging unit 3 will under
Time △ t and time threshold △ t dropsrefIt is compared.
In this present embodiment, zero passage detection unit 14 includes and the concatenated current sampling resistor of inductance L, detecting current sampling
The detecting voltage unit of resistance both end voltage, detecting voltage unit exports after current sampling resistor both end voltage drops to zero point
Signal is to timing unit 12.However, the present invention is not limited in any way the structure of zero passage detection unit 14.
In other embodiments, as shown in fig. 7, zero passage detection unit 14 includes differential capacitance C2, differential resistance R2 and bears
Detecting voltage unit T1, differential capacitance C2 are connected on the point of intersection S W point of switching tube Q and inductance L, differential resistance R2 and differential electricity
Hold C2 series connection and differential resistance R2 is grounded, negative voltage detecting unit T1 is detected at differential capacitance C2 and differential resistance R2 tie point
Negative voltage, negative voltage detecting unit T1 are electrically connected timing unit 12.
In switching tube Q shutdown, timing unit 12 starts timing.Before inductive current falls to zero, inductive current is logical
It crosses sustained diode and flows to positive pole line end, SW point voltage is the forward conduction pressure that positive bus-bar end voltage adds sustained diode
Drop, differential capacitance C2 both end voltage are equal to SW point voltage, and the voltage on differential resistance R2 is zero.When inductive current drops to zero
When, sustained diode cut-off is returned by the resonance that the parasitic capacitance of inductance, the parasitic capacitance of sustained diode, switching tube Q form
Road generates resonance at SW point, makes SW voltage start to vibrate to negative busbar end at the time of inductive current falls to zero, in differential
Negative differential electric current is generated on capacitor C2, so that the point of intersection of differential capacitance C2 and differential resistance R2 generate negative voltage.I.e. one
Denier negative voltage detecting unit T1 detect differential capacitance C2 and differential resistance R2 point of intersection be negative voltage when, can assert inductance electricity
Flow down and drop to zero, timing unit 12 stops timing, obtain the fall time △ t of inductive current and by fall time △ t export to
Judging unit 3, judging unit 3 is by fall time △ t and time threshold △ trefIt is compared.
In other embodiments, zero passage detection unit 14 can also for the concatenated intelligent amperemeter of inductance L, when ammeter examine
It measures and outputs signal to timing unit 12 when inductive current is zero.
Embodiment three
As shown in Figure 10 and Figure 11, when inductive current is critical continuous conduction mode or discontinuous mode, inductive current variable quantity
△ i is equal to the peak I of inductive currentpeak.The acquisition of descending slope K, which is converted to, obtains inductive current peak IpeakWith fall time
The ratio of △ t.Inductive current peak IpeakWith the ratio and output voltage U of fall time △ toutIt is directly proportional, therefore, pass through ratio
Compared with inductive current peak IpeakOutput voltage U can be obtained with the ratio of fall time △ toutWhether over-voltage.Once output voltage
UoutOver-voltage then turns off the switch pipe Q, does not continue to as load supplying.
Correspondingly, as shown in figure 9, it is critical continuous conduction mode or discontinuous mode that the present embodiment, which additionally provides a kind of inductive current,
When overvoltage crowbar, including load R, inductance L, switching tube Q, sustained diode, descending slope acquiring unit 1, threshold value set
Order member 2, judging unit 3 and protection location 4.Load R, inductance L and switching tube Q three are sequentially connected in series.Sustained diode
It is connected between load R and inductance L, forms discharge loop between inductance L, sustained diode and load R, when switching tube Q is turned off
When, inductance L is discharged by discharge loop.Descending slope acquiring unit 1 obtains the descending slope of inductive current after switching tube Q shutdown
K, descending slope K and output voltage UoutIt is directly proportional.The setting of threshold setting unit 2 compares threshold value and is electrically connected judging unit 3.
Judging unit 3 is by the inductive current descending slope K of characterization circuit output voltage and compares threshold value and is compared, according to comparison result
The output voltage U of decision circuitryoutWhether over-voltage.Protection location 4 is electrically connected judging unit 3 and switching tube Q, when judging unit 3
When judging output voltage over-voltage, protection location 4 turns off the switch pipe Q, does not continue to as load supplying.
In this present embodiment, descending slope acquiring unit 1 include zero passage detection unit 14, time switch S, DC source I1 and
Charging capacitor C1, zero passage detection unit 14 are electrically connected inductance L, and obtaining inductance L, electric current drops to zero point during discharge
Moment, time switch S are electrically connected zero passage detection unit 14, in switching tube Q shutdown moment time switch S closure, DC source I1
It charges to charging capacitor C1；After inductive current drops to zero point, time switch S is opened, and capacitor C1 charging terminates.
Threshold setting unit 2 includes peak point current sampling resistor R3, holding unit 21 and proportional unit 22, and peak point current is adopted
Sample resistance R3 is electrically connected switching tube Q, obtains the peak I of inductive current in switching tube Q shutdown momentpeak, enter after keeping
22 carry out ratio of proportional unit calculates to form voltage threshold K1*Ipeak, K1 is proportionality constant.Proportional unit 22 can be multiplier.
When DC source I1 is formed by capacitance voltage Uc (Uc=I1* △ t/C1) to capacitor charging in fall time △ t
Less than voltage threshold K1*IpeakWhen, Ipeak/△t>I1/(C1*K1).Due to being critical continuous conduction mode or interrupted mould in inductive current
When formula, inductive current variable quantity △ i is equal to the peak I of inductive currentpeak, therefore △ i/ △ t > I1/ (C1*K1).I1, C1 and K1 are equal
For fixed value, formula identity inductive current descending slope K (△ i/ △ t) is greater than set slope threshold value, output voltage Uout
Over-voltage.
Overvoltage crowbar provided in this embodiment can realize the automatic tune of voltage threshold by Set scale constant K1
It is whole.In actual use, designer can realize over-voltage protection point by replacing the different K1 value of different inductance L or setting
Setting, the setting greatly facilitate the design of circuit and integrate.
In other embodiments, when inductive current is continuous mode, the fall time △ t of inductive current is equal to and opens at this time
Close the turn-off time of pipe.The acquisition of descending slope, which is converted to, obtains inductive current from peak IpeakDrop to valley IvalleyElectricity
Flow the ratio of variable quantity △ i and switching tube turn-off time.The output voltage U of the ratio and circuitoutIt is directly proportional.Therefore, pass through ratio
Compared with the ratio of current change quantity △ i and switching tube turn-off time, can be obtained output voltage whether over-voltage.Once output voltage mistake
Pressure, then turn off the switch pipe Q, do not continue to as load supplying.It in response to this, can be in overvoltage protection electricity provided in this embodiment
It is improved on the basis of road, zero passage detection unit 14, which is replaced with, can detect inductive current peak IpeakWith valley Ivalley
Current change quantity sampling unit.When switching tube is closed, time switch S is closed, and DC source I1 fills charging capacitor C1
Electricity.When inductive current drops to valley IvalleyWhen, time switch S is opened, and is terminated to the charging of charging capacitor C1.
The voltage Uc=I1* △ t/C1 at the both ends charging capacitor C1, when Uc is less than K1* (Ipeak-Ivalley) when, i.e. (Ipeak-
Ivalley)/△ t > I1/ (C1*K1), since I1, C1 and K1 are fixed value, formula identity inductive current descending slope K (△
I/ △ t) it is greater than set slope threshold value, output voltage UoutOver-voltage.
In conclusion inductance is a kind of energy-storage travelling wave tube, after switching tube shutdown, inductance is during discharge under inductive current
Drop angle rate is directly proportional to the output voltage of circuit.The present invention utilizes this characteristic of inductance, and setting descending slope acquiring unit obtains
Take descending slope of the inductance after switching tube shutdown.By descending slope, the threshold value compared with is compared judging unit, by comparing
As a result judge whether over-voltage does not continue to make for load supplying output voltage once output voltage over-voltage, then turn off the switch pipe Q
It obtains and opens a way between output circuit and load, protect output loading.Over-voltage protection method and circuit provided by the invention utilize inductance
Electric discharge when inductive current descending slope and output voltage between relationship come obtain output voltage indirectly, to realize output
The judgement of over-voltage.This kind of sample mode, switching tube are sampled without driving floatingly and without using to wind, not only circuit knot
Structure is simple and the components such as each inductance, inductance sampling unit can be integrated with output circuit, substantially reduces the volume of circuit.
Although the present invention is disclosed above by preferred embodiment, however, it is not intended to limit the invention, this any known skill
Skill person can make some changes and embellishment without departing from the spirit and scope of the present invention, therefore protection scope of the present invention is worked as
Subject to claims range claimed.
Claims (10)
1. a kind of over-voltage protection method characterized by comprising
Obtain the descending slope of inductive current after switching tube shutdown in overvoltage crowbar, the output voltage of descending slope and circuit
It is directly proportional；
By the descending slope of acquisition, threshold value is compared compared with, when descending slope, which is greater than, compares threshold value, output voltage over-voltage；
When output voltage over-voltage, pipe is turned off the switch；
When inductive current is critical continuous conduction mode or inductive current is discontinuous mode, descending slope is obtained single by descending slope
Member obtains, and descending slope acquiring unit includes zero passage detection unit, time switch, DC source and charging capacitor, zero passage detection list
Member is electrically connected inductance, obtains inductance at the time of electric current drops to zero point during discharge, time switch is electrically connected zero passage
Detection unit, in switching tube shutdown moment time switch closure, DC source charges to charging capacitor, when inductive current declines
When to zero point, time switch is opened, and capacitor charging terminates；When DC source within inductive current fall time to capacitor charging institute shape
At capacitance voltage be less than compare threshold value when, output voltage over-voltage.
2. over-voltage protection method according to claim 1, which is characterized in that threshold setting unit includes peak point current sampling
Resistance, holding unit and proportional unit, peak point current sampling resistor are electrically connected switching tube, obtain inductance in switching tube shutdown
On peak point current enter proportional unit after keeping and carry out ratio and calculate to be formed and compare threshold value.
3. a kind of over-voltage protection method characterized by comprising
Obtain the descending slope of inductive current after switching tube shutdown in overvoltage crowbar, the output voltage of descending slope and circuit
It is directly proportional；
By the descending slope of acquisition, threshold value is compared compared with, when descending slope, which is greater than, compares threshold value, output voltage over-voltage；
When output voltage over-voltage, pipe is turned off the switch；
When peak value that inductive current is critical continuous conduction mode and inductive current is constant or inductive current is discontinuous mode and inductance electricity
When the peak value of stream is constant, descending slope is converted to when obtaining inductive current from decline of the peak-fall to zero after switching tube turns off
Between △ t, fall time △, t was inversely proportional with output voltage, and descending slope is obtained by descending slope acquiring unit, descending slope obtain
Unit includes zero passage detection unit and timing unit, and zero passage detection unit is electrically connected inductance, obtains inductance during discharge
At the time of electric current drops to zero point, timing unit is electrically connected zero passage detection unit, opens in switching tube shutdown moment timing unit
Beginning timing, timing terminates after inductive current drops to zero point, obtains the fall time of inductive current and will export fall time
To judging unit, it is compared with time threshold.
4. a kind of overvoltage crowbar characterized by comprising
It is sequentially connected in series load, inductance and switching tube in circuit；
Freewheeling diode is connected between load and inductance, forms discharge loop between inductance, freewheeling diode and load, when
When switching tube turns off, inductance is discharged by discharge loop；
Descending slope acquiring unit, obtains the descending slope of inductive current after switching tube shutdown, descending slope and output voltage at
Direct ratio；
Threshold setting unit, setting compare threshold value and are electrically connected judging unit；
Judging unit is electrically connected the descending slope acquiring unit and threshold setting unit, by characterization circuit output voltage
Descending slope and compare threshold value and be compared, according to the output voltage of comparison result decision circuitry whether over-voltage；
Protection location is electrically connected judging unit and switching tube, and when judging unit judges output voltage over-voltage, protection location is closed
Close switching tube；
When inductive current is critical continuous conduction mode or discontinuous mode, descending slope acquiring unit includes zero passage detection unit, meter
Shi Kaiguan, DC source and charging capacitor, zero passage detection unit are electrically connected inductance, and obtaining inductance, electric current declines during discharge
At the time of to zero point, time switch is electrically connected zero passage detection unit, in switching tube shutdown moment time switch closure, DC source
It charges to charging capacitor, when inductive current drops to zero point, time switch is opened, and capacitor charging terminates；Work as DC source
When being formed by capacitance voltage less than threshold value is compared to capacitor charging within inductive current fall time, output voltage over-voltage.
5. overvoltage crowbar according to claim 4, which is characterized in that threshold setting unit includes peak point current sampling
Resistance, holding unit and proportional unit, peak point current sampling resistor are electrically connected switching tube, obtain inductance in switching tube shutdown
On peak point current enter proportional unit after keeping and carry out ratio and calculate to be formed and compare threshold value.
6. overvoltage crowbar according to claim 4, which is characterized in that the zero passage detection unit includes and inductance string
The current sampling resistor of connection and the detecting voltage unit of detecting current sampling resistor both end voltage, when current sampling resistor both ends electricity
Pressure drops to after zero point detecting voltage element output signal to timing unit or time switch.
7. overvoltage crowbar according to claim 4, which is characterized in that zero passage detection unit includes differential capacitance, micro-
Sub-resistance and negative voltage detecting unit, differential capacitance are connected on the intersection point of switching tube and inductance, differential resistance and differential capacitance
Series connection and differential resistance ground connection, negative voltage detecting unit detecting differential capacitance and the negative voltage at differential resistance tie point, negative electricity
Detecting unit is pressed to be electrically connected timing unit or time switch, once negative voltage detecting unit detects negative voltage, timing unit
Or time switch stops timing.
8. a kind of overvoltage crowbar characterized by comprising
It is sequentially connected in series load, inductance and switching tube in circuit；
Freewheeling diode is connected between load and inductance, forms discharge loop between inductance, freewheeling diode and load, when
When switching tube turns off, inductance is discharged by discharge loop；
Descending slope acquiring unit, obtains the descending slope of inductive current after switching tube shutdown, descending slope and output voltage at
Direct ratio；
Threshold setting unit, setting compare threshold value and are electrically connected judging unit；
Judging unit is electrically connected the descending slope acquiring unit and threshold setting unit, by characterization circuit output voltage
Descending slope and compare threshold value and be compared, according to the output voltage of comparison result decision circuitry whether over-voltage；
Protection location is electrically connected judging unit and switching tube, and when judging unit judges output voltage over-voltage, protection location is closed
Close switching tube；
It is constant or inductive current is discontinuous mode and inductance electricity in peak value that inductive current is critical continuous conduction mode and inductive current
When the peak value of stream is constant, descending slope acquiring unit includes zero passage detection unit and timing unit, and zero passage detection unit electrically connects
Connecing inductance, at the time of obtaining inductance electric current drops to zero point during discharge, timing unit is electrically connected zero passage detection unit,
Start timing in switching tube shutdown moment timing unit, timing terminates after inductive current drops to zero point, obtains inductive current
Fall time and will export fall time to judging unit, be compared with time threshold.
9. overvoltage crowbar according to claim 8, which is characterized in that the zero passage detection unit includes and inductance string
The current sampling resistor of connection and the detecting voltage unit of detecting current sampling resistor both end voltage, when current sampling resistor both ends electricity
Pressure drops to after zero point detecting voltage element output signal to timing unit or time switch.
10. overvoltage crowbar according to claim 8, which is characterized in that zero passage detection unit includes differential capacitance, micro-
Sub-resistance and negative voltage detecting unit, differential capacitance are connected on the intersection point of switching tube and inductance, differential resistance and differential capacitance
Series connection and differential resistance ground connection, negative voltage detecting unit detecting differential capacitance and the negative voltage at differential resistance tie point, negative electricity
Detecting unit is pressed to be electrically connected timing unit or time switch, once negative voltage detecting unit detects negative voltage, timing unit
Or time switch stops timing.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711120437.9A CN107834516B (en) | 2015-10-30 | 2015-10-30 | A kind of overvoltage crowbar for Switching Power Supply |
| CN201510728744.XA CN105244848B (en) | 2015-10-30 | 2015-10-30 | Over-voltage protection method and circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201510728744.XA CN105244848B (en) | 2015-10-30 | 2015-10-30 | Over-voltage protection method and circuit |
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| CN201711120437.9A Division CN107834516B (en) | 2015-10-30 | 2015-10-30 | A kind of overvoltage crowbar for Switching Power Supply |
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| CN105244848B true CN105244848B (en) | 2019-02-15 |
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| CN201711120437.9A Active CN107834516B (en) | 2015-10-30 | 2015-10-30 | A kind of overvoltage crowbar for Switching Power Supply |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11264902B2 (en) * | 2016-03-02 | 2022-03-01 | Analog Devices International Unlimited Company | Inductor current based mode control for buck-boost converters |
| CN107294066B (en) * | 2016-03-30 | 2019-08-13 | 比亚迪股份有限公司 | Guard method, device and the electric car of inverter |
| US10491207B2 (en) * | 2017-09-07 | 2019-11-26 | Infineon Technologies Austria Ag | Method of over current and over voltage protection of a power switch in combination with regulated DI/DT and DV/DT |
| CN108631271B (en) * | 2017-10-16 | 2020-01-07 | 西安矽力杰半导体技术有限公司 | Overcurrent protection control circuit |
| CN107947123A (en) * | 2017-10-24 | 2018-04-20 | 深圳市必易微电子有限公司 | ACDC protective circuit of switch power source and ACDC switching power units |
| CN109818328B (en) * | 2019-03-19 | 2020-09-11 | 浪潮商用机器有限公司 | Overvoltage protection circuit of switching power supply |
| CN112051883B (en) * | 2020-08-06 | 2022-11-29 | 苏州浪潮智能科技有限公司 | Chip control method for realizing quick current response |
| US11456677B2 (en) | 2020-12-10 | 2022-09-27 | Rolls-Royce Corporation | Power converter protection circuit |
| CN113381396B (en) * | 2021-07-13 | 2022-06-10 | 上海芯龙半导体技术股份有限公司南京分公司 | Circuit and power chip for input voltage abrupt change turn-off output |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101149945A (en) * | 2006-09-22 | 2008-03-26 | 富士通株式会社 | Clock extraction method for patterned medium, clock extraction circuit for patterned medium and patterned medium |
| CN201805600U (en) * | 2010-09-30 | 2011-04-20 | 杭州电子科技大学 | Primary-side constant-current control device of LED driver |
| CN102474964A (en) * | 2009-08-10 | 2012-05-23 | 欧司朗股份有限公司 | Method for controlling a voltage transformer for overvoltage protection, voltage transformer and operating device having a voltage transformer |
| CN102769386A (en) * | 2012-07-27 | 2012-11-07 | 成都芯源系统有限公司 | Switch converter and control circuit and control method thereof |
| CN104093254A (en) * | 2014-07-22 | 2014-10-08 | 矽力杰半导体技术(杭州)有限公司 | LED overvoltage detection circuit, drive circuit and LED illuminating system |
| CN104600677A (en) * | 2015-01-14 | 2015-05-06 | 常州格力博有限公司 | Short-circuit protection method for transistor in control circuit |
| CN205104896U (en) * | 2015-10-30 | 2016-03-23 | 杰华特微电子（杭州）有限公司 | Overvoltage protection circuit |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102340129B (en) * | 2010-07-23 | 2013-11-27 | 中国长城计算机深圳股份有限公司 | Switching power supply and overvoltage protection circuit thereof |
| CN204330872U (en) * | 2014-12-04 | 2015-05-13 | 杰华特微电子（杭州）有限公司 | The load voltage testing circuit of current zero-crossing point testing circuit and correspondence |
| CN104953829B (en) * | 2015-05-21 | 2018-05-04 | 西南交通大学 | A kind of certainly frequency peak current control method applied to BUCK converters |
-
2015
- 2015-10-30 CN CN201510728744.XA patent/CN105244848B/en active Active
- 2015-10-30 CN CN201711120437.9A patent/CN107834516B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101149945A (en) * | 2006-09-22 | 2008-03-26 | 富士通株式会社 | Clock extraction method for patterned medium, clock extraction circuit for patterned medium and patterned medium |
| CN102474964A (en) * | 2009-08-10 | 2012-05-23 | 欧司朗股份有限公司 | Method for controlling a voltage transformer for overvoltage protection, voltage transformer and operating device having a voltage transformer |
| CN201805600U (en) * | 2010-09-30 | 2011-04-20 | 杭州电子科技大学 | Primary-side constant-current control device of LED driver |
| CN102769386A (en) * | 2012-07-27 | 2012-11-07 | 成都芯源系统有限公司 | Switch converter and control circuit and control method thereof |
| CN104093254A (en) * | 2014-07-22 | 2014-10-08 | 矽力杰半导体技术(杭州)有限公司 | LED overvoltage detection circuit, drive circuit and LED illuminating system |
| CN104600677A (en) * | 2015-01-14 | 2015-05-06 | 常州格力博有限公司 | Short-circuit protection method for transistor in control circuit |
| CN205104896U (en) * | 2015-10-30 | 2016-03-23 | 杰华特微电子（杭州）有限公司 | Overvoltage protection circuit |
Also Published As
| Publication number | Publication date |
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| CN107834516A (en) | 2018-03-23 |
| CN107834516B (en) | 2019-04-02 |
| CN105244848A (en) | 2016-01-13 |
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Address after: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Patentee after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 424, building 1, 1500 Wenyi West Road, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province Patentee before: JOULWATT TECHNOLOGY (HANGZHOU) Co.,Ltd. |