CN209658895U - The control circuit and Switching Power Supply of Switching Power Supply - Google Patents
The control circuit and Switching Power Supply of Switching Power Supply Download PDFInfo
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- CN209658895U CN209658895U CN201920179571.4U CN201920179571U CN209658895U CN 209658895 U CN209658895 U CN 209658895U CN 201920179571 U CN201920179571 U CN 201920179571U CN 209658895 U CN209658895 U CN 209658895U
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Abstract
This application discloses a kind of control circuit of Switching Power Supply and Switching Power Supplies; control circuit includes: short-circuit protection circuit; detection signal is generated according to sampled voltage; wherein sampled voltage is provided by the sampling resistor sampled with the electric current for being used for switch tube in Switching Power Supply; if the rate of rise of sampled voltage is less than default slope value, detects signal and pulse signal is provided；And driving circuit, for providing switching signal, and the duty cycle according to pulse signal increase for the switching signal of control switch pipe, to increase the turn-off time of switching tube.Realize the effective protection under full voltage exchange input to switch power supply current sampling resistor short circuit.
Description
Technical field
The utility model relates to power electronic technique, control circuit and switch electricity more particularly, to Switching Power Supply
Source.
Background technique
With the increasingly increase of Switching Power Supply demand, production cost is reduced, increases application function and optimizes performance
Through the basic demand for becoming the power unit of general consumption electronic product.
Switching Power Supply is in production, test and uses etc. in links, there are several factors may cause it is certain in system
Device failure or short circuit, so that the normal work to Switching Power Supply causes security risk, therefore it is required that Switching Power Supply can be
Self-protection in the case where certain device exceptions in system, to further increase the safety of Switching Power Supply.For example, switching
In power supply application system, if sampling resistor damage or because in production process failure welding cause sampling resistor short-circuit,
The electric current for flowing through switching tube will be very big, beyond the upper safety limit value for switching tube current or magnetic core of transformer may be made serious
It is saturated, and then the element in Switching Power Supply is caused to be burned out, is i.e. " aircraft bombing " phenomenon, brought very to the production and use of Switching Power Supply
Big security risk.
Therefore, it is necessary to be improved to the prior art to improve the safety and reliability of Switching Power Supply.
Utility model content
In view of the above problems, the purpose of this utility model is to provide a kind of control circuit of Switching Power Supply and switch electricity
Source avoids making due to sampling resistor exception or short circuit to carry out short-circuit protection to Switching Power Supply under full voltage exchange input
It is damaged or fails at Switching Power Supply.
It is according to the present utility model in a first aspect, providing a kind of control circuit of Switching Power Supply, comprising: short-circuit protection electricity
Road generates detection signal according to sampled voltage, wherein the sampled voltage is by the electricity in the Switching Power Supply for switch tube
The sampling resistor that stream is sampled provides, if the rate of rise of the sampled voltage is less than default slope value, the detection letter
Number provide pulse signal；And driving circuit, believe for providing the switching signal for controlling the switching tube, and according to the pulse
Number increase the duty cycle of the switching signal of the switching tube, to increase the turn-off time of the switching tube.
Preferably, the driving circuit is in response to each pulse signal, in the control of each pulse signal
The lower duty cycle and turn-off time for increasing the switching tube.
Preferably, for the driving circuit in response to pulse signal described in one group, pulse signal described in every group includes successively going out
Existing multiple pulse signals, thus: at interval of a certain number of pulse signals, opened described in the driving circuit adjusting
OFF signal, so that the duty cycle and turn-off time of the switching tube are correspondingly increased.
Preferably, each pulse signal has rising edge and failing edge, and the driving circuit is in the pulse signal
Failing edge triggering under the switching signal become into inactive level from significant level so that the switching tube is become by state
For off state.
Preferably, the short-circuit protection circuit includes: comparison module, when the switching tube is in the conductive state, is compared
The sampled voltage and reference voltage, and output result signal, the consequential signal characterize the rate of rise of the sampled voltage
Whether it is less than the default slope value and the consequential signal is reset to low level when the switching tube is in an off state；
Timing module, when the conduction duration of the switching signal reaches detection time, the timing module provides sprocket pulse；
Logic module provides the detection signal according to the sprocket pulse and the consequential signal, when the sprocket pulse starts,
If the sampled voltage is less than the reference voltage, the detection signal provides the pulse signal, if the sampled voltage
More than or equal to the reference voltage, then the detection signal maintains high level, at the end of the sprocket pulse, the detection
Signal is reset to the high level.
Preferably, the short-circuit protection circuit further includes voltage generating module, for being provided according to the default slope value
The constant reference voltage.
Preferably, the comparison module is realized by comparator, and the normal phase input end of the comparator receives described with reference to electricity
Pressure, the inverting input terminal of the comparator receive the sampled voltage, and the output end of the comparator provides the consequential signal,
The sprocket pulse is high level pulse, when the conduction duration of switching tube reaches the detection time, the timing arteries and veins
Existing rising edge is gone out, failing edge occurs in the sprocket pulse after the switch periods, and the logic module is to the timing arteries and veins
Punching and the consequential signal carry out logical operation to generate the detection signal.
Preferably, the reference voltage is less than (ULmin*Rcs) * t/Lp, wherein ULmin is characterizing the Switching Power Supply just
The high direct voltage minimum value of input voltage when often working, Rcs characterize the resistance value of the sampling resistor, and Lp characterizes the primary side
The inductance of winding, t characterize the detection time.
Preferably, the control circuit further include: counter, the counter receive the detection signal, and right
The pulse signal is counted to obtain count value, and when the count value is equal to setting value, the counter is to the drive
Signal is effectively protected in dynamic circuit offer, so that the switching tube is turned off, the Switching Power Supply is restarted, and resets the meter
Numerical value.
Preferably, the driving circuit includes: oscillator, provides square-wave pulse, and the oscillator is believed according to the detection
Number adjust the pulsewidth of the square-wave pulse；And switch drive module, the switching signal is generated according to the square-wave pulse, often
The pulsewidth of a square-wave pulse corresponds to the duty cycle or inactive level time of the switching signal.
Preferably, the control circuit further include: feed circuit, for providing feedback letter according to the output electric current
Number, and/or for providing the feedback signal according to the sampled voltage or the output voltage, the driving circuit is according to institute
It states feedback signal and adjusts the switching signal；And power supply circuit, for providing supply voltage to institute according to the input current
State the feeder ear of driving circuit.
Preferably, less than the Switching Power Supply, the minimum of the sampled voltage becomes the default slope value in normal work
Rate.
Second aspect according to the present utility model provides a kind of Switching Power Supply, comprising: primary side winding and vice-side winding, institute
It states primary side winding and input current is generated according to input voltage, the vice-side winding generates output electric current according to the input current；
Switching tube and sampling resistor, the switching tube, the sampling resistor are connected with the primary side winding, and the sampling resistor is to flowing through
The electric current of the switching tube is sampled to obtain sampled voltage, and switching signal controls turn-on time and the shutdown of the switching tube
Time；Short-circuit protection circuit generates detection signal according to the sampled voltage, if the rate of rise of the sampled voltage is less than in advance
If slope value, then the detection signal provides pulse signal；And driving circuit, it is used to provide the described switching signal, and according to
The pulse signal increases the duty cycle of the switching signal, to increase the turn-off time of the switching tube.
Preferably, the driving circuit is in response to each pulse signal, in the control of each pulse signal
The lower duty cycle and turn-off time for increasing the switching tube.
Preferably, for the driving circuit in response to pulse signal described in one group, pulse signal described in every group includes successively going out
Existing multiple pulse signals, thus: at interval of a certain number of pulse signals, opened described in the driving circuit adjusting
OFF signal, so that the duty cycle and turn-off time of the switching tube are correspondingly increased.
Preferably, each pulse signal has rising edge and failing edge, and the driving circuit is in the pulse signal
Failing edge triggering under the switching signal become into inactive level from significant level so that the switching tube is become by state
For off state.
Preferably, the short-circuit protection circuit includes: comparison module, when the switching tube is in the conductive state, is compared
The sampled voltage and reference voltage, and output result signal, the consequential signal characterize the rate of rise of the sampled voltage
Whether it is less than the default slope value and the consequential signal is reset to low level when the switching tube is in an off state；
Timing module, when the conduction duration of the switching signal reaches detection time, the timing module provides sprocket pulse；
Logic module provides the detection signal according to the sprocket pulse and the consequential signal, when the sprocket pulse starts,
If the sampled voltage is less than the reference voltage, the detection signal provides the pulse signal, if the sampled voltage
More than or equal to the reference voltage, then the detection signal maintains high level, at the end of the sprocket pulse, the detection
Signal is reset to the high level.
Preferably, the short-circuit protection circuit further includes voltage generating module, for being provided according to the default slope value
The constant reference voltage.
Preferably, the comparison module is realized by comparator, and the normal phase input end of the comparator receives described with reference to electricity
Pressure, the inverting input terminal of the comparator receive the sampled voltage, and the output end of the comparator provides the consequential signal,
The sprocket pulse is high level pulse, when the conduction duration of switching tube reaches the detection time, the timing arteries and veins
Existing rising edge is gone out, failing edge occurs in the sprocket pulse after the switch periods, and the logic module is to the timing arteries and veins
Punching and the consequential signal carry out logical operation to generate the detection signal.
Preferably, the Switching Power Supply further include: counter, the counter receive the detection signal, and right
The pulse signal is counted to obtain count value, and when the count value is equal to setting value, the counter is to the drive
Signal is effectively protected in dynamic circuit offer, so that the switching tube is turned off, the Switching Power Supply is restarted, and resets the meter
Numerical value.
Preferably, the driving circuit includes: oscillator, provides square-wave pulse, and the oscillator is believed according to the detection
Number adjust the pulsewidth of the square-wave pulse；And switch drive module, the switching signal is generated according to the square-wave pulse, often
The pulsewidth of a square-wave pulse corresponds to the duty cycle or inactive level time of the switching signal.
Preferably, the Switching Power Supply further include: feed circuit, for providing feedback letter according to the output electric current
Number, and/or for providing the feedback signal according to the sampled voltage or the output voltage, the driving circuit is according to institute
It states feedback signal and adjusts the switching signal；Power supply circuit, for providing supply voltage to the drive according to the input current
The feeder ear of dynamic circuit.
Preferably, less than the Switching Power Supply, the minimum of the sampled voltage becomes the default slope value in normal work
Rate.
Preferably, the reference voltage is less than (ULmin*Rcs) * t/Lp, wherein ULmin is characterizing the Switching Power Supply just
The high direct voltage minimum value of input voltage when often working, Rcs characterize the resistance value of the sampling resistor, and Lp characterizes the primary side
The inductance of winding, t characterize the detection time.
The control circuit and Switching Power Supply of Switching Power Supply provided by the embodiment of the utility model are provided according to sampling resistor
The rate of rise of sampled voltage whether be less than default slope value abnormal to detect sampling resistor.When the rising of sampled voltage
When slope is less than default slope value, illustrate sampling resistor exception, then generate pulse signal to reduce the working frequency of Switching Power Supply,
To increase turn-off time of switching tube, and the adjusting of turn-off time is not limited by switch periods so that transformer primary side around
The electric current of group is sufficiently discharged, and avoids occurring the excessive phenomenon of primary side winding accumulation of electrical current in sampling resistor exception, thus
Sampling resistor short circuit or it is abnormal when can in the case where full voltage exchanges input protective switch power supply.
In preferred embodiment, when the rate of rise of sampled voltage is less than default slope value, it can also be opened in reduction
Reduce the turn-on time of switching tube while the working frequency in powered-down source, so that the accumulation of electrical current time of primary side winding shortens, into
The current accumulation of one step alleviation primary current.
In a preferred embodiment, it can also judge whether Switching Power Supply needs again by count to pulse signal
It is extensive then to determine that Switching Power Supply needs to carry out by restarting when the number that pulse signal occurs reaches preset upper limit for starting
It is multiple, so as to the protective switch power supply in the case where full voltage exchanges input condition, avoid sampling resistor there is abnormal or even short circuit and
Switching Power Supply is caused to be damaged.
In preferred embodiment, by the way that default slope value is rationally arranged, (default slope value is slightly less than switch electricity
The rate of rise of minimum input voltage down-sampling voltage when source works normally), to can avoid when sampling resistor works normally
The short-circuit protection mechanism of Switching Power Supply by false triggering, guarantee Switching Power Supply can in normal working voltage continuous work and
It is not interrupted.
Detailed description of the invention
By referring to the drawings to the description of the utility model embodiment, above-mentioned and other mesh of the utility model
, feature and advantage will be apparent from, in the accompanying drawings:
Fig. 1 shows the structural schematic diagram of the Switching Power Supply of the utility model first embodiment.
Fig. 2 shows the structural schematic diagrams of the short-circuit protection circuit of the utility model first embodiment.
Fig. 3 a shows the short-circuit protection circuit of the utility model first embodiment, and each signal waveform is shown under normal circumstances
It is intended to.Fig. 3 b shows the short-circuit protection circuit of the utility model first embodiment each signal waveform in short-circuit protection and shows
It is intended to.
Fig. 4 shows the structural schematic diagram of the driving circuit of the utility model first embodiment.
Fig. 5 shows waveform diagram of the input current within a duty cycle in the utility model first embodiment.
Fig. 6 shows the structural schematic diagram of the Switching Power Supply of the utility model second embodiment.
Fig. 7 shows the structural schematic diagram of the Switching Power Supply of the utility model 3rd embodiment.
Fig. 8 shows the waveform diagram for the input current that primary side winding provides in Switching Power Supply.
Fig. 9 shows the control method of the Switching Power Supply of the utility model fourth embodiment.
Specific embodiment
Hereinafter reference will be made to the drawings is more fully described the various embodiments of the utility model.In various figures, identical
Element is indicated using same or similar appended drawing reference.For the sake of clarity, the various pieces in attached drawing are not drawn to draw
System.Furthermore, it is possible to which certain well known parts are not shown.
Many specific details of the utility model, such as the structure of device, material, size, place are described hereinafter
Science and engineering skill or technology, to be more clearly understood that the utility model.But just as the skilled person will understand,
The utility model can not be realized according to these specific details.
The utility model can be presented in a variety of manners, some of them example explained below.
Fig. 1 shows the structural schematic diagram of the Switching Power Supply of the utility model first embodiment.
As shown in Figure 1, the Switching Power Supply 100 includes rectifier bridge 110, control circuit 1000, transformer, switching tube M1, adopts
Sample resistance Rcs, sustained diode 0, input capacitance Cin and output capacitance Cout.Wherein, rectifier bridge 110 is defeated for that will exchange
Enter signal and be converted to input voltage vin, input capacitance Cin is for being stablized and being filtered to input voltage vin；Transformer includes
Primary side winding Lp and vice-side winding Ls, primary side winding are connected and with switching tube M1 and sampling resistor Rcs according to input voltage vin
Input current Iin is generated, vice-side winding Ls connects with sustained diode 0, and vice-side winding Ls generates defeated according to input current Iin
Electric current out, output capacitance Cout are stablized and are filtered to output voltage Vout；Sampling resistor Rcs is to the electricity for flowing through switching tube M1
Stream is sampled to obtain sampled voltage Vcs, which for example for the working condition of detection switch power supply or realizes anti-
Feedback control.
As a kind of specific embodiment, as shown in Figure 1, switching tube M1 is connected on primary side winding Lp and sampling resistor Rcs
Between, the first end that sampling resistor Rcs is connected with the pipe M1 that opens the light provides sampled voltage Vcs, another termination ground reference.It needs
Illustrate, Fig. 1 illustrates only a kind of structure of Switching Power Supply, and the Switching Power Supply of the utility model embodiment can also be by switching
The elements such as pipe M1, transformer, sustained diode 0 are constituted according to other connection types, enable sampling resistor Rcs according to stream
Electric current through switching tube M1 provides sampled voltage Vcs.
Control circuit 1000 is used to provide switching signal sw according to sampled voltage Vcs, and allows in sampled voltage Vcs exception
Switching Power Supply enters short-circuit modes of warning.The control terminal of switching tube M1 receives switching signal sw, so that switching signal sw can be controlled
The turn-on time ton and turn-off time toff of switching tube M1 processed.
Specifically, control circuit 1000 includes driving circuit 130 and short-circuit protection circuit 120.Short-circuit protection circuit 120 is used
In detection switch power supply whether work abnormality (such as sampling resistor Rcs there is abnormal or even short circuit and cause primary side around
Electric current excessive accumulation in group Lp), and detection signal Vsen is generated according to testing result；Driving circuit 130 is in detection signal
Switching signal sw to switching tube M1 is provided under the control of Vsen, thus when detecting signal Vsen characterization normal condition, driving electricity
130 driving switch power supply of road continues to work normally, and when detecting signal Vsen characterization abnormality, driving circuit 130 drives
Switching Power Supply enters short-circuit modes of warning with protective switch power supply.
In the present embodiment, short-circuit protection circuit 120 judges that Switching Power Supply is according to the rate of rise of sampled voltage Vcs
No work is in abnormality.When the rate of rise of sampled voltage Vcs is less than default slope value, then detecting signal Vsen will provide
Pulse signal, driving circuit 130 increase the duty cycle of switching signal sw when receiving pulse signal, i.e. reduction Switching Power Supply
Working frequency, thus not by work normally the period limited under increase switching tube M1 turn-off time toff so that primary side
The electric current accumulated on winding Lp interior when off can sufficiently be discharged.
In a preferred embodiment, driving circuit 130 can also reduce the conducting of switching tube M1 when receiving pulse signal
Time ton.In a particularly preferred embodiment, driving circuit 130 can disconnect in triggering ShiShimonoseki of the failing edge of pulse signal
Pipe M1 is closed, the turn-on time of switching tube M1 is reduced to fixed value at this time, such as is reduced to detection time tj.
It should be noted that in some embodiments, switch letter can be increased under the control of each pulse signal
Number duty cycle, i.e., driving circuit 130 is in response to each pulse signal.And in some alternative embodiments, electric current is in original
The accumulation of side winding is limited, therefore can also be at interval of at least one pulse signal ability regulating switch signal, so that work week
Phase and the turn-off time of switching tube are correspondingly increased, that is to say, that the driving circuit in response to pulse signal described in one group,
Pulse signal described in every group includes the multiple pulse signals successively occurred, thus: at interval of a certain number of pulses
Signal, the driving circuit adjust the switching signal so that the duty cycle and turn-off time of the switching tube correspondingly by
Increase.
Fig. 2 shows the structural schematic diagrams of the short-circuit protection circuit of the utility model first embodiment.Fig. 3 a shows practical
The waveform diagram of the short-circuit protection circuit of novel first embodiment each signal under normal circumstances.It is practical new that Fig. 3 b shows this
The waveform diagram of the short-circuit protection circuit of type first embodiment each signal in short-circuit protection.
As shown in Fig. 2, short-circuit protection circuit 120 include comparison module 121, timing module 122, logic module 123 and
Voltage generating module 124.
Comparison module 121 is for comparing sampled voltage Vcs and reference voltage Vref, and output result signal Vcomp, the knot
Whether the rate of rise of fruit signal Vcomp characterization sampled voltage Vcs is less than default slope value.
Timing module 122 is for providing sprocket pulse Vj.Timing in the initial time of switch periods to the switch periods
There is fixed detection time between the rising edge of pulse.
Voltage generating module 124 is for providing reference voltage Vref.Reference voltage Vref can be fixed voltage, can also be with
It is that the ramp voltage for following input voltage to change can make reference voltage Vref by the reasonable setting to reference voltage Vref
Whether it is less than default slope value with the rate of rise of the comparison result characterization sampled voltage Vcs of sampled voltage Vcs.
Logic module 123 is used to provide detection signal Vsen according to sprocket pulse Vj and consequential signal Vcomp.When detecting
In, without the comparison between sampled voltage and reference voltage, detects signal and be in original state (for example, high level).When
When sprocket pulse Vj rising edge starts, if sampled voltage Vcs is less than reference voltage Vref, illustrate the rising of sampled voltage Vcs
Slope is less than default slope value (climbing speed for flowing through the electric current of switching tube M1 does not reach reasonable value), and Switching Power Supply may
There is unusual condition, need to enter short-circuit modes of warning, detects signal Vsen at this time and pulse signal is provided；Conversely, working as timing
When pulse Vj rising edge starts, if sampled voltage Vcs is more than or equal to reference voltage Vref, illustrate that the rising of sampled voltage Vcs is oblique
Rate is more than or equal to default slope value (rate of rise for flowing through the electric current of switching tube M1 has reached reasonable value), the temporary nothing of Switching Power Supply
Unusual condition does not need to enter short-circuit modes of warning, detects signal Vsen at this time and maintain initial high level.Further,
Detection signal Vsen can be reset to high level after switching tube shutdown.
As a kind of specific embodiment, as shown in Fig. 2, Fig. 3 a and Fig. 3 b, comparison module 121 is realized by comparator, than
Normal phase input end compared with device receives reference voltage Vref, and the inverting input terminal of comparator receives sampled voltage Vcs, comparator it is defeated
Outlet provides consequential signal Vcomp, and sprocket pulse Vj is square-wave pulse, and logic module 123 is to sprocket pulse Vj and consequential signal
Vcomp carries out logical operation (for example, NAND operation) and detects signal Vsen to generate, to provide in Switching Power Supply exception
Pulse signal.
When Switching Power Supply works normally, input voltage is equally likely to the smaller value within the scope of normal input voltage Vin, this
When sampled voltage Vcs climbing speed it is very slow, it is therefore desirable to default slope value is rationally set to prevent the mistake of short-circuit modes of warning
Triggering.Specifically, (input is electric when i.e. Switching Power Supply works normally for the minimum amount of voltage that after being stablized according to input voltage vin
The minimum value of pressure) calculate default slope value so that default slope value be less than or equal to Switching Power Supply provide in normal work it is defeated
Enter the minimum rate of change of electric current.Based on this, reference signal Vref for example meets:
Wherein, ULmin indicates the minimum value of input direct-current high pressure when Switching Power Supply works normally, and Rcs indicates sampling resistor
Resistance value, Lp characterize primary side winding inductance, tj characterize detection time.
On the other hand, other than avoiding the problem that false triggering, it is also noted that Switching Power Supply after short circuit occurs for sampling resistor
Not the problem of short-circuit protection is not triggered when starting up.Therefore reference voltage is set smaller than Switching Power Supply in soft start mistake
First current limit step value in journey.
In addition, in order to prevent sampling resistor Rcs short circuit when primary side winding on electric current it is excessive and cause in Switching Power Supply
Element is burned out, and within the first job period after Switching Power Supply enters short-circuit modes of warning, switching tube is open-minded at this time
Time is equal to detection time, and the current peak Ipk in primary side winding should will meet:
Wherein, Bm characterizes the peakflux density of transformer, and Np characterizes transformer primary side the number of turns, and Ae characterizes magnetic core of transformer
Effective sectional area, UL indicate input direct-current high pressure (normally due under high pressure electric current rise it is very fast, therefore herein calculate Ipk with
Should be solved when Bm with maximum input voltage in system worked well voltage range), Lp characterizes the inductance of primary side winding, t
The service time of short-circuit protection is characterized, Iv indicates initial current.It should be noted that the boundary value of magnetic flux density is usually
0.35, however those skilled in the art also can be set according to actual needs other boundary values.
Fig. 4 shows the structural schematic diagram of the driving circuit of the utility model first embodiment.Fig. 5 shows the utility model
Waveform diagram of the input current within a duty cycle in one embodiment.
As shown in figure 4, driving circuit 130 includes switch drive module 131 and oscillator 132.Switch drive module 131 is used
In generation switching signal sw；Oscillator 132 is for providing square-wave pulse to switch drive module 131, each square-wave pulse
Corresponding to the duty cycle or inactive level time of the switching signal, so that oscillator 132 being capable of regulating switch drive module
The duty cycle or inactive level time of the switching signal sw of 131 outputs.Specifically, when oscillator 132 receives pulse signal
When, oscillator 132 will increase the pulsewidth of square-wave pulse, so that switch drive module 131 reduces the working frequency of switching tube, thus
Increase the turn-off time toff of switching tube, to allow in primary side winding the electric current accumulated sufficiently to be discharged.
When having continuously generated multiple pulse signals in Switching Power Supply, in order to ensure serious product will not occur for primary current
It is tired, need reasonably to be arranged the turn-off time toff of switching tube so that in each duty cycle in turn on process input current
Increment Δ I1 and the reduction amount Δ I2 of input current in turn off process it is close or identical (as shown in Figure 5), that is, need to meet:
Wherein, ULmax characterizes the maximum DC voltage value of input voltage vin under normal circumstances, and ton characterizes switching tube M1
Turn-on time, toff characterizes the turn-off time of switching tube M1, and n characterizes the turn ratio between primary side winding and vice-side winding, Vs
Characterize the voltage at vice-side winding both ends.As can be seen that when Switching Power Supply is loaded after sampling resistor short circuit using high drive,
Vs minimum (such as can be 0.5V with value), the turn-off time toff longest needed at this time.
Fig. 6 shows the structural schematic diagram of the Switching Power Supply of the utility model second embodiment.
As shown in fig. 6, the Switching Power Supply of the Switching Power Supply 200 of the utility model second embodiment and above-mentioned first embodiment
100 is essentially identical, the difference is that: Switching Power Supply 200 can also control driving circuit from short according to the quantity of pulse signal
Road modes of warning enters short circuit protection mode, so that Switching Power Supply is restarted or directly turned off, to prevent the element in Switching Power Supply
Excessive electric current is born in sampling resistor short circuit or exception and is burned out.
Specifically, on the basis of above-mentioned first embodiment, as shown in fig. 6, the control circuit 1000 of Switching Power Supply 200 is also
Including counter 140, detection signal Vsen is received, so as to be counted pulse signal to obtain count value.
When count value is equal to setting value, signal Vrst is effectively protected to the offer of driving circuit 130 in counter 140, is driven
Dynamic circuit 130 will enter short circuit protection mode.Under short circuit protection mode, switching tube M1 is turned off, and entire Switching Power Supply can
To be closed/restart, and count value will be reset to 0, to prepare after Switching Power Supply restarting again to pulse signal
It is counted.
In some embodiments, the count value that counter obtains can be used for control driving circuit, so that driving circuit
It is not responsive to each pulse signal, and only in response to the pulse signal being spaced after at least one pulse signal.
Fig. 7 shows the structural schematic diagram of the Switching Power Supply of the utility model 3rd embodiment.
As shown in fig. 7, the Switching Power Supply 300 of the utility model 3rd embodiment and above-mentioned first embodiment and second are implemented
The Switching Power Supply of example is essentially identical, wherein control circuit 1000 can be with the control circuit of above-mentioned first embodiment or above-mentioned the
The control circuit of two embodiments is identical.The difference is that Switching Power Supply 300 further includes feed circuit 360 and/or power supply circuit
350。
Feed circuit 360 is used to (or be adopted according to sampled voltage Vcs and/or the output voltage Vout generated by output electric current
Sample voltage) feedback signal Vfb is provided, the Vfb regulating switch signal sw based on the feedback signal of the driving circuit in control circuit 1000,
To carry out feedback control to Switching Power Supply.
Power supply circuit 350 is used to provide supply voltage Vcc to control circuit 1000, supply voltage according to input current Iin
Vcc can be used as the supply voltage of driving circuit and short-circuit protection circuit in control circuit.
Fig. 8 shows the waveform diagram for the input current that primary side winding provides in Switching Power Supply.
As shown in Fig. 1, Fig. 6, Fig. 7 and Fig. 8, (such as corresponding time period t 0-t1), driving when Switching Power Supply works normally
The work of circuit 130 is in normal mode of operation, switching tube M1 turn-on and turn-off under the action of switching signal sw, to guarantee output electricity
Press Vout stabilization and duty cycle T it is constant.When switching signal sw is effective, switching tube M1 conducting, primary side winding Lp is provided
Input current Iin be gradually increased at any time, at its, the rate of rise of input current Iin is more than or equal to default slope
Value；When switching signal sw is invalid, switching tube M1 shutdown, input current Iin is gradually reduced at any time.
When Switching Power Supply work in abnormality (such as corresponding time period t 1-t2), for example, sampling resistor Rs occur it is short
Road, if, since the voltage value of sampled voltage Vcs can not detect, switching tube M1 will be with maximum without short-circuit protection circuit 120
Duty cycle, the turn-on time of switching tube M1 is very long at this time and is persistently greater than the turn-off time, this will cause transformer primary side electricity
It flows persistent accumulation and cannot sufficiently be discharged in each duty cycle T.When input current makes the magnetic core of primary side winding serious
When saturation, it will lead to Switching Power Supply and be burned out under the action of high current.
And in embodiments herein, when Switching Power Supply work in abnormality (such as corresponding time period t 2-t3),
Such as short circuit occurs for sampling resistor Rs, short-circuit protection circuit 120 can judge the climbing speed of sampled voltage Vcs, if
The climbing speed of sampled voltage Vcs is less than reasonably default slope value, then generates pulse signal, so that driving circuit 130 enters
Short-circuit modes of warning.Under short-circuit modes of warning, the duty cycle T of switching tube M1 is increased the turn-off time so that switching tube M1
Toff increases, to directly increase the time of primary side winding release current.
In a preferred embodiment, the turn-on time of switching tube M1 can also be reduced simultaneously (such as be decreased to one it is solid
Definite value) so that the time of primary side winding Accumulation current can also shorten, further prevent the input current mistake in primary side winding
Greatly.
In a preferred embodiment, as shown in figure 8, when the number of pulse signal reaches setting value (such as 3 moment it
Afterwards), driving circuit 130 can be with on-off switching tube M1 to close/reset switch power supply, so that the input current in primary side winding is held
Continuous decline.
Fig. 9 shows the short-circuit protection method of the Switching Power Supply of the utility model fourth embodiment.
The Switching Power Supply of the present embodiment can be the Switching Power Supply in the various embodiments described above, comprising: primary side winding and secondary side
Winding, primary side winding generate input current according to input voltage, and vice-side winding generates output electric current according to the input current；It opens
It closes pipe and sampling resistor, switching tube, sampling resistor is connected with primary side winding, sampling resistor adopts the electric current for flowing through switching tube
Sample is to obtain sampled voltage, the turn-on time of switching signal control switch pipe and turn-off time.
As shown in figure 9, the short-circuit protection method includes the following steps S110 to S140.Wherein step S120 and step S140
It can be omitted.
Step S110 generates detection signal according to sampled voltage, if the rate of rise of sampled voltage is less than default slope value,
It then detects signal and pulse signal is provided.The pulse signal is for making Switching Power Supply enter short-circuit modes of warning.Pulse signal has
Rising edge and failing edge.
As one embodiment, can be by comparing the rate of rise of sampled voltage and reference voltage detection sampled voltage
It is no to be less than preset value.When the conduction duration of switching signal reaches detection time, if sampled voltage is less than reference voltage,
Pulse signal is provided.
The specific steps for providing pulse signal include: to open when the conduction duration of switching signal reaches detection time
Beginning, (for example there is rising edge to offer sprocket pulse in sprocket pulse at this time, resets to low electricity again after the switch periods
It is flat), if detecting at this time, sampled voltage is less than reference voltage, provides the failing edge of pulse signal；When switching tube is turned off
It can terminate sprocket pulse, and the rising edge of pulse signal is provided or will test signal and is reset to original levels.
As preferred embodiment, detection time can be set according to the magnetic flux density of primary side winding, with prevent primary side around
Group reaches saturation, can also provide reference voltage according to detection time, reference voltage can be constant voltage or ramp voltage.For
Guarantee that short-circuit modes of warning will not in normal work (when input voltage is smaller) by false triggering, default slope value is slightly less than out
Powered-down source work normally when minimum input voltage under input current change rate.
Whether step S120, the number for judging that pulse signal occurs reach setting value.If so then execute step S140；If
It is no, then follow the steps S130.
In step s 130, increase the duty cycle of switching signal, according to pulse signal to increase the pass of the switching tube
The disconnected time.
As one embodiment, characterization switching signal duty cycle/turn-off time square-wave pulse, Mei Gefang can be provided
The pulsewidth of wave impulse is for example corresponding to the duty cycle of switching signal or inactive level time, later according to detection Signal Regulation side
The pulsewidth of wave impulse, so that duty cycle and turn-off time of the switching tube under short-circuit modes of warning are lengthened out.
In a preferred embodiment, step S130 further include: reduce the turn-on time of switching tube according to pulse signal, thus
Further alleviate the accumulation of electrical current in primary side winding.Specifically, can under the triggering of the failing edge of pulse signal, switching tube by
On state becomes an OFF state, thus before the normally time terminates, on-off switching tube in advance.
In step S140, when the number that pulse signal occurs reaches setting value, on-off switching tube makes Switching Power Supply
Enter short circuit protection mode from short-circuit modes of warning.Specific steps include: to be counted pulse signal to obtain count value；When
When count value is equal to setting value, on-off switching tube, reset switch power supply, and reset count value.
In conclusion the control circuit and Switching Power Supply of Switching Power Supply provided by the embodiment of the utility model are according to sampling
Whether whether the rate of rise for the sampled voltage that resistance provides is less than default slope value abnormal to detect sampling resistor.When sampling electricity
When the rate of rise of pressure is less than default slope value, illustrates sampling resistor exception, then generate pulse signal to reduce Switching Power Supply
Working frequency, so as to increase the turn-off time of switching tube, and the adjusting of turn-off time is not limited by switch periods, so that
The electric current of transformer primary winding is sufficiently discharged, and avoids primary side winding accumulation of electrical current occur in sampling resistor exception excessive
The phenomenon that, thus the protective switch power supply in sampling resistor short circuit or exception.
In preferred embodiment, when the rate of rise of sampled voltage is less than default slope value, it can also be opened in reduction
Reduce the turn-on time of switching tube while the working frequency in powered-down source, so that the accumulation of electrical current time of primary side winding shortens, into
The current accumulation of one step alleviation primary current.
In a preferred embodiment, it can also judge whether Switching Power Supply needs again by count to pulse signal
It is extensive then to determine that Switching Power Supply needs to carry out by restarting when the number that pulse signal occurs reaches preset upper limit for starting
It is multiple, so as to the protective switch power supply in the case where full voltage exchanges input condition, avoid sampling resistor there is abnormal or even short circuit and
Switching Power Supply is caused to be damaged.
In preferred embodiment, by the way that default slope value is rationally arranged, (default slope value is slightly less than switch electricity
The rate of rise of minimum input voltage down-sampling voltage when source works normally), to can avoid when sampling resistor works normally
The short-circuit protection mechanism of Switching Power Supply by false triggering, guarantee Switching Power Supply can under normal circumstances continuous work without being beaten
It is disconnected.
It is for example above according to the embodiments of the present invention, these embodiments details all there is no detailed descriptionthe, also not
Limit the specific embodiment that the utility model is only.Obviously, as described above, can make many modifications and variations.This explanation
These embodiments are chosen and specifically described to book, is in order to preferably explain the principles of the present invention and practical application, to make
Skilled artisan can be used using the utility model and modification on the basis of the utility model well.This
The protection scope of utility model should be subject to the range that the utility model claims are defined.
Claims (24)
1. a kind of control circuit of Switching Power Supply characterized by comprising
Short-circuit protection circuit generates detection signal according to sampled voltage, wherein the sampled voltage in the Switching Power Supply by using
It is provided in the sampling resistor that the electric current of switch tube is sampled, if the rate of rise of the sampled voltage is less than default slope
Value, then the detection signal provides pulse signal；And
Driving circuit increases the switch for providing the switching signal for controlling the switching tube, and according to the pulse signal
The duty cycle of the switching signal of pipe, to increase the turn-off time of the switching tube.
2. control circuit according to claim 1, which is characterized in that the driving circuit is believed in response to each pulse
Number, to increase the duty cycle and turn-off time of the switching tube under the control of each pulse signal.
3. control circuit according to claim 1, which is characterized in that the driving circuit is believed in response to pulse described in one group
Number, pulse signal described in every group includes the multiple pulse signals successively occurred, thus:
At interval of a certain number of pulse signals, the driving circuit adjusts the switching signal, so that the switching tube
Duty cycle and the turn-off time be correspondingly increased.
4. control circuit according to claim 1, which is characterized in that each pulse signal has rising edge and decline
The switching signal is become invalid electricity from significant level under the failing edge triggering of the pulse signal by edge, the driving circuit
It is flat, so that the switching tube is become an OFF state by state.
5. control circuit according to claim 1, which is characterized in that the short-circuit protection circuit includes:
Comparison module, when the switching tube is in the conductive state, the sampled voltage and reference voltage, and export result
Signal, whether the rate of rise that the consequential signal characterizes the sampled voltage is less than the default slope value, when the switch
When managing in an off state, the consequential signal is reset to low level；
Timing module, when the conduction duration of the switching signal reaches detection time, the timing module provides timing
Pulse；
Logic module provides the detection signal according to the sprocket pulse and the consequential signal,
When the sprocket pulse starts, if the sampled voltage is less than the reference voltage, the detection signal provides institute
Pulse signal is stated, if the sampled voltage is more than or equal to the reference voltage, the detection signal maintains high level,
At the end of the sprocket pulse, the detection signal is reset to the high level.
6. control circuit according to claim 5, which is characterized in that the short-circuit protection circuit further includes that voltage generates mould
Block, for providing the constant reference voltage according to the default slope value.
7. control circuit according to claim 5, which is characterized in that the comparison module realized by comparator, the ratio
The reference voltage is received compared with the normal phase input end of device, the inverting input terminal of the comparator receives the sampled voltage, described
The output end of comparator provides the consequential signal,
The sprocket pulse is high level pulse, when the conduction duration of switching tube reaches the detection time, the meter
Clock pulse goes out existing rising edge, and failing edge occurs in the sprocket pulse after the switch periods,
The logic module carries out logical operation to the sprocket pulse and the consequential signal to generate the detection signal.
8. control circuit according to claim 5, which is characterized in that the reference voltage is less than (ULmin*Rcs) * t/
Lp,
Wherein, ULmin characterize the Switching Power Supply work normally when input voltage high direct voltage minimum value, Rcs characterization described in
The resistance value of sampling resistor, Lp characterize the inductance of primary side winding, and t characterizes the detection time.
9. control circuit according to claim 1, which is characterized in that further include:
Counter, the counter receives the detection signal, and is counted the pulse signal to obtain count value,
When the count value is equal to setting value, signal is effectively protected to driving circuit offer in the counter, so that
The switching tube is turned off, the Switching Power Supply is restarted, and resets the count value.
10. control circuit according to claim 1, which is characterized in that the driving circuit includes:
Oscillator provides square-wave pulse, the pulsewidth of oscillator square-wave pulse according to the detection Signal Regulation；And
Switch drive module generates the switching signal according to the square-wave pulse, and the pulsewidth of each square-wave pulse is corresponding
In the duty cycle or inactive level time of the switching signal.
11. control circuit according to claim 10, which is characterized in that further include:
Feed circuit is used to provide feedback signal according to output electric current, and/or for according to the sampled voltage or output voltage
The feedback signal is provided, the driving circuit adjusts the switching signal according to the feedback signal；And
Power supply circuit, for providing the feeder ear of supply voltage to the driving circuit according to input current.
12. control circuit according to claim 1, which is characterized in that the default slope value is less than the Switching Power Supply
The minimum rate of change of the sampled voltage in normal work.
13. a kind of Switching Power Supply characterized by comprising
Primary side winding and vice-side winding, the primary side winding according to input voltage generate input current, the vice-side winding according to
The input current generates output electric current；
Switching tube and sampling resistor, the switching tube, the sampling resistor are connected with the primary side winding, the sampling resistor pair
The electric current for flowing through the switching tube is sampled to obtain sampled voltage, switching signal control the switching tube turn-on time and
Turn-off time；
Short-circuit protection circuit generates detection signal according to the sampled voltage, if the rate of rise of the sampled voltage is less than in advance
If slope value, then the detection signal provides pulse signal；And
Driving circuit is used to provide the described switching signal, and increases the work week of the switching signal according to the pulse signal
Phase, to increase the turn-off time of the switching tube.
14. Switching Power Supply according to claim 13, which is characterized in that the driving circuit is in response to each pulse
Signal, to increase the duty cycle and turn-off time of the switching tube under the control of each pulse signal.
15. Switching Power Supply according to claim 13, which is characterized in that the driving circuit is in response to pulse described in one group
Signal, pulse signal described in every group include the multiple pulse signals successively occurred, thus:
At interval of a certain number of pulse signals, the driving circuit adjusts the switching signal, so that the switching tube
Duty cycle and the turn-off time be correspondingly increased.
16. Switching Power Supply according to claim 13, which is characterized in that each pulse signal has rising edge under
Edge drops, and the switching signal is become invalid from significant level under the failing edge triggering of the pulse signal by the driving circuit
Level, so that the switching tube is become an OFF state by state.
17. Switching Power Supply according to claim 13, which is characterized in that the short-circuit protection circuit includes:
Comparison module, when the switching tube is in the conductive state, the sampled voltage and reference voltage, and export result
Signal, whether the rate of rise that the consequential signal characterizes the sampled voltage is less than the default slope value, when the switch
When managing in an off state, the consequential signal is reset to low level；
Timing module, when the conduction duration of the switching signal reaches detection time, the timing module provides timing
Pulse；
Logic module provides the detection signal according to the sprocket pulse and the consequential signal,
When the sprocket pulse starts, if the sampled voltage is less than the reference voltage, the detection signal provides institute
Pulse signal is stated, if the sampled voltage is more than or equal to the reference voltage, the detection signal maintains high level,
At the end of the sprocket pulse, the detection signal is reset to the high level.
18. Switching Power Supply according to claim 17, which is characterized in that the short-circuit protection circuit further includes that voltage generates
Module, for providing the constant reference voltage according to the default slope value.
19. Switching Power Supply according to claim 17, which is characterized in that the comparison module is realized by comparator, described
The normal phase input end of comparator receives the reference voltage, and the inverting input terminal of the comparator receives the sampled voltage, institute
The output end for stating comparator provides the consequential signal,
The sprocket pulse is high level pulse, when the conduction duration of switching tube reaches the detection time, the meter
Clock pulse goes out existing rising edge, and failing edge occurs in the sprocket pulse after the switch periods,
The logic module carries out logical operation to the sprocket pulse and the consequential signal to generate the detection signal.
20. Switching Power Supply according to claim 13, which is characterized in that further include:
Counter, the counter receives the detection signal, and is counted the pulse signal to obtain count value,
When the count value is equal to setting value, signal is effectively protected to driving circuit offer in the counter, so that
The switching tube is turned off, the Switching Power Supply is restarted, and resets the count value.
21. Switching Power Supply according to claim 13, which is characterized in that the driving circuit includes:
Oscillator provides square-wave pulse, the pulsewidth of oscillator square-wave pulse according to the detection Signal Regulation；And
Switch drive module generates the switching signal according to the square-wave pulse, and the pulsewidth of each square-wave pulse is corresponding
In the duty cycle or inactive level time of the switching signal.
22. Switching Power Supply according to claim 21, which is characterized in that further include:
Feed circuit is used to provide feedback signal according to the output electric current, and/or for according to the sampled voltage or output
Voltage provides the feedback signal, and the driving circuit adjusts the switching signal according to the feedback signal；
Power supply circuit, for providing the feeder ear of supply voltage to the driving circuit according to the input current.
23. Switching Power Supply according to claim 13, which is characterized in that the default slope value is less than the Switching Power Supply
The minimum rate of change of the sampled voltage in normal work.
24. Switching Power Supply according to claim 17, which is characterized in that the reference voltage is less than (ULmin*Rcs) * t/
Lp,
Wherein, ULmin characterizes the high direct voltage minimum value of the input voltage when Switching Power Supply works normally, Rcs characterization
The resistance value of the sampling resistor, Lp characterize the inductance of the primary side winding, and t characterizes the detection time.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920179571.4U CN209658895U (en) | 2019-01-31 | 2019-01-31 | The control circuit and Switching Power Supply of Switching Power Supply |
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| CN201920179571.4U CN209658895U (en) | 2019-01-31 | 2019-01-31 | The control circuit and Switching Power Supply of Switching Power Supply |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109638785A (en) * | 2019-01-31 | 2019-04-16 | 杭州士兰微电子股份有限公司 | Control circuit, Switching Power Supply and its control method of Switching Power Supply |
| CN117317977A (en) * | 2023-11-02 | 2023-12-29 | 深圳市德兰明海新能源股份有限公司 | Switching tube driving protection circuit and energy storage power supply |
-
2019
- 2019-01-31 CN CN201920179571.4U patent/CN209658895U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109638785A (en) * | 2019-01-31 | 2019-04-16 | 杭州士兰微电子股份有限公司 | Control circuit, Switching Power Supply and its control method of Switching Power Supply |
| CN117317977A (en) * | 2023-11-02 | 2023-12-29 | 深圳市德兰明海新能源股份有限公司 | Switching tube driving protection circuit and energy storage power supply |
| CN117317977B (en) * | 2023-11-02 | 2024-03-15 | 深圳市德兰明海新能源股份有限公司 | Switching tube driving protection circuit and energy storage power supply |
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