CN108365739A - A kind of control method of switching circuit, control circuit and switching power circuit - Google Patents
A kind of control method of switching circuit, control circuit and switching power circuit Download PDFInfo
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- CN108365739A CN108365739A CN201810208098.8A CN201810208098A CN108365739A CN 108365739 A CN108365739 A CN 108365739A CN 201810208098 A CN201810208098 A CN 201810208098A CN 108365739 A CN108365739 A CN 108365739A
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0009—Devices or circuits for detecting current in a converter
Abstract
The invention discloses a kind of control method of switching circuit, control circuit and switching power circuits.The switching circuit includes main power tube, rectifying tube and inductance, and the control method includes：The main power tube conducting, the rectifying tube shutdown, start timing, when inductance sample rate current or main power tube sample rate current reach first threshold, timing time is used as at the first time, and reclocking, after the second time, if the inductance sample rate current or the main power tube sample rate current are more than second threshold, the switching circuit is in critical conduction mode, and otherwise the switching circuit is in and is continuously turned on state.Overvoltage protection false triggering can be prevented in switching circuit inductive current zero passage error detection using the present invention, improve system reliability.
Description
Technical field
The present invention relates to power electronics fields, and in particular to a kind of control method of switching circuit, control circuit and
Switching power circuit.
Background technology
In the Switching Power Supply of critical conduction mode work, main switch shutdown, rectifying tube conducting, inductive current decline,
When Switching Power Supply detects that inductive current drops to 0, then main switch is connected, and rectifying tube shutdown, inductive current rises.Existing skill
In art, feedback voltage or main switch grid voltage are exported by detection to judge whether inductive current drops to 0.But
When detecting, due to external disturbance, inductive current has not degraded to 0 Switching Power Supply, just takes for dropping to 0, causes to enter company
Continuous conduction mode, and it is easy false triggering overvoltage protection.
To judge being illustrated for whether inductive current drops to 0 by detecting main switch grid voltage.It please join
It examines shown in Fig. 1, is Buck reduction voltage circuits.It is glitch-free ideally, when main switch M00 conducting, input terminal is to load
D01 powers, at this time inductive current iLRise；Work as iLWhen rising to IREF, main switch M00 shutdowns, inductance L00 releases energy, this
When inductive current iLIt is begun to decline from IREF, until inductive current iLIt is down to 0, since diode D00 is unable to reverse-conducting, electric current
Inductance is flowed to by the gate-drain parasitic capacitances C01 to ground resistance R00 and switching tube M00, the grid of M00 will appear negative pressure at this time,
When detecting the negative pressure of grid, critical conduction mode control is realized in switching tube M00 conductings.It is dry by outside in practical applications
Disturb, for example, power grid influence so that the drain terminal of M00, which can be disturbed, is then coupled to grid end, be easy in this way main switch M00 close
Disconnected mistiming detects the negative pressure of grid end, and M00 is caused to mislead.Refering to what is shown in Fig. 2, in A ' this moment, error detection inductive current
Zero passage, main switch conducting, into continuous conduction mode.When output voltage is got higher, the turn-off time of main switch shortens, overvoltage
Whether whether protection circuit over-pressed to judge to export less than design value by judging the turn-off time of main switch.If in inductance
Electric current does not drop to 0, and grid end flase drop measures negative pressure, main switch conducting, and the turn-off time shortens, and switching circuit is caused to enter by mistake through overvoltage
Guard mode.
Invention content
In view of this, the purpose of the present invention is to provide a kind of control method of switching circuit, control circuit and switch electricity
Source circuit prevents protection false triggering, it is reliable to improve system to solve in the prior art in inductive current zero passage error detection
Property.
Technical solution of the invention is to provide a kind of control method of switching circuit, and the switching circuit includes master
Power tube, rectifying tube and inductance, the control method include：
The main power tube conducting, the rectifying tube shutdown, starts timing, when inductance sample rate current or main power tube sample
When electric current reaches first threshold, timing time is used as at the first time, and reclocking, after the second time, if the electricity
To feel sample rate current or the main power tube sample rate current is more than second threshold, then the switching circuit is in critical conduction mode,
Otherwise the switching circuit is in and is continuously turned on state.
As optional, it is continuously turned on state when the switching circuit is in described, then does not trigger output in this switch periods
Overvoltage protection.
As optional, second time is equal to k times of the first time, and the second threshold is close to first threshold
(k+1) times of value.
As optional, when the main power tube is connected, the rectifying tube shutdown, when the inductance sample rate current or main power
Pipe sample rate current is more than the third threshold value, then the main power tube shutdown, rectifying tube conducting.
As optional, the control method of switching circuit according to claim 4, it is characterised in that：The third threshold value
Equal to the second threshold.
The another technical solution of the present invention is to provide a kind of control method of switching circuit, the switching circuit packet
Main power tube, rectifying tube and inductance are included, the control method includes：
The main power tube conducting, the rectifying tube shutdown, starts timing, when inductance sample rate current or main power tube sample
When electric current reaches four threshold values, timing time is as the 4th time, and reclocking, when inductance sample rate current or main power tube are adopted
When sample electric current reaches five threshold values, timing time is as the 5th time, when being more than the described 5th for n times of the 4th time
Between, the switching circuit is in critical conduction mode, and otherwise the switching circuit is in and is continuously turned on state.
As optional, when the main power tube is connected, the rectifying tube shutdown, when the inductance sample rate current or main power
Pipe sample rate current is more than the 5th threshold value, then the main power tube shutdown, rectifying tube conducting.
As optional, it is continuously turned on state when the switching circuit is in described, then does not trigger output in this switch periods
Overvoltage protection.
The another technical solution of the present invention is to provide a kind of control circuit of switching circuit, the switching circuit packet
Main power tube, rectifying tube and inductance are included, the control circuit controls the main power tube conducting, and starts timing, when inductance is adopted
When sample electric current or main power tube sample rate current reach first threshold, the control circuit timing time is laid equal stress on as at the first time
New timing, after the second time, if the inductance sample rate current or the main power tube sample rate current are more than second threshold,
Then the switching circuit is in critical conduction mode, and otherwise the switching circuit is in and is continuously turned on state.
As optional, the control circuit includes the first comparison circuit, the first timing circuit and logic control circuit,
First timing circuit receives the turn-on and turn-off signal of the main power tube and first comparison circuit
Output voltage,
First comparison circuit receives the inductance sample rate current or main power tube sample rate current and first timing
The output voltage of circuit,
The logic control circuit receives the output voltage of first comparison circuit,
The logic control circuit controls the main power tube conducting, and first timing circuit starts timing, and described the
The one comparison circuit inductance sample rate current or main power tube sample rate current and the first threshold, when the inductance samples
When electric current or main power tube sample rate current reach the first threshold, the first timing circuit timing time is as described first
Time, and reclocking, when the first timing circuit timing is to second time, first comparison circuit is relatively more described
Inductance sample rate current or the main power tube sample rate current and the second threshold, if the inductance sample rate current or the master
Power tube sample rate current is more than the second threshold, then the switching circuit is in critical conduction mode, otherwise the switch electricity
Road is in and is continuously turned on state.
As optional, it is continuously turned on state when the switching circuit is in described, then the logic control circuit is originally being opened
The pass period does not trigger output over-voltage protection.
As optional, k times of second time equal to the first time.
As optional, first timing circuit includes capacitance, the first current source and the second current source, the main power tube
Conducting, the capacitance voltage reset to reference voltage, and first current source charges to the capacitance, when the inductance is adopted
When sample electric current or main power tube sample rate current reach the first threshold, the capacitance is filled in the first current source stopping
Electricity, second current source discharges to the capacitance, described when the capacitance, which powers on pressure, drops to the reference voltage
The first comparison circuit inductance sample rate current or the main power tube sample rate current and the second threshold；
First current source is the first time to the time of the capacitor charging, and second current source is to described
The time of capacitance electric discharge is second time.
As optional, the size of second current source is the size divided by k of first current source.
The another technical solution of the present invention is to provide a kind of switching power circuit.
Circuit structure using the present invention and method have the following advantages compared with prior art：In switching circuit inductance
When current over-zero error detection, protection false triggering is prevented, system reliability is improved.
Description of the drawings
Fig. 1 is the circuit diagram of Buck circuits in the prior art；
Fig. 2 be in the prior art inductive current zero passage error detection when inductive current oscillogram；
Fig. 3 is the inductive current oscillogram in the embodiment of the present invention；
Fig. 4 is inductive current and capacitance voltage oscillogram in the embodiment of the present invention；
Fig. 5 is the module diagram of the switching power circuit in the embodiment of the present invention；
Fig. 6 is the circuit diagram of the first timing circuit in the embodiment of the present invention；
Fig. 7 is the module diagram of the switching power circuit in another embodiment of the present invention；
Fig. 8 is the module diagram of the switching power circuit in another embodiment of the present invention；
Fig. 9 is the inductive current oscillogram in the embodiment of the present invention；
Figure 10 is inductive current and capacitance voltage oscillogram in the embodiment of the present invention；
Figure 11 is the module diagram of the switching power circuit in the embodiment of the present invention；
Figure 12 is the circuit diagram of the second timing circuit in the embodiment of the present invention.
Specific implementation mode
The preferred embodiment of the present invention is described in detail below in conjunction with attached drawing, but the present invention is not restricted to these
Embodiment.The present invention covers any replacement made in the spirit and scope of the present invention, modification, equivalent method and scheme.
In order to make the public have thorough understanding to the present invention, it is described in detail in following present invention preferred embodiment specific
Details, and description without these details can also understand the present invention completely for a person skilled in the art.
The present invention is more specifically described by way of example with reference to attached drawing in the following passage.It should be noted that attached drawing is adopted
Use with more simplified form and non-accurate ratio, only to it is convenient, lucidly aid in illustrating the embodiment of the present invention
Purpose.
The present invention provides a kind of control method of switching circuit, and switching circuit includes main power tube, rectifying tube and inductance, institute
Stating control method includes：The main power tube conducting, the rectifying tube shutdown, starts timing, when inductance sample rate current or main work(
When rate pipe sample rate current reaches first threshold, timing time is used as at the first time, and reclocking, after the second time, such as
Inductance sample rate current described in fruit or the main power tube sample rate current are more than second threshold, then the switching circuit is in critical and leads
Lead to state, otherwise the switching circuit is in and is continuously turned on state.
In switching circuit inductive current zero passage error detection, whether critical conduction mode is in by detection circuit, it can be with
Protection false triggering is prevented, system reliability is improved.
It is inductive current waveform shown in please referring to Fig.3.In t12At the moment, inductive current is more than second threshold, at switching circuit
In critical conduction mode, in t15Moment, inductive current are less than second threshold, and switching circuit is in and is continuously turned on state.
It is continuously turned on state when the switching circuit is in described, then does not trigger output over-voltage protection in this switch periods.
Second time is equal to k times of the first time, (k+1) of the second threshold close to the first threshold
Times.K is more than zero, and preferably, k is less than 1, and second threshold subtracts first threshold and is less than first threshold.
Shown in please referring to Fig.4, when the main power tube is connected, the rectifying tube shutdown, when the inductance sample rate current or
Main power tube sample rate current is more than the third threshold value, then the main power tube shutdown, rectifying tube conducting.
Second threshold is less than or equal to third threshold value.
Third threshold value can be fixed value.In closed-loop control, for third threshold value by compensation signal control, thermal compensation signal is defeated
It is obtained after going out feedback signal and reference signal progress operation amplifier.
In one embodiment, the third threshold value is equal to the second threshold.
Inductive current is characterized by electric current when sampling main power tube conducting.When main power tube is connected, main power tube
Electric current have overshoot, if current over pulse be more than first threshold, at the first time will malfunction.Main power tube is led in order to prevent
Influence of the current over pulse at logical moment to system, is connected in the main power tube, the rectifying tube shutdown, when by lead-edge-blanking
Between after, start timing, when inductance sample rate current or main power tube sample rate current reach first threshold, timing time is as first
Time.
The present invention also provides a kind of control circuit of switching circuit, the switching circuit include main power tube, rectifying tube and
Inductance, the control circuit 100 controls the main power tube conducting, and starts timing, when inductance sample rate current or main power tube
When sample rate current reaches first threshold, 100 timing time of the control circuit is as at the first time, and reclocking, by the
After two times, if the inductance sample rate current or the main power tube sample rate current are more than second threshold, the switch electricity
Road is in critical conduction mode, and otherwise the switching circuit is in and is continuously turned on state.
It please refers to shown in Fig. 5, the control circuit 100 includes the first comparison circuit 120, the first timing circuit 110 and patrols
Volume control circuit 130, first timing circuit 110 receive the turn-on and turn-off signal BON of the main power tube and described
The output voltage V1 of first comparison circuit 120, first comparison circuit 120 receive the inductance sample rate current or main power tube
The output voltage T2 of sample rate current CS and first timing circuit 110, the logic control circuit 130 receive first ratio
Compared with the output voltage of circuit 120, the logic control circuit 130 controls the main power tube conducting, first timing circuit
110 start timing, first comparison circuit, the 120 inductance sample rate current or main power tube sample rate current CS and described
First threshold, when the inductance sample rate current or main power tube sample rate current CS reach the first threshold, the first timing electricity
Road 110 receives the signal that the first comparison circuit 120 characterization CS reaches first threshold, for example, V1 is got higher by low, first timing
110 timing time of circuit is as the first time, and reclocking, 110 timing of the first timing circuit to described second
When the time, the first comparison circuit 120 receives 110 timing of the first timing circuit to the signal T2 of the second time, for example, T2 is by low change
Height, at this point, first comparison circuit, the 120 inductance sample rate current or the main power tube sample rate current CS and described
Second threshold, it is described to open if the inductance sample rate current or the main power tube sample rate current are more than the second threshold
Powered-down road is in critical conduction mode, and otherwise the switching circuit is in and is continuously turned on state.
It is continuously turned on state when the switching circuit is in described, then the logic control circuit 130 is in this switch periods
Do not trigger output over-voltage protection.
Second time is equal to k times of the first time, (k+1) of the second threshold close to the first threshold
Times.K is more than zero, and preferably, k is less than 1, and second threshold subtracts first threshold and is less than first threshold.
It please refers to shown in Fig. 6, first timing circuit 110 includes capacitance C111, the first current source I111 and the second electricity
Stream source I112, main power tube conducting, the voltage amplitude of the capacitance C111 to reference voltage, the first current source I111
It charges to the capacitance C111, when the inductance sample rate current or main power tube sample rate current reach the first threshold
When, the first current source I111 stoppings charge to the capacitance C111, and the second current source I111 is to the capacitance
C111 discharges, and when voltage Vc drops to the reference voltage on the capacitance, first comparison circuit 120 compares institute
State inductance sample rate current or the main power tube sample rate current CS and the second threshold；
The first current source I111 is the first time, second electric current to the time that the capacitance C111 charges
Source I112 is second time to the time that the capacitance C111 discharges.Voltage waveform is as shown in Figure 4 on capacitance C111.
Shown in Fig. 6, the timing circuit 110 further includes logic circuit 111, switch K111 and switch K112,
Comparator 112.Logic circuit 111 receives main power tube turn-on and turn-off signal BON, the output voltage of the first comparison circuit 120
V1, the output control switch K111 and switch K112 of logic circuit, current source I111 and switch K111 random orders are connected, and even
Be connected to voltage source and capacitance C111, current source I112 and switch K112 random orders are connected, and be connected to and capacitance C111, it is electric
The one end for holding C111 is connected to an input terminal of comparator 112, and the other end is connected to ground, another input terminal connection of comparator
To the second reference voltage VR, the output voltage of comparator 112 is the output voltage of timing circuit 110.
When main power tube is connected, the voltage amplitude of the capacitance C111 to the second reference voltage VR, logic circuit 111 is controlled
Switch K111 conductings, switch K112 shutdowns are made, the first current source I111 charges to the capacitance C111, capacitance voltage
Vc rises, and when the inductance sample rate current or main power tube sample rate current reach the first threshold, V1 is got higher by low, logic
The capacitance C111 is filled in circuit controling switch K111 shutdowns, switch K112 conductings, the first current source I111 stoppings
Electricity, the second current source I112 discharge to the capacitance C111, when voltage Vc drops to described second on the capacitance
When reference voltage VR, as reference ground, the output T2 overturnings of comparator 112 characterize timing to the second time in figure 6.
The size of second current source is the size divided by k of first current source.
It please refers to shown in Fig. 7, control circuit 100 further includes the second comparison circuit 150, and second comparison circuit 150 connects
The inductance sample rate current or the main power tube sample rate current CS are received, when the main power tube is connected, the rectifying tube turns off,
After blanking time ahead of the curve, the inductance sample rate current or the main power tube sample rate current CS are compared with third threshold value
Compared with, the logic control circuit 130 receives the output voltage of second comparison circuit 150, when the inductance sample rate current or
Main power tube sample rate current CS is more than the third threshold value, then the logic control circuit 130 control main power tube shutdown,
The rectifying tube conducting.Shown in the inductive current and the waveform of third threshold value please refer to Fig.4.
Shown in Fig. 7, the control circuit further includes inductive current zero cross detection circuit 170.In a reality
It applies in example, the inductive current zero cross detection circuit 170 receives the grid voltage of the main power tube, when inductive current zero passage is examined
Slowdown monitoring circuit detects that the grid voltage is less than zero, then it is assumed that inductive current zero passage.Logic control circuit 130 receives inductive current
The voltage of zero cross detection circuit, when the output voltage of inductive current zero cross detection circuit characterizes inductance zero passage, logic control electricity
Road 130 controls main power tube conducting.In another embodiment, inductive current zero cross detection circuit 170 receives output voltage
The feedback voltage of feedback voltage FB, output voltage are that output voltage is divided by divider resistance.When inductive current zero passage is examined
Slowdown monitoring circuit 170 detects the failing edge or feedback voltage zero passage of feedback voltage, then it is assumed that inductive current zero passage.
Refering to what is shown in Fig. 8, the control circuit 100 further includes operational amplifier 160, the second comparison circuit 150 receives fortune
Calculate the output voltage of amplifier 160.The operational amplifier 160 receives the feedback of output voltage or output current or output power
Voltage FB, operational amplifier 160 carry out operation amplifier to FB and reference voltage VREF, output thermal compensation signal COMP, and described second
Comparison circuit receives thermal compensation signal COMP.The third threshold value is controlled by the thermal compensation signal COMP.
The present invention provides a kind of switching power circuit, including the control circuit 100.
The present invention also provides a kind of control method of switching circuit, the switching circuit include main power tube, rectifying tube and
Inductance, the control method include：The main power tube conducting, the rectifying tube shutdown, starts timing, when inductance sample rate current
Or main power tube sample rate current is when reaching four threshold values, timing time is as the 4th time, and reclocking, when inductance samples electricity
Stream or main power tube sample rate current be when reaching five threshold values, and timing time is n times big when the 4th time as the 5th time
In the 5th time, the switching circuit is in critical conduction mode, and otherwise the switching circuit is in and is continuously turned on state.
In switching circuit inductive current zero passage error detection, whether critical conduction mode is in by detection circuit, it can be with
Protection false triggering is prevented, system reliability is improved.
4th threshold value is less than the 5th threshold value, differences of the 4th threshold value Vth4 equal to the 5th threshold value Vth5 and the 4th threshold value Vth5
M times, i.e. Vth4=m* (Vth5-Vth4), m are more than zero.Preferably, m is more than 1, and close to n.It please refers to shown in Fig. 9,
For inductive current waveform.In t20Moment, main power tube conducting start timing, in t21Moment, inductive current reach the 4th threshold value,
From t20To t21Time be the 4th time, in t22Moment, inductive current reach the 5th threshold value, from t21To t22Time be the 5th
Time.N times of 4th time is more than the 5th time, and the switching circuit is in critical conduction mode.In t23Moment, main work(
Rate pipe is connected, and starts timing, in t24Moment, inductive current reach the 4th threshold value, from t23To t24Time be the 4th time,
t25Moment, inductive current reach the 5th threshold value, from t24To t25Time be the 5th time.N times of 4th time is less than described the
Five times, switching circuit are in and are continuously turned on state.
When the main power tube is connected, the rectifying tube turns off, when the inductance sample rate current or main power tube sampling electricity
Stream is more than the 5th threshold value, then the main power tube shutdown, rectifying tube conducting.That is, the 5th threshold value is
The peak point current of inductive current.In another embodiment, the 5th threshold value can not be peak point current.
It is continuously turned on state when the switching circuit is in described, then does not trigger output over-voltage protection in this switch periods.
Inductive current is characterized by electric current when sampling main power tube conducting.When main power tube is connected, main power tube
Electric current have overshoot, if current over pulse is more than the 4th threshold value, the 4th time will malfunction.Main power tube is led in order to prevent
Influence of the current over pulse at logical moment to system, is connected in the main power tube, the rectifying tube shutdown, when by lead-edge-blanking
Between after, start timing, when inductance sample rate current or main power tube sample rate current reach four threshold values, timing time is as the 4th
Time.
The present invention also provides a kind of control circuit of switching circuit, the switching circuit include main power tube, rectifying tube and
Inductance, the main power tube conducting, the rectifying tube shutdown, control circuit 400 starts timing, when inductance sample rate current or main work(
When rate pipe sample rate current CS reaches four threshold values, the timing time of control circuit 400 is as the 4th time, and reclocking, when
When inductance sample rate current or main power tube sample rate current CS reach five threshold values, control circuit timing time as the 5th time,
N times when the 4th time is more than the 5th time, and the switching circuit is in critical conduction mode, otherwise the switch
Circuit is in and is continuously turned on state.
Please refer to Fig.1 shown in 1, the control circuit 400 further include the second timing circuit 410, the second comparison circuit 420,
Third comparison circuit 430 and logic control circuit 440.
Logic control circuit 440 controls the main power tube conducting, the rectifying tube shutdown, and the second timing circuit 410 is opened
Beginning timing, the 4th comparison circuit 420 receive inductance sample rate current or main power tube sample rate current CS, the 4th threshold value and the 5th threshold
Value, the second timing circuit 410 receive the output signal V4 and V5 of the 4th comparison circuit 420, and the 4th comparison circuit 420 detects electricity
When sense sample rate current or main power tube sample rate current CS reach four threshold values, for example, V4 is got higher by low, the second timing circuit 410
Using timing time as the 4th time, and reclocking.4th comparison circuit 420 detects inductance sample rate current or main power tube
When sample rate current CS reaches five threshold values, for example, V5 is got higher by low, when the timing time of the second timing circuit 410 is as the 5th
Between.Third comparison circuit 430 receives the output voltage Vc2 of the second timing circuit, third comparison circuit 430 by comparing Vc2 and
Third reference voltage VR3, to judge whether n times of the 4th time be more than the 5th time, and output voltage OUT.Example
Such as, n times of the 4th time is more than the 5th time, and OUT is height, and characterization switching circuit is in critical conduction mode；Otherwise table
Sign switching circuit, which is in, is continuously turned on state.Logic control circuit 440 receives the output voltage OUT of third comparison circuit 430.
It is continuously turned on state when the switching circuit is in described, then logic control circuit 440 is not touched in this switch periods
Send out output over-voltage protection.
It please refers to Fig.1 shown in 2, is one embodiment of the second timing circuit 410.Second timing circuit 410 includes electric current
Source I411, I412, capacitance C411.Main power tube is connected, the voltage amplitude of the capacitance C411 to reference voltage, current source I411
It charges to capacitance C411, when the inductance sample rate current or main power tube sample rate current reach four threshold value, electricity
I411 stoppings in stream source charge to the capacitance C411, and current source I412 discharges to the capacitance C411, when the electricity
When sense sample rate current or main power tube sample rate current reach five threshold values, current source I411 and current source I412 stop to capacitance
The charge and discharge of C411.Voltage Vc2 on capacitance C411 is the output voltage of timing circuit 410.Voltage Vc2 on capacitance C411
Waveform is as shown in Figure 10.
It continues to refer to figure 1 shown in 2, the timing circuit 410 further includes logic circuit 411, switch K411 and switch K412.
Logic circuit 411 receives main power tube turn-on and turn-off signal BON, the output voltage V4 and V5 of the second comparison circuit 420, logic
The output control switch K411 and switch K412 of circuit 411, current source I411 and switch K411 random orders are connected, and are connected to
Voltage source and capacitance C411, current source I412 and switch K412 random orders are connected, and be connected to capacitance C411, capacitance
Voltage Vc2 on C411 is the output voltage of timing circuit 410.
When main power tube is connected, the voltage amplitude of the capacitance C411 to third reference voltage VR3, logic circuit 411
Switch K411 conductings are controlled, switch K412 shutdowns, current source I411 charges to the capacitance C411, on capacitance voltage Vc2
It rises, when the inductance sample rate current or main power tube sample rate current reach four threshold value, V4 is got higher by low, logic circuit
411 control switch K411 shutdowns, switch K412 conductings, current source I411 stoppings charge to the capacitance C411, current source
I412 discharges to the capacitance C411, when the inductance sample rate current or main power tube sample rate current reach the 5th threshold
When value, V5 is got higher by low, and logic circuit 111 controls switch K411 and switch K412 is turned off.
Third comparison circuit 430 is comparator.The positive input of comparator is connected to the output Vc2 of the second timing circuit
End, third reference voltage VR3 are connected to for the negative input end of comparator.When Vc2 is more than VR3, the output OUT of comparator is
It is high；When Vc2 is less than VR3, the output OUT of comparator is low.
The control circuit 400 further includes inductive current zero cross detection circuit 170, and logic control circuit 440 receives inductance
The output voltage of current over-zero detection circuit 170.When electricity in the output characterization switching circuit of inductive current zero cross detection circuit 170
Inducing current zero passage, the then control of logic control circuit 440 main power tube conducting.Inductive current zero cross detection circuit 170 is in front
Through being described, details are not described herein.
In addition to this, although embodiment is separately illustrated and is illustrated above, it is related to the common technology in part, in this field
Those of ordinary skill apparently, can be replaced and integrate between the embodiments, be related to one of embodiment and record is not known
Content, then can refer to another embodiment on the books.
Embodiments described above does not constitute the restriction to the technical solution protection domain.It is any in above-mentioned implementation
Modifications, equivalent substitutions and improvements etc., should be included in the protection model of the technical solution made by within the spirit and principle of mode
Within enclosing.
Claims (10)
1. a kind of control method of switching circuit, the switching circuit include main power tube, rectifying tube and inductance, feature exists
In the control method includes：
The main power tube conducting, the rectifying tube shutdown, starts timing, when inductance sample rate current or main power tube sample rate current
When reaching first threshold, timing time is used as at the first time, and reclocking, after the second time, if the inductance is adopted
Sample electric current or the main power tube sample rate current are more than second threshold, then the switching circuit is in critical conduction mode, otherwise
The switching circuit is in and is continuously turned on state.
2. the control method of switching circuit according to claim 1, it is characterised in that：When the switching circuit is in the company
Continuous conducting state, then do not trigger output over-voltage protection in this switch periods.
3. the control method of switching circuit according to claim 1, it is characterised in that：Second time is equal to described first
K times of time, (k+1) times of the second threshold close to the first threshold.
4. according to the control method of switching circuit described in claim 1-3 any one, it is characterised in that：When the main power tube
Conducting, rectifying tube shutdown, when the inductance sample rate current or main power tube sample rate current are more than the third threshold value, then institute
State main power tube shutdown, rectifying tube conducting.
5. the control method of switching circuit according to claim 4, it is characterised in that：The third threshold value is equal to described second
Threshold value.
6. a kind of control method of switching circuit, the switching circuit include main power tube, rectifying tube and inductance, feature exists
In the control method includes：
The main power tube conducting, the rectifying tube shutdown, starts timing, when inductance sample rate current or main power tube sample rate current
When reaching four threshold values, timing time is as the 4th time, and reclocking, when inductance sample rate current or main power tube sampling electricity
When stream reaches five threshold values, timing time is more than the 5th time, institute as the 5th time, n times when the 4th time
It states switching circuit and is in critical conduction mode, otherwise the switching circuit is in and is continuously turned on state.
7. the control method of switching circuit according to claim 6, it is characterised in that：It is described when main power tube conducting
Rectifying tube turns off, when the inductance sample rate current or main power tube sample rate current are more than the 5th threshold value, then the main power
Pipe shutdown, rectifying tube conducting.
8. the control method of switching circuit according to claim 6, it is characterised in that：When the switching circuit is in the company
Continuous conducting state, then do not trigger output over-voltage protection in this switch periods.
9. a kind of control circuit of switching circuit, the switching circuit include main power tube, rectifying tube and inductance, feature exists
In：The control circuit controls the main power tube conducting, and starts timing, when inductance sample rate current or main power tube sampling electricity
When stream reaches first threshold, the control circuit timing time is used as at the first time, and reclocking, after the second time,
If the inductance sample rate current or the main power tube sample rate current are more than second threshold, the switching circuit is in critical
Conducting state, otherwise the switching circuit be in be continuously turned on state.
10. the control circuit of switching circuit according to claim 9, it is characterised in that：The control circuit includes the first ratio
Compared with circuit, the first timing circuit and logic control circuit,
First timing circuit receive the main power tube turn-on and turn-off signal and first comparison circuit it is defeated
Go out voltage,
First comparison circuit receives the inductance sample rate current or main power tube sample rate current and first timing circuit
Output voltage,
The logic control circuit receives the output voltage of first comparison circuit,
The logic control circuit controls the main power tube conducting, and first timing circuit starts timing, first ratio
Compared with the circuit inductance sample rate current or main power tube sample rate current and the first threshold, when the inductance sample rate current
Or main power tube sample rate current is when reaching the first threshold, when the first timing circuit timing time is as described first
Between, and reclocking, when the first timing circuit timing is to second time, the first comparison circuit electricity
Sample rate current or the main power tube sample rate current and the second threshold are felt, if the inductance sample rate current or the main work(
Rate pipe sample rate current is more than the second threshold, then the switching circuit is in critical conduction mode, otherwise the switching circuit
In being continuously turned on state.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810208098.8A CN108365739A (en) | 2018-03-14 | 2018-03-14 | A kind of control method of switching circuit, control circuit and switching power circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810208098.8A CN108365739A (en) | 2018-03-14 | 2018-03-14 | A kind of control method of switching circuit, control circuit and switching power circuit |
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| CN108365739A true CN108365739A (en) | 2018-08-03 |
Family
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810208098.8A Pending CN108365739A (en) | 2018-03-14 | 2018-03-14 | A kind of control method of switching circuit, control circuit and switching power circuit |
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| CN (1) | CN108365739A (en) |
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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 Applicant after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 424, building 1, 1500 Wenyi West Road, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province Applicant before: JOULWATT TECHNOLOGY Inc.,Ltd. |