CN103916020B - Switching Power Supply and control circuit thereof - Google Patents
Switching Power Supply and control circuit thereof Download PDFInfo
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- CN103916020B CN103916020B CN201410164522.5A CN201410164522A CN103916020B CN 103916020 B CN103916020 B CN 103916020B CN 201410164522 A CN201410164522 A CN 201410164522A CN 103916020 B CN103916020 B CN 103916020B
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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
- H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
- H02M1/4208—Arrangements for improving power factor of AC input
- H02M1/4266—Arrangements for improving power factor of AC input using passive elements
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
A kind of Switching Power Supply and control circuit thereof, the control circuit of described Switching Power Supply includes peak current detection end, feedback end, drive end, the first voltage comparator and pwm unit, also includes: control end, is suitable to receive control voltage；Reference voltage adjustment unit, is suitable to produce peakedness ratio relatively reference voltage according to described control voltage: when the magnitude of voltage at described control voltage is equal to 0V or is more than the first magnitude of voltage, described peakedness ratio is the second magnitude of voltage compared with the magnitude of voltage of reference voltage；When the magnitude of voltage of described control voltage is more than 0V and the most described first magnitude of voltage, described peakedness ratio is compared with the magnitude of voltage of reference voltage equal to third voltage value and the magnitude of voltage sum of described control voltage, and described third voltage value and described first magnitude of voltage sum are equal to described second magnitude of voltage.The Switching Power Supply of present invention offer and control circuit thereof, reduce the total harmonic distortion of described Switching Power Supply.
Description
Technical field
The present invention relates to electric and electronic technical field, particularly to a kind of Switching Power Supply and control circuit thereof.
Background technology
Switching Power Supply is to utilize modern power electronics technology, controls the time that switching transistor turns on and off
Ratio, maintains a kind of power supply of stable output.Along with development and the innovation of Power Electronic Technique, switch electricity
Source technology is also innovated constantly.At present, Switching Power Supply with small-sized, light weight and high efficiency feature by extensively
The almost all of electronic equipment of general application, is that current electronics and information industry develops rapidly indispensable one
Power mode.Whether direct-current switch power supply has electrical isolation can be divided into two classes by between input with output:
Isolation type switching power supply and non-isolated Switching Power Supply.
Fig. 1 is the structural representation of common a kind of isolation type switching power supply, and described Switching Power Supply includes rectification
Bridge 10, primary filter capacitor 11, transformator 12, switching transistor 13, sampling resistor 14, control circuit
15, commutation diode 16 and secondary filter capacitor 17, wherein, described control circuit 15 is the most integrated
Circuit.Described control circuit 15 includes peak current detection end CS, feedback end FB, drive end DRV, electricity
Pressure comparator 151 and pwm unit 152.In described Switching Power Supply, each device specifically connects pass
System, with reference to shown in Fig. 1, does not repeats them here.
It is whole that described rectifier bridge 10 is suitable to that the AC-input voltage Vac inputting described Switching Power Supply is carried out all-wave
Stream, is become unidirectional pulsation electricity by described AC-input voltage Vac by positive and negative sinusoidal voltage rectification alternately
Pressure；Described primary filter capacitor 11 is suitable to the pulsating volage of described rectifier bridge 10 output is carried out smothing filtering,
Produce smooth DC input voitage Vbus；Described transformator 12 is suitable to by certain voltage ratio it is primary
The voltage induced at coil two ends is to its secondary coil；Described switching transistor 13 is suitable at described drive end
On or off under the control of the driving voltage that DRV provides；Described sampling resistor 14 is suitable to flowing through described
The electric current of switching transistor 13 is converted to voltage and transmits to described peak current detection end CS；Described control
Circuit 15 is suitable to the voltage according to described peak current detection end CS and the feedback signal of described feedback end FB
Described driving voltage is provided；Described commutation diode 16 and described secondary filter capacitor 17 are suitable to described change
The voltage at the secondary coil two ends of depressor 12 carries out rectification and filtering, with the outfan in described Switching Power Supply
Out produces constant voltage or electric current.
The feedback signal of described feedback end FB is provided by feedback circuit.Owing to described Switching Power Supply has multiple
Feedback model, correspondingly, described feedback circuit also has multiple circuit structure.Therefore, Fig. 1 is not given
The particular circuit configurations of described feedback circuit.In order to meet the load request of described Switching Power Supply, described control
Circuit 15 processed has power regulation functions.Specifically, it is more than when the voltage of described peak current detection end CS
During preset peakedness ratio relatively reference voltage V ref, represent the output of described Switching Power Supply beyond preset
Output, the comparison letter that described pwm unit 152 exports according to described voltage comparator 151
Number produce low level driving voltage, by described drive end DRV output to described switching transistor 13
Grid, controls described switching transistor 13 and ends；When described peak current detection end CS voltage less than or
During equal to described peakedness ratio relatively reference voltage V ref, represent that the output of described Switching Power Supply is without departing from preset
Output, anti-by described feedback end FB of driving voltage that described pwm unit 152 produces
Feedback signal determines.
When described switching transistor 13 turns on, primary current Ip through described transformator 12 primary coil,
Described switching transistor 13 and described sampling resistor 14 are to ground, the primary coil energy storage of described transformator 12；
When described switching transistor 13 is ended, it is stored in the energy in the primary coil of described transformator 12 through magnetic
Road coupled to the secondary coil of described transformator 12, through the rectification of described commutation diode 16 and described time
The filtering of level filter capacitor 17, produces constant voltage or electric current at described outfan out.
In order to reduce grid loss and pollution, the power factor (PF) (PF, Power Factor) of Switching Power Supply and
Total harmonic distortion (THD, Total Harmonic Distortion) needs to meet certain requirement.For figure
Switching Power Supply shown in 1, when its system power applied is less, can fill out paddy (Valley by increase
Fill) circuit improves its power factor (PF) and total harmonic distortion.Fig. 2 is that paddy is filled out in the Switching Power Supply increase shown in Fig. 1
The structural representation of circuit, valley fill circuit 20 includes first electric capacity the 201, second electric capacity the 202, the 1st pole
Pipe the 203, second diode 204 and the 3rd diode 205.Those skilled in the art fill out paddy electricity described in knowing
The operation principle on road 20, does not repeats them here.
After using described valley fill circuit 20, the power factor of described Switching Power Supply is improved, and meets phase
Close the requirement of technical specification.Fig. 3 be the Switching Power Supply shown in Fig. 2 input current frequency domain launch after each time
The scattergram of harmonic current, abscissa is frequency, unit: KHz (kHz)；Vertical coordinate is input electricity
Stream, unit: milliampere (mA).From the input current waveform of described Switching Power Supply it can be seen that described in open
Close the input current of power supply on the basis of fundametal compoment, a lot of higher harmonic components of superposition.Bigger
Higher harmonic components (such as 7 order harmonic components and 13 order harmonic components) exists, and causes described Switching Power Supply
Total harmonic distortion cannot meet the requirement of associated specifications.
In order to improve the total harmonic distortion of described Switching Power Supply further, by filling out described in prior art
Paddy circuit 20 increases resistance to adjust the input current of described Switching Power Supply, the circuit of described Switching Power Supply
Structure is as shown in Figure 4.Described valley fill circuit also includes current-limiting resistance 206, and described current-limiting resistance 206 is with described
3rd diode 205 is connected.Owing to described current-limiting resistance 206 can reduce the input electricity of described Switching Power Supply
Stream, the total harmonic distortion of described Switching Power Supply can be reduced, but still can not make described Switching Power Supply
Total harmonic distortion meet the requirement of associated specifications.Further, described current-limiting resistance 206 is in described
In the charge circuit of one electric capacity 201 and described second electric capacity 202 so that described first electric capacity 201 and described
The charging current of two electric capacity 202 reduces, and adds loss during charging, causes the efficiency of described Switching Power Supply
Reduce.Therefore, in the case of not reducing described switch power efficiency, how to reduce total harmonic distortion to be still
One problem demanding prompt solution.
Summary of the invention
What the present invention solved is the problem that Switching Power Supply total harmonic distortion is high.
For solving the problems referred to above, the present invention provides the control circuit of a kind of Switching Power Supply, including peak point current
Test side, feedback end, drive end, the first voltage comparator and pwm unit, also include:
Control end, be suitable to receive control voltage；
Reference voltage adjustment unit, is suitable to according to described control voltage generation peakedness ratio relatively reference voltage:
When magnitude of voltage at described control voltage is equal to 0V or is more than the first magnitude of voltage, described peakedness ratio is relatively
The magnitude of voltage of reference voltage is the second magnitude of voltage；
When the magnitude of voltage of described control voltage is more than 0V and the most described first magnitude of voltage, described peak value
The magnitude of voltage of benchmark voltage is equal to the magnitude of voltage sum of third voltage value with described control voltage, described
Third voltage value and described first magnitude of voltage sum are equal to described second magnitude of voltage.
Optionally, described reference voltage adjustment unit includes:
Clamping unit, is suitable to described control when the magnitude of voltage of described control end is more than described first magnitude of voltage
The magnitude of voltage of end processed is limited to described first magnitude of voltage；
Second voltage comparator, is suitable to compare the voltage of 0V voltage and described control end to produce ratio
Relatively level, produces the first comparative level when the voltage of described control end is more than 0V voltage, otherwise produces the
Two comparative levels；
Select unit, be suitable to receive the first reference voltage, the voltage of described control end and described second electricity
The comparative level that pressure comparator produces, selects described control end when receiving described first comparative level
Voltage exports, and selects described first reference voltage output when receiving described second comparative level, described
The magnitude of voltage of the first reference voltage is equal to described first magnitude of voltage；
Adder, the voltage being suitable to superposition the second reference voltage and the output of described selection unit is described to produce
Peakedness ratio relatively reference voltage, the magnitude of voltage of described second reference voltage is equal to described third voltage value.
Control circuit based on above-mentioned Switching Power Supply, the present invention also provides for a kind of Switching Power Supply, including rectification
Bridge, valley fill circuit and switching transistor, also include:
The control circuit of above-mentioned Switching Power Supply；
Sample circuit, the voltage being suitable to the half-wave voltage signal node to described valley fill circuit samples to produce
Described control voltage.
Compared with prior art, technical scheme has the advantage that
The Switching Power Supply of technical solution of the present invention offer and control circuit thereof, by described control circuit
Arranging reference voltage adjustment unit, producing magnitude of voltage can change with the AC-input voltage of described Switching Power Supply
And the peakedness ratio changed relatively reference voltage.When DC input voitage is relatively low, described reference voltage adjusts single
The peakedness ratio relatively reference voltage that unit produces reduces accordingly.Maximum due to the primary current of described Switching Power Supply
Current value and described peakedness ratio relatively reference voltage are proportionate change, the reduction of described peakedness ratio relatively reference voltage
The maximum current value making described primary current reduces, so that the AC input current of described Switching Power Supply
Waveform is smoothened, will not produce current break phenomenon, reduces the total harmonic distortion of described Switching Power Supply.
Further, described Switching Power Supply is the voltage of half-wave voltage signal node in valley fill circuit to carry out sampling obtain described
The control voltage of control circuit, this kind of sample mode is the simplest, it is simple to described control circuit follows the tracks of exchange
The change of input voltage, can simplify the structure of described control circuit.
Further, the control circuit highly versatile of the Switching Power Supply that the present invention provides, it is applicable to inhomogeneity
The Switching Power Supply of type, described Switching Power Supply can be isolation type switching power supply (such as inverse-excitation type switch power-supply),
Can also be non-isolated Switching Power Supply (such as buck boost switcher power supply and step down switching regulator), fall
The low cost of described Switching Power Supply.
In the alternative of the present invention, described reference voltage adjustment unit includes clamping unit, the second voltage
Comparator, selection unit and adder, described clamping unit includes Zener diode.Described voltage stabilizing two
The simple in construction of pole pipe, saves the area of described control circuit.
In the alternative of the present invention, described clamping unit includes transistor and operational amplifier.Due to institute
State operational amplifier and there is higher gain, when the magnitude of voltage controlling end of described control circuit is more than setting
The first magnitude of voltage time, described operational amplifier can output control signals to described transistor rapidly
Control electrode, control described transistor turns, described control end is shunted, thus rapidly to institute
State control end and carry out clamper, improve the described peakedness ratio precision compared with reference voltage.
In the alternative of the present invention, described transistor is PNP triode.Due to described PNP triode
There is Current amplifier function, it is possible to the control signal inputted its base stage rapidly responds, rapidly
Described control end is carried out clamper.
Accompanying drawing explanation
Fig. 1 is the structural representation of existing a kind of Switching Power Supply；
Fig. 2 is the structural representation of existing another kind of Switching Power Supply；
Fig. 3 be the Switching Power Supply shown in Fig. 2 input current frequency domain launch after individual harmonic current point
Butut；
Fig. 4 is the structural representation of existing another kind of Switching Power Supply；
Fig. 5 is the AC-input voltage of the Switching Power Supply shown in Fig. 2, DC input voitage, half-wave voltage signal
Node voltage, peakedness ratio are compared with the time dependent waveform diagram of reference voltage and AC input current；
Fig. 6 is the structural representation of the Switching Power Supply of embodiment of the present invention；
Fig. 7 is the AC-input voltage of the Switching Power Supply of embodiment of the present invention, DC input voitage, control
Voltage processed, peakedness ratio are compared with the time dependent waveform diagram of reference voltage and AC input current；
Fig. 8 is the input current of the Switching Power Supply of embodiment of the present invention each harmonic electricity after frequency domain launches
The scattergram of stream；
Fig. 9 is the structural representation of a kind of Switching Power Supply that the embodiment of the present invention provides；
Figure 10 be the embodiment of the present invention provide control voltage, control the voltage of end, comparative level, second
Reference voltage and peakedness ratio are compared with the time dependent waveform diagram of reference voltage；
Figure 11 is the structural representation of a kind of clamping unit that the embodiment of the present invention provides；
Figure 12 is the structural representation of the another kind of clamping unit that the embodiment of the present invention provides；
Figure 13 is the structural representation of the another kind of clamping unit that the embodiment of the present invention provides；
Figure 14 is a kind of structural representation selecting unit that the embodiment of the present invention provides；
Figure 15 is the structural representation of the another kind of Switching Power Supply that the embodiment of the present invention provides；
Figure 16 is the structural representation of the another kind of Switching Power Supply that the embodiment of the present invention provides.
Detailed description of the invention
The higher hamonic wave that Switching Power Supply produces can produce Conduction Interference and radiation interference along grid power transmission circuit,
Thus electric power system is produced and pollutes and to affect other properly functioning in road electrical equipment.Therefore, no matter from
The safe operation of protection electrical network, or from the point of view of electrical equipment normally works, reduce the harmonic wave dirt to electrical network
Dye, suppression electromagnetic interference have become industry question of common concern.Switching Power Supply produces the former of higher hamonic wave
The exchange input electricity that in cause mainly Switching Power Supply, commonly used capacitor filtering type bridge rectifier causes
There is wave distortion in stream.
Although the Switching Power Supply shown in Fig. 2 adds valley fill circuit 20, but its total harmonic distortion still cannot
Meet the requirement of associated specifications.Fig. 5 be the Switching Power Supply shown in Fig. 2 AC-input voltage Vac,
DC input voitage Vbus, the voltage VH of half-wave voltage signal node N0, peakedness ratio relatively reference voltage V ref
And the waveform diagram of AC input current Iac t in time change, described AC-input voltage Vac,
DC input voitage Vbus, half-wave voltage signal node N0 voltage VH and AC input current Iac all in
Cyclically-varying.Wherein, the frequency of described AC-input voltage Vac and described AC input current Iac
Frequency is identical, the frequency of described DC input voitage Vbus and the voltage VH of described half-wave voltage signal node N0
Frequency identical, the frequency of described DC input voitage Vbus is the frequency of described AC-input voltage Vac
Twice.
Owing to described AC-input voltage Vac is in periodically variable, described Switching Power Supply worked
Journey is also in cyclically-varying.As a example by half working cycle T0 of described AC-input voltage Vac, below
In conjunction with Fig. 2, waveform each in Fig. 5 is described in detail.Amplitude according to described AC-input voltage Vac
Situation of change, described half working cycle T0 includes four moment: the first moment t1, the second moment t2,
3rd moment t3 and the 4th moment t4.Described first moment t1 is rising of described half working cycle T0
Beginning the moment, at described first moment t1, the amplitude of described AC-input voltage Vac is zero；From described
One moment t1 starts, and the amplitude of described AC-input voltage Vac constantly increases, to described second moment t2
Time, the amplitude of described AC-input voltage Vac is increased to the half of peak value Upk；Described exchange input electricity
The amplitude of pressure Vac continues to increase, and constantly reduces after reaching peak value Upk, during to described 3rd moment t3,
The amplitude of described AC-input voltage Vac is reduced to the half of peak value Upk；Described AC-input voltage Vac
Amplitude continue reduce, during to described 4th moment t4, the amplitude of described AC-input voltage Vac is reduced to
Zero, described half working cycle T0 terminates.
Between described first moment t1 and described second moment t2, due to described 3rd diode 205
Unilateal conduction effect, described first electric capacity 201 and described second electric capacity 202 are in parallel discharge state,
The amplitude of the voltage VH of described half-wave voltage signal node N0 is zero.The electricity of the load consumption of described Switching Power Supply
Can be provided by described first electric capacity 201 and described second electric capacity 202 completely, thus described exchange input electricity
The amplitude of stream Iac is zero.Owing to the load of described Switching Power Supply constantly consumes electric energy, described direct current input electricity
The amplitude of pressure Vbus constantly reduces.During to described second moment t2, described DC input voitage Vbus's
Amplitude is down to minimum.
Between described second moment t2 and described 3rd moment t3, the load consumption of described Switching Power Supply
Electric energy is provided by described AC-input voltage Vac, and it is defeated that described DC input voitage Vbus follows described exchange
Enter voltage Vac change.Further, the amplitude at described AC-input voltage Vac reaches near peak value Upk,
Described AC-input voltage Vac not only provides the energy of the load consumption of described Switching Power Supply, also by institute
State the 3rd diode 205 to turn on described first electric capacity 201 and described second electric capacity 202 are charged, therefore,
The amplitude of described AC input current Iac reaches peak value.
Between described 3rd moment t3 and described 4th moment t4, described first electric capacity 201 and described
Two electric capacity 202 parallel discharges again, the electric energy of the load consumption of described Switching Power Supply is completely by described first
Electric capacity 201 and described second electric capacity 202 provide, and the amplitude of described DC input voitage Vbus constantly reduces.
The described Switching Power Supply duty when described AC-input voltage Vac is in negative half period with in described friendship
Duty when stream input voltage Vac is in positive half cycle is similar to, and does not repeats them here.
In prior art, when the load of described Switching Power Supply is constant, the input power of described Switching Power Supply
Being invariable, the most described peakedness ratio is compared with the voltage value constant of reference voltage V ref.When described second
Carving t2 and described 3rd moment t3, the amplitude of described DC input voitage Vbus falls too low, according to merit
Rate is equal to the product of voltage with electric current, and the amplitude of described primary current Ip is the highest, causes described exchange defeated
Enter electric current Iac to undergo mutation at described second moment t2 and described 3rd moment t3, produce bigger spike
Electric current, the total harmonic distortion causing described Switching Power Supply is high.
Technical solution of the present invention provides a kind of Switching Power Supply and control circuit thereof, by described control circuit
In reference voltage adjustment unit is set, producing magnitude of voltage can become with the AC-input voltage of described Switching Power Supply
The peakedness ratio relatively reference voltage changed and change, makes the waveform of the AC input current of described Switching Power Supply become
Smooth, current break phenomenon will not be produced, reduce the total harmonic distortion of described Switching Power Supply.
Fig. 6 is the structural representation of the Switching Power Supply of embodiment of the present invention, and described Switching Power Supply includes whole
Stream bridge 60, transformator 62, switching transistor 63, sampling resistor 64, control circuit 65, rectification two pole
Pipe 66, secondary filter capacitor 67, valley fill circuit 68 and sample circuit 69, wherein, described rectifier bridge
60, described transformator 62, described switching transistor 63, described sampling resistor 64, described commutation diode
66 and described secondary filter capacitor 67 concrete structure with function similarly to the prior art, the most superfluous at this
State.
Described sample circuit 69 is suitable to the voltage VH of the half-wave voltage signal node N0 to described valley fill circuit 68
Carry out sampling and control voltage Vctr to produce.Specifically, described valley fill circuit 68 include the first electric capacity 681,
Second electric capacity the 682, first diode the 683, second diode 684 and the 3rd diode 685, described
Half-wave voltage signal node N0 is described first electric capacity 681, described first diode 683 and the described 3rd 2
The connection node of pole pipe 685.Owing to described control voltage Vctr is to described half-wave voltage signal node N0
Voltage VH carry out sampling obtain, described control voltage Vctr can with a voltage ratio set in advance with
With described half-wave voltage signal node N0 voltage VH change, such as, set described control voltage Vctr with
The voltage ratio of the voltage VH of described half-wave voltage signal node N0 is 1:100, when described half-wave voltage signal node
When the voltage VH of N0 is 100V, described control voltage Vctr is 1V.Described voltage ratio can be by reality
Demand is configured, and this is not construed as limiting by the present invention.
Described control circuit 65 include peak current detection end CS, feedback end FB, drive end DRV,
One voltage comparator 651, pwm unit 652, control end CTR and reference voltage adjust
Unit 653.Described peak current detection end CS, described feedback end FB, described drive end DRV, institute
State the concrete structure of the first voltage comparator 651 and described pwm unit 652 and function with
Prior art is similar to, and does not repeats them here.
Described control end CTR is suitable to receive described control voltage Vctr, the most described control end CTR and is suitable to
Receive the voltage VH to described half-wave voltage signal node N0 and carry out the voltage that sampling obtains, described control end
CTR connects described sample circuit 69 and exports the outfan of described control voltage Vctr.Described reference voltage
Adjustment unit 653 is suitable to produce peakedness ratio relatively reference voltage V ref according to described control voltage Vctr, described
Peakedness ratio relatively reference voltage V ref is controlled by described control voltage Vctr.Specifically, at described control voltage
The magnitude of voltage of Vctr is equal to 0V or when the magnitude of voltage of described control voltage Vctr is more than the first magnitude of voltage,
Described peakedness ratio is the second magnitude of voltage compared with the magnitude of voltage of reference voltage V ref；Described control voltage Vctr's
When the magnitude of voltage magnitude of voltage more than 0V and described control voltage Vctr is not more than described first magnitude of voltage,
Described peakedness ratio is equal to third voltage value and described control voltage Vctr's compared with the magnitude of voltage of reference voltage V ref
Magnitude of voltage sum.Wherein, described third voltage value and described first magnitude of voltage sum are equal to described second electricity
Pressure value.
Described first magnitude of voltage, described second magnitude of voltage and described third voltage value all can be according to reality
Demand is set, the invention is not limited in this regard.Further, described second magnitude of voltage and prior art
In peakedness ratio compared with reference voltage magnitude of voltage be similar to, it is relevant to the output of described Switching Power Supply:
If the output of described Switching Power Supply is relatively big, described second magnitude of voltage arranges bigger；If described switch
The output of power supply is less, and described second magnitude of voltage arranges less.Those skilled in the art know as
What sets described second magnitude of voltage according to the performance number of the output of described Switching Power Supply, the most superfluous at this
State.Described first magnitude of voltage is the threshold value set, and saves with described half-wave voltage signal at described control voltage Vctr
When the voltage ratio of the voltage VH of some N0 determines, the total harmonic distortion of described Switching Power Supply and described first
Magnitude of voltage is correlated with: described first magnitude of voltage arranges the biggest, and the total harmonic distortion of described Switching Power Supply is the least.
Therefore, it can basis require to determine described first magnitude of voltage to the total harmonic distortion of described Switching Power Supply.
Fig. 7 is the AC-input voltage Vac of the Switching Power Supply of embodiment of the present invention, DC input voitage
Vbus, control voltage Vctr, peakedness ratio relatively reference voltage V ref and AC input current Iac are in time
The waveform diagram of change, each voltage and electric current are all in cyclically-varying.Wherein, described exchange input electricity
The frequency of pressure Vac is identical with the frequency of described AC input current Iac, described DC input voitage Vbus
Frequency, control the frequency of voltage Vctr and peakedness ratio is identical compared with the frequency of reference voltage V ref, described
The frequency of DC input voitage Vbus is the twice of the frequency of described AC-input voltage Vac.
Or as a example by half working cycle T0' of described AC-input voltage Vac, below in conjunction with Fig. 6 pair
In Fig. 7, each waveform is described in detail.According to the amplitude of variation situation of described AC-input voltage Vac,
Described half working cycle T0' includes six moment: the first moment t1', the second moment t2', the 3rd moment
T3', the 4th moment t4', the 5th moment t5' and the 6th moment t6'.
Described first moment t1' is the initial time of described half working cycle T0', in described first moment
T1', the amplitude of described AC-input voltage Vac is zero；From the beginning of described first moment t1', described exchange
The amplitude of input voltage Vac constantly increases, during to described second moment t2', and described AC-input voltage Vac
Amplitude be increased to the half of peak value Upk；The amplitude of described AC-input voltage Vac continues to increase, and arrives
During described 3rd moment t3', the magnitude of voltage of described control voltage Vctr is increased to described first magnitude of voltage U1；
The amplitude of described AC-input voltage Vac continues to increase, and constantly reduces, to described after reaching peak value Upk
During the 4th moment t4', the magnitude of voltage of described control voltage Vctr is reduced to described first magnitude of voltage U1；Institute
The amplitude stating AC-input voltage Vac continues to reduce, and during to described 4th moment t5', described exchange inputs
The amplitude of voltage Vac is reduced to the half of peak value Upk；The amplitude of described AC-input voltage Vac continues
Reducing, during to described 6th moment t6', the amplitude of described AC-input voltage Vac reduces to zero, described half
Individual working cycle T0' terminates.
Between described first moment t1' and described second moment t2', due to described 3rd diode 685
Unilateal conduction effect, described first electric capacity 681 and described second electric capacity 682 are in parallel discharge state,
The magnitude of voltage of the voltage VH of described half-wave voltage signal node N0 is zero, follows described half-wave voltage signal node N0
The magnitude of voltage of control voltage Vctr of voltage VH change be also zero.Therefore, described reference voltage adjusts
The described peakedness ratio that unit 653 produces is the second magnitude of voltage U2 compared with the magnitude of voltage of reference voltage V ref.Described
The electric energy of the load consumption of Switching Power Supply is carried by described first electric capacity 681 and described second electric capacity 682 completely
Confession, the amplitude of described AC input current Iac is zero.Owing to the load of described Switching Power Supply constantly consumes electricity
Can, the amplitude of described DC input voitage Vbus constantly reduces.During to described second moment t2', described directly
The amplitude of stream input voltage Vbus is down to minimum.
Between described second moment t2' and described 3rd moment t3', the load consumption of described Switching Power Supply
Electric energy is provided by described AC-input voltage Vac, and it is defeated that described DC input voitage Vbus follows described exchange
Entering voltage Vac change, the magnitude of voltage of the voltage VH of described half-wave voltage signal node N0 constantly increases, and follows
The magnitude of voltage of the control voltage Vctr of the voltage VH change of described half-wave voltage signal node N0 the most constantly increases,
And the magnitude of voltage of described control voltage Vctr is not more than described first magnitude of voltage U1.Therefore, described benchmark electricity
The described peakedness ratio that pressure adjustment unit 653 produces is equal to third voltage value compared with the magnitude of voltage of reference voltage V ref
The magnitude of voltage sum of U3 and described control voltage Vctr.
Owing to described peakedness ratio is increased to by described third voltage value U3 compared with the magnitude of voltage of reference voltage V ref
Described first magnitude of voltage U1, between described second moment t2' and described 3rd moment t3', described switch electricity
The input power in source is slowly varying.Compared with prior art, the primary current of described Switching Power Supply
Maximum current value reduces, and the waveform making described AC input current Iac is smoothened, it is to avoid generation electric current
Jumping phenomenon.
Between described 3rd moment t3' and described 4th moment t4', the load consumption of described Switching Power Supply
Electric energy is still provided by described AC-input voltage Vac, and the magnitude of voltage of described control voltage Vctr is more than described
First magnitude of voltage U1.Therefore, the described peak value benchmark that described reference voltage adjustment unit 653 produces
The magnitude of voltage of voltage Vref is equal to described second magnitude of voltage U2.Amplitude at described AC-input voltage Vac
Reaching near peak value Upk, described AC-input voltage Vac not only provides the load of described Switching Power Supply to disappear
The energy of consumption, turns on described first electric capacity 681 and described second also by described 3rd diode 685
Electric capacity 682 charges, and the amplitude of described AC input current Iac reaches peak value.
Between described 4th moment t4' and described 5th moment t5', the magnitude of voltage of described control voltage Vctr
It is again positioned between 0V and described first magnitude of voltage U1.Therefore, described peakedness ratio relatively reference voltage V ref
The magnitude of voltage magnitude of voltage sum equal to third voltage value U3 and described control voltage Vctr, make described friendship
The waveform of stream input current Iac is smoothened.
Between described 5th moment t5' and described 6th moment t6', described first electric capacity 681 and described
Two electric capacity 682 parallel discharges again, the electric energy of the load consumption of described Switching Power Supply is completely by described first
Electric capacity 681 and described second electric capacity 682 provide, and the amplitude of described DC input voitage Vbus constantly reduces.
The magnitude of voltage of the voltage VH of described half-wave voltage signal node N0 is zero, follows described half-wave voltage signal node N0
The magnitude of voltage of control voltage Vctr of voltage VH change be also zero.Therefore, described reference voltage adjusts
The described peakedness ratio that unit 653 produces is the second magnitude of voltage U2 compared with the magnitude of voltage of reference voltage V ref.Described
The Switching Power Supply duty when described AC-input voltage Vac is in negative half period with described exchange defeated
Enter duty when voltage Vac is in positive half cycle to be similar to, do not repeat them here.
Different compared with reference voltage from arranging constant peakedness ratio in prior art, embodiment of the present invention provides
Switching Power Supply and control circuit, by the voltage VH of described half-wave voltage signal node N0 is sampled
Obtain described control voltage Vctr, then it is single to control the adjustment of described reference voltage by described control voltage Vctr
Unit 653 obtains peakedness ratio relatively reference voltage V ref of magnitude of voltage change.At described second moment t2' with described
Between 3rd moment t3' and between described 4th moment t4' and described 5th moment t5', described peakedness ratio
Relatively reference voltage V ref reduces with the voltage VH of described half-wave voltage signal node N0 and reduces, described switch
The amplitude reduction of the primary current of power supply, makes described AC input current Iac smoothened, without peak current
Produce, reduce the total harmonic distortion of described Switching Power Supply.
Fig. 8 is the input current of the Switching Power Supply of embodiment of the present invention each harmonic electricity after frequency domain launches
The scattergram of stream, abscissa is frequency, unit: KHz (kHz)；Vertical coordinate is input current, single
Position: milliampere (mA).From figure 8, it is seen that compared with the Switching Power Supply of prior art, the present invention is real
Each higher harmonic components of the Switching Power Supply executing mode is decreased obviously, the total harmonic distortion of described Switching Power Supply
Corresponding reduction.
Understandable, below in conjunction with the accompanying drawings for enabling the above-mentioned purpose of the present invention, feature and advantage to become apparent from
The specific embodiment of the present invention is described in detail.
Fig. 9 is the structural representation of a kind of Switching Power Supply that the embodiment of the present invention provides, described Switching Power Supply
Including rectifier bridge 90, transformator 92, switching transistor 93, sampling resistor 94, control circuit 95, whole
Stream diode 96, secondary filter capacitor 97, valley fill circuit 98 and sample circuit 99, wherein, described
Control circuit 95 includes peak current detection end CS, feedback end FB, drive end DRV, the first voltage ratio
Relatively device 951, pwm unit 952, control end CTR and reference voltage adjustment unit 953.
Specifically, in the present embodiment, described sample circuit 99 includes the first impedor 991 and second
Impedor 992.One end of described first impedor 991 connects half-wave voltage signal node N0, and described the
The other end of one impedor 991 connects one end of described second impedor 992 and is suitable to produce control
Voltage Vctr, the other end ground connection of described second impedor 992.By described first impedor 991
Dividing potential drop with described second impedor 992, it is achieved the voltage VH of described half-wave voltage signal node N0 is adopted
Sample, it is thus achieved that described control voltage Vctr.It should be noted that described impedor 991 and described second
Impedor 992 can be pure resistance element, it is also possible to for presenting other electrical equipments of impedance operator,
This is not construed as limiting by the present invention.
Described reference voltage adjustment unit 953 include clamping unit the 9531, second voltage comparator 9532,
Select unit 9533 and adder 9534.
Described clamping unit 9531 is suitable to described control end CTR is carried out clamper, i.e. at described control end
When the magnitude of voltage of the voltage Vq of CTR is more than described first magnitude of voltage U1, by described control end CTR's
The magnitude of voltage of voltage Vq is limited to described first magnitude of voltage U1.
Described second voltage comparator 9532 is suitable to 0V voltage and the voltage Vq of described control end CTR
Compare to produce comparative level Vcomp, electric more than 0V at the voltage Vq of described control end CTR
Produce the first comparative level during pressure, otherwise produce the second comparative level.Specifically, described second voltage ratio
The first input end of relatively device 9532 connects described control end CTR, described second voltage comparator 9532
Second input end grounding.It should be noted that in the present embodiment, described second voltage comparator 9532
The anode that first input end is described second voltage comparator 9532, described second voltage comparator 9532
The negative terminal that the second input is described second voltage comparator 9532.In other embodiments, described
The first input end of two voltage comparators 9532 can also be the negative terminal of described second voltage comparator 9532,
Second input of described second voltage comparator 9532 should be described second voltage comparator 9532 mutually
Anode, this is not construed as limiting by the present invention.
Described selection unit 9533 is suitable to receive the first reference voltage VR1, the electricity of described control end CTR
The comparative level Vcomp that pressure Vq and described second voltage comparator 9532 produce, described receiving
The voltage Vq selecting described control end CTR during the first comparative level exports, and is receiving described second ratio
Relatively select described first reference voltage VR1 output, the magnitude of voltage of described first reference voltage VR1 during level
Equal to described first magnitude of voltage U1.
Described adder 9534 is suitable to superposition the second reference voltage VR2 and described selection unit 9533 exports
Voltage to produce described peakedness ratio relatively reference voltage V ref, the magnitude of voltage of described second reference voltage VR2
Equal to described third voltage value U3.Described adder 9534 can use operational amplifier to realize, ability
Field technique personnel know the physical circuit of described adder 9534, do not repeat them here.
Described first reference voltage VR1 and described second reference voltage VR2 can be provided by external circuit,
Can also be provided by the internal source voltage of described control circuit 953.In the present embodiment, described control electricity
Road 953 also includes the first voltage source 9535 and the second voltage source 9536.Described first voltage source 9535
Anode is suitable to export described first reference voltage VR1, the negativing ending grounding of described first voltage source 9535；Institute
The anode stating the second voltage source 9536 is suitable to export described second reference voltage VR2, described second voltage source
The negativing ending grounding of 8536.
Figure 10 is the control voltage Vctr of the embodiment of the present invention, to control the voltage Vq of end CTR, comparison electric
Flat Vcomp, the second reference voltage VR2 and peakedness ratio are compared with the time dependent waveform of reference voltage V ref
Schematic diagram, below in conjunction with Fig. 9 and Figure 10 work to the reference voltage adjustment unit 953 of the embodiment of the present invention
Illustrate as principle.
Described control end CTR receives the control voltage Vctr of described sample circuit 89 output, described control
The waveform of voltage Vctr is half-wave.Along with described control voltage Vctr constantly increases, described control end CTR
Voltage Vq constantly increase.When the magnitude of voltage of described control voltage Vctr exceedes described first magnitude of voltage U1
Time, described clamping unit 9531 carries out clamper to described control end CTR, by described control end CTR's
The magnitude of voltage of voltage Vq is limited in described first magnitude of voltage U1.
Voltage Vq and the 0V voltage of described control end CTR are carried out by described second voltage comparator 9532
Relatively, when the voltage Vq of described control end CTR is more than 0V, described comparative level Vcomp is the
One comparative level comp1；When the voltage Vq of described control end CTR is equal to 0V, described comparative level
Vcomp is the second comparative level comp2.Described first comparative level comp1 is high level, described
Two comparative level comp2 are low level.
Described selection unit 9533 exports described control end when receiving described first comparative level comp1
The voltage Vq of CTR, described adder 9534 is by the voltage Vq and described second of described control end CTR
Reference voltage VR2 is added；Described selection unit 9533 is receiving described second comparative level comp2
Time export described first reference voltage VR1, described adder 9534 is by described first reference voltage VR1
It is added with described second reference voltage VR2.
The embodiment of the present invention provides the particular circuit configurations of a kind of described clamping unit 9531, such as Figure 11 institute
Show.Described clamping unit 9531 includes Zener diode D0, the burning voltage of described Zener diode D0
Magnitude of voltage equal to described first magnitude of voltage U1.Specifically, the negative electrode of described Zener diode D0 connects
Described control end CTR, the plus earth of described Zener diode D0.Electricity as described control end CTR
When pressure value is more than described first magnitude of voltage U1, described Zener diode D0 is breakdown, described control end CTR
Magnitude of voltage Vq i.e. equal to the burning voltage of described Zener diode D0.Described Zener diode D0's
Simple in construction, saves the area of described control circuit 95.
The embodiment of the present invention provides the particular circuit configurations of another kind of described clamping unit 9531, such as Figure 12
Shown in.Described clamping unit 9531 includes transistor Q0 and operational amplifier A 0, wherein, described crystal
The electrode that controls of pipe Q0 connects the outfan of described operational amplifier A 0, the first of described transistor Q0
Electrode connects described control end CTR and the inverting input of described operational amplifier A 0, described transistor
The second electrode ground connection of Q0, the in-phase input end of described operational amplifier A 0 is suitable to input described first ginseng
Examine voltage VR1.
When the magnitude of voltage of described control end CTR is more than described first magnitude of voltage U1, described operation amplifier
The anti-phase input terminal voltage of device A0 is higher than its in-phase input end voltage, produces and amplifies signal；Described amplification is believed
Number control described crystal Q0 conducting, described control end CTR is shunted, makes institute by described transistor Q0
State the voltage decline controlling end CTR, the magnitude of voltage of the voltage Vq of described control end CTR is limited in institute
State the first magnitude of voltage U1.
Owing to described operational amplifier A 0 has higher gain, when the magnitude of voltage of described control end CTR
During more than described first magnitude of voltage U1, described operational amplifier A 0 can output control signals to rapidly
The control electrode of described transistor Q0, controls described transistor Q0 conducting, to described control end CTR
Shunt, thus rapidly described control end CTR is carried out clamper, improve described peak value benchmark
The precision of voltage Vref.
In the present embodiment, described transistor Q0 is PNP triode: the base stage of described PNP triode
For the control electrode of described transistor Q0, the transmitting the most described transistor Q0's of described PNP triode
First electrode, second electrode of the current collection the most described transistor Q0 of described PNP triode.Due to institute
State PNP triode and there is Current amplifier function, it is possible to the control signal inputted its base stage rapidly is made
Response, carries out clamper to described control end CTR rapidly.
The embodiment of the present invention provides the particular circuit configurations of another kind of described clamping unit 9531, such as Figure 13
Shown in.Described clamping unit 9531 includes transistor Q0' and operational amplifier A 0', wherein, described crystal
The electrode that controls of pipe Q0' connects the outfan of described operational amplifier A 0', the first of described transistor Q0'
Electrode connects described control end CTR and the inverting input of described operational amplifier A 0', described transistor
The second electrode ground connection of Q0', the in-phase input end of described operational amplifier A 0' is suitable to input described first ginseng
Examine voltage VR1.
In the present embodiment, described transistor Q0' is PMOS: the grid of described PMOS is institute
State the control electrode of transistor Q0', first electrode that drain electrode is described transistor Q0' of described PMOS,
The source electrode of described PMOS is second electrode of described transistor Q0'.
The embodiment of the present invention provides the particular circuit configurations of a kind of described selection unit 9533, such as Figure 14 institute
Show.Described selection unit 9533 includes the first switch K1 and second switch K2.Specifically, described first
The electrode that controls of switch K1 connects the control electrode of described second switch K2 and described second voltage comparator
The outfan of 9532, is i.e. suitable to input described comparative level Vcomp, the first of described first switch K1
End connects described control end CTR, is i.e. suitable to input the voltage Vq of described control end CTR, and described first
Second end of switch K1 connects first end of described second switch K2 and as described selection unit 9533
Outfan Out1, i.e. connect described adder 9534.Second end of described second switch K2 is suitable to defeated
Enter described first reference voltage VR1.
Described first switch K1 turns on when receiving described first comparative level comp1, is receiving
Disconnect during described second comparative level comp2；Described second switch K2 compares receiving described second
Turn on during level comp2, disconnect when receiving described first comparative level comp1.
It should be noted that described first switch K1 and described second switch K2 can be MOS switch.
Such as, described first switch K1 is NMOS tube, and described second switch K2 is PMOS.Described
The grid of NMOS tube is the control electrode of described first switch K1, and the drain electrode of described NMOS tube is institute
Stating first end of the first switch K1, the source electrode of described NMOS tube is second end of described first switch K1；
The grid of described PMOS is the control electrode of described second switch K2, the drain electrode of described PMOS
For first end of described second switch K2, the source electrode of described PMOS is the of described second switch K2
Two ends.Described first switch K1 and described second switch K2 can also have the device of switching function for other
Part or integrated circuit, this is not construed as limiting by the present invention.
In embodiments of the present invention and embodiment, it is all to illustrate as a example by inverse-excitation type switch power-supply.
It practice, the control circuit highly versatile of the Switching Power Supply of present invention offer, it is applicable to different types of
Switching Power Supply: can apply to (the such as inverse-excitation type switch power-supply shown in Fig. 8) in isolation type switching power supply,
Can also be applied in non-isolated Switching Power Supply.
Figure 15 is the structural representation of the another kind of Switching Power Supply that the embodiment of the present invention provides, described switch electricity
Source is step down switching regulator.Specifically, described Switching Power Supply includes rectifier bridge 60a, inductance 62a, opens
Close transistor 63a, sampling resistor 64a, control circuit 65a, commutation diode 66a, secondary filter capacitor
67a, valley fill circuit 68a and sample circuit 69a, wherein, described control circuit 65a includes peak electricity
Stream test side CS, feedback end FB, drive end DRV, the first voltage comparator 65a1, pulse width are adjusted
Unit 65a2 processed, control end CTR and reference voltage adjustment unit 65a3.Described sample circuit 69a
The description to Fig. 6, people in the art is referred to concrete structure and the function of described control circuit 65a
Member knows the specific works principle of step down switching regulator, does not repeats them here.
Figure 16 is the structural representation of the another kind of Switching Power Supply that the embodiment of the present invention provides, described switch electricity
Source is buck boost switcher power supply, including rectifier bridge 60b, inductance 62b, switching transistor 63b, sampling
Resistance 64b, control circuit 65b, commutation diode 66b, secondary filter capacitor 67b, valley fill circuit 68b
And sample circuit 69b, wherein, described control circuit 65b includes peak current detection end CS, feedback
End FB, drive end DRV, the first voltage comparator 65b1, pwm unit 65b2, control
End CTR and reference voltage adjustment unit 65b3.Described sample circuit 69b and described control circuit 65b
Concrete structure and function refer to the description to Fig. 6, those skilled in the art know buck boost switcher
The specific works principle of power supply, does not repeats them here.
In sum, the Switching Power Supply of technical solution of the present invention offer and control circuit thereof, by filling out paddy
The half-wave voltage signal node of circuit is sampled, it is thus achieved that control voltage, and by reference voltage adjustment unit according to
Described control voltage changes peakedness ratio relatively reference voltage, makes the input power of described Switching Power Supply follow described
The input voltage change of Switching Power Supply, to eliminate the spike of AC input current, reduces described Switching Power Supply
Total harmonic distortion.
Although present disclosure is as above, but the present invention is not limited to this.Any those skilled in the art,
Without departing from the spirit and scope of the present invention, all can make various changes or modifications, therefore the guarantor of the present invention
The scope of protecting should be as the criterion with claim limited range.
Claims (10)
1. a control circuit for Switching Power Supply, including peak current detection end, feedback end, drive end, first
Voltage comparator and pwm unit, it is characterised in that also include:
Control end, be suitable to receive control voltage；
Reference voltage adjustment unit, is suitable to according to described control voltage generation peakedness ratio relatively reference voltage:
When magnitude of voltage at described control voltage is equal to 0V or is more than the first magnitude of voltage, described peakedness ratio is relatively
The magnitude of voltage of reference voltage is the second magnitude of voltage；
When the magnitude of voltage of described control voltage is more than 0V and the most described first magnitude of voltage, described peak value
The magnitude of voltage of benchmark voltage is equal to the magnitude of voltage sum of third voltage value with described control voltage, described
Third voltage value and described first magnitude of voltage sum are equal to described second magnitude of voltage；
Described reference voltage adjustment unit includes:
Clamping unit, is suitable to described control when the magnitude of voltage of described control end is more than described first magnitude of voltage
The magnitude of voltage of end processed is limited to described first magnitude of voltage；
Second voltage comparator, is suitable to compare the voltage of 0V voltage and described control end to produce ratio
Relatively level, produces the first comparative level when the voltage of described control end is more than 0V voltage, otherwise produces the
Two comparative levels；
Select unit, be suitable to receive the first reference voltage, the voltage of described control end and described second electricity
The comparative level that pressure comparator produces, selects described control end when receiving described first comparative level
Voltage exports, and selects described first reference voltage output when receiving described second comparative level, described
The magnitude of voltage of the first reference voltage is equal to described first magnitude of voltage；
Adder, the voltage being suitable to superposition the second reference voltage and the output of described selection unit is described to produce
Peakedness ratio relatively reference voltage, the magnitude of voltage of described second reference voltage is equal to described third voltage value.
2. the control circuit of Switching Power Supply as claimed in claim 1, it is characterised in that described clamping unit bag
Including Zener diode, the magnitude of voltage of the burning voltage of described Zener diode is equal to described first magnitude of voltage；
The negative electrode of described Zener diode connects described control end, the plus earth of described Zener diode.
3. the control circuit of Switching Power Supply as claimed in claim 1, it is characterised in that described clamping unit bag
Include transistor and operational amplifier；
The electrode that controls of described transistor connects the outfan of described operational amplifier, the of described transistor
One electrode connects described control end and the inverting input of described operational amplifier, the second of described transistor
Electrode ground connection；
The in-phase input end of described operational amplifier is suitable to input described first reference voltage.
4. the control circuit of Switching Power Supply as claimed in claim 3, it is characterised in that described transistor is PNP
Audion；
The base stage of described PNP triode is the control electrode of described transistor, sending out of described PNP triode
Emitter-base bandgap grading is the first electrode of described transistor, the of the most described transistor of current collection of described PNP triode
Two electrodes.
5. the control circuit of Switching Power Supply as claimed in claim 3, it is characterised in that described transistor is
PMOS；
The grid of described PMOS is the control electrode of described transistor, and the drain electrode of described PMOS is
First electrode of described transistor, the source electrode of described PMOS is the second electrode of described transistor.
6. the control circuit of Switching Power Supply as claimed in claim 2, it is characterised in that described selection unit bag
Include the first switch and second switch；
The electrode that controls of described first switch connects the control electrode of described second switch and described second voltage
The outfan of comparator, the first end of described first switch connects described control end, described first switch
Second end connects the first end of described second switch and as the outfan of described selection unit；
Second end of described second switch is suitable to input described first reference voltage；
Described first switch turns on when described selection unit receives described first comparative level, described
Unit is selected to disconnect when receiving described second comparative level；
Described second switch disconnects when described selection unit receives described first comparative level, described
Conducting when selecting unit to receive described second comparative level.
7. the control circuit of the Switching Power Supply as described in any one of claim 1 to 6, it is characterised in that also wrap
Include:
First voltage source, is adapted to provide for described first reference voltage；
Second voltage source, is adapted to provide for described second reference voltage.
8. a Switching Power Supply, including rectifier bridge, valley fill circuit and switching transistor, it is characterised in that also
Including:
The control circuit of the Switching Power Supply described in any one of claim 1 to 7；
Sample circuit, the voltage being suitable to the half-wave voltage signal node to described valley fill circuit samples to produce
Described control voltage.
9. Switching Power Supply as claimed in claim 8, it is characterised in that described sample circuit includes the first impedance
Element and the second impedor；
Described first impedor one end connects described half-wave voltage signal node, described first impedor
The other end connects described second impedor one end and is suitable to produce described control voltage；
Described second impedor other end ground connection.
10. Switching Power Supply as claimed in claim 8, it is characterised in that described Switching Power Supply is flyback switching
Power supply, step down switching regulator or buck boost switcher power supply.
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| CN107957514B (en) * | 2016-10-14 | 2020-12-04 | 佛山市顺德区美的电热电器制造有限公司 | Zero-crossing detection device and method and electric appliance |
| CN109068444B (en) * | 2018-08-17 | 2020-07-31 | 江苏大学 | Single-stage non-isolated electrolytic capacitor L ED driving power supply and switching method |
| CN109600060B (en) * | 2018-12-27 | 2021-01-05 | 广州金升阳科技有限公司 | Improved flyback power supply circuit |
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| CN201122904Y (en) * | 2007-11-29 | 2008-09-24 | 上海辰蕊微电子科技有限公司 | Summit current operated electric voltage feed forward circuit in switch power source |
| CN101951177B (en) * | 2010-09-06 | 2014-05-07 | Bcd半导体制造有限公司 | Switching power supply system and switching power supply control circuit |
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Effective date of registration: 20210714 Address after: 201100 room 803, 8 / F, building 5, No. 7001, Zhongchun Road, Minhang District, Shanghai Patentee after: SHANGHAI LUMIXESS LIGHTING TECHNOLOGY Co. Address before: 213164 room 210, block C, Tianrun science and technology building, Changzhou science and Education City, No. 801, middle Changwu Road, Wujin District, Changzhou City, Jiangsu Province Patentee before: CHANGZHOU LUMIXESS TECHNOLOGY Co.,Ltd. |
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