CN106208668A - Pfc circuit, PFC control circuit and Switching Power Supply - Google Patents
Pfc circuit, PFC control circuit and Switching Power Supply Download PDFInfo
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- CN106208668A CN106208668A CN201610808084.0A CN201610808084A CN106208668A CN 106208668 A CN106208668 A CN 106208668A CN 201610808084 A CN201610808084 A CN 201610808084A CN 106208668 A CN106208668 A CN 106208668A
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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
- H02M1/4225—Arrangements for improving power factor of AC input using a non-isolated boost converter
-
- 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
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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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P80/00—Climate change mitigation technologies for sector-wide applications
- Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier
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- Power Engineering (AREA)
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- Dc-Dc Converters (AREA)
Abstract
The present invention relates to field of switch power, be specifically related to a kind of Switching Power Supply reducing the pfc circuit of output capacitance, PFC control circuit and applying this PFC control circuit.With regard to a kind of pfc circuit provided by the present invention, including PFC control chip, wherein it is integrated with feedback control circuit, receives input sample voltage and the output sampled voltage of output detection circuit of input detecting circuit, and export control signal to carry out the mode of operation control of voltage conversion circuit；PFC control chip has reference voltage end, it is characterised in that: also including waveform shaping circuit, for blocking the crest of input sample signal, waveform shaping circuit is external between reference voltage end and the ground of PFC control chip.Compared with prior art, circuit is simpler, and cost is lower, it is easier to realize for the present invention.
Description
Technical field
The present invention relates to field of switch power, be specifically related to a kind of reduce the pfc circuit of output capacitance, PFC controls electricity
Road and apply the Switching Power Supply of this PFC control circuit.
Background technology
Along with the development of electronic technology, the requirement to Switching Power Supply is more and more higher, it is desirable to Switching Power Supply has the higher longevity
Life, less volume and lower cost.It is known that the life-span of current electrolysis electric capacity only have thousand of hours to up to ten thousand time,
The high temperature lower life-span can be shorter.Electrochemical capacitor is widely used in AC-DC Switching Power Supply, and electrochemical capacitor is to determine the Switching Power Supply longevity
Order topmost device.Electrochemical capacitor has unit volume capacity big, the advantage of low cost.Other electric capacity such as thin-film electro at present
Appearance, ceramic condenser etc. also cannot substitute electrochemical capacitor completely, the problem being the most just because volume and cost.So wanting to substitute
Electrochemical capacitor, is necessary for there is special control in circuit, reduces the requirement to output capacitance capacity.
The essence of pfc circuit is through certain control device, allows the waveform of input current follow the ripple of input voltage
Deformation.The most conventional PFC control method has two kinds.One is that permanent conducting controls, according to formulaWherein lead
Logical time Ton and PFC inductance sensibility reciprocal L is fixing, it is possible to allow input current change according to input voltage.Another kind is detection
Input voltage and PFC inductive current, allow inductive current follow the change of input voltage, here referred to as inspection by feedback control
Observing and controlling system.Using, than more typically, the chip detecting control on the market is L6562, and this chip operation is in critical conduction mode.Pfc circuit
Input power followed by input voltage change, and at input voltage crest, input power is maximum, input power at zero passage
Minimum.As a example by input mean power 20W, when input voltage and input current are all synchronous power frequency sine wave, half
In individual power frequency period, Instantaneous input power waveform is as it is shown in figure 1, at 1/4 power frequency period, the instantaneous power of input is maximum, has
40W.Owing to input power fluctuation is big, so being accomplished by bigger output storage capacitor, the most excessive output voltage ripple may
Some device excessive pressure damages in circuit can be caused, so can not at will reduce output capacitance in traditional pfc circuit.
In order to reduce output capacitance it is necessary to limit the fluctuation of input power, in fact seek to limit the fluctuation of input current.
The waveform changing input current can make PF value decline, and can be rolled over PF value and output capacitance by certain method
In.Such as the method in application number 201310304212.4, the PFC in this patent controls substantially to use inspection control methods.
By the method for signal syntheses, the sinusoidal signal of one 90 degree of phase contrast of superposition on the input sine voltage signal detected.
Allow PFC inductive current follow this and synthesize the signal obtained.At input voltage crest, limit the amplitude of input current, reduce
The peak value of instantaneous power, such that it is able to reduce output capacitance.The method using signal syntheses due to this patent, except needing
The detection wanting common controls outside class PFC control chip, and multiple operation amplifier used by phase-shift circuit to be had and computing circuit
Device, circuit is complicated, and cost is high.
Summary of the invention
The present invention solves the baroque problem of above-mentioned control circuit, it is provided that a kind of pfc circuit so that in same output
Under ripple, using the present invention just can use less output capacitance, and control circuit is simple, cost is lower, the most practical.
Corresponding to this, the present invention, during solving above-mentioned technical problem, also provides for based on this pfc circuit further
PFC control circuit and Switching Power Supply based on this PFC control circuit, so that control circuit simple in construction, cost is lower, easily
Practical.
With regard to a kind of pfc circuit provided by the present invention, including PFC control chip, wherein it is integrated with feedback control circuit, connects
Receive the input sample voltage of input detecting circuit and the output sampled voltage of output detection circuit, and export control signal and carry out
The mode of operation of voltage conversion circuit controls；PFC control chip has reference voltage end, it is characterised in that: also include that waveform is whole
Shape circuit, for blocking the crest of input sample signal, waveform shaping circuit be external in the reference voltage end of PFC control chip with
Between ground.
Preferably, described waveform shaping circuit, including a Zener diode, the negative electrode of Zener diode controls with PFC
The reference voltage end of chip is connected, the plus earth of Zener diode.
Preferably, described waveform shaping circuit, including the second Zener diode, the second diode, the 3rd diode, the 3rd
Electric capacity, the 6th resistance, the 7th resistance；3rd diode anode is used for being connected with the bus after rectification, the negative electrode of the 3rd diode
By the 3rd capacity earth, after the 6th resistance and the 7th resistant series, it is parallel to the 3rd electric capacity two ends, the 6th resistance and the 7th electricity
Junction point and the anode of the second Zener diode between resistance are connected, the second Zener diode negative electrode and the negative electrode of the second diode
Being connected, the anode of the second diode is connected with the reference voltage end of PFC control chip.
Preferably, described feedback control circuit, including operational amplifier, loop compensation circuit, multiplier, comparator, time
Clock circuit and d type flip flop, the input anode of operational amplifier is connected with reference voltage, and the input negative terminal of described operational amplifier is made
The second input for feedback control circuit；Loop compensation circuit is connected to outfan and the input negative terminal of described operational amplifier
Between；The first input end of multiplier is as the first input end of feedback control circuit, the second input of multiplier and computing
The outfan of amplifying circuit is connected, and the outfan of multiplier is connected with the input negative terminal of comparator, and the input anode of comparator is made
For the 3rd input of feedback control circuit, the output of comparator is connected with the R input of d type flip flop, the output of clock circuit
End is connected with the S input of d type flip flop, and the outfan of d type flip flop is as the outfan of feedback control circuit.
The present invention also provides for a kind of PFC control circuit, is connected between rectification circuit and voltage conversion circuit, including input
Testing circuit, output detection circuit and above-mentioned pfc circuit, input detecting circuit, the input voltage after sampling rectification generates defeated
Enter sampled signal, it is provided that to PFC control circuit；Output detection circuit, the voltage of detection voltage conversion circuit output, control for PFC
Circuit processed provides output sampled voltage.
Preferably, described input detecting circuit, it is parallel between the bus after rectification and ground, in order to detect the mother after rectification
Line voltage, provides reference voltage waveform for feedback control circuit.
Preferably, described input detecting circuit, including the first resistance and the second resistance, the first resistance and the second resistant series
Connecting, the junction point of the first resistance and the second resistance is as the outfan of input detecting circuit.
Preferably, described output detection circuit, it is parallel between the output voltage of PFC control circuit and ground, in order to detect
The voltage of voltage conversion circuit output, provides output sampled voltage for feedback control circuit.
Preferably, described output detection circuit, including the 3rd resistance and the 4th resistance, the 3rd resistance and the 4th resistant series
Connecting, the junction point of the 3rd resistance and the 4th resistance is as the outfan of output detection circuit.
The present invention reoffers a kind of Switching Power Supply, controls electricity including rectification circuit, voltage conversion circuit and above-mentioned PFC
Road, PFC control circuit is connected between rectification circuit and voltage conversion circuit, and voltage conversion circuit is BOOST booster circuit, bag
Including inductance, N-MOS pipe, the first diode, the second electric capacity and the 5th resistance, one end of inductance is as the first of voltage conversion circuit
Input；The drain electrode of the other end of inductance and N-MOS pipe and the anode of the first diode are connected, and the source electrode of N-MOS pipe passes through the
Five resistance eutral groundings, the source electrode of N-MOS pipe is also as the second outfan of voltage conversion circuit, and the grid of N-MOS pipe is as voltage
Second input of change-over circuit；The negative electrode of the first diode passes through the second capacity earth, the also conduct of the negative electrode of the first diode
First outfan of voltage conversion circuit.
When applying the present invention in switching power circuit, form a kind of new Switching Power Supply, including AC-DC power circuit
And PFC control circuit, wherein, AC-DC power circuit includes rectification circuit and voltage conversion circuit, and PFC control circuit includes defeated
Enter testing circuit, waveform shaping circuit, output detection circuit and feedback control circuit.The input of described rectification circuit and friendship
Stream city is electrically connected, the first input end of described voltage conversion circuit, input and the described rectified current of described input detecting circuit
The outfan on road is connected, and the outfan of described input detecting circuit is whole with the first input end of described feedback control circuit and waveform
The input of shape circuit is connected, the first outfan of described voltage conversion circuit and the input phase of described output detection circuit
Even, the outfan of described output detection circuit is connected with the second input of described feedback control circuit, described voltage conversion electricity
Second outfan on road is connected with the 3rd input of described feedback control circuit, the first outfan of described feedback control circuit
It is connected with the second input of described voltage conversion circuit.
Described waveform shaping circuit includes a Zener diode, the negative electrode of described Zener diode and described waveform shaping electricity
The input on road is connected, the plus earth of described Zener diode.
Described input detecting circuit is parallel to after including the first resistance and the second resistance, the first resistance and the second resistant series
Between input and the ground of described input detecting circuit, the junction point of the first resistance and the second resistance is as described input detection
The outfan of circuit.
Described output detection circuit includes the 3rd resistance and the 4th resistance, is parallel to after the 3rd resistance and the 4th resistant series
Between input and the ground of described output detection circuit, the junction point of the 3rd resistance and the 4th resistance is as described output detections electricity
The outfan on road.
Described feedback control circuit includes operational amplifier, loop compensation circuit, multiplier, comparator, clock circuit and D
Trigger.The input anode of described operational amplifier is connected with reference voltage, and the input negative terminal of described operational amplifier is as institute
Stating the second input of feedback control circuit, described loop compensation circuit is connected to outfan and the input of described operational amplifier
Between negative terminal.The first input end of described multiplier is connected with the first input end of described feedback control circuit, described multiplier
The second input be connected with the outfan of described operational amplification circuit, the outfan of described multiplier is defeated with described comparator
Entering negative terminal to be connected, the input anode of described comparator is connected with the 3rd input of described feedback control circuit, described comparator
Output be connected with the R input of described d type flip flop, the S input phase of the outfan of described clock circuit and described d type flip flop
Even, the outfan of described d type flip flop is connected with the first outfan of described feedback control circuit.
Described voltage conversion circuit includes an inductance, a switching tube, a diode, an electric capacity and the 5th electricity
Resistance.
Compared with prior art, circuit is simpler, and cost is lower, it is easier to realize for the present invention.
Accompanying drawing explanation
Fig. 1 is common PFC input power oscillogram；
Fig. 2 is the circuit former road figure that the PFC control circuit of first embodiment of the invention is applied to main power circuit；
Fig. 3-1 is the voltage oscillogram of the node A of the PFC control circuit of first embodiment of the invention；
Fig. 3-2 is the oscillogram of the input current of the PFC control circuit of first embodiment of the invention；
Fig. 4 is the harmonic component figure of the input current of the PFC control circuit of first embodiment of the invention；
Fig. 5 is the PFC control circuit comparison diagram with the input power of common PFC control of first embodiment of the invention；
Fig. 6 is the PFC control circuit contrast with the output voltage ripple of common PFC control of first embodiment of the invention
Figure；
Fig. 7 be first embodiment of the invention PFC control circuit in the voltage oscillogram of A node；
Fig. 8 is the circuit former road figure of the PFC control circuit of second embodiment of the invention；
Fig. 9-1 be second embodiment of the invention PFC control circuit in the voltage oscillogram of A node；
Fig. 9-2 be second embodiment of the invention PFC control circuit in oscillogram after A node normalization.
Detailed description of the invention
The PFC control chip using detection to control, generally includes error amplifier, loop compensation circuit, multiplier, compares
Device, clock circuit and d type flip flop, and there is input voltage measurement end, output voltage test side, current detecting end and drive output
End.The function of input test side is the busbar voltage after detection rectification, and the function of output detections end is detection PFC main power circuit
Output voltage, the cut-off frequency of loop compensation circuit that usual PFC controls is the lowest, and loop is very slow, output voltage test side
Voltage signal becomes the error signal that ripple is the least after error amplifier, can be approximately DC voltage.This error signal with
With load change, loading the heaviest, error voltage is the highest.The voltage signal of error signal and input test side is as multiplier
Input, obtain current reference signal after being multiplied, the waveform of this signal is consistent with the waveform of input voltage, control input current with
With current reference signal, just reach the effect of PFC.
And control input current follow reference current signal be achieved in that main power topology as a example by BOOST circuit,
Drive output controls the conducting of BOOST contactor pipe, and the inductance of BOOST circuit is excitatory, and inductive current rises, current detecting
The current signal of end detection inductance, current signal compares through comparator with current reference signal, when current signal is than electric current base
Just turning off BOOST contactor pipe during calibration signal height, clock circuit controls the switching frequency of BOOST contactor pipe, so
The waveform of the peak point current envelope of BOOST circuit inductance is exactly the waveform of current reference signal, and the peak of BOOST circuit inductance
Value electric current is directly proportional to input current, thus has reached the effect that PFC controls.
In the present invention, waveform shaping circuit is added, thus it is possible to vary PFC control chip input voltage measurement end, thus
Reach the effect of input current, the power distribution in half power frequency period can be redistributed, reduce the peak value of input power,
Output voltage ripple is diminished, and the impact of PF value is the least.
Below in conjunction with accompanying drawing, principle and the embodiment of invention are described in detail.
First embodiment
The first embodiment of the present invention is as shown in Figure 2.A kind of Switching Power Supply, controls electricity including AC-DC power circuit and PFC
Road, wherein AC-DC power circuit includes BD1 rectification circuit and voltage conversion circuit 101, and voltage conversion circuit 101 is also main merit
Rate circuit, PFC control circuit is located between rectification circuit and voltage conversion circuit；PFC control circuit includes input detecting circuit
102, waveform shaping circuit 103, output detection circuit 104 and feedback control circuit 105, input detecting circuit 102, detect whole
Busbar voltage after stream, provides reference voltage waveform for feedback control circuit；Output detection circuit 104, detection voltage conversion electricity
The voltage of road output, provides output sampled voltage for feedback control circuit；Feedback control circuit, receives input detecting circuit 102
Reference voltage waveform and the output sampled voltage of output detection circuit 104, and export control signal to carry out voltage conversion electricity
The mode of operation on road 101 controls.
The input of rectification circuit BD1 is connected with electric main, the first input end of voltage conversion circuit 101, input inspection
The input of slowdown monitoring circuit 102 is connected with the outfan of rectification circuit BD1, the outfan of input detecting circuit 102 and feedback control
The first input end of circuit 105 is connected with the input of waveform shaping circuit 103, the first outfan of voltage conversion circuit 101
It is connected with the input of output detection circuit 104, the outfan of output detection circuit 104 and the second of feedback control circuit 105
Input is connected, and the second outfan of voltage conversion circuit 101 is connected with the 3rd input of feedback control circuit 105, feedback
First outfan of control circuit 105 is connected with the second input of voltage conversion circuit 101.
Wherein, feedback control circuit 105 can use integrated PFC control chip, and PFC control chip has reference voltage
End.In other words, PFC control circuit includes PFC control chip and input detecting circuit 102, waveform shaping circuit 103, output inspection
Slowdown monitoring circuit 104 peripheral circuit such as grade, PFC control chip and waveform shaping circuit 103 form pfc circuit, input detecting circuit 102,
Output detection circuit 104 and pfc circuit composition PFC control circuit.
Waveform shaping circuit 103 includes Zener diode Z1, and the negative electrode of Zener diode Z1 is as waveform shaping circuit 103
Input, be connected with the reference voltage end of PFC control chip；The plus earth of Zener diode Z1.Reference voltage end is also
Exit at marked A point in figure, hereinafter referred to as A point end.
Input detecting circuit 102 include resistance R1 and resistance R2, resistance R1 connect with resistance R2 after ground connection, resistance R1 and electricity
The junction point of resistance R2 is as the outfan of input detecting circuit 102.And choose the junction point of resistance R1 and resistance R2 as node
A, to launch detailed circuit analysis.Node A can lead to external pin end, the bringing-out of node A from PFC control chip
It is A point end.In the present embodiment, A point end is the MULT pin of PFC control chip, and the Chinese of MULT pin is reference
Voltage end.In other embodiments, same or analogous functional pin, when selecting the PFC control chip of different manufacturers, pin
The definition of title may be different, are not limited with pin name.
Output detection circuit 104 include resistance R3 and resistance R4, resistance R3 connect with resistance R4 after ground connection, resistance R3 and electricity
The junction point of resistance R4 is as the outfan of output detection circuit 104.
Feedback control circuit 105 includes operational amplifier U1, loop compensation circuit, multiplier U4, comparator U2, clock electricity
Road and d type flip flop U3.The input anode of operational amplifier U1 is connected with reference voltage REF, the input negative terminal of operational amplifier U1
As the second input of feedback control circuit 105, loop compensation circuit is connected to outfan and the input of operational amplifier U1
Between negative terminal.Choose the outfan of operational amplifier U1 as node B, to launch detailed circuit analysis.The of multiplier U4
One input is as the first input end of feedback control circuit 105, second input of multiplier U4 and operational amplification circuit U1
Outfan be connected, the outfan of multiplier U4 is connected with the input negative terminal of comparator U2, the input anode conduct of comparator U2
3rd input of feedback control circuit 105, the output of comparator U2 is connected with the R input of d type flip flop U3, clock circuit
Outfan is connected with the S input of d type flip flop U3, and the outfan of d type flip flop U3 is as the first output of feedback control circuit 105
End.
Voltage conversion circuit 101 includes inductance L1, N-MOS pipe TR1, diode D1, electric capacity C2 and resistance R5.Inductance L1's
One end as the first input end of voltage conversion circuit, the drain electrode of the inductance L1 other end and N-MOS pipe TR1 and the sun of diode D1
The most connected, the source electrode of N-MOS pipe TR1 passes through resistance R5 ground connection, and the source electrode of N-MOS pipe TR1 is also as voltage conversion circuit 101
Second outfan, the grid of N-MOS pipe TR1 is as the second input of voltage conversion circuit 101, the negative electrode of diode D1 and electricity
Holding one end of C2, the negative electrode of diode D1 is also as the first outfan of voltage conversion circuit 101, another termination of electric capacity C2
Ground.
In the present embodiment, the major function of each several part is as follows.Voltage conversion circuit 105 is BOOST booster circuit.Resistance R1
With resistance R2 input voltage after rectification of sampling, the effect of Zener diode Z1 is that the crest of input sample signal is cut
Disconnected.R3 and R4 be used for sampling and outputting voltage, loop compensation circuit cross-over frequency arrange ratio is relatively low, be arranged on below power frequency,
For filtering the working frequency ripple wave of output, then the output voltage of operational amplifier U1 just can approximate and regard DC voltage as.This is straight
Input sample voltage after flowing voltage and being shaped, after multiplier U4 is multiplied, obtains peak point current baseline threshold.R5 is used for
The electric current of detection inductance L1, allows the current signal of inductance L1 compare with peak point current baseline threshold, when the peak value of inductance L1
During current ratio peak point current baseline threshold height, allow N-MOS pipe TR1 turn off, thus allow the peak point current of inductance follow peak point current
The change of baseline threshold, is finally reached the purpose controlling input voltage and input current change.General detection controls the PFC of class and controls core
Sheet, all passes through the method and controls the electric current of inductance L1.
After adding waveform shaping circuit 103, the voltage waveform of node A as shown in figure 3-1, input current IinWaveform meeting
Follow the voltage waveform of node A, input current IinWaveform is as shown in figure 3-2.The voltage of derivation node A is by waveform shaping electricity below
After road 103 changes, the effect brought.The function of voltage assuming node A is VA=f (t).Generally in pfc circuit, loop is mended
The cross-over frequency repaid all ratios are relatively low, for filtering the fluctuation of power, so the voltage V of node BBCan be approximately considered is that ripple is the least
DC voltage.It is not difficult to obtain, inductance L1 peak current value Ipeak=VA*VB/R5.In existing PFC control chip, Ke Yirang
Voltage conversion circuit is operated in critical conduction mode, then input current Iin=1/2*Ipeak.Can obtain in conjunction with above-mentioned formula, Iin=
VA*VB/(2*R5), in the case of input voltage and output are constant, voltage VBIt is regarded as a constant, can from formula
To find out, the shape of input current waveform is to follow the voltage waveform change of node A.In the present embodiment, node A is taken from
The voltage of the MULT pin of PFC control chip.
It will be noted from fig. 1 that in common PFC controls, input power fluctuation is relatively big, causes output ripple big, need
Output capacitance that will be bigger.If by changing input current, allowing input power fluctuate in half power frequency period and diminish, then
Just in the case of ensureing same output ripple, reduce output capacitance.This patent utilizes waveform shaping circuit concept transfer A exactly
Voltage waveform, change the waveform of input current.In the present embodiment, while reducing output capacitance, the change of PF value
Change also little, explanation below.
In the present embodiment, input current IinhAnd VAFunction be:
VA(t)=| Iinh(t) | k, wherein f is work frequency, and T is power frequency period, ImhFor the amplitude of input current, k is
Proportionality coefficient.Actual Iinh(t) and VAT () waveform shape is respectively as shown in Fig. 3-1 and Fig. 3-2.Input current IinhT () in fact
Being an odd harmonic function, Fourier decomposition only has odd item.The function I of input currentinhT () can be expressed as:
Iinh(t)=Imh·H1·sin(ω·t)+Imh·H3·sin(3·ω·t)+Imh·H5·sin(5·ω·
t)+…(2)
Mathematically it is relatively difficult to solve H1、H3、H5... value, be relatively difficult to draw concrete PF value.In engineering
The harmonic value of certain function is generally obtained by software analysis.Show in the present embodiment by one group of actual parameter below
Effect.Take f=50Hz, T=20ms, t1=1ms, for aspect analysis, take Imh=1, have no effect on the analysis result of harmonic wave.Institute
The actual I obtainedinh(t) and VAT () waveform shape is exactly the waveform of Fig. 3-1 and Fig. 3-2.With software, the waveform of Fig. 3-1 is entered
Row Fourier analysis, as shown in Figure 4, first-harmonic, triple-frequency harmonics, quintuple harmonics, the component of the seventh harmonic divide the harmonic component obtained
Wei H1=0.396, H3=0.11, H5=0.048, H7=0.02, the harmonic wave of more high order is negligible, and can obtain:It can be seen that by the method for the present embodiment, PF value does not reduce too many.
The input power expression formula of common PFC is Pinn(t)=Vm·sin(2·π·f·t)·Imn*sin(2·π·
F t), in half period, integration can obtain
The inventive method input power expression formula is Pinh(t)=Vm·sin(2·π·f·t)·IinhT (), from formula
(2) know, IinhT () is odd harmonic function, in half period, odd harmonic is 0 with the integration of first-harmonic, soMake Imh=Imn/H1, then can be obtained by the input power as common PFC.
And current amplitude ImhIt is by the output voltage V of loop compensation circuitBControlling, loop compensation circuit can come according to output
Adjust VBThe size of voltage so that input power is mated with output.
The efficiency of transmission assuming voltage is 100%, then output voltage with the relation of input power isPoutFor the mean power in half period, VoIt is average output voltage,
CoutIt it is output capacitance.
By one group of actual parameter, the control method of this patent and the difference of common PFC are described intuitively, make Vm·Imn=
Vm·Imh·H1=40, Cout=1.2uF, Vo=380V, Pout=20W, substitutes into the formula of above-mentioned input power, it is possible to obtain
The waveform of Fig. 5.Fig. 5 is the variation diagram of half period interior input instantaneous power, it can be seen that, although the average merit in half period
Rate is the same, but little than common PFC of the instantaneous peak input power of the method for the present invention.And Fig. 6 is output voltage ripple
Shape, it can be seen that in the case of same output and output capacitance, the output ripple of the present invention wanting than common PFC
Little.In other words, under same output ripple, use the present invention just can use less output capacitance.The present embodiment
Method is simple, easily implements, can reequip with common pfc controller and obtain, and detection controls the PFC chip of class all on the market
Can be as the controller of the present invention.
Second embodiment
In an embodiment in 1, at wide scope input, the input voltage range of the most common 85V～265V, A point in Fig. 2
Voltage waveform shape can be varied from.Embodiment one is only used a Zener diode carry out input sample voltage cutting
Ripple, input voltage changes, and the relative position cut is different, and the waveform shape of obtained A point is also the most different.At input voltage
When being respectively 85V and 265V, in Fig. 2, the voltage waveform of A point is as shown in Figure 7.When input voltage is higher, the relative position of wave chopping
Lower, differ bigger with original sine wave, PF value can be lower, but output ripple can be less.
In order to make when inputting high-low pressure, duty changes inconspicuous.Propose the circuit of the second embodiment, such as Fig. 8
Shown in.Compared with Example 1, waveform shaping circuit 103 is different, adds one and compensates voltage, can compensate wave chopping
Position, when input voltage changes, the relative position of wave chopping can be basically unchanged.As shown in Figure 8, the waveform of PFC control circuit
Shaping circuit, including Zener diode D2, diode D2, diode D3, electric capacity C3, resistance R6, resistance R7；The sun of diode D3
Pole is for being connected with the bus after rectification, and the negative electrode of diode D3 passes through electric capacity C3 ground connection, after resistance R6 and resistance R7 series connection also
Being coupled to the two ends of electric capacity C3, the junction point between the anode of Zener diode Z2 with resistance R6 and resistance R7 is connected, voltage stabilizing two pole
The negative electrode of pipe Z2 is connected with the negative electrode of diode D2, and the anode of diode D2 is connected with the A point end of PFC control chip.The electricity of Fig. 8
In road, the effect of diode D3 and electric capacity C3 is sampling and the crest voltage keeping bus, after resistance R6 and R7 dividing potential drop, resistance R7
On voltage be exactly the compensation voltage of wave chopping.
When input voltage becomes big, the voltage on resistance R7 also can become big, then the voltage of A point wave chopping also can rise, this
Sample ensures that input voltage changes, and the relative position of institute's wave chopping is also basically unchanged.Fig. 9-1 is when input voltage divides in Fig. 8
Wei the waveform of A point voltage, the waveform of available Fig. 9-2 after normalized when exchanging 85V and 265V.Can from Fig. 9-2
Going out, in the case of input 85V and 265V, the relative position of both wave chopping is closely so that under different input voltages, circuit
Duty will not change significantly.
Below it is only the preferred embodiment of the present invention, it is noted that it is right that above-mentioned preferred implementation is not construed as
The restriction of the present invention, protection scope of the present invention should be as the criterion with claim limited range.For the art
For those of ordinary skill, without departing from the spirit and scope of the present invention, it is also possible to make some improvements and modifications, these change
Enter and retouch and also should be regarded as protection scope of the present invention.Such as control to use continuous mode control, Hysteresis control etc.；Voltage is changed
Circuit is in addition to BOOST circuit, it is also possible to use BUCK circuit, circuit of reversed excitation and cathode circuit etc..
Claims (10)
1. a pfc circuit, including PFC control chip, is wherein integrated with feedback control circuit, receives the defeated of input detecting circuit
Enter the output sampled voltage of sampled voltage and output detection circuit, and export control signal to carry out the work of voltage conversion circuit
Schema control；PFC control chip has reference voltage end, it is characterised in that: also include waveform shaping circuit, be used for blocking input
The crest of sampled signal, waveform shaping circuit is external between reference voltage end and the ground of PFC control chip.
Pfc circuit the most according to claim 1, it is characterised in that: described waveform shaping circuit, including voltage stabilizing two pole
Pipe, the negative electrode of Zener diode is connected with the reference voltage end of PFC control chip, the plus earth of Zener diode.
3. according to the pfc circuit shown in patent requirements 1, it is characterised in that: described waveform shaping circuit, including the second voltage stabilizing two pole
Pipe, the second diode, the 3rd diode, the 3rd electric capacity, the 6th resistance, the 7th resistance；3rd diode anode is used for and rectification
After bus be connected, the negative electrode of the 3rd diode pass through the 3rd capacity earth, be parallel to after the 6th resistance and the 7th resistant series
3rd electric capacity two ends, junction point and the anode of the second Zener diode between the 6th resistance and the 7th resistance are connected, and second is steady
The negative electrode of pressure diode cathode and the second diode is connected, the anode of the second diode and the reference voltage end of PFC control chip
It is connected.
4. according to the pfc circuit according to any one of claim 1-3, it is characterised in that: described feedback control circuit, including fortune
Calculate amplifier, loop compensation circuit, multiplier, comparator, clock circuit and d type flip flop, the input anode of operational amplifier with
Reference voltage is connected, and the input negative terminal of described operational amplifier is as the second input of feedback control circuit；Loop compensation electricity
Road is connected between the outfan of described operational amplifier and input negative terminal；The first input end of multiplier is as feedback control electricity
The first input end on road, the second input of multiplier is connected with the outfan of operational amplification circuit, the outfan of multiplier with
The input negative terminal of comparator is connected, the input anode of comparator as the 3rd input of feedback control circuit, comparator defeated
Going out the R input with d type flip flop to be connected, the outfan of clock circuit is connected with the S input of d type flip flop, the output of d type flip flop
Hold the outfan as feedback control circuit.
5. a PFC control circuit, is connected between rectification circuit and voltage conversion circuit, it is characterised in that: include input inspection
Slowdown monitoring circuit, output detection circuit and the pfc circuit described in Claims 1-4, input detecting circuit, the input after sampling rectification
Voltage generates input sample signal, it is provided that to PFC control circuit；Output detection circuit, the electricity of detection voltage conversion circuit output
Pressure, provides output sampled voltage for PFC control circuit.
PFC control circuit the most according to claim 5, it is characterised in that: described input detecting circuit, after being parallel to rectification
Bus and ground between, in order to detect the busbar voltage after rectification, provide reference voltage waveform for feedback control circuit.
7. according to the PFC control circuit according to any one of claim 5, it is characterised in that: described input detecting circuit, including
First resistance and the second resistance, the first resistance and the second resistant series connect, the junction point conduct of the first resistance and the second resistance
The outfan of input detecting circuit.
8. according to the PFC control circuit according to any one of claim 5, it is characterised in that: described output detection circuit, in parallel
Between the output voltage and ground of PFC control circuit, in order to detect the voltage of voltage conversion circuit output, for feedback control circuit
Output sampled voltage is provided.
9. according to the PFC control circuit according to any one of claim 5, it is characterised in that: described output detection circuit, including
3rd resistance and the 4th resistance, the 3rd resistance and the 4th resistant series connect, the 3rd resistance and the junction point conduct of the 4th resistance
The outfan of output detection circuit.
10. a Switching Power Supply, including rectification circuit and voltage conversion circuit, voltage conversion circuit is BOOST booster circuit, its
It is characterised by: between rectification circuit and voltage conversion circuit, be provided with the PFC according to any one of claim 5-9 control electricity
Road, described voltage conversion circuit, including inductance, N-MOS pipe, the first diode, the second electric capacity and the 5th resistance, one end of inductance
First input end as voltage conversion circuit；The other end of inductance drains and the anode phase of the first diode with N-MOS pipe
Even, the source electrode of N-MOS pipe passes through the 5th resistance eutral grounding, the source electrode of N-MOS pipe also as the second outfan of voltage conversion circuit,
The grid of N-MOS pipe is as the second input of voltage conversion circuit；The negative electrode of the first diode passes through the second capacity earth, the
The negative electrode of one diode is also as the first outfan of voltage conversion circuit.
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| CN201610808084.0A CN106208668B (en) | 2016-09-07 | 2016-09-07 | Pfc circuit, PFC control circuit and Switching Power Supply |
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| CN201610808084.0A CN106208668B (en) | 2016-09-07 | 2016-09-07 | Pfc circuit, PFC control circuit and Switching Power Supply |
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| CN108306526A (en) * | 2018-01-25 | 2018-07-20 | 北京航天发射技术研究所 | A kind of current hysteresis-band control circuit and control method |
| CN109585223A (en) * | 2018-12-05 | 2019-04-05 | 深圳南云微电子有限公司 | A kind of contactor control circuit |
| CN110504848A (en) * | 2019-07-24 | 2019-11-26 | 上海源微电子科技有限公司 | A kind of input current peak value modulator approach of Switching Power Supply |
| CN112653331A (en) * | 2020-12-24 | 2021-04-13 | 漳州科华技术有限责任公司 | Control method of DCDC converter and terminal equipment |
| CN112803753A (en) * | 2021-03-25 | 2021-05-14 | 毛昭祺 | Power factor correction converter |
| US11418110B2 (en) * | 2020-08-24 | 2022-08-16 | Acer Incorporated | Power converter and related power factor correction circuit capable of improving zero-crossing distortion |
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| US11418110B2 (en) * | 2020-08-24 | 2022-08-16 | Acer Incorporated | Power converter and related power factor correction circuit capable of improving zero-crossing distortion |
| CN112653331A (en) * | 2020-12-24 | 2021-04-13 | 漳州科华技术有限责任公司 | Control method of DCDC converter and terminal equipment |
| CN112803753A (en) * | 2021-03-25 | 2021-05-14 | 毛昭祺 | Power factor correction converter |
| CN112803753B (en) * | 2021-03-25 | 2022-02-11 | 杭州优特电源有限公司 | Power factor correction converter |
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| CN106208668B (en) | 2019-07-19 |
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