CN106208668B - 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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- CN106208668B CN106208668B CN201610808084.0A CN201610808084A CN106208668B CN 106208668 B CN106208668 B CN 106208668B CN 201610808084 A CN201610808084 A CN 201610808084A CN 106208668 B CN106208668 B CN 106208668B
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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)
- Rectifiers (AREA)
- Dc-Dc Converters (AREA)
Abstract
The present invention relates to field of switch power, and in particular to one kind can reduce pfc circuit, PFC control circuit and the Switching Power Supply using the PFC control circuit of output capacitance.With regard to a kind of pfc circuit provided by the present invention, chip is controlled including PFC, it is wherein integrated with feedback control circuit, receives the input sample voltage of input detecting circuit and the output sampled voltage of output detection circuit, and exports control signal to carry out the operating mode control of voltage conversion circuit；PFC, which controls chip, has reference voltage end, it is characterised in that: further includes waveform shaping circuit, for the wave crest of input sample signal to be truncated, waveform shaping circuit is external between the reference voltage end and ground of PFC control chip.Compared with prior art, the present invention circuit is simpler, cost is lower, it is easier to realize.
Description
Technical field
The present invention relates to field of switch power, and in particular to one kind can reduce the pfc circuit of output capacitance, PFC control electricity
The Switching Power Supply of road and the application PFC control circuit.
Background technique
With the development of electronic technology, also higher and higher to the requirement of Switching Power Supply, it is desirable that Switching Power Supply has the higher longevity
Life, smaller volume and lower cost.It is well known that the service life of current electrolysis capacitor only have thousands of hours to it is up to ten thousand when,
The high temperature lower service life can be shorter.Electrolytic capacitor is widely used in AC-DC Switching Power Supply, and electrolytic capacitor is to determine the Switching Power Supply longevity
Order most important device.Electrolytic capacitor has unit volume capacity big, advantage at low cost.Others capacitor such as thin-film electro at present
The problem of appearance, ceramic condenser etc. can not also substitute electrolytic capacitor completely, mainly be exactly because of volume and cost.So wanting substitution
Electrolytic capacitor must just have special control in circuit, reduce the requirement to output capacitance capacity.
The essence of pfc circuit is exactly to allow the waveform of input current to follow the wave of input voltage by certain control means
Deformation.There are two types of currently used PFC control methods.One is perseverance conducting controls, according to formulaWherein lead
Logical time Ton and PFC inductance sensibility reciprocal L is fixed, so that it may input current be allowed to be changed according to input voltage.Another kind is detection
Input voltage and PFC inductive current allow inductive current to follow the variation of input voltage, referred to as examine herein by feedback control
Observing and controlling system.On the market than more typically using the chip of detection control for L6562, the chip operation is in critical conduction mode.Pfc circuit
Input power is followed by input voltage variation, and input power is maximum at input voltage wave crest, the input power at zero passage
It is minimum.For inputting mean power 20W, when input voltage and input current are all in phase power frequency sine wave, half
In a power frequency period, for Instantaneous input power waveform as shown in Figure 1, at 1/4 power frequency period, the instantaneous power of input is maximum, has
40W.Since input power fluctuation is big, so just needing larger output storage capacitor, otherwise excessive output voltage ripple may
It will lead to certain device excessive pressure damages in circuit, so cannot 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, the fluctuation of limitation input current is sought in fact.
The waveform for changing input current can make PF value decline, and can be rolled over to both PF value and output capacitance by certain method
In.Such as the method in application number 201310304212.4, PFC control in the patent is substantially using checking control methods.
By signal synthetic method, the sinusoidal signal of 90 degree of phase difference is superimposed on the input sine voltage signal detected.
Allow PFC inductive current that this is followed to synthesize obtained signal.The amplitude of input current is limited at input voltage wave crest, is reduced
The peak value of instantaneous power, so as to reducing output capacitance.Since the patent is using signal synthetic method, in addition to needing
It wants common detection to control outside class PFC control chip, also to have phase-shift circuit and computing circuit, use multiple operation amplifiers
Device, circuit is complicated, at high cost.
Summary of the invention
The present invention solves the problems, such as that above-mentioned controling circuit structure is complicated, a kind of pfc circuit is provided, so that similarly exporting
Under ripple, smaller output capacitance can be used using the present invention, and control circuit is simple, cost is lower, is easy functionization.
With this corresponding, the present invention is further also provided based on the pfc circuit during solving above-mentioned technical problem
PFC control circuit and Switching Power Supply based on the PFC control circuit, so that controling circuit structure is simple, cost is lower, is easy
It is practical.
A kind of pfc circuit provided by the present invention, including PFC control chip are connect wherein being integrated with feedback control circuit
The input sample voltage of input detecting circuit and the output sampled voltage of output detection circuit are received, and exports control signal to carry out
The operating mode of voltage conversion circuit controls；PFC, which controls chip, has reference voltage end, it is characterised in that: further includes that waveform is whole
Shape circuit, for being truncated the wave crest of input sample signal, waveform shaping circuit be external in the reference voltage end of PFC control chip with
Between ground.
Preferably, the waveform shaping circuit, including a zener diode, the cathode and PFC of zener diode control
The reference voltage end of chip is connected, the plus earth of zener diode.
Preferably, the waveform shaping circuit, including the second zener diode, the second diode, third diode, third
Capacitor, the 6th resistance, the 7th resistance；Third diode anode with the bus after rectification for being connected, the cathode of third diode
By third capacity earth, third capacitor both ends, the 6th resistance and the 7th electricity are parallel to after the 6th resistance and the series connection of the 7th resistance
Tie point between resistance is connected with the anode of the second zener diode, the cathode of the second zener diode cathode and the second diode
It is connected, the anode of the second diode is connected with the reference voltage end of PFC control chip.
Preferably, the feedback control circuit, including operational amplifier, loop compensation circuit, multiplier, comparator, when
The input anode of clock circuit and d type flip flop, operational amplifier is connected with reference voltage, and the input negative terminal of the operational amplifier is made
For the second input terminal of feedback control circuit；Loop compensation circuit is connected to the output end and input negative terminal of the operational amplifier
Between；First input end of the first input end of multiplier as feedback control circuit, the second input terminal of multiplier and operation
The output end of amplifying circuit is connected, and the output end of multiplier is connected with the input negative terminal of comparator, and the input anode of comparator is made
For the third input terminal 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 terminal of d type flip flop, output end of the output end of d type flip flop as feedback control circuit.
The present invention also provides a kind of PFC control circuits, are connected between rectification circuit and voltage conversion circuit, including input
Detection circuit, output detection circuit and above-mentioned pfc circuit, input detecting circuit, the input voltage after sampling rectification generate defeated
Enter sampled signal, is supplied to PFC control circuit；Output detection circuit, the voltage of detection voltage conversion circuit output, is controlled for PFC
Circuit processed provides output sampled voltage.
Preferably, the input detecting circuit is parallel between the bus and ground after rectifying, to detect the mother after rectifying
Line voltage provides reference voltage waveform for feedback control circuit.
Preferably, the input detecting circuit, including first resistor and second resistance, first resistor are connected with second resistance
Output end of the tie point of connection, first resistor and second resistance as input detecting circuit.
Preferably, the output detection circuit, is parallel between the output voltage of PFC control circuit and ground, to detect
The voltage of voltage conversion circuit output, provides output sampled voltage for feedback control circuit.
Preferably, the output detection circuit, including 3rd resistor and the 4th resistance, 3rd resistor are connected with the 4th resistance
Output end of the tie point of connection, 3rd resistor and the 4th resistance as output detection circuit.
The present invention provides a kind of Switching Power Supply again, controls electricity including rectification circuit, voltage conversion circuit and above-mentioned PFC
Road, PFC control circuit are connected between rectification circuit and voltage conversion circuit, and voltage conversion circuit is BOOST booster circuit, packet
Include inductance, N-MOS pipe, first diode, the second capacitor and the 5th resistance, one end of inductance as voltage conversion circuit first
Input terminal；The other end of inductance is connected with the anode of the drain electrode of N-MOS pipe and first diode, and the source electrode of N-MOS pipe passes through the
Five resistance eutral groundings, the source electrode of N-MOS pipe are also used as the second output terminal of voltage conversion circuit, and the grid of N-MOS pipe is as voltage
Second input terminal of conversion circuit；The cathode of first diode passes through the second capacity earth, the also conduct of the cathode of first diode
First output end of voltage conversion circuit.
When applying the present invention in switching power circuit, a kind of new Switching Power Supply, including AC-DC power circuit are formed
And PFC control circuit, wherein AC-DC power circuit includes rectification circuit and voltage conversion circuit, and PFC control circuit includes defeated
Enter detection circuit, waveform shaping circuit, output detection circuit and feedback control circuit.The input terminal of the rectification circuit and friendship
Stream city is electrically connected, the first input end of the voltage conversion circuit, the input terminal of the input detecting circuit and the rectified current
The output end on road is connected, and the output end of the input detecting circuit and the first input end and waveform of the feedback control circuit are whole
The input terminal of shape circuit is connected, the input terminal phase of the first output end and the output detection circuit of the voltage conversion circuit
Even, the output end of the output detection circuit is connected with the second input terminal of the feedback control circuit, the voltage conversion electricity
The second output terminal on road is connected with the third input terminal of the feedback control circuit, the first output end of the feedback control circuit
It is connected with the second input terminal of the voltage conversion circuit.
The waveform shaping circuit includes a zener diode, the cathode of the zener diode and waveform shaping electricity
The input on road is connected, the plus earth of the zener diode.
The input detecting circuit includes first resistor and second resistance, and first resistor is parallel to after connecting with second resistance
Between the input terminal and ground of the input detecting circuit, the tie point of first resistor and second resistance is detected as the input
The output end of circuit.
The output detection circuit includes 3rd resistor and the 4th resistance, and 3rd resistor is parallel to after connecting with the 4th resistance
Between the input terminal and ground of the output detection circuit, the tie point of 3rd resistor and the 4th resistance detects electricity as the output
The output end on road.
The feedback control circuit includes operational amplifier, loop compensation circuit, multiplier, comparator, clock circuit and D
Trigger.The input anode of the operational amplifier is connected with reference voltage, and the input negative terminal of the operational amplifier is as institute
The second input terminal of feedback control circuit is stated, the loop compensation circuit is connected to output end and the input of the operational amplifier
Between negative terminal.The first input end of the multiplier is connected with the first input end of the feedback control circuit, the multiplier
The second input terminal be connected with the output end of the operational amplification circuit, the output end of the multiplier is defeated with the comparator
Enter negative terminal to be connected, the input anode of the comparator is connected with the third input terminal of the feedback control circuit, the comparator
Output be connected with the R input of the d type flip flop, the S input terminal phase of the output end of the clock circuit and the d type flip flop
Even, the output end of the d type flip flop is connected with the first output end of the feedback control circuit.
The voltage conversion circuit includes an inductance, a switching tube, a diode, a capacitor and the 5th electricity
Resistance.
Compared with prior art, the present invention circuit is simpler, cost is lower, it is easier to realize.
Detailed description of the invention
Fig. 1 is common PFC input power waveform diagram；
Fig. 2 is that the PFC control circuit of first embodiment of the invention is applied to the circuit original road figure of 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 waveform diagram 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 comparison diagram of the PFC control circuit of first embodiment of the invention and the input power of common PFC control；
Fig. 6 is the comparison of the PFC control circuit of first embodiment of the invention and the output voltage ripple of common PFC control
Figure；
Fig. 7 is the voltage oscillogram of A node in the PFC control circuit of first embodiment of the invention；
Fig. 8 is the circuit original road figure of the PFC control circuit of second embodiment of the invention；
Fig. 9-1 is the voltage oscillogram of A node in the PFC control circuit of second embodiment of the invention；
Fig. 9-2 is the waveform diagram in the PFC control circuit of second embodiment of the invention after the normalization of A node.
Specific embodiment
Chip is controlled using the PFC of detection control, error amplifier is generally included, 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 driving output
End.The function of input test side is the busbar voltage after detection rectification, and the function of exporting test side is detection PFC main power circuit
Output voltage, the cutoff frequency of the loop compensation circuit of usual PFC control is very low, and loop is very slow, output voltage test side
Voltage signal becomes the error signal of ripple very little after error amplifier, can be approximately DC voltage.The error signal with
Change with load, load is heavier, and error voltage is higher.The voltage signal of error signal and input test side is as multiplier
Input, obtain current reference signal after multiplication, the waveform of the signal and the waveform of input voltage are consistent, control input current with
With current reference signal, PFC is just achieved the effect that.
And control input current follow reference current signal be achieved in that main power topology by taking BOOST circuit as an example,
Drive output controls the conducting of BOOST circuit switch pipe, and the inductance of BOOST circuit is by excitation, and inductive current rises, current detecting
The current signal of end detection inductance, current signal is compared with current reference signal is by comparator, when current signal is than electric current base
BOOST circuit switch pipe is just turned off when calibration signal is high, clock circuit controls the switching frequency of BOOST circuit switch pipe, in this way
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
It is directly proportional to input current to be worth electric current, to achieve the effect that PFC is controlled.
In the present invention, waveform shaping circuit is increased, thus it is possible to vary PFC controls chip input voltage test side, thus
Achieve the effect that input current, the power distribution in half of power frequency period can be redistributed, reduces the peak value of input power,
So that output voltage ripple becomes smaller, and PF value influences very little.
It is described in detail below in conjunction with principle and embodiment of the attached drawing to invention.
First embodiment
The first embodiment of the present invention is as shown in Figure 2.A kind of Switching Power Supply, including AC-DC power circuit and PFC control electricity
Road, wherein AC-DC power circuit includes BD1 rectification circuit and voltage conversion circuit 101, and voltage conversion circuit 101 is also main function
Rate circuit, PFC control circuit are 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 output detection circuit 104 output sampled voltage, and export control signal come carry out voltage conversion electricity
The operating mode on road 101 controls.
The input terminal of rectification circuit BD1 is connected with electric main, the first input end of voltage conversion circuit 101, input inspection
The input terminal of slowdown monitoring circuit 102 is connected with the output end of rectification circuit BD1, the output end and feedback control of input detecting circuit 102
The first input end of circuit 105 is connected with the input terminal of waveform shaping circuit 103, the first output end of voltage conversion circuit 101
It is connected with the input terminal of output detection circuit 104, the output end of output detection circuit 104 and the second of feedback control circuit 105
Input terminal is connected, and the second output terminal of voltage conversion circuit 101 is connected with the third input terminal of feedback control circuit 105, feedback
First output end of control circuit 105 is connected with the second input terminal of voltage conversion circuit 101.
Wherein, integrated PFC control chip can be used in feedback control circuit 105, and PFC, which controls 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
The peripheral circuits such as slowdown monitoring circuit 104, PFC control chip and the composition pfc circuit of waveform shaping circuit 103, input detecting circuit 102,
Output detection circuit 104 and pfc circuit form PFC control circuit.
Waveform shaping circuit 103 includes zener diode Z1, and the cathode of zener diode Z1 is as waveform shaping circuit 103
Input terminal, with PFC control chip reference voltage end be connected；The plus earth of zener diode Z1.Reference voltage end is also
Exit from figure at marked A point, hereinafter referred to as A point end.
Input detecting circuit 102 includes resistance R1 and resistance R2, and resistance R1 is grounded after connecting with resistance R2, resistance R1 and electricity
Hinder output end of the tie point of R2 as input detecting circuit 102.And the tie point of resistance R1 and resistance R2 are chosen as node
A, detailed circuit analysis is unfolded.Node A can control chip from PFC and lead to external pin end, the bringing-out of node A
As 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, the same or similar functional pin, when the PFC for selecting different manufacturers controls chip, pin
The definition of title may be different, are not limited with pin name.
Output detection circuit 104 includes resistance R3 and resistance R4, and resistance R3 is grounded after connecting with resistance R4, resistance R3 and electricity
Hinder output end of the tie point of R4 as 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 terminal of feedback control circuit 105, loop compensation circuit is connected to output end and the input of operational amplifier U1
Between negative terminal.The output end of operational amplifier U1 is chosen as node B, detailed circuit analysis is unfolded.The of multiplier U4
First input end of one input terminal as feedback control circuit 105, the second input terminal and operational amplification circuit U1 of multiplier U4
Output end be connected, the output end of multiplier U4 is connected with the input negative terminal of comparator U2, the input anode conduct of comparator U2
The output of the third input terminal of feedback control circuit 105, comparator U2 is connected with the R input of d type flip flop U3, clock circuit
Output end is connected with the S input terminal of d type flip flop U3, first output of the output end of d type flip flop U3 as feedback control circuit 105
End.
Voltage conversion circuit 101 includes inductance L1, N-MOS pipe TR1, diode D1, capacitor C2 and resistance R5.Inductance L1's
First input end of the one end as voltage conversion circuit, the inductance L1 other end and the drain electrode of N-MOS pipe TR1 and the sun of diode D1
Extremely it is connected, the source electrode of N-MOS pipe TR1 is grounded by resistance R5, and the source electrode of N-MOS pipe TR1 is also used as voltage conversion circuit 101
Second output terminal, second input terminal of the grid of N-MOS pipe TR1 as voltage conversion circuit 101, the cathode and electricity of diode D1
Hold one end of C2, the cathode of diode D1 is also used as the first output end of voltage conversion circuit 101, another termination of capacitor C2
Ground.
The major function of each section is as follows in the present embodiment.Voltage conversion circuit 105 is BOOST booster circuit.Resistance R1
It is used to sample the input voltage after rectification with resistance R2, the effect of zener diode Z1 is that the wave crest of input sample signal is cut
It is disconnected.R3 and R4 be used for sampling and outputting voltage, loop compensation circuit is arranged relatively low cross-over frequency, be arranged in power frequency hereinafter,
For filtering out the working frequency ripple wave of output, then the output voltage of operational amplifier U1 can approximation regard DC voltage as.This is straight
Galvanic electricity press be shaped after input sample voltage after multiplier U4 is multiplied, obtain peak point current baseline threshold.R5 is used for
The electric current for detecting inductance L1, allows the current signal of inductance L1 to be compared with peak point current baseline threshold, when the peak value of inductance L1
When electric current is higher than peak point current baseline threshold, N-MOS pipe TR1 is allowed to turn off, so that the peak point current of inductance be allowed to follow peak point current
The variation of baseline threshold is finally reached the purpose of control input voltage and input current variation.The PFC of general detection control class controls core
Piece all controls the electric current of inductance L1 by this method.
After increasing 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 node A is derived below by waveform shaping electricity
After road 103 changes, brought effect.Assuming that the function of voltage of node A is VA=f (t).Usually in pfc circuit, loop is mended
The cross-over frequency repaid is all relatively low, for filtering out the fluctuation of power, so the voltage V of node BBCan be approximately considered is ripple very little
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 works in critical conduction mode, then input current Iin=1/2*Ipeak.It can be obtained in conjunction with above-mentioned formula, Iin=
VA*VB/(2*R5), in the case where input voltage and constant output power, voltage VBIt is regarded as a constant, it can from formula
To find out, the shape of input current waveform is that the voltage waveform of node A is followed to change.In the present embodiment, node A is taken from
PFC controls the voltage of the MULT pin of chip.
It will be noted from fig. 1 that input power fluctuation is larger, causes output ripple big in common PFC control, need
Want biggish output capacitance.If it allows input power to fluctuate in half of power frequency period by changing input current and becomes smaller, then
Just in the case where guaranteeing same output ripple, reduce output capacitance.This patent is exactly to utilize waveform shaping circuit concept transfer A
Voltage waveform, to change the waveform of input current.In the present embodiment, while reducing output capacitance, the change of PF value
Change is also little, illustrates below.
In the present embodiment, input current IinhAnd VAFunction are as follows:
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 VA(t) waveform shape is respectively as shown in Fig. 3-1 and Fig. 3-2.Input current Iinh(t) in fact
It is an odd harmonic function, Fourier decomposition only has odd item.The function I of input currentinh(t) it can indicate are as follows:
Iinh(t)=Imh·H1·sin(ω·t)+Imh·H3·sin(3·ω·t)+Imh·H5·sin(5·ω·
t)+…(2)
Mathematically compare and is difficult to solve H1、H3、H5... value, compare and be difficult to obtain specific PF value.In engineering
The harmonic value of some function is usually obtained by software analysis.It is shown in the present embodiment with one group of actual parameter below
Effect.F=50Hz, T=20ms, t1=1ms are taken, for aspect analysis, takes Imh=1, have no effect on the analysis result of harmonic wave.Institute
Obtained actual Iinh(t) and VA(t) waveform shape is exactly the waveform of Fig. 3-1 and Fig. 3-2.With software to the waveform of Fig. 3-1 into
Row Fourier analysis, obtained harmonic component as shown in figure 4, fundamental wave, triple-frequency harmonics, quintuple harmonics, the seventh harmonic component point
It Wei not H1=0.396, H3=0.11, H5=0.048, H7=0.02, the harmonic wave of more high order can be ignored, and can find out:As can be seen that PF value is too many there is no reducing with the method for the present embodiment.
The input power expression formula of common PFC is Pinn(t)=Vm·sin(2·π·f·t)·Imn*sin(2·π·
Ft), integrating in half period can obtain
The method of the present invention input power expression formula is Pinh(t)=Vm·sin(2·π·f·t)·Iinh(t), from formula
(2) know, IinhIt (t) is odd harmonic function, the integral of odd harmonic and fundamental wave is 0 in half period, soEnable Imh=Imn/H1, then can be obtained by the input power as common PFC.
And current amplitude ImhIt is the output voltage V by loop compensation circuitBCome what is controlled, loop compensation circuit can according to output power come
Adjust VBThe size of voltage, so that input power is matched with output power.
Assuming that the efficiency of transmission of voltage is 100%, then the relationship of output voltage and input power isPoutFor the mean power in half period, VoIt is average output voltage,
CoutIt is output capacitance.
Intuitively illustrate the control method of this patent and the difference of common PFC with one group of actual parameter, enables Vm·Imn=
Vm·Imh·H1=40, Cout=1.2uF, Vo=380V, Pout=20W substitutes into the formula of above-mentioned input power, so that it may obtain
The waveform of Fig. 5.Fig. 5 is the variation diagram of input instantaneous power in half period, it can be seen that although the average function in half period
Rate is that the instantaneous peak input power of the same but of the invention method is smaller than common PFC.And Fig. 6 is output voltage wave
Shape, it can be seen that in same output power and output capacitance, output ripple of the invention than common PFC than
It is small.In other words, under same output ripple, smaller output capacitance can be used using the present invention.The present embodiment
Method is simple, is easy to implement, can reequip to obtain with common pfc controller, detection controls the PFC chip of class all on the market
It can be used as controller of the invention.
Second embodiment
It in embodiment in 1, is inputted in wide scope, such as the input voltage range of common 85V~265V, A point in Fig. 2
Voltage waveform shape can be varied.Only input sample voltage is cut with a zener diode in embodiment one
Wave, input voltage change, and the relative position cut is different, and the waveform shape of acquired A point is also just different.In input voltage
When respectively 85V and 265V, the voltage waveform of A point is as shown in Figure 7 in Fig. 2.When input voltage is higher, the relative position of wave chopping
It is lower, differ bigger with original sine wave, PF value can be lower, but output ripple can be smaller.
In order to make when inputting high-low pressure, working condition changes unobvious.Propose the circuit of second embodiment, such as Fig. 8
It is shown.Compared with Example 1, waveform shaping circuit 103 is different, increases an offset voltage, can compensate wave chopping
Position, when input voltage variation, 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, capacitor C3, resistance R6, resistance R7；The sun of diode D3
For being connected with the bus after rectification, the cathode of diode D3 is grounded by capacitor C3 for pole, resistance R6 and resistance R7 connect after simultaneously
The both ends of capacitor C3 are coupled to, the anode of zener diode Z2 is connected with the tie point between resistance R6 and resistance R7, two pole of pressure stabilizing
The cathode of pipe Z2 is connected with the cathode 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
The effect of diode D3 and capacitor C3 are sampling and the crest voltage for keeping bus in road, after resistance R6 and R7 are divided, resistance R7
On voltage be exactly wave chopping offset voltage.
When input voltage becomes larger, the voltage on resistance R7 can also become larger, then the voltage of A point wave chopping can also 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 in Fig. 8 when input voltage point
The waveform of Fig. 9-2 can be obtained after normalized for the waveform of A point voltage when Wei not exchange 85V and 265V.It can from Fig. 9-2
Out, when inputting 85V and 265V, the relative position of the two wave chopping is very close, so that under different input voltages, circuit
Working condition will not change significantly.
The above is only the preferred embodiment of the present invention, it is noted that above-mentioned preferred embodiment is not construed as pair
Limitation of the invention, protection scope of the present invention should be defined by the scope defined by the claims..For the art
For those of ordinary skill, without departing from the spirit and scope of the present invention, several improvements and modifications can also be made, these change
It also should be regarded as protection scope of the present invention into retouching.For example control is using continuous mode control, Hysteresis control etc.；Voltage conversion
Circuit, can also be using BUCK circuit, circuit of reversed excitation and cathode circuit etc. other than BOOST circuit.
Claims (8)
1. a kind of pfc circuit, including PFC control chip receive the defeated of input detecting circuit wherein being integrated with feedback control circuit
Enter the output sampled voltage of sampled voltage and output detection circuit, and exports control signal to carry out the work of voltage conversion circuit
Scheme control；PFC, which controls chip, has reference voltage end, it is characterised in that: further includes waveform shaping circuit, for input to be truncated
The wave crest of sampled signal, waveform shaping circuit are external between the reference voltage end and ground of PFC control chip；
The waveform shaping circuit, including the second zener diode, the second diode, third diode, third capacitor, the 6th electricity
Resistance, the 7th resistance；For third diode anode for being connected with the bus after rectification, the cathode of third diode passes through third capacitor
Third capacitor both ends, the connection between the 6th resistance and the 7th resistance are parallel to after ground connection, the 6th resistance and the series connection of the 7th resistance
Point is connected with the anode of the second zener diode, and the second zener diode cathode is connected with the cathode of the second diode, and the two or two
The anode of pole pipe is connected with the reference voltage end of PFC control chip.
2. pfc circuit according to claim 1, it is characterised in that: the feedback control circuit, including operational amplifier,
Loop compensation circuit, multiplier, comparator, clock circuit and d type flip flop, input anode and the reference voltage phase of operational amplifier
Even, second input terminal of the input negative terminal of the operational amplifier as feedback control circuit；Loop compensation circuit is connected to institute
It states between the output end of operational amplifier and input negative terminal；The first input end of multiplier is first defeated as feedback control circuit
Enter end, the second input terminal of multiplier is connected with the output end of operational amplification circuit, the output end of multiplier and comparator it is defeated
Enter negative terminal to be connected, third input terminal of the input anode of comparator as feedback control circuit, the output of comparator and d type flip flop
R input be connected, the output end of clock circuit is connected with the S input terminal of d type flip flop, and the output end of d type flip flop is as feeding back
The output end of control circuit.
3. a kind of PFC control circuit, is connected between rectification circuit and voltage conversion circuit, it is characterised in that: examined including input
Slowdown monitoring circuit, output detection circuit and pfc circuit of any of claims 1 or 2, input detecting circuit, the input after sampling rectification
Voltage generates input sample signal, is supplied to PFC control circuit；Output detection circuit, the electricity of detection voltage conversion circuit output
Pressure, provides output sampled voltage for PFC control circuit.
4. PFC control circuit according to claim 3, it is characterised in that: the input detecting circuit, after being parallel to rectification
Bus and ground between, to detect rectification after busbar voltage, provide reference voltage waveform for feedback control circuit.
5. PFC control circuit according to claim 3, it is characterised in that: the input detecting circuit, including first resistor
And second resistance, first resistor and second resistance are connected in series, the tie point of first resistor and second resistance is as input detection
The output end of circuit.
6. PFC control circuit according to claim 3, it is characterised in that: the output detection circuit is parallel to PFC control
Between the output voltage and ground of circuit processed, to detect the voltage of voltage conversion circuit output, provided for feedback control circuit defeated
Sampled voltage out.
7. PFC control circuit according to claim 3, it is characterised in that: the output detection circuit, including 3rd resistor
With the 4th resistance, 3rd resistor and the 4th resistance are connected in series, and the tie point of 3rd resistor and the 4th resistance is as output detection
The output end of circuit.
8. a kind of Switching Power Supply, including rectification circuit and voltage conversion circuit, voltage conversion circuit is BOOST booster circuit,
It is characterized in that: being equipped with PFC control electricity described in any one of claim 3-7 between rectification circuit and voltage conversion circuit
Road, the voltage conversion circuit, including inductance, N-MOS pipe, first diode, the second capacitor and the 5th resistance, one end of inductance
First input end as voltage conversion circuit；The other end of inductance and the drain electrode of N-MOS pipe and the anode phase of first diode
Even, the source electrode of N-MOS pipe is also used as the second output terminal of voltage conversion circuit by the 5th resistance eutral grounding, the source electrode of N-MOS pipe,
Second input terminal of the grid of N-MOS pipe as voltage conversion circuit；The cathode of first diode passes through the second capacity earth, the
The cathode of one diode is also used as the first output end 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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| CN106208668B true CN106208668B (en) | 2019-07-19 |
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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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 |
| CN109585223B (en) * | 2018-12-05 | 2020-02-14 | 深圳南云微电子有限公司 | Contactor control circuit |
| CN110504848B (en) * | 2019-07-24 | 2021-07-16 | 上海源微电子科技有限公司 | Input current peak value modulation method of switching power supply |
| TWI746125B (en) * | 2020-08-24 | 2021-11-11 | 宏碁股份有限公司 | Power converter and related power factor correction circuit capable of improving zero-crossing distortion |
| CN112653331B (en) * | 2020-12-24 | 2022-05-10 | 漳州科华技术有限责任公司 | Control method of DCDC converter and terminal equipment |
| 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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| CN103023299A (en) * | 2011-09-26 | 2013-04-03 | 南京博兰得电子科技有限公司 | Control method of power factor conversion device |
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| CN103280965A (en) * | 2011-09-14 | 2013-09-04 | 矽力杰半导体技术(杭州)有限公司 | Power factor correction control circuit capable of reducing EMI |
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