CN103560662B - A kind of PFC control method and control device - Google Patents
A kind of PFC control method and control device Download PDFInfo
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- CN103560662B CN103560662B CN201310530668.2A CN201310530668A CN103560662B CN 103560662 B CN103560662 B CN 103560662B CN 201310530668 A CN201310530668 A CN 201310530668A CN 103560662 B CN103560662 B CN 103560662B
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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
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- 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
Abstract
The invention discloses a kind of PFC control method and device, mains voltage and the sinusoidal wave first-harmonic of a distortionless standard in-phase are compared, finally obtain the distorted signal with appropriate first-harmonic, distorted signal reflects the distortion situation of civil power, this signal is utilized to remove the operating current of control PFC device, make the operating current of PFC device in half waveform of civil power, when there is heavy duty instantaneously, the operating current that the consumption of this device is very little or do not consume, and in relative underloading moment, consume larger operating current, reduce line voltage wave distortion, the overall PF value realizing power unit like this raises, other distortion load is there is in power unit, PFC device still can works fine, the overall PF value of power unit is promoted.
Description
Technical field
The present invention relates to a kind of PFC control method for power factor correction (PFC) device, the invention still further relates to the control device using said method.
Background technology
Industrial and civilianly all often need various grid ac voltage to become direct current, or even the direct current of isolation, along with national standard is to the further requirement of the power factor (PF) of electrical appliance, at present, to Switching Power Supply all power factor requirements of more than consumed power 75W, namely require that the operating current waveform fundamental sum voltage waveform of circuit is identical.
Existing circuit of power factor correction addresses this problem at present, and circuit of power factor correction, referred to as pfc circuit, is the abbreviation of PowerFactorCorrection.
Note: 75W, data from CNS GB17625.1-1998, is called " Harmonic Current Limits (the every phase input current≤16A of equipment) that low-voltage electrical and electronic equipment send ".
Traditional BOOST power factor corrector solves this problem well, and its operation principle can see " principle of Switching Power Supply and the design " the 190th page, 191 pages of Electronic Industry Press, this book ISBN 7-121-00211-6.
Speak by the book, power factor refers to the ratio of input active power and input apparent power; Traditional power factor corrector is also divided into passive and active two kinds, Active Power Factor Correction (APFC:ActivePowerFactorCorrection) is used widely at present, and the conventional topology of current APFC circuit has: boost type (Boost); Buck (Buck); Lifting/lowering pressure type (Buck/Boost); Inverse-excitation type (Flyback), and directly referred to as pfc circuit.And control method is also a lot, discontinuous current mode control methods, critical current mode continuous control method, current peak control methods, current hysteresis-band control method, Average Current Control Method, one circle control method, their common feature is exactly that the operating current waveform fundamental sum voltage waveform of requirement pfc circuit is identical.
This current waveform of existing PFC and the synchronous method of voltage waveform, when input AC electricity is standard sinusoidal wave, effect is fine, Fig. 1 voltage curve (curve that in Fig. 1, upper figure y-axis U is corresponding) shows the waveform under nominal 220VAC of China's civil power, its peak value is 311V, in Fig. 1, current curve (curve that in Fig. 1, upper figure y-axis I is corresponding) shows the operating current waveform of existing pfc circuit, electric current and voltage homophase, comparatively ideal pfc circuit is exactly use electrical property in order to what obtain this pure resistance characteristic.
In fact, the voltage waveform of commercial power and civil power, due to a variety of causes, is not the sine wave of standard, the voltage waveform shown in Fig. 2, be exactly Cang Lian industry park, Luogang District, Guangzhou morning on June 24th, 2013 8:32 divide the commercial power waveform of collection, now most factory goes to work; Because oscillographic maximum input voltage peak-to-peak value is only about 300V, conveniently see waveform, employ rectification circuit to after AC rectification, without any filter capacitor, bring the power resistor of 4.7K/20W as load, oscilloscope is connected on power resistor two ends and gathers and obtain, and oscilloscope is Agilent DSO-X3024A digital oscilloscope.
As everyone knows, the distortion that naked eyes can be observed, the distortion factor is all greater than 10%, for the voltage waveform shown in Fig. 2, the current waveform that existing PFC obtains under the alternating voltage of this distortion as shown in Figure 3, the pfc circuit of this pure resistance characteristic, its current phase and voltage-phase homophase.Existing pfc circuit is for the alternating voltage waveform not direct improvement result of distortion.
Fig. 4 shows the deficiency of existing pfc circuit in electric power system, and what AC power AC exported is the sine wave of standard, as 1 indication in Fig. 4; Power because of superconductor and still cannot popularize at present, therefore the equivalent internal resistance that resistance Ro1 and Ro2 is supply line is set, and load RL1 is the equivalent of all electric loadings except power unit 5, generally, load RL1 is nonlinear load, its terminal voltage is the waveform of distortion, as 2 indications in Fig. 4; Resistance Ro3 and Ro4 is the equivalent internal resistance of the supply line of power unit 5, and load RL2 is the load of power unit 5.
When power unit 5 is a good power factor demonstration unit, namely load RL2 is the pfc circuit of purely resistive, between the feeder ear 3,4 of so power unit 5, equally there is the supply waveform of distortion, be not difficult to analyze from Fig. 4, this waveform is that amplitude is lower, as 2 indications in Fig. 4.
Due to the constraint of relevant criterion, if the power supply adaptor, charger for mobile phone, thyristor speed control fan etc. of notebook computer is all without Active PFC.Here, the load of this non-purely resistive is referred to as distortion load, although power is little, but One's name is legion, cause the current sinking of load RL1 in Fig. 4 to distort, also there is distortion in the terminal voltage of load RL1, correspondingly, when using the pfc circuit of prior art in power unit 5, the electric current that flows through resistance Ro3 and Ro4 is still distortion.
When being also connected to distortion load between the feeder ear 3,4 of power unit 5, the current distortion flowing through resistance Ro3 or Ro4 worsens further.The electric current flowing through resistance Ro3 or Ro4 is the operating current of the power unit of power unit 5.
To sum up, the deficiency of existing pfc circuit in electric power system mainly contains 2 points:
(1) the operating current waveform of the power unit at existing pfc circuit place cannot be improved;
(2) there is other distortion load in power unit, the operating current waveform of power unit worsens further.
Namely existing pfc circuit does not have improvement result to the electric current of the distortion of periphery in electric power system.
Summary of the invention
Have in view of that, the object of the invention is the deficiency being to solve the existence of existing pfc circuit, the electric current of a kind of PFC control method to distortion in power unit is provided to be improved effect, when there is other distortion load in power unit, the present invention can improve the operating current of power unit, and the overall PF value of power unit is improved.
Another object of the present invention is also to provide a kind of control device using said method.
The object of the present invention is achieved like this, a kind of PFC control method for PFC device, detect the input AC piezoelectric voltage waveform of PFC device input, and the alternating current voltage waveform of described input is decayed to without distortion the voltage waveform of the first effective value, the voltage waveform of the first described effective value and the first standard first-harmonic are carried out subtraction, obtain the first waveform, the effective value of described first standard first-harmonic equals the first described effective value and frequently homophase same with the voltage waveform of the first described effective value; The effective value of the first described waveform and the ratio of the first described effective value are the distortion factor; Adopt adder that the first described waveform and the second standard first-harmonic are added again and obtain the second waveform; The second described standard first-harmonic and the alternating current of described input are with frequency homophase, and when the described distortion factor is greater than the first limit value, the effective value of the second described standard first-harmonic is zero; When the described distortion factor is below the first described limit value, the effective value of the second described standard first-harmonic is inversely proportional to the described distortion factor; Adopt Current feedback switch converters in described PFC device, make described PFC device input current waveform follow the second described waveform absolute value.
The present invention also provides a kind of PFC control device, comprising:
One attenuation units, for decaying to the first effective value without distortion by the alternating current voltage waveform of described input;
One first standard first-harmonic generation unit, for generate an effective value equal the first described effective value and with the alternating current of input the first standard first-harmonic with frequently homophase;
One subtraction amplifying unit, for the voltage waveform of the first described effective value and the first standard first-harmonic are carried out subtraction, obtains the first waveform;
One second standard first-harmonic generation unit, for generating and the second standard first-harmonic of the alternating current inputted with frequency homophase, and when the described distortion factor is greater than the first limit value, the effective value of the second described standard first-harmonic is zero; When the described distortion factor is below the first described limit value, the effective value of the second described standard first-harmonic is inversely proportional to the described distortion factor; The effective value of described first waveform and the ratio of described first effective value are the distortion factor;
One sum unit, obtains the second waveform for the first described waveform and the second standard first-harmonic being added;
The absolute value of described second waveform follows value as the current feedback of control PFC device input current waveform; Namely PFC device input current waveform is made to follow the second described waveform absolute value.
By the technical scheme described above, detect the voltage waveform of the alternating current of input, and the alternating current voltage waveform of input is decayed to the first effective value without distortion, this is because under PFC device is generally operational in civil power, input voltage is very high, decay into low pressure, to guarantee that follow-up circuit is not damaged, use common divider resistance can realize this function; The voltage waveform of the first effective value and an effective value equal the first effective value, carry out subtraction with the first standard first-harmonic of frequency homophase, obtain the first waveform, the voltage waveform of the first effective value, for the mains waveform of distortion, deduct the first standard first-harmonic that effective value is equal, the first waveform obtained is distorted waveform.If the mains waveform of distortion as mentioned before, be " being cut top " close to during summit, so, after deducting the equal standard first-harmonic of effective value, " the first waveform " that obtain is the corresponding distorted waveform lower at " when cutting top " output voltage.When the distortion factor is greater than the first limit value, the effective value of the second standard first-harmonic is zero, and namely the second waveform and the first waveform are equal, switch converters in PFC device, adopt current feedback technology, make the input current waveform of PFC device follow the second waveform, namely follow the first waveform.
Namely when mains waveform is when close to when " to be cut top " during summit corresponding, at this moment current sinking is less for the input current waveform of PFC device, is even zero.Mains waveform is when close to when " to be cut top " during summit corresponding, exactly because the peak rectifier circuit of other electrical equipment various causes, current sinking is very big, mains waveform distortion is caused by the internal resistance of supply lines, and PFC control method of the present invention, be exactly pass through the mains waveform of distortion, with a Standard basis Bob comparatively, standard first-harmonic is a clean pure sine wave, himself distortion factor is extremely low, relatively, the voltage range lower than standard first-harmonic, illustrate at this interval, the electric current that civil power is consumed by other electrical equipment is excessive, and it is interval at this, the PFC device that PFC control method of the present invention controls, current sinking is less, correspondingly, compared with standard first-harmonic, the interval that minimum voltage is corresponding, because the current feedback technology of PFC device circuit itself, the input electric current of PFC device can be down to zero.
Namely achieve, when other electrical appliance in power unit, the electric current of consumption is large, and PFC device is by passive distortion detection, in the interval that other electrical equipment power consumption is large, the present invention can make PFC device reduce operating current, even reduce to zero, make the PF value of power unit entirety raise like this.
When input mains waveform distortion very little time, mains waveform and Standard basis Bob comparatively after, the voltage of the first waveform is close to zero, if do not take special measure, the current feedback technology of subsequent conditioning circuit directly cannot be followed the tracks of the first waveform and be carried out work.By adder, the first waveform and the addition of the second standard first-harmonic are obtained the second waveform, when the distortion factor is below the first limit value, the effective value of the second standard first-harmonic is inversely proportional to the distortion factor, and namely the voltage of the first waveform is close to zero, and namely the distortion factor is more close to zero, the effective value of the second standard first-harmonic is higher, like this, in the second waveform obtained, the composition of first-harmonic is more, the switch converters in PFC device, adopt current feedback technology, make the input current waveform of PFC device follow the second waveform.At this moment, along with the reduction of the distortion factor, this control method is more and more close to traditional PFC control effects.
By above-mentioned operation principle, can find out that beneficial effect of the present invention is:
(1) improve the operating current waveform of the power unit at place, the PF value of power unit entirety is raised;
(2) there is other distortion load in power unit, PFC device still can works fine;
(3) because the overall PF value of power unit is promoted, the inverse electrical equipment of wind-force, photovoltaic generation becomes easy to mains-supplied.
Accompanying drawing explanation
Fig. 1 is operating voltage, the current waveform figure of existing pfc circuit;
Fig. 2 is the oscillogram of civil power pure resistance load through commutating zone in actual measurement somewhere, Guangzhou;
Fig. 3 is the current waveform figure that existing PFC obtains under the alternating voltage of distortion;
Fig. 4 illustrates the equivalent circuit diagram of existing pfc circuit in electric power system;
Fig. 5 is first embodiment of the invention theory diagram;
Fig. 6 is second embodiment of the invention theory diagram.
Embodiment
First embodiment
Fig. 5 shows the theory diagram of the first embodiment, show the employing Current feedback PFC device of application the inventive method, comprise: the rectifier bridge be made up of four rectifier diodes Da, Db, Dc, Dd, and the classical BoostPFC circuit topology that inductance L 1 and power tube Q1, diode D1, electric capacity C1 form; And feedback signal attenuation units 1/H, comparator unit, Current peak value detect circuit I A composition current feedback part; Comparator unit also comprises built-in current error amplifier, pulse width modulator and driver etc., and belong to prior art, do not draw in Fig. 5, its load is the main power MOS pipe Q1 of a classical pfc circuit topology; Attenuation units 1/H inside also comprises built-in reference voltage and error amplifier, and also belong to prior art, do not draw in Fig. 5, the function of attenuation units is dividing potential drop, also makes voltage divider.Its PFC control device adopts control method of the present invention to control, by attenuator 1/K, wave recovery unit, BEF filter unit, clipping unit, BPF filter unit, voltage-controlled amplifier A1, summing circuit A2, accurate full-wave rectifying circuit A3, multiplier M.
The output valve Y of accurate full-wave rectifying circuit A3 is exactly the signal that control method of the present invention obtains, method comprises: in the PFC device of Fig. 5, the alternating current voltage UAC detecting input exports half waveform W1 through rectification, and by attenuator 1/K, wave recovery unit the alternating current U of input
aCdecay to the first effective value without distortion, in Figure 5, be inverted into normal sine wave through wave recovery unit Cycle by Cycle, the effective value that namely in Fig. 5, waveform WR1 is corresponding, is also denoted as WR1, voltage waveform and an effective value of the first effective value WR1 equal the first effective value, the first standard first-harmonic with frequency homophase carries out subtraction, obtain the first waveform WF1, in Figure 5, by this function of BEF filter unit circuit realiration, BEF filter unit circuit is band stop filter, the filtering first-harmonic of waveform WR1, the first standard first-harmonic with frequency homophase is the virtual ripple of band stop filter BEF filter unit, automatically the first effective value WR1 is equaled, be the first-harmonic of industrial-frequency alternating current, the output of BEF filter unit is the distorted waveform of industrial-frequency alternating current, be the first described waveform, as the waveform of the some correspondence of WF1 indication in Fig. 5,
Obviously, standard first-harmonic mentioned in this article refers to that the distortion factor is the sine wave of zero, and with the alternating current same frequency same-phase of input, be called for short with frequently homophase, namely with the voltage waveform of the first effective value also with homophase frequently;
Obviously, the effective value of the first waveform WF1 and the ratio of the first effective value WR1 are distortion factor THD, adopt adder A2 that the first waveform WF1 and the second standard first-harmonic WS2 is added and obtain the second waveform WF2, the alternating current of the second standard first-harmonic WS2 and input is with frequency homophase, in Figure 5, by this function of BPF filter unit circuit realiration, BPF filter unit circuit is band pass filter, first effective value WR1 after amplitude limiter circuit, more just can obtain the second standard first-harmonic WS2 of alternating current that is pure and input with frequency homophase through BPF filter unit;
When distortion factor THD is greater than the first limit value, the effective value of the second standard first-harmonic WS2 is zero, when the distortion factor is below the first limit value, the effective value of the second standard first-harmonic is inversely proportional to distortion factor THD, switch converters in PFC device, adopt current feedback technology, make the input current iL waveform of PFC device follow the absolute value of the second waveform WF2;
Utilize voltage-controlled amplifier A1 to realize above-mentioned functions in Fig. 5, when the effective value hour of the first waveform WF1 that BEF filter unit exports, namely when the distortion factor is below the first limit value, the gain of voltage-controlled amplifier A1 is high; When the effective value of the first waveform WF1 that BEF filter unit exports is large, when the distortion factor is greater than the first limit value, the gain of voltage-controlled amplifier A1 is extremely low, is even zero;
Fig. 5 obtains absolute value by accurate full-wave rectifying circuit A3 to the second waveform WF2 precision rectifying;
The output voltage Vo of PFC device, the i.e. terminal voltage of filter capacitor C1, through attenuation units 1/H internal circuit dividing potential drop, and and attenuation units 1/H inside reference voltage V r relatively after, input to the error amplifier VA process of attenuation units 1/H inside, obtain output voltage signal X;
The output absolute value Y of accurate full-wave rectifying circuit A3 and above-mentioned output voltage signal X is added to the input of multiplier M jointly, the output Z=XY of multiplier M, the output Z of multiplier M is as the reference signal of Current Feedback Control, give comparator unit, after the switching current iS detected value exported with Current peak value detect circuit I A compares, the current error amplifier CA built-in through comparator is added to built-in PWM and driver, to control the break-make of main power MOS pipe Q1, thus make the output valve Y waveform of the waveform of input current (i.e. the electric current of inductance L 1) iL and accurate full-wave rectifying circuit A3 basically identical.
Achieve when the mains waveform distortion inputted is very little like this, mains waveform and Standard basis Bob comparatively after, the voltage of the first waveform WF1 obtained is close to zero, if do not take special measure, the current feedback technology of subsequent conditioning circuit directly cannot be followed the tracks of the first waveform WF1 and be carried out work.First limit value sets to address this problem, with summing circuit A2, the first waveform WF1 and the second standard first-harmonic WS2 addition is obtained the second waveform WF2, when the distortion factor is below the first limit value, the effective value of the second standard first-harmonic WS2 is inversely proportional to the distortion factor, namely the voltage of the first waveform is close to zero, namely the distortion factor is more close to zero, the effective value of the second standard first-harmonic is higher, like this, in the second waveform WF2 obtained, the composition of first-harmonic is more, switch converters in PFC device of the present invention, adopt current feedback technology, the input current iL waveform of PFC device is made to follow the absolute value Y of the second waveform.At this moment, along with the reduction of the distortion factor, control method of the present invention is more and more close to traditional PFC control effects.According to power and the conceivable calibration result of PFC device, i.e. other distortion bearing power of the maximum permission of PFC device of the present invention, determines the size of the first limit value.
As the operation principle in technical scheme, present invention achieves and the distortion voltage waveform in power unit circuit is detected, in the half-wave of alternating current voltage, the voltage relatively high moment, namely in supply line with the electric loading relatively light moment, realize the work of PFC device or current sinking larger; In the half-wave of alternating current voltage, the voltage relatively low moment, namely relatively weigh the moment by electric loading in supply line, realizing PFC device current sinking is zero or less, achieves like this and corrects the overall PF value of power unit, the current harmonics of power unit entirety is greatly reduced, improve the input power factor of power unit, and, when the power factor of power unit itself is very high, control method of the present invention still can realize PFC device and work well, thus realizes goal of the invention.
When inductive current peak is by the change of distortion factor rule, when changing to alternating current half-wave with interim maximum from zero, can occur at a time with distorted waveform, the change of the duty ratio D of main power MOS pipe Q1 is also with the output valve Y of accurate full-wave rectifying circuit A3 and certain determining positions of place half-wave, namely in half power frequency period, duty ratio is greater than 0.5 sometimes, is sometimes less than 0.5; Therefore subharmonic oscillation (Sub-harmonicoscillation) is likely produced.In order to prevent the appearance of subharmonic oscillation, increase a slope-compensation function (Slopecompensation) at the input of comparator or claim slope (Ramp) penalty function, as shown in SC1 in Fig. 5, so that in the extensive excursion of duty ratio, circuit energy steady operation.Adopt other to work as current hysteresis-band control mode, this part of SC1 can be saved.
From the principle, any one DC-DC converter topology, as Buck, Boost, Flyback, SEPIC, and even Cuk converter can be used as the main circuit of PFC.But, due to the special benefits of Boost, be applied more broadly in PFC.Embodiment one, only for the PFC device that Boost current peak PFC adopts control method of the present invention to realize, illustrates the basic functional principle of PFC control method of the present invention and device circuit.
First embodiment have employed filter circuit and achieves PFC control method of the present invention and control device, under current detection circuit IA is operated in peakvalue's checking, also can be operated on mean value, correspondingly, the working method of comparator also needs adjustment, but this does not affect the working method of PFC control method of the present invention.The present invention also can adopt computing circuit to realize PFC control method of the present invention and device, as following second embodiment.
Second embodiment
Fig. 6 shows the theory diagram of the second embodiment, show the PFC device of application the inventive method, comprise: the rectifier bridge be made up of four rectifier diodes Da, Db, Dc, Dd, and the classical BoostPFC circuit topology that inductance L 1 and power tube Q1, diode D1, electric capacity C1 form; And feedback signal attenuation units 1/H, comparator unit, Current peak value detect circuit I A form current feedback part; Comparator unit also comprises built-in current error amplifier, pulse width modulator and driver etc., and belong to prior art, do not draw in Fig. 6, its load is the main power MOS pipe Q1 of a classical pfc circuit topology; Attenuation units 1/H inside also comprises built-in reference voltage and error amplifier, and also belong to prior art, do not draw in Fig. 6, the function of attenuation units is dividing potential drop, also makes voltage divider.Its control device adopts control method of the present invention to control, and forms attenuation units, subtraction amplifying circuit A5, PLL oscillating circuit, accurate full-wave rectifying circuit A3, voltage-controlled amplifier A1, summing circuit A2, multiplier M by resistance R1, R2, R3 and amplifying circuit A4.
Attenuation units is formed by resistance R1, R2, R3 and amplifying circuit A4, concrete connection is, resistance R1 is connected with two inlet wires of civil power respectively with one end of resistance R2, resistance R1 is connected with the other end of resistance R2, and be connected with resistance R3 one end, be connected to the input of amplifying circuit A4, the other end of resistance R3 is connected with the output negative of rectifier bridge simultaneously;
Amplifying circuit A4 is Linear Amplifer, exports half waveform WR1, and PLL oscillating circuit utilizes the phase place of half waveform WR1 to carry out pll oscillation, obtain standard, pure and civil power with the sinusoidal wave WS1 of homophase frequently, i.e. the first standard first-harmonic; Waveform WR1 and the first standard first-harmonic WS1 gives the subtraction circuit be made up of accurate full-wave rectifying circuit A3, subtraction amplifying circuit A5, obtains the first waveform WF1 by the output of subtraction amplifying circuit A5;
The operation principle of subtraction circuit: waveform WR1 is half-wave, and the first standard first-harmonic WS1 is sinusoidal wave, so, employ accurate full-wave rectifying circuit A3 and the first standard first-harmonic WS1 is rectified into half-wave, give subtraction amplifying circuit A5 again and carry out subtraction, obtain the distorted signal in industrial-frequency alternating current, i.e. the first waveform WF1; As the waveform of the some correspondence of WF1 indication in Fig. 6;
Obviously, the effective value of the first waveform WF1 and the ratio of the first effective value WR1 are distortion factor THD, adopt adder A2 that the first waveform WF1 and the second standard first-harmonic WS2 is added and obtain the second waveform WF2, the alternating current of the second standard first-harmonic WS2 and input is with frequency homophase, in figure 6, be the output half-wave acquisition of being amplified accurate full-wave rectifying circuit A3 by voltage-controlled amplifier A1.
When distortion factor THD is greater than the first limit value, the effective value of the second standard first-harmonic WS2 is zero, when the distortion factor is below the first limit value, the effective value of the second standard first-harmonic is inversely proportional to distortion factor THD, switch converters in PFC device, adopt current feedback technology, make the input current iL waveform of PFC device follow the absolute value of the second waveform WF2;
Utilize voltage-controlled amplifier A1 to realize above-mentioned functions in Fig. 6, when the effective value hour of the first waveform WF1 that subtraction amplifying circuit A5 exports, namely when the distortion factor is below the first limit value, the gain of voltage-controlled amplifier A1 is high; When the effective value of the first waveform WF1 that subtraction amplifying circuit A5 exports is large, when the distortion factor is greater than the first limit value, the gain of voltage-controlled amplifier A1 is extremely low, is even zero, and the second standard first-harmonic WS2 namely exported is zero;
Summing circuit A2 is added WF1 and WS2 and obtains the second waveform WF2, achieves WF2=WF1+WS2; Second waveform WF2 is signal Y simultaneously;
The output voltage Vo of PFC device, the i.e. terminal voltage of filter capacitor C1, through attenuation units 1/H internal circuit dividing potential drop, and and attenuation units 1/H inside reference voltage relatively after, input to the error amplifier process of attenuation units 1/H inside, obtain output voltage signal X;
Signal Y and above-mentioned output voltage signal X is added to the input of multiplier M jointly, the output Z=XY of multiplier M, the output Z of multiplier M is as the reference signal of Current Feedback Control, give comparator unit, after the switching current iS detected value exported with current detection circuit IA compares, built-in PWM and driver is added to through the current error amplifier that comparator is built-in, to control the break-make of main power MOS pipe Q1, thus make the second waveform WF2 that the waveform of input current (i.e. the electric current of inductance L 1) iL and summing circuit A2 export, namely Y waveform is basically identical.
Achieve when the civil power UAC wave distortion inputted is very little like this, mains waveform and Standard basis Bob comparatively after, the voltage of the first waveform WF1 obtained is close to zero, if do not take special measure, the current feedback technology of subsequent conditioning circuit directly cannot be followed the tracks of the first waveform WF1 and be carried out work.With summing circuit A2, the first waveform WF1 and the second standard first-harmonic WS2 addition is obtained the second waveform WF2, when the distortion factor is below the first limit value, the effective value of the second standard first-harmonic WS2 is inversely proportional to the distortion factor, namely the voltage of the first waveform is close to zero, namely the distortion factor is more close to zero, the effective value of the second standard first-harmonic is higher, like this, in the second waveform WF2 obtained, the composition of first-harmonic is more, switch converters in PFC device of the present invention, adopt current feedback technology, make the input current iL waveform of PFC device follow the second waveform WF2, i.e. signal Y.At this moment, along with the reduction of the distortion factor, control method of the present invention is more and more close to traditional PFC control effects.
As the operation principle in technical scheme, second embodiment of the invention achieves and detects, in the half-wave of alternating current voltage, when voltage is relatively high the distortion voltage waveform in power unit circuit, namely time relatively light by electric loading in supply line, realize the work of PFC device or current sinking larger; In the half-wave of alternating current voltage, when voltage is relatively low, when namely relatively weighing by electric loading in supply line, realizing PFC device current sinking is zero or less, achieves like this and corrects the overall PF value of power unit, the current harmonics of power unit entirety is greatly reduced, improve the input power factor of power unit, and, when the power factor of power unit itself is very high, control method of the present invention still can realize PFC device and work well, thus realizes goal of the invention.
Below be only the preferred embodiment of the present invention, it should be noted that, above-mentioned preferred implementation should not be considered as limitation of the present invention, for those skilled in the art, different sampling is added in the basic topology of circuit of the present invention, control strategy and current detecting strategy, the present invention can be optimized further in semi-load, power factor value under underloading, or directly use non-bridge PFC as main power topology, same use distorted signal controls pfc circuit, this for those skilled in the art, without departing from the spirit and scope of the present invention, some improvements and modifications can also be made, these improvements and modifications also should be considered as protection scope of the present invention, here no longer repeat by embodiment, protection scope of the present invention should be as the criterion with claim limited range.
Claims (9)
1. the PFC control method for PFC device, it is characterized in that, detect the input AC piezoelectric voltage waveform of PFC device input, and described input AC piezoelectric voltage waveform is decayed to without distortion the voltage waveform of the first effective value, the voltage waveform of the first described effective value and the first standard first-harmonic are carried out subtraction and obtains the first waveform, the effective value of described first standard first-harmonic equals the first described effective value and frequently homophase same with the voltage waveform of the first described effective value; The effective value of the first described waveform and the ratio of the first described effective value are the distortion factor; Adopt adder that the first described waveform and the second standard first-harmonic are added again and obtain the second waveform; The second described standard first-harmonic and described input AC electricity are with frequency homophase, and when the described distortion factor is greater than the first limit value, the effective value of the second described standard first-harmonic is zero; When the described distortion factor is below the first described limit value, the effective value of the second described standard first-harmonic is inversely proportional to the described distortion factor; Adopt Current feedback switch converters in described PFC device, make described PFC device input current waveform follow the absolute value of the second described waveform.
2. use a PFC control device for method described in claim 1, it is characterized in that, comprising:
One attenuation units, for decaying to the voltage waveform of the first effective value without distortion by described input AC piezoelectric voltage waveform;
One first standard first-harmonic generation unit, equals the first described effective value and first standard first-harmonic with frequency homophase electric with described input AC for generating an effective value;
One subtraction amplifying unit, for the voltage waveform of the first described effective value and the first described standard first-harmonic are carried out subtraction, obtains the first waveform;
One second standard first-harmonic generation unit, for generating and the second standard first-harmonic of described input AC electricity with frequency homophase, and when the distortion factor is greater than the first limit value, the effective value of the second described standard first-harmonic is zero; When the described distortion factor is below the first described limit value, the effective value of the second described standard first-harmonic is inversely proportional to the described distortion factor; The effective value of described first waveform and the ratio of described first effective value are the distortion factor;
One sum unit, obtains the second waveform for the first described waveform and the second described standard first-harmonic being added;
The absolute value of described second waveform follows value as the current feedback of control PFC device input current waveform; Namely PFC device input current waveform is made to follow the second described waveform absolute value.
3. PFC control device according to claim 2, is characterized in that, described attenuation units comprises attenuator, wave recovery unit; Described attenuator connects half waveform that input AC electricity exports through rectification, the alternating current of input is decayed to the first described effective value without distortion, and is inverted into normal sinewave output through described wave recovery unit Cycle by Cycle.
4. PFC control device according to claim 3, it is characterized in that, described first standard first-harmonic generation unit and described subtraction amplifying unit composition band stop filter, the band stop filter described in output access of described wave recovery unit, first-harmonic in the described wave recovery unit output waveform described in band stop filter filtering, first standard first-harmonic of described same frequency homophase is the virtual ripple of described band stop filter BEF filter unit, be the first-harmonic of industrial-frequency alternating current, the effective value of described virtual ripple equals the first described effective value WR1 automatically, the output of described band stop filter is the distorted waveform of industrial-frequency alternating current, be the first described waveform.
5. PFC control device according to claim 4, it is characterized in that, described second standard first-harmonic generation unit comprises amplitude limiter circuit, band pass filter and voltage-controlled amplifier, the amplitude limiter circuit described in output access of described wave recovery unit, first waveform described in control end access of described voltage-controlled amplifier; Described wave recovery unit output waveform after described amplitude limiter circuit, then obtains described second standard first-harmonic with frequency homophase electric with input AC through described band pass filter; The effective value of described second standard first-harmonic is through described voltage-controlled amplifier regulation output.
6. PFC control device according to claim 2, it is characterized in that, described attenuation units comprises resistance R1, resistance R2, resistance R3 and amplifying circuit A4, described resistance R1 is connected with two inlet wires of civil power respectively with one end of described resistance R2, described resistance R1 is connected with the other end of described resistance R2, and be connected with described resistance R3 one end, be connected to the input of described amplifying circuit A4, the other end of described resistance R3 is connected with the output negative of input AC electric rectification bridge simultaneously; Described amplifying circuit A4 exports half waveform decaying to the first described effective value without distortion.
7. PFC control device according to claim 6, it is characterized in that, described first standard first-harmonic generation unit comprises PLL oscillating circuit, half waveform that the described amplifying circuit A4 described in the access of PLL oscillating circuit exports, pll oscillation is carried out to the phase place of half described waveform, obtain and input the sine wave of civil power with frequency homophase, the first namely described standard first-harmonic.
8. PFC control device according to claim 7, is characterized in that, described subtraction amplifying unit comprises accurate full-wave rectifying circuit A3, subtraction amplifying circuit A5; An input of described subtraction amplifying circuit A5 is input to again after the described accurate full-wave rectifying circuit A3 described in the first standard first-harmonic access that described PLL oscillating circuit exports; The half-wave Waveform Input of the first described effective value that described amplifying circuit A4 exports is to another input of described subtraction amplifying circuit A5; The output of described subtraction amplifying circuit A5 obtains the first described waveform.
9. PFC control device according to claim 8, it is characterized in that, described second standard first-harmonic generation unit comprises voltage-controlled amplifier, the voltage-controlled amplifier input described in described first standard first-harmonic access after accurate full-wave rectifying circuit A3, first waveform described in control end access of described voltage-controlled amplifier, described in described voltage-controlled amplifier regulation output with the second standard first-harmonic of input civil power with frequently homophase, the effective value of the second standard first-harmonic is simultaneously through described voltage-controlled amplifier regulation output.
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| CN111934533B (en) * | 2020-07-15 | 2022-02-01 | 海信（山东）空调有限公司 | Voltage-multiplying rectification PFC circuit, control method thereof, storage medium and variable-frequency air conditioner |
| CN112269117A (en) * | 2020-10-01 | 2021-01-26 | 广东科学技术职业学院 | Distortion analysis method for amplifying circuit |
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| CN1109607A (en) * | 1993-06-25 | 1995-10-04 | 美国电报电话公司 | Circuit for estimating a peak or RMS value of a sinusoidal voltage waveform |
| EP0732797A1 (en) * | 1995-03-16 | 1996-09-18 | FRANKLIN ELECTRIC Co., Inc. | Power factor correction |
| 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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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1109607A (en) * | 1993-06-25 | 1995-10-04 | 美国电报电话公司 | Circuit for estimating a peak or RMS value of a sinusoidal voltage waveform |
| EP0732797A1 (en) * | 1995-03-16 | 1996-09-18 | FRANKLIN ELECTRIC Co., Inc. | Power factor correction |
| 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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