CN103152931A - LED (light emitting diode) driving power supply with high power factor and without electrolytic capacity - Google Patents

Abstract

The invention relates to an LED (light emitting diode) driving power supply with a high power factor and without electrolytic capacity. The LED driving power supply mainly comprises an alternating current input power supply, a monophase uncontrolled rectifier bridge, a main DC (direct current)/DC conversion circuit, an auxiliary DC/DC conversion circuit, an energy storage capacitor and a filter capacitor. The LED driving power supply is mainly and technically characterized in that the auxiliary DC/DC conversion circuit is merged into the input end of the main DC/DC conversion circuit, and has the functions of balancing an instantaneous power between input and output to be without the electrolytic capacity and compensating a current wave shape on the input end to realize the high power factor. By the adoption of the driving power supply, the defect that a three-time harmonic wave injection method is limited by the power factor is made up, and a method of double frequency current wave shape fitting can be further adopted, thus the acquisition of a reference current wave shape is further simplified, and the controlling is facilitated. As a voltage ripple on the energy storage capacitor has no requirement, needed capacity values of the energy storage capacitor and the filter capacitor are extremely small, a film capacitor or a ceramic capacitor and the like can be directly adopted, the driving power supply has the advantages of long service life and the like, and is suitable for places of a public driving power supply of an LED with large power.

Description

A kind of High Power Factor LED driving power of no electrolytic capacitor

Technical field

The present invention relates to a kind of High Power Factor LED driving power of no electrolytic capacitor, belong to the A.C.-D.C. converter technical field in electrical energy changer.

Background technology

The advantages such as light-emitting diode (Lighting Emitting Diode, LED) belongs to solid-state cold light source, and it has, and energy-efficient, environmental protection, long-life, volume are little, safety, response are fast become the green illumination light source of a new generation.Along with the development of LED body and driving power technology, it has been widely used in the fields such as mobile phone, automobile, view, large-screen and military, home lighting, and it will eliminate other lighting source.The LED luminescent quality is determined by its average current and peak-to-average force ratio, so the driving power performance of LED seems most important, manufacturing high efficiency, High Power Factor, long-life driving power one-tenth key.The life-span of LED body reaches 100000 hours, and traditional LED driving power is to adopt circuit of power factor correction (Power Factor Correction, PFC) A.C.-D.C. converter, as shown in Figure 1, there is big capacity electrolyte capacitor in its output, its life-span is only several thousand hours, and 10 ℃ of every risings of temperature, its life-span reduces half, and the life-span utmost point of this and LED does not mate, and the volume of electrochemical capacitor is larger, also will affect the further raising of LED driving power power density.Therefore the High Power Factor driving power that develops the high-performance no electrolytic capacitor is the top priority that promotes that LED further promotes the use of.

In traditional pfc converter, suppose that power factor is 1, input current i _inWith supply voltage u _inWaveform be synchronous sine wave, the order

The instantaneous power p of power end input _inFor:

p _in＝u _in·i _in＝U _in·I _in·(1-cos2wt)

This moment input power p _inBe the square sine wave form, as shown in Figure 2.As realizing constant voltage when output, i.e. power output P _oConstant, the portion of energy that input power and power output differ from is all absorbed by output capacitance, therefore needs the larger electrochemical capacitor of employing capacity, and this is the basic reason that needs to adopt electrochemical capacitor.In order to solve the electrochemical capacitor problem in the LED driving power, mainly contain at present three kinds of methods, the one, the method for injection low-order harmonic, it is the method for mentioning in 200910027360.X as number of patent application, inject appropriate triple-frequency harmonics with the capacity of reduction output capacitance in input current, but the method can be subject to the restriction of input power factor; The 2nd, the output ripple current method is the method for mentioning in 201010568595.2 as number of patent application, and the method can effectively reduce the capacity of electric capacity, but pulsating current affects the life-span of LED and stroboscopic phenomenon can occur; The 3rd, additional branches method in pfc circuit, as the method for mentioning in number of patent application 201110457731.5, the method is effective to reducing the output capacitance capacity equally, but the limitation of existence, additional branches in anti-sharp pfc circuit has only been proposed, tool is not general, is not suitable for high-power LED driving power source.

Summary of the invention

1, goal of the invention

In order to overcome traditional LED driving power because of the major defect using electrochemical capacitor and can not be complementary with long-life LED and to solve the problem that the driving power performance is subjected to the power factor restriction, the invention provides a kind of new solution, not only need not electrochemical capacitor, and can also realize High Power Factor no electrolytic capacitor LED driving power that power factor is compensated.

2, technical scheme

For reaching above-mentioned goal of the invention, the High Power Factor LED driving power of no electrolytic capacitor of the present invention is characterized in that: comprise alternating current input power supplying u _in, single-phase rectifier bridge, main DC/DC translation circuit, auxiliary DC/DC translation circuit, filter capacitor and the storage capacitor do not controlled.

The function of wherein said main DC/DC translation circuit is in the situation that the no-output electrochemical capacitor, can provide constant output voltage or power for load, can be by injecting triple-frequency harmonics in the input current that is controlled at main DC/DC translation circuit, the purpose of injecting triple-frequency harmonics is only in order to solve the electrochemical capacitor problem of output, and need not consider the problem of power factor, and the function of described auxiliary DC/DC translation circuit is namely to eliminate to inject triple-frequency harmonics to the impact of input power factor.

The effect of wherein said auxiliary DC/DC translation circuit is that the input power of main DC/DC translation circuit is adjusted, with the instantaneous power between the input and output of balance master DC/DC translation circuit.As power supply input instantaneous power p _inGreater than the required firm power P of output _oThe time (p _in＞P _o), unnecessary power transfer is in auxiliary DC/DC translation circuit; As power supply input instantaneous power p _inLess than the required firm power P of output _oThe time (p _in＜P _o), not enough power is provided by auxiliary DC/DC translation circuit, and therefore auxiliary DC/DC translation circuit is the key of saving electrochemical capacitor, and the power of auxiliary DC/DC translation circuit is two-way flow simultaneously, thereby needs to adopt two-way DC/DC circuit.

Wherein said main DC/DC translation circuit, in order further to reduce the capacity of its output capacitance, the input current of controlling main DC/DC translation circuit is the alternating current component of two frequencys multiplication of DC component stack, and can minimumly according to power conservation and output capacitance capability value optimize the two best frequency multiplication alternating current component ratios that obtain, under the unity power factor situation that its effect that output capacitance capacity is reduced is only traditional LED driving power 39.1% of the output capacitance capacity.In order to guarantee High Power Factor, auxiliary DC/DC translation circuit compensates input current waveform, to obtain High Power Factor.Simultaneously by analysis, the input current of its auxiliary DC/DC translation circuit can come match with the superpose alternating current component of two frequencys multiplication of DC component, simplifying obtaining of reference current waveform, thereby simplifies the circuit of control section.

3, beneficial effect

Compared with prior art, technical characteristics of the present invention is that the application of auxiliary DC/DC translation circuit has generality, is not subjected to the restriction of physical circuit topology.Can effectively reduce the output capacitance capacity of main DC/DC translation circuit in order to replace electrochemical capacitor with non-electrolytic capacitor by auxiliary DC/DC translation circuit, and due to mains ripple no requirement (NR) on the output capacitance of auxiliary DC/DC translation circuit, thereby also can directly adopt non-electrolytic capacitor, realization obtains long-life driving power, auxiliary DC/DC translation circuit can compensate the current waveform of input simultaneously, thereby the impact that not required by power factor realizes High Power Factor, even unity power factor.Auxiliary DC/DC translation circuit carries out instantaneous power and power factor compensation at input, and is irrelevant with the load of driving power, and can realize very high power factor.The load end of the relative LED driving power in the position of auxiliary DC/DC translation circuit is the high-pressure side, thereby under the equal-wattage grade, less current value is arranged, so it is particularly suitable for the public adaptive driving power of a plurality of LED under large-power occasions, as shown in Figure 3.

Description of drawings

Fig. 1 is the circuit of power factor correction block diagram of traditional LED driving power;

Fig. 2 is input supply voltage, input current and input power in conventional P FC converter and the oscillogram of power output;

Fig. 3 is that the High Power Factor LED driving power of no electrolytic capacitor of the present invention is applied to the public adaptive driving power of n LED under large-power occasions, load end of the present invention access in parallel n current regulator (being comprised of Buck-1～Buck-n);

Fig. 4 is the High Power Factor LED driving power structured flowchart of no electrolytic capacitor of the present invention;

Fig. 5 is the High Power Factor LED driving power physical circuit exemplary plot of no electrolytic capacitor of the present invention, and wherein main DC/DC translation circuit adopts the Boost converter, and auxiliary DC/DC translation circuit adopts the Buck-Boost reversible transducer;

Fig. 6 is when injecting triple-frequency harmonics content I in the present invention ^* _g3Be respectively 0.5 and the main DC/DC translation circuit of 0.8 o'clock and the input current waveform of auxiliary DC/DC translation circuit;

Fig. 7 injects triple-frequency harmonics content I in main DC/DC translation circuit in the present invention ^* _g3With its output capacitance capacity E ^* _cBetween relation curve, curve table understand to inject the optimal value of triple-frequency harmonics content and the effect that the output capacitance capacity reduces;

Fig. 8 (a) is when main DC/DC translation circuit input power and power output Instantaneous equality and when constant, desirable input voltage u _gWith input current i _gWaveform; Fig. 8 (b) is the i that forms with two frequency multiplication alternating current components of DC component stack on Fig. 8 (a) basis _g+2Come the i of approximate ideal _gWaveform;

Fig. 9 works as main DC/DC translation circuit input current by i that two frequency multiplication alternating current components form of DC component stack in the present invention _g+2The time, input power p _inWith power output P _oRelation between waveform;

Figure 10 is two harmonic I in main DC/DC translation circuit input current in the present invention ^* _g2With output capacitance capacity E ^* _cRelation curve, curve table understands the optimal value of two harmonics in input current and the effect that the output capacitance capacity reduces;

Figure 11 is the single-phase current waveform of not controlling the rectification bridge output end Nodes, wherein i in the present invention _gBe the input current waveform of main DC/DC translation circuit, i _g1Be the single-phase output current wave of not controlling rectifier bridge, i _sIt is the input current waveform of auxiliary DC/DC translation circuit;

Figure 12 is the i that forms with two frequency multiplication alternating current components of DC component stack on the basis of Figure 11 in the present invention _{S_fit}Come the input current i of the former auxiliary DC/DC translation circuit of match _sWaveform.

Wherein, u _inBe input supply voltage; i _inBe net side input current; U _oBe output voltage; I _oOutput current; u _gBe the single-phase output voltage of not controlling rectifier bridge; i _gIt is the input current of main DC/DC translation circuit; p _inInput power; P _oPower output; i _g1Be the single-phase output current of not controlling rectifier bridge; i _sIt is the input current of auxiliary DC/DC translation circuit; U _sBe the output capacitance C of auxiliary DC/DC translation circuit _sUpper voltage; I ^* _g3Be to inject the content (representing with perunit value) of triple-frequency harmonics in main DC/DC translation circuit input current; E ^* _cBe output capacitance amount of capacity (representing with perunit value); i _g+2Be that main DC/DC translation circuit input current is (by DC component I _gavWith two harmonic I ^* _g2The approximate input current that forms); p _gIt is the instantaneous input power of main DC/DC translation circuit; I ^* _g2Be the approximate input current i of main DC/DC translation circuit _g+2In two harmonics sizes (representing with perunit value); i _{S_fit}It is the match electric current of auxiliary DC/DC translation circuit input current.All waveforms be all when the power supply fundamental frequency is 50Hz the base situation under gained.

Embodiment

Below in conjunction with accompanying drawing and specific embodiments, further illustrate the present invention, should understand these specific embodiments only is used for explanation the present invention and is not used in and limits the scope of the invention, after having read the present invention, those skilled in the art are to the modification of the various equivalent form of values of the present invention and be similar to LED driving power structured flowchart of the present invention and all fall within the application's claims limited range.

In order to understand content of the present invention and to be convenient to analytic explanation, make the following assumptions:

1. all devices are desirable device, without any loss;

2. switching frequency much larger than the fundamental frequency of power supply, can be ignored the high order harmonic component of being brought by the switching tube action.

Below in conjunction with drawings and Examples, technical scheme of the present invention is further described.The High Power Factor LED driving power structured flowchart of no electrolytic capacitor of the present invention as shown in Figure 4, it is characterized in that: its circuit structure block diagram is by alternating current input power supplying u _in, single-phasely do not control rectifier bridge (1), main DC/DC translation circuit (2), auxiliary DC/DC translation circuit (3), filter capacitor (4) and storage capacitor (5) forms.Main DC/DC translation circuit can adopt general DC-DC converter as previously mentioned, auxiliary DC/DC translation circuit needs to adopt the DC-DC converter of energy capable of bidirectional flowing, its concrete circuit topology does not limit, thereby has a generality, be illustrated in figure 5 as one of concrete implementing circuit example that adopts structured flowchart of the present invention, wherein main DC/DC translation circuit adopts booster converter (Boost circuit), and auxiliary DC/DC translation circuit adopts two-way Buck-Boost converter.

The present invention is auxiliary DC/DC translation circuit of additional access on the LED of conventional P FC driving power basis, this auxiliary DC/DC translation circuit has changed the working method of main DC/DC translation circuit, the main target of main DC/DC translation circuit is only turned to as load provides suitable power and output characteristic by power factor correction, and the function of auxiliary DC/DC translation circuit is: in time absorb and delivered power to realize no electrolytic capacitor, compensate the waveform shape of input current and realize High Power Factor.Auxiliary DC/DC translation circuit can compensate the triple harmonic current that main DC/DC translation circuit injects, and is subjected to the restriction of power factor with the content of eliminating its injection; The input current of main DC/DC translation circuit also can superpose two frequency multiplication alternating current components when controlling with DC component, same auxiliary DC/DC translation circuit compensates to obtain High Power Factor to current waveform, control for simplifying, the input current of auxiliary DC/DC translation circuit can come match with the DC component two frequency multiplication alternating current components that superpose.Below the operation principle of main DC/DC translation circuit and auxiliary DC/DC translation circuit is described in detail under two kinds of different mode of operations respectively.

1. the power factor when triple-frequency harmonics is injected in compensation

Can find out from the triple-frequency harmonics injection method, the factor that restriction output storage capacitor capacity reduces is the power factor of input.Inject the increase of content along with triple-frequency harmonics, output storage capacitor capacity is also along with minimizing, and power factor also descends simultaneously, therefore in the situation that do not take other any measures, there is limitation in the method, shows in Patents and document: when inject triple-frequency harmonics content be first-harmonic 48.4% the time, input power factor is just in time 0.9, reach IEC 61000-3-2 standard-required, and output storage capacitor capacity only is reduced to original 65.6%.In order further to reduce the capacity of output capacitance, need to increase the content that injects triple-frequency harmonics, the impact of power factor is compensated by the auxiliary DC/DC translation circuit shown in Figure 4 and 5.When the triple-frequency harmonics amplitude of injecting is I _g3, and first-harmonic content amplitude is I _g1, when triple-frequency harmonics content is expressed as I with perunit value ^* _g3, I ^* _g3For:

$I_{\mathrm{<figure-callout\; id="3"\; label="g"\; filenames="HSA00000857324100023.png"\; state="\{\{state\}\}">g</figure-callout>}3}^{*}=\frac{I_{g3}}{I_{g1}}---\left(1\right)$

In order to obtain High Power Factor (take unity power factor as example), the output current i of single-phase not control rectifier _g1For:

${\mathrm{<figure-callout\; id="1"\; label="i\; g"\; filenames="HSA00000857324100023.png"\; state="\{\{state\}\}">i</figure-callout>}}_g=\left|i_{\mathrm{in}}\right|=\sqrt{2}{I}_{\mathrm{in}}\left|\sin \left(\mathrm{wt}\right)\right|---\left(2\right)$

Can draw the input current i of auxiliary DC/DC translation circuit according to the KCL theorem of circuit node _sFor:

$i_s=i_{g1}-i_g=\sqrt{2}{I}_{\mathrm{in}}\left|\sin \left(\mathrm{wt}\right)\right|-|I_{\mathrm{<figure-callout\; id="1"\; label="g"\; filenames="HSA00000857324100023.png"\; state="\{\{state\}\}">g</figure-callout>}1}\sin \left(\mathrm{wt}\right)+{\mathrm{<figure-callout\; id="3"\; label="I\; g"\; filenames="HSA00000857324100023.png"\; state="\{\{state\}\}">I</figure-callout>}}_g^3\&CenterDot;{\mathrm{<figure-callout\; id="1"\; label="I\; g"\; filenames="HSA00000857324100023.png"\; state="\{\{state\}\}">I</figure-callout>}}_g\sin \left(3\mathrm{wt}\right)|---\left(3\right)$

Its relevant waveform has provided respectively I as shown in Figure 6 in figure ^* _g3=0.5 and I ^* _g3The main DC/DC translation circuit of=0.8 o'clock and the input current waveform of auxiliary DC/DC translation circuit.As long as the input current waveform of main DC/DC translation circuit and auxiliary DC/DC translation circuit is controlled to be as shown in Figure 6, can realizes no electrolytic capacitor and unity power factor.The method can be eliminated the interaction relation of injecting triple-frequency harmonics content and input power factor, therefore can will reduce the capacity of output capacitance as an only optimization aim, can draw best injection triple-frequency harmonics content, through can be calculated the relation curve that injects between triple-frequency harmonics content and minimizing output capacitance capacity as shown in Figure 7, get best injection triple-frequency harmonics content I ^* _g3=0.52, this moment E ^* _c=64.72%, show 64.72% when the output capacitance capacity can be reduced to unity power factor, can find out and can realize High Power Factor under the condition that has auxiliary DC/DC translation circuit, and the output capacitance capacity also can further reduce.And when inject simultaneously five or during the seventh harmonic effect more obvious.

2. DC component stack two harmonic matches

When the input power of analysis conventional unity power factor circuit (as shown in Figure 1) and power output, the single-phase output voltage u of not controlling rectifier bridge _gBe the steamed bun ripple, if power output is when being constant value, can draw the single-phase output current of not controlling rectifier bridge is i _gExpression formula as shown in the formula shown in (4), its current waveform is as shown in Figure 8.

$i_g=\frac{P_o}{u_g}=\frac{P_o}{\left|\sqrt{2}{U}_{\mathrm{in}}\sin \left(\mathrm{wt}\right)\right|}---\left(4\right)$

If control the input current waveform of main DC/DC translation circuit as shown in Fig. 8 (a), through can be calculated its input power factor close to 0, although can compensate power factor by auxiliary DC/DC translation circuit, but its input current waveform is special and have an infinitely large quantity, therefore can't realize easily, only seek its method with input power and the power output of balance master DC/DC translation circuit as far as possible effectively.To desirable input current waveform i _gTherefore analyze and can get, the frequency of its waveform is two times of supply frequencies, controls and obtain reference current waveform for convenient, can be similar to by DC component two harmonics that superpose, and as shown in Fig. 8 (b), the i that it is approximate _g+2Expression formula is shown below.

$i_{g+2}\left(t\right)=I_{\mathrm{gav}}+I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*}{I}_{\mathrm{gav}}\sin (2\mathrm{wt}+\mathrm{\&pi;}/2)---\left(5\right)$

The DC component of wherein, establishing main DC/DC translation circuit input current is I _gav, the amplitude of the second harmonic component of injection is I _g2, I wherein ^* _g2Be I _g2Perunit value, I ^* _g2=I _g2/ I _gav

Due to two harmonics in the input current approximate waveform and the output voltage u of not controlling rectifier bridge _gThere is same frequency, therefore can produces active power.In order to make power output constant, approximate input current waveform i _g+2Should satisfy corresponding power conservation law.Therefore can draw the expression formula of following power conservation.

$P_o=\frac{1}{0.01}{\&Integral;}_0^{0.01}{p}_m\left(t\right)\mathrm{dt}=\frac{1}{0.01}{\&Integral;}_0^{0.01}{i}_{g+2}\left(t\right)\&CenterDot;u_g\left(t\right)\mathrm{dt}$ (6)

$=\frac{1}{0.01}{\&Integral;}_0^{0.01}(I_{\mathrm{gav}}+I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*}\&CenterDot;I_{\mathrm{gav}}\sin (2\mathrm{wt}+\mathrm{\&pi;}/2))\&CenterDot;\left(\sqrt{2}{U}_{\mathrm{in}}\sin \left(\mathrm{wt}\right)\right)\mathrm{dt}$

Abbreviation can draw:

$P_o\&ap;(0.9-0.3\&times;I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*})\&CenterDot;I_{\mathrm{gav}}\&CenterDot;U_{\mathrm{in}}---\left(7\right)$

The main DC/DC translation circuit input current that is similar to DC component stack two harmonics can draw the instantaneous input power of main DC/DC translation circuit, instantaneous input power p _gWith constant power output P _oRelation as shown in Figure 9.

Are instantaneous powers of balance input and output as far as possible effectively with the effect of DC component stack two harmonics, therefore need to calculate the DC component I of best input current _gavWith two harmonic I ^* _g2By the DC component I to input current _gavWith two harmonic I ^* _g2The condition of carrying out and border limit, and optimization aim is to reduce the size of output capacitance capacity, and this is directly relevant to the area that the input-output power waveform encloses.Therefore setting up the mathematics optimal models is shown below

$\min E_c=\frac{1}{2}\&times;{\&Integral;}_0^{0.01}|\sqrt{2}{U}_{\mathrm{in}}\sin \left(\mathrm{wt}\right)\&CenterDot;\{I_{\mathrm{gav}}+I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*}\&CenterDot;I_{\mathrm{gav}}\sin (2\mathrm{wt}+\mathrm{\&pi;}/2)\}-P_o|\mathrm{dt}$

$s.t.\left\{\begin{array}{c}{I}_{\mathrm{gav}}>0\\ I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*}>0\\ P_o\&ap;(0.9-0.3\&times;I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*})\&CenterDot;I_{\mathrm{gav}}\&CenterDot;U_{\mathrm{in}}\end{array}\right.---\left(8\right)$

Wherein, E _cBe the energy that the needs on output capacitance store, directly reflect the size of output capacitance capacity, represent for convenience magnitude relationship, with E _cBe converted into perunit value E ^* _cThrough can be calculated two harmonic I ^* _g2With output capacitance capacity E ^* _cRelation, as shown in figure 10.Can draw from figure and work as I ^* _g2=0.482 o'clock, the energy on output capacitance had minimum value, and 39.1% in the time of being reduced to unity power factor can be found out the capacity that can obviously reduce output capacitance, than injecting the triple-frequency harmonics method, better effect was arranged.

With the electric current of the DC component stack two harmonics input current as main DC/DC translation circuit, in the situation that do not adopt other measure, it will inevitably affect input power factor.Therefore need to adopt auxiliary DC/DC translation circuit that input current and power factor are compensated.

When being in unity power factor situation lower time, the desirable rectifier bridge output current i of not controlling _g1Waveform be the steamed bun ripple.Therefore draw the input current i of compensation DC/DC circuit according to the KCL theorem of Nodes _sFollowing expression is arranged:

$i_s=i_{g1}-i_g=i_{g1}-i_{g+2}$ (9)

$=\sqrt{2}{I}_{\mathrm{in}}\left|\sin \left(\mathrm{wt}\right)\right|-(I_{\mathrm{gav}}+I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*}{I}_{\mathrm{gav}}\sin (2\mathrm{wt}+\mathrm{\&pi;}/2))$

The single-phase current waveform of not controlling the rectification bridge output end Nodes can draw the input current i of auxiliary DC/DC translation circuit as shown in figure 11 from Figure 11 and Shi (9) _sAlthough waveform obtained by trigonometric function, the acquisition that its reference current waveform can't be easy.But can draw input current i _sWaveform obviously have DC component and two harmonics, therefore can come the input current i of the auxiliary DC/DC translation circuit of match with DC component two harmonics that superpose _sWaveform.If input current i _sFitting expression be i _{S_fit}, wherein DC component is I _sav, the amplitude of two harmonics is I _s2Represent

i _{s_fit}＝I _sav+I _s2sin(2wt-π/2) (10)

The input current i of match _{S_fit}Waveform as shown in figure 12.Because auxiliary DC/DC translation circuit does not exist power consumption without part, so the active power of its input should be zero, can get:

$P_{s\_\mathrm{in}}=\frac{1}{0.01}{\&Integral;}_0^{0.01}\sqrt{2}{U}_{\mathrm{in}}\sin \left(\mathrm{wt}\right)\&CenterDot;\{I_{\mathrm{sav}}+I_{s2}\sin (2\mathrm{wt}-\mathrm{\&pi;}/2)\}\mathrm{dt}=0---\left(11\right)$

Abbreviation gets:

P _{s_in}≈0.3I _s2·U _in+0.9I _sav·U _in＝0 (12)

In order to obtain best fitting effect, the final purpose of match is to obtain High Power Factor, thereby best effect is that total percent harmonic distortion of power end input current is minimum, the input current i of the power end that obtains after over-fitting _inFor:

$i_{\mathrm{in}}=\mathrm{sign}\left(\sin \left(\mathrm{wt}\right)\right)\&CenterDot;i_{\mathrm{<figure-callout\; id="1"\; label="g"\; filenames="HSA00000857324100023.png"\; state="\{\{state\}\}">g</figure-callout>}1}=\mathrm{sign}\left(\sin \left(\mathrm{wt}\right)\right)\&CenterDot;(i_{g+2}+i_{s\_\mathrm{fit}})$ (13)

$=\mathrm{sign}\left(\sin \left(\mathrm{wt}\right)\right)\&CenterDot;(I_{\mathrm{gav}}+I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*}{I}_{\mathrm{gav}}\sin (2\mathrm{wt}+\mathrm{\&pi;}/2)+I_{\mathrm{sav}}+I_{s2}\sin (2\mathrm{wt}-\mathrm{\&pi;}/2))$

Therefore with the input current i of power end _inTotal percent harmonic distortion minimum be optimization aim, simultaneously to carrying out I _savAnd I _s2Condition and border limit, and can set up the mathematics optimal models, to obtain most suitable I _savAnd I _s2Obtain the reference current waveform of auxiliary DC/DC translation circuit input current.

$\min \mathrm{THD}\left(i_{\mathrm{in}}\right)=\mathrm{THD}(\mathrm{sign}\left(\sin \left(\mathrm{wt}\right)\right)\&CenterDot;(I_{\mathrm{gav}}+I_{\mathrm{<figure-callout\; id="2"\; label="g"\; filenames="HSA00000857324100032.png,HSA00000857324100042.png"\; state="\{\{state\}\}">g</figure-callout>}2}^{*}{I}_{\mathrm{gav}}\sin (2\mathrm{wt}+\mathrm{\&pi;}/2)+I_{\mathrm{sav}}+I_{s2}\sin (2\mathrm{wt}-\mathrm{\&pi;}/2)))$

$s.t.\left\{\begin{array}{c}{I}_{s2}>0\\ 0.3I_{s2}\&CenterDot;U_{\mathrm{in}}+0.9I_{\mathrm{sav}}\&CenterDot;U_{\mathrm{in}}=0\end{array}\right.---\left(14\right)$

Claims (5)

1. the High Power Factor LED driving power of a no electrolytic capacitor, is characterized in that: comprise input ac power u _in, single-phase rectifier bridge (1), main DC/DC translation circuit (2), auxiliary DC/DC translation circuit (3), filter capacitor (4) and the storage capacitor (5) do not controlled.Main DC/DC translation circuit (2) is connected with the single-phase output of not controlling rectifier bridge (1) with auxiliary DC/DC translation circuit (3) is in parallel, the effect of filter capacitor (4) is only the harmonic wave at filtering switching frequency place, and the mains ripple no requirement (NR) of storage capacitor (5), thereby filter capacitor (4) and storage capacitor (5) can adopt non-electrolytic capacitor, as thin-film electro ceramic condenser etc. perhaps.

2. the High Power Factor LED driving power of no electrolytic capacitor according to claim 1, it is characterized in that: auxiliary DC/DC translation circuit (3) access place is positioned at single-phase the control between rectifier bridge (1) and main DC/DC translation circuit (2), the power of inputting main DC/DC translation circuit (2) is adjusted, with the power between the balance input and output, therefore the power of auxiliary DC/DC translation circuit (3) is two-way flow, needs to adopt two-way DC/DC translation circuit.

3. the High Power Factor LED driving power of no electrolytic capacitor according to claim 2, be further characterized in that: when the circuit of power factor correction employing of traditional no electrolytic capacitor is injected three times (or five times, seven times) when Harmonic Method reduces the output capacitance of pfc circuit, can carry out current waveform by the waveform that additional auxiliary DC/DC translation circuit (3) is controlled its input current and compensate to overcome the power factor restriction that the harmonic method is brought, to obtain the effect of High Power Factor.

4. the High Power Factor LED driving power of no electrolytic capacitor according to claim 2, be further characterized in that: the input current that can control main DC/DC translation circuit (2) is the alternating current component of two frequencys multiplication of stack on DC component, can realize that equally the degree of unbalance between input-output power reduces, thereby reduce the capacity of output capacitance, can be reduced in theory 39.1% in traditional unity power factor situation.

5. the High Power Factor LED driving power of no electrolytic capacitor according to claim 4, it is characterized in that: auxiliary DC/DC translation circuit (3) compensates the input current waveform of main DC/DC translation circuit (2), to obtain High Power Factor, input current waveform for auxiliary DC/DC translation circuit (3) can come match with the alternating current component of two frequencys multiplication of stack on DC component, to simplify the acquisition of reference current waveform, simplified control circuit.

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