CN101022252A - High-power factor three-phase rectifier - Google Patents

Abstract

A three-phase rectifier of high power factor type is prepared as forming three-phase rectifying bridge by diodes as well as forming tertiary harmonic-wave current loop by two current-limiting diodes, two tertiary resonant inductances and five tertiary resonant capacities for realizing purpose of making harmonic wave content of input current be minimum.

Description

High-power factor three-phase rectifier

One, technical field

The present invention relates to a kind of three-phase rectifier, relate in particular to a kind of and existing three-phase rectifier and compare three-phase rectifier with high power factor.

Two, background technology

Three-phase not control rectifying circuit only needs to add that in DC side capacitor C or inductance capacitance LC filtering just can obtain good rectification characteristic, therefore obtain using comparatively widely because it is simple in structure.But three-phase not control rectifier Harmonics of Input content is big, and is still bigger to electrical network and contiguous power consumption equipment influence, is difficult to satisfy High Power Factor and Electro Magnetic Compatibility requirement.

The power factor that improves rectified three-phase circuit can adopt sinusoidal pulse width modulation PWM rectification or power factor correction APFC technology, has source technology can bring problems such as cost, reliability and high-frequency electromagnetic interference but adopt.Triple-frequency harmonics injection method based on passive techniques is another effective method that reduces Harmonics of Input.The triple-frequency harmonics injection method was proposed by B.M.Bird as far back as 1969, because the scheme that the initial stage proposes requires harsh, this method does not obtain people's attention, begin to have many scholars that it is studied again in the nineties in 20th century, research emphasis mainly concentrates on the realization of harmonic wave injection and the control of injection current size.Lifting the most representative several technical schemes below analyzes:

(1) scheme 1:Y/ Δ transformer and high-power resistance:

The main circuit topology of scheme 1 as shown in Figure 1.Triple harmonic current passes through resistance R ₁And Y/ Δ transformer injects ac input end, wherein injection current i _YSize and amplitude by DC side common-mode voltage and resistance R ₁Decision, the zero load of Y/ Δ transformer secondary is with injection current i _YDivide equally and inject three-phase input end respectively.

(2) scheme 2:LC resonance and simulative resistance circuit:

The circuit topology of scheme 2 as shown in Figure 2.S ₁, S ₂Be respectively LC resonant circuit and simulative resistance circuit.The simulative resistance circuit that is made of transformer and diode rectifier bridge can produce and the synchronous electric current of voltage on the former limit of transformer, and it acts on the resistance R of a kind of scheme ₁Identical.The LC resonant circuit is operated in resonant frequency point three times, and the filtering high order harmonic component makes injection current contain the harmonic wave beyond three times hardly.

(3) scheme 3: the simulative resistance circuit of bidirectional switch and band Single-phase PFC:

The circuit topology of scheme 3 as shown in Figure 3, wherein figure (a) is a main circuit, figure (b) injects the harmonic wave shaping network.This scheme and above two kinds of schemes are different, and triple-frequency harmonics is not to inject three-phase input end simultaneously, but the break-make by bidirectional switch, with this two diodes that link to each other during not conducting, inject triple-frequency harmonics mutually to this.Because no LC filtering in injection circuit, the harmonic current of injection also includes a large amount of high order harmonic components except that triple-frequency harmonics, must add Boost PFC and carry out shaping.

(4) scheme 4:Y/ Δ transformer and simulative resistance circuit:

The circuit topology of scheme 4 is the comprehensive of scheme 1 and scheme 2 as shown in Figure 4.

Such scheme can both reduce input current harmonics content, but has some shortcomings:

The shortcoming of scheme 1: Y/ Δ transformer efficiency is bigger, the corresponding increase of volume.Use the size of high-power resistance control harmonic current, loss is big, and the injection current size is almost constant, can not adapt to the variable power occasion.Because three/one-period of each rectifier diode conducting, rectifier output voltage is the three-phase line voltage envelope, and voltage ripple is big.

The shortcoming of scheme 2: though simulative resistance circuit can reduce the loss of infusion circuit, complex structure, and transformer voltage ratio fixes, and has the almost constant problem of injection current size equally.

The shortcoming of scheme 3: use two-way gate-controlled switch to solve and use the bulky problem of passive device, but need to add drive circuit, and simulative resistance circuit must be aided with the Boost pfc circuit, circuit structure complexity, reliability reduction.Output voltage connects identical with scheme 1, has the big shortcoming of output voltage ripple equally.

The shortcoming of scheme 4: its structure is the comprehensive of scheme 1 and scheme 2, has the part shortcoming of scheme 1 and scheme 2 equally.

Three, summary of the invention

1, technical problem: the technical problem to be solved in the present invention provides a kind of defective that can overcome above-mentioned available circuit existence, have that Harmonics of Input content is low, power factor is high, simple in structure, characteristics such as efficient is high, reliable operation, high-power converter is to the three-phase rectifier of electric network pollution in reducing.

2, technical scheme: to achieve these goals, technical solution of the present invention is: use LC resonance to inject the advantage that volume is little, higher harmonic content is low in the absorption scheme 2, in the control of injection current size, utilize diode current can not be negative characteristics, control the size of total triple harmonic current, and utilize electric capacity to shunt, make injection current inject input side, to reach the purpose that makes Harmonics of Input content minimum with optimal proportion.

Three-phase rectifier of the present invention comprises the three-phase commutation bridge that is made of diode, also comprise by two current limliting diodes, two three resonant inductances, five triple harmonic current loops that three resonant capacitances constitute, the negative electrode of wherein three diodes of three-phase commutation bridge is connected with the four or three resonant capacitance one end with the anode of the first current limliting diode respectively, the negative electrode of the first current limliting diode is connected with an end of first filter capacitor by the one or three resonant inductance, and the four or three time the resonant capacitance electric capacity other end is connected with the other end of first filter capacitor; The anode of other three diodes of three-phase commutation bridge is connected with the five or three resonant capacitance one end with the negative electrode of the second current limliting diode respectively, the anode of the second current limliting diode is connected with second filter capacitor, one end by second resonant inductance, and the five or three time the resonant capacitance other end is connected with the other end of second filter capacitor; The tie point of first, second and the three or three resonant capacitance is connected between the 4th, the 53 resonant capacitance and first, second filter capacitor simultaneously.

The first and second resonant inductance equal and opposite in directions and inductance value are L _I, the first to the 33 resonant capacitance equal and opposite in direction and capacitance are C _C, the 4th and the five or three resonant capacitance equal and opposite in direction and capacitance be C _NIf L _I/ 2=L, 3C _C+ 2C _N=C, then LC is operated in the resonance frequency place three times, produces triple harmonic current, i.e. 9 ω ²LC=1, wherein _ be the first-harmonic angular frequency.Two filter capacitor equal and opposite in directions, capacitance are C _O, and C _OMuch larger than C, triple-frequency harmonics is exerted an influence hardly.Two current limliting diode (D _O1, D _O2) playing restriction injection current size, the 4th and the 5th electric capacity plays shunting action, regulates the size of current of injecting the rectifier input.

3, beneficial effect: with respect to other existing schemes, power inverter of the present invention does not use complicated simulative resistance circuit, and structure is simplified, and loss is low.The harmonic wave injection current becomes fixed proportion with load, applicable to the unfixed occasion of load.Two resonant inductances can play the effect of output voltage filtering simultaneously, and output voltage ripple is low.

Four, description of drawings

Fig. 1 is the circuit topology schematic diagram of scheme 1;

Fig. 2 is the circuit topology schematic diagram of scheme 2;

Fig. 3 is the circuit topology schematic diagram of scheme 3, and wherein (a) is main circuit diagram, (b) for injecting the harmonic wave shaping network;

Fig. 4 is the circuit topology schematic diagram of scheme 4;

Fig. 5 is the high-power factor three-phase rectifier circuit diagram that injects based on triple-frequency harmonics of the present invention;

Fig. 6 is the working waveform figure of rectifier of the present invention;

Fig. 7 is THD and k relation curve schematic diagram;

Fig. 8 is a rectifier work wave under the actual conditions;

Fig. 9 is the schematic diagram that concerns of L and THD, cos  and PF;

Figure 10 is I _OThe schematic diagram that concerns with THD;

Figure 11-15 is a prototype test waveform schematic diagram;

Figure 16 is output voltage and load resistance relation curve schematic diagram;

Figure 17 is the efficiency curve schematic diagram.

Five, embodiment

As shown in Figure 5, the high-power factor three-phase rectifier of present embodiment comprises by diode D ₁, D ₂, D ₃, D ₄, D ₅, D ₆The three-phase commutation bridge that constitutes also comprises by current limliting diode D _O1, D _O2, three resonant inductance L ₁, L ₂, three resonant capacitance C _A, C _B, C _C, C _N1, C _N2The triple harmonic current loop that constitutes, diode D ₁, D ₃, D ₅Negative electrode respectively with the first current limliting diode D _O1Anode and the four or three resonant capacitance C _N1One end connects, the first current limliting diode D _O1Negative electrode by the one or three resonant inductance L ₁With the first filter capacitor C _O1An end connect the four or three resonant capacitance capacitor C _N1The other end and the first filter capacitor C _O1The other end connect; Diode D ₂, D ₄, D ₆Anode respectively with the second current limliting diode D _O2Negative electrode and the five or three resonant capacitance C _N2One end connects, the second current limliting diode D _O2Anode by the second resonant inductance L ₂With the second filter capacitor C _O2One end connects, the five or three resonant capacitance C _N2The other end and the second filter capacitor C _O2The other end connect; First, second and the three or three resonant capacitance C _A, C _B, C _CTie point be connected to resonant capacitance C simultaneously the 4th, the 53 time _N1, C _N2With first, second filter capacitor C _O1, C _O2Between.

Two three resonant inductance L ₁, L ₂Equal and opposite in direction and inductance value are L _I, three three resonant capacitance C _A, C _B, C _CEqual and opposite in direction and capacitance are C _C, the 4th and the five or three resonant capacitance C _N1, C _N2Equal and opposite in direction and capacitance are C _NIf L _I/ 2=L, 3C _C+ 2C _N=C, then LC is operated in the resonance frequency place three times, produces triple harmonic current, i.e. 9 ω ²LC=1, wherein _ be the first-harmonic angular frequency.Two filter capacitor C _O1, C _O2Equal and opposite in direction, capacitance are C _O, and C _OMuch larger than C, triple-frequency harmonics is exerted an influence hardly.Two current limliting diode D _O1, D _O2Play restriction injection current size, C _N1, C _N2Play shunting action, regulate the size of current of injecting the rectifier input.

For the operation principle of the high-power factor three-phase rectifier of making a concrete analysis of present embodiment, the purpose for easy analysis makes the following assumptions circuit:

1) output filter capacitor is enough big, output current I _OConstant;

2) inject harmonic current and ignore other harmonic wave in addition three times;

3) think capacitor C _A, C _B, C _CCapacitance very little, ignore the fundamental current that flows through it;

4) current i _CO1, i _CO2, i _CA, i _CB, i _CC, i _CN1, i _CN2Satisfy formula (1) relation.

$\left\{\begin{array}{c}{i}_{\mathrm{<figure-callout\; id="1"\; label="CO"\; filenames="A20061009726000141.png"\; state="\{\{state\}\}">CO</figure-callout>}1}=i_{\mathrm{<figure-callout\; id="2"\; label="CO"\; filenames="A20061009726000111.png,A20061009726000121.png"\; state="\{\{state\}\}">CO</figure-callout>}2}=i_1/2\\ i_{\mathrm{CA}}=i_{\mathrm{CB}}=i_{\mathrm{CC}}=i_C/3\\ i_{\mathrm{<figure-callout\; id="1"\; label="CN"\; filenames="A20061009726000141.png"\; state="\{\{state\}\}">CN</figure-callout>}1}=i_{\mathrm{<figure-callout\; id="2"\; label="CN"\; filenames="A20061009726000111.png,A20061009726000121.png"\; state="\{\{state\}\}">CN</figure-callout>}2}=i_{\mathrm{CN}}/2\end{array}\right.---\left(1\right)$

If i _IAmplitude is I _m, because LC satisfies three resonance, I under the ideal case _mShould be infinitely great, but because D _O1, D _O2Restriction, I _O+ i _I/ 2 can not be less than zero, so I _m=2I _OAs shown in Figure 6, i _IFor with common-mode voltage (v _H+ v _LThe synchronous sine wave in)/2, i.e. i _I=-2I _OCos3 ω t.

Definition k is harmonic wave injection rate, i.e. i _Cki _I, then

$\left\{\begin{array}{c}{i}_{\mathrm{CN}}=(1-k)i_1\\ i_{\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="A20061009726000141.png"\; state="\{\{state\}\}">D</figure-callout>}1}=I_O-k{\mathrm{<figure-callout\; id="3"\; label="I\; O\; cos"\; filenames="A20061009726000121.png"\; state="\{\{state\}\}">I</figure-callout>}}_O\cos 3\mathrm{\&omega;}\\ i_{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="A20061009726000111.png,A20061009726000121.png"\; state="\{\{state\}\}">D</figure-callout>}2}=I_O+k{\mathrm{<figure-callout\; id="3"\; label="I\; O\; cos"\; filenames="A20061009726000121.png"\; state="\{\{state\}\}">I</figure-callout>}}_O\cos 3\mathrm{\&omega;}\end{array}\right.---\left(2\right)$

Because the symmetry of three-phase system, the one-period with the A phase is divided into four-stage analysis herein.

I.[0，2π/3]

The diode D that this stage links to each other with A ₁Conducting, i _A=i _D1-i _CA

II.[2π/3，π]

Two not conductings of diode that this stage links to each other with A, i _A=-i _CA

III.[π，5π/3]

The diode D that this stage links to each other with A ₂Conducting, i _A=-i _D2-i _CA

IV.[5π/3，2π]

This stage and second stage situation are identical.

Can get A phase input current i thus _AExpression formula be:

$i_A=\left\{\begin{array}{c}{I}_O-\frac{k}{3}{\mathrm{<figure-callout\; id="3"\; label="I\; O\; cos"\; filenames="A20061009726000121.png"\; state="\{\{state\}\}">I</figure-callout>}}_O\cos 3\mathrm{\&omega;t},(0\&le;\mathrm{\&omega;t}<\frac{2}{3}\mathrm{\&pi;})\\ \frac{2k}{3}{\mathrm{<figure-callout\; id="3"\; label="I\; O\; cos"\; filenames="A20061009726000121.png"\; state="\{\{state\}\}">I</figure-callout>}}_O\cos 3\mathrm{\&omega;t},(\frac{2}{3}\mathrm{\&pi;}\&le;\mathrm{\&omega;t}<\mathrm{\&pi;},\frac{5}{3}\mathrm{\&pi;}\&le;\mathrm{\&omega;t}<2\mathrm{\&pi;})\\ -I_O-\frac{k}{3}{\mathrm{<figure-callout\; id="3"\; label="I\; O\; cos"\; filenames="A20061009726000121.png"\; state="\{\{state\}\}">I</figure-callout>}}_O\cos 3\mathrm{\&omega;t}(\mathrm{\&pi;}\&le;\mathrm{\&omega;t}<\frac{5}{3}\mathrm{\&pi;})\end{array}\right.$

To i _ACarry out fourier decomposition and know that it contains zero sequence odd harmonic in addition, and the amplitude I of nth harmonic _{A (n)}For:

$I_{A\left(n\right)}=\frac{4I_O}{\mathrm{\&pi;}}[\frac{\mathrm{kn}}{9-{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="A20061009726000111.png,A20061009726000121.png"\; state="\{\{state\}\}">n</figure-callout>}}^2}+\frac{1}{n}]\cos \frac{\mathrm{n\&pi;}}{6}---\left(4\right)$

Can draw THD shown in Figure 7 and the relation curve that changes with k by formula (4), as seen in the time of k=0.75, THD has minimum value, is about 5.08%.This moment C _A=C _B=C _C=0.25C, C _N1=C _N2=0.125C.

Above-mentioned analysis is carried out under ideal case, and under the actual conditions, except that k, other each parameters also can produce certain influence to the characteristic of rectifier, for the selection of passive device in the system, must take all factors into consideration various aspects such as performance, volume, cost.

In rectifier, inductance L ₁, L ₂Play simultaneously to output voltage filtering with to the effect of injection current filtering.

Because LC is operated in resonant frequency point three times, is not having D _O1, D _O2The time, i _IAmplitude is very big, I _L1, i _L2Have just have negative.D _O1, D _O2Play rectified action, inductance L ₁, L ₂Play filter action, when L hour, diode is long deadline, i _D1, i _D2The sine degree is low, Harmonics of Input content height.v _LO1, v _LO2As shown in Figure 8, output voltage V _OBe v _LO1-v _LO2DC component, visible V _OBe slightly larger than the output voltage V of the whole device of traditional three-phase _O', along with reducing of inductance value, output voltage values slightly increases.

Because C _A, C _B, C _CDirectly link to each other with the input major loop, can produce a fundamental current that is ahead of 90 ° of input phase voltages in electric capacity, current amplitude is V _m-C _C, must increase and increase with capacitance, wherein V _mBe input phase voltage amplitude.Promptly along with capacitance increases, the phase angle difference between input phase current and the phase voltage increases.

Fig. 9 is the relation curve of L and THD, cos  and power factor (PF), and the value of visible L is big more, and is favourable more to the performance of whole system, yet also can bring the drawback on volume and the cost, need take all factors into consideration.

For the rectifier output end difference mode signal, its output inductor, capacitance are respectively 4L, C _O/ 2, owing to be mainly fifth overtone in the difference mode signal except that DC component, definition d is the ratio of fifth overtone before fifth overtone and the filtering in the output voltage, and then d satisfies formula (5).Make that harmonic wave of output voltage content is less, then require d to approach 0.

$d=\frac{1}{\sqrt{{(1-72{\mathrm{\&omega;}}^{2}L{C}_O)}^2+{(24\mathrm{\&omega;L}/R)}^2}}---\left(5\right)$

C _O1, C _O2A main output voltage filter action, but they are also connected with the triple-frequency harmonics injection circuit simultaneously, very little for guaranteeing its influence to triple-frequency harmonics, C _OMust be much larger than C.

As seen from Figure 8, the size of load current also can influence diode D _O1, D _O2Deadline.When other conditions are constant, work as I _OMore little, diode D _O1, D _O2Deadline is long more, thereby causes the harmonic content in the input current also high more.

In side circuit, also also unsupported big more, the input current quality is high more, because line impedance R _LRestriction, i _IThe maximum of amplitude is:

$I_{m\left(\max \right)}=\frac{3\sqrt{3}{V}_m}{8\mathrm{\&pi;}{R}_L}---\left(6\right)$

Work as I _O＞I _{M (max)}/ 2 o'clock, with I _OIncrease, harmonic wave injection rate k departs from optimum value, and THD increases thereupon.

The increase of load current can cause the variation of input voltage, electric current phase angle difference simultaneously.When zero load, the input phase current only contains and flows through C _A, C _B, C _CFundamental current, so 90 ° of phase current leading phase voltages, along with the increase of load current, this phase angle difference constantly reduces, and approaches 0.

I _OWith the fundamental relation of THD, cos  as shown in figure 10, I wherein _ONBe nominal load current, as seen in very wide loading range, can both obtain higher power factor.

Because the rectifier line impedance can produce certain pressure drop, load current is more little, and this pressure drop is more little, and output dc voltage is high more.When zero load, rectifier is equivalent to the half bridge rectifier series connection of two three-phase capacitor filtering, and output voltage is the peak value of phase voltage envelope, i.e. 2V _m

Definition by power factor PF knows that PF is relevant with the phase angle difference  of THD and electric current and voltage, because THD is less to the influence of PF, considers with worst case (THD=15%), and PF=0.99cos  then, thus can get C _CSatisfy formula (6) relation.

$C_c=\frac{2P_O\mathrm{tg}\left[\arccos \left(1.01\mathrm{PF}\right)\right]}{3\mathrm{\&eta;}{{\mathrm{<figure-callout\; id="2"\; label="V\; m"\; filenames="A20061009726000111.png,A20061009726000121.png"\; state="\{\{state\}\}">V</figure-callout>}}_m}^2\mathrm{\&omega;}}---\left(7\right)$

Wherein η is the efficient of rectifier, P _OBe power output.According to preceding surface analysis, L, C satisfy formula (7) thereby the value of definite L, C as can be known.

$\left\{\begin{array}{c}C=\frac{3}{k}{C}_c\\ L=\frac{1}{9{\mathrm{\&omega;}}^{2}C}\end{array}\right.---\left(8\right)$

Output filter capacitor C _OMainly determine, because C by formula (5) _O＞＞C, then 72 ω ²LC _O＞＞1,72 ω ²LC _O＞＞24 ω L/R, C _OCan be approximately:

$C_O\&ap;\frac{1}{72{\mathrm{\&omega;}}^2\mathrm{Ld}}---\left(9\right)$

Test waveform (input voltage and input current and spectrum analysis thereof) when Figure 11-the 15th, the different loads of present embodiment, Figure 16 is output voltage curve, wherein R _N=150 Ω are the rated load impedance of rectifier, as seen when load variations, and the output voltage substantially constant.Because there is certain impedance in circuit, makes that the output voltage experimental result is more lower slightly than simulation result,

But still it is higher by about 5% than traditional three-phase rectifier.Harmonics of Input analysis result from figure, harmonic content is less.Figure 17 is an efficiency curve, and its efficient is higher as can be seen.

It is simple in structure that above test waveform has illustrated that the rectifier of present embodiment has, and efficient is higher, all has good harmonic suppression effect in than the heavy load scope, and output voltage is with the very little advantage of load variations.

Claims (2)

1, a kind of high-power factor three-phase rectifier comprises by diode (D ₁, D ₂, D ₃, D ₄, D ₅, D ₆) three-phase commutation bridge that constitutes, it is characterized in that, also comprise by current limliting diode (D _O1, D _O2), three resonant inductance (L ₁, L ₂), three resonant capacitance (C _A, C _B, C _C, C _N1, C _N2) the triple harmonic current loop that constitutes, diode (D ₁, D ₃, D ₅) negative electrode respectively with the first current limliting diode (D _O1) anode and the four or three resonant capacitance (C _N1) end connection, the first current limliting diode (D _O1) negative electrode by the one or three resonant inductance (L ₁) and the first filter capacitor (C _O1) an end connect the four or three resonant capacitance (C _N1) other end and the first filter capacitor (C _O1) the other end connect; Diode (D ₂, D ₄, D ₆) anode respectively with the second current limliting diode (D _O2) negative electrode and the five or three resonant capacitance (C _N2) end connection, the second current limliting diode (D _O2) anode by the second resonant inductance (L ₂) and the second filter capacitor (C _O2) end connection, the five or three resonant capacitance (C _N2) other end and the second filter capacitor (C _O2) the other end connect; First, second and the three or three resonant capacitance (C _A, C _B, C _C) tie point be connected to resonant capacitance (C simultaneously the 4th, the 53 time _N1, C _N2) and first, second filter capacitor (C _O1, C _O2) between.

2, high-power factor three-phase rectifier as claimed in claim 1 is characterized in that, three resonant inductance (L ₁, L ₂) equal and opposite in direction, three resonant capacitance (C _A, C _B, C _C) equal and opposite in direction, three resonant capacitance (C _N1, C _N2) equal and opposite in direction, filter capacitor (C _O1, C _O2) equal and opposite in direction.

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