CN101860192A - Three-state three-level PFC circuit and multi-state three-level PFC circuit - Google Patents

Abstract

The invention relates to a three-state three-level PFC circuit, which comprises an inductor, a combined three-state switch, a first capacitor and a second capacitor. The inductor is connected between a first end of an AC power supply and a first end of the combined three-state switch; a second end of the combined three-state switch is connected at a first end of the first capacitor; a third end of the combined three-state switch is connected at a second end of the second capacitor; a fourth end of the combined three-state switch is grounded; and the first end of the first capacitor, a second end of the first capacitor, and the second end of the second capacitor output three-level voltage. The invention also provides a multi-state three-level PFC circuit correspondingly. Compared with the common circuit without a three-state switch or a multi-state switch, the PFC circuit provided by the invention can obviously reduce the dimensions of the inductor and the capacitors, improve the power factor of the circuit simultaneously and reduce the total harmonic content on the premise of maintaining the switch frequency and ripples on a passive device invariable, and can reduce the switch frequency and obviously improve the circuit efficiency on the premise of maintaining the input current ripple frequency and magnitude invariable.

Description

A kind of ternary three-level PFC circuit and polymorphic three-level PFC circuit

Technical field

The present invention relates to electronic technology field, more particularly, relate to a kind of ternary three-level PFC circuit and polymorphic three-level PFC circuit.

Background technology

High frequency switch power is extensively in different occasions, as needing supply voltage is transformed to another required voltage grade from an electric pressure under a lot of application conditions.In the converting system of this AC-to DC (AC/DC), realize desired voltage conversion function except needs, also need to satisfy various standards to power factor (Power Factor, PF), total harmonic distortion (Total Harmonics Distortion, THD) and the requirement of electromagnetic interference EMI (Electromagnetic Interference).

See also Fig. 1, be a kind of three-level PFC circuit.As shown in Figure 1, first end ofinductance L 1 links to each other with AC power first end, second end ofinductance L 1 links to each other with thefirst input end 101 of bridge arm circuit, in bridge arm circuit,first input end 101 is connected tofirst output 103 by the diode D1 of forward,first input end 101 also is connected tosecond output 104 by reverse diode D2,first output 103 is bycapacitor C 1 ground connection,second output 104 is bycapacitor C 2 ground connection,first input end 101 also by differential concatenation two switching tube Q1 and Q2 be connected tosecond input 102, and second input end grounding and be connected to AC power second end.This circuit when switching tube Q1 and Q2 open, electric current two switching tubes of flowing through; And when switching tube turn-offs, electric current flow through a diode D1 or D2, it is half of traditional two level topologys that the characteristic of three level makes the sensibility reciprocal of inductance, thereby can be than two level PFCs (Power Factor correction, power factor correction) the circuit inductance size is little, the voltage stress of switching tube is half of traditional two level, so can reduce the switching loss of semiconductor device, improves circuit efficiency.

Yet along with the continuous increase of high power density high performance-price ratio product demand, switching frequency improves constantly to reduce the volume of passive device, is difficult to guaranteed efficiency so again.So, still need to develop a kind of pfc circuit and realize raising the efficiency simultaneously purpose with power density.

Summary of the invention

The technical problem to be solved in the present invention is, can not raise the efficiency defective with power density simultaneously at existing pfc circuit above-mentioned, and a kind of ternary three-level PFC circuit and polymorphic three-level PFC circuit are provided.

The technical solution adopted for the present invention to solve the technical problems is: construct a kind of ternary three-level PFC circuit, comprising: inductance, compound tri-state switch, first electric capacity and second electric capacity;

Described inductance is connected between AC power first end and compound tri-state switch first end, compound tri-state switch second end is connected first end of first electric capacity, compound tri-state switch the 3rd end is connected second end of second electric capacity, compound tri-state switch the 4th end ground connection, second end of first end of first electric capacity, second end of first electric capacity and second electric capacity is exported three level voltages.

In ternary three-level PFC circuit of the present invention, described compound tri-state switch comprises:

Second tri-state switch of working when first tri-state switch of working when the AC power input signal is in positive half period and AC power input signal are in negative half-cycle.

In ternary three-level PFC circuit of the present invention, described first tri-state switch comprises:

Transformer, the end of the same name on the former limit of described transformer and the different name end of secondary link to each other as first end of compound tri-state switch;

Two first diodes and two switching tubes; The anode of two first diodes is connected to the different name end on former limit of transformer and the end of the same name of secondary respectively, and the negative electrode of two first diodes all links to each other with first end of first electric capacity; First switching tube is connected across between the different name end and ground on former limit of transformer, and second switching tube is connected across between the end of the same name and ground of secondary of transformer.

In ternary three-level PFC circuit of the present invention, described compound tri-state switch also comprises: two second diodes; The negative electrode of two second diodes is connected to the different name end on former limit of transformer and the end of the same name of secondary respectively, the anode of two second diodes all links to each other with second end of second electric capacity, and described transformer, two switching tubes and described two second diodes constitute second tri-state switch.

The present invention also provides a kind of polymorphic three-level PFC circuit, and described polymorphic three-level PFC circuit comprises: inductance, compound polymorphic switch, first electric capacity and second electric capacity;

Described inductance is connected between AC power first end and compound polymorphic switch first end, compound polymorphic switch second end is connected first end of first electric capacity, compound polymorphic switch the 3rd end connects second end of second electric capacity, compound polymorphic switch the 4th end ground connection, second end of first end of first electric capacity, second end of first electric capacity and second electric capacity is exported three level voltages.

In polymorphic three-level PFC circuit of the present invention, described compound polymorphic switch comprises:

The second polymorphic switch of working when first polymorphic switch of working when the AC power input signal is in positive half period and AC power input signal are in negative half-cycle.

In polymorphic three-level PFC circuit of the present invention, the described first polymorphic switch comprises:

Transformer with N winding, wherein N is the integer greater than 2, and a secondary N winding of described transformer is linked to be equilateral polygon, and the end of the same name of a former limit N winding of described transformer links to each other as compound polymorphic switch first end;

The N that links to each other with the different name end of the former limit N winding of transformer organizes first diode and switching tube respectively, wherein the anode of N first diode is connected to the different name end of a former limit N winding of transformer respectively, and the negative electrode of N first diode links to each other with first end of first electric capacity; N switching tube is connected across respectively between the different name end and ground of a former limit N winding of transformer.

In polymorphic three-level PFC circuit of the present invention, described compound polymorphic switch also comprises: N second diode; The negative electrode of described N second diode is connected to the different name end of a former limit N winding of transformer respectively, and the anode of N second diode links to each other with second end of second electric capacity; Described transformer, a described N switching tube and described N second diode constitutes the second polymorphic switch.

Implement ternary three-level PFC circuit of the present invention and polymorphic three-level PFC circuit, have following beneficial effect:

1, the present invention has constructed a kind of ternary three-level PFC circuit by adopting compound tri-state switch, and the turn-on and turn-off by PWM modulates the control switch pipe just can realize the output of different modalities.The input current of ternary three-level PFC circuit provided by the invention is less than the input current of traditional three-level PFC, and as seen its circuit efficiency is higher.If keep identical inductive current ripple size and frequency, the switching frequency of the ternary three-level PFC of the present invention is half of common three level, thereby makes the switching frequency of polymorphic three-level PFC reduce, and corresponding efficient improves.

2, the inductance of ternary three-level PFC provided by the invention is withstand voltage is half of traditional three-level PFC, and like this under the identical situation of other conditions, its inductance value can be half of traditional three-level PFC, and the inductance volume also reduces.

The inductive current ripple of the ternary three-level PFC that 3, provides simultaneously has more ripples in the same cycle be zero point, reduced the switching loss and the on-state loss of power switch pipe, and this also is of value to the PF value that improves circuit and reduces THD.

4, the present invention's a kind of polymorphic three-level PFC circuit that also adopted compound polymorphic switch structure, compare it with traditional circuit and have above-mentioned characteristic equally, if promptly the size of constant inductance of size of the ripple on maintained switch frequency and the passive device and electric capacity can significantly reduce, the power factor of circuit improves simultaneously, and total harmonic distortion reduces; If keep input current ripple frequency and size constant then can reduce switching frequency, significantly improve the efficient of circuit.

Description of drawings

The invention will be further described below in conjunction with drawings and Examples, in the accompanying drawing:

Fig. 1 is existing three-level PFC circuit schematic diagram;

Fig. 2 (a) is respectively the structural representation of tri-state switch, four attitude switches and five attitude switches to Fig. 2 (c);

Fig. 3 (a) is respectively the operation mode figure of tri-state switch to Fig. 3 (d);

Fig. 4 (a) is respectively the operation mode figure of four attitude switches to Fig. 4 (h);

Fig. 5 is the circuit theory diagrams of ternary three-level PFC circuit first preferred embodiment of the present invention;

Fig. 6 is the circuit theory diagrams of ternary three-level PFC circuit second preferred embodiment of the present invention;

Fig. 7 (a) is respectively the working mode figure of ternary three-level PFC circuit in the preferred embodiment of the present invention to Fig. 7 (d);

Fig. 8 is four attitude three-level PFC circuit schematic diagrams in the preferred embodiment of the present invention;

Fig. 9 (a) and Fig. 9 (b) are respectively the output voltage waveform of traditional circuit and circuit of the present invention;

Figure 10 (a) and Figure 10 (b) are respectively the input current waveform figure of traditional circuit and circuit of the present invention;

Figure 11 (a) and Figure 11 (b) are respectively the drive signal waveform figure of traditional circuit and circuit of the present invention;

Figure 12 (a) and Figure 12 (b) are respectively traditional circuit and circuit inductance current ripples figure of the present invention;

Figure 13 (a) and Figure 13 (b) are respectively traditional circuit and circuit inductance voltage oscillogram of the present invention;

Figure 14 (a) and Figure 14 (b) are respectively traditional circuit and circuit inductance current waveform figure of the present invention;

Figure 15 (a) is respectively the inductive current ripple figure of circuit of the present invention when the different duty to Figure 15 (c);

Figure 16 (a) and Figure 16 (b) are respectively traditional circuit and circuit of the present invention voltage oscillogram at switching tube group two ends, and Figure 16 (c) is the voltage oscillogram of circuit transformer front end of the present invention with ground.

Embodiment

In order to make purpose of the present invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with drawings and Examples.

The present invention has mainly realized ternary or polymorphic tri-level circuit output with tri-state switch and polymorphic switch application in pfc circuit.Definition to polymorphic switch describes below.See also Fig. 2 (a) to Fig. 2 (c), be respectively the structural representation of tri-state switch, four attitude switches and five attitude switches.The brachium pontis that the structure that realizes polymorphic switch needs a transformer and one to be made up of switching tube etc.Shown in Fig. 2 (a), if there are two windings on the former limit of transformer, then switching tube is two brachium pontis structures, and what realized is tri-state switch; Shown in Fig. 2 (b), if there are three windings on former limit, then switching tube is three brachium pontis structures, realization be four attitude switches; Shown in Fig. 2 (c), if there are four windings on former limit, then switching tube is four brachium pontis structures, realization be five attitude switches.By that analogy, when there is the individual winding of N (N 〉=2) on the former limit of transformer, then switching tube is a N brachium pontis structure, realization be (N+1) attitude switch.

To the structure shown in Fig. 2 (c), diode can replace with switching tube at Fig. 2 (a).The difference of two kinds of structures is can only one-way flow with diode current; Can two-way flow with the switching tube electric current, therefore can be used in all-wave power factor correction and the inverter circuit.See also Fig. 3 (a) to Fig. 3 (d), be respectively the operation mode figure of tri-state switch.To the tri-state switch shown in Fig. 3 (d), adopt switching tube to replace diode at Fig. 3 (a).Conducting state shown in Fig. 3 (a) and Fig. 3 (b) (promptly going up pipe and a pipe conducting simultaneously down for one) has constituted first kind of state of tri-state switch, when using at ternary three-level PFC circuit just correspondence first mode.Correspondingly, conducting state shown in Fig. 3 (c) and Fig. 3 (d) is corresponding respectively second kind of state of tri-state switch (going up pipe conducting simultaneously for two) and the third state (two pipe conductings simultaneously down), promptly when being applied in ternary three-level PFC circuit just correspondence second mode and the 3rd mode.In above-mentioned tri-state switch, an end of the same name of transformer links to each other with a different name end, and the electric current that flows into two brachium pontis like this equates.Because the different conductings of four switching tubes have constituted three kinds of operating states, this also is the principle of tri-state switch name.

See also Fig. 4 (a) to Fig. 4 (h), be respectively the operation mode figure of four attitude switches.To shown in Fig. 4 (h), the secondary of transformer is linked to be triangular structure as Fig. 4 (a), does the electric current that can make in three windings in former limit like this and equates that operation principle is similar to tri-state switch.Wherein, Fig. 4 (a) to Fig. 4 (c) one go up pipe and two and manage conductings down, form first state.Fig. 4 (d) to Fig. 4 (f) two go up pipe and one and manage conductings down, form second state.Three pipe conductings down form the third state among Fig. 4 (g).Go up the pipe conducting for three among Fig. 4 (h), form four condition.

By that analogy, (N+1) structural similarity of the structure of attitude switch and four attitude switches, the number of windings of transformer is increased to N, and the brachium pontis number of switching tube also is increased to N simultaneously.Being of wide application of polymorphic switch, both can be used in the single phase circuit also can be used in the three-phase circuit, both can be used in the rectifier also can be used in the inverter, can be used in the structure of boosting also can be used in the buck configuration, can be in the full-bridge topology usefulness, also can in half-bridge topology, use.The present invention then utilizes the above-mentioned characteristic of polymorphic switch to constitute ternary three-level PFC circuit and polymorphic three-level PFC circuit.

See also Fig. 5, be the circuit theory diagrams of ternary three-level PFC circuit first preferred embodiment of the present invention.As shown in Figure 5, the present invention at first provides a kind of ternary three-level PFC circuit, and this pfc circuit comprisesinductance L 1, compound tri-state switch,first capacitor C 1 and second capacitor C 2.Inductance L 1 is connected between AC power AC first end and compound tri-state switchfirst end 201, compound tri-state switchsecond end 202 is connected first end offirst capacitor C 1, compound tri-state switch the3rd end 203 is connected second end ofsecond capacitor C 2, compound tri-state switch the4th end 204 ground connection, second end of first end offirst capacitor C 1,first capacitor C 1 and second end ofsecond capacitor C 2 are exported three level bus level and are come supply load R1.

The compound tri-state switch that adopts among the present invention comprises first tri-state switch and second tri-state switch, and wherein first tri-state switch is worked when ac supply signal is in positive half period, and second tri-state switch is worked when ac supply signal is in negative half-cycle.

As shown in Figure 5, first tri-state switch comprises transformer T, the first diode D1 and D3, switching tube S1 and S2.Wherein the first diode D1 and switching tube S1 constitute first group of brachium pontis.The first diode D3 and switching tube S2 constitute second group of brachium pontis.The end of the same name on the former limit of transformer T and the different name end of secondary link to each other asfirst end 201 of compound tri-state switch.The anode of diode D1 links to each other with the end of the same name of the secondary of transformer T, and negative electrode is that first capacitor C, 1 first end links to each other with compound tri-state switch second end 202.Switching tube S1 is connected across between the end of the same name and ground of secondary of transformer.The anode of diode D3 links to each other with the different name end on the former limit of transformer T, and negative electrode is that first capacitor C, 1 first end links to each other with compound tri-state switch second end 202.Switching tube S2 is connected across between the different name end and ground on former limit of transformer.

Compound tri-state switch also comprises two second diode D2 and D4.The negative electrode of diode D2 is connected to the end of the same name of the secondary of transformer T, and anode is that second capacitor C, 2 second ends link to each other with compound tri-state switch the 3rd end 203.The negative electrode of diode D4 is connected to the different name end on the former limit of transformer T, and anode is that second capacitor C, 2 second ends link to each other with compound tri-state switch the 3rd end 203.Transformer T, two switching tube S1 and S2 and diode D2 and D4 have just constituted second tri-state switch.Turn-on and turn-off by PWM modulates the control switch pipe just can realize the output of different modalities.

See also Fig. 6, be the circuit theory diagrams of ternary three-level PFC circuit second preferred embodiment of the present invention.Above-mentioned switching tube S1 and S2 are the anti-series Mosfet that electric current can two-way flow, and its structure and first embodiment are similar, and difference only is to adopt switching tube Q1 and Q2 anti-series to finish the function of switch S 1.Concrete structure is as follows: the drain electrode of switching tube Q1 links to each other with the end of the same name of the secondary of transformer T, and the source electrode of switching tube Q1 links to each other with the source electrode of switching tube Q2, and the drain electrode of switching tube Q2 links to each other with ground.The drain electrode of switching tube Q3 links to each other with the different name end on the former limit of transformer T, and the source electrode of switching tube Q3 links to each other with the source electrode of switching tube Q4, and the drain electrode of switching tube Q4 links to each other with ground.Just can control the conducting state of brachium pontis by control switching tube Q1, Q2, Q3 and Q4.

See also Fig. 7 (a), Fig. 7 (b) and Fig. 7 (c), 7 (d), be respectively the working mode figure of ternary three-level PFC circuit in the preferred embodiment of the present invention.Mode of operation when wherein Fig. 7 (a) is in positive half period for circuit of the present invention.In this mode of operation, first tri-state switch conducting work.Staggered 180 degree switches of switching tube S1 and S2 wherein, when input voltage AC is in sinusoidal wave positive half period, inductive current will flow through diode D1, diode D3 or switching tube S1, switching tube S2.When the switching tube conducting, then electric current flows through switching tube S1 and switching tube S2, the diode D1 of corresponding brachium pontis and diode D3 otherwise electric current is flowed through.Mode of operation when Fig. 7 (b) is in negative half-cycle for circuit of the present invention.In this mode of operation, second tri-state switch conducting work.When input voltage AC is in sinusoidal wave negative half-cycle, inductive current will flow through diode D2, diode D4 or switching tube S1, switching tube S2.When the switching tube conducting then electric current flow through switching tube S1 and switching tube S2, the diode D2 of corresponding brachium pontis and diode D4 otherwise electric current is flowed through.The third mode of operation when Fig. 7 (c), 7 (d) turn-off for switching tube S1 and S2, first tri-state switch and second tri-state switch respectively have a diode current flow.

The present invention also adopts polymorphic switch to realize polymorphic three-level PFC circuit.This polymorphic three-level PFC circuit comprises: inductance, compound polymorphic switch, first electric capacity and second electric capacity.Inductance is connected between AC power first end and compound polymorphic switch first end, compound polymorphic switch second end is connected first end of second electric capacity, compound polymorphic switch the 3rd end is connected second electric capacity, second end, compound polymorphic switch the 4th end ground connection, second end of first end of first electric capacity, second end of first electric capacity and second electric capacity is exported three level voltages.

In some preferred embodiments of polymorphic three-level PFC circuit provided by the invention, compound polymorphic switch comprises: the second polymorphic switch of working when first polymorphic switch of working when the AC power input signal is in positive half period and AC power input signal are in negative half-cycle.

The first polymorphic switch comprises the transformer with N winding, and wherein N is the integer greater than 2.A secondary N winding of transformer is linked to be equilateral polygon, and the end of the same name of a former limit N winding of transformer links to each other as compound polymorphic switch first end, and the electric current between each winding of former limit equates.The first polymorphic switch comprises also that respectively the N that links to each other with the different name end of the former limit N winding of transformer organizes first diode and switching tube.Wherein the anode of N first diode is connected to the different name end of a former limit N winding of transformer respectively, and the negative electrode of N first diode links to each other with first end of first electric capacity.N switching tube is connected across respectively between the different name end and ground of a former limit N winding of transformer.

Compound polymorphic switch also comprises N second diode.The negative electrode of N second diode is connected to the different name end of a former limit N winding of transformer respectively, and the anode of N second diode links to each other with second end of second electric capacity.Therefore, transformer, a N switching tube and N second diode constitutes the second polymorphic switch.The i.e. first polymorphic switch and second polymorphic switch common transformer and the switching tube.

Above-mentioned first switching tube be can the electric current two-way flow switching devices such as Mosfet, IGBT.As adopt first switching tube and second switch pipe, and the source electrode of first switching tube and the source electrode of second switch pipe are linked to each other, the drain electrode of second switch pipe links to each other with ground.

See also Fig. 8, be four attitude three-level PFC circuit schematic diagrams in the preferred embodiment of the present invention.As shown in Figure 8, the structure of four attitude three-level PFC circuits and ternary three-level PFC circuit structural similarity, difference is, has used compound four attitude switches.Compound four attitude switches comprise the one or four attitude switch and the two or four attitude switch equally.The conducting work when the AC power input signal is in positive half period of the one or four attitude switch, it mainly comprises transformer T, the first diode D1, D3 and D5, and switching tube S1, S2 and S3.Wherein the first diode D1 and switching tube S1 constitute first group of brachium pontis.The first diode D3 and switching tube S2 constitute second group of brachium pontis.The first diode D5 and switching tube S3 constitute the 3rd group of brachium pontis.The anode of the first diode D1, D3 and D5 is connected respectively to the different name end of 3 windings on the former limit of transformer T, and negative electrode links to each other with compound four attitude switches, second end 202.Switching tube S1, S2 and S3 are connected across respectively between the different name end and ground of 3 windings on former limit of transformer T.By Fig. 4 (a) to the analysis of Fig. 4 (h) as can be known, the one or four attitude switch can be realized the output of four attitudes, three level.Compound four attitude switches also comprise two second diode D2, D4 and D6.The negative electrode of the second diode D2, D4 and D6 is connected respectively to the different name end of 3 windings on the former limit of transformer T, and anode links to each other with compound four attitude switches the 3rd end 203.Transformer T, three switching tube S1, S2 and S3, and diode D2, D4 and D6 have just constituted the two or four attitude switch.Just can corresponding four mode that draw pfc circuit according to the state variation of above-mentioned four attitude switches, thus realize the output of four attitudes, three level.

Below traditional three-level PFC circuit shown in Figure 1 and ternary three-level PFC circuit shown in Figure 6 are carried out emulation.The bearing power that keeps two circuit, input and output voltage and the big small frequency of input current ripple be identical to carry out parameter designing and emulation.

See also the output voltage waveform that Fig. 9 (a) and Fig. 9 (b) are respectively traditional circuit and circuit of the present invention, Figure 10 (a) and Figure 10 (b) are respectively the input current waveform figure of traditional circuit and circuit of the present invention.The output voltage that this shows traditional three-level PFC and ternary three-level PFC is identical, and when load was identical, the input current of ternary three-level PFC circuit provided by the invention was less than the input current of traditional three-level PFC, and visible circuit efficiency provided by the invention is higher.

See also the drive signal waveform figure that Figure 11 (a) and Figure 11 (b) are respectively traditional circuit and circuit of the present invention, Figure 12 (a) and Figure 12 (b) are respectively traditional circuit and circuit inductance current ripples figure of the present invention.Traditional as seen from the figure three-level PFC and ternary three-level PFC have the inductive current ripple of same frequency, and the switching frequency of ternary three-level PFC switching tube only is traditional three-level PFC half, and this also is that ternary three-level PFC has one of more high efficiency reason.

See also Figure 13 (a) and Figure 13 (b) and be respectively traditional circuit and circuit inductance voltage oscillogram of the present invention, Figure 14 (a) and Figure 14 (b) are respectively traditional circuit and circuit inductance current waveform figure of the present invention.The inductance of ternary three-level PFC is withstand voltage to be half of traditional three-level PFC, like this under the identical situation of other conditions, its inductance value can be half of traditional three-level PFC, the inductance volume also reduces, simultaneously, the inductive current ripple of ternary three-level PFC has more ripples in the same cycle be zero point, and this also is of value to the PF value that improves circuit and reduces THD.

See also Figure 15 (a) and be respectively the inductive current ripple figure of the ternary three-level PFC circuit of the present invention when the different duty to Figure 15 (c).Wherein duty ratio is greater than 0.5 among Figure 15 (a), and duty ratio is less than 0.5 among Figure 15 (b), and duty ratio equals 0.5 among Figure 15 (c).As seen the inductive current ripple frequency is the twice of switching frequency, and the inductance ripple current is 0.5 o'clock to be zero in duty ratio.

See also Figure 16 (a) and Figure 16 (b) and be respectively traditional circuit and circuit of the present invention voltage oscillogram at switching tube group two ends.To be Figure 16 (a) be Fig. 1mid point 101 and the voltage oscillogram of putting between 102, Figure 16 (b) is the voltage oscillogram between transformer rear end and the ground among Fig. 6.Figure 16 (c) is the voltage oscillogram of transformer T front end in the circuit diagram 6 of thepresent invention 201 with ground.The transformer front end of ternary three-level PFC circuit then presents five level to the voltage on ground, and this also is of value to the PF value that improves circuit and reduces THD.

If keep identical inductive current ripple size and frequency as can be seen from comparative result, the switching frequency of the ternary three-level PFC of the present invention is half of common three level, thereby makes the switching frequency of polymorphic three-level PFC reduce, and corresponding efficient improves.Since this moment polymorphic three-level PFC also corresponding the reducing of inductance value, the big or small sum of inductance and transformer does not increase, and is basic identical with the inductance size of traditional three-level PFC.

In addition, if only keep the inductive current ripple of identical size, adopt identical switching frequency, then the inductive current ripple frequency of polymorphic three-level PFC can be multiplied, and this moment, the volume of inductance and transformer can significantly reduce.The inductance value of single-phase ternary three-level PFC is that the inductance value of 1/4, four attitude three-level PFC of traditional three-level PFC is 1/9 of traditional three-level PFC, and its THD is also less than traditional circuit.If be applied to three-phase circuit, inductance reduces can be more.

Common inductor design process is as follows:

If inductance value is L, the maximum current that flows through inductance is Io, and the window utilance of magnetic core is Kw, and current in wire density is Jc, and peakflux density is Bmax, and the needed product of areas of inductance is AP.

Then the design principle according to inductance can draw:

$\mathrm{AP}=\frac{L*{\mathrm{<figure-callout\; label="Io"\; filenames="HSA00000074279600021.png,HSA00000074279600022.png"\; state="\{\{state\}\}">Io</figure-callout>}}^2}{\mathrm{Kw}*B\max *\mathrm{Jc}}$

Order$K=\frac{{\mathrm{<figure-callout\; label="Io"\; filenames="HSA00000074279600021.png,HSA00000074279600022.png"\; state="\{\{state\}\}">Io</figure-callout>}}^2}{\mathrm{Kw}*B\max *\mathrm{Jc}}$

Can draw

AP＝K*L

AP is the product of magnetic core window area and magnetic core sectional area, if select identical K for use, then the size of inductance volume becomes certain proportional relationship with inductance value, and why Here it is can obviously reduce the reason of inductor size with polymorphic three-level PFC.

This shows that polymorphic three-level PFC circuit provided by the invention can improve circuit characteristic, and design the size that significantly improves efficient or significantly reduce passive device as required.

In sum, the present invention proposes a kind of ternary three-level PFC circuit and the polymorphic three-level PFC circuit structure that can improve circuit characteristic, and the advantage of using this structure is as follows:

1) polymorphic three-level PFC converter does not need special flow equalizing circuit, because the secondary of transformer can natural current-sharing;

2) stress of reduction passive device such as electric capacity (dc-link capacitance, filter capacitor) and inductance (filter inductance, buck inductance);

3) reduce the conducting and the switching loss (can use the P cock pipe under the equal-wattage grade) of switching tube;

4) improve system dynamic characteristic;

5) improve systematic function, improve power factor, reduce total harmonic distortion;

6) design the size that can significantly improve efficient or reduce passive device as required.

The present invention is described according to specific embodiment, but it will be understood by those skilled in the art that when not breaking away from the scope of the invention, can carry out various variations and be equal to replacement.In addition, for adapting to the specific occasion or the material of the technology of the present invention, can carry out many modifications and not break away from its protection range the present invention.Therefore, the present invention is not limited to specific embodiment disclosed herein, and comprises that all drop into the embodiment of claim protection range.

Claims (8)

1. a ternary three-level PFC circuit is characterized in that, described ternary three-level PFC circuit comprises: inductance, compound tri-state switch, first electric capacity and second electric capacity;

Described inductance is connected between AC power first end and compound tri-state switch first end, compound tri-state switch second end is connected first end of first electric capacity, compound tri-state switch the 3rd end is connected second end of second electric capacity, compound tri-state switch the 4th end ground connection, second end of first end of first electric capacity, second end of first electric capacity and second electric capacity is exported three level voltages.

2. ternary three-level PFC circuit according to claim 1 is characterized in that, described compound tri-state switch comprises:

Second tri-state switch of working when first tri-state switch of working when the AC power input signal is in positive half period and AC power input signal are in negative half-cycle.

3. ternary three-level PFC circuit according to claim 2 is characterized in that, described first tri-state switch comprises:

Transformer, the end of the same name on the former limit of described transformer and the different name end of secondary link to each other as first end of compound tri-state switch;

Two first diodes and two switching tubes; The anode of two first diodes is connected to the different name end on former limit of transformer and the end of the same name of secondary respectively, and the negative electrode of two first diodes all links to each other with first end of first electric capacity; First switching tube is connected across between the different name end and ground on former limit of transformer, and second switching tube is connected across between the end of the same name and ground of secondary of transformer.

4. ternary three-level PFC circuit according to claim 3 is characterized in that, described compound tri-state switch also comprises: two second diodes; The negative electrode of two second diodes is connected to the different name end on former limit of transformer and the end of the same name of secondary respectively, the anode of two second diodes all links to each other with second end of second electric capacity, and described transformer, two switching tubes and described two second diodes constitute second tri-state switch.

5. a polymorphic three-level PFC circuit is characterized in that, described polymorphic three-level PFC circuit comprises: inductance, compound polymorphic switch, first electric capacity and second electric capacity;

Described inductance is connected between AC power first end and compound polymorphic switch first end, compound polymorphic switch second end is connected first end of first electric capacity, compound polymorphic switch the 3rd end connects second end of second electric capacity, compound polymorphic switch the 4th end ground connection, second end of first end of first electric capacity, second end of first electric capacity and second electric capacity is exported three level voltages.

6. polymorphic three-level PFC circuit according to claim 5 is characterized in that, described compound polymorphic switch comprises:

The second polymorphic switch of working when first polymorphic switch of working when the AC power input signal is in positive half period and AC power input signal are in negative half-cycle.

7. polymorphic three-level PFC circuit according to claim 6 is characterized in that, the described first polymorphic switch comprises:

Transformer with N winding, wherein N is the integer greater than 2; A secondary N winding of described transformer is linked to be equilateral polygon, and the end of the same name of a former limit N winding of described transformer links to each other as compound polymorphic switch first end;

The N that links to each other with the different name end of the former limit N winding of transformer organizes first diode and switching tube respectively, wherein the anode of N first diode is connected to the different name end of a former limit N winding of transformer respectively, and the negative electrode of N first diode links to each other with first end of first electric capacity; N switching tube is connected across respectively between the different name end and ground of a former limit N winding of transformer.

8. polymorphic three-level PFC circuit according to claim 7 is characterized in that, described compound polymorphic switch also comprises: N second diode; The negative electrode of described N second diode is connected to the different name end of a former limit N winding of transformer respectively, and the anode of N second diode links to each other with second end of second electric capacity; Described transformer, a described N switching tube and described N second diode constitutes the second polymorphic switch.

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