CN103840684B - High-power offset-type cascade diode H bridge unit power factor rectifier - Google Patents
High-power offset-type cascade diode H bridge unit power factor rectifier Download PDFInfo
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- CN103840684B CN103840684B CN201410090383.6A CN201410090383A CN103840684B CN 103840684 B CN103840684 B CN 103840684B CN 201410090383 A CN201410090383 A CN 201410090383A CN 103840684 B CN103840684 B CN 103840684B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The present invention high-power offset-type cascade diode H bridge unit power factor rectifier, including being connect by several modular units three-phase star of forming of cascade, the multiple main power circuit that connects of corner connection or double star, provide serial or parallel connection or the series and parallel device of relatively low capacity simultaneously, unit power factor rectifier can be easily carried out.Have an advantage in that: the power rectifier conversion that low pressure power switch pipe can be used to complete under high voltage, without using power frequency phase-shifting transformer huge, heavy, that wiring is complicated, simplify the topological structure of main power circuit, greatly reduce the use of switching device, and then decrease the loss in circuit work, and improve the work efficiency of system, volume is little, lightweight, low cost.Make commutator simultaneously in the case of load change, remain that power factor is 1.In applications such as HVDC Transmission, high-power electric and electronic transformator, high-power mesohigh ac-dc-ac frequency converters, there is important using value.
Description
Technical field
The present invention relates to commutator, particularly to high-power offset-type cascade diode H bridge unit power factor rectifier.
Background technology
Along with science and technology and the fast development of the modernization of industry and the requirement to the saving energy, it is applied to large-power occasions
Mesohigh electronic power convertor plays the most important effect.In recent years, many level power current transformer (Multilevel
Converter) in high-tension high-power frequency control, active electric filter device, HVDC (HVDC) transmission of electricity it is
The application succeeded in the fields such as system and power system reactive power compensation.The basic circuit topological structure master of Multilevel Inverters
Diode clamp formula to be had, flying capacitor type and 3 kinds of circuit of cascade of power units formula.Wherein, cascade of power units
Formula Multilevel Inverters is because of advantages such as its modularized design, reliability height, little, the input-output power wide ranges of harmonic pollution
And become the market mainstream.But, the major defect that traditional cascade of power units formula many level power current transformer exists be
Power input needs the Industrial Frequency Transformer applying bulky wiring complicated, and this makes it be subject in the application of many industrial occasions
Arrive restriction.Thus, cancel the Industrial Frequency Transformer in traditional power cell Cascaded multi-level converter circuit, design
The Cascaded multi-level converter circuit of no industrial frequency transformer, it will bring revolutionary change to this type of Multilevel Inverters
Leather.Research in this direction is the focus that power electronics and power drives area research personnel pay close attention to the most always,
It it is one of current important subject of electric and electronic technical field.
Publicity patent of invention " high power cascade type diode H-bridge unit power factor rectifier "
(CN201310177775.1, CN103269171A) proposes a kind of by single-phase H bridge diode rectifier+Boost
Circuit constitutes the scheme of high-power cascade rectifier as elementary cell cascade, the control calculation that the application of this scheme is certain
Method can make each module output voltage keep balance when loading unequal, and input current waveform is close to sine, input electricity
Flow and keep consistent with input voltage phase, it is achieved unit power factor rectifier.But owing to the input inductance of the program is positioned at
After diode rectification, in switching process under certain operating mode the electric current in certain or certain multiple inductance can through switching tube and
Corresponding diode rectifier bridge forms circulation, and making these diode rectifier bridge AC voltages is zero, thus causes cascade its
In his module, diode rectifier bridge bears whole supply voltages, and this just loses by cascade diode reduction diode resistance to
The meaning of pressure value.
Summary of the invention
It is an object of the invention to overcome drawbacks described above, it is provided that the first high-power offset-type cascade diode H bridge unit power
Factory rectifier, inductance is put into the input of diode rectifier bridge, thus has been inherently eliminated inductance by this current transformer
In electric current form the possibility of circulation through switching tube and corresponding diode rectifier bridge, by suitable control method, make level
Join each module output voltage and reach equilibrium, make input current close to sinusoidal wave form, and by rectifier input increase relatively
The series compensation of low capacity, or shunt compensation, or series and parallel, make input voltage and input current keep same phase,
Realize unit power factor rectifier.This current transformer is without using power frequency phase-shifting transformer, and work efficiency is high, and volume is little,
Lightweight, low cost, use low pressure power switch pipe to complete the power rectifier under high voltage by the way of cascade
Conversion.
For reaching above-mentioned purpose, the one high-power offset-type cascade diode H bridge unity power factor that the present invention provides is whole
Stream device, including main power circuit, described main power circuit includes inputting inductance, single-phase diode rectifier bridge and N number of first
Modular unit, wherein N is positive integer, and described first modular unit includes that switching device, fast recovery diode, output are straight
Stream electric capacity and load, the second terminals of the switching device in N number of described first modular unit and the next institute cascaded
The first terminals stating the switching device in the first modular unit are sequentially connected, remaining after described first modular unit cascade
Two free ends, the first terminals of the switching device in i.e. first the first modular unit and single-phase diode rectifier bridge
Direct current positive output end is connected, the second terminals of the switching device in n-th the first modular unit and single-phase diode rectification
The direct current negative output terminal of bridge is connected, and constitutes the second modular unit, and described main power circuit also includes single-phase series compensating module
Unit, described single-phase series compensating module unit includes Monophase electric power electronic inverter, LC wave filter and transformator, its
In, LC filters in series is connected between the secondary side of transformator and Monophase electric power electronic inverter, the one of described transformator
Connect with input inductance and the second modular unit and access AC network in secondary side.
A kind of high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said single-phase series
Compensating module unit replaces with parallel single-phase compensating module unit, and described parallel single-phase compensating module unit includes that another is single-phase
Electronic power convertor, another filter inductance and another transformator, wherein, another filter inductance series connection is in another transformation
Between secondary side and the Monophase electric power electronic inverter of device, the primary side of another transformator described is in parallel with AC network even
Connect.
A kind of high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said main power electricity
Road also includes that parallel single-phase compensating module unit and electric capacity, described parallel single-phase compensating module unit include another Monophase electric power
Electronic inverter, another filter inductance and another transformator, wherein, another filter inductance series connection is at another transformator
Between secondary side and Monophase electric power electronic inverter, described electric capacity is connected in parallel to described Monophase electric power electronic inverter with described
Between another Monophase electric power electronic inverter, the primary side of another transformator described is connected in parallel with AC network.
For reaching above-mentioned purpose, the another kind high-power offset-type cascade diode H bridge unity power factor that the present invention provides
Commutator, including main power circuit, described main power circuit include input inductance, single-phase diode rectifier bridge and several
First modular unit, wherein N is positive integer, and described first modular unit includes switching device, fast recovery diode, defeated
Go out DC capacitor and load, the second terminals of the switching device in N number of described first modular unit and next cascaded
First terminals of the switching device in individual described first modular unit are sequentially connected, institute after described first modular unit cascade
Remain two free ends, the first terminals of the switching device in i.e. first the first modular unit and single-phase diode rectification
The direct current positive output end of bridge is connected, the second terminals of the switching device in n-th the first modular unit and single-phase diode
The direct current negative output terminal of rectifier bridge is connected, and constitutes described second modular unit；Each institute in M described second modular unit
Another of ac input end single-phase diode described with next one rectifier bridge stating single-phase diode rectifier bridge exchanges
Input is sequentially connected, and remains two free ends, i.e. first single-phase diode rectification after described second modular unit cascade
Another ac input end of bridge and an ac input end of m-th single-phase diode rectifier bridge, described the second of cascade
Modular unit constitutes three module unit, and wherein M is positive integer, and described main power circuit also includes that single-phase series compensates mould
Module unit, described single-phase series compensating module unit includes Monophase electric power electronic inverter, LC wave filter and transformator,
Wherein, LC filters in series is connected between the secondary side of transformator and Monophase electric power electronic inverter, described transformator
Primary side is connected with input inductance and three module unit and is accessed AC network.
The another kind of high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said single-phase string
Connection compensating module unit replaces with parallel single-phase compensating module unit, and described parallel single-phase compensating module unit includes that another is single
Phase electronic power convertor, another filter inductance and another transformator, wherein, another filter inductance series connection becomes at another
Between secondary side and the Monophase electric power electronic inverter of depressor, the primary side of another transformator described is in parallel with AC network even
Connect.
The another kind of high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said main power
Circuit also includes that parallel single-phase compensating module unit and electric capacity, described parallel single-phase compensating module unit include another single-phase electricity
Power electronic inverter, another filter inductance and another transformator, wherein, another filter inductance series connection is at another transformator
Secondary side and Monophase electric power electronic inverter between, described electric capacity is connected in parallel to described Monophase electric power electronic inverter and institute
Stating between another Monophase electric power electronic inverter, the primary side of another transformator described is connected in parallel with AC network.
For reaching above-mentioned purpose, the present invention provide the third high-power offset-type cascade diode H bridge unit power because of
Number commutators, including three-phase main power circuit, described three-phase main power circuit include 3 input inductance and by several the
3 three module unit that one modular unit respectively constitutes, 3 input inductance and 3 three module unit constitute star
Connecting, wherein, described first modular unit includes switching device, fast recovery diode, output DC capacitor and load,
Second terminals of the switching device in each described first modular unit and described first modular unit of the next one cascaded
In the first terminals of switching device be sequentially connected, remaining two free ends after described first modular unit cascade, i.e.
First terminals of the switching device in first the first modular unit and the direct current positive output end of single-phase diode rectifier bridge
Being connected, the second terminals of the switching device in n-th the first modular unit are born with the direct current of single-phase diode rectifier bridge
Outfan is connected, and constitutes described second modular unit；Each described single-phase diode in M described second modular unit
Another ac input end phase successively of one ac input end single-phase diode described with next one rectifier bridge of rectifier bridge
Even, another friendship of two free ends, i.e. first single-phase diode rectifier bridge is remained after described second modular unit cascade
Stream input and an ac input end of m-th single-phase diode rectifier bridge, the described second modular unit structure of cascade
Becoming three module unit, wherein M is positive integer；Described three-phase main power circuit also includes three-phase series compensating module list
Unit, described three-phase series compensating module unit includes three-phase power electronic inverter, 3 LC wave filter and 3 transformations
Device, wherein, the respectively series connection of each LC wave filter between the secondary side and three-phase power electronic inverter of each transformator,
The primary side of each described transformator is connected in each phase accessing three-phase alternating current net with 1 input inductance respectively.
The third high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said 3 defeated
Enter inductance and 3 three module unit are replaced and constituted Angle connection.
The third high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said three-phase
Main power circuit is replaced and is included 3 inputs inductance, 6 brachium pontis inductance, 6 three module unit and DC capacitors, institute
State 3 input inductance, 6 brachium pontis inductance, 6 three module unit and DC capacitor and constitute double star connection.
The third high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said three-phase
Series compensation modular unit replaces with parallel three phase compensating module unit, and described parallel three phase compensating module unit includes another
Three-phase power electronic inverter, 3 filter inductances and other 3 transformators, wherein, the series connection respectively of each filter inductance
Between the secondary side and three-phase power electronic inverter of each transformator, of each described other transformator primary side is same
Name end is connected with each other, another Same Name of Ends of each described other transformator primary side respectively with each phase of three-phase alternating current electrical network
It is connected with each other.
The third high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said three-phase string
Connection compensating module unit replace with parallel three phase compensating module unit, described parallel three phase compensating module unit include another three
Phase electronic power convertor, 3 filter inductances and other 3 transformators, wherein, the series connection respectively of each filter inductance is often
Between secondary side and the three-phase power electronic inverter of individual transformator, a Same Name of Ends of each described other transformator primary side
It is connected with each other, another Same Name of Ends of each described other transformator primary side each mutually mutual with three-phase alternating current electrical network respectively
Connect.
The third high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said three-phase
Series compensation modular unit replaces with parallel three phase compensating module unit, and described parallel three phase compensating module unit includes another
Three-phase power electronic inverter, 3 filter inductances and other 3 transformators, wherein, the series connection respectively of each filter inductance
Between the secondary side and three-phase power electronic inverter of each transformator, of each described other transformator primary side is same
Name end is connected with each other, another Same Name of Ends of each described other transformator primary side respectively with each phase of three-phase alternating current electrical network
It is connected with each other.
The third high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said three-phase
Main power circuit also includes that parallel three phase compensating module unit and electric capacity, described parallel three phase compensating module unit include another
Three-phase power electronic inverter, 3 filter inductances and other 3 transformators, wherein, the series connection respectively of each filter inductance
Between the secondary side and three-phase power electronic inverter of each transformator, of each described other transformator primary side is same
Name end is connected with each other, another Same Name of Ends of each described other transformator primary side respectively with each phase of three-phase alternating current electrical network
Being connected with each other, described electric capacity is connected in parallel to described three-phase power electronic inverter and another three-phase power electronic inverter described
Between.
The third high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said three-phase
Main power circuit also includes that parallel three phase compensating module unit and electric capacity, described parallel three phase compensating module unit include another
Three-phase power electronic inverter, 3 filter inductances and other 3 transformators, wherein, the series connection respectively of each filter inductance
Between the secondary side and three-phase power electronic inverter of each transformator, of each described other transformator primary side is same
Name end is connected with each other, another Same Name of Ends of each described other transformator primary side respectively with each phase of three-phase alternating current electrical network
Being connected with each other, described electric capacity is connected in parallel to described three-phase power electronic inverter and another three-phase power electronic inverter described
Between.
The third high-power offset-type cascade diode H bridge unit power factor rectifier of the present invention, wherein said three-phase
Main power circuit also includes that parallel three phase compensating module unit and electric capacity, described parallel three phase compensating module unit include another
Three-phase power electronic inverter, 3 filter inductances and other 3 transformators, wherein, the series connection respectively of each filter inductance
Between the secondary side and three-phase power electronic inverter of each transformator, of each described other transformator primary side is same
Name end is connected with each other, another Same Name of Ends of each described other transformator primary side respectively with each phase of three-phase alternating current electrical network
Being connected with each other, described electric capacity is connected in parallel to described three-phase power electronic inverter and another three-phase power electronic inverter described
Between.
The advantage of the present invention high-power offset-type cascade diode H bridge unit power factor rectifier and having the active effect that
Owing to have employed several modular units cascade composition, therefore low pressure power switch pipe can be used to complete under high voltage
Power rectifier converts, and need not to use huge, heavy, the power frequency phase-shifting transformer that wiring is complicated, simplifies main merit
The topological structure of rate circuit, greatly reduces the use of active switching devices, and then decreases the loss in circuit work,
Improve the work efficiency of system, and by using the series and parallel unit of relatively low capacity, solve this kind of commutator
The problem that power factor reduces with load down.This kind of commutator volume is little, lightweight, low cost, and power factor is high,
Harmonic wave is little.This current transformer is at HVDC Transmission, high-power electric and electronic transformator, high-power mesohigh AC-DC-AC
The applications such as converter have important using value.
It is described in detail referring to the drawings below in conjunction with embodiment.
Accompanying drawing explanation
Fig. 1 is the first modular unit in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit diagram；
Fig. 2 is that in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier, single-phase series compensates
The circuit diagram of unit；
Fig. 3 is that in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier, parallel single-phase compensates
The circuit diagram of unit；
Fig. 4 is first embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Fig. 5 is the second embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Fig. 6 is the 3rd embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Fig. 7 is the second modular unit in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit diagram；
Fig. 8 is the 4th embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Fig. 9 is the 5th embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Figure 10 is sixth embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Figure 11 is the electricity of three module unit in high power cascade type diode H-bridge unit power factor rectifier of the present invention
Lu Tu；
Figure 12 is that in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier, three-phase series compensates
The circuit diagram of unit；
Figure 13 is that in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier, parallel three phase compensates
The circuit diagram of unit；
Figure 14 is the 7th embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Figure 15 is the 8th embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Figure 16 is that in offset-type cascade diode H bridge unit power factor rectifier of the present invention, the circuit of the 9th embodiment is opened up
Flutter structure chart；
Figure 17 is that in offset-type cascade diode H bridge unit power factor rectifier of the present invention, the circuit of the tenth embodiment is opened up
Flutter structure chart；
Figure 18 is the 11st embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Figure 19 is the 12nd embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Figure 20 is the 13rd embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Figure 21 is the 14th embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure；
Figure 22 is the 15th embodiment in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
Circuit topological structure figure.
Detailed description of the invention
Voltage rating in view of diode can not be the highest, when for higher voltage occasion, just remains a need for using
The mode of diode rectifier bridge cascade.To this end, the present invention high-power offset-type cascade diode H bridge unit power because of
In the embodiment of number commutator, cascade diode H bridge unit power factor rectifier is to be cascaded by several modular units
And the circuit topology formed a whole.
With reference to Fig. 1, Fig. 2 and Fig. 4, in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
First embodiment in, main power circuit includes that single-phase series compensating module unit, input inductance L, single-phase diode are whole
Stream bridge and N number of first modular unit A, wherein N is positive integer.
First modular unit A includes switching device, fast recovery diode, output DC capacitor and load.N number of first mould
Second terminals d of the switching device in module unit A and the switching device in the next one the first modular unit A cascaded
The first terminals c be sequentially connected, first modular unit A cascade after remaining two free ends, i.e. first the first mould
First terminals c of the switching device in module unit A is connected with the direct current positive output end of single-phase diode rectifier bridge, N
Second terminals d of the switching device in individual first modular unit A and the direct current negative output terminal phase of single-phase diode rectifier bridge
Even, the second modular unit B is constituted.
Single-phase series compensating module unit includes Monophase electric power electronic inverter, LC wave filter L1C1 and transformator T1.Its
In, LC wave filter L1C1 series connection between the secondary side and Monophase electric power electronic inverter of transformator T1, transformator T1
Primary side with input inductance L and the second modular unit B connect access AC network.
With reference to Fig. 1, Fig. 3 and Fig. 5, in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
The second embodiment in, the single-phase series compensating module unit in embodiment one replaces with parallel single-phase compensating module unit.
Parallel single-phase compensating module unit includes another Monophase electric power electronic inverter, another filter inductance L2 and another transformator
T2, wherein, the L2 series connection of another filter inductance another transformator T2 secondary side and Monophase electric power electronic inverter it
Between, the primary side of another transformator T2 is connected in parallel with AC network.
With reference to Fig. 1, Fig. 2, Fig. 3 and Fig. 6, whole at the present invention high-power offset-type cascade diode H bridge unity power factor
In 3rd embodiment of stream device, the main power circuit in embodiment one also includes parallel single-phase compensating module unit and electric capacity
C2.Electric capacity C2 is connected in parallel between Monophase electric power electronic inverter and another Monophase electric power electronic inverter.Parallel single-phase
The primary side of another transformator T2 in compensating module unit is connected in parallel with AC network.
With reference to Fig. 2, Fig. 7 and Fig. 8, in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
The 4th embodiment in, main power circuit includes that single-phase series compensating module unit, input inductance L, single-phase diode are whole
Stream bridge and several first modular units A, wherein N is positive integer.
N number of first modular unit A cascade constitutes described second modular unit B.Each single-phase in M the second modular unit B
One ac input end b of diode rectifier bridge depends on another ac input end a of next single-phase diode rectifier bridge
Secondary connected, the second modular unit B remains another of two free ends, i.e. first single-phase diode rectifier bridge after cascading
An ac input end a and ac input end b of m-th single-phase diode rectifier bridge, the second modular unit B structure of cascade
Becoming three module unit C, wherein M is positive integer.
The primary side of the transformator T1 in single-phase series compensating module unit is connected with input inductance L and three module unit C
Incoming transport electrical network.
With reference to Fig. 3, Fig. 7 and Fig. 9, in the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
The 5th embodiment in, the single-phase series compensating module unit in embodiment four replaces with parallel single-phase compensating module unit,
The primary side of another transformator T2 in parallel single-phase compensating module unit is connected in parallel with AC network.
With reference to Fig. 2, Fig. 3, Fig. 7 and Figure 10, at the present invention high-power offset-type cascade diode H bridge unity power factor
In the sixth embodiment of commutator, the main power circuit in embodiment four also includes parallel single-phase compensating module unit and electric capacity
C2.Electric capacity C2 is connected in parallel between Monophase electric power electronic inverter and another Monophase electric power electronic inverter.Parallel single-phase
The primary side of another transformator T2 in compensating module unit is connected in parallel with AC network.
With reference to Figure 11, Figure 12 and Figure 14, at the present invention high-power offset-type cascade diode H bridge unity power factor
In 7th embodiment of commutator, including three-phase main power circuit, three-phase main power circuit includes three-phase series compensating module
Unit, 3 input inductance L101-L103 and 3 three modules respectively constituted by several first modular units A
Unit C, 3 input inductance L101-L103 and 3 three module unit C constitute Y-connection.
Wherein, the first modular unit A includes switching device, fast recovery diode, output DC capacitor and load.N number of
Second terminals d of the switching device in the first modular unit A and opening in the next one the first modular unit A cascaded
The the first terminals c closing device is sequentially connected, remaining two free ends after the first modular unit A cascade, i.e. first
First terminals c of the switching device in the first modular unit A and the direct current positive output end phase of single-phase diode rectifier bridge
Even, the second terminals d of the switching device in n-th the first modular unit A bears defeated with the direct current of single-phase diode rectifier bridge
Go out end to be connected, constitute the second modular unit B.
One ac input end b of each single-phase diode rectifier bridge in M the second modular unit B and the next one single-phase two
Another ac input end a of pole pipe rectifier bridge is sequentially connected, and remains two free ends after the second modular unit B cascade,
Another ac input end a of i.e. first single-phase diode rectifier bridge and a friendship of m-th single-phase diode rectifier bridge
Stream input b, the second modular unit B of cascade constitute three module unit C, and wherein M is positive integer.
Three-phase series compensating module unit includes three-phase power electronic inverter, 3 LC wave filter L11C11-L13
C13 and 3 transformator T11-T13.Wherein, each LC wave filter L11C11-L13C13 series connection respectively is often
Between secondary side and the three-phase power electronic inverter of individual transformator T11 or T12 or T13, each described transformator T11
The primary side of-T13 is connected with 1 input inductance L101 or L102 or L103 respectively and is accessed the every of three-phase alternating current net
In one phase.
With reference to Figure 11, Figure 12 and Figure 15, at the present invention high-power offset-type cascade diode H bridge unity power factor
In 8th embodiment of commutator, 3 input inductance L101-L103 in embodiment seven and 3 three module unit
C replaces and constitutes Angle connection.
With reference to Figure 11, Figure 12 and Figure 16, at the present invention high-power offset-type cascade diode H bridge unity power factor
In 9th embodiment of commutator, the three-phase main power circuit in embodiment seven is replaced and is included 3 input inductance L101-
L103,6 brachium pontis inductance L104-L109,6 three module unit C and DC capacitor C101,3 input electricity
Sense L101-L103,6 brachium pontis inductance L104-L109,6 three module unit C and DC capacitor C101 structure
Double star is become to connect.
With reference to Figure 11, Figure 13 and Figure 17, at the present invention high-power offset-type cascade diode H bridge unity power factor
In tenth embodiment of commutator, the three-phase series compensating module unit in embodiment seven replaces with parallel three phase compensating module
Unit.
Parallel three phase compensating module unit include another three-phase power electronic inverter, 3 filter inductance L21-L23 and
Other 3 transformator T21-T23, wherein, each filter inductance L21-L23 series connection respectively is at each transformator T21
Between secondary side and the three-phase power electronic inverter of-T23, the one of each described other transformator T21-T23 primary side
Individual Same Name of Ends is connected with each other, and another Same Name of Ends of each described other transformator T21-T23 primary side intersects with three respectively
Each phase of stream electrical network is connected with each other.
With reference to Figure 11, Figure 13 and Figure 18, at the present invention high-power offset-type cascade diode H bridge unit power factor rectifier
In 11st embodiment of device, the three-phase series compensating module unit in embodiment eight replaces with parallel three phase compensating module list
Unit.
With reference to Figure 11, Figure 13 and Figure 19, at the present invention high-power offset-type cascade diode H bridge unity power factor
In 12nd embodiment of commutator, the three-phase series compensating module unit in embodiment nine replaces with parallel three phase and compensates mould
Module unit.
With reference to Figure 11, Figure 12, Figure 13 and Figure 20, in the present invention high-power offset-type cascade diode H bridge specific work
In 13rd embodiment of rate factory rectifier, the three-phase main power circuit in embodiment seven also includes that parallel three phase compensates mould
Module unit and electric capacity C30.Electric capacity C30 is connected in parallel to three-phase power electronic inverter and another three-phase power electronics unsteady flow
Between device.
With reference to Figure 11, Figure 12, Figure 13 and Figure 21, in the present invention high-power offset-type cascade diode H bridge specific work
In 14th embodiment of rate factory rectifier, the three-phase main power circuit in embodiment eight also includes that parallel three phase compensates mould
Module unit and electric capacity C30.Electric capacity C30 is connected in parallel to three-phase power electronic inverter and another three-phase power electronics unsteady flow
Between device.
With reference to Figure 11, Figure 12, Figure 13 and Figure 22, in the present invention high-power offset-type cascade diode H bridge specific work
In 15th embodiment of rate factory rectifier, the three-phase main power circuit in embodiment nine also includes that parallel three phase compensates mould
Module unit and electric capacity C30.Electric capacity C30 is connected in parallel to three-phase power electronic inverter and another three-phase power electronics unsteady flow
Between device.
The new diode H-bridge cascade rectifier circuit topology that the present invention proposes and publicity patent of invention " high-power tandem type
Diode H bridge unit power factor rectifier " difference be: inductance is put into diode rectifier bridge by patent of the present invention
Input, the electric current being thus inherently eliminated in inductance forms ring through switching tube and corresponding diode rectifier bridge
The possibility of stream.By suitable control method, make cascade each module output voltage reach equilibrium, make input current connect simultaneously
Nearly sinusoidal wave form.Owing to this circuit substantially makes input voltage and electric current have a phase place changed with load
Difference, also cannot realize unit power factor rectifier.To this end, the present invention is in the series connection of rectifier input increase relatively low capacity
Compensate, or shunt compensation, or series and parallel, thus can be easily carried out unit power factor rectifier, its electricity
Road topological circuit simple in construction, low cost, easily realize, have important in the industrial occasions of energy one direction transmission
Using value and good application prospect.
Embodiment described above is only to be described the preferred embodiment of the present invention, the not design to the present invention
Being defined with scope, without departing under design premise of the present invention, in this area, engineers and technicians are to the present invention's
Various modification that technical scheme is made and improvement, all should fall into protection scope of the present invention, the technology that the present invention is claimed
Content, all records in detail in the claims.
Claims (5)
1. a high-power offset-type cascade diode H bridge unit power factor rectifier, including main power circuit, institute
State main power circuit and include inputting inductance (L), single-phase diode rectifier bridge and N number of first modular unit (A), wherein
N is positive integer, described first modular unit (A) include switching device, fast recovery diode, output DC capacitor and
Load, the second terminals (d) of the switching device in N number of described first modular unit (A) and next cascaded
First terminals (c) of the switching device in individual described first modular unit (A) are sequentially connected, described first module
Remaining two free ends after unit (A) cascade, the of the switching device in i.e. first the first modular unit (A)
One terminals (c) are connected with the direct current positive output end of single-phase diode rectifier bridge, n-th the first modular unit (A)
In the second terminals (d) of switching device be connected with the direct current negative output terminal of single-phase diode rectifier bridge, constitute second
Modular unit (B), it is characterised in that: described main power circuit also includes single-phase series compensating module unit, described list
The compensating module unit that is in series includes Monophase electric power electronic inverter, LC wave filter (L1, C1) and transformator (T1),
Wherein, LC wave filter (L1, C1) series connection transformator (T1) secondary side and Monophase electric power electronic inverter it
Between, the primary side of described transformator (T1) is connected incoming transport with input inductance (L) and the second modular unit (B)
Electrical network；Described main power circuit also includes parallel single-phase compensating module unit and electric capacity (C2), and described parallel single-phase compensates
Modular unit includes another Monophase electric power electronic inverter, another filter inductance (L2) and another transformator (T2), its
In, another filter inductance (L2) series connection becomes with another Monophase electric power electronics at the secondary side of another transformator (T2)
Between stream device, described electric capacity (C2) is connected in parallel to described Monophase electric power electronic inverter and another Monophase electric power electricity described
Between sub-current transformer, the primary side of described another transformator (T2) is connected in parallel with AC network.
2. a high-power offset-type cascade diode H bridge unit power factor rectifier, including main power circuit, institute
State main power circuit and include inputting inductance (L), single-phase diode rectifier bridge and N number of first modular unit (A), wherein
N is positive integer, described first modular unit (A) include switching device, fast recovery diode, output DC capacitor and
Load, the second terminals (d) of the switching device in N number of described first modular unit (A) and next cascaded
First terminals (c) of the switching device in individual described first modular unit (A) are sequentially connected, described first module
Remaining two free ends after unit (A) cascade, the of the switching device in i.e. first the first modular unit (A)
One terminals (c) are connected with the direct current positive output end of single-phase diode rectifier bridge, n-th the first modular unit (A)
In the second terminals (d) of switching device be connected with the direct current negative output terminal of single-phase diode rectifier bridge, constitute second
Modular unit (B)；One exchange of each described single-phase diode rectifier bridge in M described second modular unit (B)
Another ac input end (a) of input (b) single-phase diode described with next one rectifier bridge is sequentially connected, described
Another exchange of two free ends, i.e. first single-phase diode rectifier bridge is remained after second modular unit (B) cascade
Input (a) and an ac input end (b) of m-th single-phase diode rectifier bridge, described second module of cascade
Unit (B) constitutes three module unit (C), and wherein M is positive integer, it is characterised in that: described main power circuit
Also include single-phase series compensating module unit, described single-phase series compensating module unit include Monophase electric power electronic inverter,
LC wave filter (L1, C1) and transformator (T1), wherein, LC wave filter (L1, C1) series connection is at transformator
(T1) between secondary side and Monophase electric power electronic inverter, the primary side of described transformator (T1) and input inductance
(L) connect access AC network with three module unit (C)；Described main power circuit also includes that parallel single-phase compensates
Modular unit and electric capacity (C2), described parallel single-phase compensating module unit includes another Monophase electric power electronic inverter, another
One filter inductance (L2) and another transformator (T2), wherein, another filter inductance (L2) series connection is in another transformation
Between secondary side and another Monophase electric power electronic inverter of device (T2), described electric capacity (C2) is connected in parallel to described list
Between phase electronic power convertor and another Monophase electric power electronic inverter described, the one of described another transformator (T2)
Secondary side is connected in parallel with AC network.
3. a high-power offset-type cascade diode H bridge unit power factor rectifier, including three-phase main power circuit,
Described three-phase main power circuit includes 3 input inductance and respectively constitute by N number of first modular unit (A) 3 the
Three module unit (C), 3 inputs inductance (L101-L103) and 3 three module unit (C) constitute star even
Connecing, wherein, N is positive integer, and described first modular unit (A) includes switching device, fast recovery diode, output
DC capacitor and load, the second terminals (d) of the switching device in each described first modular unit (A) and institute's level
First terminals (c) of the switching device in described first modular unit of the next one (A) of connection are sequentially connected, described
Remaining two free ends after first modular unit (A) cascade, the switch in i.e. first the first modular unit (A)
First terminals of device are connected with the direct current positive output end of single-phase diode rectifier bridge, n-th the first modular unit (A)
In the second terminals of switching device be connected with the direct current negative output terminal of single-phase diode rectifier bridge, constitute the second module list
Unit (B)；One ac input end of each described single-phase diode rectifier bridge in M described second modular unit (B)
B another ac input end (a) of () single-phase diode described with next one rectifier bridge is sequentially connected, described second mould
Another ac input end of two free ends, i.e. first single-phase diode rectifier bridge is remained after module unit (B) cascade
One ac input end (b) of (a) and m-th single-phase diode rectifier bridge, described second modular unit (B) of cascade
Constituting three module unit (C), wherein M is positive integer, it is characterised in that: described three-phase main power circuit also includes
Three-phase series compensating module unit, described three-phase series compensating module unit include three-phase power electronic inverter, 3
LC wave filter (L11C11-L13C13) and 3 transformators (T11-T13), wherein, each LC wave filter (L11
C11-L13C13) series connection is electric with three-phase power at the secondary side of each transformator (T11 or T12 or T13) respectively
Between sub-current transformer, the primary side of each described transformator (T11-T13) inputs inductance (L101 or L102 with 1 respectively
Or L103) series connection access three-phase alternating current net each phase in；Described three-phase main power circuit also includes that parallel three phase is mended
Repay modular unit and electric capacity (C30), described parallel three phase compensating module unit include another three-phase power electronic inverter,
3 filter inductances (L21-L23) and other 3 transformators (T21-T23), wherein, each filter inductance (L21
-L23) respectively series connection is in the secondary side of each other transformator (T21-T23) and another three-phase power electronics unsteady flow
Between device, a Same Name of Ends of each described other transformator (T21-T23) primary side is connected with each other, each described additionally
Another Same Name of Ends of transformator (T21-T23) primary side each phase with three-phase alternating current electrical network respectively is connected with each other,
Described electric capacity (C30) be connected in parallel to described three-phase power electronic inverter and another three-phase power electronic inverter described it
Between.
High-power offset-type cascade diode H bridge unit power factor rectifier the most according to claim 3, its
It is characterised by: wherein said 3 inputs inductance (L101-L103) and 3 three module unit (C) are replaced and constituted
Angle connection；Described three-phase main power circuit also includes parallel three phase compensating module unit and electric capacity (C30), described three
The compensating module unit that is in parallel includes another three-phase power electronic inverter, 3 filter inductances (L21-L23) and additionally
3 transformators (T21-T23), wherein, each filter inductance (L21-L23) series connection respectively is in each other transformation
Between secondary side and another three-phase power electronic inverter of device (T21-T23), each described other transformator (T21
-T23) Same Name of Ends of primary side is connected with each other, another of each described other transformator (T21-T23) primary side
Individual Same Name of Ends each phase with three-phase alternating current electrical network respectively is connected with each other, and described electric capacity (C30) is connected in parallel to described three-phase
Between electronic power convertor and another three-phase power electronic inverter described.
High-power offset-type cascade diode H bridge unit power factor rectifier the most according to claim 3, its
It is characterised by: wherein said three-phase main power circuit is replaced and included 3 inputs inductance (L101-L103), 6 brachium pontis
Inductance (L104-L109), 6 three module unit (C) and DC capacitor (C101), described 3 input inductance
(L101-L103), 6 brachium pontis inductance (L104-L109), 6 three module unit (C) and DC capacitor (C101)
Constitute double star to connect；Described three-phase main power circuit also includes parallel three phase compensating module unit and electric capacity (C30),
Described parallel three phase compensating module unit includes another three-phase power electronic inverter, 3 filter inductances (L21-L23)
With other 3 transformators (T21-T23), wherein, each filter inductance (L21-L23) respectively series connection each separately
Between secondary side and another three-phase power electronic inverter of outer transformator (T21-T23), each described other transformator
(T21-T23) Same Name of Ends of primary side is connected with each other, each described other transformator (T21-T23) primary side
Another Same Name of Ends each phase with three-phase alternating current electrical network respectively be connected with each other, described electric capacity (C30) is connected in parallel to institute
State between three-phase power electronic inverter and another three-phase power electronic inverter described.
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| CN104184350B (en) * | 2014-07-28 | 2017-09-19 | 中国矿业大学(北京) | High-power Mixed cascading bridge-type Unity Power Factor PWM Rectifier Based |
| CN106100317B (en) * | 2016-06-30 | 2019-04-19 | 上海交通大学 | ISIPOSOP type modular DC-DC converter, composition method thereof and output voltage control method |
| CN108233392A (en) * | 2018-01-24 | 2018-06-29 | 中国矿业大学(北京) | Based on Advanced Static Var Compensator of the cascade without bridging current circuit |
| CN108063445A (en) * | 2018-01-24 | 2018-05-22 | 中国矿业大学(北京) | Advanced Static Var Compensator based on Mixed cascading bridge-type convertor circuit |
| CN108306310A (en) * | 2018-01-24 | 2018-07-20 | 中国矿业大学(北京) | Advanced Static Var Compensator based on cascade diode H bridges |
| CN108011379A (en) * | 2018-01-25 | 2018-05-08 | 中国矿业大学(北京) | Advanced Static Var Compensator based on single stage shift module level parallel-type inverter |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201766512U (en) * | 2010-08-24 | 2011-03-16 | 山东乐航节能科技股份有限公司 | Delta serial compensation type alternating-current voltage-stabilizing power supply |
| CN202218165U (en) * | 2011-08-18 | 2012-05-09 | 武汉钢铁(集团)公司 | A Parallel Electronic Power Transformer with Energy Feedback Function |
| CN103066871A (en) * | 2013-01-15 | 2013-04-24 | 中国矿业大学(北京) | High power cascade type diode H-bridge unit power factor rectifier |
| CN103441504A (en) * | 2013-08-15 | 2013-12-11 | 东南大学 | Series compensation low-voltage ride-through device with self-charging function and control method thereof |
| CN203951375U (en) * | 2014-03-12 | 2014-11-19 | 中国矿业大学(北京) | High-power offset-type cascade diode H bridge Unity Power Factor PWM Rectifier Based |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100517927C (en) * | 2001-11-20 | 2009-07-22 | 王玉富 | Three-phase power supply parallel feedforward compensation power factor correction circuit |
-
2014
- 2014-03-12 CN CN201410090383.6A patent/CN103840684B/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201766512U (en) * | 2010-08-24 | 2011-03-16 | 山东乐航节能科技股份有限公司 | Delta serial compensation type alternating-current voltage-stabilizing power supply |
| CN202218165U (en) * | 2011-08-18 | 2012-05-09 | 武汉钢铁(集团)公司 | A Parallel Electronic Power Transformer with Energy Feedback Function |
| CN103066871A (en) * | 2013-01-15 | 2013-04-24 | 中国矿业大学(北京) | High power cascade type diode H-bridge unit power factor rectifier |
| CN103441504A (en) * | 2013-08-15 | 2013-12-11 | 东南大学 | Series compensation low-voltage ride-through device with self-charging function and control method thereof |
| CN203951375U (en) * | 2014-03-12 | 2014-11-19 | 中国矿业大学(北京) | High-power offset-type cascade diode H bridge Unity Power Factor PWM Rectifier Based |
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