CN205754048U - The distributed full-bridge MMC of auxiliary capacitor based on inequality constraints is from all pressing topology - Google Patents

Abstract

This utility model provides the distributed full-bridge MMC of auxiliary capacitor based on inequality constraints from all pressing topology.Full-bridge MMC is from all pressing topology, by full-bridge MMC model with from all pressure subsidiary loop joint mappings.Full-bridge MMC model and 6 in all pressure subsidiary loop is by subsidiary loopNIndividual IGBT module generation electrical link, IGBT module triggers, and both constitute the distributed full-bridge MMC of auxiliary capacitor based on inequality constraints from all pressing topology；IGBT module locking, topoligical equivalence is full-bridge MMC topology.This full-bridge MMC is from all pressing topology, DC side fault can be clamped, do not rely on special Pressure and Control simultaneously, can be on the basis of completing the conversion of alternating current-direct current energy, spontaneously realize the equilibrium of submodule capacitor voltage, submodule can be reduced simultaneously accordingly and trigger frequency and capacitor's capacity, it is achieved the fundamental frequency modulation of full-bridge MMC.

Description

The distributed full-bridge MMC of auxiliary capacitor based on inequality constraints is from all pressing topology

Technical field

This utility model relates to flexible transmission field, is specifically related to a kind of auxiliary capacitor based on inequality constraints distributed Full-bridge MMC is from all pressing topology.

Background technology

Modularization multi-level converter MMC is the developing direction of following HVDC Transmission Technology, and MMC uses submodule (Sub- Module, SM) mode that cascades constructs converter valve, it is to avoid the directly series connection of big metering device, reduce device conforming Requirement, simultaneously facilitates dilatation and redundant configuration.Along with the rising of level number, output waveform, close to sinusoidal, can effectively avoid low electricity The defect of flat VSC-HVDC.

Full-bridge MMC is combined by full-bridge submodule, full-bridge submodule by four IGBT module, a sub-module capacitance and 1 mechanical switch is constituted, and flexible operation has DC Line Fault clamping ability.

Different from two level, three level VSC, the DC voltage of full-bridge MMC is not supported by a bulky capacitor, but by A series of separate suspension submodule capacitances in series support.In order to ensure waveform quality and the guarantee that AC voltage exports In module, each power semiconductor bears identical stress, also for preferably supporting DC voltage, reduces alternate circulation, must Must ensure that submodule capacitor voltage is in the state of dynamic stability at the periodic current disorder of internal organs of brachium pontis power.

Sequence based on capacitance voltage sequence all presses algorithm to be to solve the equilibrium of full-bridge MMC Neutron module capacitance voltage at present to ask The main flow thinking of topic.But, the realization of ranking function has to rely on the Millisecond sampling of capacitance voltage, needs substantial amounts of sensor And optical-fibre channel is coordinated；Secondly, when group number of modules increases, the operand of capacitance voltage sequence increases rapidly, for The hardware designs of controller brings huge challenge；Additionally, submodule is cut-off frequency and has the highest by sequence all realizations of pressure algorithm Requirement, cut-off frequency with all pressure effect be closely related, in practice process, probably due to all press the restriction of effect, it has to Improve the triggering frequency of submodule, and then bring the increase that inverter is lost.

Document " A DC-Link Voltage Self-Balance Method for a Diode-Clamped Modular Multilevel Converter With Minimum Number of Voltage Sensors ", it is proposed that one Plant the thinking relying on clamp diode and transformator to realize the equilibrium of MMC submodule capacitor voltage.But the program in design Determining degree and destroy the modular nature of submodule, submodule capacitive energy interchange channel is also confined in mutually, could not be fully sharp With the existing structure of MMC, introducing of three transformators also brings along bigger being transformed into while making control strategy complicate This.

Utility model content

For the problems referred to above, the purpose of this utility model is to propose a kind of economy, modular, is independent of all pressing calculation Method, can reduce submodule simultaneously accordingly and trigger frequency and capacitor's capacity and have the full-bridge MMC of DC Line Fault clamping ability from all Pressure topology.

The concrete constituted mode of this utility model is as follows.

The distributed full-bridge MMC of auxiliary capacitor based on inequality constraints is from all pressing topology, including be made up of A, B, C three-phase Full-bridge MMC model, each brachium pontis of A, B, C three-phase respectively byNIndividual full-bridge submodule and 1 brachium pontis reactor are in series；Including By 6NIndividual IGBT module, 6N+ 11 clamp diodes, 8 auxiliary capacitors, 4 auxiliary IGBT module compositions from the most all pressing auxiliary Loop.

The above-mentioned distributed full-bridge MMC of auxiliary capacitor based on inequality constraints is from all pressing topology, in full-bridge MMC model, and A phase 1st submodule of upper brachium pontis, one IGBT module midpoint is upwards connected with dc bus positive pole, another IGBT module Midpoint is connected with one IGBT module midpoint of the 2nd submodule of brachium pontis in A phase downwards；In A phase the of brachium pontisiIndividual submodule Block, whereiniValue be 2～N-1, one IGBT module midpoint is upwards with in A phase the of brachium pontisi-1 submodule one IGBT module midpoint is connected, and another IGBT module midpoint is downwards with in A phase the of brachium pontisiOne IGBT module of+1 submodule Midpoint is connected；In A phase the of brachium pontisNIndividual submodule, one IGBT module midpoint down through two brachium pontis reactors with under A phase One IGBT module midpoint of the 1st submodule of brachium pontis is connected, and another IGBT module midpoint is upwards with in A phase the of brachium pontisNOne IGBT module midpoint of-1 submodule is connected；The of the lower brachium pontis of A phaseiIndividual submodule, whereiniValue be 2～N-1, The of one IGBT module midpoint upwards brachium pontis lower with A phaseiOne IGBT module midpoint of-1 submodule is connected, another IGBT module midpoint downwards with the of A phase time brachium pontisiOne IGBT module midpoint of+1 submodule is connected；The of the lower brachium pontis of A phaseN Individual submodule, one IGBT module midpoint is connected with dc bus negative pole downwards, another IGBT module midpoint upwards with A Descend the of brachium pontis mutuallyNTwo IGBT module midpoints of-1 submodule are connected.B phase and the connection side of C phase upper and lower bridge arm submodule Formula is consistent with A.

The above-mentioned distributed full-bridge MMC of auxiliary capacitor based on inequality constraints is from all pressing topology, in all pressure subsidiary loops, First auxiliary capacitor and second auxiliary capacitor are in parallel by clamp diode, and second auxiliary capacitor positive pole connects auxiliary IGBT module, first auxiliary capacitor negative pole connects clamp diode and is incorporated to dc bus positive pole；3rd auxiliary capacitor and Four auxiliary capacitors are in parallel by clamp diode, and the 3rd auxiliary capacitor negative pole connects auxiliary IGBT module, the 4th auxiliary Capacitance cathode connects clamp diode and is incorporated to dc bus negative pole；5th auxiliary capacitor and the 6th auxiliary capacitor pass through clamper Diodes in parallel, the 5th auxiliary capacitor positive pole connects auxiliary IGBT module, and the 6th auxiliary capacitor negative pole connects clamper two pole Pipe is incorporated to dc bus positive pole；7th auxiliary capacitor and the 8th auxiliary capacitor are in parallel by clamp diode, and the 8th auxiliary Helping electric capacity negative pole to connect auxiliary IGBT module, the 7th auxiliary capacitor positive pole connects clamp diode and is incorporated to dc bus negative pole. Clamp diode, by the 1st sub-module capacitance and first auxiliary capacitor positive pole in brachium pontis in IGBT module connection A phase；Logical Cross IGBT module and connect in A phase in brachium pontis theiIndividual sub-module capacitance and thei+ 1 sub-module capacitance positive pole, whereiniValue be 1～N-1；The is connected in A phase in brachium pontis by IGBT moduleNIndividual sub-module capacitance brachium pontis 1st sub-module capacitance lower with A phase is just Pole；The is connected in the lower brachium pontis of A phase by IGBT moduleiThe lower brachium pontis of individual sub-module capacitance and A phase thei+ 1 sub-module capacitance is just Pole, whereiniValue be 1～N-1；The is connected in the lower brachium pontis of A phase by IGBT moduleNIndividual sub-module capacitance and the 3rd auxiliary Capacitance cathode.Clamp diode, by the 1st sub-module capacitance and second auxiliary electricity in brachium pontis in IGBT module connection B phase Hold negative pole；The is connected in B phase in brachium pontis by IGBT moduleiIndividual sub-module capacitance and thei+ 1 sub-module capacitance negative pole, whereiniValue be 1～N-1；The is connected in B phase in brachium pontis by IGBT moduleNIndividual sub-module capacitance brachium pontis 1st son lower with B phase Module capacitance negative pole；The is connected in the lower brachium pontis of B phase by IGBT moduleiThe lower brachium pontis of individual sub-module capacitance and B phase thei+ 1 submodule Block electric capacity negative pole, whereiniValue be 2～N-1；The is connected in the lower brachium pontis of B phase by IGBT moduleNIndividual sub-module capacitance and the Four auxiliary capacitor negative poles.When between C phase upper and lower bridge arm Neutron module, the connected mode of clamp diode is consistent with A, the 6th Auxiliary capacitor positive pole is the sub-module capacitance positive pole of brachium pontis first in auxiliary IGBT module, clamp diode connection C phase, the 5th Auxiliary capacitor negative pole is the sub-module capacitance negative pole of brachium pontis first in auxiliary IGBT module, clamp diode connection B phase, the 8th Auxiliary capacitor positive pole connects the lower brachium pontis of C phase the through auxiliary IGBT module, clamp diodeNIndividual sub-module capacitance positive pole, the 7th Auxiliary capacitor negative pole connects the lower brachium pontis of B phase the through auxiliary IGBT module, clamp diodeNIndividual sub-module capacitance negative pole；In C phase When between lower brachium pontis Neutron module, the connected mode of clamp diode is consistent with B, the 5th auxiliary capacitor negative pole is through auxiliary IGBT Module, clamp diode connect the sub-module capacitance negative pole of brachium pontis first in C phase, and the 6th auxiliary capacitor positive pole is through auxiliary IGBT Module, clamp diode connect the sub-module capacitance positive pole of brachium pontis first in A phase, and the 7th auxiliary capacitor negative pole is through auxiliary IGBT Module, clamp diode connect the lower brachium pontis of C phase theNIndividual sub-module capacitance negative pole, the 8th auxiliary capacitor positive pole is through auxiliary IGBT Module, clamp diode connect the lower brachium pontis of A phase theNIndividual sub-module capacitance positive pole.

Accompanying drawing explanation

Fig. 1 is the structural representation of full-bridge submodule；

Fig. 2 is that the distributed full-bridge MMC of auxiliary capacitor based on inequality constraints is from all pressing topology.

Detailed description of the invention

For of the present utility model performance and operation principle are expanded on further, below in conjunction with accompanying drawing to the composition to utility model Mode is specifically described with operation principle.But full-bridge MMC based on this principle is not limited to Fig. 2 from all pressure topologys.

With reference to Fig. 2, the distributed full-bridge MMC of auxiliary capacitor based on inequality constraints from all pressing topology, including by A, B, C tri- The full-bridge MMC model constituted mutually, each brachium pontis of A, B, C three-phase respectively byNIndividual full-bridge submodule and the series connection of 1 brachium pontis reactor and Become, including by 6NIndividual IGBT module, 6N+ 11 clamp diodes, 8 auxiliary capacitors, 4 assist the most equal of IGBT module composition Pressure subsidiary loop.

In full-bridge MMC model, the 1st submodule of brachium pontis in A phase, one IGBT module midpoint upwards with dc bus Positive pole is connected, and another IGBT module midpoint is connected with one IGBT module midpoint of the 2nd submodule of brachium pontis in A phase downwards Connect；In A phase the of brachium pontisiIndividual submodule, whereiniValue be 2 ~N-1, one IGBT module midpoint upwards with bridge in A phase The of armiOne IGBT module midpoint of-1 submodule is connected, and another IGBT module midpoint is downwards with in A phase the of brachium pontisiOne IGBT module midpoint of+1 submodule is connected；In A phase the of brachium pontisNIndividual submodule, one IGBT module midpoint to Upper with in A phase the of brachium pontisNOne IGBT module midpoint of-1 submodule is connected, and another IGBT module midpoint is down through two Individual brachium pontis reactorL ₀One IGBT module midpoint of the 1st full-bridge submodule of brachium pontis lower with A phase is connected；The lower brachium pontis of A phase TheiIndividual submodule, whereiniValue be 2 ~N-1, the of one IGBT module midpoint upwards brachium pontis lower with A phasei-1 submodule One IGBT module midpoint of block is connected, another IGBT module midpoint downwards with the of A phase time brachium pontisi+ 1 submodule one IGBT module midpoint is connected；The of the lower brachium pontis of A phaseNIndividual submodule, one IGBT module midpoint is born with dc bus downwards Pole is connected, the of another IGBT module midpoint upwards brachium pontis lower with A phaseNOne IGBT module midpoint of-1 submodule is connected Connect.The connected mode of B phase and C phase upper and lower bridge arm submodule is consistent with A.

From all pressing in subsidiary loop, auxiliary capacitorC ₁With auxiliary capacitorC ₂In parallel by clamp diode, auxiliary capacitorC ₂Just Pole connects auxiliary IGBT moduleT ₁, auxiliary capacitorC ₁Negative pole connects clamp diode and is incorporated to dc bus positive pole；Auxiliary capacitorC ₃With Auxiliary capacitorC ₄In parallel by clamp diode, auxiliary capacitorC ₃Negative pole connects auxiliary IGBT moduleT ₂, auxiliary capacitorC ₄Positive pole is even Connect clamp diode and be incorporated to dc bus negative pole；Auxiliary capacitorC ₅With auxiliary capacitorC ₆In parallel by clamp diode, auxiliary capacitorC ₅Positive pole connects auxiliary IGBT moduleT ₃, auxiliary capacitorC ₆Negative pole connects clamp diode and is incorporated to dc bus positive pole；Auxiliary capacitorC ₇With auxiliary capacitorC ₈In parallel by clamp diode, auxiliary capacitorC ₈Negative pole connects auxiliary IGBT moduleT ₄, auxiliary capacitorC ₇Just Pole connects clamp diode and is incorporated to dc bus negative pole.Clamp diode, passes through IGBT moduleT _{au_1}Connect in A phase in brachium pontis the 1 sub-module capacitanceC _{au_1}With auxiliary capacitorC ₁Positive pole；Pass through IGBT moduleT _{au_i} 、T _{au_i+1}Connect in A phase in brachium pontis theiHeight Module capacitanceC _{au_i} Withi+ 1 sub-module capacitanceC _{au_i+1}Positive pole, whereiniValue be 1～N-1；Pass through IGBT moduleT _{au_N} 、T _{al_1}Connect in A phase in brachium pontis theNIndividual sub-module capacitanceC _{au_N} Brachium pontis 1st sub-module capacitance lower with A phaseC _{al_1}Positive pole；Pass through IGBT module T_{al_i} 、T _{al_i+1}Connect in the lower brachium pontis of A phase theiIndividual sub-module capacitanceC _{al_i} Brachium pontis lower with A phase thei+ 1 submodule electricity HoldC _{al_i+1}Positive pole, whereiniValue be 1～N-1；Pass through IGBT moduleT _{al_N} Connect in the lower brachium pontis of A phase theNIndividual submodule electricity HoldC _{al_N} With auxiliary capacitorC ₃Positive pole.Clamp diode, passes through IGBT moduleT _{bu_1}1st submodule electricity in brachium pontis in connection B phase HoldC _{bu_1}With auxiliary capacitorC ₂, auxiliary capacitorC ₅Negative pole；Pass through IGBT moduleT _{bu_i} 、T _{bu_i+1}Connect in B phase in brachium pontis theiHeight Module capacitanceC _{bu_i} Withi+ 1 sub-module capacitanceC _{bu_i+1}Negative pole, whereiniValue be 1～N-1；Pass through IGBT moduleT _{bu_N} 、T _{bl_1}Connect in B phase in brachium pontis theNIndividual sub-module capacitanceC _{bu_N} Brachium pontis 1st sub-module capacitance lower with B phaseC _{bl_1}Negative pole；Pass through IGBT moduleT _{bl_i} 、T _{bl_i+1}Connect in the lower brachium pontis of B phase theiIndividual sub-module capacitanceC _{bl_i} Brachium pontis lower with B phase thei+ 1 submodule electricity HoldC _{bl_i+1}Negative pole, whereiniValue be 1～N-1；Pass through IGBT moduleT _{bl_N} Connect in the lower brachium pontis of B phase theNIndividual submodule electricity HoldC _{bl_N} With auxiliary capacitorC ₄, auxiliary capacitorC ₇Negative pole.Auxiliary capacitorC ₆Positive pole is through auxiliary IGBT moduleT _{cu_1}, clamp diode even Connect first sub-module capacitance of brachium pontis in C phaseC _{cu_1}Positive pole；Auxiliary capacitorC ₈Positive pole is through auxiliary IGBT moduleT _{cl_N} , clamper two pole Pipe connects the lower brachium pontis of C phase theNIndividual sub-module capacitanceC _{cl_N} Positive pole.

Under normal circumstances, from the most all pressure subsidiary loop in 6NIndividual IGBT moduleT _{au_i} 、T _{al_i} 、T _{bu_i}、T _{bl_i} 、T _{cu_i} 、T _{cl_i} Often Close, whereiniValue be 1～N, first sub-module capacitance of brachium pontis in A phaseC _{au_1}During bypass, now assist IGBT moduleT ₁Disconnected Open, submodule electric capacityC _{au_1}With auxiliary capacitorC ₁In parallel by clamp diode；Brachium pontis in A phaseiIndividual sub-module capacitanceC _{au_i} Other Lu Shi, whereiniValue be 2～N, submodule electric capacityC _{au_i} With submodule electric capacityC _{au_i-1}In parallel by clamp diode；A phase First sub-module capacitance of lower brachium pontisC _{al_1}During bypass, submodule electric capacityC _{al_1}By clamp diode, two brachium pontis reactorsL ₀ With submodule electric capacityC _{au_N} In parallel；The lower brachium pontis of A phase theiIndividual sub-module capacitanceC _{al_i} During bypass, whereiniValue be 2～N, submodule Block electric capacityC _{al_i} With submodule electric capacityC _{al_i-1}In parallel by clamp diode；Auxiliary IGBT moduleT ₂During Guan Bi, auxiliary capacitorC ₃ By clamp diode and submodule electric capacityC _{al_N} In parallel.

Under normal circumstances, from the most all pressure subsidiary loop in 6NIndividual IGBT moduleT _{au_i} 、T _{al_i} 、T _{bu_i}、T _{bl_i} 、T _{cu_i} 、T _{cl_i} Often Close, whereiniValue be 1～N, assist IGBT moduleT ₁During Guan Bi, auxiliary capacitorC ₂With submodule electric capacityC _{bu_1}By clamper two Pole pipe is in parallel；Brachium pontis in B phaseiIndividual sub-module capacitanceC _{bu_i} During bypass, whereiniValue be 1～N-1, submodule electric capacityC _{bu_i} With submodule electric capacityC _{bu_i+1}In parallel by clamp diode；Brachium pontis in B phaseNIndividual sub-module capacitanceC _{bu_N} During bypass, submodule Electric capacityC _{bu_N} By clamp diode, two brachium pontis reactorsL ₀With submodule electric capacityC _{bl_1}In parallel；The lower brachium pontis of B phase theiIndividual submodule Block electric capacityC _{bl_i} During bypass, whereiniValue be 1～N-1, submodule electric capacityC _{bl_i} With submodule electric capacityC _{bl_i+1}By clamper two Pole pipe is in parallel；The lower brachium pontis of B phase theNIndividual sub-module capacitanceC _{bl_N} During bypass, submodule electric capacityC _{bl_N} With auxiliary capacitorC ₄Pass through clamper Diodes in parallel.Wherein assist IGBT moduleT ₁Triggering signal and first submodule of brachium pontis in A phase to trigger signal consistent；Auxiliary Help IGBT moduleT ₂The lower brachium pontis of triggering signal and B phase theNThe triggering signal of individual submodule is consistent.

During orthogonal stream energy is changed, each submodule alternately puts into, bypass, assists IGBT moduleT ₁、T ₂Alternately Guan Bi, shutoff, A, B phase upper and lower bridge arm submodule capacitor voltage, under the effect of clamp diode, meets and descends column constraint:

Due to auxiliary capacitorC ₁、C ₂、C ₃、C ₄The relation of voltage meets:

In like manner, B, C phase upper and lower bridge arm submodule capacitor voltage meets following condition:

Due to auxiliary capacitorC ₅、C ₆、C ₇、C ₈The relation of voltage meets:

It follows that at single clamp MMC in the dynamic process completing the conversion of orthogonal stream energy, meet following constraint bar Part:

Being illustrated from above-mentioned, this full-bridge MMC topology possesses submodule capacitor voltage from the ability of equalization.

Finally should be noted that: described embodiment is only some embodiments of the present application rather than whole realities Execute example.Based on the embodiment in the application, those of ordinary skill in the art are obtained under not making creative work premise Every other embodiment, broadly fall into the application protection scope.

Claims (4)

1. the distributed full-bridge MMC of auxiliary capacitor based on inequality constraints is from all pressing topology, it is characterised in that: include by A, B, C Three-phase constitute full-bridge MMC model, each brachium pontis of A, B, C three-phase respectively byNIndividual full-bridge submodule and 1 brachium pontis reactor series connection Form；Including by 6NIndividual IGBT module, 6N+ 11 clamp diodes, 8 auxiliary capacitorsC ₁、C ₂、C ₃、C ₄、C ₅、C ₆、C ₇、C ₈, 4 Auxiliary IGBT moduleT ₁、T ₂、T ₃、T ₄Constitute the most all presses subsidiary loop.

The distributed full-bridge MMC of auxiliary capacitor based on inequality constraints the most according to claim 1 is from all pressing topology, and it is special Levy and be: in full-bridge MMC model, the 1st submodule of brachium pontis in A phase, one IGBT module midpoint upwards with dc bus Positive pole is connected, and another IGBT module midpoint is connected with one IGBT module midpoint of the 2nd submodule of brachium pontis in A phase downwards Connect；In A phase the of brachium pontisiIndividual submodule, whereiniValue be 2 ~N-1, one IGBT module midpoint upwards with bridge in A phase The of armiOne IGBT module midpoint of-1 submodule is connected, and another IGBT module midpoint is downwards with in A phase the of brachium pontisiOne IGBT module midpoint of+1 submodule is connected；In A phase the of brachium pontisNIndividual submodule, one IGBT module midpoint to Upper with in A phase the of brachium pontisNOne IGBT module midpoint of-1 submodule is connected, and another IGBT module midpoint is down through two Individual brachium pontis reactorL ₀One IGBT module midpoint of the 1st full-bridge submodule of brachium pontis lower with A phase is connected；The lower brachium pontis of A phase TheiIndividual submodule, whereiniValue be 2 ~N-1, the of one IGBT module midpoint upwards brachium pontis lower with A phasei-1 submodule One IGBT module midpoint of block is connected, another IGBT module midpoint downwards with the of A phase time brachium pontisi+ 1 submodule one IGBT module midpoint is connected；The of the lower brachium pontis of A phaseNIndividual submodule, one IGBT module midpoint is born with dc bus downwards Pole is connected, the of another IGBT module midpoint upwards brachium pontis lower with A phaseNOne IGBT module midpoint of-1 submodule is connected Connect；The connected mode of B phase and C phase upper and lower bridge arm submodule is consistent with A；At A, B, C phase upper and lower bridge armiIndividual submodule Mechanical switch it is parallel with respectively up and down between output leadK _{au_i} ,K _{al_i} ,K _{bu_i} ,K _{bl_i} ,K _{cu_i} ,K _{cl_i} , whereiniValue be 1 ~N； A, B, C three-phase status that above-mentioned annexation is constituted is consistent.

The distributed full-bridge MMC of auxiliary capacitor based on inequality constraints the most according to claim 1 is from all pressing topology, and it is special Levy and be: in all pressure subsidiary loops, auxiliary capacitorC ₁With auxiliary capacitorC ₂In parallel by clamp diode, auxiliary capacitorC ₂Just Pole connects auxiliary IGBT moduleT ₁, auxiliary capacitorC ₁Negative pole connects clamp diode and is incorporated to dc bus positive pole；Auxiliary capacitorC ₃With Auxiliary capacitorC ₄In parallel by clamp diode, auxiliary capacitorC ₃Negative pole connects auxiliary IGBT moduleT ₂, auxiliary capacitorC ₄Positive pole is even Connect clamp diode and be incorporated to dc bus negative pole；Auxiliary capacitorC ₅With auxiliary capacitorC ₆In parallel by clamp diode, auxiliary capacitorC ₅Positive pole connects auxiliary IGBT moduleT ₃, auxiliary capacitorC ₆Negative pole connects clamp diode and is incorporated to dc bus positive pole；Auxiliary capacitorC ₇With auxiliary capacitorC ₈In parallel by clamp diode, auxiliary capacitorC ₈Negative pole connects auxiliary IGBT moduleT ₄, auxiliary capacitorC ₇Just Pole connects clamp diode and is incorporated to dc bus negative pole；Clamp diode, passes through IGBT moduleT _{au_1}Connect in A phase in brachium pontis the 1 sub-module capacitanceC _{au_1}With auxiliary capacitorC ₁Positive pole；Pass through IGBT moduleT _{au_i} 、T _{au_i+1}Connect in A phase in brachium pontis theiHeight Module capacitanceC _{au_i} Withi+ 1 sub-module capacitanceC _{au_i+1}Positive pole, whereiniValue be 1～N-1；Pass through IGBT moduleT _{au_N} 、T _{al_1}Connect in A phase in brachium pontis theNIndividual sub-module capacitanceC _{au_N} Brachium pontis 1st sub-module capacitance lower with A phaseC _{al_1}Positive pole；Pass through IGBT module T_{al_i} 、T _{al_i+1}Connect in the lower brachium pontis of A phase theiIndividual sub-module capacitanceC _{al_i} Brachium pontis lower with A phase thei+ 1 submodule electricity HoldC _{al_i+1}Positive pole, whereiniValue be 1～N-1；Pass through IGBT moduleT _{al_N} Connect in the lower brachium pontis of A phase theNIndividual submodule electricity HoldC _{al_N} With auxiliary capacitorC ₃Positive pole；Clamp diode, passes through IGBT moduleT _{bu_1}1st submodule electricity in brachium pontis in connection B phase HoldC _{bu_1}With auxiliary capacitorC ₂Negative pole；Pass through IGBT moduleT _{bu_i} 、T _{bu_i+1}Connect in B phase in brachium pontis theiIndividual sub-module capacitanceC _{bu_i} Withi+ 1 sub-module capacitanceC _{bu_i+1}Negative pole, whereiniValue be 1～N-1；Pass through IGBT moduleT _{bu_N} 、T _{bl_1}Connect In B phase in brachium pontisNIndividual sub-module capacitanceC _{bu_N} Brachium pontis 1st sub-module capacitance lower with B phaseC _{bl_1}Negative pole；Pass through IGBT moduleT _{bl_i} 、T _{bl_i+1}Connect in the lower brachium pontis of B phase theiIndividual sub-module capacitanceC _{bl_i} Brachium pontis lower with B phase thei+ 1 sub-module capacitanceC _{bl_i+1} Negative pole, whereiniValue be 1～N-1；Pass through IGBT moduleT _{bl_N} Connect in the lower brachium pontis of B phase theNIndividual sub-module capacitanceC _{bl_N} With Auxiliary capacitorC ₄Negative pole；When between C phase upper and lower bridge arm Neutron module, the connected mode of clamp diode is consistent with A, auxiliary capacitorC ₆ Positive pole is through IGBT moduleT _{cu_1}, clamp diode connect first sub-module capacitance of brachium pontis in C phaseC _{cu_1}Positive pole, auxiliary capacitorC ₅ Negative pole is through IGBT moduleT _{bu_1}, clamp diode connect first sub-module capacitance of brachium pontis in B phaseC _{bu_1}Negative pole, auxiliary capacitorC ₈ Positive pole is through IGBT moduleT _{cl_N} , clamp diode connect the lower brachium pontis of C phase theNIndividual sub-module capacitanceC _{cl_N} Positive pole, auxiliary capacitorC ₇Negative Pole is through IGBT moduleT _{bl_N} , clamp diode connect the lower brachium pontis of B phase theNIndividual sub-module capacitanceC _{bl_N} Negative pole；In C phase upper and lower bridge arm When between submodule, the connected mode of clamp diode is consistent with B, auxiliary capacitorC ₅Negative pole is through IGBT moduleT _{cu_1}, clamper two pole Pipe connects first sub-module capacitance of brachium pontis in C phaseC _{cu_1}Negative pole, auxiliary capacitorC ₆Positive pole is through IGBT moduleT _{au_1}, clamper two pole Pipe connects first sub-module capacitance of brachium pontis in A phaseC _{au_1}Positive pole, auxiliary capacitorC ₇Negative pole is through IGBT moduleT _{cl_N} , clamper two pole Pipe connects the lower brachium pontis of C phase theNIndividual sub-module capacitanceC _{cl_N} Negative pole, auxiliary capacitorC ₈Positive pole is through IGBT moduleT _{al_N} , clamp diode Connect the lower brachium pontis of A phase theNIndividual sub-module capacitanceC _{al_N} Positive pole；In above-mentioned A, B, C three-phase 6NIndividual IGBT moduleT _{au_i} 、T _{al_i} 、T _{bu_i} 、T _{bl_i} 、T _{cu_i} 、T _{cl_i} , whereiniValue be 1～N, 6N+ 11 clamp diodes, 8 auxiliary capacitorsC ₁、C ₂、C ₃、C ₄、C ₅、C ₆、C ₇、C ₈And 4 auxiliary IGBT moduleT ₁、T ₂、T ₃、T ₄, collectively form from all pressing subsidiary loop.

The distributed full-bridge MMC of auxiliary capacitor based on inequality constraints the most according to claim 1 is from all pressing topology, and it is special Levy and be: during normal condition, from the most all pressure subsidiary loop in 6NIndividual IGBT moduleT _{au_i} 、T _{al_i} 、T _{bu_i} 、T _{bl_i} 、T _{cu_i} 、T _{cl_i} Often Close, during failure condition, 6NIndividual IGBT moduleT _{au_i} 、T _{al_i} 、T _{bu_i} 、T _{bl_i} 、T _{cu_i} 、T _{cl_i} Disconnect, whereiniValue be 1～N； Under normal circumstances, first sub-module capacitance of brachium pontis in A phaseC _{au_1}During bypass, now assist IGBT moduleT ₁Disconnect, submodule electricity HoldC _{au_1}With auxiliary capacitorC ₁In parallel by clamp diode；Brachium pontis in A phaseiIndividual sub-module capacitanceC _{au_i} During bypass, whereini Value be 2～N, submodule electric capacityC _{au_i} With submodule electric capacityC _{au_i-1}In parallel by clamp diode；The lower brachium pontis first of A phase Individual sub-module capacitanceC _{al_1}During bypass, submodule electric capacityC _{al_1}By clamp diode, two brachium pontis reactorsL ₀With submodule electricity HoldC _{au_N} In parallel；The lower brachium pontis of A phase theiIndividual sub-module capacitanceC _{al_i} During bypass, whereiniValue be 2～N, submodule electric capacityC _{al_i} With submodule electric capacityC _{al_i-1}In parallel by clamp diode；Auxiliary IGBT moduleT ₂During Guan Bi, auxiliary capacitorC ₃By clamper two Pole pipe and submodule electric capacityC _{al_N} In parallel；Auxiliary IGBT moduleT ₁During Guan Bi, auxiliary capacitorC ₂With submodule electric capacityC _{bu_1}By pincers Position diodes in parallel；Brachium pontis in B phaseiIndividual sub-module capacitanceC _{bu_i} During bypass, whereiniValue be 1～N-1, submodule electricity HoldC _{bu_i} With submodule electric capacityC _{bu_i+1}In parallel by clamp diode；Brachium pontis in B phaseNIndividual sub-module capacitanceC _{bu_N} During bypass, Submodule electric capacityC _{bu_N} By clamp diode, two brachium pontis reactorsL ₀With submodule electric capacityC _{bl_1}In parallel；The lower brachium pontis of B phase thei Individual sub-module capacitanceC _{bl_i} During bypass, whereiniValue be 1～N-1, submodule electric capacityC _{bl_i} With submodule electric capacityC _{bl_i+1}Pass through Clamp diode is in parallel；The lower brachium pontis of B phaseNIndividual sub-module capacitanceC _{bl_N} During bypass, submodule electric capacityC _{bl_N} With auxiliary capacitorC ₄Pass through Clamp diode is in parallel；Wherein assist IGBT moduleT ₁Trigger signal and the triggering signal of first submodule of brachium pontis in A phase Unanimously；Auxiliary IGBT moduleT ₂The lower brachium pontis of triggering signal and B phase theNThe triggering signal of individual submodule is consistent；At straight alternating current energy During amount conversion, each submodule alternately puts into, bypass, assists IGBT moduleT ₁、T ₂Being alternately closed, turn off, A phase is upper and lower Brachium pontis submodule capacitor voltage, under the effect of clamp diode, meets lower column constraint,U _C1≥U _{Cau_1}≥U _{Cau_2}…≥U _{Cau_N} ≥U _{Cal_1}≥U _{Cal_2}…≥U _{Cal_N} ≥U _C3；B phase upper and lower bridge arm submodule capacitor voltage is under the effect of clamp diode, under meeting Column constraint,U _C2≤U _{Cbu_1}≤U _{Cbu_2}…≤U _{Cbu_N} ≤U _{Cbl_1}≤U _{Cbl_2}…≤U _{Cbl_N} ≤U _C4；Against auxiliary capacitorC ₁、C ₂Electricity Between pressure, auxiliary capacitorC ₃、C ₄Two inequality constraints between voltage,U _C1≤U _C2,U _C3≥U _C4, the 4 of A, B phase upper and lower bridge armN Individual sub-module capacitance,C _{au_i} 、C _{al_i} 、C _{bu_i} 、C _{bl_i} , whereiniValue be 1～N, and auxiliary capacitorC ₁、C ₂、C ₃、C ₄, voltage Being in self-balancing state, A, B of topology are alternate possesses submodule capacitor voltage from the ability of equalization；If the composition shape of C phase in topology Formula is consistent with A, then pass through auxiliary capacitorC ₅、C ₆、C ₇、C ₈Effect, between constraints and A, B of C, B capacitive coupling voltage Capacitance voltage constraints is similar to；If the form of the composition of C phase is consistent with B in topology, then pass through auxiliary capacitorC ₅、C ₆、C ₇、C ₈ Effect, the constraints of A, C capacitive coupling voltage is similar with capacitance voltage constraints between A, B.