CN102594190B - Square wave pulse circulation modulating method for modular multilevel converter - Google Patents
Square wave pulse circulation modulating method for modular multilevel converter Download PDFInfo
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Abstract
The invention discloses a square wave pulse circulation modulating method for a modular multilevel converter, belonging to the technical field of control on the multilevel converter. Under the premise that the output wave form of a synthesis step wave is not changed, the traditional square wave pulse is corrected and optimized according to the topology structure and the working principle of the modular multilevel converter; according to a certain sequence and a switching period, circulation and inverse-regulation judgment are conducted; and the obtained square wave pulse circulation sequence, as final drive pulse, is used for realizing control on the modular multilevel converter. Without any capacitor voltage control measures, the square wave pulse circulation modulating method can realize the equal distribution of active energy among all the power units of the modular multilevel converter as well as the balancing of direct-current capacitor voltage.
Description
Technical field
The invention belongs to multi-level converter control technology field, particularly a kind of square-wave pulse circulation modulating method of module combination multi-level converter.
Background technology
In recent years, multilevel technology is constantly promoted, and successful Application is at industrial circles such as high voltage direct current transmission, Electric Drive, active power filtering, static synchroballistic, common voltage-type multi-level converter topology is broadly divided into reed bit-type and the large class of unit cascaded type two at present.Module combination multi-level converter (Modular Multilevel Converter, MMC) as a kind of novel many level topologys, except having advantages of traditional multi-level converter, module combination multi-level converter adopts Modular Structure Design, is convenient to System Expansion and redundancy of effort; Have unbalanced operation ability, fault traversing and recovery capability, system reliability is high; Owing to having common DC bus, module combination multi-level converter is particularly useful for HVDC (High Voltage Direct Current) transmission system application.
Pulse modulation technique is one of important subject of module combination multi-level converter, and traditional Multilevel modulation technology comprises SPWM Technique (SPWM), space vector pulse width modulation (SVPWM), square-wave pulse modulation technique etc.Square-wave pulse modulation technique adopts staircase waveform to approach sinusoidal waveform, has the advantages such as low-order harmonic content is little, switching frequency is low, compares with SPWM, SVPWM technology, and square-wave pulse modulation technique is more suitable in the high-power applications occasion high to transducer effciency requirement.But when square-wave pulse modulation technique directly applies to MMC, will cause each power cell power output uneven, and when serious, cause system normally to work.
Summary of the invention
The present invention is directed to the square-wave pulse circulation modulating method that above-mentioned defect discloses a kind of module combination multi-level converter.The object of the invention is to overcome the limitation of traditional square wave pulse modulation technique.
A kind of square-wave pulse circulation modulating method of module combination multi-level converter comprises the following steps:
1) setting module combination multi-level converter contains 2n A phase power cell, a 2n B phase power cell and 2n C phase power cell, 2n the A phase power cell of 2n A phase power cell formation of n+1 A phase power cell to that is positioned at n A phase power cell of the 1st A phase power cell to the of brachium pontis and is positioned at lower brachium pontis, 2n the B phase power cell of 2n B phase power cell formation of n+1 B phase power cell to that is positioned at n B phase power cell of the 1st B phase power cell to the of brachium pontis and is positioned at lower brachium pontis, 2n the C phase power cell of 2n C phase power cell formation of n+1 C phase power cell to that is positioned at n C phase power cell of the 1st C phase power cell to the of brachium pontis and is positioned at lower brachium pontis, n is more than or equal to 1 positive integer,
S is A phase, B phase or C phase mutually, for 2n S phase power cell, and execution step 1) to step 3);
Carry out the calculating of square-wave pulse switching angle, form basic square-wave pulse: first according to the output level of module combination multi-level converter, count n+1, in calculating, in brachium pontis, for the synthesis of interchange, export the switching angle θ of staircase voltage
1-θ
n, to determine the start angle α of the basic square wave control impuls of 2n S phase power cell of the 1st S phase power cell to the
1-α
2nwith basic pulse width beta
1-β
2n, α wherein
d=θ
d, β
d=π-2 θ
d, d gets 1-n; α
e=π+θ
e-n, β
e=π-2 θ
e-n, e gets n+1 to 2n; Thereby formed basic square wave control impuls P corresponding to 2n S phase power cell of the 1st S phase power cell to the
1-P
2n;
2) pulse correction, to reduce basic square wave control impuls P
1-P
2nbetween difference in pulse width: guaranteeing under the constant prerequisite of synthetic staircase waveform output waveform, according to two principles to basic square wave control impuls P
1-P
2nstart angle α
1-α
2nwith basic pulse width beta
1-β
2nrevise, obtain optimization square-wave pulse P corresponding to 2n S phase power cell of the 1st S phase power cell to the
1'-P
2n'; Two principles are in dropping into the total equal principle of power cell of state in principle that square-wave pulse high level lasting time that in a power frequency period, 2n S phase power cell of the 1st S phase power cell to the is corresponding is equal and any time A phase brachium pontis, B phase brachium pontis and C phase brachium pontis;
3) to step 2) the middle optimization square-wave pulse P generating
1'-P
2n' circulate with switching cycle in the following sequence and judge anti-phase adjustment:
To optimizing square-wave pulse P
1'-P
2n' rearrange and generate the 1st combination-n and combine; The ordering of the 1st combination is P
1'-P
2n', the ordering of g combination is P
g'-P
n', P
1'-P
g-1', P
n+g'-P
2n', P
n+1'-P
n+g-1'; The ordering of n combination is P
n', P
1'-P
n-1', P
2n', P
n+1'-P
2n-1'; G is integer and meets 1 < g < n;
According to P
(g+l)' and P
(n+g+l-1)' exchange and anti-phase principle generation the 1st ' combination-n ' combination; The 1st ' ordering of combination is
the ordering of g ' combination is
the ordering of n ' combination is
l is integer and meets 0≤l≤n-1;
According to the 1st cyclic order that is incorporated into greatly the large combination of n, carry out the switching adjustment between each combination successively, and then obtain the final square wave driving pulse P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1"-P
2n"; The inner assembled arrangement order of the large combination of f is: f combination, f ' combination; F gets 1-n.
4) in module combination multi-level converter, determine the final square wave driving pulse P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1"-P
2n" after, by this final square wave driving pulse P
1"-P
2n" phase shift 2 π/3 and 4 π/3 obtain the final square wave driving pulse of all the other each power cells of two-phase respectively.
Described circulation and judge that the process of anti-phase adjustment is as follows:
Circulation is divided into two kinds of situations, the first situation refers to: at S, go up mutually each power cell of brachium pontis or S and descend mutually in the optimal control pulse cycle that each power cell inside of brachium pontis carries out, the high low logic level of respective pulses remains unchanged, when 1≤k≤n and 1≤j≤n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' and the final square wave driving pulse P of j S phase power cell afterwards that circulates
j" be consistent; When n+1≤k≤2n and n+1≤j≤2n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' and the final square wave driving pulse P of j S phase power cell afterwards that circulates
j" be consistent;
Second case refers to: at S, go up mutually each power cell of brachium pontis and S descends in the optimal control pulse cycle of carrying out between each power cell of brachium pontis mutually, the high low logic level of respective pulses is anti-phase, as 1≤k≤n and (n+1)≤and during j≤2n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' rp pulse and circulation after the final square wave driving pulse P of j S phase power cell
j" be consistent; When n+1≤k≤2n and 1≤j≤n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' rp pulse and circulation after the final square wave driving pulse P of j S phase power cell
j" be consistent;
In two kinds of situations of above-mentioned circulation, if i the optimization square-wave pulse P that S phase power cell is corresponding
i' after circulation, become m the final square wave driving pulse P that S phase power cell is corresponding
m", now, to i the optimization square-wave pulse P that S phase power cell is corresponding
i' carry out anti-phase processing, its complementary pulse
as m the final square wave driving pulse P that S phase power cell is corresponding
m"; I gets 1-n, and m gets n+1 to 2n;
In two kinds of situations of above-mentioned circulation, if t the optimization square-wave pulse P that S phase power cell is corresponding
t' after circulation, become u the final square wave driving pulse P that S phase power cell is corresponding
u", now, to t the optimization square-wave pulse P that S phase power cell is corresponding
t' carry out anti-phase processing, its complementary pulse
as u the final square wave driving pulse P that S phase power cell is corresponding
u"; U gets 1-n, and t gets n+1 to 2n.
The method that described square-wave pulse switching angle is calculated is equal-area method, specific subharmonic removing method.
In step 1) obtain the basic square wave control impuls P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1-P
2nafterwards, with basic square wave control impuls P
1-P
2nstep of replacing 3) the optimization square-wave pulse P in
1'-P
2n', then perform step 3), can obtain final square wave driving pulse P
1"-P
2n".
Beneficial effect of the present invention is: guaranteeing under the constant prerequisite of synthetic staircase waveform output waveform, without any capacitance voltage control measure, the present invention has realized the meritorious mean allocation of energy and the equilibrium of DC capacitor voltage between each power cell of MMC.
Accompanying drawing explanation
Fig. 1 is the structural representation of three-phase module combination multi-level converter;
Fig. 2 a is that module combination multi-level converter power cell drops into state the first schematic diagram;
Fig. 2 b is that module combination multi-level converter power cell drops into state the second schematic diagram;
Fig. 2 c is module combination multi-level converter power cell excision state the first schematic diagram;
Fig. 2 d is module combination multi-level converter power cell excision state the second schematic diagram;
Fig. 3 is the square-wave pulse circulation modulating method flow chart of module combination multi-level converter;
Fig. 4 a is the basic square-wave pulse schematic diagram of three level module combination multi-level converters;
Fig. 4 b is that first of three level module combination multi-level converters are optimized square-wave pulse schematic diagram;
Fig. 4 c is the first final square-wave pulse schematic diagram of three level module combination multi-level converters;
Fig. 5 a is that second of three level module combination multi-level converters are optimized square-wave pulse schematic diagram;
Fig. 5 b is the second final square-wave pulse schematic diagram of three level module combination multi-level converters;
Fig. 6 is the 3rd final square-wave pulse schematic diagram of the square-wave pulse circular modulating square wave of three level module combination multi-level converters;
Fig. 7 a is the interchange output phase voltage experimental waveform schematic diagram of three level module combination multi-level converters under the first embodiment;
Fig. 7 b is the DC capacitor voltage experimental waveform schematic diagram of three level module combination multi-level converters under the first embodiment;
Fig. 8 a is the interchange output phase voltage experimental waveform schematic diagram of three level module combination multi-level converters under the second embodiment;
Fig. 8 b is the DC capacitor voltage experimental waveform schematic diagram of three level module combination multi-level converters under the second embodiment.
Embodiment
By reference to the accompanying drawings embodiments of the present invention are described further:
Fig. 1 is the structural representation of (n+1) level three-phase module combination multi-level converter, and this module combination multi-level converter contains 2n A phase power cell, a 2n B phase power cell and 2n C phase power cell; N A phase power cell of the 1st A phase power cell to the is followed in series to form A and goes up mutually brachium pontis, and 2n A phase power cell of n+1 A phase power cell to the is followed in series to form A and descends mutually brachium pontis, and A phase brachium pontis is gone up mutually brachium pontis by A and descended mutually brachium pontis to form with A; A goes up mutually brachium pontis and A and descends mutually between brachium pontis and be connected with the second inductance 2 by the first inductance 1, and the common node between the first inductance 1 and the second inductance 2 is the first ac output end A;
N B phase power cell of the 1st B phase power cell to the is followed in series to form B and goes up mutually brachium pontis, and 2n B phase power cell of n+1 B phase power cell to the is followed in series to form B and descends mutually brachium pontis; B phase brachium pontis is gone up mutually brachium pontis by B and is descended mutually brachium pontis to form with B; B goes up mutually brachium pontis and B and descends mutually between brachium pontis and be connected with the 4th inductance 4 by the 3rd inductance 3, and the common node between the 3rd inductance 3 and the 4th inductance 4 is the second ac output end B;
N C phase power cell of the 1st C phase power cell to the is followed in series to form C and goes up mutually brachium pontis, and 2n C phase power cell of n+1 C phase power cell to the is followed in series to form C and descends mutually brachium pontis; C phase brachium pontis is gone up mutually brachium pontis by C and is descended mutually brachium pontis to form with C; C goes up mutually brachium pontis and C and descends mutually between brachium pontis and be connected with the 6th inductance 6 by the 5th inductance 5, and the common node between the 5th inductance 5 and the 6th inductance 6 is the 3rd ac output end C;
The first binding post of the 1st A phase power cell, the 1st B phase power cell and the 1st C phase power cell is connected and forms the anodal P of DC bus; The second binding post of 2n A phase power cell, a 2n B phase power cell and 2n C phase power cell is connected and forms DC bus negative pole N; N gets the positive integer that is more than or equal to 1.
Be illustrated in figure 2 the working state schematic representation of the power cell of module combination multi-level converter, in course of normal operation, the power cell of module combination multi-level converter has two kinds of operating states: Fig. 2 a and Fig. 2 b are the input view of MMC power cell, under input state, the first switch transistor T 1 or the first anti-paralleled diode D1 are open-minded, second switch pipe T2 turn-offs, and now power cell ac output end voltage all shows as DC capacitor voltage; When current i flows into power cell, as shown in Figure 2 a, current i flows into DC capacitor C by the first anti-paralleled diode D1, and to DC capacitor, C charges; When current i flows out power cell, as shown in Figure 2 b, current i flows out DC capacitor C by the first switch transistor T 1, and to DC capacitor, C discharges.
Fig. 2 c and Fig. 2 d are power cell excision view, and under excision state, second switch pipe T2 or the second anti-paralleled diode D2 are open-minded, and the first switch transistor T 1 is turn-offed, and now power cell ac output end voltage is zero; When current i flows out power cell, as shown in Figure 2 c, current i flows by the second anti-paralleled diode D2; When current i flows into power cell, as shown in Figure 2 d, current i flows by second switch pipe T2.
The square-wave pulse circulation modulating method flow chart that is illustrated in figure 3 a kind of module combination multi-level converter, the method specifically comprises the steps:
1) S is A phase, B phase or C phase mutually, for 2n S phase power cell, and execution step 1) to step 3);
Carry out the calculating of square-wave pulse switching angle, form basic square-wave pulse: first according to the output level of module combination multi-level converter, count n+1, in calculating, in brachium pontis, for the synthesis of interchange, export the switching angle θ of staircase voltage
1-θ
n, to determine the start angle α of the basic square wave control impuls of 2n S phase power cell of the 1st S phase power cell to the
1-α
2nwith basic pulse width beta
1-β
2n, α wherein
d=θ
d, β
d=π-2 θ
d, d gets 1-n; α
e=π+θ
e-n, β
e=π-2 θ
e-n, e gets n+1 to 2n; Thereby formed basic square wave control impuls P corresponding to 2n S phase power cell of the 1st S phase power cell to the
1-P
2n; Different according to controlling target, switching angle is calculated the normal methods such as equal-area method, specific subharmonic removing method of selecting and is realized.
2) pulse correction, to reduce basic square wave control impuls P
1-P
2nbetween difference in pulse width: guaranteeing under the constant prerequisite of synthetic staircase waveform output waveform, according to two principles to basic square wave control impuls P
1-P
2nstart angle α
1-α
2nwith basic pulse width beta
1-β
2nrevise, obtain optimization square-wave pulse P corresponding to 2n S phase power cell of the 1st S phase power cell to the
1'-P
2n'; Two principles are in dropping into the total equal principle of power cell of state in equal principle of square-wave pulse high level (or low level) duration that in a power frequency period, 2n S phase power cell of the 1st S phase power cell to the is corresponding and any time A phase brachium pontis, B phase brachium pontis and C phase brachium pontis;
3) to step 2) the middle optimization square-wave pulse P generating
1'-P
2n' circulate with switching cycle in the following sequence and judge anti-phase adjustment:
To optimizing square-wave pulse P
1'-P
2n' rearrange and generate the 1st combination-n and combine; The ordering of the 1st combination is P
1'-P
2n', the ordering of g combination is P
g'-P
n', P
1'-P
g-1', P
n+g'-P
2n', P
n+1'-P
n+g-1'; The ordering of n combination is P
n', P
1'-P
n-1', P
2n', P
n+1'-P
2n-1'; G is integer and meets 1 < g < n;
According to P
(g+l)' and P
(n+g+l-1)' exchange and anti-phase principle generation the 1st ' combination-n ' combination; The 1st ' ordering of combination is
the ordering of g ' combination is
the ordering of n ' combination is
l is integer and meets 0≤l≤n-1;
According to the 1st cyclic order that is incorporated into greatly the large combination of n, carry out the switching adjustment between each combination successively, and then obtain the final square wave driving pulse P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1"-P
2n"; The inner assembled arrangement order of the large combination of f is: f combination, f ' combination; F gets 1-n;
4) in module combination multi-level converter, determine the final square wave driving pulse P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1"-P
2n" after, by this final square wave driving pulse P
1"-P
2n" phase shift 2 π/3 and 4 π/3 obtain the final square wave driving pulse of all the other each power cells of two-phase respectively.
Described circulation and judge that the process of anti-phase adjustment is as follows:
Circulation is divided into two kinds of situations, the first situation refers to: at S, go up mutually each power cell of brachium pontis or S and descend mutually in the optimal control pulse cycle that each power cell inside of brachium pontis carries out, the high low logic level of respective pulses remains unchanged, when 1≤k≤n and 1≤j≤n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' and the final square wave driving pulse P of j S phase power cell afterwards that circulates
j" be consistent; When n+1≤k≤2n and n+1≤j≤2n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' and the final square wave driving pulse P of j S phase power cell afterwards that circulates
j" be consistent;
Second case refers to: at S, go up mutually each power cell of brachium pontis and S descends in the optimal control pulse cycle of carrying out between each power cell of brachium pontis mutually, the high low logic level of respective pulses is anti-phase, as 1≤k≤n and (n+1)≤and during j≤2n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' rp pulse and circulation after the final square wave driving pulse P of j S phase power cell
j" be consistent; When n+1≤k≤2n and 1≤j≤n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' rp pulse and circulation after the final square wave driving pulse P of j S phase power cell
j" be consistent;
In two kinds of situations of above-mentioned circulation, if i the optimization square-wave pulse P that S phase power cell is corresponding
i' after circulation, become m the final square wave driving pulse P that S phase power cell is corresponding
m", now, to i the optimization square-wave pulse P that S phase power cell is corresponding
i' carry out anti-phase processing, its complementary pulse
as m the final square wave driving pulse P that S phase power cell is corresponding
m"; I gets 1-n, and m gets n+1 to 2n;
In two kinds of situations of above-mentioned circulation, if t the optimization square-wave pulse P that S phase power cell is corresponding
t' after circulation, become u the final square wave driving pulse P that S phase power cell is corresponding
u", now, to t the optimization square-wave pulse P that S phase power cell is corresponding
t' carry out anti-phase processing, its complementary pulse
as u the final square wave driving pulse P that S phase power cell is corresponding
u"; U gets 1-n, and t gets n+1 to 2n.
As shown in Fig. 4 a, according to independent switch angle θ
1and θ
2determine the start angle α of the basic square wave control impuls of the 1st S phase power cell, the 2nd S phase power cell, the 3rd S phase power cell and the 4th S phase power cell
1-α
4with basic pulse width beta
1-β
4, wherein, α
1=θ
1, α
2=θ
2, α
3=π+θ
1, α
4=π+θ
2, β
1=π-2 θ
1, β
2=π-2 θ
2, β
3=π-2 θ
1, β
4=π-2 θ
2thereby, formed the 1st S phase power cell, the 2nd S phase power cell, the 3rd S phase power cell and the 4th the basic square wave control impuls P that S phase power cell is corresponding
1, P
2, P
3and P
4;
Below respectively three embodiment are described:
First embodiment:
As shown in Figure 4 b, guaranteeing under the constant prerequisite of synthetic staircase waveform output waveform, according to two principles to basic square wave control impuls P
1, P
2, P
3and P
4start angle α
1, α
2, α
3and α
4and basic pulse width beta
1, β
2, β
3and β
4revise, obtain the 1st S phase power cell, the 2nd S phase power cell, the 3rd S phase power cell and the 4th the optimization square-wave pulse P that S phase power cell is corresponding
1', P
2', P
3' and P
4'; Two principles are in dropping into the equal principle of power cell sum of state in equal principle of square-wave pulse high level (or low level) duration that the 1st S phase power cell in a power frequency period, the 2nd S phase power cell, the 3rd S phase power cell and the 4th S phase power cell are corresponding and any time A phase brachium pontis, B phase brachium pontis and C phase brachium pontis; Optimize square-wave pulse P
1', P
2', P
3' and P
4' pulse duration equate, compare the ON time of square-wave pulse with Fig. 4 a and obviously improve.Optimize square-wave pulse P
1', P
2', P
3' and P
4' start angle α
1', α
2', α
3' and α
4' satisfied following formula: α
1'=α
1-2 θ
1, α
2'=α
2, α
3'=α
3-2 θ
1, α
4'=α
4; Optimize square-wave pulse P
1', P
2', P
3' and P
4' basic pulse width beta
1, β
2, β
3and β
4be π+θ
1-θ
2;
As Fig. 4 c is depicted as three level MMC square-wave pulse cyclic sequence P under 4 times of power frequency cycle frequencys
1", P
2", P
3" and P
4"; In this embodiment to optimizing square-wave pulse P
1', P
2', P
3' and P
4' carry out following operation: according to P
1' and P
4' exchange and anti-phase, P
2' and P
3' exchange and anti-phase principle generate the 2nd combination (
with
), according to P
1' and P
2' exchange, P
3' and P
4' principle of exchanging generates the 3rd combination (P
2', P
1', P
4' and P
3'), according to P
1' and P
3' exchange and anti-phase, P
2' and P
4' exchange and anti-phase principle generate the 4th combination (
with
), successively according to the 1st combination (P
1', P
2', P
3' and P
4'), the 2nd combination (
with
), the 3rd combination (P
2', P
1', P
4' and P
3') and the 4th combination (
with
) order with the frequency of 6 times of power frequencies to the optimization square-wave pulse P in Fig. 4 b
1', P
2', P
3' and P
4' adjustment that circulates, obtained the 1st S phase power cell, the 2nd S phase power cell, the 3rd S phase power cell and the 4th the square-wave pulse cyclic sequence P that S phase power cell is corresponding
1", P
2", P
3" and P
4".
Second embodiment:
As shown in Figure 5 a, guaranteeing under the constant prerequisite of synthetic staircase waveform output waveform, according to two principles to basic square wave control impuls P
1, P
2, P
3and P
4start angle α
1, α
2, α
3and α
4and basic pulse width beta
1, β
2, β
3and β
4revise, obtain the 1st S phase power cell, the 2nd S phase power cell, the 3rd S phase power cell and the 4th the optimization square-wave pulse P that S phase power cell is corresponding
1', P
2', P
3' and P
4'; Two principles are in dropping into the equal principle of power cell sum of state in equal principle of square-wave pulse high level (or low level) duration that the 1st S phase power cell in a power frequency period, the 2nd S phase power cell, the 3rd S phase power cell and the 4th S phase power cell are corresponding and any time A phase brachium pontis, B phase brachium pontis and C phase brachium pontis; Optimize square-wave pulse P
1', P
2', P
3' and P
4' pulse duration equate, compare the ON time of square-wave pulse with Fig. 4 a and obviously improve.Optimize square-wave pulse P
1', P
2', P
3' and P
4' start angle α
1', α
2', α
3' and α
4' satisfied following formula: α
1'=α
1, α
2'=α
2, α
3'=α
3-θ
1-θ
2, α
4'=α
4-θ
1-θ
2; Optimize square-wave pulse P
1', P
2', P
3' and P
4' basic pulse width beta
1, β
2, β
3and β
4be π;
As shown in Figure 5 b, in this embodiment to optimizing square-wave pulse P
1', P
2', P
3' and P
4' carry out following operation: according to P
1' and P
4' exchange and anti-phase, P
2' and P
3' exchange and anti-phase principle generate the 2nd combination (
with
), according to P
1' and P
2' exchange, P
3' and P
4' principle of exchanging generates the 3rd combination (P
2', P
1', P
4' and P
3'), according to P
1' and P
3' exchange and anti-phase, P
2' and P
4' exchange and anti-phase principle generate the 4th combination (
with
), successively according to the 1st combination (P
1', P
2', P
3' and P
4'), the 2nd combination (
with
), the 3rd combination (P
2', P
1', P
4' and P
3') and the 4th combination (
with
) order with the frequency of 6 times of power frequencies to the optimization square-wave pulse P in Fig. 4 b
1', P
2', P
3' and P
4' adjustment that circulates, obtained the 1st S phase power cell, the 2nd S phase power cell, the 3rd S phase power cell and the 4th the square-wave pulse cyclic sequence P that S phase power cell is corresponding
1", P
2", P
3" and P
4".
The 3rd embodiment:
In step 1) obtain the basic square wave control impuls P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1-P
2nafterwards, with basic square wave control impuls P
1-P
2nstep of replacing 3) the optimization square-wave pulse P in
1'-P
2n', then perform step 3), can obtain final square wave driving pulse P
1"-P
2n".Below corresponding embodiment:
As shown in Figure 6, in this embodiment, skips steps 2), directly adopt step 1) in basic square wave control impuls P
1, P
2, P
3and P
4generate the 1st combination (P
1, P
2, P
3and P
4), and according to P
1and P
4exchange and anti-phase, P
2and P
3exchange and anti-phase principle generate the 2nd combination (
with
), according to P
1and P
2exchange, P
3and P
4the principle of exchanging generates the 3rd combination (P
2, P
1, P
4and P
3), according to P
1and P
3exchange and anti-phase, P
2and P
4exchange and anti-phase principle generate the 4th combination (
with
), successively according to the order of the 1st combination, the 2nd combination, the 3rd combination and the 4th combination with the frequency of 6 times of power frequencies to the basic square wave control impuls P in Fig. 4 a
1, P
2, P
3and P
4the adjustment that circulates, has obtained the 1st S phase power cell, the 2nd S phase power cell, the 3rd S phase power cell and the 4th the square-wave pulse cyclic sequence P that S phase power cell is corresponding
1", P
2", P
3" and P
4".
Being the interchange output phase voltage experimental waveform of three level MMC under first embodiment as shown in Figure 7a, is the 1st S phase power cell of three level MMC and the 2nd the DC capacitor voltage V that S phase power cell is corresponding under the first implementation as shown in Figure 7b
c1, V
c2experimental waveform, it is 18 frequencys multiplication that circulation is adjusted frequency; Being the interchange output phase voltage experimental waveform of three level MMC under second embodiment as shown in Figure 8 a, is the 2nd S phase power cell of three level MMC and the 4th the DC capacitor voltage V that S phase power cell is corresponding under second embodiment as shown in Figure 8 b
c2, V
c4experimental waveform, it is 10 frequencys multiplication that circulation is adjusted frequency; Experimental result shows without any capacitance voltage control measure, the square-wave pulse circulation modulating method of this module combination multi-level converter has been realized the meritorious mean allocation of energy and the equilibrium of DC capacitor voltage control effect between each power cell of MMC, and export phase voltage is typical three level staircase waveform waveforms simultaneously.
The above; be only the present invention's embodiment preferably, but protection scope of the present invention is not limited to this, is anyly familiar with in technical scope that those skilled in the art disclose in the present invention; the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.
Claims (4)
1. a square-wave pulse circulation modulating method for module combination multi-level converter, is characterized in that, comprises the following steps:
1) setting module combination multi-level converter contains 2n A phase power cell, a 2n B phase power cell and 2n C phase power cell, 2n the A phase power cell of 2n A phase power cell formation of n+1 A phase power cell to that is positioned at n A phase power cell of the 1st A phase power cell to the of brachium pontis and is positioned at lower brachium pontis, 2n the B phase power cell of 2n B phase power cell formation of n+1 B phase power cell to that is positioned at n B phase power cell of the 1st B phase power cell to the of brachium pontis and is positioned at lower brachium pontis, 2n the C phase power cell of 2n C phase power cell formation of n+1 C phase power cell to that is positioned at n C phase power cell of the 1st C phase power cell to the of brachium pontis and is positioned at lower brachium pontis, n is more than or equal to 1 positive integer,
S is A phase, B phase or C phase mutually, for 2n S phase power cell, and execution step 1) to step 3);
Carry out the calculating of square-wave pulse switching angle, form basic square-wave pulse: first according to the output level of module combination multi-level converter, count n+1, in calculating, in brachium pontis, for the synthesis of interchange, export the switching angle θ of staircase voltage
1-θ
n, to determine the start angle α of the basic square wave control impuls of 2n S phase power cell of the 1st S phase power cell to the
1-α
2nwith basic pulse width beta
1-β
2n, α wherein
d=θ
d, β
d=π-2 θ
d, d gets 1-n; α
e=π+θ
e-n, β
e=π-2 θ
e-n, e gets n+1 to 2n; Thereby formed basic square wave control impuls P corresponding to 2n S phase power cell of the 1st S phase power cell to the
1-P
2n;
2) pulse correction, to reduce basic square wave control impuls P
1-P
2nbetween difference in pulse width: guaranteeing under the constant prerequisite of synthetic staircase waveform output waveform, according to two principles to basic square wave control impuls P
1-P
2nstart angle α
1-α
2nwith basic pulse width beta
1-β
2nrevise, obtain optimization square-wave pulse P corresponding to 2n S phase power cell of the 1st S phase power cell to the
1'-P
2n'; Two principles are in dropping into the total equal principle of power cell of state in principle that square-wave pulse high level lasting time that in a power frequency period, 2n S phase power cell of the 1st S phase power cell to the is corresponding is equal and any time A phase brachium pontis, B phase brachium pontis and C phase brachium pontis;
3) to step 2) the middle optimization square-wave pulse P generating
1'-P
2n' circulate with switching cycle in the following sequence and judge anti-phase adjustment:
To optimizing square-wave pulse P
1'-P
2n' rearrange and generate the 1st combination-n and combine; The ordering of the 1st combination is P
1'-P
2n', the ordering of g combination is P
g'-P
n', P
1'-P
g-1, P
n+g'-P
2n', P
n+1'-P
n+g-1'; The ordering of n combination is P
n', P
1'-P
n-1, P
2n', P
n+1'-P
2n-1'; G is integer and meets 1 < g < n;
According to
with
exchange and anti-phase principle generation the 1st ' combination-n ' combination; The 1st ' ordering of combination is
the ordering of g ' combination is
the ordering of n ' combination is
for integer and satisfied
According to the 1st cyclic order that is incorporated into greatly the large combination of n, carry out the switching adjustment between each combination successively, and then obtain the final square wave driving pulse P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1"-P
2n"; The inner assembled arrangement order of the large combination of f is: f combination, f ' combination; F gets 1-n;
4) in module combination multi-level converter, determine the final square wave driving pulse P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1"-P
2n" after, by this final square wave driving pulse P
1"-P
2n" phase shift 2 π/3 and 4 π/3 obtain the final square wave driving pulse of all the other each power cells of two-phase respectively.
2. the square-wave pulse circulation modulating method of a kind of module combination multi-level converter according to claim 1, is characterized in that, described circulation and judge that the process of anti-phase adjustment is as follows:
Circulation is divided into two kinds of situations, the first situation refers to: at S, go up mutually each power cell of brachium pontis or S and descend mutually in the optimal control pulse cycle that each power cell inside of brachium pontis carries out, the high low logic level of respective pulses remains unchanged, when 1≤k≤n and 1≤j≤n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' and the final square wave driving pulse P of j S phase power cell afterwards that circulates
j" be consistent; When n+1≤k≤2n and n+1≤j≤2n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' and the final square wave driving pulse P of j S phase power cell afterwards that circulates
j" be consistent;
Second case refers to: at S, go up mutually each power cell of brachium pontis and S descends in the optimal control pulse cycle of carrying out between each power cell of brachium pontis mutually, the high low logic level of respective pulses is anti-phase, as 1≤k≤n and (n+1)≤and during j≤2n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' rp pulse and circulation after the final square wave driving pulse P of j S phase power cell
j" be consistent; When n+1≤k≤2n and 1≤j≤n, the optimization square-wave pulse P of front k the S phase power cell that circulate
k' rp pulse and circulation after the final square wave driving pulse P of j S phase power cell
j" be consistent;
In two kinds of situations of above-mentioned circulation, if i the optimization square-wave pulse P that S phase power cell is corresponding
i' after circulation, become m the final square wave driving pulse P that S phase power cell is corresponding
m", now, to i the optimization square-wave pulse P that S phase power cell is corresponding
i' carry out anti-phase processing, its complementary pulse
as m the final square wave driving pulse P that S phase power cell is corresponding
m"; I gets 1-n, and m gets n+1 to 2n;
In two kinds of situations of above-mentioned circulation, if t the optimization square-wave pulse P that S phase power cell is corresponding
t' after circulation, become u the final square wave driving pulse P that S phase power cell is corresponding
u", now, to t the optimization square-wave pulse P that S phase power cell is corresponding
t' carry out anti-phase processing, its complementary pulse
as u the final square wave driving pulse P that S phase power cell is corresponding
u"; U gets 1-n, and t gets n+1 to 2n.
3. the square-wave pulse circulation modulating method of a kind of module combination multi-level converter according to claim 1, is characterized in that, the method that described square-wave pulse switching angle is calculated is equal-area method, specific subharmonic removing method.
4. the square-wave pulse circulation modulating method of a kind of module combination multi-level converter according to claim 1, is characterized in that, in step 1) obtain the basic square wave control impuls P that 2n S phase power cell of the 1st S phase power cell to the is corresponding
1-P
2nafterwards, with basic square wave control impuls P
1-P
2nstep of replacing 3) the optimization square-wave pulse P in
1'-P
2n', then perform step 3), can obtain final square wave driving pulse P
1"-P
2n".
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| CN102843018B (en) * | 2012-08-09 | 2014-12-03 | 东南大学 | Integral-variable bicirculating mapping pulse width modulation method of modularized multi-level converter |
| CN103199729B (en) * | 2013-04-10 | 2016-01-20 | 国家电网公司 | A kind of modular multi-level converter submodule grouping Staircase wave method |
| CN103390916B (en) * | 2013-07-12 | 2016-07-06 | 上海交通大学 | Energy storage chain type power conversion system Staircase wave is interior SOC balance method mutually |
| CN103560689B (en) * | 2013-10-31 | 2017-01-18 | 辽宁工程技术大学 | Method for achieving fault-tolerant control of medium-voltage cascading STATCOM through redundancy voltage vectors |
| CN106357140B (en) * | 2016-08-29 | 2018-10-23 | 华东交通大学 | A kind of same phase laminated type SPWM pulse allocating methods applied to cascaded multilevel inverter |
| CN107733269B (en) * | 2017-10-12 | 2019-08-02 | 合肥工业大学 | Expand the square-wave compensation control method of Cascade H bridge type photovoltaic DC-to-AC converter range of operation |
| CN108880306B (en) * | 2018-07-03 | 2020-01-31 | 南方电网科学研究院有限责任公司 | MMC topological structure and control method |
| CN109889052B (en) * | 2019-01-31 | 2020-08-18 | 南方电网科学研究院有限责任公司 | Method and device for controlling capacitor voltage of modular multilevel matrix converter |
| CN115208226B (en) * | 2022-09-19 | 2022-12-06 | 湖南大学 | Modular cascade power amplifier switch combination alternate multilevel modulation method |
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