CN105703650B - A kind of more T-shaped three-level inverter control method for parallel using SHEPWM - Google Patents
A kind of more T-shaped three-level inverter control method for parallel using SHEPWM Download PDFInfo
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- CN105703650B CN105703650B CN201610166225.3A CN201610166225A CN105703650B CN 105703650 B CN105703650 B CN 105703650B CN 201610166225 A CN201610166225 A CN 201610166225A CN 105703650 B CN105703650 B CN 105703650B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
- H02M7/487—Neutral point clamped inverters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
- H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0038—Circuits or arrangements for suppressing, e.g. by masking incorrect turn-on or turn-off signals, e.g. due to current spikes in current mode control
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- Power Engineering (AREA)
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Abstract
The invention discloses a kind of more T-shaped three-level inverter control method for parallel using SHEPWM, comprise the following steps：The number of the overtone order eliminated as needed determines the switching angle number in each cycle；The switch angle of selective harmonic elimination pulsewidth modulation is solved based on multi-objective particle swarm optimization method, generates corresponding selective harmonic elimination pulsewidth modulation signal；Gather the mid-point voltage and zero sequence circulation of T-shaped three-level inverter parallel system；Sequential is set, small vector control is carried out to selective harmonic elimination pulsewidth modulation signal according to mid-point voltage or zero sequence circulation according to setting sequential, selective harmonic elimination pulsewidth modulation signal is rewritten.The present invention is controlled according to the sequential alignment voltage or zero sequence circulation that set.Because more inverter midpoints are connected, as long as so a certain moment controls the mid-point voltage of wherein any one inverter, system mid-point voltage just balances.
Description
Technical field
The present invention relates to a kind of more T-shaped three-level inverter control method for parallel using SHEPWM.
Background technology
Low-voltage network is accessed on a large scale along with the distributed energy including photovoltaic generating system, and power network is to parallel network reverse
Device output current wave quality proposes higher requirement, and traditional two level grid-connected inverters are difficult to meet the high quality of power supply of bulk power grid
It is required that.The appearance of T-shaped three level grid-connected inverter solves above mentioned problem, as shown in Fig. 2 being compared with traditional two level, this is inverse
Becoming utensil has the advantages that harmonic wave is small, switching loss is low, electromagnetic interference is small；With conventional diode clamper type three-level inverter phase
Have the advantages that to have less number of switches than, the inverter, conduction loss is small and power attenuation is uniform；And T-shaped three-level inverter is opened
Close frequency efficiency highest between 4kHz to 30kHz.Therefore T-shaped three-level inverter has been widely applied to photovoltaic generation and micro-
Power network distributed generating occasion, but capacity is always to restrict its fast-developing bottleneck.
The parallel connection of T-shaped three level grid-connected inverter of multimachine can increase power system capacity, reliability and efficiency, have become big
The important selection that power distribution formula generates electricity, but hardware mismatches between module, dead time and control algolithm perform the time
Circulation can be produced etc. difference.Circulation can increase system loss and cause grid-connected current to distort, and have a strong impact on the longevity of IGBT switching tubes
Life, therefore the loop current suppression for studying T-shaped three-level inverter in parallel is significant.
Modulated compared to sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM), particular harmonic null method
(SHEPWM) have switching frequency is low, switching loss is small, output voltage quality is good and the series of advantages such as small is lost, suitable for big
Power occasion, it is the modulator approach for being often used in eliminating low-order harmonic in a kind of field of power electronics.
The content of the invention
The present invention is in order to solve the above problems, it is proposed that a kind of more T-shaped three-level inverters using SHEPWM are in parallel
Control method, the present invention is studied the key technology of three-level inverter parallel system, for inverter direct-flow side
Neutral point voltage balance problem carries out detailed analysis, the advantages of for SHEPWM and T-shaped three-level inverter parallel connection, proposes a kind of
Suitable for the new SHEPWM methods of more T-shaped three-level inverter parallel systems.System is by traditional SHEPWM correlation formulas meter
Switch angle is calculated, a small vector replacement system is then added after conventional three-phase SHEPWM modulation.In parallel system
Inverter is controlled according to the sequential alignment voltage or zero sequence circulation set.Because more inverter midpoints are connected, institute
As long as controlling the mid-point voltage of wherein any one inverter with a certain moment, system mid-point voltage just balances.Now remaining
Inverter calculates zero sequence circulation by measuring output current and is controlled by.The method proposed does not influence inverter output
Line voltage waveform, so with the function with traditional SHEPWM identicals elimination low-order harmonic, and can effectively suppress circulation, energy
Make T-shaped three-level inverter parallel system stable and high effective operation.
To achieve these goals, the present invention adopts the following technical scheme that：
A kind of more T-shaped three-level inverter control method for parallel using SHEPWM, comprise the following steps：
(1) number of the overtone order eliminated as needed determines the switching angle number in each cycle；
(2) the switch angle of selective harmonic elimination pulsewidth modulation is solved based on multi-objective particle swarm optimization method, generates phase
The selective harmonic elimination pulsewidth modulation signal answered；
(3) mid-point voltage and zero sequence circulation of T-shaped three-level inverter parallel system are gathered；
(4) sequential is set, according to setting sequential according to mid-point voltage or zero sequence circulation to selective harmonic elimination pulsewidth modulation
Signal carries out small vector control, and selective harmonic elimination pulsewidth modulation signal is rewritten.
In the step (1), the switching angle number in the per quart cycle adds 1 for the overtone order that needs eliminate.
If eliminating N-1 specific harmonic components, N number of switching angle is set, just can form N number of independent side
Journey, so as to which the N-1 harmonic component for wishing to eliminate while fundamental voltage amplitude is selected, can also be eliminated.
In the step (2), arteries and veins is eliminated using the level particular harmonic of multi-objective particle swarm optimization (MOPSO) Algorithm for Solving three
Wide modulation switch angle.
In the step (4), the parallel system cycle is set as T, and when n platform inverter parallels, parallel system is each
In cycle T：I-th inverter is responsible for control mid-point voltage within (i-1) T/n~iT/n periods, is responsible for control in other periods
Zero sequence circulation processed.
In the step (4), control mid-point voltage when, if the mid-point voltage of T-shaped three-level inverter in threshold range,
Do not change T-shaped three-level inverter then, it is directly entered three-level inverter, on off state is otherwise revised as small vector letter
Number, selective harmonic elimination pulsewidth modulation signal is rewritten.
Further, in the step (4), when the absolute value of mid-point voltage is more than mid-point voltage threshold value, if mid-point voltage
More than zero, on off state is changed to N-type small vector；If mid-point voltage is less than zero, on off state is changed to p-type small vector,
When the absolute value of mid-point voltage is less than mid-point voltage threshold value, on off state does not change.
In the step (4), when controlling zero sequence circulation, if zero sequence circulation exceedes threshold range, if zero sequence circulation is more than zero,
On off state is changed to N-type small vector, if zero sequence circulation is less than zero, on off state is changed to p-type small vector, if zero sequence ring
In threshold range, on off state does not change stream.
A kind of more T-shaped three-level inverter control method for parallel using SHEPWM, including particular harmonic eliminate pulsewidth
Modulation signal generator, small vector controller, switches set, PWM signal generator and T-shaped three-level inverter parallel system, its
In, T-shaped three-level inverter parallel system, including multiple T-shaped three-level inverters, all T-shaped three-level inverters, which share, to be handed over
Dc bus, it is connected in parallel to each other；
The selective harmonic elimination pulsewidth modulation signal generator exports selective harmonic elimination pulsewidth modulation signal to switch
Group, the small vector controller gathers the mid-point voltage and zero sequence circulation of T-shaped three-level inverter parallel system, according to setting
Sequential, respectively alignment voltage and zero sequence circulation be controlled, judge it whether in respective given threshold；According to midpoint electricity
The size of pressure and zero sequence circulation, is confirmed whether to rewrite selective harmonic elimination pulsewidth modulation signal, is occurred by pwm signal
Device generates control signal, controls the switching device of T-shaped three-level inverter parallel system.
Further, the small vector controller is judged according to mid-point voltage, if mid-point voltage is in given threshold model
In enclosing, then do not change the state of switches set, selective harmonic elimination pulsewidth modulation signal is generated by PWM signal generator and control
Signal, control the switching device of T-shaped three-level inverter parallel system；
If mid-point voltage, not in the range of given threshold, small vector controller changes switches set state, particular harmonic is disappeared
Except pulse-width signal is changed as small voltage vector, control signal is generated by PWM signal generator, controls T-shaped three level
The switching device of inverter parallel system.
The one of voltage difference of the mid-point voltage between two shunt capacitances of DC side of T-shaped three-level inverter
Half.
When the absolute value of the mid-point voltage is more than mid-point voltage threshold value, if mid-point voltage is more than zero, on off state is changed
It is changed into N-type small vector；If mid-point voltage is less than zero, on off state is changed to p-type small vector.
When the small vector controller controls according to zero sequence circulation, if zero sequence circulation exceedes threshold range, if zero sequence circulation
More than zero, on off state is changed to N-type small vector, if zero sequence circulation is less than zero, on off state is changed to p-type small vector,
In threshold range, if on off state does not change zero sequence circulation.
Beneficial effects of the present invention are：
(1) mid-point voltage can be limited to a smaller surge area, midpoint by SHEPWM control modes in the present invention
It is set to restore balance rapidly during voltage deviation equalization point, and the ability that traditional SHEPWM eliminates to particular harmonic is essentially identical.
(2) possesses three-level topology harmonic content using SHEPWM T-shaped three-level inverter parallel system in the present invention
Small, the advantages of system effectiveness is high, the advantage that parallel system maintainability is good, redundancy is high, is easy to dilatation is also had concurrently.
(3) solve loop current suppression well using SHEPWM T-shaped three-level inverter parallel system in the present invention to ask
Topic and neutral point voltage balance problem.
Brief description of the drawings
Fig. 1 is more three-level inverter parallel system topological diagrams；
Fig. 2 is three-level inverter topology figure；
Fig. 3 is three-level inverter SHEPWM typical waveform；
Fig. 4 is the influence schematic diagram of small vector alignment voltage；
Fig. 5 (a) is that big voltage vector [PPN] influences schematic diagram to three-level inverter mid-point voltage,
Fig. 5 (b) is that middle voltage vector [PON] influences schematic diagram to three-level inverter mid-point voltage；
Fig. 5 (c) is that Zero voltage vector [PPP] influences schematic diagram to three-level inverter mid-point voltage；
Fig. 5 (d) is that p-type small voltage vector [POO] influences schematic diagram to three-level inverter mid-point voltage；
Fig. 5 (e)) it is that N-type small voltage vector [ONN] influences schematic diagram to three-level inverter mid-point voltage；
Fig. 6 by proposition particular harmonic null method mid-point voltage in T-shaped three-level inverter control principle；
Fig. 7 by proposition particular harmonic null method mid-point voltage in T-shaped three-level inverter control flow chart；
Fig. 8 by proposition particular harmonic null method zero-sequence current in T-shaped three-level inverter control principle；
Fig. 9 by proposition particular harmonic null method zero-sequence current in T-shaped three-level inverter control flow chart；
Figure 10 is three inverter parallel system voltage on line side and output current；
Figure 11 (a) is the simulation result of First inverter；
Figure 11 (b) is the simulation result of second inverter；
Figure 11 (c) is the simulation result of the 3rd inverter；
Figure 12 is the frequency analysis of inverter output voltage simulation result；
Figure 13 (a) is the simulation result of First inverter, and wherein solid line represents upside capacitance voltage value, under dotted line represents
Lateral capacitance magnitude of voltage (similarly hereinafter)；
Figure 13 (b) is the simulation result of second inverter；
Figure 13 (c) is the simulation result of the 3rd inverter；
Figure 14 is the simulation result of the respective zero-sequence current of three inverters.
Embodiment：
The invention will be further described with embodiment below in conjunction with the accompanying drawings.
As shown in figure 1, three-level inverter parallel system topological diagram is as shown in figure 1, more inverters share alternating current-direct current mother
Line, P, N are the positive and negative busbar of parallel system；A, B, C are the three-phase grid point of parallel system；Aj, bj, cj are inverter output
Exchange end, Cj1、Cj2For two electric capacity with DC side parallel, midpoint Zj, system uses L wave filters, filter inductance Li, zero
Sequence electric current is izj, imjFor the m phase output currents of jth platform inverter, m=a, b, c, j=1,2,；iA、iB、iCFor system grid connection electricity
Stream.
Control strategy for inverter is illustrated with single inverter structure as shown in Figure 2.Two electric capacity C of DC side series connection1And C2,
Midpoint Z is produced, so that the switch of the upper device of inverter and lower device will produce positive level and negative level.a、b、c
Three-phase respectively connects four switching devices for carrying anti-paralleled diode, passes through LA、LB、LCPowered to threephase load.Each half-bridge
Inverter has three kinds of states：Upper arm switch device conductive, underarm switch device conductive, auxiliary switch break-over of device, are exported respectively
Positive level, negative level, zero level.A kind of more T-shaped three-level inverter control method for parallel using SHEPWM in the present invention
Mainly include the following steps that：
(1) the switching angle number in the per quart cycle is determined according to the number for eliminating overtone order；
(2) switch angle is calculated according to traditional SHEPWM principles；
(3) a small vector control system is increased after conventional three-phase SHEPWM modulation to control mid-point voltage and ring
Stream；
(4) more inverters share alternating current-direct current bus, realize parallel running.
(5) inverter is controlled according to the sequential alignment voltage or zero sequence circulation set in parallel system.
In step (1), if to eliminate N-1 specific harmonic components, N number of switching angle is set, can just be formed N number of
Independent equation, so as to which the N-1 harmonic component for wishing to eliminate while fundamental voltage amplitude is selected, can also be eliminated.
In step (2), using the level SHEPWM switching angles of multi-objective particle swarm optimization (MOPSO) Algorithm for Solving three.
In step (3), SHEPWM switching signals are produced by traditional SHEPWM signal generators, are increased small vector thereafter and are replaced
Device.When small voltage vector switch state occurs, small voltage vector replacement system is replaced by detecting mid-point voltage and Direction of circulation
Change small vector；When small voltage vector switch state does not occur, small vector replacement system does not change on off state.
In step (4), more inverters share alternating current-direct current bus, realize parallel running.
In the step (5), the parallel system cycle is set as T=0.02s.When n platform inverter parallels, taken in conjunction
Unite in each cycle T：I-th inverter is responsible for control mid-point voltage V within (i-1) T/n~iT/n periodsZi, at other
Section is responsible for control zero sequence circulation iZi。
It is responsible for the control strategy for inverter of control zero sequence circulation：iZMore than set circulation threshold values IrangeWhen, if iZ>0,
On off state is changed to N-type small vector, if iZ<0, on off state is changed to p-type small vector.When | iZ|<Irange, switch shape
State does not change.
It is responsible for the control strategy for inverter of control mid-point voltage：When | VZ2|>VrangeWhen, if VZ2>0, on off state is changed
For N-type small vector；If VZ2<0, on off state is changed to p-type small vector.When | VZ2|<Vrange, on off state do not change.
Traditional SHEPWM modulator approaches is calculate N number of switching angle in the per quart cycle, to solve N number of switching angle,
Need to form N number of equation, wherein N-1 equation eliminates low-order harmonic, and an equation determines modulation ratio M.A kind of typical three electricity
As shown in figure 3, wherein Vxz is single-phase output voltage, its Fourier space is flat SHEPWM waveforms
Wherein x=a, b, c；Bn is fourier coefficient；Bn is given by
Wherein n=1,5,7,3N-2.
By following cost function, to choose equation optimal solution
Wherein M is modulation index.On off state can be expressed as space voltage vector, according to the size of space voltage vector
Zero vector, small vector, big vector, middle vector can be classified as, small voltage vector can be divided into p-type vector N-type vector again, such as
Shown in Fig. 4 and table 1.
Table 1
Using SHEPWM inverter mid-point voltage VZIt is expressed as
Wherein VC1And VC2It is DC bus capacitor C1And C2Magnitude of voltage.Influence such as Fig. 5 institutes of on off state alignment voltage
Show：Big vector zero vector alignment voltage does not influence because in this case midpoint Z without and DC side it is positive and negative
Extremely it is connected, because two electric capacity do not have discharge and recharge, two capacitance voltages do not change, and mid-point voltage does not also change, such as Fig. 5
(a), shown in (c)；Fig. 5 (b) shows the design sketch of middle vector, and now midpoint is connected with the positive minus side of DC side, midpoint electricity
The situation of change of pressure thus when midpoint electric current determine；When inverter selects p-type small vector on off state, load is connected on midpoint
With the positive pole of DC side, electric capacity C1Electric discharge, electric current flow into midpoint, and mid-point voltage rises, as shown in Fig. 5 (d)；In contrast, N-type
Small vector can decline mid-point voltage, as shown in Fig. 5 (e).
I-th inverter zero-sequence current iziFor：
izi=iai+ibi+ici (5)
Wherein i is the device numbering of inverter.The zero sequence circulation and output filter inductance L of T-shaped three-level inverter, in
Point current potential is relevant with off state, for the T-shaped three-level inverter parallel system of n platforms, the zero sequence circulation of i-th inverter output
iziFor：
In view of some inverter regulation mid-point voltages may conflict with suppressing circulation, therefore to inverter in parallel system
Sequential is set, each inverter is controlled according to the sequential alignment voltage or zero sequence circulation set when system works.This
The parallel system cycle is set in invention as T=0.02s, when n platform inverter parallels, in each cycle T of parallel system：The
I platforms inverter is responsible for control mid-point voltage V within (i-1) T/n~iT/n periodsZi, it is responsible for controlling zero sequence ring in other periods
Flow iZi。
Neutral point voltage balance, control original are kept by replacing small voltage vector using SHEPWM inverter in the present invention
Reason is as shown in Figure 6.SHEPWM switching signals are produced by traditional SHEPWM systems, the small electricity when small voltage vector switch state occurs
Press vector controller effect；When small voltage vector switch state does not occur, small vector controller is blocked, and on off state is not
Become.
The flow chart of neutral-point voltage balance is provided by Fig. 7 in the present invention, wherein VrangeIt is the restriction ripple of mid-point voltage
Dynamic amplitude, VZIt is mid-point voltage, the working condition of small vector controller is as follows：
State one：|VZ|>Vrange, small vector is replaced under this state.
a)VZ>0：According to table 2, on off state is changed to N-type small vector.
b)VZ<0：According to table 2, on off state is changed to p-type small vector.
State two：|VZ|<Vrange, on off state do not change.
Neutral point voltage balance is kept by replacing small voltage vector, control principle is as shown in Figure 8 in the present invention.Inverter
Switching signal produced by traditional SHEPWM systems, when small vector on off state occurs small voltage vector controller act on；When
When small voltage vector switch state does not occur, small vector controller is blocked, and on off state is constant.
The flow chart that zero-sequence current controls in the present invention is provided by Fig. 9, wherein IrangeIt is the restriction fluctuation width of zero-sequence current
Degree, iZIt is zero-sequence current, the working condition of small vector controller is as follows：
State one：|iZ|>Irange, small vector is replaced under this state.
a)iZ>0：According to table 2, on off state is changed to N-type small vector.
b)iZ<0：According to table 2, on off state is changed to p-type small vector.
State two：|iZ|<Irange, on off state do not change.
Simulation study
A kind of more T-shaped three-level inverter control method for parallel for using SHEPWM proposed in the present invention can be with bright
Reduce the concussion scope of DC side mid-point voltage aobviously, it is excellent not only to possess that three-level topology harmonic content is small, system effectiveness is high
Point, the advantage that parallel system maintainability is good, redundancy is high, is easy to dilatation is also had concurrently, has solved loop current suppression well and ask
Topic and neutral point voltage balance problem.
In MATLAB/simulink 2012B, with more three-level inverter parallel system topological structures shown in Fig. 1
Simulation study is carried out to control strategy proposed by the present invention, selectes n=3.To three inverters give electric current be respectively 15A,
15A, 25A, simulation result is as shown in FIG. 10 to 14.Know that parallel system to the amplitude of power network output current is 55A, is from Fig. 8
Three inverter output current sums.Fig. 9 is the inverter output voltage waveform using SHEPWM, from the humorous of voltage shown in Figure 10
Wave analysis is understood, specified low-order harmonic is eliminated by SHEPWM.Because two inverters share alternating current-direct current bus and midpoint
It is connected with each other, the DC side midpoint potential of two inverters is equal, as shown in Figure 11 (a)-Figure 11 (c), DC side two up and down
The magnitude of voltage of electric capacity is 100V, and mid-point voltage is limited in the fluctuation range of a very little.Meanwhile as shown in Figure 12, two
Circulation between inverter is limited to 0A, and circulation is effectively suppressed.
By above simulation result, a kind of more T-shaped three-level inverters using SHEPWM are in parallel in the present invention
Mid-point voltage and zero sequence circulation can be limited to the surge area of a very little by control method, and keep traditional SHEPWM to disappear
Except the ability of particular harmonic, solve the problems, such as loop current suppression and neutral point voltage balance problem well.
Although above-mentioned the embodiment of the present invention is described with reference to accompanying drawing, model not is protected to the present invention
The limitation enclosed, one of ordinary skill in the art should be understood that on the basis of technical scheme those skilled in the art are not
Need to pay various modifications or deformation that creative work can make still within protection scope of the present invention.
Claims (5)
1. a kind of more T-shaped three-level inverter control method for parallel using SHEPWM, it is characterized in that：Comprise the following steps：
(1) number of the overtone order eliminated as needed determines the switching angle number in each cycle；
(2) the switch angle of selective harmonic elimination pulsewidth modulation is solved based on multi-objective particle swarm optimization method, generation is corresponding
Selective harmonic elimination pulsewidth modulation signal；
(3) mid-point voltage and zero sequence circulation of T-shaped three-level inverter parallel system are gathered；
(4) sequential is set, according to setting sequential according to mid-point voltage or zero sequence circulation to selective harmonic elimination pulsewidth modulation signal
Small vector control is carried out, selective harmonic elimination pulsewidth modulation signal is rewritten；
In the step (4), control mid-point voltage when, if the mid-point voltage of T-shaped three-level inverter in threshold range, no
Change T-shaped three-level inverter, it is directly entered three-level inverter, on off state is otherwise revised as small vector signal,
Selective harmonic elimination pulsewidth modulation signal is rewritten；
In the step (4), when the absolute value of mid-point voltage is more than mid-point voltage threshold value, if mid-point voltage is more than zero, shape is switched
State is changed to N-type small vector；If mid-point voltage is less than zero, on off state is changed to p-type small vector, exhausted when mid-point voltage
When being less than mid-point voltage threshold value to value, on off state does not change；
In the step (4), when controlling zero sequence circulation, if zero sequence circulation exceedes threshold range, if zero sequence circulation is more than zero, switch
State is changed to N-type small vector, if zero sequence circulation is less than zero, on off state is changed to p-type small vector, if zero sequence circulation exists
In threshold range, on off state does not change.
2. a kind of more T-shaped three-level inverter control method for parallel using SHEPWM as claimed in claim 1, its feature
It is：In the step (1), the switching angle number in the per quart cycle adds 1 for the overtone order that needs eliminate.
3. a kind of more T-shaped three-level inverter control method for parallel using SHEPWM as claimed in claim 1, its feature
It is：In the step (4), the parallel system cycle is set as T, when n platform inverter parallels, each cycle T of parallel system
It is interior：I-th inverter is responsible for control mid-point voltage within (i-1) T/n~iT/n periods, is responsible for controlling zero sequence in other periods
Circulation.
4. a kind of more T-shaped three-level inverter control method for parallel using SHEPWM, it is characterized in that：Disappear including particular harmonic
Except pulse-duration modulation signal generator, small vector controller, switches set, PWM signal generator and T-shaped three-level inverter taken in conjunction
System, wherein, T-shaped three-level inverter parallel system, including multiple T-shaped three-level inverters, all T-shaped three-level inverters are total to
With alternating current-direct current bus, it is connected in parallel to each other；
The selective harmonic elimination pulsewidth modulation signal generator exports selective harmonic elimination pulsewidth modulation signal to switches set, institute
Mid-point voltage and zero sequence circulation that small vector controller gathers T-shaped three-level inverter parallel system are stated, according to the sequential of setting,
Whether alignment voltage and zero sequence circulation are controlled respectively, judge it in respective given threshold；According to mid-point voltage and
The size of zero sequence circulation, it is confirmed whether to rewrite selective harmonic elimination pulsewidth modulation signal, is given birth to by PWM signal generator
Into control signal, the switching device of T-shaped three-level inverter parallel system is controlled；The small vector controller is according to mid-point voltage
Judged, if mid-point voltage in the range of given threshold, does not change the state of switches set, particular harmonic is eliminated pulsewidth and adjust
Signal processed generates control signal by PWM signal generator, controls the switching device of T-shaped three-level inverter parallel system；
If mid-point voltage, not in the range of given threshold, small vector controller changes switches set state, particular harmonic is set to eliminate arteries and veins
Wide modulated signal is changed as small voltage vector, generates control signal by PWM signal generator, controls T-shaped tri-level inversion
The switching device of device parallel system；
When the small vector controller controls according to zero sequence circulation, if zero sequence circulation exceedes threshold range, if zero sequence circulation is more than
Zero, on off state is changed to N-type small vector, if zero sequence circulation is less than zero, on off state is changed to p-type small vector, if zero
In threshold range, on off state does not change sequence circulation.
5. a kind of more T-shaped three-level inverter control method for parallel using SHEPWM as claimed in claim 4, its feature
It is：The half of voltage difference of the mid-point voltage between two series capacitances of DC side of T-shaped three-level inverter.
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| CN114244169A (en) * | 2021-12-16 | 2022-03-25 | 山东大学 | Fractional order-based multi-index cooperative control method and system for three-level inverter |
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