CN109617440A - Three-level inverter DC side neutral point voltage balance method based on SVPWM - Google Patents
Three-level inverter DC side neutral point voltage balance method based on SVPWM Download PDFInfo
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- CN109617440A CN109617440A CN201811516424.8A CN201811516424A CN109617440A CN 109617440 A CN109617440 A CN 109617440A CN 201811516424 A CN201811516424 A CN 201811516424A CN 109617440 A CN109617440 A CN 109617440A
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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
- 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
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- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The present invention proposes a kind of three-level inverter DC side neutral point voltage balance method based on SVPWM, the control vector for influencing three level neutral point voltage balances is controlled using corresponding method, for middle vector control use virtual vector, synthesized with big vector of the alignment voltage without influence in vector；And to the control of small vector using the synthesis time of PI control small vector；Two kinds of control methods combine, and after the improvement that centering vector sum small vector carries out, and carry out closed loop feedback control, improve three level mid-point voltage dynamical balance features, meet system stability requirement；Additional auxiliary circuit is not needed, reduces current transformer loss, improves the stability of three-level inverter device dc-voltage balance, control method is simple.
Description
Technical field
The present invention relates to the DC side neutral point voltage balance methods of three-level inverter, more particularly to one kind to be based on SVPWM
Three-level inverter DC side neutral point voltage balance method.
Background technique
In order to reach three-level inverter DC side neutral point voltage balance, traditional method is additional auxiliary circuit to realize
Neutral point voltage balance, but entire circuit and control algolithm can become more complicated after improving circuit；Traditional control synthesizes arrow
Voltage action time method is measured, is easy to cause Vector modulation action time too small, switchs frequent switching and surge voltage, spike electricity
The appearance of stream.Therefore, it is necessary to be improved to this method, to overcome drawbacks described above.
Summary of the invention
The three-level inverter DC side neutral point voltage balance method based on SVPWM that the object of the present invention is to provide a kind of,
To improve level mid-point voltage imbalance problem, the dynamic stability of equipment is improved, guarantees the normal fortune of the electrical equipments such as motor
Row.
The present invention is that technical solution used by solving its technical problem is:
Three-level inverter DC side neutral point voltage balance method based on SVPWM, comprising the following steps:
Space voltage vector region is divided first, it will according to the switching tube turn-on sequence of diode clamping three-level inverter
Space voltage vector region division is six big vector areas, and each big vector area is divided into four small vector regions again, always
It is made of altogether 27 vectors；The three-level inverter formed by diode clamping is altogether by 12 switching tubes, wherein every circuitry phase contains 4
A switching tube, by analyzing the turn-on sequence of every phase switching tube, obtaining every phase switching tube has Udc/2、0、-Udc/ 2 three kinds of voltage shapes
State, so sharing 3 in three-phase circuit3Different states, is then distributed on certain position by=27 kinds of switch states, then into
The division of row zonule；
The influence of zero vector, positive small vector, negative small vector, middle vector to three level mid-point voltages is listed respectively, works as input
When vector is zero vector PPP, load-side is connected with P point to be not attached to midpoint m, so alignment voltage is without influence；When input just
When small vector POO, load surveys the end a and is connected with P point, and the both ends b, c loaded are connected with midpoint m, is generated by DC voltage
Piezoelectric voltage is uneven；When inputting negative small vector ONN, load-side connect with positive small vector and communicates, but electric current iz flows out midpoint
M declines capacitor C2 voltage, and C1 voltage rises, and meets C2 < C1, causes mid-point voltage uneven；As vector PON in input,
Load-side is connected with P point, midpoint m, N point respectively, and the electric current for flowing into midpoint existing at this time also has the electric current in outflow, finally,
To zero vector, big vector alignment voltage without influence, middle vector sum small vector, which balances it, to be had an impact；
In order to allow mid-point voltage to reach balance, centering vector sum small vector is needed to improve, for produced by small vector
Imbalance, change the control action time of positive and negative small vector, make positive small vector action time and negative small vector as far as possible
Action time is equal, cancels out each other, and makes neutral point voltage balance, for this purpose, introducing midpoint regulatory factor ρ, redistributes V1p、V1n's
Action time:
It carries it into the comparison point of SVPWM and obtains:
E is unbalance of neutral-point voltage amount；
Work as Vc1=Vc2When=0, ρ=0；Work as Vc1> Vc2When, ρ < 0；Work as Vc1< Vc2When, ρ > 0；
Deviator amendment is carried out to it using pi regulator:
ρ ∈ [- 11], wherein Δ U (t) is Uc1With Uc2Difference；
By closed-loop control, the size of regulatory factor ρ is constantly adjusted, mid-point voltage is made to reach balance；For middle vector
Adjustment, using virtual vector method, i.e., middle vector is synthesized by adjacent big vector according to Vector triangle, middle vectorIt is by swearing greatly
AmountWithSynthesis, it is defined asFormer vectorIndicate the switch state of three-phase bridge arm,It indicates the new vector synthesized by PPN, PNN, circuit map analysis inflow and outflow midpoint electricity is drawn according to above three switching vector selector
Stream, obtains Ia+Ib+Ic=0, so that entire virtual middle vector action time alignment is without influence.
After carrying out a series of improvement by centering vector sum small vector above, and closed loop feedback control is carried out, in three level
The dynamical balance feature of point voltage is more stable, and anti-interference is stronger.
The present invention has the advantages that
The control vector for influencing three level neutral point voltage balances is controlled using corresponding method, for middle vector
Control use virtual vector, synthesized with big vector of the alignment voltage without influence in vector；And the control of small vector is used
The synthesis time of PI control small vector；Two kinds of control methods combine, after the improvement that centering vector sum small vector carries out, and
Closed loop feedback control is carried out, three level mid-point voltage dynamical balance features are improved, meets system stability requirement；It does not need additional
Auxiliary circuit reduces current transformer loss, improves the stability of three-level inverter device dc-voltage balance, control method
Simply.
Detailed description of the invention
Fig. 1 is three-level inverter space vector schematic diagram；
Fig. 2 is the voltage vector decomposition diagram of sector I；
Fig. 3 is the influence schematic diagram of different vector alignments；
Fig. 4 is capacitor mid-point voltage control schematic diagram.
Specific embodiment
In order to be easy to understand the technical means, the creative features, the aims and the efficiencies achieved by the present invention, tie below
Diagram and specific embodiment are closed, the present invention is further explained.
Three-level inverter DC side neutral point voltage balance method proposed by the present invention based on SVPWM, including following step
It is rapid:
Space voltage vector region is divided first, it will according to the switching tube turn-on sequence of diode clamping three-level inverter
Space voltage vector region division is six big vector areas, and each big vector area is divided into four small vector regions again, always
It is made of altogether 27 vectors；Such as Fig. 1, the three-level inverter formed by diode clamping is altogether by 12 switching tubes, wherein every phase
Circuit contains 4 switching tubes, and by analyzing the turn-on sequence of every phase switching tube, obtaining every phase switching tube has Udc/2、0、-Udc/ 2 three
Kind voltage status, so sharing 3 in three-phase circuit3Different states, is then distributed in certain position by=27 kinds of switch states
It sets, as Fig. 2 carries out the division of zonule again；
As shown in figure 3, listing zero vector, positive small vector, negative small vector, middle vector respectively to the shadows of three level mid-point voltages
It rings, when input vector is zero vector PPP, load-side is connected with P point to be not attached to midpoint m, so alignment voltage is without influence；
When inputting positive small vector POO, load surveys the end a and is connected with P point, and the both ends b, c loaded are connected with midpoint m, by DC side electricity
Press the piezoelectric voltage generated uneven；When inputting negative small vector ONN, load-side connect with positive small vector and communicates, but electric current iz
Midpoint m is flowed out, capacitor C2 voltage is declined, C1 voltage rises, and meets C2 < C1, causes mid-point voltage uneven；When being sweared in input
When measuring PON, load-side is connected with P point, midpoint m, N point respectively, and the electric current for flowing into midpoint existing at this time also has the electric current in outflow,
Finally, obtaining zero vector, big vector alignment voltage without influence, middle vector sum small vector, which balances it, to be had an impact；
As Fig. 4 needs centering vector sum small vector to improve, for small vector to allow mid-point voltage to reach balance
Generated imbalance changes the control action time of positive and negative small vector, make as far as possible positive small vector action time with bear it is small
The action time of vector is equal, cancels out each other, and makes neutral point voltage balance, for this purpose, introducing midpoint regulatory factor ρ, redistributes V1p、
V1nAction time:
It carries it into the comparison point of SVPWM and obtains:
E is unbalance of neutral-point voltage amount；
Work as Vc1=Vc2When=0, ρ=0；Work as Vc1> Vc2When, ρ < 0；Work as Vc1< Vc2When, ρ > 0；
Deviator amendment is carried out to it using pi regulator:
ρ ∈ [- 11], wherein Δ U (t) is Uc1With Uc2Difference；
By the closed-loop control in Fig. 4, the size of regulatory factor ρ is constantly adjusted, mid-point voltage is made to reach balance；For in
The adjustment of vector, using virtual vector method, i.e., middle vector is synthesized by adjacent big vector according to Vector triangle, such as Fig. 2, middle arrow
AmountIt is by big vectorWithSynthesis, it is defined asFormer vectorIndicate three-phase bridge
The switch state of arm,It indicates the new vector synthesized by PPN, PNN, circuit map analysis is drawn according to above three switching vector selector
Inflow and outflow midpoint electric current, obtains Ia+Ib+Ic=0, so that entire virtual middle vector action time alignment is without influence.
Embodiment of above only technical concepts and features to illustrate the invention, its object is to allow those skilled in the art
Member understands the contents of the present invention and is implemented, and it is not intended to limit the scope of the present invention, all spiritual according to the present invention
The equivalent change or modification that essence is done, should be covered by the scope of protection of the present invention.
Claims (1)
1. the three-level inverter DC side neutral point voltage balance method based on SVPWM, which comprises the following steps:
Space voltage vector region is divided first, according to the switching tube turn-on sequence of diode clamping three-level inverter by space
Voltage vector region division is six big vector areas, and each big vector area is divided into four small vector regions, Zong Gongyou again
27 vector compositions；The three-level inverter formed by diode clamping is altogether by 12 switching tubes, wherein every circuitry phase is opened containing 4
Guan Guan, by analyzing the turn-on sequence of every phase switching tube, obtaining every phase switching tube has Udc/2、0、-Udc/ 2 three kinds of voltage status,
So sharing 3 in three-phase circuit3Different states, is then distributed on certain position by=27 kinds of switch states, then carries out
The division of zonule；
The influence of zero vector, positive small vector, negative small vector, middle vector to three level mid-point voltages is listed respectively, works as input vector
When for zero vector PPP, load-side is connected with P point to be not attached to midpoint m, so alignment voltage is without influence；When the just small arrow of input
When measuring POO, load surveys the end a and is connected with P point, and the both ends b, c loaded are connected with midpoint m, the electricity electricity generated by DC voltage
Pressure is uneven；When inputting negative small vector ONN, load-side connect with positive small vector and communicates, but electric current iz flows out midpoint m, makes
The decline of capacitor C2 voltage, C1 voltage rise, and meet C2 < C1, cause mid-point voltage uneven；As vector PON in input, load
Side is connected with P point, midpoint m, N point respectively, and the electric current for flowing into midpoint existing at this time also has the electric current in outflow, finally, obtaining zero
Without influence, middle vector sum small vector, which balances it, to be had an impact for vector, big vector alignment voltage；
In order to allow mid-point voltage to reach balance, centering vector sum small vector is needed to improve, for caused by small vector not
Balance, changes the control action time of positive and negative small vector, makes the effect of positive small vector action time and negative small vector as far as possible
Time is equal, cancels out each other, and makes neutral point voltage balance, for this purpose, introducing midpoint regulatory factor ρ, redistributes V1p、V1nEffect
Time:
It carries it into the comparison point of SVPWM and obtains:
E is unbalance of neutral-point voltage amount；
Work as Vc1=Vc2When=0, ρ=0；Work as Vc1> Vc2When, ρ < 0；Work as Vc1< Vc2When, ρ > 0；
Deviator amendment is carried out to it using pi regulator:
Wherein Δ U (t) is Uc1With Uc2Difference；
By closed-loop control, the size of regulatory factor ρ is constantly adjusted, mid-point voltage is made to reach balance；
Adjustment for middle vector, using virtual vector method, i.e., middle vector is synthesized by adjacent big vector according to Vector triangle,
Middle vectorIt is by big vectorWithSynthesis, it is defined asFormer vectorIndicate three
The switch state of phase bridge arm,It indicates the new vector synthesized by PPN, PNN, circuit diagram is drawn according to above three switching vector selector
Inflow and outflow midpoint electric current is analyzed, obtains Ia+Ib+Ic=0, so that entire virtual middle vector action time alignment is without influence.
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Cited By (4)
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| CN111030495A (en) * | 2019-12-30 | 2020-04-17 | 东北农业大学 | Method and system for balancing neutral point voltage of four-partition-based three-level inverter |
| CN111092562A (en) * | 2020-01-09 | 2020-05-01 | 东北农业大学 | Three-partition-type-based control method and system for midpoint voltage of three-level inverter |
| CN111181429A (en) * | 2020-01-09 | 2020-05-19 | 东北农业大学 | Three-partition-based three-level inverter neutral-point voltage balancing method and system |
| CN113037110A (en) * | 2021-02-25 | 2021-06-25 | 安徽大学绿色产业创新研究院 | Five-level inverter midpoint voltage control method |
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Cited By (5)
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| CN111030495A (en) * | 2019-12-30 | 2020-04-17 | 东北农业大学 | Method and system for balancing neutral point voltage of four-partition-based three-level inverter |
| CN111092562A (en) * | 2020-01-09 | 2020-05-01 | 东北农业大学 | Three-partition-type-based control method and system for midpoint voltage of three-level inverter |
| CN111181429A (en) * | 2020-01-09 | 2020-05-19 | 东北农业大学 | Three-partition-based three-level inverter neutral-point voltage balancing method and system |
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| CN113037110A (en) * | 2021-02-25 | 2021-06-25 | 安徽大学绿色产业创新研究院 | Five-level inverter midpoint voltage control method |
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