CN106533231A - Control method for eliminating low-frequency ripple of mid-point voltage of DC of three-level inverter - Google Patents
Control method for eliminating low-frequency ripple of mid-point voltage of DC of three-level inverter Download PDFInfo
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- CN106533231A CN106533231A CN201611095164.2A CN201611095164A CN106533231A CN 106533231 A CN106533231 A CN 106533231A CN 201611095164 A CN201611095164 A CN 201611095164A CN 106533231 A CN106533231 A CN 106533231A
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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
-
- 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
- H02M1/14—Arrangements for reducing ripples from dc input or output
- H02M1/143—Arrangements for reducing ripples from dc input or output using compensating arrangements
-
- 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
- H02M7/5387—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 in a bridge configuration
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a control method for eliminating a low-frequency ripple of mid-point voltage of DC of a three-level inverter. According to the method, a mid-point voltage difference is detected in each switching period, and specific zero-sequence voltage is compensated in real time according to the mid-point voltage difference detected in real time, so that fast complete compensation is carried out on the mid-point voltage difference by mid-point current generated in the next switching period. The control method for eliminating the low-frequency ripple of the mid-point voltage of the DC of the three-level inverter has the advantages that (1) balancing of the mid-point voltage of the three-level inverter can be effectively and quickly achieved; (2) the low-frequency ripple of the mid-point voltage can be effectively eliminated; and (3) the control method is very simple to implement and small in computing quantity.
Description
Technical field
The present invention relates to three level DC-AC energy converting means, and in particular to a kind of three level DC-AC energy
Converting means eliminates the control method of direct current mid-point voltage low-frequency ripple.
Background technology
Multi-electrical level inverter can reduce the harmonic content of output voltage, reduce the voltage stress of switching device, in high pressure
Large-power occasions are widely used.Wherein three level neutral-point-clamped type inverters are studied and are most widely used.Three is electric
The precondition that flat neutral-point-clamped type inverter is capable of normal work is that mid-point voltage keeps balance.Mid-point voltage imbalance can be led
Cause output voltage current harmonic content to increase, if voltage pulsation degree is violent or larger steady-state deviation occurs, bridge arm can be caused to hold
Closing tube voltage stress increases, and may make switching tube excessive pressure damages.Also there is intrinsic low-frequency ripple in mid-point voltage simultaneously, this low
Frequency ripple can cause output voltage and current harmonics to increase, if ripple amplitude is excessive to be likely to damage switching device.
When the clamped type three-level inverter in midpoint is controlled using traditional SPWM or SVPWM method, can lead
Mid-point voltage is caused to produce the low-frequency voltage ripple of intrinsic three times fundamental frequency.It is for the problem of mid-point voltage low-frequency ripple, current
Major programme be respectively in SVPWM modulation by the distribution ratio of small vector, SPWM schemes in real-time regulation in real-time regulation zero
Sequence voltage injection rate is weakening low-frequency ripple.But all be present extremely complex sector and judge in said method, often relate to very
Many formula are calculated, and logical sum calculates extremely complex.
At present the control aspect of three-level inverter mid-point voltage low-frequency ripple also there is a problem of a variety of, and these problems are still
It is not resolved.
The content of the invention
In terms of there is low-frequency ripple for the mid-point voltage existing for traditional three-level inverter, the present invention is provided
It is a kind of to calculate control method that is simple and effectively eliminating three-level inverter direct current mid-point voltage low-frequency ripple.
Specifically, the invention provides a kind of controlling party for eliminating three-level inverter direct current mid-point voltage low-frequency ripple
Method, it is characterised in that the three-level inverter includes DC source, DC side electric capacity of voltage regulation C1 and C2, A phase catching diode
Da1And Da2, B phase switching tube Sb1～Sb4, B phase catching diode Db1And Db2, C phase switching tube Sc1～Sc4, C phase catching diode Dc1
And Dc2, and three-phase alternating current load, A phase switching tube Sa1～Sa4, A phase catching diode Da1And Da2The clamped type in composition A phases midpoint
Bridge arm；B phase switching tube Sb1～Sb4, B phase catching diode Db1And Db2The clamped type bridge arm in composition B phases midpoint；C phase switching tube Sc1~
Sc4, C phase catching diode Dc1And Dc2The clamped type bridge arm in composition C phases midpoint, the midpoint of three bridge arms is both connected to DC side voltage stabilizing
On the midpoint of electric capacity C1 and C2, the positive ends of three bridge arms are connected to the positive pole of the DC source, and negative polarity end connects
The negative pole of the DC source is connected to, a, b, c end points that end is respectively connecting to load is exchanged,
Methods described is detected by the alignment voltage difference in each switch periods, according to the midpoint electricity of real-time detection
Pressure reduction, the specific residual voltage of real-Time Compensation one, so that the midpoint electric current alignment voltage difference that next switch periods are produced
Carry out quick and complete compensation.
Further, methods described comprises the steps：
(1) sampling DC side electric capacity of voltage regulation C1 and C2 both end voltage, the zero-sequence current component that calculating elimination ripple needs, zero
Sequence current component i* NPComputing formula be：
(2) sampling three-phase output voltage va, vb, vc, and size judgement is carried out to three, respectively obtain three-phase output voltage
In maximum vmax, intermediate value vmidWith minima vmin；
(3) sampling three-phase output current ia, ib, ic, and size judgement is carried out to three, respectively obtain three-phase output current
Middle maximum imax, intermediate value imidWith minima imin；
(4) midpoint electric current i in the middle of calculating0mid, its computing formula is as follows：
i0mid=(1-vmax+vmid)imax+(1+vmin-vmid)imin+imid
(5) calculate conversion coefficient k1And k2, its computing formula is as follows：
(6) calculating needs the zero sequence voltage component v of injection0, its computing formula is as follows：
Formula (VIII) has two kinds of expression formulas, according to practical situation in each switch periods, selects one of which to calculate
Residual voltage, logic select table as follows：
The advantage of control method of the present invention is：
(1) balance that is effective and quickly realizing three-level inverter mid-point voltage；
(2) low-frequency ripple of mid-point voltage can effectively be eliminated；
(3) control method realizes that very simply amount of calculation is little；
Description of the drawings
Fig. 1 is the topology diagram of the three-phase tri-level inverter is applied to by the present invention；
Fig. 2 is the residual voltage waveform that control method of the present invention is injected under a kind of operating mode；
Fig. 3 is using the inventive method and traditional control method mid-point voltage comparison of wave shape；
Specific embodiment
Below in conjunction with accompanying drawing and embodiment, the present invention is described in detail, but not therefore by the protection model of the present invention
Enclose among being limited in the scope of embodiment description.
The invention will be further described below in conjunction with the accompanying drawings.
Fig. 1 is three-phase tri-level inverter topology figure.As shown in figure 1, the three-phase tri-level inverter includes directly
Stream power supply Vdc, DC side electric capacity of voltage regulation C1 and C2, A phase switching tube Sa1～Sa4, A phase catching diode Da1And Da2, B phase switching tubes
Sb1～Sb4, B phase catching diode Db1And Db2, C phase switching tube Sc1～Sc4, C phase catching diode Dc1And Dc2, and three is intersecting
Current load.A phase switching tube Sa1～Sa4, A phase catching diode Da1And Da2The clamped type bridge arm in composition A phases midpoint；B phase switching tube Sb1
～Sb4, B phase catching diode Db1And Db2The clamped type bridge arm in composition B phases midpoint；C phase switching tube Sc1～Sc4, C phase catching diodes
Dc1And Dc2The clamped type bridge arm in composition C phases midpoint.The inverter also includes control module, and control module is used for generating control signal,
To control all parts in inverter.
Fig. 2 show the residual voltage waveform that control method of the present invention is injected under a kind of operating mode.As shown in Fig. 2 three-phase
When three-level inverter is modulated according to traditional SPWM modulator approaches, carrier wave VcaIt is by with regard to symmetrical two groups of y=0 horizontal lines
Triangle wave component, triangle wave amplitude are 1, and frequency is switching frequency fs.Conventional modulated ripple VrIt is symmetrical just with regard to y=0 horizontal lines
String ripple, its expression formula as shown in (I),
Wherein ω is fundamental wave angular frequency, and its switching tube conduction mode is carried out by following formula,
Obtain by traditional modulation shown in the expression formula such as formula (III) of midpoint electric current, iNPRepresent and flow out inverter midpoint
Electric current, ia, ibAnd icIt is three-phase inverter output current phase respectively, the expression formula is a letter fluctuated according to three times fundamental frequency
Number, therefore cause mid-point voltage to produce three times fundamental frequency low-frequency ripple,
Control method of the present invention injects specific zero sequence voltage component v in conventional modulated ripple0, make midpoint electric current
Expression formula is：
The zero sequence voltage component v of the present invention0Generated in each switch periods as steps described below,
(1) sampling electric capacity of voltage regulation C1 and C2 both end voltage, calculates the zero-sequence current component for eliminating that ripple needs,
As mid-point voltage difference Δ V=Vc1-Vc2In the presence of, wherein Vc1And Vc2It is electric capacity of voltage regulation C1 and C2 both end voltage respectively,
Injection residual voltage should be able to produce midpoint electric current carries out discharge and recharge to C1 and C2, makes the voltage difference of two electric capacity through one
Switch periods TsAfter revert to zero, it is therefore desirable to zero-sequence current component i* NPExpression formula is：
(2) sampling three-phase voltage va, vb, vc, and size judgement is carried out, respectively obtain maximum v in three-phase voltagemax, in
Between value vmid, and minima vmin；
(3) sampling three-phase electric current ia, ib, ic, and size judgement is carried out, respectively obtain maximum i in three-phase currentmax, in
Between value imid, and minima imin；
(4) midpoint electric current i in the middle of calculating0mid, its expression formula is as follows：
i0mid=(1-vmax+vmid)imax+(1+vmin-vmid)imin+imid (VI)
(5) calculate conversion coefficient k1And k2, its expression formula is as follows：
(6) calculating needs the zero sequence voltage component v of injection0, its expression formula is as follows：
Formula (VIII) has two kinds of expression formulas, according to practical situation in each switch periods, selects one of which to calculate
Residual voltage, logic select table as follows：
Method of the present invention alignment voltage difference in each switch periods is detected, according to the midpoint electricity of real-time detection
Pressure reduction, the specific residual voltage of real-Time Compensation one, so that the midpoint electric current alignment voltage difference that next switch periods are produced
Quick and complete compensation is carried out, so as to ensure that mid-point voltage keeps balance in each switch periods, so as to eliminate low-frequency voltage
Ripple.
Fig. 3 shows mid-point voltage simulation waveform contrast before and after method of the present invention application.Simulation parameter is：Switching frequency
15kHz, alternating voltage fundamental frequency 50Hz, line voltage virtual value are 380V, DC voltage VdcFor 700V, load for 4.28mH it is electric
Feel 25 Europe resistance, modulation ratio m is 470uF for 1, C1 and C2, and mid-point voltage difference Δ V is 100V.
From figure 3, it can be seen that when mid-point voltage difference has 100V, traditional control method need about 0.2s could adjust to
Balance, and great low-frequency ripple during stable state, is yet suffered from, ripple peak-to-peak value is about 35V；After the inventive method, midpoint electricity
Pressure is promptly restored to balance, and recovery time is only 0.015s, and speed improves more than 10 times, and during stable state, mid-point voltage low-frequency ripple is complete
Totally disappeared and remove, the maximum peak-to-peak value of mid-point voltage fluctuation is within 1V.
The present invention is not only limited to above-mentioned specific embodiment, and persons skilled in the art are public according to embodiment and accompanying drawing
Open content, the present invention can be implemented using other various specific embodiments, therefore, every design structure using the present invention and
Thinking, does some simple conversion or the design changed, both falls within the scope of protection of the invention.
Although being described in detail to the principle of the present invention above in conjunction with the preferred embodiments of the present invention, this area skill
Art personnel are it should be understood that above-described embodiment explanation only to the exemplary implementation of the present invention, not wraps to the present invention
Restriction containing scope.Details in embodiment is simultaneously not meant to limit the scope of the invention, in the spirit without departing substantially from the present invention and
It is in the case of scope, any to change based on the equivalent transformation of technical solution of the present invention, simple replacement etc. are obvious, all fall within
Within the scope of the present invention.
Claims (2)
1. it is a kind of eliminate three-level inverter direct current mid-point voltage low-frequency ripple control method, it is characterised in that described three is electric
Flat inverter includes DC source, DC side electric capacity of voltage regulation C1 and C2, A phase catching diode Da1And Da2, B phase switching tube Sb1~
Sb4, B phase catching diode Db1And Db2, C phase switching tube Sc1～Sc4, C phase catching diode Dc1And Dc2And three-phase alternating current load,
A phase switching tube Sa1～Sa4, A phase catching diode Da1And Da2The clamped type bridge arm in composition A phases midpoint；B phase switching tube Sb1～Sb4, B
Phase catching diode Db1And Db2The clamped type bridge arm in composition B phases midpoint；C phase switching tube Sc1～Sc4, C phase catching diode Dc1And Dc2
The clamped type bridge arm in composition C phases midpoint, the midpoint of three bridge arms are both connected on the midpoint of DC side electric capacity of voltage regulation C1 and C2, three
The positive ends of bridge arm are connected to the positive pole of the DC source, and negative polarity end is connected to the negative pole of the DC source,
Ac output end is respectively connecting to a, b, c end points for loading,
Methods described is detected by the alignment voltage difference in each switch periods, according to the mid-point voltage of real-time detection
Difference, the specific residual voltage of real-Time Compensation one, so that the midpoint electric current alignment voltage difference that next switch periods are produced is entered
The quick and complete compensation of row.
2. three-level inverter direct current neutral-point voltage balance method according to claim 1, it is characterised in that described
Method comprises the steps：
(1) sampling DC side electric capacity of voltage regulation C1 and C2 both end voltage, calculates the zero-sequence current component for eliminating that ripple needs, zero sequence electricity
Flow component i* NPComputing formula be：
Vc1And Vc2It is electric capacity of voltage regulation C1 and C2 both end voltage respectively, TsFor switch periods；
(2) sampling three-phase output voltage va, vb, vc, and size judgement is carried out to three, respectively obtain in three-phase output voltage
Maximum vmax, intermediate value vmidWith minima vmin；
(3) sampling three-phase output current ia, ib, ic, and size judgement is carried out to three, is respectively obtained in three-phase output current most
Big value imax, intermediate value imidWith minima imin；
(4) calculate the middle midpoint electric current i of two electric capacity0mid, its computing formula is as follows：
i0mid=(1-vmax+vmid)imax+(1+vmin-vmid)imin+imid
(5) calculate conversion coefficient k1And k2, its computing formula is as follows：
(6) calculating needs the zero sequence voltage component v of injection0, its computing formula is as follows：
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Cited By (5)
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| CN108683351A (en) * | 2018-06-08 | 2018-10-19 | 山东大学 | Hybrid modulation method, controller and the system of a kind of sources Z three-level inverter |
| CN111245279A (en) * | 2020-03-16 | 2020-06-05 | 深圳市盈科互动科技有限公司 | 5-segment SVPWM modulation method |
| CN112039362A (en) * | 2020-08-31 | 2020-12-04 | 深圳市盛弘电气股份有限公司 | Inversion control method and system, controller, inverter and readable storage medium |
| CN112104247A (en) * | 2020-09-08 | 2020-12-18 | 沈阳工业大学 | Neutral-point potential control method for medium-voltage three-level full-power converter of wind generating set |
| CN118589895A (en) * | 2024-08-06 | 2024-09-03 | 西安奇点能源股份有限公司 | Connecting circuit for enhancing topological symmetry of I-type NPC IGBT parallel connection |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112039362A (en) * | 2020-08-31 | 2020-12-04 | 深圳市盛弘电气股份有限公司 | Inversion control method and system, controller, inverter and readable storage medium |
| CN112104247A (en) * | 2020-09-08 | 2020-12-18 | 沈阳工业大学 | Neutral-point potential control method for medium-voltage three-level full-power converter of wind generating set |
| CN118589895A (en) * | 2024-08-06 | 2024-09-03 | 西安奇点能源股份有限公司 | Connecting circuit for enhancing topological symmetry of I-type NPC IGBT parallel connection |
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