CN106533231B - A kind of control method for eliminating three-level inverter direct current mid-point voltage low-frequency ripple - Google Patents
A kind of control method for eliminating three-level inverter direct current mid-point voltage low-frequency ripple Download PDFInfo
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- CN106533231B CN106533231B CN201611095164.2A CN201611095164A CN106533231B CN 106533231 B CN106533231 B CN 106533231B CN 201611095164 A CN201611095164 A CN 201611095164A CN 106533231 B CN106533231 B CN 106533231B
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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 kind of control methods for eliminating three-level inverter direct current mid-point voltage low-frequency ripple.The method by each switch periods alignment voltage difference detected, it is poor according to the mid-point voltage of real-time detection, one specific residual voltage of real-time compensation, so that the midpoint electric current alignment voltage difference for generating next switch periods carries out quick and complete compensation.The control method of present invention elimination three-level inverter direct current mid-point voltage low-frequency ripple: (1) balance of three-level inverter mid-point voltage can effectively and be quickly realized;(2) it can effectively eliminate the low-frequency ripple of mid-point voltage;(3) control method realizes very simple that calculation amount is small.
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
The control method of converting means elimination direct current mid-point voltage low-frequency ripple.
Background technique
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 electricity
The precondition that flat neutral-point-clamped type inverter can work normally is that mid-point voltage keeps balance.Mid-point voltage imbalance can be led
It causes output voltage current harmonic content to increase, if voltage fluctuation degree is violent or larger steady-state deviation occurs, will lead to bridge arm and open
It closes tube voltage stress to increase, switching tube excessive pressure damages may be made.There is also intrinsic low-frequency ripples for mid-point voltage simultaneously, this low
Frequency ripple will lead to output voltage and current harmonics increases, if ripple amplitude is excessive may also to damage switching device.
When the clamped type three-level inverter in midpoint is controlled using traditional SPWM or SVPWM method, can it lead
Mid-point voltage is caused to generate the low-frequency voltage ripple of intrinsic three times fundamental frequency.Aiming at the problem that mid-point voltage low-frequency ripple, current
Major programme is to pass through in adjusting in real time to adjust zero in real time in the distribution ratio, SPWM scheme of small vector in SVPWM modulation respectively
Sequence voltage injection rate weakens low-frequency ripple.However all there is extremely complex sector judgement in the above method, often relate to very
More formula calculates, and logic and calculating are extremely complex.
There is also various problems in terms of the control of three-level inverter mid-point voltage low-frequency ripple at present, and these problems are still
It is not resolved.
Summary of the invention
In terms of the mid-point voltage present in traditional three-level inverter has low-frequency ripple, the present invention is provided
It is a kind of to calculate control method that is simple and can effectively eliminate three-level inverter direct current mid-point voltage low-frequency ripple.
Specifically, the present invention provides a kind of controlling parties for eliminating three-level inverter direct current mid-point voltage low-frequency ripple
Method, which is characterized in that the three-level inverter includes DC power supply, 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 Dc2And three-phase alternating current load, A phase switching tube Sa1~Sa4, A phase catching diode Da1And Da2Form the clamped type in A phase midpoint
Bridge arm;B phase switching tube Sb1~Sb4, B phase catching diode Db1And Db2Form the clamped type bridge arm in B phase midpoint;C phase switching tube Sc1~
Sc4, C phase catching diode Dc1And Dc2The clamped type bridge arm in C phase midpoint is formed, the midpoint of three bridge arms is both connected to DC side pressure stabilizing
On the midpoint of capacitor C1 and C2, the positive ends of three bridge arms are connected to the anode of the DC power supply, and negative polarity end connects
It is connected to the cathode of the DC power supply, exchange end is respectively connected to a, b, c endpoint of load,
The method by each switch periods alignment voltage difference detected, according to the midpoint of real-time detection electricity
Pressure difference, one specific residual voltage of real-time compensation, thus the midpoint electric current alignment voltage difference for generating next switch periods
Carry out quick and complete compensation.
Further, the method includes the following steps:
(1) DC side electric capacity of voltage regulation C1 and C2 both end voltage are sampled, calculates and eliminates the zero-sequence current component that ripple needs, zero
Sequence current component i* NPCalculation formula are as follows:
(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 value vmax, median vmidWith minimum value vmin;
(3) sampling three-phase exports electric current ia, ib, ic, and size judgement is carried out to three, respectively obtain three-phase output electric current
Middle maximum value imax, median imidWith minimum value imin;
(4) intermediate midpoint electric current i is calculated0mid, calculation formula is as follows:
i0mid=(1-vmax+vmid)imax+(1+vmin-vmid)imin+imid
(5) conversion coefficient k is calculated1And k2, calculation formula is as follows:
(6) the zero sequence voltage component v for needing to inject is calculated0, calculation formula is as follows:
There are two types of expression formulas for formula (VIII), in each switch periods according to the actual situation, one of which are selected to calculate
Residual voltage, logic select table as follows:
The advantages of control method of the present invention, is:
(1) balance of three-level inverter mid-point voltage effectively and is quickly realized;
(2) it can effectively eliminate the low-frequency ripple of mid-point voltage;
(3) control method realizes very simple that calculation amount is small;
Detailed description of the invention
Fig. 1 is the topology diagram for the three-phase tri-level inverter that the present invention is applied to;
Fig. 2 is the residual voltage waveform that control method of the present invention is injected under a kind of operating condition;
Fig. 3 is using the method for the present invention and traditional control method mid-point voltage comparison of wave shape;
Specific embodiment
Below in conjunction with attached drawing and embodiment, the present invention is described in detail, but not therefore by protection model of the invention
It encloses and is limited among the range of embodiment description.
The present invention will be further explained below with reference to the attached drawings.
Fig. 1 is three-phase tri-level inverter topology figure.As shown in Figure 1, the three-phase tri-level inverter includes straight
Galvanic electricity source 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 tube
Sb1~Sb4, B phase catching diode Db1And Db2, C phase switching tube Sc1~Sc4, C phase catching diode Dc1And Dc2And three intersection
Current load.A phase switching tube Sa1~Sa4, A phase catching diode Da1And Da2Form the clamped type bridge arm in A phase midpoint;B phase switching tube Sb1
~Sb4, B phase catching diode Db1And Db2Form the clamped type bridge arm in B phase midpoint;C phase switching tube Sc1~Sc4, C phase catching diode
Dc1And Dc2Form the clamped type bridge arm in C phase midpoint.The inverter further includes control module, and control module controls signal for generating,
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 condition.As shown in Fig. 2, three-phase
When three-level inverter is modulated according to traditional SPWM modulator approach, carrier wave VcaIt is by horizontal symmetrical two groups about y=0
Triangle wave component, triangle wave amplitude are 1, and frequency is switching frequency fs.Conventional modulated wave VrIt is symmetrical just about y=0 level
String wave, expression formula such as (I) is shown,
Wherein ω is fundamental wave frequency, and switching tube conduction mode is carried out by following formula,
Shown in the expression formula such as formula (III) for obtaining midpoint electric current by traditional modulation, iNPIndicate outflow inverter midpoint
Electric current, ia, ibAnd icIt is three-phase inverter output current phase respectively, which is the letter fluctuated according to three times fundamental frequency
Number, therefore mid-point voltage is caused to generate three times fundamental frequency low-frequency ripple,
Control method of the present invention injects specific zero sequence voltage component v in conventional modulated wave0, make midpoint electric current
Expression formula are as follows:
Zero sequence voltage component v of the invention0It is generated as steps described below in each switch periods,
(1) electric capacity of voltage regulation C1 and C2 both end voltage is sampled, calculates and eliminates the zero-sequence current component that ripple needs,
As midpoint voltage difference delta 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 generate midpoint electric current and carry out charge and discharge to C1 and C2, and the voltage difference of two capacitors is made to pass through one
Switch periods TsAfter revert to zero, it is therefore desirable to zero-sequence current component i* NPExpression formula are as follows:
(2) sampling three-phase voltage va, vb, vc, and size judgement is carried out, respectively obtain maximum value v in three-phase voltagemax, in
Between value vmidAnd minimum value vmin;
(3) sampling three-phase electric current ia, ib, ic, and size judgement is carried out, respectively obtain maximum value i in three-phase currentmax, in
Between value imidAnd minimum value imin;
(4) intermediate midpoint electric current i is calculated0mid, expression formula is as follows:
i0mid=(1-vmax+vmid)imax+(1+vmin-vmid)imin+imid (VI)
(5) conversion coefficient k is calculated1And k2, expression formula is as follows:
(6) the zero sequence voltage component v for needing to inject is calculated0, expression formula is as follows:
There are two types of expression formulas for formula (VIII), in each switch periods according to the actual situation, one of which are selected to calculate
Residual voltage, logic select table as follows:
The method of the invention alignment voltage difference in each switch periods is detected, according to the midpoint of real-time detection electricity
Pressure difference, one specific residual voltage of real-time compensation, thus the midpoint electric current alignment voltage difference for generating next switch periods
Quick and complete compensation is carried out, to guarantee that mid-point voltage keeps balance in each switch periods, to eliminate low-frequency voltage
Ripple.
Fig. 3 shows method application front and back mid-point voltage simulation waveform comparison of the invention.Simulation parameter are as follows: switching frequency
15kHz, alternating voltage fundamental frequency 50Hz, line voltage virtual value are 380V, DC voltage VdcFor 700V, load as 4.28mH electricity
Feel 25 Europe resistance, modulation ratio m is that 1, C1 and C2 is 470uF, and mid-point voltage difference Δ V is 100V.
From figure 3, it can be seen that traditional control method needs about 0.2s that can just be adjusted to when midpoint voltage difference has 100V
Balance, and great low-frequency ripple is still had when stable state, ripple peak-to-peak value is about 35V;After the method for the present invention, midpoint electricity
Pressure is promptly restored to balance, and recovery time is only 0.015s, and speed improves more than 10 times, and mid-point voltage low-frequency ripple is complete when stable state
It 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 according to embodiment and attached drawing public affairs
Open content, the present invention can be implemented using other a variety of specific embodiments, therefore, it is all using design structure of the invention and
Thinking does the design of some simple transformation or change, both falls within the scope of protection of the invention.
Although the principle of the present invention is described in detail above in conjunction with the preferred embodiment of the present invention, this field skill
Art personnel are it should be understood that above-described embodiment is only the explanation to exemplary implementation of the invention, not to present invention packet
Restriction containing range.Details in embodiment is simultaneously not meant to limit the scope of the invention, without departing substantially from spirit of the invention and
In the case where range, any equivalent transformation based on technical solution of the present invention, simple replacement etc. obviously change, and all fall within
Within the scope of the present invention.
Claims (1)
1. a kind of control method for eliminating three-level inverter direct current mid-point voltage low-frequency ripple, which is characterized in that three electricity
Flat inverter includes DC power supply, 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 Da2Form the clamped type bridge arm in A phase midpoint;B phase switching tube Sb1~Sb4, B
Phase catching diode Db1And Db2Form the clamped type bridge arm in B phase midpoint;C phase switching tube Sc1~Sc4, C phase catching diode Dc1And Dc2
The clamped type bridge arm in C phase midpoint is formed, the midpoint of three bridge arms is both connected on the midpoint of DC side electric capacity of voltage regulation C1 and C2, and three
The positive ends of bridge arm are connected to the anode of the DC power supply, and negative polarity end is connected to the cathode of the DC power supply,
Ac output end is respectively connected to a, b, c endpoint of load,
The method by each switch periods alignment voltage difference detected, according to the mid-point voltage of real-time detection
Difference, one specific residual voltage of real-time compensation, thus the midpoint electric current alignment voltage difference for generating next switch periods into
The quick and complete compensation of row,
The method includes the following steps:
(1) DC side electric capacity of voltage regulation C1 and C2 both end voltage are sampled, calculates and eliminates the zero-sequence current component that ripple needs, zero sequence electricity
Flow component i* NPCalculation formula are as follows:
Vc1And Vc2It is electric capacity of voltage regulation C1 and C2 both end voltage, T respectivelysFor switch periods;
(2) sampling three-phase output voltage va, vb, vc, and size judgement is carried out to three, it respectively obtains in three-phase output voltage
Maximum value vmax, median vmidWith minimum value vmin;
(3) sampling three-phase exports electric current ia, ib, ic, and size judgement is carried out to three, it respectively obtains in three-phase output electric current most
Big value imax, median imidWith minimum value imin;
(4) the intermediate midpoint electric current i of two capacitors is calculated0mid, calculation formula is as follows:
i0mid=(1-vmax+vmid)imax+(1+vmin-vmid)imin+imid
(5) conversion coefficient k is calculated1And k2, calculation formula is as follows:
(6) the zero sequence voltage component v for needing to inject is calculated0, calculation formula is as follows:
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CN108683351B (en) * | 2018-06-08 | 2019-10-18 | 山东大学 | Hybrid modulation method, controller and the system of a kind of source Z three-level inverter |
CN111245279B (en) * | 2020-03-16 | 2021-06-11 | 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 |
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