CN109347349A - A kind of three level carrier modulator approaches - Google Patents
A kind of three level carrier modulator approaches Download PDFInfo
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- CN109347349A CN109347349A CN201811346498.1A CN201811346498A CN109347349A CN 109347349 A CN109347349 A CN 109347349A CN 201811346498 A CN201811346498 A CN 201811346498A CN 109347349 A CN109347349 A CN 109347349A
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- level
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Classifications
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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
-
- 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
Abstract
The invention discloses a kind of three level carrier modulator approaches, include both of which: when some switch periods internal modulation wave amplitude is lower than particular value, using 1 modulation system of mode, the phase modulating wave is resolved into positive and negative two modulating waves, it is compared with a triangular carrier, the on off sequence of three all power switch tubes of level NPC current transformer is finally obtained, and guarantees the minimum pulse width requirement for meeting every power switch tube.When some switch periods internal modulation wave amplitude is greater than particular value, using 2 modulation system of mode, modulating wave is compared with two with mutually stacking carrier wave, finally obtains the on off sequence of three all power switch tubes of level NPC current transformer, and guarantees the minimum pulse width requirement for meeting power switch tube.The present invention solves the problems, such as the minimum pulse width being likely to occur in the modulation of three level carriers, meanwhile, it is capable to guarantee that exporting phase voltage and line voltage average value does not distort.
Description
Technical field
The invention belongs to Frequency Converter Control technical fields, specifically design a kind of three level carriers for solving the problems, such as minimum pulse width
Modulator approach.
Background technique
With the rapid development of power electronic technique, three level neutral point clamp types (Neutral-point-clamped,
NPC) frequency converter exchange driving, locomotive traction, the large capacities such as wind-power electricity generation, high voltage appearance field using more and more extensive,
And it is continued to develop to low-pressure field.
There is the limitation of minimum service time and minimum turn-off time in power electronic power device, this requires pulsewidth modulations
The pulse width of output cannot be unlimited narrow.When pulsewidth is less than the minimum switch time that power device requires, device cannot be normal
Work.Therefore narrow pulse must be handled, it is made to meet the requirement of minimum pulse width.Current three level NPC Converter
Common pulse duration modulation method be mainly space vector pulse width modulation (Space Vector Pulse width Modulation,
SVPWM) SVPWM and carried based PWM.SVPWM modulation generallys use nearest three vector methods (Nearest Three
Vecotrs, N3V), unavoidably occur minimum pulse width problem in specific region, general use will be less than the arteries and veins of minimum pulse width
The method for filtering out or being extended to minimum pulse width is rushed, but changes the pulse width of a phase, the line voltage that necessarily will cause output is abnormal
Become.The carrier wave pulsewidth for being based on sinusoidal pulse width modulation (Sine Pulse Width Modulation, SPWM) is proposed in some documents
In modulator approach, when burst pulse occurs in the modulation pulse of a certain phase, while eliminating or extending the burst pulse, to other two-phases
Pulse is compensated accordingly, to ensure that the line voltage exported remains unchanged.But this method is needed to three-phase pulse while being carried out
Change, and in some cases, other compensated pulses of two-phase are likely to occur new burst pulse, influence compensation effect.
Summary of the invention
In place of the present invention is in order to solve above-mentioned the shortcomings of the prior art, a kind of minimum pulse width that solves the problems, such as is proposed
Three level carrier modulator approaches are determined according to the size of this switch periods internal modulation wave amplitude using in two kinds of modulating modes
It is a kind of, it is ensured that while solving the problems, such as minimum pulse width, output phase average voltage will not generate distortion, to guarantee output line electricity
Flattening mean value will not distort.
A kind of three level carrier modulator approaches, including two kinds of modulating modes:
In a switch periods, when modulation degree is less than VmWhen or modulation degree be greater than VmBut current carrier period internal modulation wave
VrxWhen amplitude is between [- Vm, Vm], using 1 modulation system of mode, by modulating wave VrxResolve into positive and negative two modulating wave Vrx1
And Vrx2, with the same triangular carrier VcCompare, finally obtains the on off sequence of all power switch tubes.
In a switch periods, when modulation degree is relatively larger than Vm, and current carrier period internal modulation wave VrxAmplitude [-
1 ,-Vm] or [Vm, 1] between when, using 2 modulation system of mode, by modulating wave and two with mutually stacking carrier wave Vc1And Vc2It carries out
Compare, finally obtains the on off sequence of all power switch tubes of all power switch tubes.
When modulation wave amplitude is equal to VmWhen, mode 1 can be used or mode 2 particular value is required according to power switch tube used
Minimum pulse width and the switch periods of carrier modulation determine a zone of reasonableness.
Above-mentioned modulating wave VrxFor per unit value, amplitude range is [- 1,1]；Triangular carrier VcFor per unit value, amplitude range be [-
1,1]；X is current transformer three-phase a, b, c；VmFor the switch of the minimum pulse width and carrier modulation that are required according to power switch tube used
The reasonable value that period determines.
The beneficial effects of the present invention are:
(1) three level carrier modulator approaches of the invention, according to the size of this switch periods internal modulation wave amplitude, using difference
Modulating mode, solve the problems, such as the minimum pulse width being likely to occur.
(2) three level carrier modulator approaches of the invention, the modulation of every phase is relatively independent, is solving the problems, such as the same of minimum pulse width
When, it can guarantee that exporting phase voltage and line voltage average value does not distort.
(3) three level carrier modulator approaches of the invention, according to carried based PWM principle, modulator approach is simply clear, easily
In realization, there is stronger reliability, suitable for three level NPC Converters using high-voltage large-capacity power device.
Detailed description of the invention
Fig. 1 is typical three level NPC Converters topological circuit.
Fig. 2 is the 1 modulation system schematic illustration of mode of three level carrier modulator approaches of the invention.
Fig. 3 a is modulating wave V in three level carrier modulator approaches of the inventionx2 modulation system principle of mode is illustrated when greater than 0
Figure.
Fig. 3 b is modulating wave V in three level carrier modulator approaches of the inventionx2 modulation system principle of mode is illustrated when less than 0
Figure.
The phase voltage and line that the present invention emulates when Fig. 4 a is modulation degree 0.1 in three level carrier modulator approaches of the invention
Voltage oscillogram.
The phase voltage and line that the present invention emulates when Fig. 4 b is modulation degree 0.4 in three level carrier modulator approaches of the invention
Voltage oscillogram.
The phase voltage and line that the present invention emulates when Fig. 4 c is modulation degree 0.8 in three level carrier modulator approaches of the invention
Voltage oscillogram.
Specific embodiment
Embodiments of the present invention are described in further detail with reference to the accompanying drawing.
With typical three level NPC Converters topological circuit shown in Fig. 1, the present invention will be described；In figure, C1 is with C2
DC capacitor, Sa1~Sa4, Sb1~Sb4 and Sc1~Sc4 be respectively frequency converter A, B, C three-phase device for power switching and its
Anti-paralleled diode.
Three level carrier modulator approaches of the invention, including two kinds of modulating modes:
Mode 1: in a switch periods, when modulation degree is less than VmWhen or modulation degree be greater than VmBut in the current carrier period
Modulating wave VrxAmplitude is less than Vm, i.e. modulating wave VrxWhen between [- Vm, Vm], using 1 modulation system of mode.
Mode 2: in a switch periods, when modulation degree is relatively larger than Vm, and current carrier period internal modulation wave VrxWidth
Value is greater than Vm, i.e. modulating wave VrxWhen between [- 1 ,-Vm] or [Vm, 1], using 2 modulation system of mode.
When modulation wave amplitude is equal to VmWhen, the on off sequence of the power switch tube obtained using mode 1 or mode 2 can expire
Sufficient minimum pulse width requirement.
Above-mentioned modulating wave VrxFor per unit value, amplitude range is [- 1,1]；Triangular carrier VcFor per unit value, amplitude range be [-
1,1]；X is current transformer three-phase a, b, c.VmFor particular value, the minimum pulse width required according to power switch tube used and carrier modulation
Switch periods determine a zone of reasonableness value.By taking Sine Modulated as an example, it is assumed that the device for power switching in frequency converter is most
Small pulsewidth is Tmin, carrier cycle Ts, then being less than T in modulation degree or the modulation wave amplitude in the current carrier periodmin/TsWhen,
The minimum pulse width time is less than using the service time that mode 2 calculates device for power switching, so VmIt cannot be less than Tmin/Ts.When
Preceding carrier cycle internal modulation wave amplitude is greater than 0.5-2Tmin/TsWhen, the turn-off time using the calculated power device of mode 1 is small
In the minimum pulse width time, so VmIt is not greater than 0.5-2Tmin/Ts.In conclusion particular value VmValue range be [Tmin/Ts,
0.5-2Tmin/Ts].Such as High voltage power device IGCT, it is normally applied middle minimum pulse width and is set as 100uS, carrier frequency is
When 500Hz, period 2mS, then the range of particular value Vm is [0.05,0.4], which can be set as 0.2.
Mode 1 and the modulation system of mode 2 are illustrated below:
A, 1 modulation system of mode specifically:
Firstly, by modulating wave VrxResolve into positive and negative two modulating wave Vrx1And Vrx2, isolation are as follows:
Then, by two modulating wave Vrx1And Vrx2With the same triangular carrier VcCompare, obtains the phase outputs level signals.
Manner of comparison are as follows:
Work as Vc< Vrx2, three-level current transformer x phase exports positive level；
Work as Vc> Vrx1, three-level current transformer x phase exports negative level；
Work as Vrx2< Vc< Vrx1, three-level current transformer x phase exports zero level.
Finally, obtaining the on off sequence of all power switch tubes according to phase output voltage waveforms.
As shown in Fig. 2, the x phase modulating wave V in a switch periodsxAmplitude is 0.1 and is less than particular value 0.2, according to upper
Modulating wave and carrier wave comparison principle are stated, phase outputs level signals U is obtainedxo.Meanwhile Vrx2With carrier wave VcIt is compared to obtain No. 1 function
The on off sequence PWM1, V of rate switching tuberx1With carrier wave VcIt is compared to obtain the on off sequence PWM2 of No. 2 power switch tubes；No. 1
The on off sequence PWM1 and PWM2 of power switch tube and No. 2 power switch tubes obtain four power in the phase after logical process
The on off sequence of switching tube.
B, 2 modulation system of mode specifically:
Firstly, by modulating wave VrxWith two carrier wave V with mutually stackingc1And Vc2It is compared, obtains phase output level letter
Number, manner of comparison are as follows:
Work as Vrx> Vc1, three-level current transformer x phase exports positive level；
Work as Vrx< Vc2, three-level current transformer x phase exports negative level；
Work as Vc2< Vrx< Vc1, three-level current transformer x phase exports zero level.
Above-mentioned two carrier wave with mutually stacking is all made of per unit value, Vc1Amplitude range be [0,1], Vc2Amplitude range
For [- 1,0], and:
Vc2=Vc1-1 (2)
Then, the on off sequence of all power switch tubes is obtained according to phase output voltage waveforms.
Fig. 3 a and Fig. 3 b are the schematic illustration modulated when wave amplitude is 0.6 and -0.6 using 2 modulation system of mode respectively.
According to above-mentioned modulating wave and carrier wave comparison principle, phase outputs level signals, while V are obtainedrxWith carrier wave Vc1It is compared to obtain 1
Number power switch tube pulse drive signal PWM1, VrxWith carrier wave Vc2It is compared to obtain No. 2 power switch tube pulse drive signals
PWM2, control signal PWM1 and PWM2 obtain the driving signal of four power switch tubes in the phase after logical process.
In order to verify effectiveness of the invention, the verifying that is emulated using simulation of power electronic software PSIM.In model
Take fundamental frequency fo=50Hz, switching frequency fc=600Hz, DC voltage 5000V, upper the following group DC capacitor C1=C2=10mF,
The switching particular value V of two kinds of modulating modesm=0.2, the minimum pulse width that power switch tube used requires is 100uS.Using sine
Pulsewidth carrier modulation modes, A phase modulating wave Vx=sin (ω t), ω are modulation angular frequency, and t is the time, and B, C phase modulate wavelength-division
Advanced and 120 ° of A phase modulating wave later.Fig. 4 a, Fig. 4 b and Fig. 4 c be respectively modulation degree be 0.1,0.4 and 0.8 when three level
No. 1 power tube of NPC frequency converter A phase and No. 2 power tube driving signals, A phase voltage and AB line voltage waveform.
It can be seen that the driving pulse of power tube is wide when modulation degree is respectively 0.1,0.4 and 0.8 in Fig. 4 a, 4b, 4c respectively
Degree is both greater than 100uS, can satisfy the requirement of minimum pulse width.
Claims (3)
1. a kind of three level carrier modulator approaches, it is characterised in that: including two kinds of modulating modes:
In a switch periods, when modulation degree is less than VmWhen or modulation degree be greater than VmBut current carrier period internal modulation wave VrxWidth
When value is between [- Vm, Vm], using 1 modulation system of mode, by modulating wave VrxResolve into positive and negative two modulating wave Vrx1And Vrx2,
With the same triangular carrier VcCompare, finally obtains the on off sequence of all power switch tubes；
In a switch periods, when modulation degree is relatively larger than Vm, and current carrier period internal modulation wave VrxAmplitude [- 1 ,-
Vm] or [Vm, 1] between when, using 2 modulation system of mode, by modulating wave and two with mutually stacking carrier wave Vc1And Vc2Compared
Compared with finally obtaining the on off sequence of all power switch tubes of all power switch tubes；
When modulation wave amplitude is equal to VmWhen, mode 1 or mode 2 can be used；
Above-mentioned modulating wave VrxFor per unit value, amplitude range is [- 1,1]；Triangular carrier VcFor per unit value, amplitude range be [- 1,
1]；X is current transformer three-phase a, b, c；VmFor the minimum pulse width required according to power switch tube used and the switch of carrier modulation week
The reasonable value that phase determines.
2. three level carrier modulator approaches of one kind as described in claim 1, it is characterised in that: 1 modulation system of mode specifically:
Firstly, by modulating wave VrxResolve into positive and negative two modulating wave Vrx1And Vrx2, isolation are as follows:
Then, by two modulating wave Vrx1And Vrx2With the same triangular carrier VcCompare, obtains the phase outputs level signals；Compare
Mode are as follows:
Work as Vc< Vrx2, three-level current transformer x phase exports positive level；
Work as Vc> Vrx1, three-level current transformer x phase exports negative level；
Work as Vrx2< Vc< Vrx1, three-level current transformer x phase exports zero level.
Finally, obtaining the on off sequence of all power switch tubes according to phase output voltage waveforms.
3. three level carrier modulator approaches of one kind as described in claim 1, it is characterised in that: 2 modulation system of mode specifically:
Firstly, by modulating wave VrxWith two carrier wave V with mutually stackingc1And Vc2It is compared, obtains the phase outputs level signals,
Manner of comparison are as follows:
Work as Vrx> Vc1, three-level current transformer x phase exports positive level；
Work as Vrx< Vc2, three-level current transformer x phase exports negative level；
Work as Vc2< Vrx< Vc1, three-level current transformer x phase exports zero level.
Above-mentioned two carrier wave with mutually stacking is all made of per unit value, Vc1Amplitude range be [0,1], Vc2Amplitude range be [- 1,
0], and:
Vc2=Vc1-1 (2)
Then, the on off sequence of all power switch tubes is obtained according to phase output voltage waveforms.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110336480A (en) * | 2019-07-22 | 2019-10-15 | 中国科学院电工研究所 | A kind of three-level current transformer square-wave frequency modulation method realized based on carrier wave |
| CN114257114A (en) * | 2021-12-11 | 2022-03-29 | 中科华士电气科技南京有限公司 | Three-level converter control method and system based on carrier phase shift modulation |
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| CN114257114A (en) * | 2021-12-11 | 2022-03-29 | 中科华士电气科技南京有限公司 | Three-level converter control method and system based on carrier phase shift modulation |
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