CN109756126A - A method of preventing two level jump of three-level current transformer phase voltage - Google Patents
A method of preventing two level jump of three-level current transformer phase voltage Download PDFInfo
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Abstract
A method of preventing two level jump of three-level current transformer phase voltage.When three-level current transformer is that PWM is laminated in carrier wave reverse phase using modulation strategy, while triangular carrier is laminated in the reverse phase for generating two groups of phase phase difference 180 degrees；By judging the direction of three-phase modulations wave, is chosen when any phase modulating wave direction changes and not will lead to one group of two level jump of phase voltage in two groups of triangular carriers as practical relatively triangular carrier；Using practical relatively triangular carrier and three-phase modulations Bobbi compared with obtaining the switch state of each power device of three-level current transformer.The present invention can prevent two level jump of phase voltage occur under three-level current transformer carrier wave reverse phase stacking PWM, compared to three-level current transformer using the conventional situation of carrier wave reverse phase stacking PWM, improve the safety and reliability of three-level current transformer.
Description
Technical field
The present invention relates to a kind of PWM control methods.
Background technique
Typical three-level current transformer such as three level NPC (Neutral Point Clamped) current transformer, topological structure
As shown in Figure 1.Definition three-level current transformer DC voltage is 2E, passes through the logical of control each device for power switching of three-phase bridge arm
Disconnected, three-level current transformer exchange side phase voltage can export tri- kinds of level states of P, O, N respectively, corresponding voltage value be respectively 2E, E,
0.Compared to two level current transformers, three-level current transformer can reduce the voltage stress that each device for power switching is born, so as to
To promote maximum output voltage, and its harmonic performance is more superior.Based on the above advantage, three-level current transformer is generally answered at present
Speed regulation occasion for mesohigh heavy-duty motor.
Two level jump of phase voltage refers to that three-level current transformer exchange side phase voltage is directly jumped by N level as P level
Or it is directly jumped by P level as N level.For high-power three-level current transformer, Yao Yange is prevented in stable state or dynamic operation mistake
Occurs two level jump of phase voltage in journey, otherwise four series power switch devices simultaneously operation of a phase bridge arm easily causes each device
Part dynamic pressure drop is not equal and damages, and can bring higher dv/dt.For the pulsewidth modulation plan of high-power three-level current transformer
Slightly, it is necessary to two level jump of phase voltage can be prevented.
PWM, that is, POD method (phase-opposite disposition) is laminated in carrier wave reverse phase, is compared based on carrier wave
One kind of SPWM method.For the schematic diagram of POD method as shown in Fig. 2, POD method is identical by two frequencies, phase is identical, amplitude etc. is big
Reversed triangular carrier and three-phase modulations wave are compared the corresponding pwm control signal of generation, thus control three-level current transformer
Each bridge arm device for power switching is switched on or off.POD method principle is simple, it is easy to accomplish, be it is a kind of commonly using pulsewidth tune
System strategy.
POD method relatively generates corresponding pwm control signal, the value of three-phase modulations wave with three-phase modulations Bobbi using triangular carrier
For the sampled value obtained by rule sampling.In the ideal case, the sampling zero point of three-phase modulations wave and the zero point of triangular carrier
It is overlapped, is not in two level jump of phase voltage under POD method effect at this time, as shown in Figure 3.But in practical engineering applications, by
It is zero in not can guarantee three-phase modulations wave initial samples value, it is likely that there are the zero points of modulating wave and the zero point of triangular carrier not to weigh
The case where conjunction, POD method effect at this time is lower it is possible that two level jump of phase voltage, as shown in Figure 4.
Three-level current transformer is likely to occur two level jump of phase voltage under the effect of POD method, reduces three-level current transformer
Safety and reliability, which has limited use of the POD method in high-power three-level current transformer.
Summary of the invention
Two level jump of phase voltage existing for three-level current transformer is applied to lack to overcome conventional carrier reverse phase that PWM method is laminated
It falls into, the present invention proposes a kind of method for preventing two level jump of three-level current transformer phase voltage.The present invention passes through while generating two
Triangular carrier is laminated in the reverse phase of group phase phase difference 180 degree, and in modulating wave direction change selection wherein one group of triangular carrier with
Modulating wave is compared, to prevent two level jump of phase voltage under the stacking PWM effect of carrier wave reverse phase, improves three level
Safety and reliability of the current transformer under the stacking PWM effect of carrier wave reverse phase.
The present invention uses Unsymmetric Regular sample method to the sampling of modulating wave, i.e. sample frequency is triangular carrier frequency
Twice, in the zero point and peak point of triangular carrier, sampling should be carried out.
The present invention is that carrier wave reverse phase generates two groups of phases when PWM is laminated simultaneously in the used modulation strategy of three-level current transformer
Triangular carrier is laminated in the reverse phase for differing 180 degree；By judging the direction of three-phase modulations wave, when any phase modulating wave direction changes
It chooses and not will lead to one group of two level jump of phase voltage in two groups of triangular carriers as practical relatively triangular carrier；Utilize practical ratio
Compared with triangular carrier and three-phase modulations Bobbi compared with the switch state of each power device of three-level current transformer is obtained, prevent three level unsteady flows
There is two level jump of phase voltage under device carrier wave reverse phase stacking PWM.
It is specific as follows:
Three-phase modulations wave of the present invention is defined as follows:
In formula (1), M is modulation ratio, and ω represents angular speed, and having the π of ω=2 f, f is three-phase modulations wave frequency rate.
The specific steps of the present invention are as follows:
1, the triangular carrier of two groups of phase phase difference 180 degrees is generated simultaneously
The present invention generates two groups of triangular carriers simultaneously, and two amplitudes, frequencies are identical up and down for two groups of each freedom of triangular carrier
The stacking of triangular carrier reverse phase is constituted；Wherein, first group of triangular carrier is made of the stacking of Carr1 and Carr2 reverse phase, and definition is such as
Under:
To Carr1 and Carr2 definition in, fcarrRepresent carrier frequency, tcarrCorresponding time variable, tcarrIt is defined as follows:
tcarr=t-S × tcarr (3)
In formula (3), t corresponds to the real time, and S is t to tcarrIntegral multiple；
Second group of triangular carrier is made of the stacking of Carr3 and Carr4 reverse phase, is defined as follows:
2, the sampled value of three-phase modulations wave is updated when triangular carrier direction changes
In the present invention, the sampled value of three-phase modulations wave is only updated when triangular carrier direction changes.Define Carrflagpre
For the direction flag of upper sampling period Triangle ID carrier wave, Carrflag is the direction sign of current sample period Triangle ID carrier wave
Will position, the value rule of Carrflag are as follows:
Work as Carrflagpre！When=Carrflag, the sampled value of three-phase modulations wave is updated.
3, judge whether the direction of three-phase modulations wave changes
The present invention judges whether three-phase modulations wave direction changes by the variation of three-phase modulations wave sampled value.Definition
Vapre, Vbpre and Vcpre were respectively A phase, B phase and C phase modulating wave sampled value in a upper sampling period, Va, Vb and Vc difference
For A phase, B phase and C phase modulating wave sampled value in current sample period, the specific rules whether three-phase modulations wave direction changes are judged
Are as follows:
1) as Vapre<0, Vbpre<0, Vcpre>0, Va>0, corresponding A phase direction is by bearing just；
2) work as Vapre>0, Vbpre>0, Vcpre<0, Va<0, corresponding A phase direction is by just to negative；
3) work as Vapre>0, Vbpre<0, Vcpre<0, Vb>0, corresponding B phase direction is by bearing just；
4) as Vapre<0, Vbpre>0, Vcpre>0, Vb<0, corresponding B phase direction is by just to negative；
5) as Vapre<0, Vbpre>0, Vcpre<0, Vc>0, corresponding C phase direction is by bearing just；
6) work as Vapre>0, Vbpre<0, Vcpre>0, Vc<0, corresponding C phase direction is by just to negative.
4, when three-phase modulations wave direction changes, practical relatively triangular carrier is selected from two groups of triangular carriers
The present invention chooses when any phase modulating wave direction changes not will lead to two level of phase voltage in two groups of triangular carriers
That group of jump is practical relatively triangular carrier, the specific selection rule of practical relatively triangular carrier are as follows:
When any phase modulating wave direction changes, if Carrflag=0, first group of triangular carrier Carr1 and Carr2 are selected
For practical relatively triangular carrier；If Carrflag=1, select second group of triangular carrier Carr3 and Carr4 for practical relatively triangle
Carrier wave.
5, practical relatively triangular carrier obtains pwm signal compared with three-phase modulations wave sampled value
The present invention is compared to obtain each power of three-level current transformer with three-phase modulations wave by practical relatively triangular carrier
The switch state of device, specific comparison rule are as follows:
1) when actually relatively triangular carrier is first group of triangular carrier Carr1 and Carr2, when three-phase modulations wave sampled value is big
In Carr1 and Carr2, corresponding modulating wave mutually exports P level；When three-phase modulations wave sampled value be greater than Carr2 and be less than Carr1,
Corresponding modulating wave mutually exports O level；When three-phase modulations wave sampled value is less than Carr1 and Carr2, corresponding modulating wave mutually exports N electricity
It is flat；
2) when actually relatively triangular carrier is second group of triangular carrier Carr3 and Carr4, when three-phase modulations wave sampled value is big
In Carr3 and Carr4, corresponding modulating wave mutually exports P level；When three-phase modulations wave sampled value be greater than Carr4 and be less than Carr3,
Corresponding modulating wave mutually exports O level；When three-phase modulations wave sampled value is less than Carr3 and Carr4, corresponding modulating wave mutually exports N electricity
It is flat.
Detailed description of the invention
Tri- level NPC converter topology figure of Fig. 1；
PWM method schematic diagram is laminated in Fig. 2 carrier wave reverse phase；
Fig. 3 carrier wave reverse phase stacking PWM method effect modulated wave sampling zero point is overlapped with triangular carrier zero point, no phase voltage two
Level jump；
Fig. 4 carrier wave reverse phase stacking PWM method effect modulated wave sampling zero point is not overlapped with triangular carrier zero point, mutually electricity occurs
Press two level jumps；
Waveform of Fig. 5 three phase sine modulating wave within a primitive period；
Fig. 6 carrier wave reverse phase is laminated PWM method and acts on lower 0 degree of phase angle modulating wave sampling zero point situation, in which: Fig. 6 a corresponds to nothing
There is two level jump situation of phase voltage in two level jump situation of phase voltage, Fig. 6 b correspondence；
Fig. 7 carrier wave reverse phase is laminated PWM method and acts on lower 180 degree phase angle modulating wave sampling zero point situation, in which: Fig. 7 a is corresponding
Without two level jump situation of phase voltage, there is two level jump situation of phase voltage in Fig. 7 b correspondence；
The specific implementation flow chart of Fig. 8 the method for the present invention；
Fig. 9 is that PWM method is laminated in modulating wave sampling zero point and triangular carrier zero point weight in conventional carrier reverse phase in embodiment
It closes, the phase voltage Vao, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua under triangular carrier frequency 600Hz；
Figure 10 be in embodiment conventional carrier reverse phase stacking PWM method modulating wave sampling zero point and triangular carrier zero point not
It is overlapped, phase voltage Vao, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua under triangular carrier frequency 600Hz；
Figure 11 is that the method for the present invention is not overlapped in modulating wave sampling zero point with triangular carrier zero point in embodiment, triangular carrier
Phase voltage Vao under frequency 600Hz, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua；
Figure 12 be in embodiment conventional carrier reverse phase stacking PWM method modulating wave sampling zero point and triangular carrier zero point not
It is overlapped, phase voltage Vao, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua under triangular carrier frequency 750Hz；
Figure 13 is that the method for the present invention is not overlapped in modulating wave sampling zero point with triangular carrier zero point in embodiment, triangular carrier
Phase voltage Vao under frequency 750Hz, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua.
Specific embodiment
Present invention will be further explained below with reference to the attached drawings and specific embodiments.
The present invention is that carrier wave reverse phase generates two groups of phases when PWM is laminated simultaneously in the used modulation strategy of three-level current transformer
Triangular carrier is laminated in the reverse phase for differing 180 degree；By judging the direction of three-phase modulations wave, when any phase modulating wave direction changes
It chooses and not will lead to one group of two level jump of phase voltage in two groups of triangular carriers as practical relatively triangular carrier；Utilize practical ratio
Compared with triangular carrier and three-phase modulations Bobbi compared with the switch state of each power device of three-level current transformer is obtained, prevent three level unsteady flows
There is two level jump of phase voltage under device carrier wave reverse phase stacking PWM.
The specific steps of the present invention are as follows:
1, the triangular carrier of two groups of phase phase difference 180 degrees is generated simultaneously
Conventional carrier reverse phase stacking PWM only produces one group of triangular carrier, and the present invention is prevention two level jump of phase voltage, together
The triangular carrier of two groups of phase phase difference 180 degrees of Shi Shengcheng.
2, the sampled value of three-phase modulations wave is updated when triangular carrier direction changes
The present invention obtains the switch of each power device compared with triangular carrier is laminated in reverse phase using three-phase modulations wave sampled value
The sampled value of state, three-phase modulations wave is only updated when triangular carrier direction changes.
3, judge whether the direction of three-phase modulations wave changes
To prevent two level jump of phase voltage, the present invention need to detect whether three-phase modulations wave direction changes.Three-phase tune
Only the direction when 0 spends zero point and 180 degree zero crossing changes wave processed, and Fig. 5 gives three phase sine modulating wave in a base
Waveform in wave period.A phase, B phase and C phase modulating wave in Vapre, Vbpre and Vcpre respectively upper sampling period was defined to adopt
Sample value, Va, Vb and Vc are respectively A phase in current sample period, B phase and C phase modulating wave sampled value.Fig. 5 is observed, for 0 degree of A phase
Phase angle, as Vapre<0, Vbpre<0, Vcpre>0, Va>0, Vb<0, when Vc>0, corresponding A phase modulating wave direction is by bearing just；
For A phase 180 degree phase angle, work as Vapre>0, Vbpre>0, Vcpre<0, Va<0, Vb>0, when Vc<0, corresponding A phase modulating wave side
Xiang Youzheng is to negative；For 0 degree of phase angle of B phase, work as Vapre>0, Vbpre<0, Vcpre<0, Vb>0, Va>0, when Vc<0, corresponding B
Phase modulating wave direction is by bearing just；For B phase 180 degree phase angle, as Vapre<0, Vbpre>0, Vcpre>0, Vb<0, Va<0,
When Vc > 0, corresponding B phase modulating wave direction is by just to negative；For 0 degree of phase angle of C phase, as Vapre<0, Vbpre>0, Vcpre<0,
When Vc>0, Va<0, Vb>0, corresponding C phase modulating wave direction is by bearing just；For C phase 180 degree phase angle, work as Vapre > 0, Vbpre
When<0, Vcpre>0, Vc<0, Va>0, Vb<0, corresponding C phase modulating wave direction is by just to negative.
4, when three-phase modulations wave direction changes, practical relatively triangular carrier is selected from two groups of triangular carriers
The present invention chooses when any phase modulating wave direction changes not will lead to two level of phase voltage in two groups of triangular carriers
That group of jump is practical relatively triangular carrier.Correctly to select practical comparison triangular carrier, the side PWM is laminated to carrier wave reverse phase
The case where two level jump of phase voltage will not be generated under method effect, is analyzed.
PWM method is laminated for carrier wave reverse phase, when modulating wave zero point is not overlapped and modulating wave 0 spends zero with carrier wave zero point
Triangular carrier under the nearest positive sampled value of point corresponds to upper triangular carrier failing edge, or negative sampled value is corresponding recently in 180 degree zero crossing
Rising edge will not generate two level jump of phase voltage.
Spending zero point to 0, the corresponding upper triangular carrier failing edge of positive sampled value will not generate phase voltage two level jumps original recently
Because being analyzed as follows:
As shown in Figure 4, when modulating wave sampling zero point is not overlapped with triangular carrier zero point, three-level current transformer is anti-in carrier wave
Mutually may occur two level jump of phase voltage at 0 degree of phase angle under stacking PWM effect.Carrier wave reverse phase stacking PWM method is made
The possible modulating wave sampling situations in 0 degree of phase angle place are divided when not being overlapped with modulated wave sampling zero point with carrier wave zero point
Analysis, is summarized in Fig. 6.It will be appreciated from fig. 6 that spend zero point 0 when modulating wave samples the corresponding upper triangular carrier rising edge of positive value, meeting recently
Lead to occur two level jump of phase voltage at 0 degree；Zero point, which is spent, 0 when modulating wave samples the corresponding upper triangular carrier of positive value recently
Failing edge will not generate two level jump of phase voltage.
To 180 degree zero crossing, the corresponding lower triangular carrier rising edge of negative sampled value will not generate two level jump of phase voltage recently
The analysis of causes is as follows:
As shown in Figure 4, when modulating wave sampling zero point is not overlapped with triangular carrier zero point, three-level current transformer is anti-in carrier wave
Mutually may occur two level jump of phase voltage at 180 degree phase angle under the effect of stacking PWM method.PWM is laminated to carrier wave reverse phase
The possible modulating wave sampling feelings in 180 degree phase angle place when method effect modulated wave sampling zero point is not overlapped with carrier wave zero point
Condition is analyzed, and Fig. 7 is summarized in.As shown in Figure 7, it is carried when modulating wave samples the corresponding upper triangle of positive value in 180 degree zero crossing recently
Wave failing edge will lead at 180 degree and two level jump of phase voltage occurs；It is born when modulating wave samples recently in 180 degree zero crossing
The corresponding lower triangular carrier rising edge of value, will not generate two level jump of phase voltage.
According to the above analysis, by detection 0 degree of phase angle of three-phase modulations wave recently at positive sampled value and 180 degree phase angle
Nearest negative sampled value, then selects the triangular carrier of respective direction to be compared, three-level current transformer can be made anti-in carrier wave
Mutually two level jump of phase voltage will not be generated under the effect of stacking PWM method.
Convolution (2), formula (3) and (5), for first group of triangular carrier Carr1 and Carr2, as Carrflag=0,
Carr1 corresponds to the upper triangular carrier in failing edge direction, and Carr2 corresponds to the lower triangular carrier in rising edge direction；When
When Carrflag=1, Carr1 corresponds to the upper triangular carrier in rising edge direction, and Carr2 corresponds to the lower triangle in failing edge direction
Carrier wave.
Convolution (3), formula (4) and (5), for second group of triangular carrier Carr3 and Carr4, as Carrflag=0,
Carr3 corresponds to the upper triangular carrier in rising edge direction, and Carr4 corresponds to the lower triangular carrier in failing edge direction；When
When Carrflag=1, Carr3 corresponds to the upper triangular carrier in failing edge direction, and Carr4 corresponds to the lower triangle in rising edge direction
Carrier wave.
Detect at 0 degree phase angle of three-phase modulations wave at positive sampled value and 180 degree phase angle recently that negative sampled value is inspection recently
It surveys whether three-phase modulations wave direction changes, corresponds to 0 degree or 180 degree phase angle.If Carrflag=0 at this time, selection the
One group of triangular carrier Carr1 and Carr2 are that practical relatively triangular carrier, Carr1 correspond to the upper triangular carrier in failing edge direction,
Carr2 corresponds to the lower triangular carrier in rising edge direction, then is compared using Carr1 and Carr2 and three-phase modulations wave sampled value
Less likely generate two level jump of phase voltage；If Carrflag=1, it is practical for selecting second group of triangular carrier Carr3 and Carr4
Compare triangular carrier, Carr3 corresponds to the upper triangular carrier in failing edge direction, and Carr4 corresponds to the lower triangle in rising edge direction
Carrier wave, then two level jump of phase voltage will not be generated by being compared using Carr3 and Carr4 with three-phase modulations wave sampled value.
5, practical relatively triangular carrier obtains pwm signal compared with three-phase modulations wave sampled value
The comparison rule for formulating practical relatively triangular carrier and three-phase modulations wave, according to comparison rule to practical relatively triangle
Carrier wave is compared with three-phase modulations wave, obtains the switch state of each power device of three-level current transformer, thus in carrier wave reverse phase
Two level jump of phase voltage is prevented under stacking PWM method effect.
Implementing procedure of the present invention is as shown in Figure 8.
The present invention passes through while generating the reverse phase stacking triangular carrier of two groups of phase phase difference 180 degrees, and in modulating wave direction
That group triangular carrier that selection not will lead to two level jump of phase voltage when variation is compared with modulating wave, thus in carrier wave
Two level jump of phase voltage is prevented under reverse phase stacking PWM method effect, overcomes the stacking PWM method application of conventional carrier reverse phase
The defect existing for three-level current transformer improves safety of the three-level current transformer under the stacking PWM method effect of carrier wave reverse phase
Property and reliability.
The embodiment of the present invention builds three level NPC inverter models by PSIM software, this hair is respectively adopted in modulation strategy
PWM method is laminated in the two level jump method of prevention phase voltage and conventional carrier reverse phase of bright proposition, utilizes the simulating, verifying present invention
The validity of the prevention two level jump method of three-level current transformer phase voltage of proposition.Simulated conditions such as table 1.
1 embodiment emulation experiment condition of table
Fig. 9 is that PWM method is laminated in modulating wave sampling zero point and triangular carrier zero point weight in conventional carrier reverse phase in embodiment
It closes, the phase voltage Vao, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua under triangular carrier frequency 600Hz.By
Fig. 9 knows, when modulating wave sampling zero point is overlapped with triangular carrier zero point, conventional carrier reverse phase is laminated will not under PWM method effect
There is two level jump of phase voltage.
Figure 10 is laminated PWM method for conventional carrier reverse phase in embodiment and samples zero point and triangular carrier zero point not in modulating wave
It is overlapped, the phase voltage Vao, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua under triangular carrier frequency 600Hz.
Known by Figure 10, under even carriers ratio, when modulating wave sampling zero point is not overlapped with triangular carrier zero point, the stacking of conventional carrier reverse phase
Two level jump of phase voltage may occur at 0 degree and 180 degree phase angle under PWM method effect, be unfavorable for three level unsteady flows
The safe operation of device.
Figure 11 is that the present invention is not overlapped in modulating wave sampling zero point with triangular carrier zero point in embodiment, triangular carrier frequency
Phase voltage Vao under 600Hz, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua.Comparison diagram 10 and Figure 11 can
Know, under even carriers ratio, when modulating wave sampling zero point is not overlapped with triangular carrier zero point, the present invention can effectively prevent carrier wave
Two level jump of phase voltage being likely to occur under reverse phase stacking PWM method effect.
Figure 12 is laminated PWM method for conventional carrier reverse phase in embodiment and samples zero point and triangular carrier zero point not in modulating wave
It is overlapped, the phase voltage Vao, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua under triangular carrier frequency 750Hz.
Known by Figure 12, under odd carriers ratio, when modulating wave sampling zero point is not overlapped with triangular carrier zero point, the stacking of conventional carrier reverse phase
Two level jump of phase voltage may occur at 0 degree and 180 degree phase angle under PWM method effect, be unfavorable for three level unsteady flows
The safe operation of device.
Figure 13 is that the method for the present invention is not overlapped in modulating wave sampling zero point with triangular carrier zero point in embodiment, triangular carrier
Phase voltage Vao under frequency 750Hz, triangular carrier Vcarr1, Vcarr2 and A phase modulating wave sampled value Ua.Comparison diagram 12 and figure
13 it is found that, when modulating wave sampling zero point is not overlapped with triangular carrier zero point, the method for the present invention can be effective under odd carriers ratio
Prevent two level jump of phase voltage being likely to occur under the stacking PWM method effect of carrier wave reverse phase.
As shown in Fig. 9~Figure 13, the result verification of embodiment two level of prevention three-level current transformer phase voltage of the invention
The validity of jump method.When modulating wave sampling zero point is not overlapped with triangular carrier zero point, under any carrier wave ratio, the present invention
Method can make three-level current transformer not occur two level jump of phase voltage under the stacking PWM method effect of carrier wave reverse phase,
Improve safety and reliability of the three-level current transformer under the stacking PWM method effect of carrier wave reverse phase.
Claims (8)
1. a kind of method for preventing two level jump of three-level current transformer phase voltage, which is characterized in that when three-level current transformer makes
When with modulation strategy being carrier wave reverse phase stacking PWM, while triangular carrier is laminated in the reverse phase for generating two groups of phase phase difference 180 degrees；It is logical
The direction for judging three-phase modulations wave is crossed, is chosen when any phase modulating wave direction changes and not will lead to mutually electricity in two groups of triangular carriers
One group of two level jumps is pressed to compare triangular carrier to be practical；It is relatively obtained using practical relatively triangular carrier with three-phase modulations Bobbi
The switch state of each power device of three-level current transformer, prevention three-level current transformer carrier wave reverse phase, which is laminated under PWM, there is phase voltage
Two level jumps.
2. the method for prevention two level jump of three-level current transformer phase voltage according to claim 1, which is characterized in that fixed
Adopted three-level current transformer DC voltage is 2E, and two level jump of phase voltage refers to that phase voltage level is directly become by 2E
Directly become 2E for 0 or from 0.
3. the method for three preventions, two level jump of level current transformer phase voltage according to claim 1, which is characterized in that institute
The identical triangular carrier reverse phase stacking of two amplitudes, frequency up and down of each freedom of triangular carrier for the two groups of phase phase difference 180 degrees stated
It constitutes；Wherein, first group of triangular carrier is made of the stacking of Carr1 and Carr2 reverse phase, is defined as follows:
To Carr1 and Carr2 definition in, fcarrRepresent carrier frequency, tcarrCorresponding time variable, tcarrIt is defined as follows:
tcarr=t-S × tcarr
To tcarrIn definition, t corresponds to the real time, and S is t to tcarrIntegral multiple；
Second group of triangular carrier is made of the stacking of Carr3 and Carr4 reverse phase, is defined as follows:
4. the method for prevention two level jump of three-level current transformer phase voltage according to claim 1, which is characterized in that institute
The three-phase modulations wave stated is defined as follows:
In above formula, M is modulation ratio, and ω represents angular speed, and having the π of ω=2 f, f is three-phase modulations wave frequency rate.
5. the method for prevention two level jump of three-level current transformer phase voltage according to claim 1, which is characterized in that institute
The method stated judges whether three-phase modulations wave direction changes by the variation of three-phase modulations wave sampled value；Definition Vapre,
Vbpre and Vcpre was respectively A phase, B phase and C phase modulating wave sampled value in a upper sampling period, and Va, Vb and Vc are respectively current
A phase, B phase and C phase modulating wave sampled value, judge the specific rules whether three-phase modulations wave direction changes in sampling period are as follows:
1) as Vapre<0, Vbpre<0, Vcpre>0, Va>0, corresponding A phase direction is by bearing just；
2) work as Vapre>0, Vbpre>0, Vcpre<0, Va<0, corresponding A phase direction is by just to negative；
3) work as Vapre>0, Vbpre<0, Vcpre<0, Vb>0, corresponding B phase direction is by bearing just；
4) as Vapre<0, Vbpre>0, Vcpre>0, Vb<0, corresponding B phase direction is by just to negative；
5) as Vapre<0, Vbpre>0, Vcpre<0, Vc>0, corresponding C phase direction is by bearing just；
6) work as Vapre>0, Vbpre<0, Vcpre>0, Vc<0, corresponding C phase direction is by just to negative.
6. the method for prevention two level jump of three-level current transformer phase voltage according to claim 5, which is characterized in that institute
The only update when triangular carrier direction changes of the sampled value for the three-phase modulations wave stated；Defining Carrflagpre was upper sampling week
The direction flag of phase Triangle ID carrier wave, Carrflag are the direction flag of current sample period Triangle ID carrier wave, are had:
Work as Carrflagpre！When=Carrflag, the sampled value of three-phase modulations wave is updated.
7. the method for prevention two level jump of three-level current transformer phase voltage according to claim 1, which is characterized in that
It is real that any phase modulating wave direction, which is chosen when changing and not will lead to that group of two level jump of phase voltage in two groups of triangular carriers,
Compare triangular carrier, the specific selection rule of practical relatively triangular carrier in border are as follows:
When any phase modulating wave direction changes, if Carrflag=0, it is real for selecting first group of triangular carrier Carr1 and Carr2
Compare triangular carrier in border；If Carrflag=1, second group of triangular carrier Carr3 and Carr4 is selected to carry for practical relatively triangle
Wave.
8. the method for prevention two level jump of three-level current transformer phase voltage according to claim 1, which is characterized in that logical
It crosses practical comparison triangular carrier to be compared with three-phase modulations wave, obtains the switch state of each power device of three-level current transformer,
Specific comparison rule are as follows:
1) when actually relatively triangular carrier is first group of triangular carrier Carr1 and Carr2, when three-phase modulations wave sampled value is greater than
Carr1 and Carr2, corresponding modulating wave phase output level are 2E；When three-phase modulations wave sampled value be greater than Carr2 and be less than Carr1,
Corresponding modulating wave phase output level is E；When three-phase modulations wave sampled value is less than Carr1 and Carr2, corresponding modulating wave mutually exports electricity
Put down is 0；
2) when actually relatively triangular carrier is second group of triangular carrier Carr3 and Carr4, when three-phase modulations wave sampled value is greater than
Carr3 and Carr4, corresponding modulating wave phase output level are 2E；When three-phase modulations wave sampled value be greater than Carr4 and be less than Carr3,
Corresponding modulating wave phase output level is E；When three-phase modulations wave sampled value is less than Carr3 and Carr4, corresponding modulating wave mutually exports electricity
Put down is 0.
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| CN201910058434.XA CN109756126B (en) | 2019-01-22 | 2019-01-22 | Method for preventing two-level jump of phase voltage of three-level converter |
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| CN111082688A (en) * | 2019-12-25 | 2020-04-28 | 中国科学院电工研究所 | Carrier reverse phase laminated PWM midpoint potential balance control method |
| EP3846333A1 (en) * | 2019-12-30 | 2021-07-07 | General Electric Company | Carrier-based pulse width modulation control for back-to-back voltage source converters |
| 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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| CN106301054A (en) * | 2016-08-31 | 2017-01-04 | 西安电子科技大学 | A kind of modified model POD modulation strategy of cascaded H-bridges photovoltaic DC-to-AC converter |
| CN108282104A (en) * | 2017-01-06 | 2018-07-13 | 南京航空航天大学 | A kind of modulation and voltage stabilizing control method suitable for single supply binary system Mixed cascading H bridge multi-electrical level inverters |
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| CN106301054A (en) * | 2016-08-31 | 2017-01-04 | 西安电子科技大学 | A kind of modified model POD modulation strategy of cascaded H-bridges photovoltaic DC-to-AC converter |
| CN108282104A (en) * | 2017-01-06 | 2018-07-13 | 南京航空航天大学 | A kind of modulation and voltage stabilizing control method suitable for single supply binary system Mixed cascading H bridge multi-electrical level inverters |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111082688A (en) * | 2019-12-25 | 2020-04-28 | 中国科学院电工研究所 | Carrier reverse phase laminated PWM midpoint potential balance control method |
| CN111082688B (en) * | 2019-12-25 | 2020-10-30 | 中国科学院电工研究所 | Carrier reverse phase laminated PWM midpoint potential balance control method |
| EP3846333A1 (en) * | 2019-12-30 | 2021-07-07 | General Electric Company | Carrier-based pulse width modulation control for back-to-back voltage source converters |
| US11296612B2 (en) | 2019-12-30 | 2022-04-05 | General Electric Company | Carrier-based pulse width modulation control for back-to-back voltage source converters |
| 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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