CN106385191B - The three level mid-point voltage control methods based on unified discontinuous modula tion strategy - Google Patents
The three level mid-point voltage control methods based on unified discontinuous modula tion strategy Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
- H02M7/487—Neutral point clamped inverters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0048—Circuits or arrangements for reducing losses
- H02M1/0054—Transistor switching losses
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The invention discloses a kind of three level mid-point voltage control methods based on unified discontinuous modula tion strategy, first according to the exchange side voltage of sensor acquisition, ac-side current, DC side total voltage, DC side positive pole line voltage, DC side negative busbar voltage data, then positive and negative small vector action time scale factor k is calculated, mid-point voltage control is finally carried out to inverter using unified discontinuous modula tion strategy；BANGBANG control strategy is combined in the present invention, so that unified discontinuous modula tion strategy is had the ability of homeostasis midpoint potential, and reduce the loss of switch.
Description
Technical field
The invention belongs to power electronics fields, more specifically, are related to a kind of based on unified discontinuous modula tion plan
Three level mid-point voltage control methods slightly.
Background technique
In recent years, three-level inverter has obtained quick development, and discrete pulse width (DPWM) modulation can be mentioned because of it
High inverter efficiency has obtained good application in two-level inverter.But in three-level inverter, because its output can
It is clamped to positive bus-bar, negative busbar and neutral point, causes its midpoint potential that cannot balance.This problem has caused both at home and abroad
The extensive concern of scholar.It the use of unified discontinuous modula tion strategy is to improve the unbalanced important channel in midpoint.
There are many researchs about neutral point potential balance method: 1) independent DC power supply method；However since it is desired that increase
The quantity of DC source, application range are limited.2) external neutral balance control circuit method；This method can make three level
Inverter hardware cost is significantly increased.3) method of neutral point of electric network；This method is only limitted to use in three-phase four-wire system.
4) modulation control method；This method not will increase the cost of inverter, but its essence is the work for changing common-mode voltage or middle vector
With the time, and middle vector is to cause the unbalanced major reason in midpoint, and when common-mode voltage is added in DPWM, DPWM is also just lost
Reduce the advantage of loss.
Summary of the invention
It is an object of the invention to overcome the deficiencies of the prior art and provide a kind of three based on unified discontinuous modula tion strategy
Level mid-point voltage control method adjusts the positive and negative small vector action time of unified discontinuous modula tion by BANGBANG control
Scale factor, then pwm signal is generated using double triangular carrier comparative approach, it can be very good balance mid-point voltage, reduce switch
Loss.
For achieving the above object, a kind of three level mid-point voltage controls based on unified discontinuous modula tion strategy of the present invention
Method processed, which comprises the following steps:
(1), exchange side voltage U is obtained by voltage-current sensorx(x=a, b, c), ac-side current ix(x=a, b,
C), DC side total voltage Udc, DC side positive pole line voltage UP, DC side negative busbar voltage UN；
(2), in conjunction with ac-side current ix, exchange side voltage UxThree-phase voltage, which is obtained, by voltage, current control controls signal
ux(x=a, b, c)；
(2.1), to ac-side current ix, exchange side voltage UxIt transforms on two-phase synchronous rotating frame (d, q), it is public
Formula is as follows:
Wherein, θ is the rotation angle of synchronously rotating reference frame q axis；
(2.2), two-phase voltage control signal u is obtained using PI control methodq、ud, governing equation is as follows:
Wherein, KiP、KiLFor proportion adjustment gain and integral adjustment gain,For current instruction value, L is filter electricity
Inductance value；
(2.3), two-phase voltage obtained in step (2.2) is controlled into signal uq、udIt is converted into three-phase voltage control signal
ux, formula are as follows:
(3), in conjunction with DC side positive pole line voltage UP, negative busbar voltage UN, three-phase voltage control signal uxAnd exchange side electricity
Flow ix, positive and negative small vector action time scale factor k is calculated using BANGBANG control method；
(4), signal u is controlled in conjunction with three-phase voltagex, DC side total voltage Udc, positive and negative small vector action time scale factor k
Using unified discontinuous modula tion strategy, calculate based on the equivalent modulating wave u under double carried-based PWMsmx(x=a, b, c)；
(5), in conjunction with equivalent modulating wave umx, the driving signal of IGBT is generated using double triangular carrier comparative approach；
(5.1), compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxGreater than positive triangle
When carrier wave, the pwm signal of the corresponding IGBT of x under the state is exported；
(5.2), compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxGreater than positive triangle
When carrier wave is less than negative triangular carrier, the pwm signal of the corresponding IGBT of x under the state is exported；
(5.3), compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxLess than negative triangle
When carrier wave, the pwm signal of the corresponding IGBT of x under the state is exported.
Wherein, in the step (3), using BANGBANG control method calculate positive and negative small vector action time ratio because
The method of sub- k are as follows:
(2.1), DC bus unbalance of neutral-point voltage amount Δ U is determinedC:
ΔUC=UN-UP
Wherein, UP、UNRespectively indicate the positive and negative busbar voltage of DC side；
(2.2), by voltage deviation Δ UCWith preset mid-point voltage difference threshold value UdzCompare, if voltage deviation Δ UC
In threshold value UdzWithin, then keep k value constant；If voltage deviation Δ UCMore than threshold value UdzWhen, change k using following methods
Value；
(2.2.1), the value for calculating k', formula are as follows:
K'=sign (Δ UC×ux×ix)
Wherein, function sign (Y) are as follows:
Wherein, the determination method of x are as follows:
Work as ua>0,ub<0,ucWhen < 0, x=a；
Work as ua>0,ub>0,ucWhen < 0, x=c；
Work as ua<0,ub>0,ucWhen < 0, x=b；
Work as ua<0,ub>0,ucWhen > 0, x=a；
Work as ua<0,ub<0,ucWhen > 0, x=c；
Work as ua>0,ub<0,ucWhen > 0, x=b；
(2.2.2), the value for judging k', as k'=0, k is remained unchanged；As k' ≠ 0, k=k'.
Further, the mid-point voltage difference threshold value UdzValue are as follows:
(3.1), U is takendzIn DC side total voltage Udc1% within, it may be assumed that Udz1% × U of <dc；
(3.2)、UzdWith midpoint electric current imMaximum value im-maxWith the period of change T of kkMinimum value Tk-minRelationship such as
Under:
Wherein, CP、CNRespectively indicate the size of DC bus capacitor；In order to reduce switching loss, the period of change T of kkIt is remote
Greater than the control cycle T of controllers, i.e. Tk> > Ts, then Tk-min> > Ts；im-maxWhen obtaining maximum value, expression formula is
im-max=m × Im, wherein m is modulation ratio, ImFor ac-side current ixAmplitude；
(3.3), U is obtained according to step (3.1) and (3.2)dzValue range are as follows:
Wherein, in the step (4), the method for the unified equivalent modulating wave of discontinuous modula tion policy calculation is utilized are as follows:
(4.1), the modulation ratio that m is three-level inverter is defined, expression formula isThen three-phase electricity is voltage-controlled
Signal u processedx(x=a, b, c) can be indicated are as follows:
(4.2), signal u is controlled to the three-phase voltage in above formulaxThe third-harmonic component injection of first time is carried out, for the first time
The third-harmonic component of injection are as follows:
uz1=-0.5 × MAX (ua,ub,uc)-0.5×MIN(ua,ub,uc)
Wherein, MAX is maximizing operator, and MIN is operator of minimizing；Use uaz、ubzAnd uczIndicate injection uz1Afterwards
Three-phase voltage control signal, expression formula are as follows:
(4.3), the linearisation that above formula is shown below:
Wherein,For the u after linear transformationxz(x=a, b, c), MOD are complementation operation；
(4.4), signal u is controlled to the three-phase voltage in above formulaxSecondary third-harmonic component injection is carried out, second
The third-harmonic component of injection are as follows:
(4.5), three-phase voltage is controlled into signal ux, and the third-harmonic component u of injection for the first timez1It is injected with second
Third-harmonic component uz2It is corresponding mutually sum, obtain the equivalent modulating wave u of unified discontinuous modula tion strategyma、umbAnd umc；
Goal of the invention of the invention is achieved in that
A kind of three level mid-point voltage control methods based on unified discontinuous modula tion strategy of the present invention, first according to sensor
Exchange side voltage, ac-side current, DC side total voltage, DC side positive pole line voltage, the DC side negative busbar voltage number of acquisition
According to, then calculate positive and negative small vector action time scale factor k, finally using unified discontinuous modula tion strategy to inverter into
The control of row mid-point voltage；BANGBANG control strategy is combined in the present invention, and unified discontinuous modula tion strategy is made to have self flat
The ability of weighing apparatus midpoint potential, and reduce the loss of switch.
Detailed description of the invention
Fig. 1 is that the present invention is based on three level mid-point voltage control block diagrams of unified discontinuous modula tion strategy；
Fig. 2 is to calculate positive and negative small vector action time scale factor k flow chart；
Fig. 3 is unified discontinuous modula tion policy control block diagram；
Fig. 4 modulation ratio 0.8, simulation result diagram at 0 ° of power-factor angle；
Fig. 5 modulation ratio 0.4, simulation result diagram at 30 ° of power-factor angle；
Fig. 6 modulation ratio 0.8, experimental result picture at 0 ° of power-factor angle；
Fig. 7 modulation ratio 0.4, experimental result picture at 30 ° of power-factor angle.
Specific embodiment
A specific embodiment of the invention is described with reference to the accompanying drawing, preferably so as to those skilled in the art
Understand the present invention.Requiring particular attention is that in the following description, when known function and the detailed description of design perhaps
When can desalinate main contents of the invention, these descriptions will be ignored herein.
Embodiment
For the convenience of description, being first illustrated to the relevant speciality term occurred in specific embodiment:
BANGBANG: bang-bang control；
PWM (Pulse Width Modulation): pulse width modulation；
IGBT (Insulated Gate Bipolar Transistor), insulated gate bipolar transistor.
Fig. 1 is that the present invention is based on three level mid-point voltage control block diagrams of unified discontinuous modula tion strategy.
In the present embodiment, in conjunction with the three level mid-point voltage controls as shown in Figure 1 based on unified discontinuous modula tion strategy
The control method of three level mid-point voltages is described in detail in block diagram processed, specifically includes the following steps:
S1, exchange side voltage U is obtained by voltage-current sensorx(x=a, b, c), ac-side current ix(x=a, b,
C), DC side total voltage Udc, DC side positive pole line voltage UP, DC side negative busbar voltage UNReal time data.
S2, in conjunction with ac-side current ix, exchange side voltage UxThree-phase voltage, which is obtained, by voltage, current control controls signal
ux(x=a, b, c)；
S2.1, to ac-side current ix, exchange side voltage UxIt transforms on two-phase synchronous rotating frame (d, q), formula
It is as follows:
Wherein, θ is the rotation angle of synchronously rotating reference frame q axis；
S2.2, two-phase voltage control signal u is obtained using PI control methodq、ud, governing equation is as follows:
In the present embodiment, proportion adjustment gain KiP=0.8, integral adjustment gain KiI=10；Current instruction value is as needed
Current on line side size and power factor determine, such as in ac-side current be 10A, at 30 ° of power factor, current-order isThe LCL filter inductance value L=1.4mH of selection；
S2.3, two-phase voltage obtained in step S2.2 is controlled into signal uq、udIt is converted into three-phase voltage control signal ux,
Its formula are as follows:
S3, in conjunction with DC side positive pole line voltage UP, negative busbar voltage UN, and exchange side voltage Ux, ac-side current ix,
Positive and negative small vector action time scale factor k is calculated using BANGBANG control method；
Wherein, as shown in Fig. 2, calculating positive and negative small vector action time scale factor k's using BANGBANG control method
Method are as follows:
S3.1, DC bus unbalance of neutral-point voltage amount Δ U is determinedC:
ΔUC=UN-UP
Wherein, UP、UNRespectively indicate the positive and negative busbar voltage of DC side；
S3.2, by voltage deviation Δ UCWith preset mid-point voltage difference threshold value UdzCompare, if voltage deviation Δ UC
In threshold value UdzWithin, then keep k value constant；If voltage deviation Δ UCMore than threshold value UdzWhen, change k using following methods
Value；
S3.2.1, the value for calculating k', formula are as follows:
K'=sign (Δ UC×ux×ix)
Wherein, function sign (Y) are as follows:
Wherein, according to the u acquired in real timex, following table is inquired, determines that x's takes phase:
| Voltage relationship | x |
| ua>0,ub<0,uc<0 | a |
| ua>0,ub>0,uc<0 | c |
| ua<0,ub>0,uc<0 | b |
| ua<0,ub>0,uc>0 | a |
| ua<0,ub<0,uc>0 | c |
| ua>0,ub<0,uc>0 | b |
The value for so obtaining k' is respectively 1,0, -1；
For example, working as ua=138.6V, ub=-69.3V, uc=-69.3V, ia=8A, ib=-4A, ic=-4A, Δ UC=-
When 5V, then x takes a phase, at this point, k'=-1.
S3.2.2, the value for judging k', as k'=0, k is remained unchanged；As k' ≠ 0, k=k'.For example, working as k'=-1
When, k=-1.
Wherein, mid-point voltage difference threshold value UdzValue are as follows:
1) U, is takendzIn DC side total voltage Udc1% within, it may be assumed that Udz1% × U of <dc；In the present embodiment, 1% is root
The empirical value obtained according to many experiments, specific value can also be accepted or rejected according to experimental situation；
2)、UzdWith midpoint electric current imMaximum value im-maxWith the period of change T of kkMinimum value Tk-minRelationship it is as follows:
Wherein, CP、CNRespectively indicate the size of DC bus capacitor；In order to reduce inverter switching device loss, the period of change of k
TkThe significantly larger than control cycle T of controllers, i.e. Tk> > Ts, it will be appreciated that Tk-min> > Ts；im-maxWhen obtaining maximum value,
Expression formula is im-max=m × Im, wherein m is modulation ratio, ImFor ac-side current ixAmplitude；
3), according to step 1) and 2) obtaining UdzValue range are as follows:
In the present embodiment, modulation ratio m=0.8, current on line side amplitude Im=8A controls cycle Ts=10-4s；
The positive negative capacitance C of DC sideP=CN=4100 μ F, DC bus-bar voltage Udc=300V；Calculate UdzRange be
0.039 < < Udz< 3.Therefore desirable Udz=1V.
S4, in conjunction with exchange side voltage Ugx, positive and negative small vector action time scale factor k is using unified discontinuous modula tion plan
Slightly, it calculates based on the equivalent modulating wave u under double carried-based PWMsmx(x=a, b, c)；
Wherein, in conjunction with such as Fig. 3, the method for the unified equivalent modulating wave of discontinuous modula tion policy calculation is utilized are as follows:
The modulation ratio m=0.8 of S4.1, three-level inverter, three-phase modulations voltage magnitude Um=138.6V, DC bus electricity
Press Udc=300V, then three-phase voltage controls signal ux(x=a, b, c) can be indicated are as follows:
S4.2, signal u is controlled to the three-phase voltage in above formulaxThe third-harmonic component injection of first time is carried out, for the first time
The third-harmonic component of injection are as follows:
uz1=-0.5 × MAX (ua,ub,uc)-0.5×MIN(ua,ub,uc)
Wherein, MAX is maximizing operator, and MIN is operator of minimizing；
According to the u acquired in real timex, maximum value and minimum value are obtained, above formula is substituted into, calculates uz1.So available
Three-phase voltage after primary injection third-harmonic component controls signal uaz、ubzAnd uczIt indicates are as follows:
S4.3, the linearisation that above formula is shown below:
Wherein,For the u after linear transformationxz(x=a, b, c), MOD are complementation operation；
S4.4, linearizing as a result, controlling signal u to the three-phase voltage in above formula in conjunction with step S4.3xIt carries out second
Third-harmonic component injection, the third-harmonic component of second injection are as follows:
S4.5, three-phase voltage is controlled into signal ux, and the third-harmonic component u of injection for the first timez1It is injected with second
Third-harmonic component uz2It is corresponding mutually sum, obtain the equivalent modulating wave u of unified discontinuous modula tion strategyma、umbAnd umc；
S5, in conjunction with equivalent modulating wave umx, the driving signal of IGBT is generated using double triangular carrier comparative approach；In this implementation
In example, four groups of model of IGBT is chosen, then the pwm signal of four road IGBT of the corresponding output of x, type can also be according to practical need
Choose eight groups, 16 groups etc. of IGBT.
S5.1, compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxGreater than positive triangle
When carrier wave, the pwm signal of the corresponding four roads IGBT of x under the state is exported；
S5.2, compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxGreater than positive triangle
When carrier wave is less than negative triangular carrier, the pwm signal of the corresponding four roads IGBT of x under the state is exported；
S5.3, compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxLess than negative triangle
When carrier wave, the pwm signal of the corresponding four roads IGBT of x under the state is exported.
Generation by controlling pwm signal controls three level mid-point voltages.
Experiment simulation
Fig. 4 is the simulation result diagram in modulation ratio 0.8,0 ° of power-factor angle, emulation the 0.1s moment by modulation algorithm
The modulation algorithm of this patent is switched to by space vector PWM modulation.It can be seen that switching midpoint potential later from the 5th width subgraph
Offset returns near 0, this illustrates that the modulation algorithm of this patent has good neutral point voltage control ability.Wherein the first width
Figure is the unified equivalent modulating wave u of discontinuous modula tion strategyma, the second width subgraph is positive and negative small vector action time scale factor k, the
Three width subgraphs are A phase IGBT output voltage Uao, the 4th width subgraph is that inverter A phase exports electric current ia。
Fig. 5 is the simulation result diagram in modulation ratio 0.4,30 ° of power-factor angle, emulation the 0.1s moment by modulation algorithm
The modulation algorithm of this patent is switched to by space vector PWM modulation.It can be seen that switching midpoint potential later from the 5th width subgraph
Offset returns near 0, this illustrates that the modulation algorithm of this patent has good neutral point voltage control ability.Wherein the first width
Figure is the unified equivalent modulating wave u of discontinuous modula tion strategyma, the second width subgraph is positive and negative small vector action time scale factor k, the
Three width subgraphs are A phase IGBT output voltage Uao, the 4th width subgraph is that inverter A phase exports electric current ia。
Fig. 6 is the experimental result picture in modulation ratio 0.8,0 ° of power-factor angle；In figure the dotted line moment by modulation algorithm by
Space vector PWM modulation is switched to the modulation algorithm of this patent.Channel oscilloscope 2 is positive capacitance voltage value UP, channel oscilloscope 3
The capacitance voltage value that is negative UN, it can be seen that after the modulation algorithm of this patent, positive and negative capacitance voltage be worth difference reduce, i.e., in
Point potential shift amount returns near 0, this illustrates that the modulation algorithm of this patent has good neutral point voltage control ability.Oscillograph
Channel 1 is A phase IGBT output voltage Uao, channel oscilloscope 4 is that inverter A phase exports electric current ia。
Fig. 7 is the experimental result picture in modulation ratio 0.4,30 ° of power-factor angle；In figure the dotted line moment by modulation algorithm by
Space vector PWM modulation is switched to the modulation algorithm of this patent.Channel oscilloscope 2 is positive capacitance voltage value UP, channel oscilloscope 3
The capacitance voltage value that is negative UN, it can be seen that after the modulation algorithm of this patent, positive and negative capacitance voltage be worth difference reduce, i.e., in
Point potential shift amount returns near 0, this illustrates that the modulation algorithm of this patent has good neutral point voltage control ability.Oscillograph
Channel 1 is A phase IGBT output voltage Uao, channel oscilloscope 4 is that inverter A phase exports electric current ia。
Although the illustrative specific embodiment of the present invention is described above, in order to the technology of the art
Personnel understand the present invention, it should be apparent that the present invention is not limited to the range of specific embodiment, to the common skill of the art
For art personnel, if various change the attached claims limit and determine the spirit and scope of the present invention in, these
Variation is it will be apparent that all utilize the innovation and creation of present inventive concept in the column of protection.
Claims (4)
1. a kind of three level mid-point voltage control methods based on unified discontinuous modula tion strategy, which is characterized in that including following
Step:
(1), exchange side voltage U is obtained by voltage-current sensorx, ac-side current ix, DC side total voltage Udc, DC side
Positive pole line voltage UP, DC side negative busbar voltage UN, wherein x=a, b, c；
(2), in conjunction with ac-side current ix, exchange side voltage UxThree-phase voltage, which is obtained, by voltage, current control controls signal ux；
(2.1), to ac-side current ix, exchange side voltage UxIt transforms on two-phase synchronous rotating frame (d, q), formula is such as
Under:
Wherein, θ is the rotation angle of synchronously rotating reference frame q axis；
(2.2), two-phase voltage control signal u is obtained using PI control methodq、ud, governing equation is as follows:
Wherein, KiP、KiLFor proportion adjustment gain and integral adjustment gain,For current instruction value, L is filter inductance
Value；
(2.3), two-phase voltage obtained in step (2.2) is controlled into signal uq、udIt is converted into three-phase voltage control signal ux,
Formula are as follows:
(3), in conjunction with DC side positive pole line voltage UP, negative busbar voltage UN, three-phase voltage control signal uxAnd ac-side current ix,
Positive and negative small vector action time scale factor k is calculated using BANGBANG control method；
(4), signal u is controlled in conjunction with three-phase voltagex, DC side total voltage Udc, positive and negative small vector action time scale factor k use
Unified discontinuous modula tion strategy, calculates based on the equivalent modulating wave u under double carried-based PWMsmx；
(5), in conjunction with equivalent modulating wave umx, the driving signal of IGBT is generated using double triangular carrier comparative approach；
(5.1), compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxGreater than positive triangle carrier wave
When, export the pwm signal of the corresponding IGBT of x under the state；
(5.2), compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxGreater than positive triangle carrier wave
When less than negative triangular carrier, the pwm signal of the corresponding IGBT of x under the state is exported；
(5.3), compare synchronization, equivalent modulating wave umxWith the amplitude size of double triangular carriers, work as umxLess than negative triangular carrier
When, export the pwm signal of the corresponding IGBT of x under the state.
2. the three level mid-point voltage control methods according to claim 1 based on unified discontinuous modula tion strategy, special
Sign is, in the step (3), calculates positive and negative small vector action time scale factor k's using BANGBANG control method
Method are as follows:
(3.1), DC bus unbalance of neutral-point voltage amount Δ U is determinedC:
ΔUC=UN-UP
Wherein, UP、UNRespectively indicate the positive and negative busbar voltage of DC side；
(3.2), by voltage deviation Δ UCWith preset mid-point voltage difference threshold value UdzCompare, if voltage deviation Δ UCIn threshold
Value UdzWithin, then keep k value constant；If voltage deviation Δ UCMore than threshold value UdzWhen, change k value using following methods；
(3.2.1), the value for calculating k', formula are as follows:
K'=sign (Δ UC×ux×ix)
Wherein, function sign (Y) are as follows:
Wherein, the determination method of x are as follows:
Work as ua>0,ub<0,ucWhen < 0, x=a；
Work as ua>0,ub>0,ucWhen < 0, x=c；
Work as ua<0,ub>0,ucWhen < 0, x=b；
Work as ua<0,ub>0,ucWhen > 0, x=a；
Work as ua<0,ub<0,ucWhen > 0, x=c；
Work as ua>0,ub<0,ucWhen > 0, x=b；
(3.2.2), the value for judging k', as k'=0, k is remained unchanged；As k' ≠ 0, k=k'.
3. the three level mid-point voltage control methods according to claim 2 based on unified discontinuous modula tion strategy, special
Sign is, the mid-point voltage difference threshold value UdzValue are as follows:
1) U, is takendzIn DC side total voltage Udc1% within, it may be assumed that Udz1% × U of <dc；
2)、UdzWith midpoint electric current imMaximum value im-maxWith the period of change T of kkMinimum value Tk-minRelationship it is as follows:
Wherein, CP、CNRespectively indicate the size of DC bus capacitor；In order to reduce switching loss, the period of change T of kkSignificantly larger than
The control cycle T of controllers, i.e. Tk> > Ts, then Tk-min> > Ts；im-maxWhen obtaining maximum value, expression formula im-max
=m × Im, wherein m is modulation ratio, ImFor ac-side current ixAmplitude；
3), according to step 1) and 2) obtaining UdzValue range are as follows:
4. the three level mid-point voltage control methods according to claim 1 based on unified discontinuous modula tion strategy, special
Sign is, in the step (4), utilizes the method for the unified equivalent modulating wave of discontinuous modula tion policy calculation are as follows:
(4.1), the modulation ratio that m is three-level inverter is defined, expression formula isUmFor three-phase modulations voltage
Amplitude, then three-phase voltage controls signal uxIt can indicate are as follows:
Wherein, x=a, b, c；
(4.2), signal u is controlled to the three-phase voltage in above formulaxThe third-harmonic component injection for carrying out first time, injects for the first time
Third-harmonic component are as follows:
uz1=-0.5 × MAX (ua,ub,uc)-0.5×MIN(ua,ub,uc)
Wherein, MAX is maximizing operator, and MIN is operator of minimizing；Use uaz、ubzAnd uczIndicate injection uz1Afterwards three
Phase voltage controls signal, expression formula are as follows:
(4.3), the linearisation that above formula is shown below:
Wherein,For the u after linear transformationxz, MOD is complementation operation；
(4.4), signal u is controlled to the three-phase voltage in above formulaxSecondary third-harmonic component injection is carried out, second of injection
Third-harmonic component are as follows:
(4.5), three-phase voltage is controlled into signal ux, and the third-harmonic component u of injection for the first timez1With the three of second of injection
Order harmonic components uz2It is corresponding mutually sum, obtain the equivalent modulating wave u of unified discontinuous modula tion strategyma、umbAnd umc；
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| CN110971135B (en) * | 2018-09-29 | 2021-07-13 | 中车株洲电力机车研究所有限公司 | Three-level full-bridge direct-current converter and control method thereof |
| CN109600065B (en) * | 2018-12-14 | 2020-01-10 | 合肥工业大学 | Discontinuous pulse width modulation method for three-level converter |
| CN111384886B (en) * | 2018-12-29 | 2021-09-17 | 北汽福田汽车股份有限公司 | PWM modulation method and device for motor control |
| CN112152434B (en) * | 2019-06-27 | 2022-06-28 | 北京车和家信息技术有限公司 | Discontinuous pulse width modulation method and device and vehicle |
| CN113098308B (en) * | 2021-03-11 | 2022-07-12 | 中国长江三峡集团有限公司 | Neutral point potential balancing method of three-level converter on direct current side suitable for any bridge arm number |
| CN114448276B (en) * | 2022-04-08 | 2022-06-28 | 茂睿芯（深圳）科技有限公司 | AC-DC conversion circuit and method based on resonant full bridge |
| CN114977870B (en) * | 2022-06-16 | 2022-12-27 | 安徽理工大学 | Unified algorithm for realizing T-type three-level discontinuous modulation carrier |
| CN115037178B (en) * | 2022-08-15 | 2022-11-08 | 深圳市首航新能源股份有限公司 | Method and device for adjusting bus voltage balance capability |
| CN115566918B (en) * | 2022-11-11 | 2023-05-16 | 特变电工西安电气科技有限公司 | Three-level inverter and discontinuous pulse width modulation method and device thereof |
| CN115833637B (en) * | 2023-02-23 | 2023-05-16 | 浙江飞旋科技有限公司 | Neutral point potential control method and device based on three-level DPWM (pulse width modulation) |
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