CN116995944A - Three-level pulse width modulation method and system with positive and negative small vector adjustment factors - Google Patents
Three-level pulse width modulation method and system with positive and negative small vector adjustment factors 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
- H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
- H02M7/53873—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with digital control
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/085—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
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Abstract
The present disclosure provides a three-level pulse width modulation method and system with positive and negative small vector adjustment factors, which relates to the technical field of three-level inverter modulation, and the method comprises the steps of judging a large sector according to the sign of three-phase voltage to obtain a large sector number; correcting the reference voltage space vector according to the large sector number to obtain a corrected space voltage vector; small sector judgment is carried out according to the space voltage vector, a small sector number is obtained, and the space vector acting time is calculated; the pulse width of the three-phase PWM waveform of the positive and negative small vector adjustment factors is calculated and adjusted by the fuzzy logic, the corresponding relation between the PWM waveform and the output of the three-phase inverter is determined, and various corresponding relations under three levels are determined according to the origin of the reference voltage space vector of each large sector, so that the driving signal is distributed to each small sector in each large sector. The method effectively reduces the operation amount, shortens the code length and greatly simplifies the algorithm.
Description
Technical Field
The disclosure relates to the technical field of three-level inverter modulation, in particular to a three-level pulse width modulation method and system with positive and negative small vector adjustment factors.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
With the development of high-voltage high-power electronic devices, PWM (Pulse Width Modulation pulse width modulation) inverters are developed from two-level to three-level and multi-level directions. The diode clamping type three-level converter structure has the advantages that the voltage stress of a switching device is low, the voltage stress of a power tube is half of the voltage of a direct current bus, a multi-layer stepped output voltage can be generated, the waveform is closer to a sine wave, the harmonic content is small, the diode clamping type three-level converter structure is widely applied to medium-high voltage high-power conversion circuits, meanwhile, the problem of unbalanced charge and discharge of a direct current bus capacitor exists in the topological structure, and the neutral-point voltage balance control is needed. In the three-level inverter control strategy, the SVPWM (Space Vector Pulse Width Modulation space vector pulse width modulation) modulation method has high DC bus voltage utilization rate, is easy to realize in a digital mode, is a commonly used three-level pulse width modulation strategy at present, and can play a role in neutral-point potential balance control by adjusting the action time of positive and negative small vectors. The traditional three-level SVPWM algorithm has the problems that the division of large sectors is complex, a large number of data tables are required to be stored in advance and trigonometric function operation is required to be carried out for many times when the action time of a basic voltage vector is calculated, and the driving signal is required to be distributed in each small sector in each large sector too complex.
The large sector judging method in the back-to-back three-level PWM converter vector control system research is researched by the existing method, namely, the positive and negative of a new center vector in an alpha-axis component and a beta-axis component are judged, the magnitude relation of the magnitudes of the new center vector and the new center vector is compared, the sector division is complex, and boundary lines contained in each divided sector are uneven. When the traditional three-level SVPWM algorithm mentioned in the research and simulation of the three-level SVPWM algorithm calculates the action time of the basic space vector, 36 area basic vector action time tables are formulated by subdividing 6 small sectors according to 6 large sectors, and the data tables are huge and easy to make mistakes.
Disclosure of Invention
In order to solve the problems, the three-level pulse width modulation method and system with positive and negative small vector adjustment factors are provided, and the code length is effectively shortened by simplifying a three-level SVPWM algorithm based on reference voltage decomposition, so that the operation efficiency is improved.
According to some embodiments, the present disclosure employs the following technical solutions:
a three-level pulse width modulation method with positive and negative small vector adjustment factors comprises the following steps:
acquiring voltage vectors under a two-phase dq rotating coordinate system and carrying out per unit treatment;
performing anti-PARK transformation and anti-CLARK transformation on the voltage vector to obtain three-phase voltages under a three-phase coordinate system; judging a large sector according to the signs of the three-phase voltages to obtain a large sector number;
correcting the reference voltage space vector according to the large sector number to obtain a corrected space voltage vector; small sector judgment is carried out according to the space voltage vector, a small sector number is obtained, and the space vector acting time is calculated;
the pulse width of the three-phase PWM waveform of the positive and negative small vector adjustment factors is calculated and adjusted by the fuzzy logic, the corresponding relation between the PWM waveform and the output of the three-phase inverter is determined, and various corresponding relations under three levels are determined according to the origin of the reference voltage space vector of each large sector, so that the driving signal is distributed to each small sector in each large sector.
According to some embodiments, the present disclosure employs the following technical solutions:
a three-level pulse width modulation system with positive and negative small vector adjustment factors, comprising:
the data acquisition module is used for acquiring voltage vectors under a two-phase dq rotating coordinate system and carrying out per unit processing;
the voltage conversion module is used for performing anti-PARK conversion and anti-CLARK conversion on the voltage vector to obtain three-phase voltages under a three-phase coordinate system; judging a large sector according to the signs of the three-phase voltages to obtain a large sector number;
the correction module is used for carrying out reference voltage space vector correction according to the large sector number to obtain a corrected space voltage vector; small sector judgment is carried out according to the space voltage vector, a small sector number is obtained, and the space vector acting time is calculated;
the output module is used for calculating the pulse width of the three-phase PWM waveform of which the positive and negative small vector adjustment factors are adjusted by the fuzzy logic, determining the corresponding relation between the PWM waveform and the output of the three-phase inverter, and determining various corresponding relations under three levels according to the origin of the reference voltage space vector of each large sector so that the driving signal is distributed to each small sector in each large sector.
According to some embodiments, the present disclosure employs the following technical solutions:
a medium having stored thereon a program which when executed by a processor performs the steps of the three-level pulse width modulation method with positive and negative small vector adjustment factors.
According to some embodiments, the present disclosure employs the following technical solutions:
an electronic device comprising a memory, a processor and a program stored on the memory and executable on the processor, said processor implementing steps in said three-level pulse width modulation method with positive and negative small vector adjustment factors when said program is executed.
Compared with the prior art, the beneficial effects of the present disclosure are:
the present disclosure only needs to determine the three-phase voltage u a 、u b 、u c The judgment of the large sector can be completed by positive and negative voltages, angle calculation or complex judgment is not needed, and the algorithm is simple;
the present disclosure simplifies the pulse width t of a three-phase PWM waveform with positive and negative small vector adjustment factors by utilizing the rule of hiding in the action time 1on 、t 2on And t 3on The calculation method of the system reduces the calculation amount and saves the calculation time;
according to the method and the device, the driving signal acting time is assigned under 36 conditions without dividing the driving signal into 6 small sectors under 6 large sectors, so that the driving signal acting time assignment is simplified to be only assigned according to 6 conditions of the large sectors, and the code length can be effectively shortened.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate and explain the exemplary embodiments of the disclosure and together with the description serve to explain the disclosure, and do not constitute an undue limitation on the disclosure.
FIG. 1 is a diode clamped three level inverter topology in an embodiment of the present disclosure;
FIG. 2 is a large sector partitioning flow in an embodiment of the present disclosure;
FIG. 3 is a large sector division result in an embodiment of the present disclosure;
FIG. 4 is a three-level inverter voltage space vector diagram in an embodiment of the present disclosure;
FIG. 5 is a division of small sectors under the 1 st large sector in an embodiment of the present disclosure;
FIG. 6 is a graph of membership functions for input and output in an embodiment of the present disclosure;
FIG. 7 is a graph showing the time of action of each vector of the 1 st large sector and the 1 st small sector in an embodiment of the present disclosure;
fig. 8 is a flowchart of a modulation method in an embodiment of the present disclosure.
The specific embodiment is as follows:
the disclosure is further described below with reference to the drawings and examples.
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments in accordance with the present disclosure. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
Example 1
In one embodiment of the present disclosure, a three-level pulse width modulation method with positive and negative small vector adjustment factors is provided, including the steps of:
step one: according to the voltage vector under the two-phase dq rotating coordinate system obtained in the control system, carrying out per unit processing to obtain a direct-axis voltage component u d Quadrature axis voltage component u q 。
Step two: will u d 、u q Performing anti-PARK transformation to obtain two voltage components u under two-phase stationary coordinate system α 、u β Then u is set up α 、u β The three-phase voltage u is obtained through the inverse CLARK conversion a 、u b 、u c The method comprises the steps of carrying out a first treatment on the surface of the Three-level space vector is regarded as being formed by overlapping 6 two-level space vectors based on three-level SVPWM theory of reference voltage decomposition, and according to u a 、u b 、u c Large sector judgment is carried out on the symbols of the number (S) of the large sector, so that a large sector number (S) is obtained;
step three: combining the large sector number and the origins of 6 two-level space vectors, and carrying out reference voltage space vector correction to obtain u α ′、u β ′；
Step four: reference to two-level voltage space vector sector judgment method according to u α ′、u β ' carrying out small sector judgment to obtain a small sector number N; according to NTV (NearestTriangle Vectors) rule and volt-second balance principle, calculating space vector action time and making per unit treatment so as to obtain the action time t of firstly-acted vector and then-acted vector (main and auxiliary vectors) c 、t z Selecting a time reference as T when carrying out per unit processing, and corresponding to a PWM half period;
step five: determining the voltage space vector action sequence and calculating the fuzzy logic to adjust the positive and negative small vector adjustment factors according to the principle of minimum switching times of the power tube switchThe pulse width time of the three-phase PWM waveform is recorded as t from wide to narrow 1on 、t 2on And t 3on The method comprises the steps of carrying out a first treatment on the surface of the Determining the corresponding relation between the PWM waveform and the output of the three-phase inverter to finally obtain the three-phase PWM pulse width time t A 、t B And t C Is a value of (2);
step six: in 6 large sectors, determining positive pulse width time t of three-phase 12 power tubes under three levels according to the origin of reference voltage space vector in each sector a1-4 ，t b1-4 ，t c1-4 And t A 、t B And t C The relationship between them is also t A 、t B And t C The assignment change occurs according to the values of the 6 small sectors, thereby achieving the allocation of the drive signal to each small sector in each large sector.
As an embodiment, the present disclosure proposes a three-level pulse width modulation method with positive and negative small vector factors, simplifying the division of large sectors based on a three-level SVPWM algorithm based on reference voltage decomposition, and in addition, simplifying the allocation method of each small sector driving signal in each large sector by using a rule hidden in the acting time, effectively shortening the code length, and improving the operation efficiency. The specific implementation steps are as follows:
step 1: performing per unit processing according to the voltage vector under the two-phase dq rotating coordinate system obtained in the control system to obtain u d 、u q ；
Wherein, per unit treatment process is:
selecting a voltage reference asU dc Is the dc bus voltage of the inverter.
Step 2: will u d 、u q Performing anti-PARK transformation to obtain u α 、u β Then u is set up α 、u β Obtaining u through inverse CLARK transformation a 、u b 、u c The method comprises the steps of carrying out a first treatment on the surface of the Three-level space vector is regarded as formed by overlapping 6 two-level space vectors based on three-level SVPWM theory of reference voltage decomposition, and rootAccording to u a 、u b 、u c Large sector judgment is carried out on the symbols of the number (S) of the large sector, so that a large sector number (S) is obtained;
the dividing steps of the large sector are as follows:
step 2.1: transforming the reference voltage from an alpha beta coordinate system to an abc three-phase coordinate system;
step 2.2: according to u a 、u b 、u c Sector division is performed by the symbols of (a), and the flow chart is shown in fig. 2:
step 2.2.1: if u is a >0, then a=1; if u is a < 0, then a=0; if u is a =0, then further determination of u is required b If u is the sign of b >0, then a=1, otherwise a=0.
Step 2.2.2: if u is b >0, then b=1; if u is b < 0, then b=0; if u is b =0, then further determination of u is required c If u is the sign of c B=1 if >0, otherwise b=0.
Step 2.2.3: if u is c >0, then c=1; if u is c < 0, then c=0; if u is c =0, then further determination of u is required a If u is the sign of a C=1 if >0, otherwise c=0.
Step 2.2.4: the large sector number is calculated from the value of A, B, C described above.
S tmp ＝4C+2B+A
Wherein A, B, C is 0 or 1, S respectively tmp An intermediate variable that divides large sectors.
The large sector division results are shown in fig. 3, each large sector including a bar boundary.
S tmp The correspondence with the large sector S is shown in table 1 below:
TABLE 1 Large sector correspondence
| S tmp | 1 | 3 | 2 | 6 | 4 | 5 |
| S | 1 | 2 | 3 | 4 | 5 | 6 |
Step 3: combining the large sector number and the origins of 6 two-level space vectors, and carrying out reference voltage space vector correction to obtain u α ′、u β ′；
Three-level space voltage vector with V 0 Is the origin of coordinates (V) 0 Zero vectors, i.e., (000, -1-1-1, 111 vectors) in FIG. 4, are converted to two-level space voltage vectors of 6 large sectors, respectively at V 1 、V 2 、V 3 、V 4 、V 5 、V 6 As shown in fig. 4, in order to properly convert the three-level space voltage vector into the two-level space voltage vector, the origin of the reference space voltage vector must be shifted to the origin of 6 large sectors, so that the reference space voltage vector needs to be corrected. The reference voltage space vector correction formula for each large sector is shown in table 2 below:
TABLE 2 correction values of reference voltage space vector in large sectors
Step 4: reference to two-level voltage space vector sector judgment method according to u α ′、u β ' carrying out small sector judgment to obtain a small sector number N; according to NTV (Nearest Triangle Vectors) rule and volt-second balance principle, calculating space vector acting time and performing per unit treatment to obtain t c 、t z Selecting a time reference as T when carrying out per unit processing, and corresponding to a PWM half period;
step 4.1: with reference to the two-level voltage space vector sector judging method and the large sector dividing flow, three symbol functions are defined to judge the small sector:
wherein v is a 、v b 、v c Representing three auxiliary variables.
Step 4.1.1: if v a >0, then a=1; if v a <0, then a=0; if v a =0, then further determination of v is required b If v is b >0, then a=1, otherwise a=0.
Step 4.1.2: if v b >0, then b=1; if v b <0, then b=0; if v b =0, then further determination of v is required c If v is c B=1, otherwise b=0.
Step 4.1.3: if v c >0, then c=1; if v c <0, then c=0; if v c =0, then further determination of v is required a If v is a C=1 if >0, otherwise c=0.
Where a, b, c represent auxiliary variables defined in small sector division, and the value obtained by the above calculation is 0 or 1, which acts as A, B, C defined in large sector division.
Step 4.1.4: and calculating to obtain the small sector number according to the values of a, b and c.
N tmp ＝4c+2b+a
N tmp The correspondence with small sector N is shown in table 3 below:
TABLE 3 correspondence of small sectors
| N tmp | 3 | 1 | 5 | 4 | 6 | 2 |
| N | 1 | 2 | 3 | 4 | 5 | 6 |
Taking the first large sector as an example, the small sectors are divided as shown in fig. 5, each small sector contains a boundary, and the division of the small sectors in other large sectors is the same.
Step 4.2: calculation ofVector time of action t c And t z In three levels, t c Corresponding to the first-applied vector, called the principal vector, t z The vector corresponding to the latter action is called the secondary vector.
Step 4.2.1: 3 intermediate variables X, Y and Z are introduced to calculate time t c And t z The expression is as follows:
step 4.2.2: obtaining corresponding t under different small sector numbers N c 、t z As shown in table 4 below;
TABLE 4 basic space vector on time in each small sector
| Small sector number N | 1 | 2 | 3 | 4 | 5 | 6 |
| t c | -Z | Z | X | -X | -Y | Y |
| t z | X | Y | -Y | Z | -Z | -X |
Step 4.2.3: also, because X-Y-z=0, t in each small sector c +t z The values of (2) are shown in table 5 below:
TABLE 5 t within each small sector c +t z Values of (2)
| Small sector number N | 1 | 2 | 3 | 4 | 5 | 6 |
| t c +t z | Y | X | Z | -Y | -X | -Z |
Step 5: determining the voltage space vector action sequence and calculating the pulse width t of the three-phase PWM waveform of which the fuzzy logic adjusts the positive and negative small vector adjustment factors according to the principle that the switching times of the power tube switch are minimum 1on 、t 2on And t 3on The method comprises the steps of carrying out a first treatment on the surface of the Determining the corresponding relation between the PWM waveform and the output of the three-phase inverter to finally obtain the three-phase PWM positive pulse width t A 、t B And t C Is a value of (2);
step 5.1: in three-level vector space distribution, small vector V 1 、V 2 、V 3 、V 4 、V 5 、V 6 The space vectors at two levels are synthesized as zero vectors in the two-level vector synthesis, respectively. According to the volt-second balance principle, the action time of the obtained small vector is as follows:
t x ＝1-t c -t z ＝1-(t c +t z )，(x＝1,2,...6)
the small vectors in the three levels are a pair of redundant vectors, and are classified into a positive small vector (midpoint potential increase) and a negative small vector (midpoint potential decrease) according to the influence on the neutral point potential, such as small vector V 1 The positive small vector of (2) is 100 and the negative small vector is 0-1-1.
The neutral point potential balance control can be realized by adjusting the time of the positive and negative small vectors, and the action time t of the small vectors x Divided into t xP (positive small vector action time) and t xN (negative small vector on time). The action time of the positive and negative small vectors is respectively set asWherein f is an adjusting factor, and the value range is [ -1,1]。
Combining the difference between the two voltage dividing capacitor voltages in fig. 1, Δv=v C1 -V C2 And midpoint current i o According to the formulated fuzzy logic controller, a two-input single-output fuzzy logic controller is utilizedThe rule is edited and the value of the adjustment factor f is output. When f=1, the small vectors are all positive small vectors, when f= -1, the small vectors are all negative small vectors, and when f=0, the positive and negative small vectors act for equal time.
Step 5.1.1: one input of the two-input single-output fuzzy logic controller is the difference DeltaV=V between two capacitor voltages C1 -V C2 Another input is the midpoint current i o (taking the inflow inverter positive) and outputting as the adjustment factor f. The fuzzy sets of the three are defined as follows: NB, NM, NS, ZO, PS, PM and PB, and domains are: [ -1,1]. The membership function distribution diagram is shown in fig. 6.
TABLE 6 fuzzy variable adjustment factor control rules table
Step 5.2: similar to the two-level SVPWM switch combination, the switching state of each phase switching tube needs to go through 0 state from 1 to-1 or-1 to 1 in order to reduce switching loss and inverter voltage harmonics, 1 and-1 are not allowed to directly transform, and only one phase switch is allowed to change at a time.
Step 5.2.1: taking the 1 st large sector and the 1 st small sector (S=1, N=1) as examples, the voltage space vector acts in the order of V 1N ->V 7 ->V 8 ->V 1P ->V 8 ->V 7 ->V 1N . The time of action of each vector is shown in FIG. 7, where T x ＝t x ×T。
Step 5.2.2: substituting for step 4.2.2 and4.2.3 t of different small sectors obtained c ，t z And t c +t z Obtaining the pulse width t of the three-phase PWM waveform with the positive and negative small vector adjustment factors 1on 、t 2on And t 3on As shown in table 7.
TABLE 7 t for each small sector 1on 、t 2on And t 3on Values of (2)
Thereby obtaining the pulse width t of the three-phase PWM half period under different small sectors A 、t B And t C And t 1on 、t 2on And t 3on The correspondence of (2) is shown in table 8, and specific values are substituted to obtain table 9.
TABLE 8 t for each small sector A 、t B And t C Values of (2)
| Small sector number N | 1 | 2 | 3 | 4 | 5 | 6 |
| t A | t 1on | t 2on | t 3on | t 3on | t 2on | t 1on |
| t B | t 2on | t 1on | t 1on | t 2on | t 3on | t 3on |
| t C | t 3on | t 3on | t 2on | t 1on | t 1on | t 2on |
TABLE 9 t for each small sector A 、t B And t C Values of (2)
In particular, when f=0, i.e. when the positive and negative small vectors are active for equal time, the small sectors n=1 and n=4, t A 、t B And t C The calculation formulas of (2) are consistent; when the small sectors n=2 and n=5, t A 、t B And t C The calculation formulas of (2) are consistent; when the small sectors n=3 and n=6, t A 、t B And t C Is consistent with the calculation formula of (2).
Step 6: in 6 large sectors, t is determined at three levels according to the origin of the reference voltage space vector in each sector a1-4 ，t b1-4 ，t c1-4 And t A 、t B And t C The relationship between them is also t A 、t B And t C The assignment change is carried out according to the values of the 6 small sectors, so that the purpose that the driving signals distribute each small sector (36 kinds in total) in each large sector is achieved, but the assignment of the 6 large sectors is completed, and the algorithm is greatly simplified.
Step 6.1: the 6 large sectors are respectively in V 1 、V 2 、V 3 、V 4 、V 5 、V 6 The small vectors are the origin of coordinates, each small vector being a pair of redundant positive and negative small vectors, as shown in Table 10 below:
positive and negative small vectors corresponding to each small vector in Table 10
| Small vectors | V 1 | V 2 | V 3 | V 4 | V 5 | V 6 |
| Positive small vector | 100 | 110 | 010 | 011 | 001 | 101 |
| Negative small vector | 0-1-1 | 00-1 | -10-1 | -100 | -1-10 | 0-10 |
Step 6.2: according to the principle that the switching times of the power tube switch are minimum, the voltage space vector action sequence starts from a negative small vector, passes through a main vector and an auxiliary vector to a positive small vector, passes through the auxiliary vector and the main vector, and ends to the negative small vector.
Step 6.2.1: in the 1 st large sector, the small vector change order is: 0-1-1- >100- >0-1-1.
Step 6.2.2: for phase a, the level state change is: 0->1->0，s a1-4 The change of the switching tube is as follows:
table 11 s a1-4 Switching tube variation
| s a1 | 0 | 1 | 0 |
| s a2 | 1 | 1 | 1 |
| s a3 | 1 | 0 | 1 |
| s a4 | 0 | 0 | 0 |
Cause s a1 And s a3 The high and low level states are opposite, s a2 And s a4 The high and low level states are opposite, so only s is calculated a1 Sum s a2 Pulse width time t of (2) a1 ，t a2 Obtaining t a1 ＝t A ，t a2 ＝1。
Step 6.2.3: for phase b, the level state change is: -1->0->-1，s b1-4 The change of the switching tube is as follows:
table 12 s b1-4 Switching tube variation
| s b1 | 0 | 0 | 0 |
| s b2 | 0 | 1 | 0 |
| s b3 | 1 | 1 | 1 |
| s b4 | 1 | 0 | 1 |
Cause s b1 And s b3 The high and low level states are opposite, s b2 And s b4 The high and low level states are opposite, so only s is calculated b1 Sum s b2 Pulse width time t of (2) b1 ，t b2 Obtaining t b1 ＝0，t a2 ＝t B 。
Step 6.2.4: for phase c, the level state change is: -1->0->-1，s c1-4 The change of the switching tube is as follows:
table 13 s b1-4 Switching tube variation
| s c1 | 0 | 0 | 0 |
| s c2 | 0 | 1 | 0 |
| s c3 | 1 | 1 | 1 |
| s c4 | 1 | 0 | 1 |
Cause s c1 And s c3 The high and low level states are opposite, s c2 And s c4 The high and low level states are opposite, so only s is calculated c1 Sum s c2 Pulse width time t of (2) c1 ，t c2 Obtaining t c1 ＝0，t c2 ＝t C 。
Step 6.2.5: according to the method, the pulse width time of each switching tube under 6 large sectors is obtained as follows:
TABLE 14 pulse width time for each switching tube for 6 large sectors
Due to t A 、t B And t C The assignment changes according to the values of the 6 small sectors, thereby achieving the purpose of distributing the driving signals to each small sector in each large sector.
Example 2
In one embodiment of the present disclosure, a three-level pulse width modulation system with positive and negative small vector adjustment factors is provided, comprising:
the data acquisition module is used for acquiring voltage vectors under a two-phase dq rotating coordinate system and carrying out per unit processing;
the voltage conversion module is used for performing anti-PARK conversion and anti-CLARK conversion on the voltage vector to obtain three-phase voltages under a three-phase coordinate system; judging a large sector according to the signs of the three-phase voltages to obtain a large sector number;
the correction module is used for carrying out reference voltage space vector correction according to the large sector number to obtain a corrected space voltage vector; small sector judgment is carried out according to the space voltage vector, a small sector number is obtained, and the space vector acting time is calculated;
the output module is used for calculating the pulse width of the three-phase PWM waveform of which the positive and negative small vector adjustment factors are adjusted by the fuzzy logic, determining the corresponding relation between the PWM waveform and the output of the three-phase inverter, and determining various corresponding relations under three levels according to the origin of the reference voltage space vector of each large sector so that the driving signal is distributed to each small sector in each large sector.
Example 3
In one embodiment of the present disclosure, a medium is provided having a program stored thereon, which when executed by a processor, implements the steps of the three-level pulse width modulation method with positive and negative small vector adjustment factors.
Example 4
An embodiment of the present disclosure provides an electronic device, including a memory, a processor, and a program stored on the memory and executable on the processor, where the processor implements steps in the three-level pulse width modulation method with positive and negative small vector adjustment factors when the program is executed.
The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While the specific embodiments of the present disclosure have been described above with reference to the drawings, it should be understood that the present disclosure is not limited to the embodiments, and that various modifications and changes can be made by one skilled in the art without inventive effort on the basis of the technical solutions of the present disclosure while remaining within the scope of the present disclosure.
Claims (10)
1. The three-level pulse width modulation method with the positive and negative small vector adjustment factors is characterized by comprising the following steps of:
acquiring voltage vectors under a two-phase dq rotating coordinate system and carrying out per unit treatment;
performing anti-PARK transformation and anti-CLARK transformation on the voltage vector to obtain three-phase voltages under a three-phase coordinate system; judging a large sector according to the signs of the three-phase voltages to obtain a large sector number;
correcting the reference voltage space vector according to the large sector number to obtain a corrected space voltage vector; small sector judgment is carried out according to the space voltage vector, a small sector number is obtained, and the space vector acting time is calculated;
the pulse width of the three-phase PWM waveform of the positive and negative small vector adjustment factors is calculated and adjusted by the fuzzy logic, the corresponding relation between the PWM waveform and the output of the three-phase inverter is determined, and various corresponding relations under three levels are determined according to the origin of the reference voltage space vector of each large sector, so that the driving signal is distributed to each small sector in each large sector.
2. The three-level pulse width modulation method with positive and negative small vector adjustment factors according to claim 1, wherein the step of performing large sector judgment according to the sign of the three-phase voltage to obtain a large sector number is:
s1, performing anti-PARK conversion on a voltage vector to obtain reference voltage under an alpha beta coordinate system, and then performing anti-CLARK conversion on the reference voltage from the alpha beta coordinate system to an abc three-phase coordinate system;
s2, according to the three-phase voltage u under the three-phase coordinate system a 、u b 、u c Large sector judgment and division are carried out on the symbols of the number (2); if u is a >0, then a=1; if u is a < 0, then a=0; if u is a =0, then further judge u b If u is the sign of b >0, then a=1, otherwise a=0;
if u is b >0, then b=1; if u is b < 0, then b=0; if u is b =0, then further judge u c If u is the sign of c B=1 if >0, otherwise b=0;
if u is c >0, then c=1; if u is c < 0, then c=0; if u is c =0, then further judge u a If u is the sign of a C=1 if >0, otherwise c=0;
and S3, calculating according to the A, B, C value to obtain a large sector number.
3. The three-level pulse width modulation method with positive and negative small vector adjustment factors according to claim 1, wherein the reference voltage space vector is corrected according to the large sector number, and the corrected space voltage vector is obtained by combining the large sector number and the origins of 6 two-level space vectors, and the reference voltage space vector is corrected.
4. The three-level pulse width modulation method with positive and negative small vector adjustment factors according to claim 1, wherein the method for carrying out small sector judgment division according to the space voltage vector and obtaining the small sector number is as follows: with reference to the two-level voltage space vector sector judging method and the large sector dividing flow, three symbol functions are defined to judge the small sector and obtain the small sector number.
5. The three-level pulse width modulation method with positive and negative small vector adjustment factors according to claim 1, wherein the vector on time t is calculated c And t z In three levels, t c Corresponding to the vector acting first, the main vector, t z The vector corresponding to the post-action is a secondary vector; three intermediate variables X, Y and Z are introduced to calculate time t c And t z The method comprises the steps of carrying out a first treatment on the surface of the Obtaining corresponding t under different small sector numbers N c 、t z 。
6. The three-level pulse width modulation method with positive and negative small vector adjustment factors according to claim 1, wherein the method for calculating the pulse width of the three-phase PWM waveform of which the fuzzy logic adjusts the positive and negative small vector adjustment factors and determining the correspondence between the PWM waveform and the output of the three-phase inverter comprises: determining the voltage space vector action sequence and calculating the pulse width t of the three-phase PWM waveform of which the fuzzy logic adjusts the positive and negative small vector adjustment factors according to the principle that the switching times of the power tube switch are minimum 1on 、t 2on And t 3on The method comprises the steps of carrying out a first treatment on the surface of the Determining the corresponding relation between the PWM waveform and the output of the three-phase inverter to obtain t A 、t B And t C Is a value of (2).
7. The three-level pulse width modulation method with positive and negative small vector adjustment factors according to claim 6, wherein t is determined at three levels from the origin of the reference voltage space vector in each sector among 6 large sectors a1-4 t b1-4 t c1-4 And t A 、t B And t C The relationship between them is also t A 、t B And t C According to 6The values of the small sectors are assigned to change so that the drive signal is assigned to each small sector in each large sector.
8. A three-level pulse width modulation system with positive and negative small vector adjustment factors, comprising:
the data acquisition module is used for acquiring voltage vectors under a two-phase dq rotating coordinate system and carrying out per unit processing;
the voltage conversion module is used for performing anti-PARK conversion and anti-CLARK conversion on the voltage vector to obtain three-phase voltages under a three-phase coordinate system; judging a large sector according to the signs of the three-phase voltages to obtain a large sector number;
the correction module is used for carrying out reference voltage space vector correction according to the large sector number to obtain a corrected space voltage vector; small sector judgment is carried out according to the space voltage vector, a small sector number is obtained, and the space vector acting time is calculated;
the output module is used for calculating the pulse width of the three-phase PWM waveform of which the positive and negative small vector adjustment factors are adjusted by the fuzzy logic, determining the corresponding relation between the PWM waveform and the output of the three-phase inverter, and determining various corresponding relations under three levels according to the origin of the reference voltage space vector of each large sector so that the driving signal is distributed to each small sector in each large sector.
9. A medium having stored thereon a program which when executed by a processor performs the steps of the three-level pulse width modulation method with positive and negative small vector adjustment factors according to any one of claims 1-7.
10. An electronic device comprising a memory, a processor and a program stored on the memory and executable on the processor, wherein the processor performs the steps in the three-level pulse width modulation method with positive and negative small vector adjustment factors of any one of claims 1-7 when the program is executed.
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