阅读说明：本技术 一种多源变换器的空间矢量调制方法 (Space vector modulation method of multi-source converter ) 是由 郭希铮 邹方朔 罗章 游小杰 王琛琛 王剑 周明磊 郝瑞祥 于 2019-10-08 设计创作，主要内容包括：本发明提供多源变换器的空间矢量调制方法,属于多源变换器的脉冲宽度调制技术领域。包括结合标幺化直角坐标系,构建中性点电位不平衡空间矢量模型；将小矢量划分为矢量组一和矢量组二,确定矢量组一和矢量组二中的小矢量组成的小扇区的边界方程；根据小扇区的边界方程,确定参考电压矢量；计算所在小扇区的基本矢量的作用时间比例；根据作用时间比例对矢量组一和所述矢量组二进行混合调制,实现直流侧功率分配,获取多种能量流通模式。本发明采用基于坐标运算的方法来解决中点电压不平衡带来的问题,并减少运算量；采用矢量组一和矢量组二混合调制,通过控制矢量组一和矢量组二的作用时间权重,实现了直流侧的功率分配,得到更多的能量流通模式。(The invention provides a space vector modulation method of a multi-source converter, belonging to the technical field of pulse width modulation of multi-source converters. The method comprises the steps of constructing a neutral point potential unbalance space vector model by combining a per-unit rectangular coordinate system; dividing the small vectors into a vector group I and a vector group II, and determining a boundary equation of a small sector formed by the small vectors in the vector group I and the vector group II; determining a reference voltage vector according to a boundary equation of the small sector; calculating the action time proportion of the basic vector of the small sector; and performing mixed modulation on the vector group I and the vector group II according to the action time proportion, realizing power distribution at the direct current side and acquiring various energy circulation modes. The invention adopts a method based on coordinate operation to solve the problem caused by the unbalanced midpoint voltage and reduce the operation amount; and the vector group I and the vector group II are mixed and modulated, and the action time weight of the vector group I and the vector group II is controlled, so that the power distribution of the direct current side is realized, and more energy circulation modes are obtained.)

1. A space vector modulation method of a multi-source converter comprises a first direct-current energy source, a second direct-current energy source and a converter, wherein the first direct-current energy source and the second direct-current energy source are connected with the direct-current side of the converter, and the alternating-current side of the converter is connected with a three-phase alternating-current motor; the converter comprises an upper bridge arm switch, a middle bridge arm switch and a lower bridge arm switch; one end of the upper bridge arm switch is connected to the positive end of the first direct current energy source, one end of the lower bridge arm switch is connected to the negative end of the first direct current energy source and the negative end of the second direct current energy source, and one end of the middle bridge arm switch is connected to the positive end of the second direct current energy source; the other end of the upper bridge arm switch, the other end of the lower bridge arm switch and the other end of the middle bridge arm switch are connected with the three-phase alternating current motor; the method is characterized in that:

step S110: constructing a neutral point potential unbalance space vector model by combining a per-unit rectangular coordinate system;

step S120: in a neutral point potential unbalance space vector model, dividing small vectors into a vector group I and a vector group II, and determining a boundary equation of a small sector formed by the small vectors in the vector group I and the vector group II;

step S130: determining a reference voltage vector according to a boundary equation of the small sector;

step S140: calculating the action time proportion of the basic vector of the small sector according to the reference voltage vector;

step S150: and performing mixed modulation on the vector group I and the vector group II according to the action time proportion, realizing power distribution at the direct current side and obtaining multiple energy circulation modes.

2. The method according to claim 1, wherein step S110 specifically includes:

the first direct current energy source and the second direct current energy source are respectively V₁、V₂The upper bridge arm switch is turned on, the lower bridge arm switch and the middle bridge arm switch are turned off, and the output phase voltage is V₁-V₂(ii) a The middle bridge arm switch is switched on, the upper bridge arm switch and the lower bridge arm switch are switched off, and the output phase voltage is 0; the lower bridge arm switch is turned on, the upper bridge arm switch and the middle bridge arm switch are turned off, and the output phase voltage is-V₂；

When V is₁≠2V₂The large vector forms a large sector one, a large sector two, a large sector three, a large sector four, a large sector five and a large sector six.

3. The method according to claim 2, wherein step S120 specifically includes:

the vector group one comprises a small vector 100, a small vector 110, a small vector 010, a small vector 011, a small vector 001 and a small vector 101, and the vector group two comprises a small vector 211, a small vector 221, a small vector 121, a small vector 122, a small vector 112 and a small vector 212;

the number of small sectors which are divided into large voltage space vector sectors by small vectors in the vector group I and the vector group II is 4, because V₁≠2V₂The four small sectors are not all regular triangles, namely small sector ①, small sector ②, small sector ③ and small sector ④;

with the magnitude of the large vector being 2V₁And/3 is a reference value, and the per-unit length is defined as:

y＝V₂/V₁，x＝(V₁-V₂)/V₁；

and obtaining the per-unit coordinates of all the voltage space vectors and obtaining the boundary equation of each small sector.

4. The method according to claim 3, wherein the step S130 specifically comprises:

V₁<2V₂in the first large sector, the changed per-unit coordinates of the small vector 100, the small vector 110, the small vector 211, the small vector 221, and the small vector 210 are respectively:

(y,0)、(x,0)、

the coordinates of the large vector 200, the large vector 220 and the zero vector are:

(1,0)、

obtaining a boundary equation of the small sector divided by the vector group I and the vector group II according to the per-unit coordinates, and setting the per-unit coordinates of the reference voltage vector as (x)₀,y₀) The small sector is judged as follows:

for a small sector divided by a vector group, when

for vector group binary divided small sector, the method is as followsWhen the reference voltage vector is in small sector ④, when

5. The method according to claim 4, wherein the step S140 specifically comprises:

calculating the action time of the small vector through per unit coordinates according to a volt-second balance basic principle;

let reference voltage vector U_refWhich is composed of three basic small vectors u of the small sector₁、u₂、u₃Linear combination equivalent, the synthetic relationship is as follows:

in the formula, T_SFor a switching period, T₁、T₂、T₃Are respectively basic small vectors u₁、u₂、u₃The action time of (c);

elementary small vector u₁、u₂、u₃Ratio of action time

d_k＝T_k/T_S(0≤d_k1) k is 1,2,3, the formula (1) is changed to

Let the coordinates of three basic small vectors of any small sector be (x)₁,y₁)、(x₂,y₂)、(x₃,y₃) The per unit coordinate of the reference voltage vector is (x)₀,y₀) D can be calculated by using the coordinates₁、d₂、d₃The calculation formula is as follows:

6. the method according to claim 5, wherein the step S150 specifically comprises:

defining vector group action time weights K_d(0≤K_dLess than or equal to 1), adding K_dThe voltage vector allocated to the vector group two and the vector combination is U_ref2Will be (1-K)_d) To vector group one, vector group one resultant voltage vector U_ref1Then the reference voltage vector is represented as

U_ref＝U_ref1+U_ref2(4)

Obtaining a voltage vector expression formed by combining a vector group I and a vector group II from the formula (2)

7. The method of claim 6, wherein the power distribution on the DC side is achieved by considering that the modulation effects of vector group one and vector group two are the same, but the switch states are different, the current effects on the two groups of independent energy sources on the DC side are different, and vector group one only affects V₂Current i of_dc2Vector set two simultaneous effects V₁Current i of_dc1And V₂Current i of_dc2And i is_dc1＝-i_dc2The dc-side current i can then be divided by the allocation of the time-weighted vector contribution in one switching cycle_dc1、i_dc2And controlling to realize power distribution of two groups of independent energy sources at the direct current side.

8. The method of claim 7, wherein said deriving the plurality of energy circulation modes comprises:

the vector group I and the vector group II are mixed and modulated, and the action time proportion distribution of the vector group I and the vector group II is controlled to realize two groups of independent energy sources V on the direct current side₁、V₂Current control of (V)₁、V₂The working mode of the motor is not fixed any more, and more current (energy) circulation modes can be obtained between the motor and the three vehicles, which comprises the following steps:

the first mode is as follows: v₂Auxiliary V₁Simultaneously outputting energy to the three-phase alternating current motor;

and a second mode: v₁Outputting energy to the three-phase alternating current motor independently;

and a third mode: v₂Outputting energy to the three-phase alternating current motor independently;

and a fourth mode: v₁Outputting energy to a three-phase AC motorAt the same time to V₂Outputting energy;

and a fifth mode: v₂Auxiliary V₁Absorbing energy from the three-phase AC motor;

mode six: v₁Absorbing energy from the three-phase alternating current motor alone;

mode seven: v₂Absorbing energy from the three-phase alternating current motor alone;

and a mode eight: v₁Absorbing energy from a three-phase ac motor while simultaneously passing from V₂Energy is absorbed.

Technical Field

The invention relates to the technical field of pulse width modulation of a multi-source converter, in particular to a space vector modulation method of the multi-source converter.

Background

Space Vector Pulse Width Modulation (SVPWM) is a Modulation technology for controlling a converter according to the Vector switching of converter Space voltage (current), and the main idea is that when three-phase symmetrical sine-wave voltage is used for supplying power, an ideal flux linkage circle of a stator of a three-phase symmetrical motor is taken as a reference standard, different switching modes of the converter are adopted for switching Space voltage vectors, the generated actual flux approaches to the flux of a reference circle, and the switching of the converter is determined according to the comparison result of the actual flux and the reference circle to form a PWM waveform. Compared with the direct SPWM technology, the method has the main advantages of higher harmonic optimization degree, improvement of the voltage utilization rate and the dynamic response speed of the motor, suitability for a digital control system and the like.

The modulation method of the current multisource converter is mainly an improved SVPWM algorithm, the algorithm divides two energy sources at the direct current side of the multisource converter into three or four working modes through different switch states to carry out corresponding modulation, the two energy sources at the direct current side are combined according to the corresponding working modes, different direct current side voltage driving motors can be realized, the alternating current side outputs two-level phase voltages, the modulation algorithm is essentially a two-level universal bridge, and a combined trigonometric function calculation method is adopted for calculating the space vector action time.

Three or four working modes fixed by the current SVPWM algorithm limit more energy circulation modes between a direct current side energy source and a motor, the harmonic performance of two-level output phase voltage obtained at an alternating current side is poorer than that of multi-level output phase voltage, a scheme for solving the problem of midpoint potential imbalance is not provided, and the operation amount is increased by adopting the combination of trigonometric function calculation space vector action time. Therefore, it is necessary to provide a modulation method of a multi-source converter to improve the above disadvantages of the current modulation method.

Disclosure of Invention

The present invention is directed to a method for modulating a space vector of a multi-source converter, so as to solve at least one technical problem in the background art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a space vector modulation method of a multi-source converter, wherein the multi-source converter comprises a first direct-current energy source, a second direct-current energy source and a converter, the first direct-current energy source and the second direct-current energy source are both connected with the direct-current side of the converter, and the alternating-current side of the converter is connected with a three-phase alternating-current motor; the converter comprises an upper bridge arm switch, a middle bridge arm switch and a lower bridge arm switch; one end of the upper bridge arm switch is connected to the positive end of the first direct current energy source, one end of the lower bridge arm switch is connected to the negative end of the first direct current energy source and the negative end of the second direct current energy source, and one end of the middle bridge arm switch is connected to the positive end of the second direct current energy source; the other end of the upper bridge arm switch, the other end of the lower bridge arm switch and the other end of the middle bridge arm switch are connected with the three-phase alternating current motor; the method comprises the following steps:

step S110: constructing a neutral point potential unbalance space vector model by combining a per-unit rectangular coordinate system;

step S120: in a neutral point potential unbalance space vector model, dividing small vectors into a vector group I and a vector group II, and determining a boundary equation of a small sector formed by the small vectors in the vector group I and the vector group II;

step S130: determining a reference voltage vector according to a boundary equation of the small sector;

step S140: calculating the action time proportion of the basic vector of the small sector according to the reference voltage vector;

step S150: and performing mixed modulation on the vector group I and the vector group II according to the action time proportion, realizing power distribution at the direct current side and obtaining multiple energy circulation modes.

Preferably, the step S110 specifically includes:

the first direct current energy source and the second direct current energy source are respectively V₁、V₂The upper bridge arm switch is turned on, the lower bridge arm switch and the middle bridge arm switch are turned off, and the output phase voltage is V₁-V₂(ii) a The middle bridge arm switch is switched on, the upper bridge arm switch and the lower bridge arm switch are switched off, and the output phase voltage is 0; the lower bridge arm switch is turned on, the upper bridge arm switch and the middle bridge arm switch are turned off, and the output phase voltage is-V₂；

When V is₁≠2V₂The large vector forms a large sector one, a large sector two, a large sector three, a large sector four, a large sector five and a large sector six.

Preferably, the step S120 specifically includes:

the vector group one comprises a small vector 100, a small vector 110, a small vector 010, a small vector 011, a small vector 001 and a small vector 101, and the vector group two comprises a small vector 211, a small vector 221, a small vector 121, a small vector 122, a small vector 112 and a small vector 212;

the number of small sectors which are divided into large voltage space vector sectors by small vectors in the vector group I and the vector group II is 4, because V₁≠2V₂The four small sectors are not all regular triangles, namely small sector ①, small sector ②, small sector ③ and small sector ④;

with the magnitude of the large vector being 2V₁And/3 is a reference value, and the per-unit length is defined as:

y＝V₂/V₁，x＝(V₁-V₂)/V₁；

and obtaining the per-unit coordinates of all the voltage space vectors and obtaining the boundary equation of each small sector.

Preferably, the step S130 specifically includes:

V₁<2V₂time, large sector one, changeThe per-unit coordinates of the quantized small vector 100, the small vector 110, the small vector 211, the small vector 221, and the small vector 210 are respectively:

the coordinates of the large vector 200, the large vector 220 and the zero vector are:

obtaining a boundary equation of the small sector divided by the vector group I and the vector group II according to the per-unit coordinates, and setting the per-unit coordinates of the reference voltage vector as (x)₀,y₀) The small sector is judged as follows:

for a small sector divided by a vector group, when

When the reference voltage vector is in small sector ①, when

When the reference voltage vector is in small sector ③, when

When the reference voltage vector is in small sector ④, otherwise, the reference voltage vector is in small sector ②;

for vector group binary divided small sector, the method is as follows

When the reference voltage vector is in small sector ④, whenWhen the reference voltage vector is in small sector ①, whenWhen the reference voltage vector is in the small sector ③, otherwise, the reference voltage vector is in the small sector②。

Preferably, the step S140 specifically includes:

calculating the action time of the small vector through per unit coordinates according to a volt-second balance basic principle;

let reference voltage vector U_refWhich is composed of three basic small vectors u of the small sector₁、u₂、u₃Linear combination equivalent, the synthetic relationship is as follows:

in the formula, T_SFor a switching period, T₁、T₂、T₃Are respectively basic small vectors u₁、u₂、u₃The action time of (c);

elementary small vector u₁、u₂、u₃Ratio of action time

d_k＝T_k/T_S(0≤d_k1) k is 1,2,3, the formula (1) is changed to

Let the coordinates of three basic small vectors of any small sector be (x)₁,y₁)、(x₂,y₂)、(x₃,y₃) The per unit coordinate of the reference voltage vector is (x)₀,y₀) D can be calculated by using the coordinates₁、d₂、d₃The calculation formula is as follows:

preferably, the step S150 specifically includes:

defining vector group action time weights K_d(0≤K_dLess than or equal to 1), adding K_dThe voltage vector allocated to the vector group two and the vector combination is U_ref2Will be (1-K)_d) Is assigned to the vector set one and,vector set-composite voltage vector U_ref1Then the reference voltage vector is represented as

U_ref＝U_ref1+U_ref2(4)

Obtaining a voltage vector expression formed by combining a vector group I and a vector group II from the formula (2)

Preferably, the power distribution on the dc side is implemented by considering that the modulation effects of the vector group one and the vector group two are the same, but the switching states are different, the current influence on the two groups of independent energy sources on the dc side is different, and the vector group one only influences V₂Current i of_dc2Vector set two simultaneous effects V₁Current i of_dc1And V₂Current i of_dc2And i is_dc1＝-i_dc2The dc-side current i can then be divided by the allocation of the time-weighted vector contribution in one switching cycle_dc1、i_dc2And controlling to realize power distribution of two groups of independent energy sources at the direct current side.

Preferably, the acquiring the plurality of energy circulation modes comprises:

the vector group I and the vector group II are mixed and modulated, and the action time proportion distribution of the vector group I and the vector group II is controlled to realize two groups of independent energy sources V on the direct current side₁、V₂Current control of (V)₁、V₂The working mode of the motor is not fixed any more, and more current (energy) circulation modes can be obtained between the motor and the three vehicles, which comprises the following steps:

the first mode is as follows: v₂Auxiliary V₁Simultaneously outputting energy to the three-phase alternating current motor;

and a second mode: v₁Outputting energy to the three-phase alternating current motor independently;

and a third mode: v₂Outputting energy to the three-phase alternating current motor independently;

and a fourth mode: v₁Outputting energy to three-phase AC motor simultaneously to V₂Outputting energy;

and a fifth mode: v₂Auxiliary V₁Absorbing energy from the three-phase AC motor;

mode six: v₁Absorbing energy from the three-phase alternating current motor alone;

mode seven: v₂Absorbing energy from the three-phase alternating current motor alone;

and a mode eight: v₁Absorbing energy from a three-phase ac motor while simultaneously passing from V₂Energy is absorbed.

The invention has the beneficial effects that: three-level output phase voltages are obtained at the alternating current side of the multi-source converter, and the three levels depend on two groups of independent direct current energy sources V at the direct current side₁And V₂The harmonic performance of the output voltage is improved; by a method based on coordinate operation, the problems of small sector judgment and basic vector action time calculation when the midpoint voltage is unbalanced are solved, and the operation amount is reduced; and the vector group I and the vector group II are mixed for modulation, and the action time weight of the vector group I and the vector group II is controlled, so that the power distribution of the direct current side can be realized, and more energy circulation modes can be obtained.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a topology structure diagram of a multi-source converter according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a space vector model of neutral point potential imbalance according to an embodiment of the present invention.

FIG. 3 shows a schematic view of a V according to an embodiment of the present invention₁＜2V₂The vector group I and the vector group II in the time-large sector I divide a small sector schematic diagram.

Fig. 4 is a rectangular coordinate diagram of calculating the action time of the basic small vector according to the embodiment of the present invention.

Fig. 5 is a schematic diagram of a switching sequence of a reference voltage vector modulated by a vector group one and a vector group two in a large sector, a medium sector ② according to an embodiment of the present invention.

Fig. 6 is a schematic step diagram of a multi-source transformer space vector modulation method according to an embodiment of the present invention.

Fig. 7 is a schematic diagram of an energy circulation mode of a multi-source converter according to an embodiment of the invention.

Fig. 8 is a schematic diagram of a multi-source converter topology according to an embodiment of the present invention.

Fig. 9 is a schematic diagram of a single-phase bridge arm topology of a multi-source converter according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below by way of the drawings are illustrative only and are not to be construed as limiting the invention.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

In the description of this patent, it is to be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for the convenience of describing the patent and for the simplicity of description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the patent.

In the description of this patent, it is noted that unless otherwise specifically stated or limited, the terms "mounted," "connected," and "disposed" are to be construed broadly and can include, for example, fixedly connected, disposed, detachably connected, disposed, or integrally connected and disposed. The specific meaning of the above terms in this patent may be understood by those of ordinary skill in the art as appropriate.

For the purpose of facilitating an understanding of the present invention, the present invention will be further explained by way of specific embodiments with reference to the accompanying drawings, which are not intended to limit the present invention.

It should be understood by those skilled in the art that the drawings are merely schematic representations of embodiments and that the elements shown in the drawings are not necessarily required to practice the invention.