阅读说明：本技术 任意多电平的级联h桥逆变器空间矢量脉宽调制方法 (The Cascade H bridge inverter space vector width pulse modulation method of any more level ) 是由 史婷娜 姚欢 阎彦 张国政 王志强 夏长亮 于 2019-08-26 设计创作，主要内容包括：本发明公开了一种任意多电平的级联H桥逆变器空间矢量脉宽调制方法。将多电平空间矢量图进行重新划分,并通过判断参考矢量所处位置直接得到最近三矢量的坐标,将参考矢量等效为附加矢量计算得到最近三矢量的占空比；并且通过零序分量和坐标变换得到开关状态,合成所期望的参考矢量,进行SVPWM调制。本发明实现了在直角坐标系下的任意多电平调制,不需任何迭代计算,且计算量与电平数无关；简化了参考矢量定位以及占空比的计算过程,降低了计算复杂度。(The invention discloses a kind of Cascade H bridge inverter space vector width pulse modulation methods of any more level.Multilevel space vector figure is repartitioned, and by judging that reference vector present position directly obtains the coordinate of nearest three vector, reference vector is equivalent to the duty ratio that nearest three vector is calculated in additional vector quantity；And switch state is obtained by zero-sequence component and coordinate transform, synthesizes desired reference vector, carries out SVPWM modulation.The present invention realizes any Multilevel modulation under rectangular coordinate system, is not required to any iterative calculation, and calculation amount is unrelated with level number；The calculating process for simplifying reference vector positioning and duty ratio, reduces computation complexity.)

1. a kind of Cascade H bridge inverter space vector width pulse modulation method of any more level, method include:

1) the multilevel space vector figure under rectangular coordinate system is drawn by Cascade H bridge inverter voltage vector generated, wherein Interconnecting line constitutes multiple triangles between neighboring voltage vector, and reference vector is in multilevel space vector figure；It is special Sign is that method further includes following steps:

2) the multilevel space vector figure of rectangular coordinate system is carried out dividing two class rectangles, and judges which class square reference vector is in In shape:

The horizontal segmentation dotted line that 4n+1 item is parallel to horizontal axis is added at equal intervals along vertical axis direction, and horizontal segmentation dotted line is flat Row is in α axis direction, and an intermediate horizontal segmentation dotted line and horizontal overlapping of axles, adjacent level divide spacing between dotted line and beA unit length；It adds the vertical segmentation dotted line that 8n-1 item is parallel to vertical axis direction at equal intervals along horizontal axis, erects Straight segmentation dotted line is parallel to β axis direction, and an intermediate vertical segmentation dotted line and vertical overlapping of axles, adjacent upright divide dotted line Between spacing be 0.5 unit length；Wherein, the number of n mutually cascade H-bridge unit each for Cascade H bridge inverter；Unit Length refers in rectangular coordinate system the distance between (1,0) or coordinate (0,1) from origin to coordinate；

Multilevel space vector figure is divided multiple rectangles by horizontal segmentation dotted line and vertical segmentation dotted line, on each rectangle It is located at angular vertex there are two voltage vector, the line between two voltage vectors constitutes a diagonal line of rectangle, root Rectangle is divided into two classes according to rectangle cornerwise difference: the rectangle that angle is 60 degree between diagonal line and α axis direction is as A Class rectangle, the rectangle that angle is 120 degree between diagonal line and α axis direction is as B class rectangle；Finally according to A class rectangle/B The boundary of class rectangle judges that reference vector is in A class rectangle or B class rectangle；

It 3) is I type region by the region in rectangle above diagonal line, by square according to the diagonal line of rectangle by rectangle further division Region in shape below diagonal line is II type region, then judges that reference vector is in I type region or II type region；Further according to A Class/B class rectangle and the division of I type/II type region, the location of reference vector have tetra- class of AI, AII, BI and BII；

4) coordinate of nearest three vector under rectangular coordinate system is obtained according to the location of reference vector, passes through selection zero later Order components simultaneously are coordinately transformed to obtain the switch state of Cascade H bridge inverter；

5) reference vector is decomposed into effective vector OP and additional vector quantity PS, it is nearest in different location that processing obtains reference vector The duty ratio of three vector action times；

6) it is synthesized by the duty ratio of the switch state of Cascade H bridge inverter and nearest three vectors action time desired with reference to arrow Amount realizes that SVPWM is modulated using the reference vector of synthesis.

2. the Cascade H bridge inverter space vector width pulse modulation method of any more level according to claim 1, feature It is: in the step 2), after carrying out the multilevel space vector figure of rectangular coordinate system to divide two class rectangles, judges to refer to Which class rectangle vector is in specifically:

It is calculated using the following equation trunnion axis quantizing factor q first_αWith vertical axes quantizing factor q_βIt is respectively as follows:

In formula, V_refαAnd V_refβRespectively reference vector V_refTrunnion axis and vertical axis component in rectangular coordinate system；floor(·) Indicate downward bracket function；

Then judge to obtain A class rectangle or B class rectangle at reference vector by following formula:

In formula, k_recFor the rectangle coefficient of determination for determining rectangle locating for reference vector；Work as k_recWhen equal to 0, reference vector is in A class In rectangle；Work as k_recWhen equal to 1, reference vector is in B class rectangle.

3. the Cascade H bridge inverter space vector width pulse modulation method of any more level according to claim 1, feature It is: in the step 3), judges that reference vector is in I type region or II type region specifically:

Reference vector V_refIt is decomposed into the synthesis of effective vector OP and additional vector quantity PS, additional vector quantity PS is indicated are as follows:

In formula, v_sα、v_sβTrunnion axis and vertical axis component of the respectively additional vector quantity PS in rectangular coordinate system；

Then judge to obtain the I type region or II type region in rectangle at reference vector by following formula:

In formula, k_regFor the regional determination coefficient for determining region locating for reference vector；Work as k_regWhen greater than 0, reference vector is in I type Region；Work as k_regWhen less than 0, reference vector is in II type region；k_regWhen equal to 0, reference vector is in I type and II type region Boundary can arbitrarily be determined as I type region or II type region.

4. the Cascade H bridge inverter space vector width pulse modulation method of any more level according to claim 1, feature It is: in the step 4), according to the corresponding relationship of such as following table, nearest three vector is obtained according to the location of reference vector and is existed Coordinate under rectangular coordinate system:

Wherein, v₁、v₂And v₃Indicate nearest three vector.

5. the Cascade H bridge inverter space vector width pulse modulation method of any more level according to claim 1, feature Be: in the step 5), processing obtains the duty ratio of reference vector nearest three vectors action time in different location, specifically Are as follows:

When reference vector is located at the position in the region AI or the region BI, the duty ratio of nearest three vector is obtained using following formula:

When reference vector is located at the position in the region AII or the region BII, the duty of nearest three vector is obtained using following formula Than:

In formula, d₁、d₂、d₃Respectively nearest three vectors v₁、v₂And v₃Duty ratio.

Technical field

The present invention relates to a kind of modulator approaches for the Cascade H bridge inverter for belonging to power electronic circuit control field, especially It is a kind of Cascade H bridge inverter space vector pulse width modulation (SVPWM) method of any more level, is suitable for cascaded H-bridges inversion Device is in fields such as electric machine speed regulation, renewable energy power generations.

Background technique

As power electronic technique is in mesohigh, the continuous development of large-power occasions, traditional two-level inverter has been difficult to It is applicable in.Therefore multi-electrical level inverter is in, high-power power transformation field has obtained more and more extensive concern and research.Its In, Cascade H bridge inverter has the characteristics that modular, and required power device is few, the problem of pressure there is no DC bus capacitor, and And it is highly susceptible to the extension of level number, the inverter is widely applied in industrial occasions in these advantages.For the tune of inverter System strategy mainly has carrier modulation (SPWM), and nearest level modulation (NVL), particular harmonic eliminates modulation (SHE) and space vector It modulates (SVPWM).Wherein space vector modulation has bigger modulation flexibility and freedom degree, and is easy to Digital Realization, because But a kind of ideal modulation strategy.But with the increase of level number, for reference vector position in space vector modulation Determining can be extremely complex, and then brings difficulty to nearest three phasor coordinate of determination.In addition, the duty ratio to nearest three vector calculates It also can be more complicated.At this point, the modulator approach in traditional two level or three-level inverter has not been available.

The modulator approach of existing multi-electrical level inverter mainly has three classes according to the difference of coordinate system.The first kind is sat based on abc Mark system, this kind of modulation strategy is using less.Second class is based on 60 degree of coordinate systems, and such method usually requires additional coordinate and turns It changes.Third class is then based on α β coordinate system, but the realization process of existing method is often complex.Certain methods are determining with reference to arrow Level number is depended on when measuring position, needs to be iterated operation, when level number increases, calculation amount can also increase therewith.It is another A little methods then need the trigonometric function operation of sector judgement and complexity, to increase computation complexity.

Summary of the invention

In order to solve the technical problems in background technology, the present invention provides a kind of simple possible, universality are good SVPWM method suitable for Cascade H bridge inverter under any level number.The present invention determines that reference vector institute is in place first It sets, then selects three voltage vectors nearest apart from it, i.e., nearest three phasor coordinate finally calculates three voltage vectors and makees With the duty ratio of time, and then switch state is combined to synthesize desired reference vector, realizes space vector pulse width modulation (SVPWM)。

The technical scheme adopted by the invention is that:

1) more level sky under rectangular coordinate system (α β coordinate system) is drawn by Cascade H bridge inverter voltage vector generated Between polar plot, wherein interconnecting line constitutes multiple triangles between neighboring voltage vector, on three vertex of a triangle Voltage vector be nearest three vector (NTVs), reference vector is in multilevel space vector figure；It is characterized in that, method is also Include the following steps:

2) the multilevel space vector figure of rectangular coordinate system (the α β coordinate system of such as Fig. 2) is carried out dividing two class rectangles, and Judge which class rectangle reference vector is in:

Add the horizontal segmentation dotted line that 4n+1 item is parallel to horizontal axis at equal intervals along vertical axis direction (β axis direction), Horizontal segmentation dotted line is parallel to α axis direction, and an intermediate horizontal segmentation dotted line is overlapped, adjacent level with trunnion axis (α axis) Spacing is between segmentation dotted lineA unit length；8n-1 item is added at equal intervals along horizontal axis (α axis direction) to be parallel to The vertical segmentation dotted line of vertical axis direction, vertical dotted line of dividing are parallel to β axis direction, and an intermediate vertical segmentation dotted line with Vertical axes (β axis) are overlapped, and it is 0.5 unit length that adjacent upright, which divides spacing between dotted line,；Wherein, n is Cascade H bridge inverter Each phase cascade H-bridge unit number；Unit length refers in rectangular coordinate system (1,0) or coordinate from origin to coordinate The distance between (0,1)；

Multilevel space vector figure, which is divided multiple rectangles, by horizontal segmentation dotted line and vertical segmentation dotted line (will be located at side The right angled triangle of edge, which also supplements, regards a rectangle as.), it is located at angular vertex there are two voltage vector on each rectangle, Line between two voltage vectors constitutes a diagonal line of rectangle, is divided into rectangle according to the cornerwise difference of rectangle Two classes: the rectangle that angle is 60 degree between diagonal line and α axis direction as A class rectangle, diagonal line and α axis direction it Between angle be 120 degree rectangle as B class rectangle；Finally judge that reference vector is in A according to A class rectangle/B class rectangle boundary In class rectangle or B class rectangle；

It 3) is I type region by the region in rectangle above diagonal line according to the diagonal line of rectangle by rectangle further division, It is II type region by the region in rectangle below diagonal line, then judges that reference vector is in I type region or II type region；Root again According to A class/B class rectangle and the division of I type/II type region, the location of reference vector has tetra- class of AI, AII, BI and BII；AI, AII, BI and BII respectively indicate the I type region in A class rectangle, the II type region in A class rectangle, the I type region in B class rectangle, II type region in B class rectangle.

4) coordinate of nearest three vector under rectangular coordinate system (α β coordinate system) is obtained according to the location of reference vector, Later by selecting zero-sequence component and being coordinately transformed to obtain the switch state of Cascade H bridge inverter；

5) reference vector is decomposed into effective vector OP and additional vector quantity PS, processing obtains reference vector in different location The duty ratio of nearest three vectors action time；

The solution of nearest three vector duty cycle is equivalent to by the present invention solves additional vector quantity PS accounting in corresponding triangle Empty ratio, the duty ratio for nearest three vectors action time of acquiring reference vector accordingly in different location.

6) desired ginseng is synthesized by the duty ratio of the switch state of Cascade H bridge inverter and nearest three vectors action time Vector is examined, realizes that SVPWM is modulated using the reference vector of synthesis.

In the step 2), after the multilevel space vector figure of rectangular coordinate system is carried out to divide two class rectangles, judgement Which class rectangle reference vector is in specifically:

It is calculated using the following equation trunnion axis quantizing factor q first_αWith vertical axes quantizing factor q_βIt is respectively as follows:

In formula, V_refαAnd V_refβRespectively reference vector V_refIn the trunnion axis and vertical axes (α and β axis) point of rectangular coordinate system Amount；Floor () indicates downward bracket function；

Then judge to obtain A class rectangle or B class rectangle at reference vector by following formula:

In formula, k_recFor the rectangle coefficient of determination for determining rectangle locating for reference vector；Work as k_recWhen equal to 0, at reference vector In A class rectangle；Work as k_recWhen equal to 1, reference vector is in B class rectangle.

In the step 3), judge that reference vector is in I type region or II type region specifically:

Reference vector V_refIt is decomposed into the synthesis of effective vector OP and additional vector quantity PS, according to additional vector quantity PS starting point Coordinate, additional vector quantity PS are indicated are as follows:

In formula, v_sα、v_sβTrunnion axis and vertical axes (α the and β axis) component of respectively additional vector quantity PS in rectangular coordinate system；

Then judge to obtain the I type region or II type region in rectangle at reference vector by following formula:

In formula, k_regFor the regional determination coefficient for determining region locating for reference vector；Work as k_regWhen greater than 0, at reference vector In I type region；Work as k_regWhen less than 0, reference vector is in II type region；k_regWhen equal to 0, reference vector is in I type and II type The boundary in region can arbitrarily be determined as I type region or II type region, not influence on final result.

The present invention judges region equivalent locating for reference vector in any rectangle to judge area locating for additional vector quantity PS Domain, and then obtain region locating for reference vector.

In the step 4), according to the corresponding relationship of such as following table, nearest three arrow is obtained according to the location of reference vector Measure the coordinate under rectangular coordinate system (α β coordinate system):

Wherein, v₁、v₂And v₃It indicates nearest three vector, specifically respectively indicates first voltage vector, second voltage vector, Three voltage vectors.

In the step 5), processing obtains the duty ratio of reference vector nearest three vectors action time in different location, Specifically:

When reference vector is located at the position in the region AI or the region BI, the duty of nearest three vector is obtained using following formula Than:

When reference vector is located at the position in the region AII or the region BII, accounting for for nearest three vector is obtained using following formula Empty ratio:

In formula, d₁、d₂、d₃Respectively nearest three vectors v₁、v₂And v₃Duty ratio.

The beneficial effects of the present invention are:

The SVPWM method for being suitable for Cascade H bridge inverter under any level number of the invention, realizes in α β coordinate Any Multilevel modulation under system, nearest three phasor coordinate are directly obtained by reference vector, are not required to any iterative calculation, and calculate It measures unrelated with level number.

The present invention need to only judge additional vector quantity region locating in rectangle by the way that reference vector is equivalent to additional vector quantity And duty ratio of the additional vector quantity in corresponding triangle, to simplify reference vector positioning and the calculating of duty ratio Journey does not need trigonometric function calculating, reduces computation complexity.

Method of the invention can be applied to the fields such as electric machine speed regulation, renewable energy power generation.

Detailed description of the invention

Fig. 1 is the topology diagram of Cascade H bridge inverter；

Fig. 2 is three dimensional vector diagram and rectangular partition figure under α β coordinate system；

Fig. 3 is reference vector localization method schematic diagram；

Fig. 4 a is the line voltage waveform diagram of when each phase of inverter has 1 H-bridge unit (three level)；

Fig. 4 b is the line voltage waveform diagram of when each phase of inverter has 2 H-bridge units (five level)；

Fig. 4 c is the line voltage waveform diagram of when each phase of inverter has 3 H-bridge units (seven level)；

Fig. 4 d is the line voltage waveform diagram of when each phase of inverter has 4 H-bridge units (nine level).

Specific embodiment

Below with reference to example and attached drawing to the SVPWM method for being suitable for cascaded H-bridges under any level number of the invention It is described in detail.

The topological structure of Cascade H bridge inverter is as shown in Figure 1.Only has 1 H-bridge unit with each phase of Cascade H bridge inverter It is illustrated for (three level), it should be noted that the present invention is suitable for any more level.It is made of at this time voltage vector 3 level space vector figure is as shown in Figure 2 under α β coordinate system.

The SVPWM modulated process of the embodiment of the present invention, includes the following steps: