CN102647101A - Three-level space vector modulation method under multiple coordinate systems - Google Patents

Abstract

The invention relates to a three-level space vector modulation method under multiple coordinate systems and relates to a three-level space vector modulation method applied to a middle/high-voltage inverter and a photovoltaic inverter, and a control system thereof. The control system comprises a power grid interface, a voltage-increasing device, a bus capacitor with a neutral point, a power switch device, a clamping diode, a main control system, a driving system and a three-phase load, and the power switch device form a three-phase bridge arm. The three-level space vector modulation method comprises the following specific operation steps of: a, virtually simulating a middle vector of a three-level space vector on the premise of taking an average value of a neutral point current as zero during a switch period; b, respectively calculating a coordinate of a basic vector including a virtual middle vector in coordinate systems of 30 degrees, 60 degrees, 90 degrees, 120 degrees and 150 degrees; and c, judging sector areas according the characters of a reference voltage space vector in each coordinate system. The three-level space vector modulation method under the multiple coordinate systems has the advantages of small calculation amount, capability of simply and conveniently realizing the level balance of the three-level neutral point, and suitability for multi-level space vector modulation of more than three levels.

Description

3 level space vector modulator approach under a kind of multi-coordinate

Technical field:

The present invention relates to a kind of 3 level space vector modulator approach and control system thereof that is applied to mesohigh frequency converter and photovoltaic DC-to-AC converter, be specifically related to a kind of 3 level space vector modulator approach and pulse generation mechanism thereof based on multi-coordinate.

Background technology:

Because the voltage that is added on the power switch pipe is merely the half the of traditional two-level inverter; Therefore; Neutral-point-clamped (NPC) three-level inverter is suitable in the application of mesohigh frequency conversion drive very much, in recent years, owing to can export than the better voltage and current waveform of two-level inverter (low harmonic content; Low electromagnetic interference), the NPC three-level inverter also progressively is applied to the low-voltage driving field.

The subject matter that the NPC three-level inverter exists is that its neutral point voltage squints easily; Under certain condition; DC side neutral point voltage even meeting big ups and downs; Perhaps continue to be displaced to the degree that inverter can not bear, these situation cause power switch pipe overvoltage or damage easily, and inverter itself also can't operate as normal.The characteristic of power switch pipe and dc capacitor is inconsistent to be one of reason that possibly cause the neutral point voltage skew; This inconsistent characteristic causes the slow but lasting skew of neutral point voltage easily; Some dynamic operation conditions such as acceleration, deceleration and four quadrant running etc. also cause the neutral point voltage skew easily; In this case, neutral point voltage can produce fast significantly skew.

Except the characteristic of inverter itself, the skew of neutral point voltage is also relevant with steady operation condition and the modulation technique of NPC, although most of modulation technique similar qualitatively in output waveform, voltage to neutral then can produce different influences.Output voltage and load current increase and power factor approach 0 and can cause the fluctuation of neutral point voltage to increase gradually equally; Especially; Inverter output voltage is maximum and when zero power factor moved, the fluctuation of the neutral point voltage of inverter was maximum, and these situation can have a strong impact on the output characteristic and the reliability of inverter; Although can reduce the neutral point voltage fluctuation to a certain extent through increasing the dc bus capacitor capacity, this can significantly increase the production cost and the volume of inverter.Therefore, be necessary to select suitable modulating technology and neutral point voltage control technology to come the neutral point voltage offset problem of control inverter.

Can know that through analyzing the middle vector in 27 basic vectors and small vector can exert an influence to neutral point point, and just small vector is just in time opposite to the influence of inverter neutral point current potential with negative small vector; Just be based on this characteristic; The method of control three level NPC inverter neutral point current potentials all is through realizing the action time of adjusting positive and negative small vector, still work as invertor operation under the modulation degree condition with higher, the meeting action time of middle vector dominate at present; Only through adjusting the fluctuation or the skew of all uncontrollable neutral point current potential of positive and negative small vector; Therefore, when modulation degree is higher, can make through the mode of vector in virtual its single switch in the cycle influence to the neutral point current potential be zero, and the condition of this mode is that inverter output three-phase current algebraical sum is zero; Behind the virtual middle vector; Six big sectors that split by big vector will be divided into five little sectors respectively again, add up one to have 30 sectors, and no matter which sector the reference voltage space vector drops in; From its three nearest fundamental space vectors through certain action time and in proper order equal effective neutral point current potentials of control inverter; But this is the weak point of mode, and the judgement of sector is very complicated, and has also increased the complexity of other parts of NPC 3 level space vector modulation algorithm.

Summary of the invention:

The purpose of this invention is to provide 3 level space vector modulator approach and system under a kind of multi-coordinate, its amount of calculation is little, can realize three level neutral point potential balances simply and easily, and is applicable to many level space vector debugging that three level are above.

In order to solve the existing problem of background technology; The present invention adopts following technical scheme: its set of systems becomes: device for power switching, clamping diode, master control system, drive system and the threephase load of the bus capacitor of electrical network interface, increasing apparatus, band neutral point, composition three-phase brachium pontis; The sector judgement of 3 level space vector modulator approach, calculating action time, the arrangement of vector sequence of operation and the calculating of two stage comparator comparison value will be carried out among the CPU in master control system; A ripple mechanism of PWM ripple will be carried out among the FPGA in master control borad; This mode can reduce the operating pressure of CPU; Make it have time enough to accomplish fault detect, communication and system's control wait other functions.

Its concrete operations step is:

A, serve as zero to be prerequisite with the mean value of neutral point current in the switch periods, the middle vector of virtual 3 level space vector;

B, respectively calculate comprise virtual in the coordinate of basic vector in 30 °, 60 °, 90 °, 120 ° and 150 ° of coordinate systems of vector;

C, judge the sector at its place according to the characteristics of reference voltage space vector in each coordinate system;

D, the action time of in 60 ° of coordinate systems, calculating nearest three basic vectors in the sector, reference voltage space vector place respectively, and the mapping relations between each little sector of each little sector of definite A sector, B sector and C sector and D sector, E sector and F sector;

E, confirm the sequence of operation of nearest three basic vectors in the sector, reference voltage space vector place, when in the sector, comprising zero vector, first zero vector (PPP); When in the sector, not comprising zero vector, first positive small vector, in addition; The P state of each brachium pontis can not jump to the N state during ordering; The N state can directly not jump to the P state yet, and the switching between P state and the N state has the O state as transition state, and the characteristics that the basic vector that can draw according to aforesaid way puts in order are that initial state is P state or O state; In the single sampling period, the switch number of times of each IGBT is no more than once;

The sequence of operation of f, three basic vectors is confirmed the concrete comparison value of two time comparators of single-phase brachium pontis, and relatively confirms the on off state of each brachium pontis with triangular wave.

The present invention has following beneficial effect:

1, the multi-coordinate stacking method can significantly reduce the judgement difficulty of sector, reference voltage vector place; And this method is applicable to the space vector modulation technique of any level; For example: only need superpose 60 ° of coordinate systems and 120 coordinate systems of the inverter of two level can be accomplished the sector and judge, the conventional method of three level also only needs 60 ° of coordinate systems and 120 coordinate systems can accomplish the sector to judge.

2, simplified the calculating of action time of nearest triangular vector; Utilize the characteristics of 60 ° of coordinate systems; The calculating of nearest triangular vector action time is arranged under this coordinate system carries out; According to the mapping relations of vector action time in the symmetrical sector, can draw nearest triangular vector computing formula action time of its symmetrical sector through mapping relations after triangular vector computing formula action time recently in a sector.

3, the two-stage time manner of comparison that adopts can be simplified the pulse generation mechanism of three-level inverter, can confirm the on off state of four power switchs of corresponding brachium pontis fast through the two stage comparator and the comparison of triangular wave currency.

Description of drawings:

Fig. 1 is the system construction drawing of NPC inverter of the present invention,

Fig. 2 is the basic output voltage vector figure of the present invention in 30 ° of coordinate systems,

Fig. 3 is the basic output voltage vector figure of the present invention in 60 ° of coordinate systems,

Fig. 4 is the basic output voltage vector figure of the present invention in 90 ° of coordinate systems,

Fig. 5 is the basic output voltage vector figure of the present invention in 120 ° of coordinate systems,

Fig. 6 is the basic output voltage vector figure of the present invention in 150 ° of coordinate systems.

Embodiment:

With reference to Fig. 1-Fig. 6; This embodiment adopts following technical scheme: its set of systems becomes: device for power switching, clamping diode, master control system, drive system and the threephase load of the bus capacitor of electrical network interface, increasing apparatus, band neutral point, composition three-phase brachium pontis; The sector judgement of 3 level space vector modulator approach, calculating action time, the arrangement of vector sequence of operation and the calculating of two stage comparator comparison value will be carried out among the CPU in master control system; A ripple mechanism of PWM ripple will be carried out among the FPGA in master control borad; This mode can reduce the operating pressure of CPU; Make it have time enough to accomplish fault detect, communication and system's control wait other functions.

Its concrete operations step is:

A, serve as zero to be prerequisite with the mean value of neutral point current in the switch periods, the middle vector of virtual 3 level space vector;

B, respectively calculate comprise virtual in the coordinate of basic vector in 30 °, 60 °, 90 °, 120 ° and 150 ° of coordinate systems of vector;

C, judge the sector at its place according to the characteristics of reference voltage space vector in each coordinate system;

D, the action time of in 60 ° of coordinate systems, calculating nearest three basic vectors in the sector, reference voltage space vector place respectively, and the mapping relations between each little sector of each little sector of definite A sector, B sector and C sector and D sector, E sector and F sector;

E, confirm the sequence of operation of nearest three basic vectors in the sector, reference voltage space vector place, when in the sector, comprising zero vector, first zero vector (PPP); When in the sector, not comprising zero vector, first positive small vector, in addition; The P state of each brachium pontis can not jump to the N state during ordering; The N state can directly not jump to the P state yet, and the switching between P state and the N state has the O state as transition state, and the characteristics that the basic vector that can draw according to aforesaid way puts in order are that initial state is P state or O state; In the single sampling period, the switch number of times of each IGBT is no more than once;

The sequence of operation of f, three basic vectors is confirmed the concrete comparison value of two time comparators of single-phase brachium pontis, and relatively confirms the on off state of each brachium pontis with triangular wave.The make comparisons power switch state of each brachium pontis of drawing of time comparator and triangular wave is:

$S_x=\left\{\begin{array}{cc}P& \left(\mathrm{Cnt}{<T}_{x1}\right)\\ O& (T_{x1}<\mathrm{Cnt}{<T}_{x2})\\ N& \left(\mathrm{Cnt}{>T}_{x2}\right)\end{array}\right.$

Wherein Sx is the on off state of four power switchs on the x phase brachium pontis, x ∈ (w), two power switch conductings are referred to as the P state above the brachium pontis for u, v, and middle two conductings are called the O state, below two conductings be called the N state, Cnt is the instantaneous value of triangular wave.

The mould value of vector is 2/3 times of vector mould value in the reality in virtual described in the step (a); In virtual in the phase place of vector and the corresponding reality vector consistent, vector and nearest with it positive small vector and the transformational relation between the negative small vector are in virtual middle vector and the reality:

${\stackrel{\&RightArrow;}{V}}_2^{*}=\frac{1}{3}{\stackrel{\&RightArrow;}{V}}_2+\frac{1}{3}{\stackrel{\&RightArrow;}{V}}_{11}+\frac{1}{3}{\stackrel{\&RightArrow;}{V}}_{10}$

Wherein,

is virtual middle vector;

is vector in the reality;

is positive small vector,

for bearing small vector.

The coordinate of each basic vector of calculating in each coordinate system of describing in the step (b) can calculate its coordinate in other coordinate systems through the Coordinate Conversion form then through at first calculating their coordinates under 90 ° of coordinate systems.Coordinate transformation relation between 90 ° of coordinate systems and 30 °, 60 °, 120 ° and the 150 ° of coordinate systems is:

$\left\{\begin{array}{c}{V}_{g30}=V_{\mathrm{\&alpha;}}-\sqrt{3}{V}_{\mathrm{\&beta;}}\\ V_{h30}=2V_{\mathrm{\&beta;}}\end{array}\right.$

$\left\{\begin{array}{c}{V}_{g60}=V_{\mathrm{\&alpha;}}-\frac{V_{\mathrm{\&beta;}}}{\sqrt{3}}\\ V_{h60}=\frac{2V_{\mathrm{\&beta;}}}{\sqrt{3}}\end{array}\right.$

$\left\{\begin{array}{c}{V}_{g120}=V_{\mathrm{\&alpha;}}+\frac{V_{\mathrm{\&beta;}}}{\sqrt{3}}\\ V_{h120}=\frac{2V_{\mathrm{\&beta;}}}{\sqrt{3}}\end{array}\right.$

$\left\{\begin{array}{c}{V}_{g150}=V_{\mathrm{\&alpha;}}+\sqrt{3}{V}_{\mathrm{\&beta;}}\\ V_{h150}=2V_{\mathrm{\&beta;}}\end{array}\right.$

Wherein, (V _α, V _β) be any coordinate in 90 ° of coordinate systems, (V _G30, V _H30), (V _G60, V _H60), (V _G120, V _H120) and (V _G30, V _H30) be respectively (V _α, the Vx) mapping in 30 °, 60 °, 120 ° and 150 ° of coordinate systems.

Computing formula action time of described nearest three basic vectors of step (d) is:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HSA00000643655000022.png,HSA00000643655000031.png"\; state="\{\{state\}\}">d</figure-callout>}}_1=\frac{(V_g-V_{3g})(V_{2h}-V_{3h})-(V_h-V_{3h})(V_{2g}-V_{3g})}{(V_{1g}-V_{3g})(V_{2h}-V_{3h})-(V_{1h}-V_{3h})(V_{2g}-V_{3g})}\\ {\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HSA00000643655000021.png,HSA00000643655000022.png"\; state="\{\{state\}\}">d</figure-callout>}}_2=\frac{(V_g-V_{3g})(V_{1h}-V_{3h})-(V_h-V_{3h})(V_{1g}-V_{3g})}{(V_{3g}-V_{3g})(V_{1h}-V_{3h})-(V_{2h}-V_{3h})(V_{1g}-V_{3g})}\\ {\mathrm{<figure-callout\; id="3"\; label="d"\; filenames="HSA00000643655000022.png,HSA00000643655000032.png"\; state="\{\{state\}\}">d</figure-callout>}}_3=1-d_1-{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HSA00000643655000021.png,HSA00000643655000022.png"\; state="\{\{state\}\}">d</figure-callout>}}_2\end{array}\right.$

In the formula, (V _1g, V _1h), (V _2g, V _2h) and (V _3g, V _3h) be three basic vectors, (V _g, V _h) be reference vector, d1, d2 and d3 are the duty ratios of three basic vectors in the unit interval.

Because the coordinate of each basic vector of other the vector is integer in virtual under 60 ° of coordinate systems, therefore when calculating the action time of nearest three basic vectors, is generally selected in 60 ° of coordinate systems and carries out.Can form a regular hexagon by the fundamental voltage space vector of inverter; This hexagon is equated by amplitude again; Six fundamental voltage space vectors that the phase place mutual deviation is 120 ° are divided into six big sectors, respectively it are defined as A sector (0 °-60 °), B sector (60 °-120 °), C sector (120 °-180 °), D sector (180 °-240 °), E sector (240 °-300 °) and F sector (300 °-360 °).

Like Fig. 1, the principle of this embodiment is: establish above the single-phase brachium pontis that the state of two shutoffs is the P state below two device for power switching conductings, the state of two two disconnections in device for power switching conducting top and bottom is the O state in the middle of the brachium pontis; Below the brachium pontis above two device for power switching conductings the state of two disconnections be the N state, then a device for power switching always has 3 on off states, three single-phase brachium pontis, 27 basic voltage vectors that go out three-phase inverter capable of being combined altogether; According to the difference of vector mould value, these 27 vectors can be divided into zero vector (V0), positive small vector (V11), negative small vector (V10), middle vector (V2) and big vector (V3) again, according to the modular invariance principle; The mould value of zero vector is 0, and the mould value of small vector is Vdc/3, and the mould value of middle vector is Vdc/; The mould value of big vector is 2Vdc/3, and the sense of current of establishing outflow inverter neutral point is for just, in order to prevent the skew of inverter neutral point current potential; Need guarantee single switch in the cycle average current in of neutral point be zero, under the lower situation of High Power Factor and output modulation degree, inverter neutral point current potential can be effectively controlled; But power factor approach and the modulation degree condition with higher under, inverter neutral point current potential possibly have bigger drift, because the neutral point potential shift that middle vector causes can't obtain full remuneration; Therefore consider a virtual middle vector; The selection principle of vector is the not influence of its alignment current potential in virtual, general virtual in vector be that middle vector and two small vectors by reality combine, the combination back is in a switch periods; Middle vector is identical with the action time of two small vectors; And what three vectors were corresponding respectively is three-phase current, and in general, switch periods is less; Can guarantee the algebraical sum iu+iv+iw=0 of three-phase current in this case, the average current that so just can guarantee neutral point is zero.The mould value of vector is 2/3 times of vector mould value in the reality in virtual, virtual in phase place and the reality of vector vector consistent, the corresponding relation of vector and positive and negative small vector is in virtual middle vector and the reality:

${\stackrel{\&RightArrow;}{V}}_2^{*}=\frac{1}{3}{\stackrel{\&RightArrow;}{V}}_2+\frac{1}{3}{\stackrel{\&RightArrow;}{V}}_{11}+\frac{1}{3}{\stackrel{\&RightArrow;}{V}}_{10}---\left(1\right)$

Wherein,

is virtual middle vector;

is vector in the reality;

is positive small vector,

for bearing small vector.

Can comprise virtual middle vector in the interior Coordinate Conversion of each fundamental voltage space vector under each coordinate system after the distribution of vector in virtual accomplishing, coordinate and the transformational relation 90 ° coordinate system between of each basic vector in 30 °, 60 °, 120 ° and 150 ° of coordinate systems is:

$\left\{\begin{array}{c}{V}_{g30}=V_{\mathrm{\&alpha;}}-\sqrt{3}{V}_{\mathrm{\&beta;}}\\ V_{h30}=2V_{\mathrm{\&beta;}}\end{array}\right.---\left(2\right)$

$\left\{\begin{array}{c}{V}_{g60}=V_{\mathrm{\&alpha;}}-\frac{V_{\mathrm{\&beta;}}}{\sqrt{3}}\\ V_{h60}=\frac{2V_{\mathrm{\&beta;}}}{\sqrt{3}}\end{array}\right.---\left(3\right)$

$\left\{\begin{array}{c}{V}_{g120}=V_{\mathrm{\&alpha;}}+\frac{V_{\mathrm{\&beta;}}}{\sqrt{3}}\\ V_{h120}=\frac{2V_{\mathrm{\&beta;}}}{\sqrt{3}}\end{array}\right.---\left(4\right)$

$\left\{\begin{array}{c}{V}_{g150}=V_{\mathrm{\&alpha;}}+\sqrt{3}{V}_{\mathrm{\&beta;}}\\ V_{h150}=2V_{\mathrm{\&beta;}}\end{array}\right.---\left(5\right)$

Wherein, (V _α, V _β) be any coordinate in 90 ° of coordinate systems, (V _G30, V _H30), (V _G60, V _H60), (V _G120, V _H120) and (V _G30, V _H30) be respectively (V _α, V _β) mapping in 30 °, 60 °, 120 ° and 150 ° of coordinate systems, the coordinate of each basic vector in five coordinate systems is shown in Fig. 2～6.

The judgement of control voltage reference value big sector of living in is comprehensively to judge with 120 ° of coordinate systems through superposeing 60 ° to draw, and sector A, B and C are mapping relations one to one with big sector D, E and F respectively greatly, and concrete big sector basis for estimation is:

The judgement of control voltage reference value little sector of living in then draws through 5 coordinate systems are comprehensively judged; Behind the big sector of judging reference voltage space vector place, can judge the little sector at its place, if reference voltage vector is in the A sector; Then can judge its which little sector in the A sector at the g axle component in 90 °, 120 ° and the 150 ° of coordinate systems through reference voltage vector; Owing to utilize 30 °, 90 °, when 120 ° and 150 ° of coordinate systems are judged, only use g axle component; Therefore in the Coordinate Conversion process of reality, the h axle component of these coordinate systems there is no need to go to calculate again.Concrete little sector basis for estimation is:

Behind the sector of judging the reference voltage vector place, the computing formula of the effect duty ratio of three fundamental voltage space vectors is in this sector:

$\left\{\begin{array}{c}{V}_g=d_1{V}_{1g}+d_2{V}_{2g}+d_3{V}_{3g}\\ V_h=d_1{V}_{1h}+d_2{V}_{2h}+d_3{V}_{3\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HSA00000643655000022.png,HSA00000643655000031.png"\; state="\{\{state\}\}">h</figure-callout>}}\\ {1=\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HSA00000643655000022.png,HSA00000643655000031.png"\; state="\{\{state\}\}">d</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HSA00000643655000021.png,HSA00000643655000022.png"\; state="\{\{state\}\}">d</figure-callout>}}_2+d_3\end{array}\right.---\left(6\right)$

The concrete effect duty ratio computing formula of three fundamental voltage space vectors is:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HSA00000643655000022.png,HSA00000643655000031.png"\; state="\{\{state\}\}">d</figure-callout>}}_1=\frac{(V_g-V_{3g})(V_{2h}-V_{3h})-(V_h-V_{3h})(V_{2g}-V_{3g})}{(V_{1g}-V_{3g})(V_{2h}-V_{3h})-(V_{1h}-V_{3h})(V_{2g}-V_{3g})}\\ {\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HSA00000643655000021.png,HSA00000643655000022.png"\; state="\{\{state\}\}">d</figure-callout>}}_2=\frac{(V_g-V_{3g})(V_{1h}-V_{3h})-(V_h-V_{3h})(V_{1g}-V_{3g})}{(V_{3g}-V_{3g})(V_{1h}-V_{3h})-(V_{2h}-V_{3h})(V_{1g}-V_{3g})}\\ {\mathrm{<figure-callout\; id="3"\; label="d"\; filenames="HSA00000643655000022.png,HSA00000643655000032.png"\; state="\{\{state\}\}">d</figure-callout>}}_3=1-d_1-d_2\end{array}\right.---\left(7\right)$

Can find out through Fig. 3, under 60 ° of coordinate systems, except the coordinate of vector in virtual is the mark; Other basic vectors are absolute value smaller or equal to 2 integer, therefore, adopt 60 ° of coordinate systems the most suitable as the action time of calculating nearest triangular vector; The action time of nearest three basic vectors is as shown in the table, it is to be noted that all need multiply by switch periods Ts the action time of each space vector, and the k value that comprises action time is by the sector decision at reference voltage vector place; In big sector A, B and C; K gets 1, and in big sector D, E and F, k gets-1; Computing formula through in the table can be found out, only needs the action time of each vector simple calculating to draw.

Drawing what implement after action time of nearest three basic vectors is the sequence of operation of the basic vector that in three coordinates, comprised, and output voltage is undergone mutation when switching for fear of the sector, and first zero vector (PPP) is all adopted in A1～F1 sector; First positive small vector is all adopted in other sectors, must guarantee that also the P state of every phase can not jump to the N state during this external ordering, and the N state can directly not jump to the P state yet; Switching between P state and the N state needs the O state as transition state; Can draw putting in order of basic vector in each sector according to aforesaid way, be characterized in that initial state is P state or O state, in the single sampling period; The switch number of times of each IGBT is no more than once; Therefore can be that every phase brachium pontis is set two time comparators, i.e. if ucp1, ucp2, vcp1, vcp2, wcp1 and wcp2 be in the single sampling period; Every phase brachium pontis output state only has the conversion between P state and the O state; Then the value of comparator xcp1 is by decision action time of basic vector, and comparator xcp2 is a value more than or equal to Ts/2 (generally getting Ts), if every phase brachium pontis output state only has the conversion between O state and the N state; It is zero that xcp1 then can be set; The value of comparator xcp2 is by decision action time of basic vector, if every phase brachium pontis output state comprises P state, O state and three states of N state, then the value of comparator xcp1 and xcp2 is by decision action time of basic vector.The definite of the judgement of sector, the calculating of action time and six time comparator values all realizes in MCU (sh7058 of auspicious Sa); The pulse generation mechanism that six time comparators and triangular wave are formed then realizes (cyclone that ALTERA company produces) in FPGA, and guarantees between sx1 and sx3 and sx2 and the sx4 certain Dead Time is arranged.The make comparisons power switch state of each brachium pontis of drawing of time comparator and triangular wave is:

$S_x=\left\{\begin{array}{cc}P& \left(\mathrm{Cnt}{<T}_{x1}\right)\\ O& (T_{x1}<\mathrm{Cnt}{<T}_{x2})\\ N& \left(\mathrm{Cnt}{>T}_{x2}\right)\end{array}\right.---\left(8\right)$

Described Sx is the on off state of four power switchs on the x phase brachium pontis, x ∈ (w), two power switch conductings are referred to as the P state above the brachium pontis for u, v, and middle two conductings are called the O state, below two conductings be called the N state, Cnt is the instantaneous value of triangular wave.

This embodiment amount of calculation is little, can realize three level neutral point potential balances simply and easily, and is applicable to many level space vector debugging that three level are above.

Claims (2)

1. the 3 level space vector modulator approach under the multi-coordinate; The set of systems that it is characterized in that it becomes: device for power switching, clamping diode, master control system, drive system and the threephase load of the bus capacitor of electrical network interface, increasing apparatus, band neutral point, composition three-phase brachium pontis; The sector judgement of 3 level space vector modulator approach, calculating action time, the arrangement of vector sequence of operation and the calculating of two stage comparator comparison value will be carried out among the CPU in master control system, and a ripple mechanism of PWM ripple will be carried out among the FPGA in master control borad.

2. the 3 level space vector modulator approach under a kind of multi-coordinate according to claim 1 is characterized in that its concrete operations step is:

(a), serve as zero to be prerequisite with the mean value of neutral point current in the switch periods, the middle vector of virtual 3 level space vector;

(b), calculate respectively comprise virtual in the coordinate of basic vector in 30 °, 60 °, 90 °, 120 ° and 150 ° of coordinate systems of vector;

(c), judge the sector at its place according to the characteristics of reference voltage space vector in each coordinate system;

(d), action time of in 60 ° of coordinate systems, calculating nearest three basic vectors in the sector, reference voltage space vector place respectively, and mapping relations between each little sector of each little sector of definite A sector, B sector and C sector and D sector, E sector and F sector;

(e), confirm the sequence of operation of nearest three basic vectors in the sector, reference voltage space vector place, when in the sector, comprising zero vector, first zero vector (PPP); When in the sector, not comprising zero vector, first positive small vector, in addition; The P state of each brachium pontis can not jump to the N state during ordering; The N state can directly not jump to the P state yet, and the switching between P state and the N state has the O state as transition state, and the characteristics that the basic vector that can draw according to aforesaid way puts in order are that initial state is P state or O state; In the single sampling period, the switch number of times of each IGBT is no more than once;

(f), the sequence of operation of three basic vectors confirms the concrete comparison value of two time comparators of single-phase brachium pontis, and relatively confirms the on off state of each brachium pontis with triangular wave.

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