CN101515782A - Phase voltage difference value type SVPWM control method for asynchronous motor - Google Patents

Abstract

The invention discloses a phase voltage difference type SVPWM control method for an asynchronous motor; in each PWM control period, the phase voltage difference of the three-phase sinusoidal reference voltage with a phase difference of 120° generated by the control system is used to generate Directly calculate the action time of the basic voltage space vector, and judge the sector position of the circularly rotating reference voltage vector V _ref according to the sequence relationship of the three reference phase voltages arranged from large to small, completely omitting the coordinates in the traditional method Matrix transformation, trigonometric function operation, and vector decomposition and derivation of reference voltage vector to sector, all intermediate processes are simplified to only judge the magnitude sequence of three phase voltages and calculate their difference, the steps are clear, the model is simple, the calculation efficiency is high, and real-time Strong, suitable for high-precision control, and has great theoretical innovation and application value.

Description

The phase voltage difference value type SVPWM control method that is used for asynchronous machine

Technical field

The present invention relates to asynchronous machine frequency conversion control technique field, relate in particular to a kind of phase voltage difference value type SVPWM control method that is used for asynchronous machine that can improve real-time control efficiency.

Background technology

Characteristics such as space vector of voltage pulse-width modulation (SVPWM) technology is few with its switch number of times, voltage utilization is high, the inhibition harmonic wave is effective have been widely used in the asynchronous machine AC variable-frequency speed regulation system.But traditional SVPWM control method at first need be introduced the Park coordinate transform, the V under the three-phase rotating coordinate system _a, V _b, V _cPhase voltage is mapped as the space vector of voltage component under the two-dimentional rest frame, asks for phase angle theta by arc tangent and comes sectorization, and obtain fundamental voltage space vector action time by formula (1):

$\left\{\begin{array}{c}{T}_K=\frac{T_S}{V_{\mathrm{dc}}}\left|V_{\mathrm{ref}}\right|(\cos \mathrm{\θ}-\frac{\sin \mathrm{\θ}}{\sqrt{3}})\\ T_{K+1}=\frac{2}{\sqrt{3}}\·\frac{T_S}{V_{\mathrm{dc}}}\left|V_{\mathrm{ref}}\right|\sin \mathrm{\θ}\end{array}\right.---\left(1\right)$

Seeing Fig. 2, is V0 (000), V1 (100), V2 (110), V3 (010), V4 (011), V5 (001), V6 (101), V7 (111) corresponding to 8 fundamental voltage space vectors of Fig. 1 three-phase inverter, T _k, T _K+1Be respectively under the two-dimentional rest frame adjacent fundamental voltage space vector V in the same sector _k, V _K+1Action time, T _sBe PWM switch periods, V _DcBe Fig. 1 three-phase inverter DC bus-bar voltage, θ is an electrical degree.More than analyze as seen, traditional SVPWM control method need be carried out coordinates matrix conversion, trigonometric function calculating, and software overhead is bigger, and computational efficiency is lower, the real-time of influence control.For remedying these deficiencies, many documents are specialized in this.Coordinate transform has been simplified in some research, but need carry out the unreasonable division and the absolute calculation of trigonometric function; Some has researched and solved irrational number, absolute value problem, the computing formula of fundamental voltage space vector action time is simplified, but the Practical Calculation amount is still bigger; Space vector of voltage component calculating in the two-dimentional rest frame has been simplified in some research, but the parameter matrix of introducing has brought a large amount of trigonometric function operations.Although relevant shortcut calculation is constantly weeded out the old and bring forth the new, still can't overcome that this long drawback that disappears, can not fundamentally solve the bigger problem of amount of calculation.

Summary of the invention

The objective of the invention is at the deficiencies in the prior art, a kind of phase voltage difference value type SVPWM control method that is used for asynchronous machine is provided.

The objective of the invention is to be achieved through the following technical solutions: a kind of phase voltage difference value type SVPWM control method that is used for asynchronous machine, three-phase inverter have three and go up bridge tube U, V, W and three following bridge tube x, y, z; This method may further comprise the steps:

(1), obtains three-phase reference voltage V according to the control requirement of threephase asynchronous machine _a, V _b, V _c

(2) press three-phase reference voltage V _a, V _b, V _cSorted lists is determined reference voltage space vector V from big to small _RefSector position of living in;

(3) the two adjacent fundamental voltage space vector V in the sector that seek common ground respectively _k, V _K+1T action time _k, T _K+1；

(4) by T _k, T _K+1Converse pipe ON time t on the inverter three-phase brachium pontis _Aon, t _Bon, t _Con, correspond respectively to bridge tube U, V, W ON time;

(5) according to the combination and the action time of different sectors fundamental voltage space vector,, make according to predefined frequency and amplitude and carry out the circle rotation, finally realize phase voltage difference value type SVPWM output by controlling this sector three-phase PWM switching mode.

Further, in the described step (3), through type:

$\left\{\begin{array}{c}{T}_K=\frac{T_S}{V_{\mathrm{dc}}}(V_x-V_y)\\ T_{K+1}=\frac{T_S}{V_{\mathrm{dc}}}(V_y-V_z)\end{array}\right.$

Obtain T action time _k, T _K+1, wherein, V _DcBe the three-phase inverter DC bus-bar voltage.

Further, in the described step (4), through type:

$\left\{\begin{array}{c}{t}_{\mathrm{aon}}=\frac{T_s-T_k-T_{k+1}}{2}\\ t_{\mathrm{bon}}=t_{\mathrm{aon}}+T_k\\ t_{\mathrm{con}}=t_{\mathrm{aon}}+T_k+T_{k+1}\end{array}\right.$

Obtain pipe ON time t on the inverter three-phase brachium pontis _Aon, t _Bon, t _Con

The invention has the beneficial effects as follows:

1, presses three with reference to phase voltage V _a, V _b, V _cSorted lists is judged the reference voltage vector V with the circle rotation from big to small _RefSector position of living in is avoided asking for the method that phase angle theta is come sectorization, has improved the output voltage precision.

2, utilize the phase voltage difference (V of the three phase sine reference voltage of 120 ° of phase place mutual deviations that control system generates _a-V _b), (V _a-V _c), (V _c-V _b) directly ask for fundamental voltage space vector action time, avoid complicated calculations such as coordinates matrix conversion, trigonometric function.

Description of drawings

Fig. 1 is three-phase inverter main circuit structure figure;

Fig. 2 is a space vector of voltage effect schematic diagram;

Fig. 3 is space vector of voltage three-phase PWM switching mode schematic diagram when acting on first sector.

Embodiment

Describe the present invention below with reference to the accompanying drawings in detail, it is more obvious that purpose of the present invention and effect will become.

Core of the present invention is: two adjacent fundamental voltage space vector V in the same sector under the two-dimentional rest frame _k, V _K+1T action time _k, T _K+1, be direct three phase voltage difference variable (V according to asynchronous machine _a-V _b), (V _a-V _c), (V _c-V _b) draw, do not relate to coordinates matrix conversion and trigonometric function and calculate.The present invention is an example with first sector, sees Table 1.Table 1: tabulation is judged in space vector of voltage Vref effect sector

V in first sector _a＞V _b＞V _c, then the specific implementation of difference SVPWM is by following T _k, T _K+1Computing formula (2) is carried out:

$\left\{\begin{array}{c}{T}_K=\frac{T_S}{V_{\mathrm{dc}}}(V_a-V_b)\\ T_{K+1}=\frac{T_S}{V_{\mathrm{dc}}}(V_b-V_c)\end{array}\right.---\left(2\right)$

T wherein _sBe PWM switch periods, V _DcBe the three-phase inverter DC bus-bar voltage.In like manner, if reference voltage vector V _RefBe in the 5th sector, V in the 5th sector _c＞V _a＞V _b, T then _k, T _K+1Calculating by formula (3) carry out:

$\left\{\begin{array}{c}{T}_K=\frac{T_S}{V_{\mathrm{dc}}}(V_c-V_a)\\ T_{K+1}=\frac{T_S}{V_{\mathrm{dc}}}(V_a-V_b)\end{array}\right.---\left(3\right)$

Usually, establish certain sector V _x＞V _y＞V _zBe three descending phase voltage orderings, then T _k, T _K+1The calculating general formula see formula (4):

$\left\{\begin{array}{c}{T}_K=\frac{T_S}{V_{\mathrm{dc}}}(V_x-V_y)\\ T_{K+1}=\frac{T_S}{V_{\mathrm{dc}}}(V_y-V_z)\end{array}\right.---\left(4\right)$

As shown in Figure 1, V _DcBe the three-phase inverter DC bus-bar voltage, U, V, W are the last bridge tube of three-phase inverter, and x, y, z are the following bridge tube of three-phase inverter, V _a, V _b, V _cThree phase supply voltage for asynchronous machine.

As shown in Figure 2, V _RefBe reference voltage vector with the circle rotation, 8 fundamental voltage space vectors are respectively V0 (000), V1 (100), V2 (110), V3 (010), V4 (011), V5 (001), V6 (101), V7 (111), whole space vector of voltage is divided into 1～6 six sector, and zero vector V0 (000), V7 (111) are positioned at the hexagon mid point.

As shown in Figure 3, be space vector of voltage three-phase PWM switch pattern example when acting on first sector, its space vector of voltage is distributed as: V ₀V ₁V ₂V ₇V ₂V ₁V ₀The present invention is used for the phase voltage difference value type SVPWM control method of asynchronous machine, may further comprise the steps:

1,, obtains three-phase reference voltage V according to the control requirement of threephase asynchronous machine _a, V _b, V _c

V _a, V _b, V _cGiven according to conditions such as the break frequency voltage of the highest lowest operating frequency, rated voltage and maximum operating voltage, Heng Gongshuaiqu and the Heng Zhuanjuqu of threephase asynchronous machine and maximum operating currenbt amplitude limits.

2, press three-phase reference voltage V _a, V _b, V _cSorted lists is determined reference voltage space vector V from big to small _RefSector position of living in.

Press the listed V of table 1 _a, V _b, V _cOrdering is for example worked as digital processing unit and is determined current V _a＞V _b＞V _c, V then _RefBe in first sector, avoid asking for the method that phase angle theta is come sectorization, the software resource occupancy is low, method is succinct.Determined V _RefSector position of living in just obtains synthetic V _RefRequired this sector adjacent fundamental voltage space vector V _k, V _K+1, as the first sector V _k=V1 (100), V _K+1=V2 (110).

3. two adjacent fundamental voltage space vector V in the sector seek common ground respectively _k, V _K+1T action time _k, T _K+1

Among Fig. 2, as the first sector V _a＞V _b＞V _c, by formula (4) calculate T _k, T _K+1General formula, get x=a, y=b, z=c, when specifically calculating, V _a, V _b, V _cAnd DC bus-bar voltage V _DcMake mark and change processing.

4. by T _k, T _K+1Converse pipe ON time t on the inverter three-phase brachium pontis _Aon, t _Bon, t _Con, correspond respectively to U, V, W ON time.

t _Aon, t _Bon, t _ConCalculating see formula (5), after mark is changed, be equivalent to the built-in three-phase PWM generating unit comparison value of digital processing unit, represent with reference to the phase voltage difference that with three formula (6) is promptly arranged.

$\left\{\begin{array}{c}{t}_{\mathrm{aon}}=\frac{T_s-T_k-T_{k+1}}{2}\\ t_{\mathrm{bon}}=t_{\mathrm{aon}}+T_k\\ t_{\mathrm{con}}=t_{\mathrm{aon}}+T_k+T_{k+1}\end{array}\right.---\left(5\right)$

$\left\{\begin{array}{c}{t}_{\mathrm{aon}}=\frac{T_S}{{2V}_{\mathrm{dc}}}[V_{\mathrm{dc}}-(V_x-V_z)]\\ t_{\mathrm{bon}}=\frac{T_S}{{2V}_{\mathrm{dc}}}[V_{\mathrm{dc}}+(V_x-V_y)+(V_z-V_y)]\\ t_{\mathrm{con}}=\frac{T_S}{{2V}_{\mathrm{dc}}}[V_{\mathrm{dc}}+(V_x-V_z)]\end{array}\right.---\left(6\right)$

5. according to the combination and the action time of different sectors fundamental voltage space vector,, make according to predefined frequency and amplitude and carry out the circle rotation, finally realize phase voltage difference value type SVPWM output by controlling this sector three-phase PWM switching mode.

Shown in Figure 3 is among the embodiment with first sector, and with reference to figure 2, V1 (100) and V2 (110) synthesize current reference voltage space vector V _Ref, the PWM switching mode is divided into three-phase seven segmentations, its fundamental voltage space vector distributes with V0V1V2V7V2V1V0.In a switch periods, establishing V1 (100) action time is T ₁, V2 (110) action time is T ₂, i.e. three-phase PWM pulsewidth difference synthesized reference voltage vector V _Ref, when being high level (111) or low level (000) in Fig. 3 switching mode, there is not the phase voltage difference, only produce the no-voltage space vector.In this sense, the difference of PWM pulsewidth difference causes the fundamental voltage space vector difference of action time, and the difference of vector action time, finally makes the synthesized reference space vector of voltage V of output _RefDifference shows the three-phase voltage that inverter output varies in size.Therefore, the difference of three phase voltages has directly reflected the difference of PWM pulsewidth, this innovative significance of the present invention just place.

The present invention is in each PWM control cycle, utilize the phase voltage difference of the three phase sine reference voltage of 120 ° of phase place mutual deviations that control system generates directly to ask for fundamental voltage space vector action time, judge reference voltage vector V with reference to the phase voltage ordinal relation with the circle rotation by three that arrange from big to small _RefSector position of living in, having omitted coordinates matrix conversion, trigonometric function operation and the reference voltage vector in the conventional method fully derives to the resolution of vectors of sector, all pilot process is reduced to the size order of only judging three phase voltages and calculates its difference, step is clear, model is simple, and the computational efficiency height is real-time, be fit to High Accuracy Control, have bigger theory innovation and using value.

Claims (3)

1. phase voltage difference value type SVPWM control method that is used for asynchronous machine, three-phase inverter have three and go up bridge tube U, V, W and three following bridge tube x, y, z.It is characterized in that this method may further comprise the steps:

(1), obtains three-phase reference voltage V according to the control requirement of threephase asynchronous machine _a, V _b, V _c

(2) press three-phase reference voltage V _a, V _b, V _cSorted lists is determined reference voltage space vector V from big to small _RefSector position of living in.

(3) the two adjacent fundamental voltage space vector V in the sector that seek common ground respectively _k,, V _K+1T action time _k,, T _K+1

(4) by T _k,, T _K+1Converse pipe ON time t on the inverter three-phase brachium pontis _Aon, t _Bon, t _Con, correspond respectively to bridge tube U, V, W ON time.

(5) according to the combination and the action time of different sectors fundamental voltage space vector,, make according to predefined frequency and amplitude and carry out the circle rotation, finally realize phase voltage difference value type SVPWM output by controlling this sector three-phase PWM switching mode.

2. according to the described phase voltage difference value type SVPWM control method that is used for asynchronous machine of claim 1, it is characterized in that, in the described step (3), through type:

$\left\{\begin{array}{c}{T}_K=\frac{T_S}{V_{\mathrm{dc}}}(V_x-V_y)\\ T_{K+1}=\frac{T_S}{V_{\mathrm{dc}}}(V_y-V_z)\end{array}\right.$

Obtain T action time _k,, T _K+1, wherein, V _DcBe the three-phase inverter DC bus-bar voltage.

3. according to the described phase voltage difference value type SVPWM control method that is used for asynchronous machine of claim 1, it is characterized in that, in the described step (4), through type:

$\left\{\begin{array}{c}{t}_{\mathrm{aon}}=\frac{T_s-T_k-T_{k+1}}{2}\\ t_{\mathrm{bon}}=t_{\mathrm{aon}}+T_k\\ t_{\mathrm{con}}=t_{\mathrm{aon}}+T_k+T_{k+1}\end{array}\right.$

Obtain pipe ON time t on the inverter three-phase brachium pontis _Aon, t _Bon, t _Con

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