CN102969709B - Method for judging three phase voltage vector space locations - Google Patents

Abstract

The invention relates to a method for judging three phase voltage vector space locations and belongs to the technical field of power supply. The method includes that two phase voltage of ea and eb in three phase power supply lines of A, B and C are acquired to be input into a judging circuit with a central processing unit (CPU), the fact that three phase voltage vectors are located in one of twelve vector partitions respectively is obtained according to various mutual relations between the A-phase voltage ea and the B-phase voltage eb which are real-timely acquired, and thereby the three phase voltage vector space locations are rapidly obtained. The method for judging the three phase voltage vector space locations has the advantages that complicated coordinate transformation and arc tangent operation in prior art are prevented, and thereby the response speed and control accuracy of the power supply line are improved.

Description

A kind of three-phase voltage vector spatial position determination methods

Technical field

The present invention relates to a kind of determination methods of electric vector, especially a kind of three-phase voltage vector spatial position determination methods, belongs to power supply technique field.

Background technology

The power supply circuits system of three-phase VSC and so on adopts voltage oriented direct Power Control (VO, DPC) usually, and the general control structure adopting direct voltage outer shroud, power inner ring, its principle as shown in Figure 1.Wherein, direct voltage outer shroud is the direct voltage U that will detect _dcwith DC voltage desired value U _dc ^*difference by output current signal after pi regulator, this current signal is active power desired value P with the product of the direct voltage detected ^*.Power inner ring is in three-phase system, according to instantaneous power theory (" instantaneous power theory and the application in electric adjustment thereof ", (day) red wooden Thai language, (Brazil) Edson, (Brazil) Mao Lisai work; Xu Zhengyi, China Machine Press, 2009.5, chapter 3: instantaneous power theory), by the instantaneous voltage u detected _a, u _b, u _cwith transient current i _a, i _b, i _c, can obtain the estimated value of instantaneous active power P, reactive power Q, its computing formula is as follows:

P＝u _ai _a+u _bi _b+u _ci _c

$Q=\frac{1}{\sqrt{3}}[(u_a-u_b)i_c+(u_b-u_c)i_a+(u_c-u_a)i_b]$

Afterwards by obtain system actual power P, Q respectively with reference power P ^*, Q ^*(for realizing system unit power factor, generally get reactive power desired value Q ^*=0) compare, difference sends into hysteresis comparator, output switching signal S _p, S _q(1: increase meritorious/reactive power; 0: reduce meritorious/reactive power).

Meanwhile, the instantaneous voltage u will detected _a, u _b, u _cthrough the process of AD sampling modulate circuit, then judge the locus of three-phase voltage vector, and the space vector of voltage angle θ that will obtain _iwith the S obtained before _p, S _qtogether as the input of switch list, to obtain the triggering signal S that main circuit controls power electronic device entirely _a, S _band S _c.

In said process, the determination methods of traditional three-phase voltage vector spatial position is the three-phase voltage signal u that will detect _a, u _b, u _ccarry out 3/2 coordinate transform, obtain the voltage signal u under two-phase static coordinate _α, u _β, then utilize arctan function to obtain voltage angle θ, determine the locus of three-phase voltage vector with this, be i.e. sector θ _n.Concrete steps are as follows:

First by u _a, u _b, u _ccarry out 3/2 coordinate transform obtain two-phase static coordinate under voltage signal u _α, u _β:

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]$

Then according to u _α, u _βobtain voltage angle θ:

Finally, the locus of three-phase voltage vector is determined according to voltage angle θ.As shown in Figure 2, space vector of voltage is divided into 12 sectors, determines the locus of three-phase voltage vector according to voltage angle θ.(see Fig. 3)

Such as, account for voltage space vector is at θ ₂in sector.Sector θ _ndetermined by following formula:

$(n-2)\frac{\mathrm{\π}}{6}\≤{\mathrm{\θ}}_n\≤(n-1)\frac{\mathrm{\π}}{6},n=\mathrm{1,2},...12$

As can be seen from said process, traditional three-phase voltage vector spatial position judges must by coordinate transform and arctan function computing, and amount of calculation is large, and algorithm is numerous and diverse.Therefore, the response speed of inevitable influential system and control precision.

Summary of the invention

The object of the invention is to: the shortcoming existed for above-mentioned prior art, propose the three-phase voltage vector spatial position determination methods that a kind of process is simple and direct, thus improve response speed and the control precision of power supply circuits system.

In order to reach above object, three-phase voltage vector spatial position determination methods of the present invention gathers two phase voltage e in A, B, C three-phase power line _a, e _bafter being input to the decision circuitry containing CPU, carry out three-phase voltage vector spatial position judgement as follows:

The first step, judge the A phase voltage e of Real-time Collection _awith B phase voltage e _bwhether be more than or equal to zero, as e _abe more than or equal to zero, and e _bbe less than zero, then carry out second step; As e _a, e _ball be more than or equal to zero, then carry out the 5th step; As e _abe less than zero, and e _bbe more than or equal to zero, then carry out the 6th step; As e _a, e _ball be less than zero, then carry out the 9th step;

Second step, judge e _aabsolute value whether be more than or equal to e _babsolute value, carry out the 3rd step as no, then carry out the 4th step in this way;

3rd step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, as otherwise show that three-phase voltage vector is in [0,30 °); Then show that three-phase voltage vector is in this way [30 °, 60 °), terminate afterwards judge or return the first step;

4th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, then show that three-phase voltage vector is in this way [60 °, 90 °), as otherwise show that three-phase voltage vector is in [90 °, 120 °), terminate afterwards judge or return the first step;

5th step, judge e _awhether be more than or equal to e _b, then show that three-phase voltage vector is in this way [120 °, 150 °), as otherwise show that three-phase voltage vector is in [150 °, 180 °), terminate afterwards judge or return the first step;

6th step, judge e _aabsolute value whether be more than or equal to e _babsolute value, carry out the 7th step as no, then carry out the 8th step in this way;

7th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, as otherwise show that three-phase voltage vector is in [180 °, 210 °); Then show that three-phase voltage vector is in this way [210 °, 240 °), terminate afterwards judge or return the first step;

8th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, then show that three-phase voltage vector is in this way [240 ° 270 °), as otherwise show that three-phase voltage vector is in [270 ° 300 °), terminate afterwards judge or return the first step;

9th step, judge e _awhether be more than or equal to e _b, as otherwise show that three-phase voltage vector is in [300 °, 330 °), then show that three-phase voltage vector is in this way [330 °, 360 °), terminate afterwards judge or return the first step.

The foundation of said method of the present invention is, in theory, and two phase voltage signal e _a, e _bthe locus of three-phase voltage vector can be divided into 12 regions (see Fig. 4).If according to e _a, e _bpositive and negative, 4 large regions, i.e. e can be divided into _a>=0, e _b< 0 is A district; e _a, e _ball be not less than zero for B district; e _a< 0, e _b>=0 is C district; e _a, e _ball be less than zero for D district.Then, with | e _a|, | e _b| size for according to above-mentioned 4 large regions Further Divisions can being become 8 regions, namely in A district, | e _a| < | e _b| be A ₁district, | e _a|>=| e _b| be A ₂district; By that analogy, the locus of three-phase voltage vector is divided into A ₁, A ₂, C ₁, C ₂with 5,6,11,12 totally 8 regions.And according to | e _a|+| e _b| with 1.5 times of phase voltage peak value U _mmagnitude relationship can determine the locus of voltage vector.Because

$\left|e_a\right|+\left|e_b\right|=U_m\left|\sin \mathrm{\&omega;t}\right|+U_m\left|\sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\right|---\left(1\right)$

In formula (1), U _mfor system phase voltage amplitude, in interval 1 and 2, $\mathrm{\&omega;t}\&Element;\left[\begin{array}{cc}2\mathrm{k\&pi;}& 2\mathrm{k\&pi;}+\frac{\mathrm{\&pi;}}{3}\end{array}\right],$ Formula (1) can be written as:

$\begin{array}{c}\left|e_a\right|+\left|e_b\right|=U_m\sin \mathrm{\&omega;t}-U_m\sin (\mathrm{\&omega;t}-\frac{2\mathrm{\&pi;}}{3})\\ =U_m\sin \mathrm{\&omega;t}+\frac{1}{2}{U}_m\sin \mathrm{\&omega;t}+\frac{\sqrt{3}}{2}{U}_m\cos \mathrm{\&omega;t}\\ =\frac{3}{2}{U}_m\sin \mathrm{\&omega;t}+\frac{\sqrt{3}}{2}{U}_m\cos \mathrm{\&omega;t}\\ =\sqrt{3}{U}_m\cos (\mathrm{\&omega;t}-\frac{\mathrm{\&pi;}}{3})\end{array}$

In interval 1, namely $\mathrm{\&omega;t}\&Element;\left[\begin{array}{cc}2\mathrm{k\&pi;}& 2\mathrm{k\&pi;}+\frac{\mathrm{\&pi;}}{6}\end{array}\right]$ Shi You $\left|e_a\right|+\left|e_b\right|\&Element;\left[\begin{array}{cc}\frac{\sqrt{3}}{2}{U}_m& 1.5U_m\end{array}\right);$

In interval 2, namely $\mathrm{\&omega;t}\&Element;\left[\begin{array}{cc}2\mathrm{k\&pi;}+\frac{\mathrm{\&pi;}}{6}& 2\mathrm{k\&pi;}+\frac{\mathrm{\&pi;}}{3}\end{array}\right]$ Shi You $\left|e_a\right|+\left|e_b\right|\&Element;\left[\begin{array}{cc}{1.5U}_m& \sqrt{3}{U}_m\end{array}\right).$

It is visible, | e _a|+| e _b|=1.5U _mit is the separation of interval 1 and interval 2.Therefore, only need to compare | e _a|+| e _b| with 1.5U _msize, can determine that voltage vector is residing interval.As A ₁qu Zhong, | e _a|+| e _b| < 1.5Um is 1st district, | e _a|+| e _b|>=1.5Um is 2nd district; In like manner, A ₂, C ₁, C ₂district is divided into 3,4 respectively; 7,8 and 9,10th district; All the other are (see table 1) by that analogy.

Be understood that, after adopting method of the present invention, gather electric power system instantaneous voltage, just can obtain rapidly the locus of three-phase voltage vector, avoid coordinate transform and the arctangent cp cp operation of prior art complexity, thus improve response speed and the control precision of electric power system.

Accompanying drawing explanation

Below in conjunction with accompanying drawing, the present invention is further illustrated.

Fig. 1 is the electrical block diagram of existing electric power system.

Fig. 2 is space vector of voltage 12 sector schematic diagrames.

Fig. 3 is that prior art three-phase voltage vector spatial position judges block diagram.

Fig. 4 is that three-phase voltage vector is divided into 12 area schematic by two phase voltage signals.

Fig. 5 is supply line's structural representation of one embodiment of the invention.

Embodiment

Embodiment one

The three-phase voltage vector spatial position determination methods of the present embodiment is to adopt the three-phase VSC control system of direct Power Control method.Its control circuit contains master cpu (TMS320F28335) and programmable logic controller (PLC) (EP1C6Q240C8), being sampled by AD, (its physical circuit forms see " measuring design of electronic circuits: a filter section (application from design of filter to lock-in amplifier) " slope person of outstanding talent far away clear for modulate circuit and signal synchronization circuit, Peng Junyi, Science Press, 2006) transmit AC voltage, electric current and DC voltage signal to master cpu, AC voltage signal is transferred to programmable logic controller (PLC) FPGA simultaneously.FPGA exports termination master cpu input, the control output end of master cpu is through drive circuit (" design and research based on the static reacance generator of multilevel converter ", Gao Wei, Institutes Of Technology Of Nanjing's Master's thesis, 2006.6, Fig. 5 .3.1) connect three-phase VSC and entirely control power electronic device---the controlled end of IGBT pipe.

Its main composition module is specific as follows:

1) voltage, current transformer, Hall element: each instrument transformer of AC three-phase voltage, electric current and DC voltage signal access voltage source converter device.Three-phase current signal is converted into voltage signal by instrument transformer, and three-phase alternating voltage and DC voltage signal are dropped to the manageable scope of system.

2) signal synchronization circuit (refers to " measuring design of electronic circuits: a filter section (application from design of filter to lock-in amplifier) " slope person of outstanding talent far away clear, Peng Junyi, Science Press,: adopt synchronous third-order low-pass filter and the zero-crossing comparator three-phase voltage output signal to threephase potential transformer to carry out filtering and synchronous process, and produce square-wave synchronous signal and send to master cpu 2006).

3) AD sampling and signal conditioning circuit (refer to (" Basic Analog Electronics ", Yang Shuanke, Higher Education Publishing House, 2010): carry out sampling and necessary signal condition to the output of threephase potential transformer summation current transformer, and data are outputted to FPGA and master cpu.

4) decision circuitry of voltage vector sector: adopt FPGA (EP1C6Q240C8) to realize, (also can signal directly inquire about the sector judgement table be pre-stored in FPGA) can be judged according to the two-phase voltage signal of input by step, to determine the locus of three-phase voltage vector, and result is sent to master cpu.The FPGA realizing three-phase voltage vector spatial position determination function is the hardware implementing major part of the present embodiment method.

5) master cpu: adopt DSP28335 to realize, is responsible for the realization various information of input being carried out to data processing, electrical parameter calculation and control algolithm.Master cpu is the core that three-phase VSC apparatus control portion is divided.

6) driver module: being responsible for the impulse level that master cpu exports to be converted to is enough to drive three-phase VSC device main circuit entirely to control the pwm signal of power electronic device.

7) main circuit: according to the break-make of each full control power electronic device of pwm signal control main circuit that drive circuit exports, realizing the object of direct Power Control, is the execution part of whole three-phase VSC device.

Be summed up, in the supply line shown in Fig. 5, two phase voltage e in A, B, C three-phase _a, e _binput is containing the FPGA decision circuitry of CPU, decision circuitry carries out three-phase voltage vector spatial position judgement as follows, export three-phase voltage vector phase to master cpu, and three-phase voltage signal is by AD sampling modulate circuit and signal synchronization circuit input master cpu, the output of master cpu connects the controlled end of each full control power electronic device in main circuit by drive circuit, in order to export the on-off switch signal of each full control power electronic device, control the active power of supply line:

The first step, judge the A phase voltage e of Real-time Collection _awith B phase voltage e _bwhether be more than or equal to zero, as e _abe more than or equal to zero, and e _bbe less than zero, then carry out second step; As e _a, e _ball be more than or equal to zero, then carry out the 5th step; As e _abe less than zero, and e _bbe more than or equal to zero, then carry out the 6th step; As e _a, e _ball be less than zero, then carry out the 9th step;

Second step, judge e _aabsolute value whether be more than or equal to e _babsolute value, carry out the 3rd step as no, then carry out the 4th step in this way;

3rd step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, as otherwise show that three-phase voltage vector is in [030 °) (i.e. 1st district shown in Fig. 4); Then show that three-phase voltage vector is in this way [30 ° 60 °) (i.e. 2nd district shown in Fig. 4), terminate afterwards judge or return the first step;

4th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, then show that three-phase voltage vector is in this way [60 °, 90 °) (i.e. 3rd district shown in Fig. 4), as otherwise show that three-phase voltage vector is in [90 °, 120 °) (i.e. 4th district shown in Fig. 4), terminate afterwards judge or return the first step;

5th step, judge e _awhether be more than or equal to e _bthen show that three-phase voltage vector is in this way [120 °, 150 °) (i.e. 5th district shown in Fig. 4), as otherwise show that three-phase voltage vector is in [150 °, 180 °) (i.e. 6th district shown in Fig. 4), terminate afterwards judge or return the first step;

6th step, judge e _aabsolute value whether be more than or equal to e _babsolute value, carry out the 7th step as no, then carry out the 8th step in this way;

7th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, as otherwise show that three-phase voltage vector is in [180 °, 210 °) (i.e. 7th district shown in Fig. 4); Then show that three-phase voltage vector is in this way [210 °, 240 °) (i.e. 8th district shown in Fig. 4), terminate afterwards judge or return the first step;

8th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, then show that three-phase voltage vector is in this way [240 °, 270 °) (i.e. 9th district shown in Fig. 4), as otherwise show that three-phase voltage vector is in [270 °, 300 °) (i.e. 10th district shown in Fig. 4), terminate afterwards judge or return the first step;

9th step, judge e _awhether be more than or equal to e _bas otherwise show that three-phase voltage vector is in [300 °, 330 °) (i.e. 11st district shown in Fig. 4), then show that three-phase voltage vector is in this way [330 °, 360 °) (i.e. 12nd district shown in Fig. 4), terminate afterwards judge or return the first step.

The logical relation of above deterministic process can be reflected by following table:

First the present embodiment obtains DC voltage signal by Hall element, after AD sampling and signal conditioning circuit, send into master cpu.In addition, the system voltage sampled signal table look-at received according to FPGA obtains the locus θ of three-phase voltage vector _n, and sent into master cpu.Then, master cpu carries out related operation according to the input signal of modules, obtain the locus etc. of system reference active-power P *, actual active-power P and reactive power Q and three-phase voltage vector, and complete further data processing and system synchronization, export control signal, and the full control power electronic device of three-phase VSC is triggered by drive circuit, reach the object of control system power output.

The three-phase voltage vector spatial position determination methods of the present embodiment only needs two phase voltage signals according to detecting, by the comparison of finite steps, accurately can judge the locus of three-phase voltage vector, without the need to carrying out complicated coordinate transform and arctan function computing, enormously simplify deterministic process, and accuracy of judgement, real-time is good, is easy to realize.Because the corresponding relation of reflection sampled voltage signal and three-phase voltage vector spatial position can adopt form offline design, and related data is stored in advance in master cpu, therefore, according to the signal table look-at detected in real time, the locus of three-phase voltage can be determined completely during actual use.

Claims (3)

1. a three-phase voltage vector spatial position determination methods, is characterized in that gathering two phase voltage e in A, B, C three-phase power line _a, e _binput, containing after the decision circuitry of CPU, carries out three-phase voltage vector spatial position judgement as follows:

The first step, judge the A phase voltage e of Real-time Collection _awith B phase voltage e _bwhether be more than or equal to zero, as e _abe more than or equal to zero, and e _bbe less than zero, then carry out second step; As e _a, e _ball be more than or equal to zero, then carry out the 5th step; As e _abe less than zero, and e _bbe more than or equal to zero, then carry out the 6th step; As e _a, e _ball be less than zero, then carry out the 9th step;

Second step, judge e _aabsolute value whether be more than or equal to e _babsolute value, carry out the 3rd step as no, then carry out the 4th step in this way;

3rd step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, as otherwise show that the argument of three-phase voltage vector is in [0,30 °); Then show that the argument of three-phase voltage vector is in this way [30 °, 60 °), terminate afterwards judge or return the first step;

4th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, then show that the argument of three-phase voltage vector is in this way [60 °, 90 °), as otherwise show that the argument of three-phase voltage vector is in [90 °, 120 °), terminate afterwards judge or return the first step;

5th step, judge e _awhether be more than or equal to e _b, then show that the argument of three-phase voltage vector is in this way [120 °, 150 °), as otherwise show that the argument of three-phase voltage vector is in [150 °, 180 °), terminate afterwards judge or return the first step;

6th step, judge e _aabsolute value whether be more than or equal to e _babsolute value, carry out the 7th step as no, then carry out the 8th step in this way;

7th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, as otherwise show that the argument of three-phase voltage vector is in [180 °, 210 °); Then show that the argument of three-phase voltage vector is in this way [210 °, 240 °), terminate afterwards judge or return the first step;

8th step, judge e _aand e _bwhether absolute value sum is more than or equal to 1.5 times of phase voltage amplitude, then show that the argument of three-phase voltage vector is in this way [240 °, 270 °), as otherwise show that the argument of three-phase voltage vector is in [270 °, 300 °), terminate afterwards judge or return the first step;

9th step, judge e _awhether be more than or equal to e _b, as otherwise show that the argument of three-phase voltage vector is in [300 °, 330 °), then show that the argument of three-phase voltage vector is in this way [330 °, 360 °), terminate afterwards judge or return the first step.

2. three-phase voltage vector spatial position determination methods according to claim 1, it is characterized in that: the amplitude of described decision circuitry output three-phase voltage vector and argument are to master cpu, the three-phase voltage signal of described three-phase power line is by AD sampling modulate circuit and signal synchronization circuit input master cpu, the output of described master cpu connects the controlled end of each full control power electronic device in main circuit by drive circuit, in order to export the on-off switch signal of each full control power electronic device, control the active power of supply line.

3. three-phase voltage vector spatial position determination methods according to claim 2, it is characterized in that: described signal synchronization circuit adopts synchronous third-order low-pass filter and the zero-crossing comparator three-phase voltage output signal to threephase potential transformer to carry out filtering and synchronous process, and produce square-wave synchronous signal and send to master cpu.