CN101442255B - Three-phase/biphase coordinates conversion method for frequency changer - Google Patents

Abstract

The invention provides a three-phase/two-phase coordinate conversion method for a frequency converter. The conversion method can convert three phase voltage signals (Ua, Ub, and Uc) under a static coordinate system into two phase voltage signals (VD+ and VQ+) under the static coordinate system by the following steps: step one, two phase voltage signals, namely the Ua and the Ub and two phase voltage signals, namely the Ub and the Uc are subjected to differential proportion operation respectively; step two, the voltage signals which finish the differential proportion operation in step one are subjected to in-phase proportion operation and in-phase summation proportion operation respectively; and step three, the voltage signals which finish an operation result in step two output the two phase voltage signals, namely the VD+ and the VQ+ under the static coordinate system. The method utilizes an electronic circuit to solve the problem that the three phase voltage signals under the static coordinate system are equivalently transformed into the two phase voltage signals under the static coordinate system, saves the resource of a central processing unit, and improves the real-time processing capacity of the central processing unit of the frequency converter.

Description

Be used in the three-phase/two-phase coordinate transformation method on the frequency converter

Technical field

The present invention relates to a kind of three-phase/two-phase coordinate transformation method, especially a kind of three-phase/two-phase coordinate transformation method that is used on the frequency converter.

Background technology

In the industrial frequency transformer technology, two phase voltage signals with under the equivalence of the three-phase voltage signal under the rest frame convert to static coordinate system normally adopt software mode conversion.In frequency converter, generally utilize central processing unit DSP that three-phase voltage signal is handled.Because central processing unit DSP need handle the multi-mode operation task in real time by programming, work such as generation as the collection of a plurality of signals such as power synchronization signal, current signal and bus voltage signal, computing, communication, PWM ripple, take the most of resource of DSP, therefore, frequency converter is very high to the processing capability in real time requirement of DSP, and the improvement of the processing capability in real time of DSP usually is to set about from the performance of DSP own, as increasing multiprocessing system, but its technical difficulty is very high, and the cost of input is also very high.And utilize the electronic circuit method is to improve the circuitous solution route of central processing unit DSP processing capability in real time, and this method can be saved the resource of central processing unit DSP, improve system implementation, improve the response speed of frequency converter.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of central processing unit resource that do not take, and can improve the transform method of the three-phase voltage signal of central processing unit processing capability in real time.

For solving the problems of the technologies described above, the invention provides a kind of three-phase/two-phase coordinate transformation method that is used on the frequency converter, described transform method can be with U with following step _a, U _b, U _cVoltage signal is converted to voltage signal under VD+ and the VQ+ two-phase rest frame under the three phase static coordinate system: step 1: with U _aU _bTwo phase voltage signals and U _bU _cTwo phase voltage signals carry out the difference scale operation respectively; Step 2:, carry out in-phase proportion computing and homophase summation scale operation respectively with the difference scale operation voltage signal that step 1 is finished; Step 3: voltage signal VD+ and VQ+ under the voltage signal output two-phase rest frame of completing steps two operation results.

As a further improvement on the present invention, described difference scale operation is finished in difference ratio arithmetic unit, and described in-phase proportion computing is finished in the in-phase proportion arithmetic unit, and described homophase summation operation is finished in homophase summation operation device.

As another kind of improvement the of the present invention, at U _aU _bTwo phase voltage signals and U _bU _cConnect respectively between two phase voltage signals by a forward diode and the input protection circuit that backward diode is formed, this input protection circuit can prevent the too big damage operational amplification circuit of difference ratio arithmetic unit input terminal voltage difference.

Beneficial effect of the present invention is:

1, utilize electronic circuit to solve with two phase voltage signal problems under the equivalence of the three-phase voltage signal under the rest frame convert to static coordinate system;

2, saved the resource of central processing unit, improved the processing capability in real time of frequency converter central processing unit, improve system implementation, improve the response speed of frequency converter.

Description of drawings

Be described in further detail below in conjunction with accompanying drawing and the specific embodiment of the present invention:

Fig. 1 is the theory diagram of three-phase of the present invention/two-phase coordinate transformation method;

Fig. 2 is that the three-phase voltage waveform transformation is the two-phase voltage oscillogram under the rest frame of the present invention;

Fig. 3 is a two-phase voltage oscillogram under the rest frame of the present invention.

Embodiment

Fig. 1 is the theory diagram of three-phase of the present invention/two-phase coordinate transformation method.Three-phase of the present invention/two-phase coordinate transformation method is to adopt the method for difference scale operation, in-phase proportion computing and homophase summation operation to finish U under the rest frame _a, U _b, U _cThree-phase voltage signal is converted to voltage signal under VD+ and the VQ+ two-phase rest frame.This method is divided following steps: step 1: with U _aU _bTwo phase voltage signals and U _bU _cTwo phase voltage signals carry out the difference scale operation respectively; Step 2:, carry out in-phase proportion computing and homophase summation scale operation respectively with the difference scale operation voltage signal that step 1 is finished; Step 3: voltage signal VD+ and VQ+ under the voltage signal output two-phase rest frame of completing steps two operation results.

The mode of utilization theoretical calculate proves that said method can finish under the rest frame two phase voltage signals under the three-phase voltage signal convert to static coordinate system below.The three-phase voltage signal equation of supposing input is:

$\left\{\begin{array}{c}{U}_a=U_m\cos \mathrm{\ωt}\\ U_b=U_m\cos (\mathrm{\ωt}-2\mathrm{\π}/3)\\ U_c=U_m\cos (\mathrm{\ωt}+2\mathrm{\π}/3)\end{array}\right.$

Adopt the space coordinate transformation method, above-mentioned equation is transformed in the two-phase rest frame, its transformation matrix is:

$T_{\mathrm{DQ}/\mathrm{abc}}=\frac{2}{3}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]$

Transformation equation is:

$\left[\begin{array}{c}\mathrm{VD}+\\ \mathrm{VQ}+\end{array}\right]=\left[T_{\mathrm{DQ}/\mathrm{abc}}\right]\left[\begin{array}{c}{U}_a\\ U_b\\ U_c\end{array}\right]$

With above-mentioned equation and matrix computations:

VD+＝2/3[U _mcosωt-1/2U _mcos(ωt-2/3π)-1/2U _mcos(ωt+2/3π)]

＝2/3U _mcosωt-1/3U _mcos(ωt-2/3π)-1/3U _mcos(ωt+2/3π)

＝U _mcosωt

As seen VD+ and U _aIt is homophase.

VQ+＝2/3[0.866U _mcos(ωt-2/3π)-0.866U _mcos(ωt+2/3π)]

＝0.289U _mcos(ωt-2/3π)-0.289U _mcos(ωt+2/3π)

＝U _msinωt

Therefore, the combinatorial operation of three-phase voltage signal by difference ratio arithmetic unit U3B, in-phase proportion arithmetic unit U3C, difference ratio arithmetic unit U3A and homophase summation operation device U3D can obtain two phase voltage signal VD+ and VQ+ under the rest frame under the rest frame.

Learn that from theoretical calculate this method has just in time realized the three-phase voltage signal (U under the three phase static coordinate system _a, U _b, U _c) the conversion of voltage signal (VD+ and VQ+) under the two-phase rest frame.Can referring to figs. 2 and 3.

A, B, C are respectively the three-phase voltage signals of input among Fig. 2; VD+ is the D shaft voltage signals of output.

VD+ and VQ+ are respectively the D axle and the Q shaft voltage signals of output among Fig. 3, and phase place just in time differs 90 degree.

The realization of three-phase of the present invention/two-phase coordinate transformation method is finished in arithmetic unit, that is to say, described difference scale operation is finished in difference ratio arithmetic unit, described in-phase proportion computing is finished in the in-phase proportion arithmetic unit, and described homophase summation operation is finished in homophase summation operation device.

In order to prevent the too big damage operational amplification circuit of difference ratio arithmetic unit input terminal voltage difference, add an input protection circuit between two phase voltages among the present invention, the composition of this input protection circuit is at U _aU _bTwo phase voltage signals and U _bU _cConnect a forward diode and a backward diode between two phase voltage signals respectively.

The present invention is not limited to above-mentioned embodiment, and every conspicuous technology distortion of doing according to technical solution of the present invention all drops within protection scope of the present invention.

Claims (2)

1. three-phase/two-phase coordinate transformation method that is used on the frequency converter, it is characterized in that: described transform method can be with U with following step _a, U _b, U _cVoltage signal is converted to V under the three phase static coordinate system _D+And V _Q+Voltage signal under the two-phase rest frame:

Step 1: with U _aAnd U _bTwo phase voltage signals and U _bAnd U _cTwo phase voltage signals carry out the difference scale operation respectively in difference ratio arithmetic unit;

Step 2:, in the in-phase proportion arithmetic unit, carry out the in-phase proportion computing respectively, in homophase summation scale operation device, carry out homophase summation scale operation, the described U that finishes with the difference scale operation voltage signal that step 1 is finished _aU _bThe difference ratio arithmetic unit of two phase signals connects homophase summation scale operation device, finishes U _bU _cThe difference ratio arithmetic unit of two phase signals connects in-phase proportion arithmetic unit and homophase summation scale operation device simultaneously;

Step 3: voltage signal VD+ and VQ+ under the voltage signal output two-phase rest frame of completing steps two operation results.

2. three-phase according to claim 1/two-phase coordinate transformation method is characterized in that: at U _aU _bTwo phase voltage signals and U _bU _cConnect respectively between two phase voltage signals by a forward diode and the input protection circuit that backward diode is formed.

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