CN101873100A - Simplified phase-voltage reconstruction method of three-level converter - Google Patents

Abstract

The invention provides a simplified phase-voltage reconstruction method of a three-level converter which is applicable to the converter using a three-level topological structure. The converter can supply power for a squirrel-cage motor speed governing system, a winding motor double-fed speed governing system and a synchronous motor speed governing system. The operating method of the three-level converter comprises the following steps: dividing a vector space output by the traditional three-level converter into six small hexagons, and then carrying out corresponding output phase-voltage reconstruction algorithms in the small hexagons; and finally achieving the purpose of three-level calculation by coordinate translation and compensation amount calculation. The algorithm is relatively simple, the obtained results can fully replace the results obtained by using an output sensor, and the results are more accurate than the results obtained by directly using a SVPWM command. The method simplifies system composition and improves reliability and stability of the system.

Description

Simplified phase-voltage reconstruction method of three-level converter

Technical field

The present invention relates to simplified phase-voltage reconstruction method of three-level converter, be applicable to squirrel-cage motor, coiling electric motor and the synchronous motor of three-level converter power supply.

Background technology

In three level high-performance motor vector control systems, output phase voltage whether accurate performance to system excellent very big influence.Traditional method has two kinds at present, and a kind of is to adopt output voltage sensor to be sampled in the control system by AD.Second kind is directly to adopt the instruction of SVPWM to export phase voltage as reality.

For first method, must increase corresponding AD number of active lanes when needing to increase transducer, and the voltage of three-level converter output is staircase waveform, with common instantaneous sampling A/D converter adopt value be not the mean value of actual waveform in a switch periods, can not truly reflect the size of output voltage in this switch periods.For second method, the burst pulse problem is its inaccurate source, because the instruction of not all output and SVPWM is identical to establishing a capital, particularly in motor low speed and high regime, the burst pulse problem is more serious.

Simultaneously since three level output levels than two level topological structures mostly, and output voltage vector three times of two level especially, if directly by the output voltage order, add respectively that master vector, zero vector and inferior vector calculate action time the unusual difficulty of words.But ripe relatively computing formula is arranged for two level, we adopt traditional two level topological structure frequency converter output voltages to calculate, when reducing amount of calculation, reduced system hardware structure, can obtain again simultaneously and compare second method precise output voltage more.

Therefore, in the frequency converter of three level topological structures, adopt the three level phase-voltage reconstruction algorithms of simplifying, will improve the technical guarantee of control system reliability and accuracy.

Summary of the invention

Technical problem: the purpose of this invention is to provide at the method for three level topological structures output phase-voltage reconstruction and the converter plant that adopts this method.Simplify the hardware configuration of three level topological structure frequency converters on the one hand, improved the reliability and the accuracy of converter plant on the other hand.

Technical scheme: a kind of simplified phase-voltage reconstruction method of three-level converter specific implementation process of the present invention is:

The first step: at first to the DC bus-bar voltage V of frequency converter _DcSample, and the record result;

Second step: according to the three dimensional vector diagram of three-level converter, the three dimensional vector diagram of three-level converter, formed, calculate T action time of A, B, C phase thus by the little hexagon that six two traditional level space vectors constitute _a, T _b, T _c, the while is at the subcarrier time T of system _sCarry out the phase voltage V of A, B, C phase under the two level topological structures _An, V _Bn, V _CnThe calculating of reconstruct,

$V_{\mathrm{an}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_a-\frac{1}{3}{T}_b-\frac{1}{3}{T}_c)/T_s$

$V_{\mathrm{bn}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_b-\frac{1}{3}{T}_a-\frac{1}{3}{T}_c)/T_s$

$V_{\mathrm{cn}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_c-\frac{1}{3}{T}_b-\frac{1}{3}{T}_a)/T_s,$

The 3rd step: for the reconstruct of output phase voltage down of three level topological structures, utilize coordinate translation, it is to carry out in the little hexagon at center that the voltage vector that needs reconstruct is positioned at respectively with V1, V2, V3, V4, V5, V6, and each little hexagon just can be regarded the space voltage vector figure of one two level topological structure as; And then each little hexagonal center component on A, B, C axle measured by way of compensation, be added on the result who produces with phase-voltage reconstruction under the two level topological structures,

$V_{\mathrm{an}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_a-\frac{1}{3}{T}_b-\frac{1}{3}{T}_c)/T_s+V_{a\_\mathrm{compensation}}$

$V_{\mathrm{bn}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_b-\frac{1}{3}{T}_a-\frac{1}{3}{T}_c)/T_s+V_{b\_\mathrm{compensation}}$

$V_{\mathrm{cn}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_c-\frac{1}{3}{T}_b-\frac{1}{3}{T}_a)/T_s+V_{c\_\mathrm{compensation}},$

According to the different little hexagon that reference voltage vector is positioned, the compensation rate that obtains A, B under each situation, C phase is as follows:

Little hexagon number	A phase compensation rate V a_compensation	B phase compensation rate V b_compensation	C phase compensation rate V c_compensation
				??1	??+V dc/3	??-V dc/6	??-V dc/6
??2	??+V dc/6	??+V dc/6	??-V dc/3
				??3	??-V dc/6	??+V dc/3	??-V dc/6
??4	??-V dc/3	??+V dc/6	??+V dc/6
				??5	??-V dc/6	??-V dc/6	??+V dc/3
??6	??+V dc/6	??-V dc/3	??+V dc/6

Beneficial effect: the converter plant of said method and this method of employing, utilize three level and the equivalent relation of two level on space voltage vector, directly action time, information obtained each phase output voltage by corresponding calculating mutually with each by dc bus information, concerning electric machine control system, omitted the correspondent voltage transducer, simplified the hardware configuration of system, the reliability height of the phase voltage that obtains of this method simultaneously, carry out the phase voltage estimation approach with direct employing reference voltage vector and compare and have higher precision, improved the velocity control accuracy of system at high regime and low speed segment.

Description of drawings

Fig. 1 is three level space voltage vector figure,

Fig. 2 is that three level space voltage vectors are decomposed into 6 little hexagon figure,

Fig. 3 is bucking voltage figure in the simplified phase-voltage reconstruction algorithm under the three level topological structures,

Fig. 4 is the converter plant figure that adopts the simplified phase-voltage reconstruction algorithm under the three level topological structures,

Among the figure: the panel 5 of frequency converter 3, controlled motor 4, velocity setting and the enabling signal of three-phase alternating current input power supply 1, mains switch 2, three level topological structures, system controller 6, voltage sensor 7, triggering optical fiber 8, motor A phase current transducer 9, motor C phase current transducer 10, encoder 11.

Embodiment

The three dimensional vector diagram of three-level converter shown in Figure 1 can be thought to be made up of the little hexagon that six two traditional level space vectors constitute, each the little hexagon that constitutes the three dimensional vector diagram of three-level converter is the center with little hexagonal summit, inside all, as shown in Figure 2.

If current carrier cycle is T _s, T _a, T _b, T _c, be respectively action time of A, B, C phase, then the output reconstruction formula of phase voltage is under the two level topological structures:

$V_{\mathrm{an}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_a-\frac{1}{3}{T}_b-\frac{1}{3}{T}_c)/T_s---\left(1\right)$

$V_{\mathrm{bn}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_b-\frac{1}{3}{T}_a-\frac{1}{3}{T}_c)/T_s---\left(2\right)$

$V_{\mathrm{cn}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_c-\frac{1}{3}{T}_b-\frac{1}{3}{T}_a)/T_s---\left(3\right)$

For the reconstruct of output phase voltage down of three level topological structures, can utilize coordinate translation, it is to carry out in the little hexagon at center that the voltage vector that needs reconstruct is positioned at respectively with V1, V2, V3, V4, V5, V6, as shown in Figure 2, each little hexagon just can be regarded the space voltage vector figure of one two level topological structure as.And then each little hexagonal center component on A, B, C axle measured by way of compensation, be added on the result who produces with phase-voltage reconstruction under the two level topological structures, as shown in Figure 3.

$V_{\mathrm{an}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_a-\frac{1}{3}{T}_b-\frac{1}{3}{T}_c)/T_s+V_{a\_\mathrm{compensation}}---\left(4\right)$

$V_{\mathrm{bn}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_b-\frac{1}{3}{T}_a-\frac{1}{3}{T}_c)/T_s+V_{b\_\mathrm{compensation}}---\left(5\right)$

$V_{\mathrm{cn}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_c-\frac{1}{3}{T}_b-\frac{1}{3}{T}_a)/T_s+V_{c\_\mathrm{compensation}}---\left(6\right)$

Be positioned different little hexagon number among Fig. 2 according to reference voltage vector, the compensation rate that can obtain A under all situations, B, C phase is as shown in table 2:

Table 2: the phase voltage compensation rate under the different little hexagons number

Little hexagon number	A phase compensation rate V a_compensation	B phase compensation rate V b_compensation	C phase compensation rate V c_compensation
				??1	??+V dc/3	??-V dc/6	??-V dc/6
??2	??+V dc/6	??+V dc/6	??-V dc/3
				??3	??-V dc/6	??+V dc/3	??-V dc/6
??4	??-V dc/3	??+V dc/6	??+V dc/6

Little hexagon number	A phase compensation rate V a_compensation	B phase compensation rate V b_compensation	C phase compensation rate V c_compensation
				??5	??-V dc/6	??-V dc/6	??+V dc/3
??6	??+V dc/6	??-V dc/3	??+V dc/6

The three level phase-voltage reconstruction principles that the present invention simplifies:

The main controller 6, three level power converter 3 of utilizing is controlled motor 4 power supplies, sees Fig. 4.Wherein will measure the DC bus-bar voltage signal feedback of coming and give controller 6 by voltage sensor 7, velocity setting and enabling signal are given to controller 6 by guidance panel 5, controller 6 provides the correspondent voltage reference vector by velocity setting sampling with to the burst process of encoder 11, judge the residing little hexagon of this vector number, and then trigger by three level triggers modules and optical fiber 8.Thereby constitute the closed loop speed control system of controlled motor, can control accurately the speed of controlled motor

The phase-voltage reconstruction of three level calculate then by DC bus-bar voltage with from three level triggers modules, obtain residing little hexagon of current reference voltage vector number and A mutually, other action time of branch of B phase, C phase, based on formula (4), (5), (6), the compensation rate the judged compensation rate according to table 1 is compensated.

Simplified phase-voltage reconstruction method of three-level converter of the present invention mainly is made up of controlled motor and control system.Frequency converter 3, frequency converter 3 that controlled motor 4 windings are received three level topological structures are connected to three-phase alternating current input power supply 1 by mains switch 2.The A of motor windings, the C over-current sensor 9 and 10 that communicates is connected to system controller 6, DC bus-bar voltage is connected to system controller 6 by voltage sensor 7, velocity setting signal and enabling signal then are connected to system controller 6 by guidance panel 5, and system controller 6 goes the frequency converter 3 of three level topological structures is carried out the conducting of IGBT or the control that ends by optical fiber 8.The feedback speed signal of system then calculates by encoder 11, and the three level phase-voltage reconstruction algorithms that phase voltage is then passed through the simplification of this aspect obtain.

Claims (1)

1. simplified phase-voltage reconstruction method of three-level converter is characterized in that this reconstructing method specific implementation process is:

The first step: at first to the DC bus-bar voltage V of frequency converter _DcSample, and the record result;

Second step: according to the three dimensional vector diagram of three-level converter, the three dimensional vector diagram of three-level converter, formed, calculate T action time of A, B, C phase thus by the little hexagon that six two traditional level space vectors constitute _a, T _b, T _c, the while is at the subcarrier time T of system _sCarry out the phase voltage V of A, B, C phase under the two level topological structures _An, V _Bn, V _CnThe calculating of reconstruct,

$V_{\mathrm{an}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_a-\frac{1}{3}{T}_b-\frac{1}{3}{T}_c)/T_s$

$V_{\mathrm{bn}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_b-\frac{1}{3}{T}_a-\frac{1}{3}{T}_c)/T_s$

$V_{\mathrm{cn}}=V_{\mathrm{dc}}(\frac{2}{3}{T}_c-\frac{1}{3}{T}_b-\frac{1}{3}{T}_a)/T_s,$

The 3rd step: for the reconstruct of output phase voltage down of three level topological structures, utilize coordinate translation, it is to carry out in the little hexagon at center that the voltage vector that needs reconstruct is positioned at respectively with V1, V2, V3, V4, V5, V6, and each little hexagon just can be regarded the space voltage vector figure of one two level topological structure as; And then each little hexagonal center component on A, B, C axle measured by way of compensation, be added on the result who produces with phase-voltage reconstruction under the two level topological structures,

$V_{\mathrm{an}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_a-\frac{1}{3}{T}_b-\frac{1}{3}{T}_c)/T_s+V_{a\_\mathrm{compensation}}$

$V_{\mathrm{bn}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_b-\frac{1}{3}{T}_a-\frac{1}{3}{T}_c)/T_s+V_{b\_\mathrm{compensation}}$

$V_{\mathrm{cn}}^{\′}=V_{\mathrm{dc}}(\frac{2}{3}{T}_c-\frac{1}{3}{T}_b-\frac{1}{3}{T}_a)/T_s+V_{c\_\mathrm{compensation}},$

According to the different little hexagon that reference voltage vector is positioned, the compensation rate that obtains A, B under each situation, C phase is as follows:

Little hexagon number A phase compensation rate V _{a_compensation} B phase compensation rate V _{b_compensation} C phase compensation rate V _{c_compensation} ??1 ??+V _dc/3 ??-V _dc/6 ??-V _dc/6 ??2 ??+V _dc/6 ??+V _dc/6 ??-V _dc/3 ??3 ??-V _dc/6 ??+V _dc/3 ??-V _dc/6 ??4 ??-V _dc/3 ??+V _dc/6 ??+V _dc/6 ??5 ??-V _dc/6 ??-V _dc/6 ??+V _dc/3 ??6 ??+V _dc/6 ??-V _dc/3 ??+V _dc/6 。

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