JPS6380766A - Method for controlling reversible static power converter - Google Patents

Abstract

PURPOSE:To shorten the selectively processing time of a converter group by deciding a method of selecting the converter group to be controlled from angle (phase) information for forming a current command value. CONSTITUTION:In a controlling method for a reversible static power converter such as a cycloconverter, a microcomputer calculates the winding current command values of phases by a current command value calculator 21. A current regulator 22 regulates the current by the current command value and the actual current value to control the phase of a thyristor. Further, a thyristor group selector 23 selects positive, negative thyristor groups in response to the polarity of each current command value. In this case, the angle A of the current command value is obtained by addition processors 21a, 21b from angle information and a constant B, the selector 23 selects the converter group to be controlled from the value, and judges whether it is converted or not. Thus, the selecting time of the converter group is shortened to accelerate the repetition period of the process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a reversible conversion device such as a cycloconverter.

[Conventional technology]

Figure 4 is a schematic configuration diagram of a direct frequency converter (hereinafter referred to as a cycloconverter) that supplies variable voltage, variable frequency AC power to a load, and Figure 5 is a waveform diagram showing waveform examples of each part of Figure 4. be.

C1 and C2 in Fig. 4 are controlled rectifier circuits consisting of thyristor bridges, where thyristor bridge C1 supplies a positive polarity current to the load, and thyristor bridge C2 supplies a negative polarity current, but the selection of these thyristor bridges This is performed by activating a thyristor selection signal as shown in FIG. 5(b) in accordance with the polarity of the current command value as shown in FIG. 5(a). Note that PC is a control device that controls the phase of the thyristor groups A and 5 by comparing the current value with the actual current value i.

Recently, with the development of computer technology, control devices have been digitized, and some systems have appeared in which cycloconverters are controlled by a plurality of microcomputers, for example. FIG. 6 is a block diagram showing a control device previously proposed by the applicant (Japanese Patent Application No. 51-159841; hereinafter also simply referred to as the proposed device).

In FIG. 6, the microcomputer 1 uses a speed adjustment section 12, a speed adjustment section 11, magnetic flux vector calculation sections 14, 15, 16, and a current command to adjust the vector to a thickness Il.
It has a vector conversion section that converts into a polar coordinate format represented by `` and an angle θ11 from the magnetic flux vector position, and performs various processes.Component II +01 of the current command value vector calculated by the microcomputer Δ11
1 is sent to microcomputers 2A, 2B, 2C. Microcomputer 2A, 2B.

2C is the winding current command value ia for each phase in the current command value calculation unit 21 based on the data and information on the angle ψ formed between the stator a-phase winding axis and the magnetic flux vector calculated by the magnetic flux position calculation unit 3.
, Ib, lc are calculated. Based on these current command values and actual current values ia, ib, and ic, the current adjustment section 22 performs current adjustment and performs phase control of the thyristor. moreover,
1 each in the thyristor group selection section 23! 9. Positive side depending on the polarity of the command value.

The negative side thyristor group is selected.

An example of the configuration of the magnetic flux position calculator 3 shown in FIG. 6 is shown in FIG. This is a digital-to-analog (D/A) converter 30.
Integrator 31, adder 32 and analog/digital (
The position ψ of the magnetic flux from the stator axis is determined from the A/D converter 33 using the following equation.

ψ=fω, tdt+θ ・・・・・・ (
1) An example of the current command value calculating section 21 in FIG. 6 is shown in FIG. MS8. This includes the addition section 21a #21b and the cosine function section 21.
C and a multiplication section 21d, and performs arithmetic processing according to the following equation.

(2) The microcomputers 2A, 2B, and 2C perform calculations of current command values, current adjustment, selection of positive and negative side converters, etc., but all of these are performed in synchronization with the generation of thyristor firing pulses. It will be done. For example, if the power supply frequency is 5011z, the calculation process will be repeated at an average interval of 3.3m5ec.

9 shows a control flowchart of the positive/negative converter group switching determination process in the control block diagram of FIG. 6.

First, the components of the current command value expressed in polar coordinates (the magnitude of the polar torque Il and the phase angle θi1 from the magnetic flux axis) are read out (see processes 1 and 2 in FIG. 9). Then, the angle ψ formed by the reference axis and the magnetic flux vector is read out (see Process ①). Calculate the angle using each input information (see same process ■),
Perform cosine function processing (see process ①) to obtain the instantaneous value l of the AC current command value (see surface processing ①). In addition, processing■
The constant B in is a constant to express the phase difference between the three phases. For example, if the value in the a phase is 0, the value in the b phase is (-danπ)
, the C phase becomes (-TI). Next, select the converter group whose phase should be controlled according to the polarity of the obtained AC current command value 1 (see the same process), compare it with the converter group currently under control, and if the converter group is the same, select the converter group whose phase is to be controlled. It is determined that there is no switching, and if the two are different, it is determined that there is switching (see the same process (■)).

The converter switching judgment process as described above is performed in synchronization with the thyristor firing pulse, for example, at 50Hz1! If done at the source, it would be done every 3.3 ms on average.

However, as the output frequency of the cycloconverter increases, if the selection of the positive and negative converter groups is determined in synchronization with the generation of the thyristor firing pulse, there will be a time delay in converter switching (for example, with a 50Hz power supply, it will take an average of 3.3ms).
(delay), the converter may not be switched at a certain point Δ, and the current command value and the actual current value may not match. For example, if the output frequency of the cycloconverter is set to 20
In Hz, a time delay of 3.3 ms corresponds to a phase shift of approximately 24°. Therefore, it is necessary to calculate the current command value at a fast sampling period and quickly detect the polarity reversal.

[Problem that the invention seeks to solve]

However, as is clear from the above explanation, current command value calculation includes multiplication processing and cosine function processing, and it is not possible to increase the repetition rate of current command value calculation due to the processing time required for these. As a result, in a region where the output frequency of the cycloconverter is high, the switching point of the converter group is delayed, resulting in a problem that the control performance of the control device deteriorates.

Therefore, an object of the present invention is to enable prompt detection of the switching point of each of the positive-side and negative-side converter groups constituting a cycloconverter, and to prevent deterioration of control performance.

[Means for solving problems]

A converter to be controlled is selected depending on the angle or phase of the sinusoidal current command value vector.

[Effect]

This invention focuses on the fact that the positive/negative character of the current command value for the stator of each phase is determined by the angle or phase formed between the stator winding axis of each phase and the current command value vector. This is an attempt to directly detect the polarity of the stator current command value.

[Embodiments of the invention]

FIG. 1 is a schematic diagram for explaining the invention in detail.

In the figure, the configuration and processing functions of each part are the same as those of the proposed method device (Figure 6), but the difference is that the angle information θ11. ψ
Addition processing 21a from and constant B.

21b, the angle value of the current command value is obtained, and from that value, the converter group to be controlled is directly selected by the thyristor group selection section 23, and it is determined whether or not switching is to be performed.

FIG. 2 is an example of a control flowchart according to the present invention, and FIG.
The same process numbers as the flowchart of the conventional method shown in the figure (■～■
) indicate the same processing content. Therefore, only the process (1) is different, which is to select the positive/negative converter group to be controlled based on the calculated angle size. FIG. 3 shows an example of the selection method.

In this example, as is clear from the figures (a), (C), and (d), in the range of 0°eL4' angle A to 90°, the positive converter group, 90°eL - < angle A (270 °”OWa
It can be seen that the negative 11i1: I y parter group, 270° Z angle A (in the range of 360', the positive side converter group, all are selected).

In this way, by selecting the converter group to be controlled based on the angle or phase information that forms the AC current command value, the cosine function processing and multiplication processing that were conventionally required for converter switching determination are no longer necessary. The processing time for switching judgment is shortened by that much, and switching judgment processing can be performed quickly and repeatedly. In addition, the current command value l
The calculation is performed using the angle A calculated by fast iterative processing, and the cosine function processing 1 is performed in synchronization with the generation of the ignition pulse as before.
It is obtained by performing multiplication processing.

〔Effect of the invention〕

According to the present invention, the selection method of the converter group to be controlled is determined from the angle (phase) information forming the current command value, so that the processing time for selecting the converter group is shortened and the processing speed is improved. It becomes possible to shorten the repetition period, and as a result, the detection delay time at the switching point of the converter group becomes short, which provides the advantage that deterioration of control performance can be prevented.

[Brief explanation of the drawing]

Figure 1 shows the implementation of this invention. A schematic diagram for explaining IJ, Figure 2 is a flowchart for explaining all its processing operations, Figure 3 is an operation waveform diagram showing an example of the positive side and negative side converter selection method, and Figure 4 is a general diagram. A schematic configuration diagram showing the frequency conversion device, FIG. 5 is a waveform diagram for explaining its operation, FIG. 6 is a configuration diagram showing the proposed method device, and FIG. 7 is a configuration diagram showing a specific example of the magnetic flux position calculation circuit. , FIG. 8 is a block diagram showing a specific example of the 'flL flow command value calculation section, and FIG. 9 is a 70-chart for explaining the conventional converter switching operation. Description of symbols 1.2A, 2B, 2C...Microcomputer, 3...Magnetic flux position calculator, 4...Cyclo converter, 5a to 5c, CT... Current detector d, 6... Electric i, 7... Rotor position detector, 8... Speed detector, 11...
・Magnetic flux adjustment part, 12... Speed adjustment nose part, 21a
, 21b... Addition section, 21c... Curved/cosine function calculation section, 21d... Multiplication section, 22... Quadruple flow adjustment section, 23... Thyristor group selection section, 3o...
・・D/A converter, 31・Song/integrator, 32・Song/adder, 33・・・・A/Di conversion i, CI, C2・
...Converter, PC...Control device. Agent Patent Attorney Akio Namiki Agent Patent Attorney Kiyoshi Matsuzaki

Claims (1)

[Claims] Operating the positive side converter and the negative side converter by switching each other,
A method for controlling a reversible converter, the method comprising: selecting a converter to be controlled according to the angle or phase of a sine wave current command value vector in the reversible converter supplying alternating current power of variable voltage and variable frequency to a load. .