JPS5815468A - Control system for cycloconverter - Google Patents

Abstract

PURPOSE:To control the firing phase of a self-excited converter to the desired phase by individually providing a pulse generator in response to the polarity of an output current and adjusting the output of a current regulator with a preliminary regulator at the time of switching the output current polarity. CONSTITUTION:When the switching of the polarity of an instructed value Isoll is detected to output a shift signal C, the fact that the actual value Iist is zero is confirmed to stop a gate pulse to one converter, the output of a preliminary regulator 15 is applid via the output SE of a setter 14 through a switch 16 to a current regulator 1 according to the shift signal C' or C''. Since no input exists in the regulator 1, the regulated output responsive to the output of the regulator 15 is outputted at AC, is applied directly or through a polarity inverter 4 to a pulse generator 5 or 17, thereby controlling the phase so that the control angle -alpha of self-excited converters 10, 11 becomes smaller than 60 deg.el.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control method for a reactive current compensation type cycloconverter with no circulating current, and particularly to a control method for a self-excited converter at the time of polarity switching of its output current (load current).

The separately excited converters and self-excited converters that make up such a cycloconverter are divided into those that operate on each positive half-wave of the output current (load current) and those that operate on each negative half-wave of the output current (load current). These switchings are performed, for example, by determining the target value polarity of the output current and confirming that the actual current value is zero. That is, checking that there is no current in the converter belonging to one polarity, blocking the gate pulse to the converter, and then supplying the gate pulse to the converter belonging to the other polarity after a predetermined current stop period. The non-circulating current control, well known in the stationary Leonard art, is performed to initiate . By the way, the output voltage phase of a converter, especially a self-excited converter, may become negative polarity immediately after the current stop period, and until this becomes a positive voltage phase, conversion will not occur even if a gate pulse is applied. The device may generate an output voltage, so this time may be wasted.

This point will be explained below with reference to FIGS.

FIG. 1 is a block diagram showing the phase control method of such a cycloconverter, and FIGS. 2 and 3 are waveform diagrams showing the output of the phase control signal switch and the output voltage waveform of the cycloconverter at the time of switching. In the figure, 1 current regulator\2 is a phase control signal switch 1.3, 5 is a pulse generator, 4 is a polarity inverter, 6,
7 is a pulse on/off switch, 8゜9 is a separate excitation converter, 1
0 and 1.1 are self-exciting converters, 12 is a current detector, and 13 is a load. The converters 8 to 11 constitute a cycloconverter. The output of the 1° current regulator 1 is connected to the phase control signal switch 2. pulse generator 3 or polarity inverter 4
pulse generator 5 and on/off switch 6゜7 via
to a converter 8.9 or 10,11. The current regulator 1 outputs a regulating output so that the current (current current value Ij, st) flowing through the load 13 of the cycloconverter detected by the output current detector 2 becomes the target value (l5oll). 5 receives the output of the current regulator 1 via the phase control signal switch 2, and determines the ignition phase by comparing the output with a predetermined signal synchronized with the power source). A gate pulse is supplied to each gate of the constituent thyristors. Note that the gate pulse of the self-excited converter 10 r 1.1 is separately excited
.

The polarity is opposite to that of 9 (inverted by the polarity inverter 4), and its synchronization signal is also phase shifted by 180°d (electrical angle).

Pulse signals A, B and C are given at the timing shown in FIG. That is, pulse signal A is used when controlling the thyristor on the body side, pulse signal B is used when controlling the thyristor on the opposite side, and pulse signal C is used to hold the current regulator 1 at zero and its output to zero. (see N in Figure 2).

The output voltage of the cycloconverter at the time of polarity change of the output current is, for example, as shown by voltage ■ in Figure 3. Immediately after the output current is switched (in the figure, the time of switching from the opposite side to the body side), at time to, The output of the separately excited converter (solid line) is positive, but the output of the self-excited converter (dotted line) is negative, and during this time it is possible to output even if a gate pulse is applied, which results in the switching wasted time mentioned above. This is known to occur particularly when the firing phase immediately after switching (to time point) is greater than 1 α-60°d.

The present invention has been made in view of the above, and an object of the present invention is to provide a control method for a cycloconverter that can shorten the above-mentioned switching dead time as much as possible and perform good operation control. According to the present invention, a current regulator for regulating the output current of a reactive power compensation type cycloconverter without circulating current is provided with a preparation regulator for controlling the regulation output thereof, and a self-excited converter The pulse generation circuit for each stage is individually controlled according to the polarity of the output current.At the time when the output current polarity is switched, the output of the current regulator Nj is controlled by the preparation regulator to adjust the firing phase of the self-excited converter. This is achieved by controlling the

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a configuration diagram showing an embodiment of this invention, and FIG.
FIG. 3 is a timing chart for explaining the operation of the figure.

In Figure 4, the symbols 1 to 13 are numbered 1.
It is similar to that shown in the figure and therefore differs from the conventional one in that it has added an initial phase setter 14, a readiness regulator 15, a switch 16, a pulse generator 17 and pulse shift signals c', C''. There is.

As shown in FIG. 5, the pulse shift signals C' and C'' are set according to the positive or negative polarity of the sine wave current command value (18011) on the condition that both the pulse signals A and B are off. Therefore, the switching of the polarity of the sine wave current command value (Loll) is detected and the pulse shift 1 signal C is output to confirm that the 1 current actual value (hst) is zero. When blocking the converter gate pulse 1 readiness regulator 15 ni, pulse shift signal C
Since the set value from the setter 14 (see waveform SE in FIG. 5) is given by ' or C'', the adjustment output of the preparation regulator 15 is given to the current regulator fIi 1 via the switch 16.

At this time, since there is no other input to the current regulator 1, it outputs a regulation output according to the output of the preparation regulator 15 (see waveforms A and C in Figure 5), which can be output directly or through the polarity inverter 4. By supplying the signal to the pulse generating circuit 5 or 17 via the pulse generating circuit 5 or 17, the phase of the self-excited converter 10.11 is controlled so that the control angle -α of the self-excited converter 10.11 becomes smaller than 60°el. In addition,
The setting value set by the setting device 14 is selected to be an appropriate value depending on the type of load (resistance load, inductance load, etc.) or the power factor. In addition, the quasi-semi-regulator 15 has a low output frequency of the cycloconverter, and the current regulator 1
When is a PI regulator, the capacitor is connected as a first-order delay element as shown by the dotted line in Figure 4, and the frequency is large.
When the current regulator 1 is a P regulator (when the capacitor of the current regulator is short-circuited as shown by the dotted line in Figure 4), it is adjusted with the current regulator as a P regulator 1i as shown by the solid line in the figure. This is desirable.

As described above, according to the present invention, the preparation regulator (P regulator or first-order delay Since the converter has an additional pulse generator for the self-excited converter, there is almost no wasted time immediately after switching the forward/reverse converter, and good operation can be achieved.

It should be noted that the present invention can be applied to a Leonard device in addition to the circulating current-free reactive power compensation type cycloconverter described above.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the phase control method of a conventional cycloconverter, Figure 2 is a waveform diagram showing the output waveform of the phase control signal switch during switching, and Figure 3 is a diagram of the output voltage waveform of the cycloconverter. FIG. 4 is a configuration diagram showing an embodiment of the present invention, and FIG. 5 is a timing waveform diagram for explaining the operation of FIG. 4. Description of symbols 1...Current regulator, 2...Phase control signal switch, 3, 5, 1.7...Pulse generator, 4... Polarity inverter, 6.7...Pulse on/off switch, 8,9°°゛...Separately excited converter,
10 F 11...Self-excited converter, 12...
...Current detector, 13...Load, 14...
...Initial phase setter, 15...Preparation adjuster, 1
6...Switch, A...Body side pulse-on signal, B...Reverse side pulse-on signal, C1C'
, to C...Pulse shift signal agent Patent attorney Akio Namiki Patent attorney Kiyoshi Matsuzaki

Claims (1)

[Claims] A reactive power compensation type cycloconverter that is formed by combining a predetermined number of self-excited converters that are controlled with a phase angle that leads with respect to the power supply voltage and separately excited converters that are controlled with a phase angle that lags with respect to the power supply voltage. a current regulator that adjusts the output current of the output current, and a pulse generation circuit that supplies firing pulses to predetermined self-excited and separately excited converters according to the desired polarity of the output current,
In a control method for a cycloconverter, the output current or voltage of the cycloconverter is controlled by controlling the phase angle of the ignition pulse using the adjustment output, and a preparation regulator is provided to control the output of the current regulator; The self-excitation conversion is achieved by separately providing a pulse generation circuit corresponding to the automatic converter according to the polarity of the output current, and adjusting the output of the current regulator with the preparation regulator when the output current polarity is switched. A control method for a cycloconverter 0 characterized in that the ignition phase of the device is set to a desired phase.