SU826524A1 - Transformer-thyristor voltage regulator - Google Patents

Description

one

The invention relates to a technique for stabilizing and regulating AC voltage.

Transistor-thyristor voltage regulators are known, in which the change in the output voltage is carried out by a multiple change in the half-period between the switching intervals of a large and a smaller transformation coefficient l,

G2 and W.

These devices have drawbacks in the form of a significant increase in voltage on the switching elements during operation, greater design power of reactive elements and, accordingly, reduced reliability of the controller ..:

The closest known to the proposed is the regulator, consisting of a power transformer of two rectifying bridges connected to the adjusting branches of the windings, two thyristors, back-shunted diodes connected to the output of rectifying bridges through separating inductances and LC circuits of the 3JJ thyristor cathodes and anodes

In connection with the occurrence of adjustment windings in the switching intervals of the short-spinning mode, and to limit the short-circuit currents in the DC mode of the rectifying bridges, dividing inductances are included. However, under this inclusion scheme, there is a significant deterioration in the energy indicators of the regulator.

This is associated with a large amount.

Bc iiria i

appropriate power

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energy, stored in separate inductances, which is then transferred to switching capacitors.

In addition, when the required inductance value is dramatically slowed

0 current switching in control windings in the process of switching, which deteriorates sharply; Controllers.

The purpose of the invention is to reduce the power of the switch, improve energy performance and increase the reliability of the controller.

This goal is achieved by the fact that the controller is equipped with two inverters, of which are connected to

one of the two groups of additional windings of the transformer and is connected in series with the corresponding of the indicated thyristors, and the separation inductances are made in the form of four located on one core according to the included windings, two of which are connected between the cathode group - and the gates of the indicated bridges, and the other two - between the anode ones in groups.

The drawing shows the power part of the transformer-thyristor regulator circuit.

The regulator consists of a power transformer 1, the adjusting taps of windings 2 and 3 of which are connected to rectifying bridges 4 and 5 of two windings b, 7 and 8.9 of four-section throttle 10, diodes 11, 12 of capacitance 13, 14, inductance 15,

16, thyristors 17, 18, which are shunted in the opposite direction by diodes 19, 20. Inverters 21, 22 are connected in series with each of the thyristors and are connected to separate windings 23, 24 of power transformer 1.

-Between anodes and thyristor cathodes

17.18 included capacitors 25, 26 and inductances 27, 28

Smooth regulation of the current and average voltage of the transformer in the proposed controller is achieved by multiple changes within a half-period of the ratio between the switching intervals of the larger and smaller transformation ratio. Within a half cycle, with a high degree of uniformity and synchronization with respect to the fundamental frequency, control pulses are applied to the thyristor 17, which switches to a lower transformation ratio. The mezvu intervals of two thyristor 17 control pulses form repetitive switching cycles of transformer adjustment taps, starting with switching on the thyristor 17. At the beginning of this cycle, opening the thyristor 18 at the beginning of this cycle is preceded by opening the thyristor 18 within the previous switching cycle. When the thyristor 17 is opened in the switching circuit including the capacitor 25, 26 and inductance 27j 28, the current increases due to the correlation of the voltages on the capacitors and the inductances of the switching circuit. Each of the thyristors is shunted in the opposite direction with diodes 19, 20 to ensure that the switching process is independent of the currents in the transformer windings.

During the thyristor switching interval, the transformer's adjustment taps are closed

simultaneously through both rectifying bridges 4 and 5.

To limit the rate of increase of the current in the short circuit circuit of the adjusting winding, the thyristors are connected to rectifying bridges through windings 6–9 of four-section throttle 10. Polarities The connections of the windings of this throttle are shown in the drawing.

Q During the short circuit interval, all sections of the chokes in the rectifier bridge circuit are turned on according to which minimizes the buildup of the additional current in the controllable current transformer during this interval.

At the same time, with this inclusion of the winding section 6-9, the transfer of current from the contour of one expelling bridge to the contour of the other is not associated with a significant change in the flux linkage of the throttle windings and that inductance, which limits the increase in ds. n | 1 does not actually delay the process of switching the current from the circuit of one rectifying bridge to the circuit of the other.

Due to this, the switching of the main load current between the transformer branches MMS branches

Q is not related to the relatively large total inductance of chokes 10, which is necessary to limit the loop current during the short circuit interval.

- At the same time, in the switching circuit of the main load current between the adjusting taps of the transformer, there is a relatively small component of the inductance of the choke 10, corresponding to the leakage inductance of the windings (b + 7 and (8 + 9) of this droselle.

Due to the fact that during the switching interval of the thyristors, the switching circuit for the other circuits is short-circuited, there is some accumulation of energy in the four-section choke, significantly reduced due to a significant limitation of the current increase due to the large inductance value for the DC circuits with a consistent magnetization of the core throttle from the currents of all four sections. However, without withdrawing this energy

Claims (3)

5, the core of the throttling core is rapidly followed by a sharp increase in the voltage across the commutating capacitors. To prevent these occurrences, an inverter converter is connected in series with each of the two thyristors 17, 18, connected to the additional windings of the power transformer. In this case, when polarization of the switching capacitors occurs, the corresponding charge of the capacitors 13, 14, KOTOfXje is then discharged through inverters 21, 22. Depending on the ratio of the capacitors 13, 14 and 25, 26, you can set the required level of the maximum voltage across the capacitors. 25, 26. The power that is inverted from the switching circuit depends primarily on the thyristor off time, control range and switching frequency. For a number of switches of about 10 within a half-period of 1 to 50 Hz and a short circuit interval of about 1000 µs. Switching inverter inverters in series with thyristors provides a significant increase in the efficiency of the control system by reducing the total losses in the switched transformer by about 2-3 times. Claims of the Invention Transformer-thyristor voltage regulator, consisting of a transformer of Sev, two rectifying bridges connected to the adjusting branches of its windings, two thyristors, which are shunted in the opposite direction with diodes connected to the output. rectifying bridges through dividing inductances, and LC chains between the cathodes and anodes of the thyristors, distinguished with that, in order to improve energy performance and improve reliability, the regulator is equipped with two invertorams, each of which is connected to one of two groups of additional windings of the transformer and connected in series with the corresponding of the indicated thyristors, once the separation inductances are performed in the form of four located on the same core according to the included mats, two of which are connected inen between the cathode groups of valves of the indicated bridges, and the other two between the anode groups : Sources of information taken into account in the examination 1. US Patent No. 3596172, cl. 323-45, 1971. 2. Authors certificate of the USSR 334562, cl. G 05 F 1/14, 1972. 3. USSR author's certificate № 3118137, cl. G 05 F 1/14, 1971.