SU1128353A1 - Method of adjusting device for supplying periodic current with inverted pulse to load - Google Patents

Abstract

METHOD FOR CONTROLLING A LOADING POWER SUPPLY DEVICE WITH A REVERSE CURRENT WITH A REVERSE PULSE, including a thyristor group connected to a three-phase supply voltage source, a forward current pulse and a thyristor group, a cross section pulse, a cross section, and a cross section of the drawing, and the drawing will be applied. what, for the purpose of povisheni. reliability and frequency of a periodic current, in each period of power supply, the first in the thyristor group, forming a current pulse in the forward direction, include the thyristor of the phase of the supply voltage, lagging behind in the sequence of phases in the preceding power period, and in the thyristor group, In each period of the power supply, the thyristor of the phase of the forward current pulse voltage lagging behind in this period after the polarity of the voltage of this phase is reversed is turned on.

Description

one

The invention relates to the field of electrical engineering and can be used in devices for supplying a load, for example, an electrolytic bath, with a periodic current with a reverse pulse.

There are known devices for feeding electrolyte baths with a periodic current with a reverse pulse, which can be classified according to two features: devices with an asymmetrical valve connection on the secondary side of the power transformer lj - 3 and devices with a symmetric valve connection on the secondary side of the power transformer 4 - 6j.

The disadvantages of the first group of devices are the uneven loading of the supply phases of the transformer, the increased installed power of these transformers and the deterioration of the quality of the power supply networks.

The second group of devices ensures uniform loading of the supply phases of the transformer and the electrical network, low impact on the quality of the energy of the supply networks, the installed power of the transformers

corresponds to the nominal.

G,.

Such devices contain a power transformer, to the secondary side of which two connected thyristor groups are connected oppositely parallel: one generates a current pulse of the forward direction and another of the current pulse of the reverse direction, and the current poles of these thyristor groups are connected to the electrolytic bath.

These devices have a number of drawbacks, which are caused by the imperfection of their control methods, leading to a decrease in the reliability of the devices, to a low frequency of a periodic current, as a result of which the efficiency of the galvanic bath is reduced.

The closest to the invention in its technical nature is a method for controlling a device to supply a load with a periodic current with a reverse pulse, including a group of tristors connected to a three-phase source of supply voltage, forming a current pulse of direct voltage, and a group of trisris 283532

tori, forming a pulse of current of reverse voltage, which consists in alternately turning on the thyristors of the above groups 6 | . 5 A disadvantage of the known control method is that the maximum frequency of a periodic current can be as low as 20 Hz, and the reliability of the device due to the 10 limited sensitivity of the current sensor near current zero is low.

The aim of the invention is to increase the reliability and frequency of the periodic current.

This goal is achieved by the fact that, according to the method of controlling a device for supplying a load with a periodic current with an o6paVHbiM pulse including the connected

20 to a three-phase power supply source a thyristor group forming a forward current pulse and a thyristor group forming a reverse current pulse

5 directions, consisting in alternately switching on the thyristors of the above groups, B each feeding period first in the thyristor group forming the forward current pulse, include the thyristor of the supply voltage phase lagging behind in the phase rotation sequence in the previous feeding period, and in the thyristor group Forming a current pulse of the reverse direction, in each period of the power supply, the thyristor of the phase of the forward current voltage lagging behind in this period is switched on after changing the polarity of the voltage of this phase to about atnuyu.

Fig. 4.1 shows the functional diagram of the device for supplying the electrolytic bath with a periodic current with a reverse pulse as power, Fig. 2 shows a plot of the currents of the electrolytic bath explaining how to control the device.

0. The device contains a control system 1, a group of 2 direct current, consisting of thyristors 3-5, the anodes of which are connected to the terminals of the secondary winding of the transformer

5 6, current sensor 7, electrolytic bath 8 with anode 9 and cathode 10, reverse current group 11 consisting of thyristor 12-14, the cathodes of which are connected to the terminals of the same secondary winding transformer 6. Thyristor cathodes 3-5 and thyristor anodes 12-14 are interconnected and connected to the anode 9 of the electrolyte bath 8, the cathode 10 of which is connected to the common output of the transformer 6 connected in a star.

The method is carried out as follows.

At time t, the device power-on time from system 1; the control serves a control pulse to the control electrode of one of the thyristors of group 2, which forms a current pulse of the forward direction inp, namely, the one on which the anode currently has an instantaneous value Positive polarity is greatest, for example, for a thyristor of 3 phases and a transformer 6. Thus, this thyristor is included.

A direct current flows through the electrolyte bath 8 in the direction from the anode 9 to the cathode 10. Further, in the order of phase alternation, the thyristors 4 and 5 of phases B and C are included, respectively, at time t tg times. The times t, t ll ll tj are determined by the control angle of the control pulses, i.e. given current value inp.

After switching on the thyristor 5 phase Q, the control pulses of group 2 of the thyristors are blocked. After changing the polarity of the phase phase to reverse from the control system 1, a control pulse is applied at time tts to the thyristor 14 of the phase of group 11, which forms a current pulse of the reverse direction iogp. Thereby include this thyristor.

Through the electrolyte bath 8 in the direction from the cathode 10 to the anode 9 current begins to flow. reverse direction. The time t is determined by the control angle of the control pulse, i.e. set current iobp. After switching on the thyristor 14 of phase Z, the control pulses of group 11 are blocked.

Due to the fact that the thyristors 5 and 15 are included in an anti-parallel, in a single phase, the possibility of a short circuit is completely excluded.

283534

Thus, in the feeding period of a T. electrolyte bath, the thyristors are included in the following order of phase alternation: a-b-c z. :

5 In the next period T, the electrolytic bath power supply during the formation of a current pulse in the forward direction includes the thyristor 5 of phase c, i.e. thyristor phase supply

to voltage, lagging in the order of alternation of phases in the previous period of feeding the electrolyte bath. This completely eliminates the possibility of short circuits.

15 Next, in order of phase rotation.

include thyristors 3 and 4 phases a and b, respectively.

To form the next current pulse of the reverse direction

20 after the change of the voltage of phase b to, the reverse involves the thyristor 13 of phase ij, i.e. in the power period T of the electrolyte bath, the thyristors include in the order of alternation

5 phases: c-oi-b).

Similarly, in the TJ period of the electrolyte bath, the thyristors include c. order of phase rotation: b –c –a – X.

0 After the period T is complete, the process of controlling the power supply device is repeated cyclically. Period

TO, - T, + Tg,

cycle, power T ,.

The order of phase rotation, which includes the power device thyristors, is as follows:

: а-в-с-2-с-аб-1 | -8-с-о-ч

Stabilization of direct and

the reverse directions are carried out by the signals of the current sensor 7, while in connection with the elimination of the possibility of the occurrence of deaf short circuits, the requirements to the sensitivity of the current sensor near zero current are reduced.

Eliminating the possibility of KopoTKijx closures during the formation of a reverse current pulse after the end of the forward current pulse and vice versa, will ensure high reliability of the power device when using the proposed method

his management.

According to the proposed method of controlling the electrolytic bath power supply device in each particular period (TD, T, T (.)), The bath power supply in the reverse current pulse has only one time interval when the bath is de-energized. This will lead to an increase in the performance of the electrolyte bath at high energy characteristics. Litani bath devices with periodical current with reverse pulse

som

Claims (1)

METHOD FOR CONTROLLING A DEVICE FOR POWER LOADING WITH A PERIODIC CURRENT WITH A REVERSE PULSE, including a group of thyristors connected to a three-phase power supply source, forming a forward direction current pulse and a thyristor group forming a reverse direction current pulse, which consists of turning on the thyristors in turn, in order to increase the reliability and frequency of the intermittent current, in each power period it is the first in the group of thyristors that forms a direct current pulse lines, include the thyristor of the phase of the supply voltage, which lagged behind in the sequence of phases in the previous supply period, and in the group of thyristors that forms the reverse current pulse, in each supply period, include the thyristor of the forward phase current phase voltage lag in this period after changing the polarity of this voltage phase to the opposite. KWT’W