SU886168A1 - Ac voltage-to-dc voltage converter - Google Patents

Description

I

The invention relates to a converter technique and can be used to power various DC consumers.

The classical schemes for converting three-phase alternating voltage to constant voltage are known, among which, in particular, are six-phase with zero. the output and six-phase rectification circuit with the connection of the secondary windings in a double zigzag D.

However, the six-phase circuit, with zero, has an unfavorable course of external characteristic, poor use of valves over current, and when connecting the primary windings into a star, the forced magnetization flow pulses with a threefold frequency.

These deficiencies are largely absent in the well-known transformation scheme with the connection of the secondary windings into a double zigzag 23.

However, this scheme has its main drawback, namely, the poor use of current valves due to the unfavorable ratio between the average l and maximum 1a, (3 values of the anode current and the duration of its flow j equal to only 60 electrical degrees. This also leads to a decrease conversion efficiency

10 and limits its use.

The purpose of the invention is to improve the use of current gates and the efficiency factor.

15

The goal is achieved by the fact that the AC-DC converter contains a rectifier and a power transformer with three groups of secondary windings,

20 of the first of which is connected to a star, the zero point of which forms one output terminal, and each of the first conclusions of the second and third groups is connected to the rectifier valve electrode, the other electrodes of which are combined and their common point forms the second output terminal, provided with a three-phase equalization reactor, windings which are located on one magician, a nitro line, and the middle point of each winding of the surge reactor is connected to the free output of the first secondary winding, the beginning of each half winding of the surge reactor connected to the corresponding second output of the third secondary winding, and the end of the other half winding of the surge reactor is connected to the corresponding second output of the second secondary winding, FIG. 1 shows a converter circuit; Fig. 2 shows diagrams of secondary linear voltages e, output voltages e, voltages at half of the reactor winding Uo, then for gates. The converter consists of a power transformer containing three groups of secondary windings 1–3 (primary windings not shown) of “equalizing reactor 4, made in the form of magnetic supply 5 with three windings 6–8, rectifier assembled on valves 9–14 , loads 15. Secondary windings of group I are connected in a star, and their free clamps a. respectively, they are connected to the middle points 0, 0, Oj of the windings 6-8 of the equilibrium reactor 4, while each phase winding of group 1 is connected to the opposite phase windings of the other groups through the half of the windings of the reactor. Thus, the phase winding of group 1a is through half of the winding 6 pea; ktora 0 /) Pu. connected respectively with opposite phase windings Cn. Phase windings b and c are connected in the same way. It is also necessary to observe the additional level in order to ensure the efficiency of the circuit, so that the same output of each reactor winding associated with this 1-star phase winding is connected to the opposite phase winding of groups 2 and 3, which follows the order of time. specified phase winding; This means that if, for example, the output p of winding 6 of the equalization reactor is connected to the next in order after phase a and phase b of group 2, then the outputs r and c of windings 7 and 8, which correspond to phases b and c, should blend, respectively, with the following in the forward order alternation of phases C, and a. The free output of each of the windings of groups 2 and 3 is connected to the anode of one of the valves 9-14. The cathodes of these valves are combined into a common point, which is one output terminal of the converter, the other output terminal of the converter forms the zero point O of the star. The principle of operation of the converter is illustrated by diagrams (Fig. 2 a-b), from which it can be seen that at a given time to the resulting voltage of two phase windings having a lower value, the voltage of half of the winding of the compensation reactor is added, and if the resulting voltage of two the windings matter more is subtracted (Fig. 2a). In this case, both half of the rector windings associated with this phase and half of the windings belonging to different phases can work. For example, the voltage of half of the reactor winding 7 is subtracted from the resulting voltage y, and the voltage OjS half of the reactor is added to the voltage in the interval of simultaneous parallel operation of phases c and a with phases b. Voltage at half. The windings of the reactor IR (Fig. 2, b) are constructed from the difference of the ordinates of the two resulting secondary voltages, for example, e, e, esa, etc. As can be seen from the diagram (figv), each of the valves 9-14 conducts for 120 h.grad, the amplitude of the current is equal to half the load current 1/2 d. The same current flows through each of the secondary windings 1 and 2. Each phase winding of group 1 conducts a current for 180 electr. degrees, of which 6p long. hail - full current Ja and 120 el. hail. - half current rear load 1/2 1d. The design power of the power transformer is 1.32 output Pgj, and the surge reactor is 0.1 Rd. It is obvious that the resulting typical power of transformer elements does not exceed the power of the transformer in the conversion scheme with the connection of the secondary windings into a double zigzag without an equalizing reactor. This was made possible by reducing the effective values of the currents flowing through all the windings of the transformer.

Thus, the proposal makes it possible to eliminate the main disadvantage of the known converter according to the double zigzag scheme — poor use of current gates, since the duration of the flow of the current increases to. hail. and the amplitude is reduced to 1/2 1a. The decrease in the effective value of the currents of the transformer windings together with the improvement in the anode current form of the valve is caused by the efficiency of the converter.

Claims (2)

1. Kaganov I.L. Electronic and 25 ionic transducers.M, -L., SEI, 1956, p.Sh, p. 127. 2. Rivkin G. A. Conversion devices. M ,, Energie, 1970, s.Z. P ed eof, feet ffci ffot f (Qi fe9t Cott fffft (ici A l A A / V v v v {pue.Z