SU1283911A1 - A.c.voltage-to-d.c.voltage converter - Google Patents

Abstract

The invention relates to a converter technique and can be used to power various DC consumers. The purpose of the invention is to simplify. In the converter, containing transformers 1 and 2 and valve bridges 7 and 8, the network windings 3, 4 and valve windings 5 and 6 are switched from the circuit to the circuit using switches 9-20. The twelve-pulse rectifying during switching is provided by performing one of the valve windings with taps, dividing it into parts in the ratio (1 - G3 / Z): / 3. 2 Il. stars-triangle and back § (L

Description

Yu

00 00

with

l-

112

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

The purpose of the invention is to simplify the device.

FIG. 1 is a circuit diagram of a converter; FIGS. 2a, b show the vector voltage diagrams at the inputs of the valve bridges.

The converter contains two three-phase two-winding transformers 1 and 2. The beginnings A1, B1, C1 and A2, B2, C2 of the network windings 3 and 4 of the transformers are connected to phases A, B, C of the mains, forming the input terminals. The beginnings a1, b1, c1 and a2, b2, c2 of the valve windings 5 and 6 of the transformers are connected to the AC inputs of three-phase valve bridges 7 and 8, respectively, connected in series with direct current DC transformer winding 6

2 is made in each phase with offsets x3, us3, z3, dividing it into small and large parts in the ratio

by: . ii

(1 - y):.

Between the ends x1, y1, z1 and the beginnings of B1, C1, A1 of the power winding 3, switches 9, 10 and 11, respectively, are connected. Between the ends of x2, y2, z2 and the beginnings B2, C2, A2 of the power winding 4 are turned on, respectively. , switches 12,13 and 14. Between the ends x1, y1, z1 and the beginnings b1, c1, a1 of the valve winding 5 switches 15, 16 and 17 respectively, between the ends x2, y2, z2 and the beginnings b2, c2 and a2 the valve winding 6 is included, respectively, switches 18, 19 and 20. Between the end zl and the ends x1 and y1 of the network winding

3, switches 21 and 22, respectively, are connected. Between the end of z2 and the ends x2 and y2 of the power winding 4, switches 23 and 24 are turned on, respectively. Between the ends of zl and the ends x1 and y1 of the winding switch 5 are turned on, respectively, switches 25 and 26 Switches 27 and 28 are switched on, respectively, between the tapping of the UZ and tapping of the x3 and z3.

The device works as follows.

When you turn on the switches 9-14, 18-20, 25-26 (the remaining switches

20

8391

five

 .

thirty

40

45

50

55

12

switched off) the network (terminals I and 4 transformers 1 and 2 are connected to the phases of the network A, B, C according to the triangle scheme and the ventilation windings 5 and 6 are connected according to the star and triangle schemes, respectively. The vent windings 5 and 6 create two equal-size systems current-generating EMFs shifted relative to each other by 30 e-hail, (Fig. 2). One system of current-generating EMF a1, b1, c1 (fig. 2a) is created by the valve winding 5 of the transformer 1 by geometric summation of the emf of adjacent phases valve windings. Another system is a topo-image (their emf a2, b2, c2 (fig 26) is created by the valve winding 6 of the transformer 2. Since the indicated emfs are shifted relative to each other by an angle of 30 degrees. (S 30 degrees. Degrees, the output voltage curve will correspond to a twelve-pulse rectification) with the average value of the voltage is Uj.

The output voltage is controlled by varying the thyristor control angles of valve bridges 7 and 8. As the thyristor control angles increase, the output voltage decreases, which leads to a decrease in the power factor. When the output voltage decreases, switches 18-20 and 25-26 are turned off, and switches 15-17.27-28 are turned on, which leads to the connection of valve windings 5 and 6, respectively, according to triangle and star schemes and the formation of two systems current-generating EMF a 1, 1, 1 and a 2, 2, 2, equal in magnitude and shifted relative to each other at an angle of el.grad (figure 2). The amplitudes of these EMF in -G below. amplitudes of emf of systems at, b1, c1 and a2, b2, c2. Switching to current-generating EMF systems а 1, 1, с 1 and а 2,, с 2 allows reducing the angles of control of the thyristors of the valve bridges 7 and 8, which leads to an increase in the power factor.

With a further increase in the angles of control of the thyristors and a decrease in the output voltage to Uj, the switches 9-14 turn off and the switches 21-24 turn on, which leads to the connection of the network windings 3 and 4 of transformers 1 and 2 according to the star circuit

Yes. In this case, the amplitudes of the emf of the valve windings 5 and 6 are reduced by a factor of ~ O, but the relative orientation of the linear emf of the winding windings relative to each other does not change. Therefore, the output voltage curve will also correspond to a 12-pulse rectification.

Instead of two transformers, one transformer with split windings can be used. This reduces the number of switches on the primary side by half.

t

Thus, the device allows stepwise regulation of voltages at the inputs of valve bridges while maintaining a 12-pulse rectification with a smaller number of switches and branches of the network and valve windings of the transformers.

Claims (1)

Invention Formula AC to DC converter containing two three-phase transformers with mains 11 4 and valve windings, two three-phase valve bridges, connected in series and twenty on-off. In this case, for the sake of simplicity, the input pins are formed by the beginnings of the network windings of each transformer, the end of each of the primary and valve phase windings is connected to the beginning of the winding of the subsequent phase winding through one of the twelve switches the end of one of the primary phases and the first 1-winding windings are connected to the ends of the other two phases through one of the six switches, the remaining two switches connect the outlet of one phase of the second valve winding to The wires of the two other phases, in this case, the outlets divide the valve winding in each phase into small and large parts in the ratio (1 - Gz / S), and the beginnings of each of the valve windings are connected to the AC input of the corresponding valve bridge. fpuz.f -S;: - p b l FIG. b l a t