SU1436235A1 - Direct frequency doubler - Google Patents

Description

(21) 4171745 / 24-07

(22) 12/05/86

(46) 11/07/88. Bul № 41

(71) Broshnevsky experimental plant "Lesdrevmash"

(72) C. M. Sasin and T. B. Lagoida

(53) 621.314.27 (088.8)

(56) USSR Author's Certificate No. 1089735, cl. H 02 M 5/16, 1983.

USSR Author's Certificate No. 1091287, cl. H 02 M 5/27, 1982.

USSR Author's Certificate No. 1312704, cl. H 02 / M 5/27, 1985.

(54) DIRECT DUAL FREQUENCY DOUBLE

(57) The invention relates to a converter technique and can be. used in the development of sources of secondary power supply electric planing, milling and grooving woodworking machines. The goal is to increase efficiency. The device contains two bridges on thyristors 1-8 and a matching power tr-p 9, to the winding 12 of which a load 13 is connected. Four impulse drivers (PI) 22 are connected to ballast resistors 20, 21 and the AC terminals of the bridge. FI 22 consists of a pulsed power transistor 23, a transistor 26 is connected to the winding. An output pulse power transducer is connected to the collector of transistor 26. The use of diodes 14-17 in the input circuits of FI 22 reduces losses on the ballast resistors by almost two times. 5 il.

WITH

s

1211

(L

 -W 13

-ntr

Sul

iy

00 O5

with

ate

YagG

Ha.fu3

The invention relates to power converter technology and can be used in the development of sources of secondary power supply for electric motors of planing, milling and grooving woodworking machines.

The purpose of the invention is to increase the efficiency of the converter.

FIG. 1 is a schematic diagram of a direct frequency doubler connected to the corresponding voltages of a three-phase four-wire network; .on FIG. 2 - voltage diagrams at the input of the doubler and one of the thyristors, as well as the current diagram of the same thyristor; in fig. 3 and 4 are the diagrams of the input and output currents of one of the control pulse formers, respectively; in fig. 5 is a plot of the output voltage of the converter.

The frequency doubler contains the first bridge on thyristors 1-4 and the second bridge on thyristors 5-8, the matching power transformer 9 with two primary windings 10 and 11 and one secondary winding 12 to which the load 13 is connected. In winding 11, V rzz has more turns compared to the winding 10. In the diagonal of the alternating current, diodes 14-17 are connected anti-sequentially, the junction points of which (cathodes) through the first ballast resistors 18 and 19 are connected to the negative poles of the bridges. The second ballast resistors 20 and 21 are connected to the positive poles of the bridges.

Four pulse shapers 22 are connected by one pole to one of the second ballast resistors, and the second input pole to one of the AC poles of the respective bridge. Each of the impulse drivers 22 consists of a first pulse transformer 23, the primary winding of which, connected in series with the diode 24 and in parallel with the zener diode 25, constitutes the input circuit of the driver. To the secondary winding of the first pulse transformer included emitter-base transition transmax. At this point, the thyristors 2 and 4 are opened, the voltage Uy on them decreases to zero (Fig. 2) and a current pulse ir through the circuit from the pole B through the thyristor 4 to the transformer primary winding 11, 5 then through the thyristor 2 and into the pole C In the secondary winding of the transformer 12, a positive voltage half-period is formed (Fig. 5).

Since the load is inductive, the IT current is lagging in phase from the voltage. The magnitude of the angle, during which the current i is still positive with a negative value, depends on the ratio of the inductive and active resistances of the load. voltage Ug. At the moment of the current termination ir at an angle equal to, the thyristors 2 and 4 close and a reverse voltage appears on them. When this starts to flow current i (Fig. 3) from the pole of the network through the diode 15, the first ballast resistor

20 18, the primary winding of the power transformer, the second ballast resistor 20, then through the diode 24, the primary winding of the first pulse transformer 23 and into the network pole B. At the same time, the transistor 26 from 25 lies on the primary winding of the second pulse transformer 27 from the DC source current will flow from the secondary windings of the same transformer to the control electrodes of the thyristors 6 and 8 of the second bridge; pulses of current i (Fig. 4) and they will open. This will occur at the moment when the voltage Uo passes its positive maximum. In this case, a negative half-period of the secondary voltage Ug is formed on the windings of the power transformer 9. Next in time

35

f5r- + o

similarly, the thyristors 1 and 3 of the first bridge are opened, and then at the time of 23 + oC thyristors 5 and 7 of the second bridge. After this, the cycle is repeated. Thus, in one input voltage period, two voltage periods Uj are formed at the output of the converter.

If the nature of the load changes during operation, for example, it will become more

of the resistor 26, to which the collector is actively connected (which usually occurs when the primary winding of the second output load is injured), then this will decrease yrnajj, and automatically, respectively, the angle of vol. At the same time, the effective value of the output voltage will increase, 50 since, as the load decreases, the voltage will also automatically decrease.

The values of the resistances of the first ballast resistors from the condition of minimum energy losses in them must be equal to the resistances of the corresponding second ballast resistors and are determined by the formula

t - in. 1/3

 2.G

pulse transformer 27, two secondary windings of which are connected to control electrodes of two diagonally opposite thyristors of the corresponding bridge.

The Converter operates as follows.

Suppose that the load 13 has an active-inductive character. Let's start the review

rhenium from an angle equal to V + ot when the UBC voltage has passed through a positive

maximum. At this moment, the thyristors 2 and 4 are opened, the voltage Uy on them decreases to zero (Fig. 2) and a current pulse ir through the circuit from the pole B through the thyristor 4 to the primary winding of the transformer 11 flows, then through the thyristor 2 and into the pole C. In the secondary winding of the transformer 12, a positive voltage half-cycle is formed (Fig. 5).

Since the load is inductive, the IT current is lagging in phase from the voltage. The value of the angle, during which the current i is still positive with an already negative voltage Ug, depends on the ratio of the inductive and active resistance of the load. At the moment of the current termination ir at an angle equal to, the thyristors 2 and 4 close and a reverse voltage appears on them. When this starts to flow current i (Fig. 3) from the pole of the network through the diode 15, the first ballast resistor

0 18, the primary winding of the power transformer, the second ballast resistor 20, then through the diode 24, the primary winding of the first pulse transformer 23 and into the pole of the network B. At the same time, the transistor 26 from 5 lies on the primary winding of the second pulse transformer 27 from the DC source current will flow from the secondary windings of the same transformer to the control electrodes of the thyristors 6 and 8 of the second bridge; The current pulse current i (Fig. 4) and they will open. This will occur at the moment when the voltage Uo passes its positive maximum. In this case, a negative half-period of the secondary voltage Ug is formed on the windings of the power transformer 9. Next in time

five

f5r- + o

similarly, the thyristors 1 and 3 of the first bridge are opened, and then at the time of 23 + oC thyristors 5 and 7 of the second bridge. After this, the cycle is repeated. Thus, in one input voltage period, two voltage periods Uj are formed at the output of the converter.

If the nature of the load changes during operation, for example, it will become more

45 is active (which usually occurs with an increase in load), then this will lead to a decrease in% - the amplitude of the corresponding input voltage.

Zener diode 25 facilitates the operation of pulse shapers, since in its absence the current i would flow through the primary winding of the transformer 23 in the period from to the 2nd (Fig. 3, dotted line). In the same area, two current pulses L (Fig. 4) are sent to the control electrodes of the thyristors b and 8, which do not change the state of these generators, as at time 5 (/ 4 these thyristors are open, and at the time preceding 2 (L, impulse iu is negative, the voltage Uj is also negative here.

FIG. 2, the thick solid line depicts the voltage diagram on thyristors 2 and 4 without losses, i.e. leakage currents of closed and direct voltages of open valves of the circuit, therefore, in the section from O / 2 + szs to Ji - Luz and 0; in the area from 35Г / 2 + оС to U-j- UgL, and in the remaining areas

t uee-kui. Ur-2

where K is the transformation ratio between windings 11 and 12. On the other thyristors, similar voltages occur, which are shifted in phase by a quarter of the voltage period of the supply mains. On thyristors of the second bridge, the magnitude of the voltages is about / times less than the corresponding instantaneous voltages of the first bridge.

.//.

ffC

0

five

0

The control pulse widths equal to oC-DCs depend on the opening time of the corresponding thyristors and are very small, therefore the corresponding pauses between the half periods of the output voltage U; almost invisible.

The use of diodes 14-17 in the input circuits of the pulse shapers almost halves the losses on the ballast resistors, as a result of which the overall efficiency of the proposed device is increased.

Claims (1)

Invention Formula A direct frequency doubler containing two thyristor bridges, the AC outputs of which form the power input terminals for connection to a two-phase AC network, and the DC outputs through the matching transformer in the corresponding polarity are connected to the output terminals, two ballast resistors and a block control, made in the form of four pulse shapers, providing interdependent control of bridge thyristors, characterized in that, in order to improve efficiency, it is equipped with two chains A series of oppositely connected diodes included in the diagonal of the alternating current of the bridges, and the junctions of the diodes of each chain through the ballast resistors are connected to one of the terminals of the direct current of the bridges of the same polarity. W sh (rig 2 (.6