SU1501229A1 - A.c. to a.c. variable voltage converter - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to ensure the symmetry of the voltage on the load and to simplify control. When the device is connected to the mains, a relaxation RC generator starts operating, in which capacitor 19 is charged through an adjustable resistor 20 with a full-wave leading current flowing through the emitting diodes of the photo thyristors of the thyristor optocouplers 1 and 2. When the voltage on the capacitor 19 reaches the threshold voltage element 18, the capacitor 19 is discharged and the emitting diodes of the photo thyristors of the thyristor optocouplers 1 and 2 are de-energized. As a result, adjustable pulses are applied to the load 4 in the form of a series of synchronous periods of mains voltage. 3 hp ff, 5 ill.

Description

SP

ND N5

WITH

The invention relates to electrical engineering and can be used to regulate the average power on an AC load with synchronous connection to the network.

The purpose of the invention is to ensure the symmetry of the voltage on the load and to simplify control.

FIG. Figure 1 shows a schematic diagram of a variable voltage to alternating voltage converter; in fig. 2,3,4 is an embodiment of its adjustment unit.

The device contains a controlled valve element in the form of thyristor optocouplers 1 and 2, connected in parallel, the first output of which is connected to the first output for connecting the network 3, and the second output connected to the output for connecting the load 4. To the second output for connecting the network 5 connects the remaining lead to connect the load 4 and the first leads of the first capacitor 6 and the first resistor 7, the second leads of which are connected to the first lead to connect the AC voltage of the single-phase rectifier bridge 8, and An alternating current output of bridge 8 is connected to an output for connecting network 3. Parallel to the alternating current terminals of a single-phase rectifying bridge 8, a series circuit consisting of a first diode 9 and a second diode 10 and a radiation source of thyristor optocouplers 1 and 2 is connected, the anode of the first diode 9 is connected to the first AC output of a single-phase rectifying bridge 8, the cathode of the first diode 9 is connected to the anode of the emitting diode of the photo thyristor of the thyristor optocoupler 1, the cathode of which is connected to the cathode of the emitting the diode of the thyristor optocoupler photothyristor 2, the anode of the latter is connected to the cathode of the second diode 10, and the anode of the second diode 10 is connected to the second AC output of a single-phase rectifying bridge 8. The control unit 11 connected by its first output 12 to the output of the measured single-phase voltage rectifier bridge 8 with positive polarity, the second output 13 to the common point of the cathodes of the emitting diodes of the photo thyristors of the thyristor optocouplers 1 and 2, and the third

0 5 about 0 5

five

0

five

by wiring 14 to rectifying the rectified voltage of a single-phase rectifying bridge 8 with negative polarity, includes a second resistor 15, a third resistor 16 and a quarter resistor 17, a key element 18, a second capacitor 19 and a variable resistor 20, the first output of the second the resistor 15 is connected to the first output of the key element 18, the second output of which is connected to the first output of the third resistor

16 and forms the first terminal 12 of the control unit 11, the second terminal of the third resistor 16 is connected to the first terminal of the fourth resistor 17 and the first terminal of the second capacitor 19, the second terminal of which is connected

with the first output of the variable resistor 20, with the second output of the second resistor 15 and forms the third output 14 of the control unit 11, and the second output of the fourth resistor 17, the moving contact and the second output of the variable resistor 20 are combined and form the second output 13 of the control unit 1 t.

FIG. 2 shows the circuit of the control unit 11, in which sequentially with a quarter resistor

17, a third diode 21 is introduced, due to which the second capacitor 19 can only be discharged through the circuit containing the key element 18, which increases the duration of the pause and makes it independent of the value of the input resistance of the variable resistor 20.

FIG. 3 shows the circuit of the control unit 11, in which the fourth diode 22 is inserted in series with the third resistor 16, due to which the charge of the second capacitor 19 can only be through the second output 13 of the control unit 11, i.e. when charging the second capacitor 19, all the current bounded by the first K1-1N capacitor 6 and the first resistor 7 flows through the emitting diodes of the photo thyristors of the thyristor optocouplers 1 and 2.

The third 21 and fourth 22 diodes, introduced into the regulation block It (FIGS. 2 and 3), in a number of cases of converter implementation, significantly improve its characteristics depending on the required adjustment range, pulse duration and pause, and characteristics of the used thyristor rptron (n 1, 2,

five

FIG. 4 1 and kacha) 1a t: xcMa of the control unit 11, g Koropofi third Resistor 1 f 1 now ii and variable as pt siinop, -i and Mo contact is connected to; 1 (1 pinch; with ps repair; resistofl In this case, the range of regulation of the transducer by the converter is dissipated, because with a simultaneous 1 ncm, the resistance of the first resistor 20 and resistor 1b increases, the charging current of the second capacitor 19 increases, i.e. its charging time decreases, and discharge time is increased and the inverter operates with decreasing duration applied to the load the voltage following the pause increasing in duration and vice versa.

FIG. Figure 5 shows timing diagrams explaining the operation of the device, where diagram 23 is the voltage across the load 4 during voltage regulation, diagram 24 is the line voltage and current in the first capacitor 6, diagram 25 is the voltage on the fourth resistor 17 and second capacitor) 9, diagrams 26, 27 are, respectively, t {k, flow through the second 13 and first 12 outputs of the control unit 11, diagram 28 is the voltage across the load.

The device works as follows.

in a way.

When locked key element

18 (for which, for example, a dynistor is used) in the control unit 11, the current flows from the second terminal 13 to the third terminal 14 along two parallel chains: a series soy; a fourth fourth resistor 17 — a second capacitor 19 — a variable resistor 20 from the first terminal 12 - to the third pin 14 - through the third resistor 1b and the second capacitor 19 with a chain parallel to it: from the fourth resistor 17 - the replaceable resistor 20. At the same time, most of the current limited by the first capacitor 6 and the first resistor 7 flows through Light diodes of the photo thyristors of the thyristor optocouplers 1 and 2, including their synchronous each half-period, and charge the capacitor 19 until the voltage on the key ground 1te 18 reaches its threshold value; and it will not open.

; m, 6

When open to, -chem "ohm HTt-IF. the current into the regulator;: 1 and 1 1 postuni ci only through its perryp pin 12, as the second resistor 1j is designed to limit (current increase when unlocking the key element 18 and the resistance between the first 12 and the third 14 of the output n block register 11 MN01CH1 low resistance between its third 13 and fourth 14 pins. The current through the emitting diodes of the thyristor optocouplers 1 and 2 is discontinued, and the second capacitor 19 is discharged through two parallel terminals, the first: through the third resistor 16 - open the key element 18 - the first resistor 15 and the second: h Through the fourth resistor 17 and the variable resistor 20. The open state of the key element 18 and, consequently, a pause in the operation of the converter (photo thyristors of the thyristor optocouplers 1 and 2 are locked) continues until the lock-in} of the key element 18.

Through the key element 18 a current flows, which has two components: decreasing exponentially from the discharge of the second capacitor 19 and a pulsating half-wave limited by the first capacitor 6 and straightened; a single-phase rectifying bridge 8. Locking of the key element 18 is possible when the current in it becomes less than the holding current, i.e. in moments when the pulsating component is close to zero. From this point on, the current begins to flow into the emitting diodes of the photothyristors of the thyristor optocouplers 1 and 2, starting with the one on which the anode voltage is negative at that moment, which ensures synchronous switching.

A change in the resistance value of the variable resistor 20 changes the amount of current charging the second capacitor 19 and, to a lesser extent, the discharge current, therefore, the duration of the on and off state of the photo thyristors of the thyristor optocouplers 1 and 2 is controlled by the variable resistor 20. With a small value of the variable resistance the resistor 20, the voltage on the second capacitor 19 does not reach the threshold voltage value of the key element 18, and the photo thyristors of the thyristor optocouplers 1 and 2 are constantly switched on.

Claims (4)

1. Adjustable AC-to-AC converter, containing a controlled valve element with double-sided conductivity connected in series with the load to the terminals for connecting the network, a series circuit from the first capacitor and the first diode, the first resistor connected in parallel to the first capacitor, the second capacitor, the key element made in the form of a threshold element, the second diode and the second resistor, while the first output of the first capacitor is connected to a common output point for connecting the load and the first output to connect the network, the second output of the first capacitor is connected to the anode of the first diode, the anode of the second diode is connected to the common point of the remaining output to connect the network and the first output of the controlled valve element, the second output of which is connected to the second output to connect the load The first terminal of the key element is connected to the first terminal of the second resistor, which is distinguished by the fact that, in order to ensure the symmetry of the voltage on the load and to simplify the control, the controlled valve The first element is designed as two anti-parallel connected thyristor optocouplers, a single-phase input bridge, a third and fourth resistors and a control variable resistor are inserted, the second output of the key element is connected to the positive output of the single-phase rectifying bridge and the first output of the third resistor, the second the output of which is connected to the pen five 0 five 0 five 0 the second terminal of the fourth resistor, the second terminal of the second capacitor is connected to the second terminal of the second resistor, the first terminal of the variable resistor and the negative terminal of a single-phase rectifier bridge, the terminals for connecting AC1) are alternating current connected to the anodes the first and second diodes, the cathode of the first diode is connected to the anode of the emitting diode of the first thyristor optron, the cathode of the second diode is connected to the anode of the emitting diode of the second thyristor o optocoupler, and the cathodes of the emitting diodes of the thyristor optocouplers are combined and connected to the second output of the fourth resistor and to the moving contact and the second output of the variable resistor. 2. A converter according to claim 1, characterized in that a third diode is inserted, the anode of which is connected to the first terminal of the fourth resistor, and the cathode is connected to the common terminal of the third resistor and the second capacitor. 3. The converter according to claim 1, wherein the fourth diode is inserted, the cathode of which is connected to the second terminal of the third resistor, and the anode is connected to the common terminal of the fourth resistor and the second capacitor. 4. The converter according to claim 1, wherein the third resistor is embodied as a variable resistor, wherein the movable contact is connected to the common terminal of the fourth resistor and the second capacitor and is mechanically connected to the movable contact of the first herdshift resistor . one} Fi9.2 Menf irfHuf efiru Fal. Fm.ch / | .. J, looking. /1.1 PG If l / l / l / v 1 (1 Ofnnvfiaieu / rf yeit rtuneff 7i SffKf tXfSSmS r f YYYYY (.