SU1690128A1 - Device for control over ac voltage - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to simplify, reduce weight and size, increase reliability and efficiency. The voltage on load 14 is controlled by two transformers 1 and 2 by partially shorting the secondary windings using keys 3 and 4. Depending on the on-state duration of one or the other A key occurs in varying degrees of increase or decrease in voltage. Circuits And 5, 6 are triggered by zero-points 10 or 11 through a delay block 12 or 13, depending on the polarity of the signal from sensor 9 of the control signal. The signal of the latter is transmitted to the pulse shaping unit 7 of adjustable duration via the rectifier 8, thereby achieving the set goal. 1 з.п f-ly, 3 ill.

Description

The invention relates to electrical engineering.

The purpose of the invention is to simplify, reduce weight and size, increase reliability and efficiency.

Figure 1 and 2 shows the options for the device; FIG. 3 shows the rectified characteristic of the control signal;

In Figures 1 and 2, transformers 1 and 2 are connected in series by primary and secondary windings. The latter are included in the opposite direction. Two switches 3 and 4 of alternating current are connected in series with each other and connected in parallel to the secondary windings of transformers 1, 2. The control inputs of switches 3 and 4 are connected to the outputs of the AND 5, 6 circuit, the inputs connected to the pulse-forming unit 7 of adjustable duration, whose input The driver 8 is connected to the output of the control signal sensor 9. The latter, through chains composed of sequentially connected zero-bodies 10, 11 and delay blocks 12.13, is connected to the second inputs of circuits 5, 6. A load 14 is connected to the output of the device.

1, the common points of the secondary windings of the transformers 1, 2 and the keys 3,4 are combined. In FIG. 2, this connection is made by means of a non-linear reactor 15, and the keys are made triac.

The device works as follows.

With full shunting of one of the secondary windings, the voltage across the load rises, and when shunting the other, it decreases. In each adjustment sub-range, the degree of voltage change (increase or decrease) is adjusted by changing the relative duration of the on, off key condition. The change in the duration of the trigger pulses is performed by block 7. The regulation of this pulse duration

SP

WITH

С О О О

Jo

00

carried out by the signal from sensor 9, the output two-pole voltage of which varies in magnitude and sign. Depending on the polarity of the voltage at the output of sensor 9, one of the zero organs 10 or 11 is switched on, which through the corresponding circuit 6 or 5 permits the passage of pulses to one of the keys 3. 4. Rectifier 8 converts the control signal into one signal sign, i.e. provides a characteristic of the type of FIG. In this case, block 7 with a zero input signal does not generate pulses at the output. Delay blocks 12, 13 provide a delay of 10, 5 ms (for thyristors) when switching from one mode of operation to another (when an input signal appears), i.e. when changing the number of the included key. When the signal disappears, there is no delay. If the keys are 3 and 4 transistor, the delay is reduced to 10 µs. The delay ensures the reliable shutdown of the previously working key before switching on the other. This eliminates the short circuit mode.

Claims (2)

When keys 3, 4 are executed in the form of symistors (FIG. 2), it is advisable to introduce into the scheme a nonlinear reactor 15 that provides a current delay for a time equal to the off time, thus ensuring reliable triac off of triacs at the moment of current zero crossing. Claim 1. An alternating voltage control device comprising two transformers, the primary windings of which are connected in series between the terminals for connecting the power source, and the secondary windings - counter-sequentially and form a series circuit with the terminals for connecting the power source and the terminals for connecting the load, in addition, two AC keys, the control signal sensor and a pulse shaping unit of adjustable duration, characterized in that, in order to simplify, reduce IS and dimensions, increase reliability and efficiency, two schemes have been introduced the driver, two zero-organs and two delay blocks; each of the AC switches shunts the secondary winding of the corresponding transformer; the output of the control signal sensor is connected to the rectifier input and the zero-organs inputs; the output of each zero-organs is connected with the first input of the corresponding circuit AND, the output of which is connected to the control input of the corresponding AC switch, the output of the rectifier is connected to the input of the pulse shaping unit of adjustable duration, output which is connected to the second inputs of schemes IV 2. The device, according to claim 1, is such that triacs are applicable as AC keys, and the nonlinear reactor introduced into the circuit is included between their common point and the common point of the secondary windings of the transformers. FIG. 2 FIG.