SU928566A1 - Ac-to-ac voltage converter - Google Patents

Description

The invention relates to a conversion technique and can be used to convert an alternating voltage into an adjustable pulse. A device for adjusting the voltage with a thyristor control is known, which contains a transformer, the secondary winding of which recharges the capacitor and unlocks the thyristor magnetic amplifier, by changing the bias Current in the control winding of which the ji unlocking angle is controlled. Such devices are complex in design due to the presence of a magnetic amplifier and an additional transformer, and do not contain a regulator of the frequency of the excited oscillations. The closest to the technical essence of the present invention is an alternating voltage-to-alternating voltage converter containing 1DI connected between an input and output output of a thyristor key, a relaxation pulse generator containing, in the control circuit of a thyristor switch, a dynistor, a capacitor, one of the outputs which is connected to the anode of the dynistor and the output of the movable contact of the variable resistor and the locking diode 2. The disadvantages of this device are the design complexity due to and two limiting diodes, a step-down transformer and a shunt resistor, the heating of which changes the mode of operation of the semiconductor elements and the device as a whole low efficiency, due to losses on the shunt resistor (especially at low frequencies of the device) and in the step-down transformer except Moreover: it does not contain an oscillation amplitude regulator. The purpose of the invention is to simplify the design, increase the PDC, provide autonomous control of the amplitude and frequency of the oscillations being excited.

This goal is achieved by inserting a resistor block and a switch into the device, while one or more of the resistor block leads is connected to a variable resistor, the other lead of the resistor block is connected to the cathode of the blocking diode, the anode of which is connected to the common point of the thyristor switch and the output pin. , and the common point of the cathode of the thyristor key and the input terminal is connected to another terminal of the capacitor.

The drawing is a schematic diagram of the proposed device for powering an electromagnetic vibration exciter.

The device contains a magnetic core with a winding 1, which is the load of the converter connected to the AC source 2 via a thyristor switch 3, the cathode of which is connected through capacitor 4 to the connection point of the anode of the distor 5 and the moving contact of the variable resistor 6. The second end of the variable resistor 6 is through one of resistors of the resistor block 7 is connected to the cathode of the blocking diode 8.

The device works as follows.

In each positive half-cycle of the emf of the alternating current source, the capacitor k is charged through the blocking diode 8, one of the resistors of the block 7, the variable resistor 6 until the switching voltage of the dynistor 5 is switched on and discharged through the control switch of the thyristor switch 3. The discharge current pulse opens the thyristor switch and a current is flowing through the excitation winding 1 causing the electromagnet to operate. With the disconnect of the dynistor, the next wind up and the capacitor occurs. The working phase of the thyristor key and the dynistor is in-phase matched, which allows you to adjust the amplitude and frequency of the output signal. The value of the operating voltage on the winding is regulated by changing the moment of supplying the control signal relative to the beginning of the positive half-cycle of the supply voltage, which is done by varying the charging current of the capacitor k with a variable resistor 6. The amplitude controller sets the Unlock Time Ich within O - 0, 01 s, i.e. thyristor opening phase - 0-180. At a phase close to O, the amplitude of oscillations is maximum, and when approaching 180, it is minimal.

The oscillation excitation frequency is controlled by connecting certain values of the resistors from block 7, in which the resistors are selected so that they switch to obtain frequency steps: 50; 25; 16.7; ...; 50 / n Hz, where p 1,2,3 ... indicates the number of positive half cycles of the source emf required to charge the capacitor before the switching voltage of the dynistor and then triggering the electromagnet.

For each frequency level, there is a range of resistance values consisting of the sum of a specific resistor from block 7 and the value of variable resistor 6. The values of resistors from the block are chosen so that the fully entered (core amplitude minimum) or variable (maximum amplitude) variable resistor cannot switch the frequency level.

If it is necessary to operate the vibration exciter, for example, at a frequency of t6.7 Hz (), it is necessary to switch the resistance switch 7 on the resistor unit so that the capacitor A of the dose emits at every third positive half-period of the source EMF before the switching voltage of the dynistor 5.

A variable resistor 6 adjusts the amplitude of the oscillation of the core, i.e. adjustment of the thyristor on-phase relative to the beginning of the positive half-period of the emf of the supply voltage.

The proposed device allows to simplify the design, reduce the size, due to the absence of a step-down transformer, a shunt resistor, two limiting diodes, increase the efficiency due to the absence of a shunt resistor and step-down transformer, as well as provide autonomous control of amplitude and frequency;

Conducted testing of the device layout at frequencies of the core in the range of 1.0–5.0 Hz confirmed the above advantages.

Claims (2)

1. USSR author's certificate number 181885, cl. G 05 D 15/01, 1973. 2. USSR author's certificate number 616137, cl. B 28 B 1/08, 1976.