SU944056A1 - Device for control of thyristorized ac voltage converter - Google Patents

Description

The invention relates to devices for controlling static converters, in order to obtain the 'required value of the output parameter, performed on semiconductor devices with a control electrode ⁵ , and can be used to measure voltage, and therefore, current on an active or inductive load included in the circuit _1Q supply through the thyristor, in particular for controlling the voltage on the coil of the electromagnet of the vibro-hopper of the microchip unpacking machine.

Closest to the proposed ₁₅ is a device for controlling a thyristor AC voltage converter, containing a phase-shifting chain of a series-connected capacitor and a resistor, one of the terminals of which is connected to the first terminal for connecting an AC voltage source, a threshold element and a pulse transformer, while the primary winding of a pulse transformer forms a series circuit with a threshold element, shunting capacitor P1.

However, such a device does not have a full range of phase shift control in the region of phase angles, i.e. 120 °.

The purpose of the invention is the expansion of the range of regulation.

This goal is achieved by the fact that the first diode and the node from the parallel connected capacitor and the second diode are additionally introduced, the first diode is connected in parallel with the phase-shifting capacitor, and the node from the parallel connected capacitor and the second diode is connected between the second terminal for connecting the AC voltage source and the other terminal phase shifting chain, while the anodes of the first and second diode form a common point.

This embodiment of the device allows you to expand the range of regulation of the phase shift of the control pulses from 0 ° to 180 °, at which there is a change in voltage and current at the load from Zero to the maximum value.

In FIG. 1 shows a circuit diagram of a device; in FIG. 2 - timing diagrams of stresses.

The device circuit includes a resistor 1, a variable resistor 2, a resistor 3, a variable resistor 4, a first diode 5, a capacitor 6, a second diode 7, a capacitor 8, a threshold element 9 (dynistor), a primary winding 10 of a pulse transformer 11, a secondary winding 12 of a pulse transformer , diode 13 of the output circuit, thyristor 14, load 15 · In this case, the resistors 1, 4 and the capacitor 8 form a phaeo-shifting chain. In FIG. 2 shows time diagrams of voltages 16 on a thyristor 14, voltages 25 on a capacitor 8, voltages 18 on a capacitor 7.

to

The device operates as follows.

When you turn on the power source (mains ~ 50 Hz, 220 V), the voltage is? is given to the closed thyristor 14 through the load 15 and to the input of the device, at which the capacitors 6 and 8 are charged and discharged. In the positive half-period of the voltage amplitude of the power supply, the polarity and discharge of the capacitor 6 are changed through resistors 2,3 and 4 and capacitor 8. V the initial discharge period of the capacitor 6, the diode 5 is closed, since the potential at the cathode of the diode 5 is greater than the potential at the anode of the latter, at which the charge of the capacitor 8 from the power source is delayed. Subsequently, as the capacitor 6 is discharged, the positive potential at the anode of the diode 5 and the voltage amplitude at the capacitor 8 increase from the power source through resistors 1 and 4, and the capacitor 6 is discharged before the maximum voltage amplitude across the capacitor 8 is reached. In the negative half-period of the source voltage power is the discharge of the capacitor 8 and the charge of the capacitor 6.

! 4

When the capacitor 8 is discharged through the resistors 4, 2, 3 ”, the capacitor 6, the diode 7 is closed, and the voltage amplitude at the capacitor 6 is delayed. Further, as the voltage amplitude at the capacitor 6 increases, the voltage amplitude at the capacitor 8 decreases, and the last occurs in time before reaching the maximum value of the amplitude of the voltage across the capacitor 6. Next, the process of discharge and charge of the capacitors 6 and 8 in each of the half-periods is similarly repeated, and the amplitude is on the capacitor 8 with respect to the amplitude of the voltage at the anode of the thyristor 14 phase lags by about 90 el. degrees, and the voltage amplitude on the capacitor 6 lags in phase with respect to the amplitude of the voltage on the cathode of the thyristor 14 by about 90 el.

When the resistance of the alternating voltage of the resistor 4 decreases, the voltage amplitude at the capacitors 6 and 8 increases. The voltage amplitude at the capacitor 8 will increase until it reaches a value slightly higher than the value of the amplitude of the switching voltage of the dinistor 9 · During the inclusion of the dinistor 9 in the conducting state the polarity changes on the capacitor 8 at zero voltage on the capacitor 6. When the dynistor 9 is turned on, a current from the source voltage through resistors 1 and 4 and the discharge current of capacitor 8. As the capacitor 8 discharges, the current in the discharge circuit increases, reaching a maximum value with a minimum voltage across capacitor 8. At this moment, the polarity on winding 10 changes, the current of which changes direction and closes the circuit of the dinistor 9 and the capacitor 8. When changing the polarity, the resistors 1 and 4 and the diode 5 are recharged through a voltage amplitude equal to the voltage drop across the dinistor 9 in the open state. In this case, the current flowing from the power source through resistors 1 and 4 is greater than the sum of the holding currents of the dinistor 9 in the open state of the charge current of the capacitor 8. The dinistor 9 remains open until the end of the positive voltage amplitude of the power source. When the current flows from the power source and the discharge current of the capacitor 8 through the winding 10, a control pulse is formed in the secondary winding with a steep leading edge flowing through the diode 13 to the control circuit of the thyristor 14, opening the latter. When the thyristor 14 is opened, a current flows through the load 15 into the positive half-period of the power supply voltage, forming a voltage drop at the load 15 equal to the difference between the voltage of the power source and the voltage drop across the thyristor 14. The negative half-period of the voltage of the power source occurs from 10

IS

944056 6 the increase in the number of pulses in the control circuit of the thyristor 14 occurs in the positive half-period of the mains voltage following each other after approximately 10 electrical degrees, and the first control pulse is out of phase by 480 electrical degrees. relative to the voltage in the positive half-cycle of the voltage at the anode of the thyristor 14. Simultaneously with an increase in the number of control pulses, a voltage shift occurs at the capacitors 6 and 8 and a decrease in the charge and discharge time of the latter. Therefore, the inclusion of a diode 7 and a parallel diode-capacitive circuit, consisting of a diode 5 and a capacitor 6, extends the range of regulation of the phase shift of the control pulses within 0-180 electric degrees, changing the polarity and discharge of the capacitor 8. and changing the polarity and charge of the capacitor 6 to the maximum value. Subsequently, at a constant value of the resistance of the variable resistor 4, the process of switching on and off the dinistor 9 is repeated. When the resistance of the variable resistor k decreases, a phase shift occurs relative to the voltage at the anode of the thyristor 14 of the control pulse in the control circuit of the latter, at which a smooth increase in voltage, and therefore current, occurs at the load 15. At the same time, the amplitude increases. voltage on the capacitors 6 and 8 and a decrease in the charge and discharge of the capacitor 8 and 6, and the discharge of the latter occurs earlier than the charge of the capacitor 8. With a further decrease in the resistance of the variable resistor 4, the voltage across the capacitor 8 increases to the amplitude of the switching voltage of the dynistor ₄₅ Thus, at a certain value of the resistance of a variable resistor due to an increase in the amplitude of the voltage across the capacitor 8 into a positive half-period of the voltage of the power source in the control circuit, two pulses, the first being phase shifted by 70 degrees. with respect to the voltage at the anode of the thyristor 14. When the resistance of the variable resistor 4 is reduced to a minimum value (approximately to zero value), therefore, it smoothly changes the current (voltage) at the load from zero to maximum values. The variable resistor .2 and resistor 3 are connected in connection with the variation in the voltage of the inclusion of the dynistors in order to establish, at a constant maximum value of the resistance of the resistor 4 at the load 15 of zero voltage. The number of pulses generated in the control circuit of the thyristor 14 depends on the turn-on voltage of the dynistor 9, the lower the turn-on voltage of the latter, the more control pulses and vice versa.

The proposed device provides a wider range of regulation compared with the known.

Claims (1)

1. USSR author's certificate V 296209, cl. H 02 R 13/16, 1971.