SU365043A1 - AC CURRENT DEVICE - Google Patents

Description

one

The invention relates to electronics.

AC switching devices are known that contain a bottom bridge, the diagonal of which includes a resistor, a thyristor and a phase-shifting KS-chain, between which middle point and the thyristor adjusting electrode is turned on, and the resistor of the specified chain is shunted by a diode.

In order to reduce power consumption and increase stability of operation at high angles of starting the thyristor, in the proposed device, the resistor included in the bridge bridge is designed as a voltage divider, the output of which is connected to the midpoint of the phase-shifting / C-circuit through an additional diode.

The drawing shows a schematic diagram of the proposed device.

The switching device contains diodes / -6, diode thyristor 7, triode thyristor 8, capacitors I 0, resistors // - 16, chokes 17, 18 of the noise protection filter, output load resistor 19.

When applied to the input terminals 20, 21 of the alternating voltage, a two-period rectification is carried out by its diodes 1-4 connected to the Gretz bridge circuit. A pulsating two-hole sinusoidal pulse is applied positively.

thyristor anode 8 polarity and its cathode negative polarity. The same voltage simultaneously charges the capacitor 9 through resistors 12 n //. When the voltage on the capacitor 9 becomes equal to the threshold voltage of the diode thyristor 7, it turns on, and its resistance drops to several ohms in a time not exceeding one tenth of a microsecond. This means that the voltage of the capacitor .9 will almost instantly be applied to the control circuit of the thyristor 8, due to which the capacitor 9 through the limiting resistor 14 will deplete. Elementary

the discharge current of the capacitor 9 turns on the thyristor S and the rest of the half-cycle will receive a current through the load resistor 19, the magnitude of which is determined by the voltage across the resistance of the resistor 19. At the end of the discharge of the capacitor 9, the thyristor 7 is turned off.

When the voltage on the thyristor 8 becomes less than its residual voltage (about 1 in), the thyristor 8 turns off. This happens automatically at the end of the half wave.

sinusoidal waveform at an electric angle close to 180 °.

In the next half-wave sinusoidal voltage, the process is automatically repeated in the same way: the coi71 is charged, the sensor 9, the thyristors 7 and 8 are turned on, the capacitor 9 is discharged, the thyristor 7 is turned off, the load resistor 19 is connected to the input voltage In turn, the thyristor is turned off in the nolunernod terminal.

The current flowing through the load resistor 19 is controlled by varying the time of the remaining part of the linear voltage from the moment the thyristor is turned on 8 n until the end of the half-wave sinusoidal voltage. For this, it is necessary to set the desired resistance value of the alternating resistor 11 and thereby increase the time during which the capacitor 9 is charged before the switching on of the diode thyristor 7.

When adjusting in the resistor 19 small currents (the electric angle, for which thyristor 8 is turned on, is close to 180 °), it may turn out that charging the capacitor 9 is not enough to turn on the bottom thyristor 7. In this case, it is necessary to receive the next half-wave of the sinusondal the voltage to discharge the capacitor 9, since in the opposite case the next half period is negligible, recharge it and lead to the insertion of 7 to 8 thyristors at a low electric angle and, as a result, to the ambiguity and instability of the device operation .

In the proposed device, it is possible to ensure the stability of operation and a small amount of the consumed mosh.

When the half wave of a sinusoidal joint starts to fall off, the drop in voltage on the resistor 16 of the divider will be less than the voltage on the capacitor 9, which will cause a displacement of diode 6 in the forward direction and discharge of the detector 9 through the resistor 16. In addition, the capacitor 9 may even discharge through diode 5 and resistors 13, 15, 16. Therefore, the resistance of resistor 16 can be chosen small, and the resistance of resistor 15 can be significantly increased and thereby reduce the power consumption of the device.

The throttles 17, 18, together with the capacitor Yu, fulfill the function of the filter, preventing it from entering the high-frequency noise network when the thyristor is turned on 8.

Resistor 14 is illuminated in the case when the thyristor 8 can be destroyed by the initial discharge current of the capacitor 9 when the diode thyristor 7 is turned on.

Subject invention

Commuting, its AC device contains its diode bridge, the diagonal of which includes a resistor, a thyristor and a phase-shifting / C-circuit, between which middle point and control, a tyrnstor electrode, turn on the distor, and the resistor of the specified diode diode chain characterized by that, in order to reduce consumption of the mosh, to increase the stability of work at high angles of the thyristor,

the resistor included in the bridge diagonal is made in the form of a voltage divider, the output of which is connected to the midpoint of the phase-shifting / C-center through an additional diode.