SU683000A1 - Arrangement for blocking thyristors - Google Patents

Description

one

The invention relates to electrical engineering and can be used as a device for switching off thyristors in DC / DC converters.

Thyristor deactivation devices are known that generate pulses for switching off the working thyristor using a precharged capacitor connected in parallel to the choke (the primary winding of the impulse transformer) through a switching thyristor 1.

This device is not very useful due to the fact that the amplitude of the voltage across the switching capacitor when operating in idle mode (when two thyristor circuits are turned off) is several times higher than the voltage of the power source.

Closest to the proposed thyristor deactivation device, which contains a power supply circuit of a series of first drossels connected in series, two direct-shifted thyristors and a second switch, shunted by a chain of two successively connected reverse-biased diodes, the middle terminals of these circuits being connected via a capacitor, and the middle terminal the circuit of the diodes is connected through the third choke to the negative pole of the source

power connected through a capacitor to the anode of one nz diode.

The disadvantages of this device are low reliability and efficiency, due to the instability of the voltage on the switching capacitor during operation, and the uneven amplitude of the voltage of the output pulses due to asymmetry of the circuit.

The purpose of the invention is to increase the reliability of the device and equalize the amnlithic voltage of the output pulses.

To achieve this goal, a second capacitor, connected by one

the output to the positive pole of the power source, and the other to the junction of the charge throttle and the first capacitor connected by another output to the negative pole of the power source.

The drawing shows a schematic diagram of the proposed device.

The device contains capacitors 1 and 2. connected in series with the poles of the power source, charging choke 3, switching capacitor 4, a circuit of series-connected thyristors 5 and 6, in series with which are connected commutating chokes 7 and 8, diodes 9 and 10, and thyristors are mixed in

in the opposite direction, and the diodes in reverse.

The device works as follows.

When the thyristor 6 is turned on, the condisor 4 is recharged along the following circuit: thyristor 6, oselotka droplet 8, diode 10. This forms the following circuit: junction of capacitors 1 and 2, choke 3, diode 10, negative pole of the power source.

As at this moment, a large recharge current of the switching capacitor 4 flows through diode 10, it is shifted in the conducting direction. The throttle current 3 begins to increase, remaining, however, during a part of the optical side, small due to the large electromagnetic time constant of the throttle 3. When the switching current begins to decrease and becomes equal to the current of the throttle 3, the current of the diode 10 drops to zero and the diode 10 closes . In this case, capacitor 4 is recharged by value: thyristor 6, choke 8, capacitor 2, choke 3. At the time of locking the diode 10, due to a change in the re-charge circuit of switching capacitor 4, the throttle current can close along the circuit: choke 3, diode 9, the capacitor 1, in this case, the voltage amplitude on the choke does not exceed the voltage on the capacitor 1. When the recharging is completed, the current in the circuit reverses, the thyristor 6 is turned off.

In the next switching cycle, when the thyristor 5 is turned on, the switching capacitor 4 is recharged across the circuit: diode 9, choke 7, thyristor 5. Since diode 9 is open, choke 3 is connected to a power source and the current through it begins to increase. Having reached the maximum, the current begins to decrease and becomes equal to the throttle current, the diode 9 closes, and the recharging circuit of the capacitor 4 changes its structure. Perezar d occurs on the circuit: choke 3, capacitor 1, choke 7, thyristor 5.

When the thyristor 5 is turned off, the current of the throttle 3 is closed through the capacitor 2 and the diode 10.

Then all the processes are repeated.

It should be noted that the shorter the time of dropping 3, the earlier the diodes 9 or 10 are locked, the greater

part of the time, the power source is included in the switching circuit, and therefore, the greater the amplitude of the voltage on the switching capacitor 4. Due to the fact that one of the capacitors 1 or 2, the voltage at which is equal to half the voltage of the power supply, is not connected to the switching circuit The entire switching voltage, but only for a part of it, the voltage amplitude at the switching capacitor in the steady state is smaller than in known devices, which leads to a higher reliability of the device.

The symmetry of the switching circuits causes the amplitude of the voltage of different fields on the switching capacitor to be constant in both switching cycles and, therefore,

output pulse amplitudes.

Claims (2)

1.Labuntsov VA and. Autonomous inverters. M., “Energie, 1967, p. 121. 2. USSR author's certificate №448602, P 03 K 17/52, 1973. -Echf 4 - (