SU551776A1 - Power thyristor control pulse shaper - Google Patents

Description

one

The invention relates to the field of converting technology and is intended for use in control systems of thyristor converters for various purposes, in particular, high frequency converters for induction heating.

Output devices based on blocking generators and amplifiers with positive feedback l are known.

The closest in technical essence to the proposed are output drivers made on transistors with different types of conductivity with an RC feedback circuit of positive feedback L2j. Such circuits do not require a complex transformer, the transformer can be brought to the thyristor, the energy consumed by the shaper occurs only at the moment of formation of the output pulse, the duration of the output pulse is determined by

shaper, and control schemes possibly narrow pulses.

However, these schemes have a significant drawback - low noise immunity. Leads from the power source and

From the power circuit of the converter, due to the constant positive feedback, can lead to false positives of the devices.

The aim of the invention is to increase the noise immunity of the output driver on transistors with different types of conductivity and RC - circuit of positive feedback.

For this, the shaper is equipped with an additional thyristor, the cathode of which is connected to the base of one transistor, and the anode through a positive feedback circuit to the collector of the other transistor, with the anode of the thyristor connected to the cathode of the discharge diode.

The drawing shows the scheme of the proposed shaper.

The driver contains an input transistor 1 (ri-p-Ti type) and an output transistor 2 (pnp type), the load 3, which is the input windings of pulse transformers, a positive feedback circuit from a resistor 4 and a capacitor 5, limiting resistor 6 and two

bias resistor 7 and 8, as well as the discharge diode 9. The new element introduced into the driver is the thyristor 10.

When the input positive control pulse arrives, the control current of the thyristor 10 and the base current of the resistor 1 flow. The unlocking of the transistor 1 leads to the unlocking of the transistor 2. The output voltage from the load 3 flows through the circuit 5-1-10 to the transistor 1. The circuit The connection is closed and conditions are created for the fast (regenerative) unlocking of both transistors. In load 3, a rectangular pulse is generated. As a result of the charge of the capacitor 5, the reverse current decreases, this leads the transistor 1 and 2 out of saturation and leads to a fast (regenerative) locking of both transistors and the end of the pulse. Condenser 5 is discharged through load 3, diode 9 and resistor 4, and thyristor 10 is locked.

The use of an additional element, a thyristor, favorably distinguishes the proposed shaper from the prototype, since it completely eliminates the possibility of its triggering from the noise coming from the power source and load. As a result, the reliability of the transducers is increased, and the possibility of using a shape-changer in high-noise circuits is possible.

Claims (2)

1. Semiconductor rectifiers, ed. Kovalev D.I. and Mostkova N. M. Energi, 1967, p. 249. 2. The patent of Germany N 03 to No. 1932132, 1974 (prototype). ABOUT