SU372625A1 - VOSOOY8101-1 RCT - Google Patents

Description

one

The invention relates to the field of converter technology and is intended to convert a constant voltage of one level into a constant voltage of another level in power lines, contact networks and other systems.

DC converters are known that contain a thyristor inverter, a rectifier connected at the output of the inverter transformer, and a smoothing filter.

In such inverters, the filter is made in the form of a capacitor connected directly at the output of the rectifier, and a throttle switch connected at its input, providing a sinusoidal form of current pulses through the rectifier diodes and reducing, due to this, the size of the device for switching thyristors. When an inverter with a series resonant LC circuit is used for switching thyristors, additional diodes should be applied anti-parallel to the thyristors, which increases the cost of the converter. In the present invention, the role of additional oncoming diodes is performed by high power diodes, thereby simplifying the converter circuit and reducing its cost. The essence of the invention consists in switching on the switching LC circuit in parallel with the rectifier input.

The proposed Converter (see drawing) contains an inverter on the thyristors

TI - fi with an output transformer TP and

Mi-D rectifier, output

which included the filter capacitor SF,

and at the entrance is a choke filter bf.

The contour parameters bf-sf are chosen as

so that sinusoidal current pulses with a duration shorter than the duration of the inverter's operating noluperiod are passed through the Dg-D4 diodes by an amount exceeding the recovery time of the thyristor controllability. This provides a natural switching thyristor inverter load current converter.

To ensure the switching current of the transformer magnetizing and. current due to losses in the transformer, parallel to the rectifier input is included a switching resonant circuit, the period of operation of which corresponds to the working half-period of the inverter. Back half wave

the current of the LK-Cc chain, which has flowed through the rectifier diodes, transmits the excess energy to the load, being stored in the chain, ensuring the switching of the thyristors and. output voltage stability of the converter.

With increasing load resistance above the critical value

one

Rn

4Ск /

(where f is the operating frequency of the investor, PTOrp), the output voltage of the converter will increase dramatically. Therefore, in the case of a wide range of inverter load variation, the frequency of the thyristor control pulses of the inverter should decrease with increasing load resistance above a critical value. This can be done automatically when connected.

control pulse frequency adjustment devices to the output of the converter.

Subject invention

The DC / DC converter contains a thyristor inverter with a commutator, with its series resonant one. LC circuit, a rectifier connected at the output of the inverter transformer, and a smoothing filter consisting of a capacitor connected directly at the output of the rectifier, and a throttle switched on at the input of the rectifier, characterized in that, for the purpose of simplification, switching The chain is connected parallel to the rectifier input.