RU1838869C - Independent current inverter - Google Patents

Abstract

Usage: in the conversion technique. SUMMARY OF THE INVENTION: The device comprises a bridge on thyristors with cut-off diodes and switching capacitors. Reverse diodes are connected to the zero point of the load circuit. The presence of two reverse diodes provides high stability of the inverter in dynamic modes. 1 ill.

Description

The invention relates to electrical engineering, in particular to electric current converters, and can be used to convert direct current to alternating current in a controlled asynchronous and synchronous electric drive, as well as in power plants.

The aim of the invention is to increase the switching stability of thyristors by qualitatively increasing the level of switching voltage on the thyristors while increasing the reactive power of a stand-alone current inverter, if it is operated on a dynamic inductive load.

Expected Benefit:

- the switching stability of tm ristoroa increases over a wide range of loads, 1

- the reactive energy of the inductive load is compensated, i.e. the inverter reactivity increases;

- compensated reactive. energy is used in the active load circuit, with its preliminary deposition in switching capacitors;

- the non-sinusoidality of the output voltage curve is reduced, which reduces losses in the coupled electrical machines.

To achieve this goal, in the well-known stand-alone current inverter containing a three-phase thyristor bridge with cut-off diodes and switching capacitors connected to the connection points of the thyristors and diodes in the star or delta circuit, connected by the DC terminals through the inductor to the terminals of the DC source, and the terminals alternating current - to a three-phase load circuit directly or through a transformer, two series-connected reverse diodes connected in parallel to the bridge and connected | connected to a common point with a zero terminal of the load circuit or a zero terminal of the primary winding of the transformer. Reactive load currents in the form of pulses following the pulses of the phase currents, closed through the return diodes, flow through the switching capacitors, where the pulse potentials are summed, as a result of which the switching potential is accumulated, which exceeds the value of the interphase voltage, i.e. UK Uu, which is a guarantee of stable thyristor switching.

Distinctive features: the use of diode compensation with deposited

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eat energy in switching capacitors; an increase in the switching voltage (common sign) due to the accumulation of energy of the switching capacitors and, as a result, a qualitative increase in the stability of switching thyristors.

Hi) drawing © shows an electrical circuit diagram of an autonomous current inverter,

.Autonomous icertorque connected by DC leads through a throttle to the terminals of the DC source, and by the AC terminals to the three-phase load circuit, contains three-phase washes from thyristors 1 ... 6 with cut-offs 7 ... 12, switching capacitors 13,. Ш of the anode m 16 ... 18 of the cathode group, connected by a star circuit, compensating the inverse diodes 19 and 20, connected® parallel to the bridge and connected by a common point with the zero terminal N of the load circuit ZH.

Claims (1)

The claims A self-contained current inverter containing a three-phase thyristor bridge with cut-off diodes and switching capacitors connected to the connection points of the thyristors and diodes in the star or delta circuit, connected to the DC terminals through the inductor to the terminals of the direct current source, and the terminals of the alternating current to the circuit of the three-phase load directly or through a transformer, characterized in that, in order to increase the reactive power and increase the stability of thyristor switching, introduced two series-connected reverse diodes connected parallel to the bridge AND connected by a common point with zero the output circuit of the load or the zero output of the primary winding of the transformer.