SU511658A1 - Stand alone voltage inverter - Google Patents

Description

one

The known circuits of autonomous voltage inverters with two-stage switching and devices for increasing the blocking voltage on the thyristors have either insufficiently high energy indicators or complex circuits that reduce the reliability of switching,

The purpose of the invention is improving the reliability of switching while maintaining the basic X parameters of the switching circuit.

This is achieved by the fact that a parallel connection is established in the circuit of the reverse current diodes of the inverter through. separation diodes connected capacitors and secondary windings of an additional transformer, the primary winding of which is included in the discharge capacitor discharge circuit

On FKG, 1, a schematic diagram of an autonomous voltage inverter is shown (the first option); fig 2 is the same (second option); in fig. 3 - diagrams of the inverter.

On the circuits: 1-8 - commuting thyristors; 9-14 - main inverter thyristors; 15-20 - rim current diodes;

21 - switching capacitor; 22, 23 - commuting | Drossel; 24, 25 additional chokes; 26, 27 — additional capacitors of the bias circuit; J 28 — transformer; 29-32 - separator: diodes.

Suppose (see Fig. 1) that the thyristors 9, 10, and 14 are turned on, and the switching capacitor 21 is charged with the polarity indicated in this figure.

To turn off the main thyristor 9, switching thyristors 1 and 4 are switched on. Switching capacitor 21 is charged across the circuit: Source Up — thyristor 1 — choke 22 — capacitor 21 — thyristor 4 — load — thyristor 14, source J-. The shape of the current,) flowing € -O

Go through the Conde; Juator 21, shown

Claims (1)

in fig, h. At time I, the current of the thyristor 9 drops to kul, and the discharge current of the capacitor begins to flow through the diode 15 (cm, 36) and a chain of other; x villages 24 and capacitor 26, the shape of the voltage on the capacitor 26 and, correspondingly the switchable thyristor 9 is shown in FIG. Sv, d. On the iy-t interval, the reverse voltage across the thyristor 9 is determined by the voltage of the capacitor 26, which creates a negative gate voltage when the discharge current of the switching capacitor flows through it. Fig. 2 shows an inverter circuit in which capacitors and transformer secondary windings, the primary winding of which is connected to the discharge circuit of the switching capacitor, are connected in parallel to the reverse diode circuit through separate isolators to obtain a higher negative voltage value. The operation of the circuit is similar to that described. The only difference is that at the first moment of Jkaupacation (t.-t) the negative voltage of the thyristor 9 is determined by the voltage on the choke 24, since the capacitor 26 is separated from the discharge of the diode 29. At the same time the charge occurs: the capacitor 126 by the current of the secondary winding of the transformer 28. At time i at which Uo. and and. the voltage 24 2 is compared, the diode 29 is opened, and the voltage of the thyristor 9 is determined by the voltage of the capacitor 26. At the time point / process THpuciofja turns off. The form of the blocking voltage on the thyristic 9 is shown in FIG. H. With an appropriate calculation of the parameters of additional elements, it is possible to provide the necessary amount of blocking voltage on the thyristor being turned off. In order to accelerate the process of dissipating the energy of the additional chokes 24 and 25, after the termination of the thyristor switching process, additional resistors may be connected in series with the capacitors 26, 27. Claims of the invention A stand-alone voltage inverter containing a three-phase main thyristor bridge, a three-phase circulating current diode bridge connected to the power supply terminals via chokes, a switching node containing a switching chain of series-connected switching capacitors and throttles connected via switching thyristors to the source power supply and main thyristors, characterized in that, in order to increase the reliability of switching, parallel to the throttle in the circuit of reverse current diodes through divide The diodes are connected to capacitors and secondary windings, an additional transformer, the primary winding of which is included in the discharge capacitor discharge circuit. ISi +  I "N “To niTr llr ir  t: nW f “V h f -V“ O N "M "M .yw. Jq "M W. / wx.