SU381142A1 - ALL-UNION I - Google Patents

Description

one

The invention relates to a converter technique.

Known bridge inverters operating at high voltage supply, containing power key elements in the form of thyristors and chains of series-connected transistors.

In the proposed inverter, the chains of transistors are included in the two arms of the bridge, connected to one of the supply terminals of the inverter, and the thyristors - in the other two arms. This reduces the power loss of control and increases the reliability of the inverter.

FIG. 1 shows the scheme of the proposed inverter; in fig. 2 - the form of its output voltage; in fig. 3 - possible variation of the proposed inverter circuit.

The inverter connected to the power source 1 contains a bridge, the shoulders of which are formed by thyristors 2, 3 and chains of series-connected transistors 4 to 5.

At the output of the inverter active load is enabled 6.

In the time interval when the output voltage of the master oscillator 7 is zero (O- / 1 in Fig. 2), the thyristors 2, 5 and transistor chains 4, 5 are locked. At time ti, the generator receives a control pulse to the thyristor 2 and a constant voltage to

transistor chain 5, which leads to their inclusion. From this moment on, the current from the source / begins to flow through the load 6, as a result of which a voltage appears on it, the polarity of which is indicated in FIG. 1. At time / 2, the transistor circuit 5 closes, after which until time / 3 the thyristor 2 and the load 6 are maintained in the disconnected state. The duration of this interval

0 time must not be less than the time off thyristors 2, 3.

At time 3, the thyristor 3 and the transistor chain 4 are opened, as a result of which voltage is again applied to the load 6

5 source /, but opposite polarity (in Fig. 1 is indicated in brackets). This polarity on the load is maintained until time U, after which transistor circuit 4 and thyristor 3 are disconnected, and voltage on the load

0 becomes zero.

From the moment t, the processes described are repeated.

The output voltage of the proposed inverter can be adjusted. For this, the ratio between the time intervals O- / i (2-4) and () is varied. If the resistance of the divider shunting the transistors of the chains 4 and 5 is small enough (the divider is not shown in Fig. 1), it is possible failure of the inversion at low currents disconnecting thyristors 2 and 5.

An inverter, whose circuit is shown in FIG. 3, has no marked drawback.

This scheme differs from that shown in FIG. 1 by the fact that diodes S and I are connected in series with thyristors 2 to 3, and a encoder 10 is connected between the common points of the diodes and thyristors.

In parallel to the capacitor diodes / and 2 are connected, between the common point of which and the common point of the thyristors resistor 13 is connected.

In the diagram in FIG. 3 thyristors 2 and 5 are turned on at the moment 1-2 or t, and the capacitor 10, discharging in the interval O-1 or tz-t through diode 11 (12), resistor 13 and thyristor 3 (2), contributes to reliable disconnection of the thyristor 2 (5).

Subject invention

Claims (2)

1. A bridge inverter operating on a resistive load containing power key elements in the form of thyristors and chains of series-connected transistors, characterized in that, in order to increase the efficiency and reliability, chains of transistors are included in the two arms of the bridge, connected to one of the supply terminals of the inverter, and the thyristors - in the other two arms. 2. The inverter according to claim 1, characterized in that, in order to increase the reliability of the switching of the thyristors, sequentially with each of them 5 includes separating diodes, and a capacitor is connected between the common points of the diodes and the thyristors, in parallel with which is connected a chain of opposite-connected additional diodes, and 0 between their common point and common point of thyristors resistor is entered.