SU1117800A1 - Adjustable inverter - Google Patents

Abstract

A CONTROLLED INVERTER containing a transformer, the secondary winding of which is connected to the terminals for connecting the load, a choke connected between the first power supply bus and the middle output of the transformer primary winding, the extreme transformers of which through transistor switches are connected to the second power supply bus, characterized by that, in order to increase the RCC and simplify the circuit, two thyristors were inserted into it, connected to the bottom of the transformer primary windings and the first power supply bus.

Description

1 The invention relates to converter technology and can be used in the development of secondary power sources for converting DC voltage to AC. A variable inverter is known, which comprises a bridge power amplifier with transistors shunted by return diodes, with a pulse-width voltage regulation in a diagonal-alternating current to which the choke and the transformer G1 are connected. The disadvantage of this device is low efficiency, since the primary current of the transformer flows through two semiconductor elements to any step of the circuit operation. The closest to the technical essence of the invention is an adjustable inverter containing a transformer. The secondary winding of which is connected to the load, the choke connected between the first power supply bus and the middle output of the transformer primary winding, the extreme of which through transistor switches are connected to the second power supply bus C2J. The disadvantages of the known inverter are the complexity of the circuit due to the presence of a pulsed voltage regulator made using a smoothing 1, -C-0 filter and a transistor interrupter in the form of two transistors, which are shunted by reverse diodes connected between the ends of the primary winding of the transformer and the common point of connection of the diode and the filter capacitor, as well as the low SCR, caused by additional losses in the filter diode. The purpose of the invention is to increase efficiency and simplify the scheme. The goal is achieved by the fact that a regulated inverter containing a transformer, the secondary winding of which is connected to a load, a choke connected between the first power supply bus and the middle output of the transformer primary winding, the extreme leads of which are connected via a transistor switch to the second power supply bus, Two thyristors are inserted, connected between the ends of the transformer primary winding and the first power supply busbar. 0 2 FIG. 1 is a schematic diagram of an inverter in FIG. 2 time diagrams for his work. An adjustable inverter contains a transformer 1, the secondary winding 2 of which is connected to the load 3, a choke 4 connected between the first power supply bus 5 and the middle output of the primary winding 6 of the transformer 1, the extreme leads of which are connected to the second h bus 9 of the source nutrition Two thyristors 10 and 11 are connected between the extremes of the primary winding of the transformer 1 and the first bus 5 of the power supply. Adjustable inverter works as follows. A control device (not shown) generates control currents of transistor switches 7 and 8 and thyristors 10 and 11 (FIG. 2). Suppose that in the time interval (tj, -t-,) both thyristors 10 and 11 are closed, and transistor switch 7 is open. When this power source voltage across the choke 4 is applied to the lower half winding of the primary winding 6 of the transformer 1, the current in the choke 4 increases (Fig. 2). At time i, transistor switch 7 is closed and disconnected; thyristor 10. Current throttle 4 flows along the circuit: choke 4 - lower winding of the primary winding 6 of the transformer 1 - thyristor 10. In the interval (c-t) the inverter does not consume current from the power source, and the power stored in choke 4. The voltage on choke 4 changes its sign and the current in it begins to fall (Fig. 2, 0 4). In this case, since the direction and magnitude of the current in the primary winding 6 of transformer 1 are maintained, turning off transistor switch 7 and turning on thyristor 10 does not cause a dip in the output voltage of transformer 1 (Fig. 2). At time tj, the second thyristor 11 opens, the primary winding 6 of the transformer 1 and, therefore, the choke 4 is short-circuited. The output voltage of the inverter is zero, and the current of the drossel 4 slowly decreases, it flows simultaneously on both thyristors 10 and 11. In this case, since

3t

the voltage on the inductor 4 is zero, the magnitude of the current of the throttles 4 at time t (Fig. 2) is slightly different from the value of this current at time t. At time t, both transistor switches 7 and 8 open. This leads to a change in the sign of the voltage on thyristors 10 and 11 and the closure of the latter. In the interval (tj-t;), the voltage on the primary winding 6 of the transformer G remains as before zero (FIG. 2), and the entire supply voltage is applied to the choke 4. The duration of this time interval must be equal to the thyristors off time 10 and 11. After the time t, only the transistor switch 8 is turned on, the voltage of the power source through the choke 4 is applied to the upper half winding of the primary winding 6 of the transformer 1, the output voltage

04

the inverter changes sign, and the current of drossel 4 continues to increase. At the moment of time -ty the transistor switch 8 is closed, you open the thyristor 11, the voltage at the output of the inverter retains its sign and its value.

At the moment of time, the thyristor 10 is additionally opened, the voltage across the windings of the transformer 1

drops to zero, and then the switching processes in the circuit are repeated.

The output voltage is controlled by varying the ratio of the lengths of the time intervals (), (t4-t5.) And (t, -tp, (t5-te).

The proposed device has a significantly higher efficiency than the known, due to the fact that the current

Drotsel and power supply sources never flow through more than one semiconductor device, which is a consequence of the simplification of the circuit.

Claims (1)

A REGULATED INVERTER containing a transformer, the secondary winding of which is connected to the terminals for connecting the load, a choke connected between the first bus of the power source and the middle terminal of the primary winding of the transformer, the extreme terminals of which are connected to the second bus of the power source, characterized in that that, in order to increase efficiency and simplify the circuit, two thyristors are inserted into it, connected between the extreme terminals of the primary winding of the transformer and the first bus of the power source. SU „, 1117800