SU1297199A1 - Transistor inverter - Google Patents

Abstract

The invention relates to converter equipment and can be used in secondary power supply sources. The purpose of the invention is to reduce the weight and size by simplifying. The inverter contains two half bridges on transistors 1-4, an output transformer 6, an output circuit of 12-yyyyyyyyyyyyyyyyyyyyyyyyyy, 8, choke 12, additional circuits of 13 and 14, made on diodes 15 and 17 and a shunt capacitor 16. Introduction Connecting them reduces the number of auxiliary chokes and simplifies the device. Due to the additional circuit 13, the increase in the voltage on the capacitor 16, and, consequently, the voltages on the transistors 2 and 3, occurs with a delay in relation to the current decay through these transistors. This provides a reduction in dynamic losses in transistors. At the moment of discharge of the capacitor, which occurs according to the cosine-like law, the current in the auxiliary inductor is sinusoidal and after reaching zero value is transferred to the load. 2 Il. SL C --CH with CO with

Description

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The invention relates to converter equipment and can be used in secondary power supply sources.

The aim of the invention is to reduce jass and size by simplifying the circuit.

Figure 1 presents the scheme of the proposed transistor inverter; Fig. 2 shows current and voltage diagrams in the inverter.

The transistor inverter (Fig. 1) contains two half bridges, in whose arms transistors 1 to 4 are connected. In the bridge diagonal, the primary winding 5 of the output transformer 6 is connected, the secondary winding 7 of which is connected to the output circuit 8 of the inverter containing rectifier 9, load 10 co. smoothing capacitor

11. Consequently, the main choke is connected to the inverter power supply circuit.

12. Additional chains 13 and 14 each contain three branches connected in a star. In this case, the first branch of each

of circuits 13 and 14 contains a charge diode 15, the second branch contains a shunt capacitor 16 and a third branch of the discharge diode 17. Each additional circuit has an external output of the first branch connected to the common point of the transistors of the corresponding half-bridge, the external link of the second branch half bridges, and between the external leads of the third branches of the additional circuits 13 and 14 the additional winding 18 of the output transformer 6 is turned on. The auxiliary choke 19 is connected between the tap from the middle point of the additional winding and 18 output transformer 6 and one of the conclusions of the main throttle.

One of the options for connecting the secondary throttle 19 is shown in Fig. 1 as a dashed line.

In the current and voltage diagrams shown in FIG. 2, the indices correspond to circuit elements.

The inverter works as follows.

Current droplets 12 (Fig.2) flows alternately through transistors 1, 4 and 2, 3. We consider the operation of the device on the example of a half-bridge containing transistors 1 and 2. In the initial state up to to open the trans5

one

0

, 50

five

Q

five

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Sistors 2 and 3, Capacitor 16 bits.

At the moment to, the polarity of the control signal on the bases of the transistors changes. In the subsequent interval to and t, all transistors are turned on due to resorption in previously opened transistor drives. For this interval, the increase in current of droplets of 12 1dr under the action of supply voltage U ,, t decreases to zero current in the inductance of transformer under action of stress on the load and,.

At time t, transistors 2 and 3 are closed and transistors 1 and 4 open, skipping the current i,. In the next interval t, and t, the current of the drossel 12 1dr flows through the open transistor 1, the charge diode 15, the capacitor 16, and charges it. The increase in the voltage U. on the capacitor 16, and hence the voltages and "and U, on transistors 2 and 3, occurs with a delay in relation to the current decay ij,, i through these transistors. This provides a favorable turn-off path for transistors 2 and 3 and a reduction in dynamic losses in these transistors. This state cxeMiii continues until time tj ,, when the voltage on the capacitor 16 (on the winding 5 of the transformer 6) reaches the voltage on the load, reduced to the primary winding and ,.

At time t, rectifier diodes 9 are opened and a current of 1 rp starts to grow (in the primary winding circuit 5 of the output transformer 6. After this time, the current of throttles 12 is redistributed between the capacitor 16 and the primary winding 5 of the transformer 6. At time tj, the charge ends the capacitor 16, the diode 15 is closed and the voltage on the capacitor 16 is as high as and equal to

 - with,

On the following intervals t, t ,, and t, tj., I.e. until the moment of time t., when the next switching of transistors in the shoulders of the bridge occurs, a partial discharge of the capacitor 16 occurs, which has no fundamental character. This discharge occurs along the circuit of the discharge diode 17, as well as through the conductivity of the leakage of the diode 15.

At intervals t, and tg, the energy stored in the shunt capacitor 16 is recuperated into the load. Starting from the moment of time t ;, transistors 2 and 3 are open, and transistors 1 and 4 are closed. The voltage UTO, on the primary winding 5 and on the additional winding 18 of the output transformer 6, has the polarity indicated in Fig. 1 without brackets. The capacitor 16 is connected through the discharge diode 17 and the auxiliary choke 19 and the back-EMF and |, - 1/2 DCP (where is the voltage

on the additional winding 18 of the transformer 6). The main discharge of the capacitor 16 occurs. This discharge is oscillatory, the voltage on the capacitor 16 drops according to a cone-shaped law, and the discharge current (recovery) 1 .. "flowing through

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auxiliary choke 19, has a sinusoidal shape. After the voltage on the capacitor 16 reaches zero at time t, the residual energy in the auxiliary choke 19 is transferred to the load by current 1

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flowing through the chain:

transistor 3 - winding 5 a transformer inverter containing 20 half bridges in whose arms transistors are included, an output transformer with an additional winding, the primary winding of which is connected to the common connection points of the half bridge transistors, the main throttle whose first output is connected to the positive one power supply and the second to one common connection point of the half-bridges, and two dopolmators 6 — charge diode 15 — discharge circuits to form a source diode 17 — half of the transformer winding 18 and 6,

Additional circuit 14 provides a rise-voltage on transistors 1 and 4. The processes in this circuit are similar to those considered, In an inverter, when an auxiliary choke | 19 is connected between a tap from the additional winding 18 of the transformer 6 p input terminal, the fundamental difference in the processes compared to with reviewed no. In this case, the discharge of shunt capacitors occurs in the power source of the inverter.

For these schemes, the number of turns of the windings 5 and 18 of the transformer 6 is advisable to choose equal. Wherein

; -1/2 „

1/2 and;,. I and ,.

UH - 1/2 and;

(where iS is the voltage on the shunt capacitors by the time the discharge starts), In this

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In this case, a full discharge of shunt capacitors is observed. The duration of the energy shunt capacitor energy recovery intervals is determined by

5 parameters of capacitors and auxiliary choke.

Thus, in the proposed inverter, the number of auxiliary chokes is reduced, i.e. The device layout is simplified, with the mass and dimensions of one auxiliary drossel reduced relative to the known device with two auxiliary throttles of about 1.3.

J5 times.

Claims (1)

Invention Formula A transistor inverter containing two half bridges in whose arms transistors are connected, an output transformer with an additional winding, the primary winding of which is connected to the common connection points of the half bridge transistors, the main throttle whose first output is connected to the positive power source and the second - to one common point of connection of half-bridges, and two additional ones tight chains to form trao0 the switching paths of the transistors, consisting of three star-connected branches, the first of which contains a charge diode and is connected 5 by an external output to the common connection point of the transistors of the corresponding half-bridge, the second branch contains a capacitor capacitor and is connected by an external output to another common connection point of the half-bridge, the third branch contains a discharge diode, and an auxiliary choke, characterized in that in order to reduce the weight and size by simplifying the circuit, the additional winding of the output transformer is provided with a tap from the middle point and connected between the external leads of the third branches of the additional circuits, and the secondary choke is turned on chen between the tap from the middle point of the additional winding of the output transformer and one of the output of the main throttle.