SU1431023A1 - D.c. to a.c. voltage converter - Google Patents

Abstract

The invention relates to a converter technique and can be used in conversion devices for converting a voltage of a primary source into a variable voltage of a controlled magnitude and frequency. The purpose of the invention is to simplify the converter. To this end, a DC / AC converter, containing a bridge inverter, each arm of which, as well as a power switch, included in its power supply circuit, is shunted by an inverse diode 11 and made in the form of a series-connected transistor for g

Description

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WITH

to

with

a plate chain 12 dp. of reduction of dynamic losses, and a thyristor 10, as well as a control unit, made, in the form of a series-connected master oscillator, a control voltage generating unit, one of the outputs of which is connected to the power key control unit, and the second - to the input of the amplifier-breakout unit, in which the output windings of the isolation transformer 15 are connected to the control circuits of the bridge inverter transistors, delay nodes are inserted, each of which is connected between the output winding a transformer and a thyristor control switch, the delay node being in the form of a matched delay line loaded on a key element made in the form of a transistor. The rotation is achieved by eliminating the isolation transformer, .1 Cp. f.p1, 5 Il.

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The invention relates to a converter technique and can be used in converter devices for converting a voltage of a primary source into a variable voltage of a controlled quantity and frequency,

The purpose of the invention is to simplify the structure.

Fig. 1 is a functional diagram of a DC / AC converter; 2 is a schematic diagram of the power arm of the bridge inverter J in FIG. 3 — an example of the implementation of the amplifier unit of the control unit of FIG. 4 — an example of the execution of the control unit by the power key j in FIG. 5 — time diagrams explaining the principle of formation of the control units thyristor and transistor voltage across the bridge inverter.

The converter contains a bridge inverter 15 in the power supply circuit; a pair of controllable power switch 2, a control unit 3 consisting of a master oscillator 4, a control voltage generation unit 5 a control unit of the power switch 6 and an amplifier-developing unit 7 are connected in pairs (FIG. 1) . A load of 8 is included in the diagonal of the bridge.

Each arm of the bridge IV of the Rotor 1 consists (figure 2) of a series-connected power transistor 9 and thyristor 10, shunted by a reverse diode 11 o The power transition of the transistor in the shoulder is bridged by a correction chain 12. The control input of the transistor 9 is connected via a resistor 13 to the output winding 14 of the expanding transistor 15 of the amplifying node 7, the control input of the thyristor 10 through the limiting resistor 16 and the node of the delay 17 is connected to the winding -14 of the transformer 15. The node of the delay 17

consists of a matched delay line 18, loaded on a key element, for example, a transistor 19, and a resistor 20. The protective circuit 12 consists of a capacitor 21,

diode 22 and resistor 23.

The master oscillator 8 can be performed but the circuit of the multivibrator.

The control voltage forming unit 5 can be performed according to

a pulse-width modulator circuit whose input and output are loaded on a trigger operating in the frequency division mode by two.

Reinforcingly developing knot

can be made according to the scheme of a push-pull power amplifier with a transformer output (FIG. 3),

The control unit of the power switch (Fig. 4) can be made according to the amplifier circuit with optoelectronic isolation.

The converter works as follows

This converter implements such an algorithm for switching the thyristor and the transistor of one of the shoulders of the bridge inverter, at which a triggering switch is initially fed to the transistor and, through Rem G, to the thyristor. The value of 2 is chosen from the condition of elimination of through currents in series-connected shoulders of the bridge inverter and usually depends on the power of the inverter, the type of transistors, and ranges from one to several Q microseconds. Simultaneously with the supply of a locking control pulse to the T1 anzistor and thyristor, the power switch connected in series with the bridge inverter is locked, thereby ensuring the formed thyristor blocking of the bridge inverter, as well as limiting the voltage across the protective circuit capacitor at level 3 -4 V, which 20 significantly reduces the magnitude of the dynamic losses on the transistor at the moment it is turned on, and therefore

increases the reliability of the converter .25

When the power key is subsequently turned on, the thyristor 10 has time to restore its locking properties, and

the transistor 9 maintains the voltage up to which the capacitor 21 of the protective circuit 12 is charged; i.e. to a value of 3–4 V. The fact that the voltage across the transistors of the bridge inverter is limited to a level of several volts allows refusing the amplifying and developing unit with a transformer output connected to the control circuit of the thyristors inverter, and to use for the thyristor control circuits the output voltage of the amplifying and developing unit connected to the control circuit of the bridge inverter .45

Fig. 3 shows a voltage diagram 24 on the output winding of the isolation transformer 15. A delay of 1 as of the switching on of the thyristor 10 is performed with CQ using the delay circuit 17. One of the possible technical implementations of the delay circuit with minimal instability of the delay time is given in technical solution. When a control voltage winding 14 with polarity plus appears at the base of the transistor, minus at the emitter, after a time equal to the delay line 18, a unlocking voltage appears at the base of transistor 19 and it opens. In this case, a current (diagram) 25 flows through the resistor 16 in the thyristor control circuit Yu and the thyristor opens,

 The invention makes it possible to significantly simplify the converter, since it excludes not only a number of active and passive elements from the control circuit, but also eliminates such a low-reliability and non-technological element as an isolation transformer of the amplifying and decoupling unit.

Claims (2)

1. DC-to-AC converter, containing a bridge inverter, each arm of which is made of serially connected power transistors backed up by a protective chain to reduce dynamic losses, and the thyristor, with each arm of the inverter and the power switch included in its power supply circuit, is bridged by reverse diodes, and the control inputs of each arm are connected to the outputs of the control-amplifying unit of the control unit through the output windings of the isolation transformer, node is connected to the first output of the control voltage generation node, the second output of which is connected to the control input of the latter through the control node with a power switch, characterized in that, in order to simplify nor, the nodes of the a-support, each of which is included. between the output winding of the isolation transformer and the thyristor control input. 2. The converter according to claim 1, differs in that the delay node is made in the form of a matched delay line loaded on a transistor key element. L.J U u ./WV WV / H ge 1-2 and frig1 P e-ff  + d Phi. fi.b