SU765993A1 - Alternating pulse shaper - Google Patents

Description

The invention relates to magnetic semiconductor automation devices and can be used in automatic control devices on semiconductor elements. A device containing a source of constant voltage and four transistors connected via a bridge circuit with a clamping transformer l is known. To control semiconductor elements operating in the key mode, a signal is required only for a time equal to the time of locking or unlocking. The remaining time after switching the semiconductor element to the next switching of the power of the control device is not used. The disadvantage of this device is that it does not provide a pause after rectangular control pulses of alternating polarity, which is necessary when controlling semiconductor elements. The closest in its essence to the invention is a shaper of short, direct pulsed alternating polarity comprising an alternating voltage source, a current limiter connected in series with a saturable transformer, two counter-parallel circuits consisting of a series-connected triode and diode , the base-emitter junctions of the triodes are connected to the windings of the saturating transformer, while the base of one triode is connected to the beginning, and the base of the other - to the end of the corresponding windings 2. The main drawbacks of the device. is lack of stability and reliability. In addition, it consumes power from a source of temporary voltage, which it is desirable to reduce. The purpose of the invention is to increase stability and reliability and at the same time reduce the power consumption of a control alternating voltage. This is achieved by the fact that in the alternating pulse shaper containing a current limiter connected in series with a saturating transformer, parallel to the primary winding of which the backfire suppression circuits connected to the secondary windings of the transient transformer are connected, and the transient transformer is supplied with two additional windings, the midpoint of the DC voltage source is connected to the end of the primary winding of the terminating transformer, and Its beginning is to the midpoint of the current limiter, made on two transistors by half-bridge circuit and connected to the source of direct voltage, in the base-emitter circuits of the transistors the limiter is connected in parallel and according to each other the secondary winding of the saturable transformer with the corresponding base resistor and additional the winding of the transition transformer with a series-connected base capacitor.

The drawing shows the principle electrical diagram of the alternating pulse shaper.

The former contains sources of alternating and direct (with a midpoint) voltage (shown in the drawing), a current limiter 1 connected in series with a saturating transformer 2. The current limiter is made according to a half bridge circuit and contains transistors 3 and 4. The base of transistor 3 is through the base resistor 5 is connected to the end of the winding b, saturating transformer 2 and through the base capacitor 7 - to the end of the additional winding 8 of the transition transformer 9, the base of the transistor 4 through the base resistor 10 is connected to the beginning of the circuit 11 of the saturating transformer 2 and through the base capacitor 12 - To the top of the additional winding 13 of the transition transformer 9 The primary winding 14 of the transformer 2 is connected to the common point of transistors 3 and 4 and its end to the midpoint 15 of a constant voltage source.

Parallel to the primary winding 14 of the transformer 2, backfill suppression circuits 16 are included, comprising two opposite-parallel-connected circuits. The first circuit consists of a series-connected transistor 17 and a diode 18, the base of the transistor 17 is connected via a resistor 19 to the end of the winding 20 of the transformer 9. The second circuit consists of a series-connected transistor 21 and a diode 22, the base of the transistor 21 is connected through the resistor 23 to the beginning of the winding 24 transformers 9.

The shaper works as follows.

If a positive half-wave of an input alternating voltage is applied to terminal 25, then under the action of current in the winding 8, the transistor 3 opens and the primary winding 14 of the saturating transformer 2 applies a constant voltage equal to half the source voltage {between the positive terminal and the midpoint) . The voltage on the base winding b keeps .. the transistor 3 in the open state. A positive impulse is transformed to the output of the former.

After a period of time, transformer 2 begins to enter, causing a regenerative process. The current in the winding b increases sharply to a value determined by the base current of the transistor.

The voltage on the winding b drops, as a result of the regenerative process, the transistor 3 is locked, breaking the constant voltage circuit.

The transistor 4 of this entire half-cycle of the input AC voltage remains locked.

The power consumption of the variable voltage source by the shaper is very small, since now only the base transistors of the transformer are powered from it. The reaction in the form of a voltage drop at the moments of the formation of the back edge of pulses is absent.

When changing the polarity of the input AC voltage, i.e. in the next half-period, the device operates in the same way, with the difference that transistor 4 is opened, and a negative polarity pulse is transformed to the output.

Connected in parallel to the primary winding 14 of the backfire elimination circuit shunt the self-induction EMF, each in its half-period, so that backflushing during the formation of the trailing edges does not form.

Instead of a mid-voltage constant-voltage source, two equal voltage sources connected in series can be used.

The use of the proposed shaper short rectangular character pulses compared to existing ones has the following advantages:

The stability and reliability of its operation increases without reducing the characteristics of the parameters of the output pulses, since there is no voltage distortion in the power supply circuit including the emitter-collector junction of transistors, and the constant-current circuit is more stable;

there is no response from the alternating voltage source to the operation of the imager, the power consumption from it is reduced, since from it only small-sized basic transistor control circuits are powered, which is especially important for multichannel pulse-width regulators and a number of other devices.

Claims (2)

1. An alternating pulse feedformer containing a current limiter connected in series with a saturable transformer, parallel to the primary winding of which the backflung suppression circuits connected to the secondary windings of the transient transformer are connected, and a constant voltage source, characterized in that, in order to increase the stability and reliability of its operation, as well as to reduce the power consumption of the control alternating voltage, the transition transformer is equipped with two additional windings, the midpoint of the constant voltage source is connected to the end of the primary voltage winding saturating transformer, and its beginning - to the midpoint of the current limiter. 2. The feedformer of claim 1, which is different. that limiter current is made on two transistors on a half-bridge circuit and connected to a constant voltage source, with the current limiter in the BaEo-emitter circuit of the transistors being connected parallel to each other according to the secondary winding of the saturating trans1) Ormator with a corresponding base resistor and an additional winding of the transition transformer with a series-connected base a capacitor. Sources of information taken into account in the examination 1. Romash E.M. Transistor converters in electronic equipment power supplies, M., nerg | 1975, p. 6-8. 2. Authors certificate of the USSR 488331, cl. H 03 K 5/01, 1974. / f