SU1534673A1 - Device for controlling ac thyristor contactor - Google Patents

Abstract

This invention relates to electrical engineering, in particular, to control devices for thyristor AC contactors. The aim of the invention is to reduce the cost and increase the reliability of the device. The shaper 4 rectangular pulses are connected to the R- and S-inputs of the RST flip-flop 5 and through the shapers of short pulses 7 to the element 2 OR 8. The output of SIFU 9 is connected to the T-input of the flip-flop 5, the outputs of which are connected to the control through the shapers 6 the electrodes of the contactor 1. The power in the load 2 changes from zero to maximum when the control voltage SIFU changes from zero to the maximum value of the saw voltage SIFU. 2 Il.

Description

The invention relates to electrical engineering, in particular, to devices for the eradication of thyristor contactors with variable

The aim of the invention is to reduce the cost and increase the reliability of the device.

Figure 1 shows the functional diagram of the device; on - time charts that explain the principle of operation

The device contains a thyristor contactor 1 connected in series with a load 2, a separator transformer 3, the primary winding of which is connected in parallel with the thyristor contactor 1, the shape of a world-4 rectangular pulse, the inputs of which are connected to the secondary-phase output terminals dividing transformer transformer ST 3, RST-trigger 5, direct and inverter inputs of which are connected respectively to the antiphase outputs of the former 4 rectangular pulses, two formers 6 control pulses connected with By the outputs of trigger 5, the output of the first and second shaper 6 control pulses are connected respectively to the control circuit of the first and second thyristor of the contactor 1, the shaper 7 short pulses, whose inputs are connected to the antiphase outputs of the shaper 4 rectangular pulses, element 2 OR 8, the input of which is connected to the output of short pulse size drivers 7, the pulse phase control unit 9, the input of which is connected to the output of the OR element 8, and the output is connected to the clocked T input of the RST trigger 5, clamps 10 and 11 I feed its voltage "

Fig. 2 shows the power supply voltage (at terminals 10 and 11) (a), the voltage on the primary winding of the isolation transformer 3 (6), the voltage on the antiphase outputs of the former 4 rectangular pulses (c and d), for example On the outputs of the shapers 7 short pulses (que), the voltage at the output of the element OR 8 (g), the voltage on the elements of the pulsed-phase control unit 9, the sawtooth Un and the control Uu. (e), the voltage at the output of the phase control unit 9 (and), the voltage across the load 2 (k).

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The device works as follows

When the control voltage and a smaller sawtooth voltage Un (fig. 2z) in the time interval C – t, C – t4, and so on, the output of the phase control unit 9 and, therefore, the clocked input of the RST flip-flop 5 is present logical Thyristors of contactor 1 are closed (fig.2b), the voltage on load 2 is zero (fig 2k). At the same time, rectangular pulses of duration t4 and t0 are formed at the antiphase outputs of the former 4 rectangular pulses. (fig „2b, d), at the outputs of the formers 7 - narrow pulses (, е) at the moments of time corresponding to the natural passage through zero of the load current. At the output of the element OR 8, narrow pulses are formed every 180 ° (), with the help of which the sawtooth voltage Urt is formed (Fig. 2z) o At the moment of equality of the control voltage Uu and sawtooth U (times t, t4, etc. a) at the output of the phase control unit 9, a logical 1 is formed (Fig. 2i) which is fed to the clocked input of the trigger 5. At the same time, the trigger switches and. at its output (direct or inverse) HS, therefore, at the output of the driver of control pulses, a pulse is generated that unlocks the corresponding thyristor, a voltage appears on the load (Fig. 2k). i

With equal control voltages, Uu. and sawtooth (time interval t -, fig.2z) at the output of phase control unit 9 pulses are formed (fig.2i) at the moments of natural crossing of load current through zero (t7, tg and tod). In this case, the control angle oi 0 and the total supply voltage is applied to the load (Fig. 2k, interval t7-). At U, the control angle is f / 180 °, the thyristors do not open, and the voltage across the load is zero. Thus, the device allows, when the control voltage changes from zero to maximum (), it is possible to regulate the voltage (power) on the load

Use of shapers for short puls and the element OR joint51

but with a phase control unit, the voltage transformer and the second square wave driver are eliminated, which reduces the cost and increases the reliability of the device.

Claims (1)

Invention Formula A device for controlling a thyristor AC contactor containing an isolation transformer, the primary winding of which is connected in parallel to the thyristors of the contactor, and the secondary transformer to the input of the rectangular pulse former, the antiphase outputs of the rectangular pulse former are connected to the R and S inputs of the RST trigger, right my 346736 and the inverse outputs of which are connected via control pulse drivers to the control electrodes of the contactor thyristors and a pulse-phase control unit whose output is connected to the T input of an RST flip-flop, which, in terms of reducing the cost and improving reliability, it is equipped with two short pulse shapers and a 2IL element, with the short pulse shaper inputs of the owls connected to the antiphase outputs of the square pulse shaper, the outputs to the inputs of the OR element 2, the output of which The key to sinhroniruyuschemu Valid pulse unit but-phase control. M H "I n / .kfc f &