SU1101983A1 - Versions of device for adjusting thyristors connected in parallel opposing - Google Patents

Abstract

1. A device for controlling back-connected thyristors comprising a synchronization unit with the network, an R5 trigger and driver of control pulses, characterized in that, for the purpose of simplification, it is equipped with three amplifiers-formers, a differentiating chain and elements 2I and 2W, the inputs of the first and second amplifiers-formers are connected to the unit of the synchronization unit, the output of the first amplifier-former is to the first input of element 2I, the second input of which is before. assigned to connect to the source of the control signal, and the output is connected to the first input of the element 2W and the input of the RJ flip-flop, the output of the second amplifier-former is connected to the input R {-trigger, the inverse output through the differentiating circuit and the third amplifier forming the connection with the second the input of the element 2SHSCH, and the output of the element 2IL is connected to the input of the rotator for the control pulses. 2. A device for controlling anti-parallel thyristors, comprising a synchronization unit with the network and a driver for controlling pulses, characterized in that, for the sake of simplicity, it is equipped with a shaping amplifier, a 2I element and a single vibrator, and the driver for controlling pulses is executed in the form decelerated blocking generator, the amplifier maker input is connected to the output of the synchronization unit, its output is connected to the first input of element 2I, the second input of which is intended to be connected to the source control signal, and the output is connected to input 00 00 of the one-shot, the output of the one-shot is connected to the input of the driver of control pulses.

Description

The invention relates to electrical engineering, in particular to converter equipment, and can be used to control thyristors intended for switching AC circuits. Counter-parallel connected thyristors are used as power switches in the power supply of electrical transformers. To improve the reliability of such keys by eliminating current surges in transients when transformers are turned on (due to the residual magnetization of the ferromagnetic transformer cores), thyristor control systems are used to ensure the elimination of current surges by including the thyristors in the corresponding half-periods of the mains voltage. The elimination of current surges is achieved through the initial reversal of the transformer core. A device is known that contains a pulse shaper used to control thyristors and a magnetic memory unit that stores the residual magnetic flux in the core and turns on the thyristors in those half-periods of the mains voltage at which the initial reversal of the transformer core is reached. The drawbacks of the device are design complexity and lack of reliability. The closest in technical essence to the invention is a device for controlling counter-parallel-connected thyristors containing a synchronization unit with a set. The RS trigger and the C 2 3 control pulse shaper. A disadvantage of the known devices is its complexity, since for implementing this principle it also contains a thyristor current sensor, a magnetic memory unit, a threshold element, and a series of logic elements. The purpose of the invention is to simplify the device. To achieve this goal, according to the first variant, a device for controlling back-parallel thyristors, containing a synchronization unit with a network, a RiS trigger and a driver for controlling pulses, is equipped with three amplifiers, a differentiating chain and elements 2I and 2IL, and the inputs of the first and second the driver amplifiers are connected to the output of the synchronization unit, the output of the first amplifier driver is to the first input of element 2I, the second input of which is intended to be connected to the source control signal, and the output is connected to the first input of the 2IL element and the Trigger input, the output of the second amplifier of the driver is connected to the input of the R5 flip-flop, the inverse output of which is connected to the second input amplifier through the differentiating chain and the third driver of the driver 2IinH connected to the input of the driver control pulses. In addition, according to the second option. The device containing the synchronization unit with the network and the driver of control pulses is equipped with an amplifier driver, element 2I, and a single vibrator, the driver of the control pulses is designed as a braked blocking generator, the amplifier driver is connected to the output of the synchronizer unit, its output is the first input of the element 2И, the second input of which is intended to be connected to the source of the control signal, and the output is connected to the input of the one-shot, the output of the one-shot is connected to the input ate control pulses. FIG. 1 Shows the functional diagram of the device, the first option; 2 shows diagrams explaining the operation of the device; on fig.Z - the device, the second option. The device contains a synchronization unit with a network formed by a half-wave rectifier 1, amplitude discriminator 2 and differentiating circuit 3, first and second amplifiers 4 and 5, logic element 2I 6, RS-trigger 7, differentiating circuit 8, third amplifier 9 and logic element 2IL 10. The control of the thyristors is carried out by the driver 11 of the control pulses, the outputs of which are connected to the control electrodes of the thyristors 12 connected to the circuits

transformer 13 power supply. A clock voltage and a control signal are supplied to the device inputs to turn on the device.

The principle of operation of the device is that, regardless of the start and end of the control signal, with respect to the network voltage, the turn-on and turn-off phase of the device is opposite and set in advance, i.e. regardless of the moment of the beginning and end of the control signal, the thyristor is switched on in the positive half period when it is received, and the negative half period is turned off.

Consider the operation of the device (Fig. 1) according to the voltage diagram (Fig. 2). The half-wave rectifier 1 extracts from the synchronization voltage (diagram 14) positive half-periods (diagram 15), which are fed to the input of the amplitude discriminator 2. The output voltage of the discriminator 2 is a sequence of square impulses coinciding with the edges of zero-crossing network times wives (figure 16). From the leading and trailing edges of the pulses of the diverting circuit 3, opposite polarity pulses are formed (diagram 17) Positive polarity pulses are fed to the input of the first amplifier of the shaping device 4, which amplifies them (diagram 18), the second amplifier of the negative voltage 5 converts to positive pulses of negative polarity (diagram 19) From the output of amplifier 4, the pulses arrive at the first input of element 2I 6. If there is no signal to turn on the device, there are no pulses at the output of element 2I, the RS flip-flop 7 is in the zero state there are no pulses at the input of the control pulse generator 11. When the control signal is applied (diagram 20), pulses appear at the beginning of the positive half-cycles at the output of element 2I (diagram 21), which trigger trigger 7 and simultaneously through element 2IL start the control pulse shaper 11 and generating a short pulse to unlock the corresponding thyristor Trigger 7, translated as described

impulse to the unit state (diagram 22), remains in this state until the end of the half-period and the arrival at its input of the pulses I1 from the output of the amplifier-former 5 (diagram 19). The output of trigger 7 is removed from its inverse output (Figure 23). The differentiating circuit 8 forms from the output signal of the trigger a sequence of opposite-polarity pulses coinciding with the front 1 '1 with the moments of the transition of the mains voltage across zero (diagram 24). The third shaping amplifier 9 amplifies positive pulses at the output of the differentiating circuit 8, which coincide with the moment of the beginning of the negative half-period (diagram 25) Thus, regardless of the moment of supplying the control signal to this signal, after it is fed to the first input of the element 2Ш1И, pulses coincide with the beginning of the positive half periods and the second input are pulses that coincide with the onset of the negative half period, regardless of the duration of the control signal and the moment of its output, the first pulse to the output element 2Ш1И 10 coincides with the beginning of the positive half-period and the last with the beginning of the negative half-cycle of the mains voltage (diagram 26.) The pulses obtained in this way are fed to the input of the control pulse generator 11, which generates a thyristor control pulse 12 (diagram 27). As a result, the transformer 13, a network voltage is applied (diagram 28), the first half period of which is always positive and the last half period regardless of the duration of the command signal is negative.

The second variant of the device is simpler, but consumes increased power. In this case, it contains one amplifier-shaper 1, element 2 and 6, a one-shot 31 and a braked blocking generator 32 (figure 3).

The operation of the device in the second embodiment proceeds as follows. The synchronization unit with the network works in the same way (diagrams 14 and 17). Amplifier 4 generates positive impulses from impulses,

received at the output of the differential circuit 3 (diagram 18), which are fed to the first input of the element 2I. When a control signal is applied to the second input of this element, pulses also appear at the output (diagram 21), which trigger the one-shot 31 (diagram 29). The pulse duration of the one-shot 31 is set equal to the duration of approximately one and a half of the half-cycle of the mains voltage. The inhibited blocking generator 32, when a pulse of the one-shot 31 is applied to its input, generates a sequence of pulses that are used to control the thyristors 12. The duration of the generated sequence is equal to the length of the pulse of the one-shot (chart 30). The operation of the device according to the second embodiment is characterized in that for the operation of the blocking generator 32, an increased power supply of the control device is required.

Thus, the use of the invention makes it possible to simplify control circuits of anti-parallel-connected thyristors.

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Claims (2)

1. A device for controlling counter-parallel connected thyristors, comprising a synchronization unit with a network, an RS-trigger and a control pulse generator, characterized in that, for the sake of simplification, it is equipped with three amplifiers-shapers, a differentiating circuit and elements 2I and 2OR, the inputs of the first and second amplifier-drivers are connected to the output of the synchronization unit, the output of the first amplifier-driver is connected to the first input of the 2I element, the second input of which is designed to connect to the control source signal, and the output is connected to the first input of the 2 OR element and the input of the ^ -trigger, the output of the second amplifier-driver is connected to the input R of the RS-trigger, whose inverse output is connected through the differentiating chain and the third amplifier-driver to the second input of the 2 OR element, and the output of the element 2 OR connect to the input of the shaper control pulses. 2. A device for controlling counter-parallel connected thyristors, comprising a synchronization unit with a network and a control pulse shaper, characterized in that, for the sake of simplicity, it is equipped with a shaper amplifier, a 2I element and a one-shot, and the control pulse shaper is made in the form of inhibited blocking -generator, the input of the amplifier-driver is connected to the output of the synchronization unit, its output is to the first input of element 2I, 'the second input of which is designed to connect to the source I control signal, and the output is connected · to the input of the single-shot, the output of the single-shot is connected to the input of the shaper of control pulses.