SU658675A1 - Synchronizing device - Google Patents

Description

one

The invention relates to a converter technique, in particular for thyristor frequency converter control systems, powered from autonomous electrical sources of comparable power, with a voltage frequency varying within wide limits.

Converter control systems are known that are powered from a source with a constant frequency of the supply voltage, in which filters 1 are included in the synchronization circuit to eliminate distortions in the supply voltage.

However, in the case of power supply of thyristor converters from autonomous electric sources of comparable power, the voltage frequency of which can vary within fairly wide limits, it is impossible to eliminate the influence of the distortion of the supply voltage on the control system operation using filters.

The closest technical solution to this is a synchronization device for control systems of thyristor frequency converters fed from an autonomous energy source of comparable power, containing

transformer, to the secondary winding of which the bases of transistor switches are connected, the emitters of which are combined and connected to the middle point of the transformer, and R-S trigger 2. The purpose of such drivers of synchronizing pulses is to bring the supply voltage, distorted by switching processes, to synchronous pulses with them. The high sensitivity of such circuits ensures the absence of a phase shift between the supply voltage and the rectangular voltage corresponding to this voltage.

However, with an increase in load currents, the switching distortion of the supply voltage increases. Due to the presence of capacitance and inductance in the circuit

5, as well as due to the presence of parasitic capacitances and the leakage inductances of the matching transformers, high-frequency disturbances appear at the input of the trigger circuits, which cause a false trigger of the synchronizing pulse drivers. This greatly reduces the reliability of control of the converter.

The purpose of the invention is to increase reliability by preventing the R-S trigger from interfering with the switching of thyristors.

The goal is achieved by the fact that a synchronization device for thyristor frequency converter control systems powered by an autonomous energy source of comparable power, containing a synchronization pulse shaper, which consists of a transformer, to the ends of the secondary winding of which are connected bases of transistor switches, the emitters of which are combined and connected to the middle point of the transformer, and RS trigger, additionally introduced four logical elements AND-NOT, logical element AND AND-NOT, thyristor state sensor, pulse shaping unit by differential, and connected to the collector of each of the transistor switches are AND-NOT connected in pairs, the outputs of the last AND-NOT logical elements are connected to the RS trigger input, the output of which is connected through serially connected a pulse shaping unit with respect to a differential and a one-shot is connected to one of the inputs of an OR-NOT logical element, the output of which is connected to the second inputs of the last pairly connected AND logic - NOT, and the second input is connected to the output of the switching presence unit, to the input of which the thyristors state sensor is connected.

The drawing shows a block diagram of a synchronization device for a single phase.

The device contains one clock generator (PSF), the number of which is usually determined by the number of phases of the power supply. The VIF unit consists of a matching transformer 1, the secondary windings of which are connected through resistors to the base of transistor switches 2 and 3, working in antiphase in the key mode, the collectors of transistor switches are connected to the AND-NOT logic circuits 4, 5, respectively, performing inversion functions. The outputs of logic circuits 4, 5 are connected respectively to the inputs of logic circuits AND-NOT 6, 7. The output of logic circuits 6, 7 is connected to the other inputs of logic circuits 6, 7 and the outputs of the RS trigger 9. Sensor the thyristor 10 state is turned on to the input of the switching availability unit 11, which is connected to one of the inputs of the OR-NOT 8 logic circuit, ensuring that the RS of the trigger 9 is not activated for the entire switching time.

The input of the pulse shaping unit by differential 12 is connected to the output of the PSI block, and the output of block 12 is connected to the input of the one-shot 13. The output of the one-shot 13 is connected to another input of the OR-NOT 8 logic circuit, providing for some time a fast ban on the triggering of the R-S trigger 9.

A linear voltage of the power supply is applied to the VIF input through a matching transformer 1. From the secondary windings of the transformer, the antiphase voltages are supplied to keys 2 and 3, operating in key mode. After the linear voltage passes through zero to a positive value region, the transistor 0 key corresponding to this half-wave voltage goes into saturation mode and a logical zero signal passes to the input R-S of the flip-flop 9, which switches the R-S flip-flop 9 to the opposite state. The output from each VIF is fed to a pulse shaping unit by a differential of 12. The purpose of block 12 is to produce short pulses with each switch of the trigger circuit. These pulses are fed to the one-shot 13, which produces a prohibition pulse. The inhibit pulse through the logic circuit OR-NOT 8 passes at a speed equal to the speed of the signal passing through blocks 12, 13 and determined by the number of integrated circuits in these blocks. In this case, for the time specified by the single vibrator 13, a ban is imposed on the passage of a switching noise signal to the input of the R-S trigger 9. Since the signal passage time through the blocks 12, 13 is an order of magnitude shorter than the turn-on time of the thyristor, the ban on the R-S trigger

0 earlier than the cause of high frequency noise. Due to the fact that the frequency of the supply voltage varies within 1–4, the duration of the inhibit specified by block 13 is within 10 ° C 40 °. This leads to the need to prohibit the entire switching time from the switching presence sensor 11 as well. From the thyristor status sensor 10 to the input of the switching presence block 11, information is received about the presence of one or another thyristor in

g conductive. So for a three-phase scheme in the case of two cathode or thyristors. anode group in the conductive state, which corresponds to the presence of switching, block 11 performs the logical function of “voting two out of three, while

s the prohibition signal from block 11 will go to the OR-NOT 8 logic and will prohibit the switching signal from passing to the R-S trigger for all the switching time. Naturally, the ban on this channel

comes after the start of switching.

Claims (2)

Invention Formula A synchronizing device for thyristor frequency converter control systems powered from an autonomous energy source of comparable power, containing a synchronizing pulse generator that consists of a transformer, to the ends of the secondary winding of which are connected bases of transistor switches, the emitters of which are combined and connected to the middle point of the transformer and RS trigger, characterized in that, in order to increase reliability by preventing the RS trigger from being triggered from interference, it It is equipped with four NAND logic elements, an OR NI logic element, a thyristor state sensor, a switching availability unit, a single vibrator and a pulse shaping unit with respect to the differential, and connected in series to each of the transistor switches are connected NAND logic elements the last longitudinal elements of the NAND are connected to the RS input of the trigger, the output of which is connected via one of the consecutively connected pulse shaping units to the one-shot The output of an OR-NOT logical element, the output of which is connected to the second inputs of the last pairwise connected AND-NOT logical elements, and the second input of the OR-NOT logical element is connected to the output of the switching presence unit, to the input of which the thyristor state sensor is connected. Sources of information taken into account in the examination 1. Pisarev A. L. and others. Control of thyristor converters. M., “Energie, 1975, p. 67. 2. "Electricity number 3, 1976, p. 55. p.55. P