SU892601A1 - Device for control of direct frequency converters based on thyristors - Google Patents

Description

(54) CONTROL DEVICE FOR DIRECT THREE FREQUENCY CONVERTER

I

The invention relates to a converter technique and can be used in control systems of direct frequency converters on thyristors. . Direct frequency converters are known to use frequency converters to control the quality of their output voltage, the tracking control channel, and a t-phase control system of program type GO is used to distribute the tracking channel pulses.

The closest technical solution to the present invention is a device for controlling a direct thyristor frequency converter containing a programmed t-channel control system and a t-phase additional transistor on the thyristors, in the cathodes of each branch of which a power generation thyristors, and in the load circuit - a semiconductor block, the control input of which is connected to the source of pulses of the tracking control channel f2j.

A disadvantage of the known devices is the small range of variation of the control angles of the power thyristors of the converter under the action of the signals of the tracking control channel.

10 and the possibility of irreversible failures in the formation of the output voltage of the converter.

The purpose of the invention is to expand the range of the following channel.

IS control and power quality of the output voltage of the converter by eliminating the possibility of formation malfunctions.

The goal is achieved

20 by the fact that m parallel chains of successively connected capacitors and transistors connected to a DC power source are additionally introduced into the converter control device; their control circuits through transformers are connected to the supply voltage, the common connection points of the capacitors and transistors in each chain are connected corresponding to the anodes of the thyristors, the branches of the additional rectifier, and the cathodes of the thyristor circuits of the rectifier of the rectifier include diodes, common points Connections which nodes J generating a control pulse power thyristors through additional thyristors connected to the output ktaocha next channel. FIG. 1 shows the principle of the electrical circuit of the device; in fig. 2 - timing diagrams illustrating the operation of the device. The control unit in relation to one group of valves of the t-phase frequency converter contains a low-power rectifier on thyristors 1-3, the circuits of whose cathodes include nodes 4-6 of generating control pulses of the power thyristors of the converter and developing diodes 7-9. The control circuits 10–12 thyristors 1–3 of the rectifier are connected to the same outputs of 10–12 t-channel control systems 13 of program type, and the signal of the program control channel formed when comparing the reference voltage of one phase (for example, phase A) of the supply voltage and a control voltage, is fed to the input of that of thyristors 1-3, which form the control pulses of a power thyristor belonging to the next phase of the fifth voltage (for example, phase c). The anode circuits of thyristors 1-3 are connected respectively to the connection points of capacitors 14-16 and transistors 17-19, forming 1 x m parallel circuits and connected to a constant voltage source. Transistors 17-19 are controlled from the secondary windings of transformers 20-22 whose primary windings are connected via a ballast resistance to the supply voltage (phase A-m). The signals of the servo control channel by the converter are fed to the input of transistor switch 23, and the common connection points of diodes 7–9 and nodes 4–6 of forming pulses of each branch 1 of the rectifier are connected via additional thyristors 24–26 to the output of key 23 of the next control channel, the thyristor control circuits 24-26 are connected to the outputs 1012 of the software control channel 13. In direct accordance with the supply mains phases, the high-resistance resistors 27-29 connected between the zero point and the cathodes of the thyristors 1-3 ensure the flow through for the last holding current. The device works as follows. At time t (Fig. 2), corresponding to the time of the transition through the supply voltage zero (phase A), the pulse transformer 20 provides a pulse to the input of the transistor 17, which is turned on and the capacitor 14 is charged from a DC source. Similarly, at the moment of passing through zero, the voltages of the other supply phases charge the remaining capacitors. Let the program control channel signal, obtained at the moment of comparing the reference voltage corresponding to phase A of the supply voltage, and the control voltage of the program channel .ftp arrive at input 10 of the thyristor 2 at time tj (Fig. 2b). The thyristor 2 is turned on and a current commensurate with the holding current of the thyristor 2 is flowing through the high-resistor 28. At the same time, the output voltage of the converter is compared with the reference control voltage of the next control channel (.t the moments of equality of positive and negative mismatch of the compared voltages are generated pulses of the tracking control channel (Fig. 2d). The control pulse of the tracking channel arrives at the time t at the input of the transistor 23, which opens, bridges the resistor 28, and through the node 5 forms the control pulses of the power thyristor passes a current (circuit 5-2-5-8-23), as a result of which node 5 generates a control pulse of the power thyristor of phase B. In order for the signals of the program channel not to surpass the signals of the next control channel it is necessary generate program channel pulses at a lower level of control voltage.

In order to prevent the formation of the output voltage by the following control channel in case of accidental failure, an irreversible breakdown of the formation did not occur, the control pulses of the program channel are used not only as recording pulses, the output of which is generated by the pulses of the control follower channel, but also for an independent photo. 1, control pulses of the power thyristors of the converter.

To do this, serve thyristors 24-26, unlocking each of which is performed simultaneously with the corresponding α-agistor of groups 1–3 of the same name as program channel pulses, the phasing of the latter corresponding to the phasing of the power thyristor control pulses removed from the pulse-forming units 4-6.

Thus, two control pulses arrive at the power thyristors: an impulse corresponding to the following channel, under the action of which the output voltage of the inverter is formed, and the control impulse lagging behind it, which is It is the duty of the relation. As a result, not only the distribution of the pulses of the tracking control channel is achieved with a wide range of variation of the control angles of the power thyristors, but also the quality of the output voltage is The power of the frequency converter is eliminated by the failure of the formation of its output voltage.

Claims (2)

1. A direct thyristor frequency converter control unit containing a programmed t-channel control system and a t-phase additional 92601 " a rectifier on thyristors, in the cathode circuit of each branch of which a thyristor control pulse shaping unit is connected, and in the circuit (load - a semiconductor switch, the control input of which is connected to the source of the control channel, characterized by T & neither the quality of the energy of the output voltage of the converter and the expansion of the range of action of the tracking control channel, the device is additionally connected to the device IS of direct current m of parallel chains of series-connected capacitors and transistors of control circuits, whose circuits are connected to transformers through a transformer, are connected to the thyristors of the corresponding branch of the additional rectifier, and in the circuits of the thyristor cells of the same branches of the rectifier, diodes are consistently connected, the common points of connection of which with the nodes of formation of the control pulses of the power thyristors through Additional thyristors are connected to the output of the key of the tracking channel. 2. The device according to claim 1, of which is, in order to simplify, as the source of the reference voltage of the program channel M controls use the voltage on the aforementioned capacitors. Sources of information taken into account in the examination I. Grabovetsky G.E., Zinoviev G.S., Stalinkin B.A. A tracking control system for direct coupled frequency converters. Sat Conversion technique, book. 2, Novosibirsk, NETI, 1968, p. 259-268. 2. USSR author's certificate according to application no. 1326917/07, 1969. c / fefffe / jf FIG. one 1 2 5 6 1 2 3 f 2