SU561272A1 - Phase control method of frequency converter - Google Patents

Description

one

The invention of mercury is related to the methods of phase control of thyristor converters of single-phase current into three-phase, lower regulated frequency.

The known single-channel method of phase control of thyristor converters in which the formation of the phase of the triggering pulses for all thyristors is carried out in a single canape with the subsequent distribution of pulses over the thyristors ci using a switch lj. This method is implemented using a complex and unreliable scheme.

There is also known a method of phase control of multiphase converters on controlled valves, in which the initial pulses produced by generators shift in phase-shifting channels, the number of which is chosen to be twice as small as the number of phases, and pulses are fed into each channel with an interval of 180 al. hail and then distributed over antiphase thyristors 2j.

This method, which is closest to the one proposed, allows the pulses to be distributed through the matching blocks by applying to the second input of these blocks the corresponding linear voltages.

The described method is not applicable to converting a single-phase current into a three-phase under-controlled frequency, since, firstly, for the thyristors of the specified converter, at the conduction intervals, there is no one-to-one correspondence with the polarity of the anode voltage and the need to apply a control pulse, (and secondly In order to ensure the stable operation of the converter with an active - inductive load, it is necessary to supply thyristors in the required sequence with auxiliary investment pulses.

The aim of the invention is to expand the scope of the vi3BecTHoro method.

The goal is to achieve Tt.vi, which, before the distribution of the formed and shifted rectifier pulses delivered to each channel of the phase-shifting unit through 180 el. hail., the pulse sequence from the output of the phase-shifting unit is selected in time together with the inverter pulses according to the sign of their temporal position relative to the initial rectification pulses, the frequency of which is equal to twice the frequency of the supply voltage.

FIG. 1 shows a flowchart implementing the G1-proposed method; in fig. 2 transducer; single phase voltage to three phase.

The block diagram contains a generator of initial images 1 | phase-matching device 2, time selector 3, distributor, pulses 4 with cells 5 and 6. The circuit is designed for controlling single-phase to three-phase voltage transducers, (see Fig. 2) containing thyristors 7-18.

The control of the converter according to the proposed method is performed as follows.

The initial pulse generator 1 associated with the mains supply generates short-term single-pole pulses with an interval of 18 ° el. degrees, which come from its output, to the input of the phase-shifting device 2. The phase of the initial pulses coincides with the moments of zero crossing of the supply voltage. In device 2, the initial pulses are shifted by the required angle, determined by the value the control voltage From the output of the phase-shifting device, the rectifying pulses, together with the inverter, arrive at the time selector 3, where the input sequence is divided into two. The operation of the time selector 3 controls the sequence of selector pulses, the role of which in the case under consideration is performed by a sequence of initial pulses.

The pulses of the first and second sequences from the first and second outputs of the selector 3 enter the cells 5 and 6 of the distributor 4 pulses.

Both cells have six outputs each, with cells 5 connected to the converter thyristors providing load current flow to odd in terms of the supply voltage, and cell outputs 6 to t with pistols playing the same role in even half periods. By this

rigid phasing of the control impulses entering the thyristor control circuits with anode voltages is provided.

The necessary logic of the operation of the distributor of 4 pulses is determined by the signals from the master device. In each half-period of the supply voltage, the input from the cells 5, 6 is implemented a logical operation AND, resulting in the required three outputs; This cell produces control pulses arriving at the corresponding thyristors of the converter. The frequency of the output voltage of the converter is a function of the frequency of the signals of the driver.

Thus, the proposed control method can be used for single-channel control of single-phase to three-phase converters.

Claims (1)

Invention Formula The method of phase control by the frequency converter using a phase-shifting unit, the number of channels is twice as small as the number of phases, consisting in the formation of initial contractile pulses, shifting them, fed to each channel of the phase-shifting unit through 180 el. hail, and then distribute them together with inverter pulses across the antiphase operating thyristors of the converter, characterized in that, in order to expand the area of the drimenens before the distribution, the impregnation impulses from the output of the phase-shifting unit are selected in time together with the inverter pulses at. the sign of their temporary position relative to the initial rectification pulses, the frequency of which is equal to twice the frequency of the supply voltage. Sources of information taken into account in the examination. 1, V.L. Ankhimyuk, et al. Single-channel rectifier control system with a gate. ignition angle range. Electrical Engineering, № 11, 1970, p. 8-10. SL, USSR Copyright Certificate No. 2239OO, and O2 p 13/16, 1967 (prototype). To thyristor preo60azoatel