SU813664A1 - Multichannel discrete phase-shifting device - Google Patents

Description

A 1-phase thyristor converter containing a constant-frequency pulse generator common to all channels, connected through a prohibition element to the first inputs of the counters, and in each channel, coincidence elements, control driver drivers and clock pulse drivers.

However, this device does not provide reliable control of the multiphase thyristor converter in the discontinuous current mode, when it is necessary to use two pulses that are shifted mutually on | b / n1 el.grad.

The purpose of the invention is to increase reliability.

To achieve this goal, the multichannel discrete phase-mover is equipped with a common for; All channels of the control system register, OR elements and comparators, moreover, the register is connected to the first inputs of the comparators, the second inputs of which are connected to the low-end outputs, counters connected by the second inputs to the outputs of the synchronizing pulse drivers that are common to the two channels, the outputs of the comparators through the first match entries and logical elements OR connection. with the inputs of the control pulse drivers, the second inputs of the matching elements are connected to the outputs of the higher bits of the counters.

1 shows a block diagram of a multichannel discrete phase shifter for. control three-phase thyristor converter} in FIG. 2 is a time diagram of voltages at the outputs of blocks of a phase-shifting device;

A multichannel discrete phase-shifting device contains a pulse generator 1, the output of which is connected to counting inputs of counters 3 through prohibition elements 2. The counter has N bits. The generator has a pulse frequency.

f - fn-:

where is the power supply frequency

thyristor converter The outputs of the formers of the 4 clock pulses are connected to the inhibiting inputs of the inhibiting elements and the installation inputs to zero counters The outputs of the bits of the register 5 of the control system are connected to the first inputs of the comparators b, the second inputs of which are connected to the first (M 1) bits of the counters, i.e. Comparators have in each discharge two paraphase inputs. Since the increase in the angle of control is directed opposite to the increase in the code on the counter, the comparison of the codes of the register of the control system and the meters must be made in the additional code. To this end, the outputs of the bits of the register of the control system nads. supply to the inputs of the comparators in accordance with and accordingly with the outputs of the bits of the counters 3 in those bits in which 1 is in the initial code, and in the remaining bits the connection must be opposite. The initial code for all channels in the case of a three-phase converter is defined as the code of the integer part of the number 2.. as a result, the comparison will be in the opposite code. For the comparison to be in. additional code, it is necessary to take 1 from the calculated value of the initial code.

The outputs of the comparators are connected to the first inputs of two coincidence elements 7, the second inputs of which are connected to the outputs of the higher discharge of the counters. The outputs of the matching elements are connected to the inputs of logical elements OR 8, the outputs of which are connected to the inputs of the control driver formers 9, which are then connected to the control electrodes of the thyristors.

Fig. 2 shows diagrams of the following voltages. At the outputs of the device blocks:

10 (Ug, Ujj, U (;) -phase voltage of the thyristor converter);

11, 12, 13 — pulsed voltages at the outputs of the shapers of 4 synchronizing pulses;

14, 15, 16 - voltages at single outputs of higher rg.zr counters 3 17, 18, 19 - voltage pulses

at the outputs of the comparators .6 at the moments corresponding to the initial codes, i.e. at the angle of regulation Oi 0-,

20,21,22,23, —double pulses of 24,25 voltages at the outputs of the drivers of the 9 control pulses. The device operates as follows 3 ohm.

Phase voltages 10 (and, Ug,, U (-) of the thyristor converter) are supplied to the outputs of synchronizing pulse formers .4. At the moments of voltage UQ, Uu, U0 passing through zero, for example, from the negative half-wave to positive at the outputs of the formers 4 clock pulses are generated by pulses of voltages 11, 12, and 13, which prohibit the passage of pulses from generator 1 to counters 3 and simultaneously set them to zero. Thus, the start of counting of counters 3 is synchronized with the thyristor voltage reobrazovatel.

In register 5, the control system finds the code defining the phase shift of the thyristor control pulses relative to the initial code; at the moments of coincidence of the code of the counters 3 present at the outputs, comparators 6 increase the pulses whose temporal position relative to the initial code is proportional to the control code. Performing a paraphase comparison of the control register codes 5 with the counter codes 3 allows the code on register 5 to change downwards until the codes coincide, which contributes to an increase in speed when the error is processed by the automatic control system as a whole. Since the comparators 6 are connected to the lower (N-1) bits of the counter 3, two impulses appear at the outputs of the comparators b for the period of the voltage of the thyristor converter. Thus, for example, for a phase Ud of the supply voltage, the first pulse corresponds to the control pulse of the thyristor in the anode group, and the second to the fourth thyristor in the cathode group of Fig. 2. The formation of two control pulses during the period of the supply voltage of the thyristor converter allows to obtain a symmetric system of control pulses, independent of the distortion of the form of the supply voltage. With the help of the coincidence elements 7 - controlled voltages from the outputs of the higher bits of the counters 3, and the logical elements OR 8, the pulses are distributed over the thyristor control channels. As a result, a periodic sequence of double pulses with a frequency equal to the frequency of the supply voltage of the thyristor converter, with a phase proportional to the code of the control angle c and shifted mutually by an electric angle equal to It / m, is present at the outputs of the control pulse formers 9. This ensures reliable control of the thyristor converter and the mode of intermittent currents at small control angles. The control system associated with registrams 5 provides the necessary law for regulating the phase of the control pulses of a multichannel phase-shifting device for controlling the thyristor converter, including limiting the maximum and minimum control angle.

ten

Claims (3)

1. USSR author's certificate number 465704, cl. H 02 R 13/16, 1971. 2. USSR author's certificate 5 No. 647833, cl. H 02 R 13/16, 1977. 3. Authors certificate of the USSR 550755, cl. H 02 P13 / 16, 1974.