SU48760A1 - AC rectifier - Google Patents

Description

|::: p. | ;;. : i.; W Iff and | .Yag: i: fajsj-. ft y; f;: t; l: - sj; ,; . .YJ jpcr- ciif. ill - And | l-ii 1 pc f :: .r Iff AUTHOR'S CERTIFICATE FOR INFORMATION DESCRIPTION P devices for rectifying alternating. To the author's testimony by G.I. Babat, for the last 7 December 1935 (cf. first number 181783). On the issue of the author's testimony was published on 31 August: the mouth of 1935. The main disadvantage of the currently used control schemes The problem is the deterioration of the power factor in the power supply network at a lower level when it is lowered at the same time as the ignition angle. A number of circuits of controlled rectifier circuits are known, in which it is possible to achieve or even advance. However, these schemes are characterized by considerable complexity and inconvenience of adjustment. The present invention proposes a converting device that allows the amount of rectified voltage to be adjusted, but at the same time any cosf in the supply network. In FIG. 1 shows a schematic diagram of the proposed device; FIG. 2 - corresponding curves of currents and voltages; FIG. 3 is a modification of the circuit shown in FIG. one; FIG. 4 curves of currents and voltages corresponding to the diagram of FIG. 3. In FIG. 1 a schematic diagram of the device 1 and 2 represent the AC network, the anode transformer, and the main thyratron (enes, zero valve, and b and auxiliary (extinguishing) thyratrons, C-capacitor constant capacitance, 3 and 4 network The moment of ignition of the main thyratrons L and L is controlled by a Fu fuser and a single transformer 1. The moment of ignition of extinguishing Tiratroi a and b is controlled by means of a phase-free Phl and piciky transformers P "and /". Figure 2 shows krppie currents and voltages in the scheme of Fig. 1. Curves Oeny for the case of the Plymot's inductance of a smoothing Drossel L |,. Upper curve, circled by a bold line, is the same as the one between the cathodes of the main valves and the bullet point of the anode transformer G ,, /, / and /. - the anode currents of the L, B and Z thyratron. : L and fj is the voltage applied to the mains supply, curve b, is the voltage between the cathode and the anode of tiratro 1a, LD / f is the voltage drop on the tiratron. At ti, tiratron A. is ignited. always, denoted a, At time f., a positive pulse is applied to the grid of the thyratron a.

In moment 2, a voltage is present on the capacitor C; at the same time, the potential of the left facing is negative, while the right is positive. Therefore, when a thyratron b is ignited, the voltage at the anode of the thyratron A takes on. A negative value (as can be seen from the curve of fig. 2) and the thyratron A goes out.

The capacitor G then recharges (on the right-side plate, on the left -J-) and the voltage at the anode of the thyratron A again becomes positive. However, with a suitable capacitor capacitance C, the residence time of the negative voltage at the anode of the thyratron A, the angle y, can be obtained sufficiently. so that the tiratron A had time to ionize. Therefore, after time t, the thyratron A will turn out to be blocked by a negative grid voltage and the load current will flow through the zero gate Z. The angle of extinction of the Tiratrons is the interval, denoted by E.

. After at time t the capacitor C recharges, both quenching thyratrons a and b are locked, therefore, a new recharge of the capacitor at the moment of zero crossing of the voltage curve of the transformer T (at time f) cannot occur.

At the moment 3 it starts to conduct a current tiratron V.

At time ti, a positive pulse is applied to the grid of the thyratron A and, thus, a negative voltage is applied to the anode of the thyratron B and the last goes out.

Condenser C is again recharged (its polarity becomes as shown in parentheses), and thus capacitor C is prepared to put out the thyratron L. at time 4

Thus, with the aid of the Fu phase shifter, the ignition angle of the main A – B thyratrons can be adjusted, and with the help of the Fe phase shifter, the extinction angle E of the phase thyratrons can be adjusted.

FIG. 3 shows a modification of the proposed device. In the diagram of FIG. 3 there is no zero valve and therefore

when one of the main valves goes out, another main valve lights up immediately.

The curves of currents and voltages in the circuit of FIG. 3 are given in FIG. four.

Ignition control of all thyratrons is performed in the circuit of FIG. 3 using one common phase shifter Фs and peak transformer P ,. The OG windings of the transformer Pn are made so that positive pulses are simultaneously applied to the nets A and a. In this case, the thyratron B is extinguished and the current passes to the thyratron A. Then a positive pulse is applied to the nets of the thyratrons B and B. Then the thyratron A is extinguished, and the load current is transferred to the thyratron B.

It is quite obvious and the possibility of the proposed schemes in the inverter mode. In the diagram of FIG. 3, this is achieved only by the polarity variable (the polarity corresponding to the inverter mode is marked on terminals 3 and 4 in brackets) and the corresponding setting of the phase shifter Fo.

In the diagram of FIG. 1, for operation in the ip-converter mode, it is necessary to supply the zero valve with a grid and control its double-frequency pulses (as compared with the frequency of the power supply network).

FIG. 1 and 3 single-phase conversion circuits are shown. Such schemes can find application in electrical technology.

To straighten or invert a multiphase current, the converter circuit must be composed of single-phase converter groups connected in series or in parallel using separation chokes.

When considering the circuits of FIG. 1 and 2, the question naturally arises whether, instead of using capacitor C as a quenching capacitor, it is not simpler to hit it directly to terminals 1 and 2 so that it compensates for the leading-in current drawn by the converter with its leading current.

However, with this inclusion to completely eliminate the phase shift in the supply network, the capacitor volt-amps must be equal to t / / sin Ф, that is,