SU57616A1 - Device for smoothing pulsations of rectified voltage - Google Patents

Description

Already known are devices for smoothing pulsations of rectified voltage in mercury rectifiers by applying a third harmonic frequency to the anode voltage with the help of a triple.

According to the invention, in such a device, in order to obtain an automatic phase change of the third harmonic depending on the rectifier load, the transformer, power supply rectifier, is driven to the intermediate points of the frequency triple winding connected directly to the supply network.

In FIG. 1 shows a diagram of the proposed device, FIG. 2 shows the stress curves of the known devices for smoothing the pulsations; FIG. 3-5 voltage curves of the proposed device.

The secondary voltage of the three-phase triple of the frequency T, U, connected to the primary circuit of the transformer TI, which supplies the mercury rectifier 5 (Fig. 1), is known to have a frequency of three times the frequency of the primary voltage. With a serial connection of each phase of the secondary winding triple frequency T, U with. By the corresponding phase of the primary winding of this transformer TI, the curve of the secondary voltage of the transformer as a result of the application of the third-harmonic voltage on the voltage of five times the frequency of the periodic frequency has, as shown in FIG. 2, oblate shape. FIG. 2, curve 1 represents a sinusoid of a five-period frequency, curve 2 is a third harmonic of this frequency, and a curve 5 is the resulting voltage at the terminals of one phase of the secondary winding of the transformer.

The curve of the rectified voltage at idle will be in the form of a straight line, i.e. the pulsations will be practically zero.

However, as the load increases, the ripple magnitude will increase dramatically if the beginning of the third harmonic coincides with the beginning of the main (five times periodic) sinusoid. In order to have a small percentage of pulsations with a large percentage of the load, the third harmonic curve must be shifted in phase so that the secondary voltage curve of the transformer has some peak in the first quarter of the period, as shown in FIG. 3

This phase shift of the third harmonic should be made at a relatively small angle. FIG. 4 and 5 show the shape of the rectified voltage curve for the case of overlapping anode burning by 30 (Fig. 4) and 40 (Fig. 5). In the first case, the third harmonic shift must be made by 5 °, and in the second case by 10 °. The overlap angle of burning anodes at 40 ° is maximum with the simultaneous burning of two anodes and a further shift in the third harmonic phase, therefore there is no need.

The phase shift of the third harmonic, depending on the magnitude of the overlap angle, according to the invention, is carried out automatically. As can be seen from the diagram shown in FIG. 1, the primary winding of a power transformer T-, supplying a mercury rectifier, is connected not directly to the buses, as the primary winding of the frequency tripler, but to the intermediate points of this primary winding. Due to this, the current consumed by the power transformer on the higher voltage side, i.e., a current proportional to the load current of the mercury rectifier, will pass through several turns of the primary winding of the frequency multiplier, causing additional magnetization in its magnetic circuit.

The authors' experiments with frequency multipliers showed that a change in the saturation of the magnetic circuit strongly affects the shape of their secondary voltage curve, namely, an increase in saturation causes a peak in the first Thursday of the period (as shown

in fig. 3) and causes a phase shift of the third harmonic curve. This property of the frequency tripler makes it possible to have an automatic shift of the third harmonic curve depending on the magnitude of the load of the mercury rectifier. The required additional saturation in a practical scheme can easily be determined by calculating and selecting the number of ampere turns of the part of the primary winding of the triples of the frequency through which the current consumed by the power transformer passes.

The theoretical calculations done by the authors showed that in the case of the mode, respectively, FIG. 4, the ripple of the rectified voltage is about 2%, and for FIG. 5 pulsations are in the order of 3%. By switching on the rectified voltage of the small reactor P on the side, it is possible to easily reduce the magnitude of the pulsations to a value equal to 0.2-0.3%, i.e. practically imperceptible.

The scheme proposed by the authors eliminates heavy reactors and filters.

The subject matter of the invention.

A device for smoothing pulsations of a rectified voltage in mercury rectifiers by applying an anodic voltage to the anode voltage using the third harmonic frequency triple, characterized in that in order to obtain an automatic change of the third harmonic phase depending on the voltage of the rectifier, the transformer that supplies Mitel, Adventure to the intermediate points of the winding frequency triple, connected directly to the mains.

E to the author's certificate of E. A. Ivanov and N. N. Kostromitin No. 57616

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E to the author's testimony of E. A. Ivanov N. N, Kostromitin “Ms 57616

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