DE1020731B - Capacitive voltage converter with a grounded divider capacitor - Google Patents

Description

GERMAN

The invention relates to a capacitive voltage converter with a grounded divider capacitor, the one in Resonance with the total capacitance, possibly connected in series with a choke coil Voltage transformer is in parallel.

With converters of this type, there is a burden-free or insufficiently burdened operation There is a risk that the entire circuit arrangement will stall when certain voltage values are exceeded is triggered, which then consists of the natural frequency of the undervoltage circuit from the sub-capacitor of the divider, the inductance of the additional choke and the no-load inductance of the voltage transformer, continue to oscillate underfrequently, because of the lack of sufficient Burden the damping is low. However, this changes the shape of the voltage curve on the secondary side strongly influenced, a voltage measuring instrument shows a value that is too high from the actual Secondary voltage, which corresponds to the prevailing high voltage in frequency and size, and one Superimposed low-frequency voltage results, which is not even present in the high-voltage circuit. as As a result, an excessively high high voltage is simulated with connected voltmeters, whereby display connected wattmeters practically correctly. It is known to have such low-frequency vibrations to prevent the secondary burden of the converter by an additional ohmic Resistance increases, but its ohmic value is the same at all frequencies and that also acts as a load acts when damping would not be required in normal operation. It is also known in the case of a capacitive voltage converter with a grounded divider capacitor, on its sub-capacitor a voltage transformer is located to provide means to prevent underfrequent disturbance oscillations to suppress, while current is not influenced by the operating frequency. In this converter, however, is also used to dampen the undesired low-frequency vibrations an ohmic resistor is used; the adverse effects of this resistance are said to be here be compensated by connecting a special compensation transformer in parallel. With However, this measure only suppresses tilting vibrations that are not symmetrical, ie. H. in which the currents are different on the primary and secondary sides. With symmetrical power distribution however, there is no damping for spurious oscillations.

All the disadvantages of the described known converters are very simply avoided in that, according to the invention, the primary and / or secondary winding capacitive voltage converter
with grounded divider capacitor

Applicant:

Messwandler-Bau GmbH,
Bamberg, Nürnberger Str. 225

Otto Graul, Bamberg,
has been named as the inventor

development of the transformer or parts of these windings at least one iron-closed choke coil is connected in parallel, the magnetic circuit is dimensioned so that below the operating frequency of the Converter saturation occurs, whereby the underfrequent S tor vibrations are suppressed.

A further advantage of the arrangement according to the invention is that when the normal network burden is connected and the operating frequency prevails as a result of its damping, the choke or chokes only act or act as a small, practically insignificant additional burden. Then occur underfrequency vibrations with approximately the same voltage, z. B. with 25 or 16 ² / s Hz, then the cores of the choke coils are much more saturated, and the inductance and thus the inductive resistance decreases so much that the burden is increased so that the low-frequency vibrations that occur are suppressed.

These chokes can be made using a core material that has a relatively has a sharp kink when saturation is reached, for example from sheet metal with a high nickel content. This Kink can be alleviated by adding siliconized transformer sheet to these sheets.

A choke according to the invention can, if necessary, have a secondary winding that can be tapped, as a calibration excitation for the compensation of the translation error and / or the incorrect angle of the Overall arrangement is used.

The choke according to the invention can, under certain circumstances, also place a load on the converter at 50 Hz represent, practically in the order of 15 to 20 VA and with an inductive Power factor of about 0.1. If converters are to be manufactured that have a high degree of accuracy, so z. B. class 0.2 transducers, then said inductive preload may be undesirable.

709 809/142

Claims (5)

According to a further advantageous embodiment of the invention, in such cases, the iron-closed choke coil or coils z. B. a capacitance is connected in parallel, which is dimensioned so that it takes about the same current as the throttle at operating frequency, for example at 50 Hz. With almost the same current consumption at operating frequency, the choke coil system with a capacitor connected in parallel has a very high resistance of several thousand ohms, so that there is practically no pre-load on the converter. According to the invention, it is not absolutely necessary to compensate so far that the current consumption of the choke and capacitor is the same; it is rather sufficient that the resulting current, which, because the two currents are phase shifted by approximately 180 °, represents their arithmetic difference, is kept within the desired limits. In this case, the converter is practically not loaded during normal operation at 50 Hz, but at the moment of the occurrence of low-frequency breakover oscillations due to the detuning of the 50 Hz resonance circuit, it is so heavily loaded that the low-frequency oscillations from 16 to 25 Hz cannot exist. Further features of the invention can be found in the attached circuit diagrams and in the following description. 1 shows a circuit according to the invention with a choke connected in parallel to the secondary winding of the voltage transformer, and FIG. 2 shows a section of the circuit according to the invention with a choke and capacitor connected in parallel with the primary winding of the voltage transformer. The high voltage applied to 1 leads via the upper capacitors 2 of the divider capacitor to the lower capacitor 3 and from there to earth. An additional choke 6 is connected between the upper capacitors 2 and the lower capacitor 3, the other pole of which is connected to the high-voltage winding 8 of the voltage transformer. The other pole of this winding is connected to earth. The choke 43 is located on the low-voltage side 26 of the voltage transformer and, as described above, forms a type of highly frequency-dependent additional burden. Terminals 33 and 34 are used to connect the regular burden. In the circuit according to FIG. 2, this choke 43 is connected in parallel to the primary winding 8 of the voltage transformer. A capacitor 44, which is additionally connected in parallel and whose function was described at the beginning, is indicated in dashed lines. According to the invention, such a capacitor can also be connected in parallel to the inductor 43 according to FIG. 1 located in the secondary circuit. Godparents ta ν s ρ p. C c h e: 1. Capacitive voltage converter with a grounded divider capacitor, which is in resonance with the Total capacity of working voltage transformer, possibly connected in series with a choke coil is parallel, characterized in that the primary and / or secondary winding of the transformer or parts of these windings have at least one iron-closed inductor is connected in parallel, the magnetic circuit of which is dimensioned so that saturation occurs below the operating frequency of the converter. 2. Capacitive voltage converter according to claim 1, characterized in that the core the choke or chokes consists of a material with a high nickel content. 3. Capacitive voltage converter according to claims 1 and 2, characterized in that Mixed cores made of normal siliconized and nickel-containing core sheets can be used. 4. Capacitive voltage converter according to claims 1 to 3, characterized in that the Choke has a secondary winding that can be tapped if necessary, which acts as a balancing excitation serves to compensate for the translation error and / or the incorrect angle of the overall arrangement. 5. Capacitive voltage converter according to claims 1 to 4, characterized in that to the iron-closed choke coil (s) is connected in parallel with a capacitance which is dimensioned in this way is that it draws approximately the same current as the operating frequency, for example at 50 Hz Choke or that at least the phase opposition, recorded by the choke and capacitor Compensate currents to such an extent that the resulting current remains within the desired limits. Considered publications:
German Patent No. 882 450;
Book: »Messwandler« by R Bauer, 1953, Berlin. 1 sheet of drawings © 709 809/142 12.57