Siemens Aktiengesellschaft

Siemens Ag Osterreich

Adaptive Regelsysteme Gesellschaft M.b.h.

Adaptive Regelsysteme Gmbh

Albert Leikermoser

Peter Hamberger

A device for reducing a magnetic unidirectional flux component in the core of a transformer includes at least one compensation winding, which is magnetically coupled to the core of the transformer, at least one switching unit in series with the compensation winding to feed a current into the compensation winding, and at least one current-limiting reactor in series with the compensation winding, wherein two switching units are connected in parallel with each other per current-limiting reactor and the current-limiting reactor comprises two windings, which can be connected either in series or in parallel with each other, in order to reduce the number of current-limiting reactors in comparison with conventional cascaded circuits.

Device and method for reducing a magnetic unidirectional flux component of a transformer core

An arrangement for reducing a DC field component in the core of a transformer includes a compensation winding magnetically coupled to the core of the transformer, and a DC generator arranged in series with the compensation winding and with a reactance dipole. The reactance dipole is formed from a parallel circuit of an inductance and a capacitor to feed into the compensation winding a compensating current opposite in sense to the DC field component in the core. The inductance is formed from magnetically coupled first and second windings having Nand Nturns respectively, such that N/N&#x3c;1. The first winding is connected on one end to the DC generator and on the other end to the compensation winding. The second winding is connected in parallel with the capacitor. The magnetic coupling of the first and second windings is established via a soft magnetic core having an air gap.

Arrangement and method for the compensation of a magnetic unidirectional flux in a transformer core

A device for reducing a magnetic unidirectional flux fraction in the core of a transformer is provided. The device has a measuring device that provides a sensor signal corresponding to the magnetic unidirectional flux fraction, a compensation winding that is magnetically coupled to the core of the transformer, a switching unit arranged electrically in a current path in series with the compensation winding in order to feed a current into the compensation winding. The action of the current is directed opposite to the unidirectional flux fraction. The switching unit can be controlled by a regulating variable provided by a control device and can be switched into a conductive state during a predefined time interval and in accordance with the regulating variable, the switch-on time being mains-synchronous. A device for limiting the current in the current path is provided and the sensor signal is fed to the control device.

Device and method for reducing a magnetic unidirectional flux fraction in the core of a transformer

A technique is provided for detecting a magnetic characteristic variable in particular the magnetic field strength in a section of a core permeated by a magnetic flux. A portion of the magnetic flux is branched off from the core and passed via a magnetic shunt branch, in which at least one non-ferromagnetic gap is formed. A shunt part is disposed in the shunt branch, wherein the magnetic material of the shunt part is not saturated. At least one section of the shunt part is wound with at least one sensor coil in which the branched-off portion of the magnetic flux generates a sensor signal by induction. The magnetic characteristic variable is determined from the branched-off portion of the magnetic flux or a variable derived therefrom using a sensor and evaluation device to which the sensor signal is fed.

Method and apparatus for detecting a magnetic characteristic variable in a core

An electrical transformer with unidirectional flux compensation is provided. The transformer includes a soft magnetic core on which a primary winding arrangement, a secondary winding arrangement, and a compensation winding arrangement are arranged. The compensation winding arrangement is connected to a current control device which feeds a compensation current into the compensation winding arrangement using a control signal. A magnetic field measuring device measures the magnetic field in the core of the transformer or the stray magnetic field that closes outside the core via an air path and provides the control signal.

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Salzburg, Austria

Albert Leikermoser