Thyssen Industrie Ag

Helmut Grosser

Gerhard Holzinger

Jurgen Meins

Juergen Meins

A method and an apparatus are provided for determining the distance of a probe, particularly a magnetic bearing or a magnetic levitation device, from a conductive reaction rail. The probe comprises at least one sensor having at least two magnetically-coupled coils disposed opposite the reaction rail. The coils generate an alternating magnetic field whose influences (eddy currents) are detected by the sensor and employed for identification of the distance. In order to achieve a high, useful voltage level, insensitivity to external electrical fields and potential fluctuations, as well as a small influence of system-conditioned magnetic fields, the influences of eddy currents induced in the reaction rail by the alternating magnetic field are acquired and utilized for the identification of the distance.

Method and apparatus for determining the distance between an

In magnetic bearings and magnetic suspension devices, sensors (4), as they are used for bearing regulation of support and guide magnets in magnetic transportation technology, continuously measure the distance of a magnet (6) from a reaction rail (7), in order to obtain a signal with which the magnet (6) is controlled with regard to the energizing current in such a way that it remains suspended at the predetermined distance. In known devices, there is no accurate monitoring of the sensor signal, which can result in faulty regulation of the excitation if the sensor signal is faulty, which represents a significant safety risk. Accurate monitoring of the sensor function, in addition to the distance measurement, is acheived by having, in addition to the measurement coil (1) to which alternating voltage is applied, a second reference coil (2), which has only a slight magnetic coupling with the rail (7) and to which the same voltage as the measurement coil is applied, and that the difference current of the two coils is used to measure the distance and the difference current when an additional impedance is periodically switched in is used to check the device.

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Maisach, Germany

Helmut Grosser