The present paper deals with investigations concerning optical magnetic sensors. The most important advantage of sensors of this kind is their safety of service and insulating power. The insensitiveness of optical sensors to electromagnetic interference was discussed and experimentally investigated. The experimental investigations were concentrated on the adequate sensing fibre as well as on the sensor based on the bulk glass cylinder. The paper presents the results of magnetooptic tests of the elaborated magnetic field optical sensors and conclusions arise from them.
Today the parameters and characteristics of permanent magnets are determined by means of computer as well as analogue‐to‐digital technics. Also digitizing oscilloscopes owing to the advanced digital processing of measured signals may contribute to the processing of measured data (averaging interpolation) and in mathematical operations. The measuring and calculation possibilities together with the possible rapid change of the magnetic state of a magnet due to the pulse magnetization makes the pulse test methods of magnets more and more frequent. The application of either single‐pulse or multiple‐pulse methods is possible. The idea of measurements when using both the latter methods is based on the assumption that the magnet before being subjected to tests is magnetized up to the saturation state. The single‐pulse method described briefly in and more comprehensively in, consists in recording and suitably processing the set of discrete values having a finite number of elements which appear during a single remagnetizing pulse of the magnet. The range of the recorded values covers flux densities from −Br to +Br i.e. covers one half of the hysteresis loop. In consequence, it is necessary to apply in this procedure a magnetic field k‐times exceeding the coercive force HcB of the tested magnet (depending on its type).
The authors presents mathematical models of hysteretical relations of main magnetic parameters in pulse measuring procedures. Fragments of hysteresis loop specific for assessment of magnets as well as particular hysteresis parameters are discerned.
The authors of the presented paper deal with investigations concerning applications of the optical fiber sensor of the magnetic field in electric DC engines with permanent magnets. The aim of the sensor is to measure the state of magnetization of permanent magnets (basing on the measurements of magnetic field induction). The knowledge of the state of magnetization helps to decide whether permanent magnets need to be additionally magnetized in order to prevent damages of the whole engine. This can be done automatically, even when the engine is running. For the purpose the Faraday magnetooptic effect is used. The presented investigations concern an optical fiber sensor of the magnetic field provided with a glass rod characterized a high value of the Verdet constant as the sensing element. Thanks to the application of optical fibers the connection of the sensor head with the whole measuring system is constructed of insulating material without using of electrical connections.
Magnetic field analysis of a permanent magnet put in free space can be effectively performed by a boundary-integral technique completed with an iterative procedure following a non-linear magnetic curve of magnetic material. The general idea of the boundary-integral model of the permanent magnet is presented, the iterative algorithm and test software are described and the results of test computations are shown.
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