Digital compensating ferrometer

Abstract

A ferrometer with compensation conversion intended for plotting hysteresis loops of soft-magnetic materials is discussed. The ferrometer consists of a magnetization module, two identical magnetic induction and field intensity measuring channels, a control microprocessor, and a display module. The operating principles and metrological characteristics of the ferrometer are described.Most information on the properties of soft-magnetic materials (SMM) is provided by hysteresis loops and their parameters. The coordinates of the hysteresis loop points are converted with an analog-digital converter into coupled digital code pairs stored and processed in a microprocessor. The implementation of this method requires quite complex and expensive automatic systems [1]. Another method is to use instruments based on the ferrometric approach [2]. These instruments are relatively simple and inexpensive. The F5063 ferrometer formerly manufactured in the Ukraine belongs to them. No such instruments are now manufactured in Russia. At the same time, they are very useful since by measuring hysteresis loops one can easily find many characteristics and parameters of SMMs.As is well known [2], the ferrometric method consists in phase-sensitive rectification of signals from the magnetizing and measuring coils of the investigated SMM sample and subsequent averaging to find the instantaneous field intensity and magnetic induction of the sample. In the simplest case, this can be done by connecting in series [2] a controlled analog switch and a low-pass filter, i.e., by direct conversion of the measured signal including all its shortcomings, the most important of them being the addition of the errors of all individual units. Here we describe an instrument that measures the coordinates of points for plotting hysteresis loops and is free from many defects of classical ferrometers.The compensating ferrometer (CF) [3] uses a modification of the ferrometric method which is based on the fact that the integral of the derivative of a periodic (period T) odd function, averaged of the period (beginning at the time ti), is equal to the negative instantaneous value of this function at the time ti:

Automatic instrumental platform for the measurement of the characteristics of ferromagnetic materials based on LabVIEW

“…Subsequent averaging is applied to find the instantaneous field intensity and magnetic induction [2]. Krokhin and Sushchev proposed a digital compensating ferrometer that uses a modification of the ferrometric method [3]. With the progress of virtual instrumentation, Pólik and Kuczmann and other research groups developed different computer-controlled measurement systems applying the National Instruments NI-DAC Data Acquisition Card and the National Instruments LabVIEW software package [4].…”