A PC based hysteresis loop extractor and its applications

A new, simple and low cost Virtual Instrument (VI) that performs automated extraction of hysteresis loop parameters is presented in this paper. The VI traces the magnetic hysteresis loop of test samples accurately. In conventional loop tracers the area of the loop and iron loss per cycle are computed manually. It is a time consuming process and accuracy is usually low. A new, simple method for automated computation of total area of the loop, retentivity and coercive force using a new VI is presented. Moreover, using the developed instrument, a new single frequency method for separation of iron losses is also presented. A prototype of the loop tracer and VI have been developed and tested. Results were compared with conventional method and found to be accurate. A Mu-metal toroid type core sample was used for the tests. The loop extractor developed has shown to be useful in material testing, selection of material for electromagnetic relays and separation of iron losses by single frequency excitation.