Fyzikální ústav Akademie věd ČR

On October 18th, 2012, the Grant Agency of the Czech Republic Prize was awarded to Dr. Oleksandr Stupakov from the Institute of Physics of the Academy of Sciences of the Czech Republic for the individual postdoctoral project "Development of a new system for measurement of open-circuit ferromagnetic samples with controlled magnetization waveform".

Despite a long history of magnetic investigations, there is still no widely-accepted “universal” technique, stable and user-friendly, for measurement of magnetically open samples, e.g. a usual peace of ferromagnetic steel. The project was focused on the measurements of the magnetically soft electrical steels, which are used as the cores of transformers, generators and motors. Therefore, these steels are practically the sole type of commercially produced materials whose magnetic hysteresis properties are the main technological parameters of importance.

Olexandr Stupakov

There are two international standards used for laboratory measurements of electrical steel sheets. They are accurate but have serious drawbacks; notably, they are expensive and time consuming. For example, an outdated Epstein frame, which has been used for more than a century, needs a pseudo-closed square arrangement of steel strips. The cumbersome closed constructions of both standard instruments allow to calculate the sample magnetic field to be simply proportional to the current in the magnetization windings.

Currently, digital measurement techniques and modern magnetic field sensors afford the opportunity to examine this old problem from a different standpoint. The physical idea is to control the magnetic induction waveform using a digital feedback procedure and to measure the magnetic field directly and precisely. This was experimentally proved to provide repeatable and reliable results, even in the case of small magnetically open samples. These results are believed to stimulate the revision of the main principles of magnetic quality testing of the ferromagnetic structural materials in laboratories and in industrial practice.