Project name: Eddy current losses in open core of transformer
Project acronym: GOJTRA
Dates: December 2020 - November 2024
Budget: 683.000,00 HRK
Funding: Croatian Science Foundation (HRZZ)
Project number: TBA

Power voltage transformers (combination of instrument and power transformer) are an expanding product niche, both for auxiliary power and rural electrification applications. Unique Croatian concept of such transformers with open core is already successful in global market.  Continuous improving of procedures for design and construction of open cores is necessary for further market success. Losses in the core are fundamental parameter in design and eddy current losses are particularly important. Calculation of these losses in closed cores built of magnetic laminations has been researched and developed for many years. Most frequently, induced currents and losses are determined based on calculated distribution of magnetic flux. Results of these researches cannot be applied to open cores because of adverse ratio of dimensions (thickness of lamination is less than one millimeter; width of the core is several centimeters and height is a few meters) and extremely inhomogeneous distribution of the magnetic flux density at open ends of the core. Necessary data for calculation of losses are magnetic characteristics of material. They are extremely nonlinear and   their accession in acceptable precision is very limited. Aims of this research are:

• development of theoretical basis for numerical computation of magnetic flux density distribution and eddy currents in open cores;
• creation of computation algorithms and programming of package for computation of eddy currents and losses in open core of power voltage transformer
• verification of calculation results by comparison to measurements on models of cores in the firm Končar – Instrument transformers
• development of automated system for measuring of nonlinear magnetic characteristics of ferromagnetic materials in high precision.