Kärnförlusterna

Kärnförlusterna is a Swedish term that translates to "core losses" in English. It refers to the energy dissipated within a magnetic material due to its repeated magnetization and demagnetization cycles when subjected to an alternating magnetic field. This energy loss manifests as heat. These losses are a crucial consideration in the design and efficiency of electrical devices that utilize magnetic cores, such as transformers, inductors, and electric motors.

There are two primary components that contribute to kärnförlusterna: hysteresis losses and eddy current losses. Hysteresis losses occur because the magnetic domains within the material do not perfectly reorient themselves with each passing magnetic cycle. This requires energy input to overcome the internal friction of the domain movements. Eddy current losses, on the other hand, arise from induced electrical currents that circulate within the conductive core material itself. These currents are generated by the changing magnetic flux and dissipate energy as heat due to the resistance of the core.

The magnitude of kärnförlusterna is influenced by several factors, including the properties of the magnetic material (such as its B-H curve and resistivity), the frequency of the alternating magnetic field, and the magnetic flux density. Materials with lower hysteresis loss and higher resistivity are preferred for applications where minimizing energy dissipation is important. Laminating the core, which involves stacking thin sheets of magnetic material insulated from each other, is a common technique to reduce eddy current losses, as it breaks up the paths for these circulating currents.