Hysteresis losses
The energy dissipated at each magnetisation cycle of the core.
Definition
Hysteresis losses correspond to the energy spent re-magnetising the core at each alternation of the current. The magnetic material resists having its magnetisation reversed: this “lag” between the applied field and the resulting magnetisation traces a cycle (the hysteresis loop) whose area represents the energy lost per cycle.
At 50 Hz, this cycle repeats 50 times per second, hence a continuous dissipation of heat in the core. Together with eddy currents, hysteresis forms the iron losses. It depends on the material: “soft” magnetic steels, with a narrow hysteresis loop, are chosen precisely to minimise these losses.
It increases with frequency and with the working flux density.
The ABL tip
Choosing a low-hysteresis magnetic steel (grain-oriented sheets) reduces these losses and the heating. ABL Transfo selects the steel grade according to your efficiency and temperature targets.
