The iron losses and acoustic noises of a model transformer core made of grain-oriented electrical steel sheets were investigated under DC biased magnetization while altering the amplitude of magnetic flux density,
Bm, and the DC biased magnetic field,
HDC, applied by the third windings. The iron loss increased as
HDC increased up to100 A/m, while over 100 A/m, the increment of iron loss by DC biased field rapidly decreased. The increase in iron loss at the same
HDC was largest at
Bm:1.1−1.5 T. Meanwhile, the acoustic noise increased monotonically as
HDC increased. The acoustic noise of odd-order harmonics was drastically increased under DC biased magnetization, and this is the primary cause of the increase in acoustic noise.
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