Method for estimating noise of soft magnetic core

A method for estimating a noise of a soft magnetic core, comprising:

• acquiring a soft magnetic core, wherein an excitation coil is wound around the soft magnetic core;
• measuring an impedance value of the excitation coil under a natural geomagnetic field by frequency sweeping, and determining a peak frequency point when the impedance value reaches a peak;
• measuring, under different direct current bias magnetic fields, an inductance value and a resistance value of the excitation coil at the peak frequency point along an axial direction of the soft magnetic core to respectively obtain an unsaturated inductance value and a resistance peak value of the soft magnetic core;
• and
• obtaining an equivalent noise of the soft magnetic core based on the unsaturated inductance value and the resistance peak value,
• wherein the method further comprises:
• measuring a direct current resistance of the excitation coil, and determining a noise power spectral density of the excitation coil based on the direct current resistance and the resistance peak value, and
• calculating a conversion coefficient between an induced voltage of the excitation coil and an external magnetic field based on the unsaturated inductance value by:
• FS=−j2πf×K1×Lp
• wherein FS represents the conversion coefficient, f represents the peak frequency point, K1 represents a first constant, and Lp represents the unsaturated inductance value,
• wherein the equivalent noise of the soft magnetic core is obtained based on the unsaturated inductance value and the resistance peak value by:
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• wherein Vnoise represents the noise power spectral density, K2 represents a second constant, Rind represents the resistance peak value, and Rg represents the direct current resistance of the excitation coil.