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Magnetic moment is an important parameter that describes the magnetic strength of ferromagnetic materials, especially permanent magnet materials. Open circuit magnetic moment is one of the qualified indicators for finished permanent magnets. The pulling method is widely used in the domestic permanent magnet industry to measure magnetic moment. Another important purpose of using this method to measure magnetic moment is to sample and inspect the uniformity of large permanent magnets. This test is generally required for permanent magnets used in wind power generation and electric vehicles. China has established the standard GB3217-2013 for measuring the magnetic properties of closed magnetic circuits in permanent magnet materials, but there is no relevant method standard for measuring the open circuit magnetic moment that is applicable to the above requirements. Currently, the international standard is IEC60404-14 (pulling or rotating method for testing the magnetic dipole moment of ferromagnetic materials), and China is also developing similar standards.
By measuring the open circuit sample in a Helmholtz coil with a strictly calibrated coil constant of k, the magnetic flux value can be obtained, and the magnetic moment M of the material can be calculated based on the magnetic flux value.
The calculation formula for measuring the magnetic moment of a magnet using a magnetometer and a Helmholtz coil is as follows:
M=k* Ф, among
M represents the magnetic moment of the magnet, in units of Wb · cm-1
K represents the coil constant, in cm-1 (a change in the unit of coil constant can cause a change in the unit of magnetic moment)
Ф Represents magnetic flux value, unit: Wb
