Electric motors are electromechanical products that involve the conversion of various forms of energy, such as electrical energy, magnetic energy, and mechanical energy. In these energy conversion processes, the magnetic field is a very critical factor, and the strength and saturation of the magnetic field have a significant impact on the performance of the motor.

Transformers and motors both use ferromagnetic materials to shape and guide magnetic fields. Magnetic fields are the medium for energy transfer or conversion. In addition to electromagnetic windings, permanent magnet materials are also widely used in motors.

For asynchronous motors, in addition to serving as armature windings, a very important function of the stator windings is excitation; the iron core is a typical magnetic material and serves as the medium for the motor's magnetic field, the strength of which is directly related to the magnitude of the current.

Ferromagnetic materials acquire magnetism because they contain countless magnetic domains. In the absence of an external magnetic field, the magnetic fields of these domains cancel each other out, and the ferromagnetic material is non-magnetic. When an external magnetic field is applied, such as when the stator winding of an asynchronous motor is energized, an external magnetic field is generated. The countless magnetic domains within the core material, under the influence of this field, unify their orientation, thus exhibiting magnetism. The stronger the external magnetic field, the more domains within the material unify their orientation, resulting in stronger magnetization and a stronger magnetic field. However, when the strength of the external magnetic field increases to a certain point, the magnetization of the material no longer increases because the internal magnetic domains are essentially aligned. Increasing the external magnetic field will not enhance the magnetism of the material. At this point, the material is said to have reached saturation magnetization, and its magnetism has reached a saturated state.

In motor products, the effective matching of the iron core and the current has a significant impact on the motor performance, as well as on the motor's temperature rise, electromagnetic vibration, and noise.

In actual production and processing, when the effective iron length of the motor core is insufficient due to factors such as loose stacking, stator-rotor misalignment, or core horseshoe-shaped defects, the most direct consequence is an increase in the motor's no-load current and a rise in motor temperature. In the actual design and application of motors, when the actual voltage exceeds the rated voltage, the motor will also reach magnetic saturation, resulting in significant heat generation.