The magnetism is not saturated in the case of no change, the magnetism of the permanent magnetic material is constant, and the soft magnetic material itself is not magnetized, the soft magnetic material is easy to magnetize and easy to demagnetize, when the magnetic flux reaches a certain amount, . Magnetic saturation is a physical property of magnetic materials, which means that the magnetic flux can not be increased indefinitely due to the limitation of the physical structure, so as to maintain the magnetic flux in a certain number of states. Magnetic saturation is a physical property of magnetic materials. Magnetic saturation is harmful in some cases, but in some cases it is sometimes beneficial. For example, magnetic saturation regulator, is to use the core of the magnetic saturation characteristics to achieve the purpose of stabilizing the voltage. Power transformer (coil inductance) appears saturated, the current surge, will soon be fever burned. Hollow coil As the medium within the coil is air, the magnetic reluctance of the air is very large. To make it saturated is very difficult. Although the hollow coil is basically not saturated, not to say that the hollow coil can be infinite use, but said the use of hollow coil bandwidth is very wide.