Using a magnetic field to transmit power can realize the convenience of wireless charge, and this wireless charge technology has made great progress in recent years. However, for a long time, there has been a problem that the thickness of the material can not be effectively reduced because the thickness of the material is positively related to the transmission power, that is to say, if the transmission power is required to be high, the thickness of the material must be increased. We know that the space inside the mobile phone has high value. Thickening materials is to occupy a larger volume, which is just fatal for the mobile phone designer.
In order to solve this problem, it is an effective solution to develop magnetic materials with larger saturation magnetization.
Different materials affect the inductance and transmission power of the coil. If we want to realize the wireless charging module that takes into account the characteristics of thin type and high transmission power, the characteristics of related materials should be higher, such as permeability and saturation. "However, the performance of these material properties is usually the opposite, that is, the lower the permeability, the higher the saturation." An ideal magnetic material must have a high permeability, that is to say, as long as a magnetic field is added, it will produce thousands of times of magnetic flux.
However, the magnetic flux has its saturation limit. After reaching the saturation point, no matter how much magnetic field is added, the magnetic flux can not be increased. The trade-off between permeability and flux saturation is an important consideration when manufacturers choose wireless charge materials. Therefore, it is necessary to optimize the material in the aspects of material simulation selection, formulation design, crystal structure and process control, so we should improve the saturation as much as possible while maintaining a certain permeability.
At present, the main magnetic materials used in a wireless charger are: NdFeB permanent magnet, NiZn ferrite thin magnetic sheet, MnZn ferrite thin magnetic sheet, flexible ferrite magnetic sheet; various magnetic separators made of soft ferrite materials are the main components of wireless charging technology, which play the role of increasing the induced magnetic field and shielding coil interference in wireless charging equipment. The magnetic wireless charger has higher requirements on the performance of soft ferrite material, product size and reliability, and the receiving end has higher requirements on it.
According to the way of receiver placement, the wireless charge transmitter can be divided into fixed position type, single-coil free position type and multi-coil free position type. The requirements of these transmitters for ferrite products are different.