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Application of Magnetic Materials in Wireless Charging Technology

Mar. 13, 2020

The main magnetic materials used in wireless chargers are: Neodymium Magnet, NiZn ferrite thin magnetic sheet, MnZn ferrite thin magnetic sheet, flexible ferrite magnetic sheet; various magnetic insulation sheets made of soft ferrite material. As the main component of wireless charging technology, it plays the role of increasing the induced magnetic field and shielding coil interference in wireless charging equipment. Wireless chargers have higher requirements on soft ferrite material performance, product size, and reliability, and the receiving end has higher requirements on them.

According to the placement of the receiving end, the wireless charging transmitting end is divided into a fixed position type, a single coil free position type and a multi-coil free position type. These transmitting ends have different requirements for ferrite products.

Fixed-position chargers use NdFeB permanent magnets for positioning. Terminal equipment needs to be placed in a fixed position to charge and maximize charging efficiency. The Qi standard stipulates that such a design operates at a frequency of 110kHz to 205kHz. Fixed-position chargers have a higher resonance frequency, and generally use NiZn ferrite sheets with low losses and good high-frequency magnetic shielding effects as magnetic isolation sheets.

The coil inside the single-coil free-position type charging device is provided with a driving device and can be moved in a plane. It automatically detects the placement position of the terminal device, and moves the coil to the position, so that the position of the coil is consistent with the receiving position of the terminal. In order to achieve charging and improve charging efficiency, this type of design allows the terminal to be charged anywhere on the charging board. The Qi standard stipulates that the working frequency of this type of charger is 140kHz. Because the coil needs to be moved, and the magnetic isolation sheet is required to have high reliability, the magnetic isolation sheet generally applies a flexible magnetic sheet made by a casting process.

Segment Neodymium Magnet

Segment Neodymium Magnet

The multi-coil free-position type charger can charge multiple terminals at the same time, and a plurality of coils are arranged inside the charger, and these coils cover most of the area of the charging base. Therefore, the terminal can be relatively freely placed on the charging base, and the charger will automatically select several coils that can transmit efficiently to supply power. The Qi standard stipulates that the multi-coil free-position type charger has a working frequency of 105kHz ~ 113kHz, and the magnetic isolation sheet generally uses MnZn power materials with high Bs and low loss characteristics.

Permanent magnet materials used in wireless charging systems, on the one hand, enhance the magnetic flux between the transmitting and receiving coils, and improve transmission efficiency; on the other hand, as a positioning device between transmitting and receiving, it is convenient for terminal equipment to quickly and accurately locate. Small wireless charging equipment mostly uses NdFeB permanent magnet materials; large wireless charging equipment can use permanent ferrite materials instead of NdFeB permanent magnet materials, reducing costs.

The above is the application of the magnetic materials in wireless charging technology introduced by Segment Neodymium Magnet Manufacturer.

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