The device forms a closed magnetic

The device forms a closed magnetic circuit and relies on the yoke made of soft magnetic material and the coil bracket to transfer the magnetic force line. the magnetic conductivity of the soft magnetic material determines the performance of the device. improving the magnetic conductivity of yoke and coil support can make more magnetic lines transfer according to the magnetic circuit designed by the device and improve the efficiency of the device; improving the performance of permanent magnet in a certain range can effectively improve the magnetic flux of the coil and can effectively improve the inductive electromotive force at the same vibration frequency. so the choice of magnetic material is very important. In the same volume, the magnetic field intensity of rare earth permanent magnet is the largest, so it is often the first choice for vibration energy devices. At the same time, because of its high coercivity, it will not demagnetize because of the vibration of the equipment. hence, this device selects rare earth permanent magnet material, ndfe35 as permanent magnet material. The coercivity of soft magnetic material is similar to that of permanent magnetic material. the greater the coercivity, the more difficult it is to magnetize the material. The magnetic head and coil bracket of this device play the role of conductive magnetic force line, the transfer direction is constantly changing, so the material with low coercive force should be selected.