±1% Tolerance Permanent Neodymium Ring Magnet for Machine at Competitive

Neodymium Generator Permanent Ring Magnet for Machine

NdFeB permanent magnet is called the third generation rare earth permanent magnet and is the most permanent magnetic material with the highest magnetic properties. The main phase of the sintered NdFeB alloy is the intermetallic compound Nd2Fe14B, which has a saturation magnetic polarization (Js) of 1.6T<1>. Since the sintered NdFeB permanent magnet alloy is composed of the main phase Nd2Fe14B and the grain boundary phase, and the grain orientation of Nd2Fe14B is limited by the process conditions, the remanence of the magnet can reach 1.5T. The German vacuum melting company (Vacuumschmelze GmbH) produced a neodymium iron boron magnet with a maximum magnetic energy product (BH) max of 57 MGOe. Domestic NdFeB manufacturers can produce N50 grade magnets with a maximum magnetic energy product of 53MGOe. Increasing the alloy master ratio, increasing the degree of grain orientation and the density of the magnet, the maximum magnetic energy product of the magnet can be increased; but the theoretical value of the maximum magnetic energy product of the single crystal Nd2Fe14B is not more than 64 MGOe<1>.

The demagnetization curve of NdFeB at room temperature is similar to a straight line. Therefore, when designing a permanent magnet motor, it is often preferred to select a high-grade NdFeB (ie, the material (BH)max is high) to obtain a high air gap magnetic density. When the motor is running, due to the existence of the alternating demagnetizing field and the sudden change of the load, the demagnetizing field generated by the instantaneous large current requires the selection of neodymium iron boron magnetic steel with a sufficiently high coercive force.

The addition of an element such as ruthenium o the alloy increases the intrinsic coercive force (jHc) of the NdFeB, but the remanence (Br) of the magnet decreases. Therefore, the high-performance NdFeB magnet for wind turbines takes into account its coercivity and remanence.