Sintered NdFeB permanent magnet is mainly used in the manufacture of direct drive permanent magnet or semi direct drive wind power generator, the use of high performance NdFeB, which makes the wind power generator has the advantages of light weight, more convenient repair, high efficiency. Direct drive wind power generator is the development trend of the future of the wind turbine permanent magnet. According to the forecast of the state authority: in 2020 China's wind power installed capacity will exceed 1 million million, accounting for more than 10% of the weight of the national electric power installed. Therefore, sintered NdFeB magnets in wind power industry.
The wind power generator field in the sea, air, working condition is very poor, so the magnet requirements are also a lot of.
1, high remanence: principle of wind generator is blade using wind driven, driven by a rotor permanent magnet array contains in the stator winding (conductor) electromagnetic induction effect caused by electric power. The magnetic flux density in the winding generates induction electromotive force is proportional to the permanent magnet array in the air gap generated (magnetic induction intensity) Bg, square root, and the maximum energy of Bg is proportional to the product of the permanent magnet so that high energy materials is the product of one of the pursuit of the parameters of generator.
2, high coercive force: wind turbine operation, demagnetization of permanent magnet magnetic field generated by the experience of reverse winding of the alternating, so the requirements of permanent magnet wind power generator has enough coercivity, to resist the strong reverse demagnetizing field effect.
3, high working temperature: wind power generator to work at 40 degrees below zero on the 120 degree range, requirement of magnet in the working temperature range by irreversible loss is low, in order to guarantee the normal work of wind power generator.
4, the other physical properties: a) corrosion resistance: the changes of wind power generator of the atmospheric environment is great. In some places in the sea not only moist and wet; soil salinity; sometimes the atmosphere may contain some alkali or acid. These will have a certain corrosive action on the magnet, thereby reducing the magnetic, serious and even completely destroyed the magnet. In order to ensure the normal operation of wind turbines in the next 20 years, the requirements of magnet in 20 years not to generate the magnetic significantly reduce. Magnetic reducing factor is one of the magnets may appear various corrosion. Therefore, the magnet requires a high resistance to corrosion, and corrosion protection appropriate surface treatment. B) impact: wind power generator in the operation process, the inevitable emergence of shock, especially in the strong wind, the motor itself has a strong vibration, magnet magnet and magnetic requirements keep intact in long-term vibration under the stable. C) thermal conductivity: wind turbine during operation, due to eddy current metal magnetic material, will make the magnet heating and warming. In order to reduce the temperature of magnet, should let the coefficient of thermal conductivity of magnet material as high as possible (to reduce eddy current is mainly rely on to reduce the surface resistance) |
