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众所周知,电机是以磁场为媒介进行电能与机械能相互转换的电力机械。磁场可以由电流励磁产生,也可以由永磁体产生。但一般的永磁体,由于磁能密度低,因而所建立的能量交换所必需的气隙磁场强度也较低,所以只能制造容量小的永磁电机,如目前大量生产的铁氧体永磁电机。高性能稀土永磁材料,特别是钕铁硼问世后,情况发生了重大变化。高性能钕铁硼磁体产生的磁场,不仅可以达到电流励磁所产生的磁场要求,而且还远远超过电流励磁,因而可以制造出数千kW的大中型电机。
As we all know, the motor is a magnetic field as a medium of electrical energy and mechanical energy conversion between the electrical machinery. The magnetic field can be generated by current excitation, can also be generated by a permanent magnet. However, due to the low magnetic energy density, the conventional permanent magnets have a low air gap magnetic field strength required for energy exchange, so only permanent magnet motors with small capacity can be manufactured. For example, currently mass-produced ferrite permanent magnet motors . High-performance rare earth permanent magnet materials, especially the advent of NdFeB, the situation has undergone major changes. The magnetic field generated by the high-performance NdFeB magnets can not only achieve the magnetic field generated by current excitation, but also far exceed the current excitation, which can produce large and medium-sized motors of several thousands of kW.