永磁体预偏磁功率电感永磁结构分析

磁元件在各种功率变换器中一直有着不可替代的作用，如电感在电路中起到储能、滤波等作用，并且其体积占据的比重也较大，因此磁元件的优化设计备受关注，永磁体偏磁技术的出现为其开辟了一条新的途径。永磁体偏磁技术不仅可以提高磁元件的抗饱和能力，也有助于减小磁元件的体积。针对现有偏磁方案的不足，以Boost电感为例，建立电感的磁路模型进行分析，得到电感各个磁路上的参数设计要求，防止磁芯退磁，提高电感元件工作的稳定性，最终设计出新型的偏磁方案模型。对比几种优化结构，采用钕铁硼作为永磁体材料，用高饱和磁密的磁芯材料把永磁体和电感磁芯隔离开，避免局部饱和，并且当支路磁芯体积较大、永磁体夹在两个支路磁芯中间时，该结构的效果较好。同时还对引入短路环进行损耗分析。当下功率变换器不断朝着轻量化、小型化、高功率密度化方向发展，永磁体预偏磁技术为其增加了更多的可能性。

Analysis of Permanent Magnet Structure of Permanent Magnet Bias Power Inductor

Magnetic components always play an irreplaceable role in many kinds of power converters, for example, inductors can store energy and filter waves in the circuit while their volumes occupy a larger proportion. Therefore, the optimization and design of magnetic components has caught much attention. The emergence of permanent magnet bias technology has opened up a route, which can not only improve the anti-saturation capability of magnetic components but also reduce their volumes. In consideration of the shortcomings of the existing biasing scheme, a Boost inductor is taken as an example, and its magnetic circuit model is built. To avoid the demagnetization of magnetic core and improve the stability of inductor components, the design requirements for parameters of each magnetic circuit are derived. At last, a novel model of the biasing scheme is designed. Several optimization structures are compared. NdFeB is used as permanent magnet material, and the permanent magnet and core are isolated by a high-saturation magnetic flux material to avoid local saturation; moreover, when the branch core has a larger volume and the permanent magnet is sandwiched between two branch cores, this structure has a better effect. Meanwhile, loss analysis is performed after the addition of a short-circuit ring. Since the power converters are continuously developing towards lightweight, miniaturization, and high-power density, the permanent magnet bias technology raises more possibilities of their development.