Papers by Author: Jian Yong Lou

Abstract: It is the tendency to adopt novel soft magnetic materials in planar magnetic components to have much more attractive features. In this paper, the nanocrystal magnetic strip is used to consist of magnetic core of planar inductor. A novel network model for dynamic stray capacitances of planar inductor with matrix structure is presented. The magnetic core is taken into account to be one part of the equivalent circuit of planar inductor in high frequency, and its electric potential is considered to be suspended. To analyze the dynamic stray capacitance accurately, the 3D FEM model is adopted, and the parameters for dynamic stray capacitance of inductor windings are obtained. By equivalent circuit simulation of planar inductor, the impedance feature of planar inductor is obtained. The test results by impedance analyzer verify the dynamic capacitance network model.

Abstract: C/C-SiC composites were rapidly fabricated by a two-steps processing. Firstly a short-cut carbon fiber felt (SC) and a 2D carbon fiber felt (2D) were densified to C/C composites by a thermal gradient chemical vapor infiltration (CVI) method with vaporized kerosene as a precursor in 2h, 3h, 4h and 5h, respectively. Then the C/C composites were infiltrated and reacted with melting silicon to obtain C/C-SiC composites. The results show that, with increase of the CVI time, the densities of the two types of C/C-SiC composites decrease in the range of 2.28g/cm3 to 2.00g/cm3; their porosities increase ranging from 1.3% to 7.5%; the contents of the β-SiC and the unreacted Si phases in the composites decline. The flexural strength of the 2D_C/C-SiC composite is much higher than that of the SC_C/C-SiC composite when prepared in the same condition.

Abstract: The novel soft magnetic materials and magnetic core structure used in planar transformer have been studied. The frequency, electrical and structure feature of the planar transformer with matrix structure was described. Then the novel magnetic materials used in the planar transformer were discussed, which were very different from ferrite block. The silicon steel strip was first represented, the magnetic characteristic of which was related to its geometric dimension, working frequency and the component. The microcrystallite alloy and amorphous alloy magnetic materials were then indicated, including iron-base nanocrystal and cobalt-base amorphous alloy. The magnetic materials of the above amorphous alloy and microcrystallite alloy were compared respectively. These soft magnetic materials could be used as the magnetic core in planar transformer, and the magnetic core could be composed of thin strip and line. The structure of magnetic core was flexible, which could benefit the planar transformer to reduce its volume. The development and trendy of novel magnetic materials and magnetic core in planar transformer were analyzed and discussed in this paper.