The influence of micro-structure on magnetic properties of amorphous powder core was investigated.The results show that the amorphous powders of the powder core become crystallized with the increase of annealing tempe...The influence of micro-structure on magnetic properties of amorphous powder core was investigated.The results show that the amorphous powders of the powder core become crystallized with the increase of annealing temperature,and the permeability decreases from 60 to 12,the core loss increases from 0.2 to 0.3 W·cm^(-3),DC-bias characteristic was improved with further increase of annealing temperature,and the magnetic properties become deteriorated due to decrease of permeability and enhancement of coercive force resulting from the crystallization of amorphous powder.展开更多
The FeSiBC amorphous powder cores were fabricated using powders of the FeSiBC amorphous ribbons which were mechanically crushed for a short time, and the relationship between magnetic properties and powder particle si...The FeSiBC amorphous powder cores were fabricated using powders of the FeSiBC amorphous ribbons which were mechanically crushed for a short time, and the relationship between magnetic properties and powder particle sizes was evaluated. The saturation magnetization Bs of the amorphous Fe82Si2B15C1 alloy was 1.62 T, which provided a superior dc-bias property for the powder cores. Meanwhile, a stable permeability up to high frequency range over 10 MHz and the low core loss of 400 kW/ma at f=50 kHz and Bm =0.1 T were obtained. These excellent high-frequency magnetic properties of the FeSiBC amorphous powder cores could be attributed to the effective electrical insulation between the FeSiBC amorphous powders made by mechanical crushing.展开更多
This paper focus on the Modeling and Calculation of DC current distribution in AC power grid induced under HVDC Ground-Return-Mode. Applying complex image method and boundary element method, a new field-circuit coupli...This paper focus on the Modeling and Calculation of DC current distribution in AC power grid induced under HVDC Ground-Return-Mode. Applying complex image method and boundary element method, a new field-circuit coupling model was set up. Based on the calculation result with complex image method, this paper derived the modification factor for induced earth potential from practical measurement, which increased the accuracy of calculation. The modification method is helpful for evaluation on the effect of means used for blocking the dc-bias current in transformer neutral and also useful for the forecast of the DC current distribution when the power grid is in different line connection mode. The DC distribution character in Guangdong power grid is shown and suggestion is proposed that the mitigation of dc-bias should start from those substations whose earth-potential is highest.展开更多
基金This work was financially supported by Beijing Municipal Science and Technology Program(No.D0405003040121).
文摘The influence of micro-structure on magnetic properties of amorphous powder core was investigated.The results show that the amorphous powders of the powder core become crystallized with the increase of annealing temperature,and the permeability decreases from 60 to 12,the core loss increases from 0.2 to 0.3 W·cm^(-3),DC-bias characteristic was improved with further increase of annealing temperature,and the magnetic properties become deteriorated due to decrease of permeability and enhancement of coercive force resulting from the crystallization of amorphous powder.
基金Item Sponsored by National Natural Science Foundation of China(51071050)
文摘The FeSiBC amorphous powder cores were fabricated using powders of the FeSiBC amorphous ribbons which were mechanically crushed for a short time, and the relationship between magnetic properties and powder particle sizes was evaluated. The saturation magnetization Bs of the amorphous Fe82Si2B15C1 alloy was 1.62 T, which provided a superior dc-bias property for the powder cores. Meanwhile, a stable permeability up to high frequency range over 10 MHz and the low core loss of 400 kW/ma at f=50 kHz and Bm =0.1 T were obtained. These excellent high-frequency magnetic properties of the FeSiBC amorphous powder cores could be attributed to the effective electrical insulation between the FeSiBC amorphous powders made by mechanical crushing.
文摘This paper focus on the Modeling and Calculation of DC current distribution in AC power grid induced under HVDC Ground-Return-Mode. Applying complex image method and boundary element method, a new field-circuit coupling model was set up. Based on the calculation result with complex image method, this paper derived the modification factor for induced earth potential from practical measurement, which increased the accuracy of calculation. The modification method is helpful for evaluation on the effect of means used for blocking the dc-bias current in transformer neutral and also useful for the forecast of the DC current distribution when the power grid is in different line connection mode. The DC distribution character in Guangdong power grid is shown and suggestion is proposed that the mitigation of dc-bias should start from those substations whose earth-potential is highest.
