Commercial Inductors Research Articles

Novel FePBNbCr glassy alloys “ SENNTIX” with good soft-magnetic properties for high efficiency commercial inductor cores

According to a recent study, Fe-based glassy alloys are expected good soft-magnetic properties such as high saturation magnetization and lower coercive force. We focused on Fe-based glassy alloys and have succeeded in developing novel glassy Fe 97− x− y P x B y Nb 2Cr 1 ( x = 5–13, y = 7–15) alloys for an inductor material. The glassy alloy series of Fe 97− x− y P x B y Nb 2Cr 1 ( x = 5–13, y = 7–15) have high glass-forming ability with the large critical thickness of 110–150 μm and high B s of 1.25–1.35 T. The glassy alloy powder with chemical composition Fe 77P 10.5B 9.5Nb 2Cr 1 exhibits an excellent spherical particle shape related to the lower melting point and liquid phase point. In addition, Fe–P–B–Nb–Cr powder/resin composite core has much lower core loss of 653–881 kW/m 3, which is approximately 1/3 lower than the conventional amorphous Fe–Si–B–Cr powder/resin composite core and 1/4 lower than the conventional crystalline Fe–Si–Cr powder/resin composite core due to the lower coercive force of 2.5–3.1 A/m. Based on above results, the glassy Fe 77P 10.5B 9.5Nb 2Cr 1 alloy powder enable to achieve ultra-high efficient and high quality products in a commercial inductor. In fact, the surface mounted inductor using Fe–P–B–Nb–Cr powder/resin exhibits the high efficiency of approximately 2.0% compared with the conventional inductors made of the crystalline Fe–Si–Cr powder/resin composite core.

FePBNbCr Soft Magnetic Glassy Alloys <i>“SENNTIX”</i> with Low Loss Characteristics for Commercial Inductor Cores

The inductor for a power supply is expected to have higher efficiency and capability of dealing satisfactorily with large current. Additionally, high corrosion resistance characteristics are also required for commercial inductors in practical use of. Thereby, we focused on Fe-based glassy metal alloys with both high magnetization and low magnetic anisotropy ［1］, and developed the novel glassy metal alloys with a chemical composition Fe97-x-yPxByNb2Cr1. In this glassy metal alloy, 1 at % Cr is the optimum composition for the realization of higher corrosion resistance as well as a high magnetic flux density. The glassy Fe97-x-yPxByNb2Cr1 (x=5-13, y=7-15) alloy exhibits the high glass-forming ability leading to the large thickness of 110-150 μm and low coercive force of 2.5-3.1 A/m due to higher structural homogeneity in wide range of composition. The large critical thickness of this alloy should be caused by the high glass-forming ability (GFA) due to the existence of the super cooled liquid region (Tx) of roughly 30 K. Therefore a Fe77P7B13Nb2Cr1 powder/resin composite core displays a much lower core loss of 650 W/m3 than the conventional amorphous Fe75Si10B12Cr3 powder/resin composite core by approximately 1/3.

Internal Geometry Variation of LTCC Inductors to Improve Light-Load Efficiency of DC-DC Converters

A low-profile power inductor fabricated using low-temperature cofired ceramic (LTCC) technology has been demonstrated to improve the light-load efficiency of a converter, without the use of additional control circuitry. This is brought about by the material and the geometry, which causes a change in inductance with load current. Variation in inductor geometry is performed experimentally to study the effects on the light-load efficiency of a converter. By decreasing the conductor width of the inductor, the light-load efficiency can be further improved by 30% in comparison with using commercial inductors of similar inductance. Sufficient core thickness is necessary to have sufficient inductance, since an inductance value which is too low is detrimental from the system power loss point of view, as demonstrated experimentally. From the circuit point of view, there seems to be a critical inductance value, whereby increasing the inductance further, does not result in significant improvement in power stage efficiency. Changing conductor thickness in the range of 260 to 550 mum does not result in significant improvement in the overall efficiency of the converter. Variation in the number of parallel conductors in a multiconductor structure does not have significant effect on light-load efficiency improvement.

On-chip matching networks for radio-frequency single-electron transistors

In this letter, the authors describe operation of a radio-frequency superconducting single electron transistor (rf-SSET) with an on-chip superconducting LC matching network consisting of a spiral inductor L and its capacitance to ground Cp. The superconducting network has a lower Cp and gives a better matching for the rf-SSET than does a commercial chip inductor. Moreover, the superconducting network has negligibly low dissipation, leading to sensitive response to changes in the rf-SSET impedance. The charge sensitivity δq=2.4×10−6e∕Hz in the subgap region and energy sensitivity δε=1.9ℏ indicate that the rf-SSET is operating in the vicinity of the shot noise limit.

Multielement magnetic probe using commercial chip inductors

A 60-element magnetic probe array has been constructed using miniature commercial chip inductors. The array consists of twenty clusters of three coils each mounted on a linear fixture. The coils are oriented in orthogonal directions to yield three-dimensional information. The array has been used to investigate magnetic properties of spheromaks.