Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/24—Magnetic cores
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/147—Alloys characterised by their composition
  • H01F1/153—Amorphous metallic alloys, e.g. glassy metals
  • H01F1/15308—Amorphous metallic alloys, e.g. glassy metals based on Fe/Ni
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type
  • H01F17/04—Fixed inductances of the signal type with magnetic core
  • H01F17/06—Fixed inductances of the signal type with magnetic core with core substantially closed in itself, e.g. toroid
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/24—Magnetic cores
  • H01F27/25—Magnetic cores made from strips or ribbons

Definitions

• This invention relates to an amorphous metal magnetic core with a distributed gap for electrical choke applications; and more particularly to a method for annealing the amorphous core to create the distributed gap therein.
• An electrical choke is an energy storage inductor.
• the magnetic flux in the air gap remains the same as in the ferromagnetic core material.
• the permeability of the air ⁇ l
• the gap can be discrete or distributed.
• a distributed gap can be introduced by using ferromagnetic powder held together with nonmagnetic binder or by partially crystallizing an amorphous alloy.
• an electrical choke is made based on heat treating Fe- base amorphous cores.
• the maximum permeability is reduced to between 1/50 and 1/30 of the original value, (for maximum permeability of 40,000 this treatment results in values ranging from about 800 and 1300) and the amorphous cores exhibit a degree of crystallization, which does not exceed 10% of the volume.
• the present invention provides electrical chokes having sizes ranging from about 8 mm to 45 mm OD with permeabilities in the range of 100 to 400 and low core losses (less than 70 W/kg at 100 kHz and 0. IT).
• the magnetic properties are maintained under DC bias (at least 40% of the initial permeability is maintained at a DC bias field of 3980 A m or 50 Oe ).
• the present invention a method for heat treating Fe base amorphous alloys in a controlled way to partially crystallize the bulk of the amorphous ribbon and generate microgaps in the cores. As a result of the distributed gaps, the aforementioned properties are achieved.
• the present invention requires certain annealing temperature and time parameters and degree of control of these parameters in order to achieve the desired choke properties.
• Figure 1 is a graph depicting the relation between the permeability of the core and the annealing temperature, the different curves describing material with different crystallization temperatures
• Figure 2 is a graph depicting the relation between the permeability of the cores and the annealing temperature for different annealing times;
• Figure 3 is a graph depicting the loading configuration of the cores for the annealing in order to achieve temperature uniformity within a few degrees;
• Figure 4 is a graph depicting core loss in W/kg of the cores as a function of the DC bias field and the frequency;
• Figure 5 is a graph depicting the permeability of the cores under DC bias field conditions
• Figure 6 depicts a typical cross-sectional Scanning Electron Microscopy (SEM) picture of the ribbon after the annealing; and Figure 7 describes the permeability as a function of the volume percent of crystallinity.
• SEM Scanning Electron Microscopy
• Fig. 1 depicts the permeability of the annealed Fe-base magnetic core as a function of the annealing temperature.
• the permeability was measured with an induction bridge at 10 kHz frequency , 8-turn jig and 100 mV ac excitation
• the annealing time was kept constant at 6 hrs. All the cores were annealed in an inert gas atmosphere.
• the different curves represent Fe-base alloys with small variations in the chemical composition and consequently small changes in their crystallization temperature.
• the crystallization temperatures were measured by Differential Scanning Calorimetry (DSC).
• DSC Differential Scanning Calorimetry
• Fig. 2 depicts the permeability of the annealed Fe-base cores with the same chemical composition as a function of the annealing temperature.
• the different curves represent different annealing times. The plot indicates that for temperatures higher than 450 °C the effect of the annealing temperature dominates the effect of the annealing time.
• Typical magnetic characterization data for the chokes such as core loss and DC bias are shown in Figs. 4 and 5.
• the core loss data are plotted as a function of the DC bias field and the different curves represent different measuring frequencies.
• the data shown are for cores with 25 mm OD.
• An important parameter forthe choke performance is the percent of the initial permeability that remains when the core is driven by a DC bias field.
• Fig. 5 depicts a typical DC bias curve for a core having 35 mm OD.
• SEM scanning electron microscopy
• XRD XRD
• the volume percent of the crystallization was determined from both the SEM and XRD data and is plotted in Fig. 7 as a function of permeability. For permeabilities in the range of 100 to 400 bulk crystallization in the range of 5 to 30% is required.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Soft Magnetic Materials (AREA)
• Cable Accessories (AREA)
• Suspension Of Electric Lines Or Cables (AREA)
• Manufacturing Cores, Coils, And Magnets (AREA)
• Insulation, Fastening Of Motor, Generator Windings (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=24338791

Family Applications (1)

Country Status (9)

Cited By (4)

Families Citing this family (6)

Family Cites Families (9)

• 1997
  • 1997-01-08 AT AT97901927T patent/ATE215727T1/de active
  • 1997-01-08 KR KR10-1998-0704870A patent/KR100452535B1/ko not_active Expired - Fee Related
  • 1997-01-08 WO PCT/US1997/000178 patent/WO1997025727A1/fr not_active Ceased
  • 1997-01-08 EP EP97901927A patent/EP0873567B1/fr not_active Expired - Lifetime
  • 1997-01-08 CN CN97191661A patent/CN1114217C/zh not_active Expired - Fee Related
  • 1997-01-08 DK DK97901927T patent/DK0873567T3/da active
  • 1997-01-08 JP JP52533897A patent/JP4629165B2/ja not_active Expired - Fee Related
  • 1997-01-08 DE DE69711599T patent/DE69711599T2/de not_active Expired - Lifetime
  • 1997-01-20 TW TW086100556A patent/TW351816B/zh not_active IP Right Cessation
• 2010
  • 2010-09-16 JP JP2010207490A patent/JP4990389B2/ja not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events