KR20030028990A - Soft magnetic core for power factor correction inductors manufactured with permalloy alloy powder - Google Patents

Abstract

PURPOSE: A soft magnetic core is provided to achieve excellent DC superposition characteristics, while reducing total resistance and magnetic core loss. CONSTITUTION: A soft magnetic core contains molybdenum 2 to 4 weight%, nickel 38 to 48 weight% and ferrum. The nickel is dissolved at the temperature of 1650 to 1700 Deg.C for 1 or more hours, and ferrum-molybdenum alloy is added to the resultant structure and dissolved at the temperature of 1700 to 1800 Deg.c. Subsequently, ferrum is added and dissolve.

Description

SOFT MAGNETIC CORE FOR POWER FACTOR CORRECTION INDUCTORS MANUFACTURED WITH PERMALLOY ALLOY POWDER}

The present invention relates to a soft magnetic core for a power factor improving inductor manufactured from a PERMALLOY alloy powder, and more particularly, a permalloy alloy having excellent DC overlapping characteristics and low total resistance, excellent temperature stability, and low noise. A soft magnetic core for a power factor improving inductor made of powder.

In general, soft magnetic cores used as inductors for power factor improvement are manufactured from silicon steel sheets or amorphous alloys.In the case of silicon steel cores using silicon steel sheets, multiple layers of rolled silicon steel sheets are laminated. In the case of amorphous core using an amorphous alloy, a ribbon was manufactured by quenching and solidifying a ribbon, and then laminated in multiple layers to form a toroidal core and an air gap was formed. It was.

The main characteristics required for cores used in power factor improving inductors are excellent DC overlapping characteristics, low core loss, low noise and vibration, and low heat generation.

The DC superposition characteristic is a characteristic of magnetic core for the lameness in which DC is superimposed on the weak AC generated in the process of converting AC input into DC in the power supply device. The magnetic permeability is lowered. At this time, the DC superposition characteristic is evaluated as a ratio expressed by the magnetic permeability without overlapping DC to the magnetic permeability at the time of DC overlap, and the high value shows the excellent characteristic.

However, the core made of the silicon steel sheet has a disadvantage that the core loss is relatively large and thus overheats during operation, and the permeability is greatly decreased at high frequencies. On the other hand, amorphous cores have a larger air gap compared to metal powder soft magnetic cores, resulting in a large leakage flux, a large variation in inductance depending on the length of the air gap, poor temperature stability, and relatively high noise. In addition, when the high DC current overlaps, there is a problem that the permeability is greatly reduced.

In order to solve the above problems, the present invention by using the core material used as a conventional power factor improving inductor made of powder of an alloy having excellent DC overlapping characteristics, excellent DC overlapping characteristics and low total resistance, It is an object of the present invention to provide a soft magnetic core for a power factor improving inductor made of a permalloy alloy powder having better temperature stability and less noise than an amorphous core.

1 is a process flow diagram illustrating a process for manufacturing a soft magnetic core for a power factor improving inductor made of a permalloy alloy powder according to the present invention;

Figure 2 is a graph showing the change in inductance according to the DC current of the soft magnetic core for power factor improving inductor and conventional amorphous core made of permalloy alloy powder according to the present invention.

In order to achieve the above object, the present invention is a permalloy alloy powder, characterized in that as a weight%, molybdenum (Mo) 2-4%, nickel (Ni) 38-48% and the residual amount is made of iron (Fe) To provide a soft magnetic core for the power factor improving inductor manufactured.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

1 is a process flow diagram showing a manufacturing process of a soft magnetic core for a power factor improving inductor made of a permalloy alloy powder according to the present invention.

As shown in Figure 1, in the present invention, the alloy melt is preferably prepared by dissolving Ni first, followed by dissolution by adding Fe-Mo alloy, and then dissolution by adding Fe to have a final powder alloy composition. Do.

At this time, the addition amount of Ni, Fe-Mo alloy and Fe is composed of an alloy composed of Fe: 2 to 4%, Ni: 38 to 48%, and the remainder with inevitable impurities and Fe as the final powder alloy composition by weight. Control to lose.

At this time, in the case of dissolving Ni, it is preferable to select a melting temperature of 1650 to 1700 ° C. The reason for this is that when the melting temperature is 1650 ° C or less, the melting of Ni is not sufficiently performed, and when the melting temperature is 1700 ° C or more, the molten metal is oxidized Because there is a fear.

In addition, it is preferable to select a dissolution time of at least 1 hour for sufficient dissolution. The dissolution temperature is preferably set at 1700-1800 ° C. when Fe-Mo alloy is added to and dissolved in the molten Ni molten metal. The reason is that, as in the melting of Ni, sufficient dissolution is not performed below 1700 ° C., when the melting temperature is higher than 1800 ° C., the molten metal is oxidized and it is uneconomical. At this time, the dissolution time is preferably selected to 1 hour or more for sufficient dissolution.

As the Fe-Mo alloy, any conventional Fe-Mo alloy can be used, but an alloy of 40% Fe-60% Mo is preferably used. In addition, when Fe is added and dissolved in Ni molten metal, the temperature is preferably selected to be the same as the melting temperature of the Fe-Mo alloy.

The Fe-Mo alloy and Fe were added to and dissolved in the Ni molten metal, followed by an alloying treatment performed by heating the molten Ni, Fe-Mo alloy and Fe dissolved at 1750 to 1800 ° C. and maintaining at this temperature for at least 1 hour. The reason is that when the alloying temperature is 1750 ° C. or less, the diffusion rate of atoms is low, so that the alloying time is long and the fluidity is difficult to powder, and when the temperature is 1800 ° C. or higher, the melt is evaporated. This is because oxidation of the molten metal is concerned.

The alloying treatment time is preferably selected to at least 1 hour in order to achieve sufficient alloying, and the higher the purity of the Ni and Fe-Mo alloys, the better, and preferably an alloy having a purity of 99.9% or more. I use it.

Powder is prepared by injecting a fluid into the alloyed melt as described above. That is, the melt is powdered by quenching by injecting a fluid into the melt stream. In this case, an inert gas such as argon (Ar) gas or nitrogen (N 2) gas and water may be used as the fluid to be supplied. The spraying conditions of the fluid are selected in consideration of the particle size of the powder, the form of the powder and the atomic arrangement of the powder, and may be changed according to the type of the fluid.

In case of using an inert gas such as Ar gas or N2 gas as the fluid to be injected, the powder has a spherical shape, and when water is used as the fluid to be injected, it has a regular polygonal shape. In the case of fluid injection, when the fluid is an inert gas such as Ar gas or N2 gas, the injection pressure is preferably 50 to 1200 psi and the flow rate is 1 to 14 m ³ / min, and when the fluid is water, the injection pressure is 800 to The flow rate is preferably selected to be 110 to 380 L / min at 3000 psi.

When the injection pressure is less than the above, the particle size of the powder becomes large, the shape of the particles becomes irregular, and when the particle size is larger than the above injection pressure, all have a spherical shape, but the powder particle size is too small. It is preferable to select.

On the other hand, if the injection flow rate of the fluid is too small, it is difficult to quench the melt sufficiently to obtain an irregular Disorder State, and if it is too large, uniform powdering of the melt is not achieved. It is preferable to select in the above range.

N2 gas used for powdering the melt is preferably used by vaporizing a liquefied gas, and water may be used at 25 ° C. In this way, by appropriately selecting the fluid injection conditions, that is, the injection pressure and the injection flow rate during the injection of the fluid it is possible to produce a powder having a particle size range, spherical or regular polygonal shape and irregular atomic arrangement state.

Preferred powder particle size distributions used in the present invention are 5 to 25% by weight of -100 to +230 mesh (60 to 149 μm), 25 to 45% by weight of -230 to +325 mesh (45 to 60 μm) and -325 mesh (45 micrometers or less) The passing content has 45 to 65 weight%.

In order to use the powder prepared as described above for the alloy powder soft magnetic core for the power factor improving inductor, the content of carbon (C) in the powder is preferably limited to 100 ppm or less, and oxygen (O) content to 200 ppm or less.

Therefore, when the content of carbon and oxygen in the powder exceeds the above range, the powder should be reduced in a reducing atmosphere such as a hydrogen atmosphere (Hydrogen Atmosphere), and the reduction treatment is performed at a temperature range of 700 to 800 ° C. It is preferable to carry out for more than time.

Insulation coating is performed by adding 0.5 to 3.0% by weight of a mixed ceramic to the alloy powder prepared as described above. The mixed ceramic is mixed in water glass (Sodium Silicate) and an aqueous solution based on talc and kaolin. Mixture.

The powder coated as described above is molded into a desired core shape, and more preferably, the powder is molded at a molding pressure of about 240,000 psi using a press in a core mold. At this time, in order to reduce the friction between the powder and the powder or between the molded body and the mold, it is preferable to mix zinc stearic acid (Zn-Stearate) with the powder 1% or less before molding.

Next, after annealing the core shaped as described above, the magnetic properties are checked, and then an alloy powder for power factor improvement inductor is coated by coating polyester or epoxy resin on the core surface to protect core properties from moisture and air. Soft magnetic cores are prepared. At this time, the thickness of the epoxy resin coating layer is preferably about 50 ~ 200㎛.

In addition, the annealing treatment is performed to remove stresses and deformations remaining in the molded body, and the annealing conditions are controlled in this respect, and more preferably, a temperature of 530 to 740 ° C. under a reducing atmosphere such as a hydrogen atmosphere. It is preferable to perform about 30 to 90 minutes.

Hereinafter, the present invention will be described in detail through examples.

EXAMPLE

Ni, which has a purity of 99.9%, was charged into a high frequency induction furnace, heated to 1650 ° C, dissolved, and then heated to 1700 ° C to add Fe (40%)-Mo (60%) alloy, and maintained for 1 hour and 10 minutes. After dissolving, after dissolving by adding Fe having a purity of 99.9%, the temperature was raised to 1800 ° C. and maintained for 1 hour to prepare a melt to have a composition as shown in Table 1 below.

Then, while freely dropping the melt to the lower portion of the strip of the melt N2 gas at -183 ℃ to the injection pressure of 90psi and a flow rate of 9m ³ / min to prepare a powder, and the powder is ceramic coated And 0.5% by weight of zinc stearic acid were added and mixed to form a cyclic core having an outer diameter of 24.3 mm, an inner diameter of 13.8 mm, and a height of 9.7 mm.

Thereafter, the core molded body was subjected to annealing for 1 hour at a temperature of 670 ° C. under a nitrogen atmosphere, and then coated on the surface of the core with an epoxy resin having a thickness of 100 μm.

Inductance, DC overlap characteristics, total resistance and magnetic core loss of the prepared soft magnetic cores were measured, and the results are shown in Table 1.

To evaluate the magnetic properties, winding 50 times (48 times in the case of amorphous core) in two layers with an enamelled copper wire of 0.25 mm diameter on the core coated with epoxy resin and measuring the inductance (L: μH) using a precision LCR meter. , Permeability (μ) is obtained by the relational formula of the toroidal core represented by Equation 1 below, and the Q value (Quality Factor) is measured. The measurement conditions were 100 Hz, AC voltage 1 V, and DC not superimposed (I _DC = 0 A).

Where L is the inductance (μH), μ is the permeability of the core, N is the number of turns, A is the longitudinal area of the core (cm 2), and l is the length of the average path (cm).

In addition, DC superimposition characteristics are examined by measuring the change of permeability by changing DC current, in which the measurement conditions are frequency 1㎑, AC voltage 1V, and measurement magnetization strength (H _DC ) is 190 Oe (DC current I = 40A). to be.

The total resistance of the core prepared as described above is calculated by the following equation (2).

Where RT is the total resistance (Ω), RDC is the DC resistance, RAC is the AC resistance, f is the measurement frequency, and L is the inductance (μH). At this time, the measurement condition is a state of not overlapping the frequency 50kHz, AC voltage 1V, DC (I _DC = 0A).

Figure 2 is a graph showing the change in inductance according to the DC current of the soft magnetic core for power factor improving inductor and conventional amorphous core made of permalloy alloy powder according to the present invention.

As shown in FIG. 2, it can be seen that the DC overlapping characteristic value of the present invention material is significantly larger than the conventional material, and the total resistance is very low.

In addition, the conventional material is unstable in use because the inductance changes significantly at high current. Therefore, it can be said that the DC overlapping characteristics and the total resistance of the present invention are superior to those of the prior art.

As described above, the soft magnetic core for the power factor improving inductor manufactured by the permalloy alloy powder according to the present invention exhibits superior DC overlapping characteristics than the conventional soft magnetic core, has a lower total resistance, and has a lower magnetic core loss than the conventional amorphous core. This is less effective.

Claims (1)

A soft magnetic core for a power factor improving inductor made from a permalloy alloy powder, wherein the mol% of molybdenum (Mo), 4% to 38% to 48% of nickel (Ni) and the remaining amount of iron (Fe) are used as weight%.