JPH0133926B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a coil core for a power line filter. More specifically, when a magnetic core made of an amorphous magnetic alloy is used to form a coil and applied to a chiyoke coil for a power line filter or an LC noise filter, high voltage pulse noise that cannot be removed by conventional filters is produced. This invention relates to a coil magnetic core that can block input extremely effectively. When inputting power to a device from a power line or power circuit, noise current superimposed on the power supply current or other unnecessary current may enter the device or leak from the device to the outside.
For this reason, a power line filter is inserted into the power line or power circuit to prevent these problems. For such power line filters, it is often advantageous to use a coil as a filter functional element due to its robustness, etc., and it is often advantageous to use a coil as a filter function element. Common mode or differential mode LC noise filters are often used to remove superimposed noise. Conventionally, ferrite, powder material, etc. have been used as the material for forming the magnetic core of a power line filter coil such as a chiyoke coil or a common mode or differential mode chiyoke coil for an LC noise filter. .
However, the ferrite magnetic core has a saturation magnetic flux density (Bs)
For example, if the coil is used as a common mode choke coil to form a common mode noise filter and inserted into a 100V AC power line, the magnetic core will become saturated when large voltage noise is input, making it difficult to use it effectively. This can lead to equipment malfunctions. Further, although the powder magnetic core has a high saturation magnetic velocity density, it has a low magnetic permeability and a low inductance with respect to input voltage, so that it cannot effectively block large voltage noise input. Under these circumstances, the applicant of this application
Previously, we proposed using a closed magnetic circuit core made of an amorphous magnetic alloy as the core of a power line filter coil. The magnetic core according to the above proposal has a significantly improved ability to stop high-voltage noise current pulses. However, the noise current pulse superimposed on this power line or power supply circuit is often 1000V.
As described above, this is generated as an extremely large pulse-like voltage of 1 μsec or less. It has been found that closed magnetic circuit cores made of ordinary amorphous magnetic alloys cannot withstand such large voltage pulse-like noises in practical use. The present invention has been made in view of the above-mentioned circumstances, and when a closed magnetic circuit core made of a substantially amorphous magnetic alloy is used as a coil core for a power line filter, a predetermined treatment is performed at the time of making the core. By doing so, we aim to improve the magnetic core characteristics so that they can effectively block even extremely large voltage pulse-like noise, and to find critical conditions for the magnetic core characteristics that exhibit large stopping power. be its main purpose. The inventors of the present invention have conducted extensive studies regarding these objectives, and have found that the magnetic properties of a magnetic core made of an amorphous magnetic alloy at 50KHz are an extremely good indicator for eliminating large voltage pulse-like noise of 1000V or more. And, when measuring the magnetic flux density B ₂ and the saturation magnetic flux density Bs at H = 2 Oe on the average magnetization curve at 50KHz, B ₂ is 2000G or more,
Moreover, it was discovered that an extremely large blocking ability is exhibited only when B ₂ is 0.7 times or less than Bs, and this new knowledge led to the present invention. That is, the present invention provides a coil magnetic core for a power line filter made of an amorphous magnetic alloy.
The purpose is to satisfy the following formula when measuring the B-H loop at 50KHz. Formula 2000G≦B ₂ ≦0.7Bs Here, Bs is the saturation magnetic flux density in the B-H loop, and B ₂ is the value of B at H = 2Oe on the average magnetic subtraction curve found from the B-H loop at 50KHz. be. In this case, the average magnetization curve is, as is well known, B
- This is a curve obtained by connecting the midpoints of two points showing the same B value on the H loop. The coil magnetic core for a power line filter of the present invention is
The B-H characteristic at 50KHz satisfies the relationship expressed by the above formula. If this relationship is not satisfied, it is not possible to construct a power line filter coil that can effectively remove pulsed noise as high as 1000V. In this case, in the above formula I, more preferable results are obtained when B ₂ ≧3000G, especially B ₂ ≧4000G. In addition, while maintaining the relationship shown in the above formula, Bs≧400G, especially Bs
More favorable results will be obtained if ≧7000G. In order to determine whether such a relationship exists, follow the usual method: apply two windings with a predetermined number of turns to the magnetic core, and apply a 50K voltage to one of the windings through a predetermined resistance.
This may be done by inputting a Hz signal, measuring the output of the other winding, and measuring its B-H loop. In the present invention, the predetermined effects of the present invention are achieved by using the relationship shown by the above formula as a critical condition, and as long as such a relationship is satisfied, the composition of the substantially amorphous magnetic alloy is may be of various types. . This is because the characteristics of a magnetic core made of an amorphous magnetic alloy vary depending on its composition, the treatment history during the formation of the magnetic core, the structure of the magnetic core, etc. However, in general, it is preferable that the substantially amorphous magnetic alloy forming the coil magnetic core for a power line filter of the present invention has a composition represented by the following formula. This is because at that time, it becomes easy to give the magnetic core the B-H characteristic shown by the above formula. Formula (Fe _p Co _q Ni _r ) _x X _y Y _zwhere , X is one or more glass elements, and Y
is one or more transition elements other than the iron group. Also,
x+y+z=100at%, y is 10-35at%,
More preferably 15-30at%, z is 0-5at%
%. Furthermore, p+q+r=100%, and p is
60-100%, and r is 0-40%. In this case, the one or more vitrifying elements constituting X include Si, B, P, C, Ge, Sn, Ga,
One or more of In, Sb, Al, Zr, etc. can be used, and when X is expressed as Si _k B _l X ⁽¹⁾ m, more preferable results are obtained. In this Si _k B _l X ⁽¹⁾ m, k+l+m=100%, and k/k+l
is from 0 to 0.7, and m is from 0 to 0.4. AlsoX ⁽¹⁾
is one or more of P, C, Ge, and Sn, more preferably P and/or C;
When X ⁽¹⁾ is expressed as P _s C _t , S/k+l+m is 0
~0.1, t/k+l+m is 0-0.3. On the other hand, one or more non-iron group transition elements constituting Y include Co, Fe, and Ni among the first to third transition series in a broad sense, that is, Sc to Zn, Y to Cd, and La to Hg. It may be any one or more types other than the above. Such magnetic alloys are substantially amorphous, typically 10-100 .mu.m thick thin sheets, from which they are generally formed as generally annular magnetic cores. In this case, being annular means that it is a cylindrical body whose cross section is annular, such as a circular ring, a circular ring, a quadrangular ring, etc., as is known in the art. Furthermore, in order to form an annular magnetic core using an amorphous magnetic alloy thin plate, as shown in FIG. The magnetic core 2 may be formed by laminating the magnetic core 2 through the magnetic core 2. However, in terms of easier manufacture of the magnetic core, it is preferable that the annular magnetic core 2 is formed from a thin plate 15 as a wound core as shown in FIGS. 2 and 3. In this case, in both figures, the magnetic core 2 is a thin plate 15 of an amorphous magnetic alloy.
is wound around a winding core or a winding frame (not shown) with an insulating layer interposed therebetween as necessary, so as to have an annular cross section, in this case an annular shape. In this way, the above-mentioned magnetic core whose B-H characteristic at 50 KHz has the relationship shown by the above formula is generally created as follows. First, a thin plate of an amorphous magnetic alloy is created. In order to produce a thin plate of an amorphous magnetic alloy, an alloy having a corresponding composition may be ultra-quenched from the liquid phase according to a known high-speed quenching method. In order to obtain an amorphous magnetic alloy thin plate by ultra-quenching from the liquid phase, an alloy of the corresponding composition is melted to form a melt, and this melt is heated from the molten state to approximately 10 ⁴ °C/sec or more, usually 10 ⁴ This may be achieved by ultra-rapid cooling at a cooling rate of ~10 ⁶ °C/sec and cooling solidification. In order to ultra-quench the molten alloy liquid, various methods such as the known twin-roll method, single-roll method, or inside-in-division method may be used. Therefore, the melting conditions for the alloy, the jetting conditions for the alloy liquid, the shape and dimensions of the nozzle during jetting, the shape, dimensions, material, etc. of the cooling body such as twin rolls are within the range of conditions for the known ultra-quenching method. It may be determined as appropriate. Furthermore, when melting the alloy, it is preferable to carry out the process in an inert gas such as argon, or while an inert gas is flowing in. However, the spouting of this melt can be carried out in either an inert gas or air atmosphere. You may go against them. In this way, substantially amorphous and 10
A long continuous thin plate having a thickness of about 100 μm and a width depending on the purpose of use is produced. A magnetic core is then formed from such a thin plate.
In order to form a magnetic core from a thin plate, as described above, a thin plate may be cut into a predetermined shape, for example, an annular shape, and a plurality of thin plates may be used to form a laminate, preferably with a known insulating layer interposed therebetween. In a preferred embodiment, the thin plate is wound to form a wound magnetic core with a known insulating layer interposed therebetween if necessary. In this case, in order to wind a long continuous thin plate to form a wound magnetic core, the thin plate may be wound around a specified winding core and then fixed, or the thin plate may be wound on a winding core and then the winding core removed and fixed. There are various methods, such as fixing the wound thin plate within the winding frame. In this case, it is necessary to perform some kind of heat treatment on the thin plate before forming the magnetic core from the thin plate and/or after forming the wound core. When a thin plate immediately after being manufactured by the high-speed quenching method is used as it is and a magnetic core is formed from it, the B-
This is because the H characteristic does not satisfy the relationship shown in the above formula, and the desired effect of the present invention is not achieved. In the present invention, there are various heat treatments for making the magnetic core satisfy the relationship shown in the above formula at 50 KHz. One such embodiment is heat treatment of the thin plate before forming the magnetic core. This thin plate heat treatment is performed on a long continuous thin plate before the magnetic core is formed, or on a thin plate punched or etched into a predetermined shape. It is applied at a temperature above point Tc. In this case, depending on the composition of the amorphous magnetic alloy, even if the amorphous magnetic alloy is within the preferred composition range shown by the above formula, the Curie point Tc
may be Tc≧Tx, in which case this heat treatment cannot be applied; however, for materials where Tc<Tx, heat treatment is performed in a non-magnetic field at a temperature above Tc and below Tx, and then If a magnetic core is formed, it may be possible to make the magnetic core have the relationship shown in the above formula. On the other hand, the heat treatment applied to the thin plate before forming the magnetic core, which belongs to the same embodiment as above, includes heat treatment in a magnetic field performed at a temperature lower than Tc and Tx. If such heat treatment in a magnetic field is performed, the B ₂ can be increased to a larger value than when heat treatment is performed in the absence of a magnetic field.
For example, it can be set to 3000 to 4000G or more, and the noise blocking ability is further improved. In this case, the applied magnetic field usually has a stationary magnetic field axis and is applied to the thin plate from a predetermined direction. Therefore, the magnetic field axis of the applied magnetic field may be parallel to the direction of the magnetic path when the thin plates are formed into a wound core or a laminated core. However, when applying a magnetic field parallel to the magnetic path direction in this way, B ₂ increases to over 4000G, but at the same time B ₂ approaches 0.7Bs, and B ₂ > 0.7Bs. be. When B ₂ exceeds 0.7Bs, the noise rejection ability deteriorates. Under these circumstances, it is generally preferable that the magnetic field axis of the applied magnetic field is not parallel to the magnetic path direction when a thin plate is used as the magnetic core. FIG. 4 shows a preferred example of such a case.
In the figure, a predetermined angle θ (preferably
A linear magnetic field H is generated with an intersecting angle of 45 to 90 degrees, while the thin plate 15 is continuously moved in the same direction as its longitudinal direction l (in the direction of arrow a in the figure) and passes through this magnetic field region. It is designed to do so. In this case, it is preferable that the magnetic field axis of the magnetic field H be approximately parallel to the thin plate surface, and the magnetic field H may vary either in direct current or alternating current, and the magnetic field strength is approximately 10 Oe or more. It is better to In this way, Tc and
By performing heat treatment by selecting a predetermined intersection angle θ at a temperature below Tx and cooling preferably in a magnetic field, the magnetic core can then be formed as described above to have the relationship shown in the above equation. . The heat treatment belonging to the first aspect, which is performed on a thin plate before forming a magnetic core, is as described above, but especially when forming a wound magnetic core from a thin plate, excessive strain is often applied to the thin plate. Therefore, as a second aspect, it is generally advantageous to form a magnetic core by winding or laminating thin plates as described above, and then subjecting the magnetic core to a predetermined heat treatment. Of course, also in this second aspect, the processing of the first aspect can be performed in advance and both can be used together. An example of this second aspect is heat treatment performed on the magnetic core in a non-magnetic field at a temperature greater than or equal to Tc and less than Tx. When a thin plate having a composition that can be subjected to such heat treatment is used, the relationship shown in the above equation can be effectively caused in the magnetic core by selecting the treatment conditions. On the other hand, also in this second aspect, heat treatment in a static magnetic field as described above is a more effective means for realizing the relationship shown in the above formula. This is because heat treatment in a magnetic field increases B ₂ to a large value of 3,000 to 4,000 G or more, and the noise blocking ability becomes extremely large. In this case, when the magnetic core is wound and energized during the heat treatment, a magnetic field is applied in the direction of the magnetic path of the magnetic core. However, in such a case, as in the case described above, B ₂ becomes an extremely large value, but
It is close to 0.7Bs, and may exceed 0.7Bs.
On the contrary, the noise blocking ability decreases. For this reason, in general, an external magnetic field with a nearly linear magnetic field axis is
It is preferable to apply it substantially uniformly over the entire magnetic core. That is, as shown in FIG. 5, the applied magnetic field is a magnetic field H ₁ parallel to the radial direction of the magnetic core 2.
The magnetic core 2 can be placed inside the magnetic core 2, or the magnetic core 2 can be placed in an external magnetic field _H2 parallel to the width direction of the magnetic core 2.
Furthermore, it is preferable to arrange the magnetic core 2 in a linear parallel external magnetic field synthesized from the combination of the magnetic fields H ₁ and H ₂ . By appropriately selecting the direction in which this magnetic field is applied to the magnetic core, the relationship shown in the above formula can be realized, and B ₂ can be adjusted to 3000 to 4000G.
It is possible to obtain an extremely preferable value of 0.7 Bs or less. As above, the applied magnetic field in this case, regardless of whether it is direct current or alternating current, is preferably about 10 Oe or more in strength, and the heating temperature is approximately below Tx and Tc.
The temperature is preferably 200°C or higher. Further, cooling after heating is preferably performed in a magnetic field. Note that the various heat treatments described above may be performed in any atmosphere of air, vacuum, or inert gas. In this way, the magnetic core of the present invention having the relationship shown in the above equation is created, and such a magnetic core is wound with a winding wire and configured as a power line filter coil. In this case, the first
As shown in the figure and FIG. 2, the winding 3 can be wound to form a chiyoke coil 4. At this time, the chiyoke coil formed from the magnetic core of the present invention can be used for a power supply line and can effectively remove pulse-like noise at a voltage as high as 1000V. However, in order to further increase the effect of the present invention, two windings 3 as shown in FIG.
1 and 32 to constitute the common mode York coil 40. In this case, the winding directions of the windings 31 and 32 are determined so that the magnetic fluxes due to the reciprocating currents cancel each other out. For example, a circuit as shown in FIG. A noise filter is formed. In this case, in FIG. 6, a capacitor C ₁ is placed at one end between the pair of windings 31 and 32 of the common mode choke coil, and a capacitor C ₂ , is placed at the other end.
C ₃ , C ₄ and resistors R ₁ , R ₂ are connected, and the connection point of capacitors C ₃ , C ₄ and resistors R ₁ , R ₂ is grounded. When such a common mode noise filter is inserted into a power supply line, even if pulsed noise with a voltage as high as 1000V is input, the noise output voltage shows an extremely small value, and it exhibits an extremely effective noise filter function. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Has a composition of Fe ₈₀ B ₁₈ Si ₂ , thickness 30 μm, width 8 mm
A continuous thin plate of an almost completely amorphous magnetic alloy was prepared by a high-speed quenching method. The crystallization temperature Tx of this alloy thin plate was 500°C, and the Curie point Tc was 400°C. Next, this thin plate was cut to a predetermined length, and the outer diameter was 31 mm.
The core was wound into a toroidal shape with a diameter of 19 mm, an inner diameter of 19 mm, and a width of 8 mm, and was designated as magnetic core A. To such a wound magnetic core A, a linear parallel external magnetic field of 1000 Oe was applied in the direction of the magnetic core (direction H ₁ in FIG. 5). After heating at 440°C for 15 minutes in a magnetic field, it was cooled in a furnace, also in a magnetic field. Through such treatment, magnetic core B was obtained. Furthermore, a linear parallel magnetic field of 1000 Oe was applied to the wound magnetic core A formed as described above, not in the radial direction but in the width direction (the direction of H ₂ in FIG. 5), and the magnetic core A was heated at 440° C. A magnetic core C was obtained by heating for 15 minutes and cooling in a furnace. Furthermore, a wound magnetic core A formed as described above
The magnetic core D was then heated at 440° C. for 15 minutes and allowed to cool without applying a magnetic field. On the other hand, winding is applied to the wound magnetic core A formed as described above, and the thin plate winding direction (the circumferential direction of the magnetic core) is
A magnetic field of 10 Oe was induced in the core, and in this magnetic field, heating was performed at 440° C. for 15 minutes and furnace cooling was performed in the same manner as described above, to obtain a magnetic core E. For each of the magnetic cores A to E thus obtained, two windings were applied with a predetermined number of turns, a 50KHz signal was input to one winding through a predetermined resistance, and the output of the other winding was measured. Then, the B-H loop was measured, an average magnetization curve was determined, and the value of B (B ₂ ) at H=2Oe on this curve was determined. In addition, the saturation magnetic flux density Bs at 50KHz was measured using a vibrating magnetometer.
The results are shown in Table 1 below. On the other hand, for the magnetic cores A to E obtained in this way,
As shown in FIG. 3, two windings 31 and 32 having a predetermined number of turns were wound so that the magnetic fluxes due to the reciprocating currents were canceled out to create a common mode York coil 40. Then, a common mode noise filter as shown in FIG. 6 was fabricated using the common mode choke coil 40 thus fabricated and capacitors C ₁ , C ₂ , C ₃ , and C ₄ . In this case, a 0.22 μF capacitor C ₁ is connected between one end of the windings 31 and 32, and a 0.22 μF capacitor C ₂ is connected to the other end.
C ₃ and C ₄ of 5000pF are connected. Using such a common mode noise filter, one end of the capacitor _C1 is connected to the pulse generator PG through the 50Ω resistor _R3 , and the other end is connected to the pulse generator PG through the attenuator A, as shown in FIG.
Further, 50Ω resistors R ₁ and R 2 were connected in parallel with the capacitors C ₃ and C ₄ , respectively, the connection point of the resistors R ₁ and R ₂ was grounded, and one end of the resistor _{R 1 was} connected to an oscilloscope. Using such a measurement circuit, input a 1000V, 1μsec pulse from the pulse generator PG through the attenuator A to the common mode noise filter configured for each of the magnetic cores A to E, and measure the output voltage at that time. did. The results are also listed in Table 1.

[Table] From the results in Table 1, B-H when the magnetic core is 50KHz
It can be seen that a pulse-like large voltage noise input of as much as 1000V can be effectively removed only when the above-mentioned relationship regarding the characteristics is satisfied. In this case, it can be seen that when B ₂ becomes a value of 3000G or more, especially 4000G or more, the noise output voltage becomes extremely small. Also, B ₂ becomes even larger, 0.7Bs
On the contrary, as it approaches , the noise output voltage increases, and when it exceeds 0.7Bs, a considerably large noise output voltage occurs. Note that, as shown in FIG. 7, unlike the case shown in FIG. 6, when a measuring circuit in which both ends of the capacitor _C1 were connected was used, results exactly similar to those described above were obtained. Example 2 Three types of thickness 30 μm and width 8 mm shown in Table 2 below
obtained a continuous thin sheet of almost completely amorphous magnetic alloy of
As in Example 1, it was wound into a toroidal shape with an outer diameter of 31 mm and an inner diameter of 19 mm to obtain a wound magnetic core. Next, for each of the magnetic cores, one of the cores was subjected to heat treatment in a magnetic field at a temperature higher than Tc and lower than Tx as shown in Table 2 below, in accordance with Example 1. Regarding these six types of magnetic cores, as in Example 1,
When I measured the B-H loop at 50KHz,
The results shown in Table 2 were obtained for Bs and _B2 . In addition, as in the first embodiment, a common mode choke coil 40 as shown in FIG.
A 1000 V, 1 μsec pulse was input from the pulse generator PG through the attenuator A, and the output voltage at that time was measured, and the results shown in Table 2 were obtained. From the results in Table 2, for amorphous magnetic alloys of various compositions, only when the relationship of the above formula is satisfied,
It can be seen that a pulsed high voltage input of as much as 1000V can be effectively removed.

【table】 [Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a chiyoke coil for a power line filter constructed using the magnetic core of the present invention, and FIG. 2 is a plan view showing another example. FIG. 3 is a plan view showing an example of a common mode choke coil for a power line filter using the magnetic core of the present invention. 4 and 5 are diagrams for explaining one step in manufacturing the magnetic core of the present invention, respectively; FIG. 4 is a plan view of one example, and FIG. 5 is a perspective view of another example. It is a diagram. FIGS. 6 and 7 show a measurement circuit that constructs a common mode choke coil from the magnetic core of the present invention, forms a common mode noise filter using this, and measures the output voltage response to a pulse voltage input at that time. FIG. 11, 15...Amorphous magnetic alloy thin plate, 2...Magnetic core, 4...Chiyoke coil, 40...Common mode Chiyoke coil.

Claims (1)

[Claims] 1. When measuring the B-H loop at 50KHz of a power line filter coil core made of an amorphous magnetic alloy, 2000G≦B ₂ ≦
0.7Bs (Here, Bs represents the saturation magnetic flux density, and
_B2 represents the value of the magnetic flux density B at H=2Oe on the average magnetization curve determined from the B-H loop at 50KHz. ) A coil magnetic core for a power line filter, characterized by having the following relationship.