JP2633813B2 - Manufacturing method of reactor for switching circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a reactor for a switching circuit, which is inserted in series into a semiconductor element without arranging a control circuit for controlling a core for suppressing a current spike or the like. About.

[0002]

2. Description of the Related Art Conventionally, in a switching circuit for suppressing a large current in a high frequency region, for example, a switching power supply, a current spike or linking is likely to occur due to the characteristics of the semiconductor itself and other circuit factors. was there.

[0003] These phenomena prevent normalization of circuit operation,
Finally, there was a risk of destroying the semiconductor. Further, such a sudden change in current has been the largest cause of equipment noise.

Generally, when the polarity of a voltage applied to a semiconductor device such as a diode is rapidly reversed, the diode loses its function as a diode for a moment, and a current flows in the opposite direction. After a short time (recovery time), the diode recovers its function and no current flows in the reverse direction.
If the reverse current, that is, the current spike is large, the diode may be destroyed.

If a resonance element such as a coil and a capacitor is present in a circuit in which such a current spike has occurred, the current spike causes long and trailing ringing. Current spikes and ringing naturally cause the circuit to malfunction.

[0006] In addition to these acting as noise components included in the output, abrupt reversal of current causes electromagnetic noise. That is, noise is radiated to space in the form of radio waves.

[0007] These problems such as current spikes, ringing, and electromagnetic wave noise have become particularly problematic in a switching circuit such as a switching power supply for controlling a large current in a high frequency range.

[0008] In recent years, with the demand for strengthening international measures against such noise disturbances, measures for preventing noise generated in semiconductor devices have been strengthened, and prevention of noise has become an important problem.

[0009]

In order to suppress such current spikes and ringing, a switching circuit reactor is arranged in a semiconductor circuit.

However, since the core of the conventional switching circuit reactor is formed of ferrite, permalloy, or the like, it has not been possible to sufficiently suppress the core.

That is, when a ferrite core is used, the squareness ratio (Br / B ₁ ) and the saturation magnetic flux density are small, so that the suppression effect is small, and in order to be effective, the core shape needs to be large. is there. In addition, when a core made of permalloy is used, there is a problem that the coercive force (Hc) is large and it is not possible to cope with a higher frequency.

The present invention has been made in order to solve such a problem, and provides a method of manufacturing a reactor for a switching circuit, which can effectively prevent current spikes and ringing which cause noise. The purpose is to:

[0013]

A method for manufacturing a reactor for a switching circuit according to the present invention is represented by a general formula: Coa
MbM'cYd (wherein, M is one element selected from Fe and Mn, M 'is one or more elements selected from transition metals other than Fe and Mn, Y is
Represents one or more elements selected from Si, B, P and C, and a, b, c and d are atomic% satisfying the following formula. a + b + c + d = 100, 50 ≦ a ≦ 8
(0,0≤b≤10,0≤c≤10) is wound or laminated to form a toroidal core, and the core is heat-treated to obtain B ₁ ≧ 6 kG, 100 kHz. A core having characteristics of coercive force (Hc) ≦ 0.5 Oersted (Oe) and squareness ratio (Br / B ₁ ) ≧ 0.8 is manufactured, and the core and the conductor are combined to control the core. It is characterized in that it is inserted in series with a semiconductor element without disposing a control circuit.

The amorphous magnetic alloy which is the core material used in the present invention includes B ₁ ( ₁ Oe) at 100 kHz.
Is 6 kG or more, and the coercive force (H
c) is 0.5 Oe or less, and the squareness ratio (Br / B ₁ , B
r: residual magnetic flux density) of 0.8 or more, Co
aMbM'cYd (where M is Fe and Mn
M ′ is one or two or more elements selected from transition metals other than Fe and Mn;
Y represents one or more elements selected from Si, B, P and C, and a, b, c and d are atomic% satisfying the following formula. a + b + c + d = 100, 50 ≦ a ≦ 8
0,0 ≦ b ≦ 10,0 ≦ c ≦ 10).

Preferably, M 'is Cr, Ni, Nb, M
o, W, Zr, Ti, V, Ta, Hf, Re, Cu, Y
It is.

The reason for limiting the characteristics of the amorphous magnetic alloy as described above is that, for the first time, attention is paid to the magnetic flux density B ₁ at ₁ Oe in order to obtain the effects of the present invention.
The present inventors have found for the first time that by limiting the characteristics of the magnetic flux density B ₁ , coercive force (Hc) and squareness ratio (Br / B ₁ ) at z, they have sufficient characteristics at other frequencies. It depends.

In the present invention, a toroidal core is formed by winding an amorphous magnetic alloy in a ribbon shape by a single roll method, or by laminating punched pieces on a ribbon to form a toroidal core. After the core is heat-treated, the winding is applied a plurality of times to obtain a switching circuit reactor. The characteristics specified in the present invention can be obtained by changing the thickness of the amorphous magnetic alloy ribbon, heat treatment conditions, and the like.

By inserting the switching circuit reactor in series with the semiconductor element without disposing a control circuit for controlling the reactor, current spikes and ringing of the switching circuit can be suppressed.

[0019]

【Example】

Example 1 An amorphous magnetic alloy ribbon made of Co-Fe-Cr-Si-B was obtained by a single roll method. Magnesium oxide powder is applied to this to insulate it between layers, and 20 mm is placed in a 6 mm diameter quartz tube.
After winding, the quartz tube was pulled out to form a core. After the core was subjected to heat treatment, the core was covered with an epoxy resin and insulated, and the insulated conductor was wound four times to obtain the reactor of the present invention.

As shown in FIG. 1, the reactor 2 thus obtained is connected to a diode 1 in a switching power supply circuit.
At 100kHz (output from switching power supply / input to transformer in circuit,%),
The magnitude of the current spike (A), the degree of ringing, and the high-frequency noise (the noise of a circuit without a reactor is
db).

Further, two insulated conductors are wound around the core, and an AC hysteresis curve at 100 kHz is obtained using an AC magnetic field measuring device under an external magnetic field of ₁ Oe. From this curve, the magnetic flux density B _{1 at 1} Oe is maintained. Magnetic force (H
c) and the squareness ratio (Br / B ₁ ) were determined.

For comparison with the present invention, a similar test was conducted on a reactor having a core made of ferrite or permalloy. In addition, the magnitude of the current spike, the degree of ringing, and the high-frequency noise were measured for a circuit without a reactor.

The results are shown in Table 1.

[0024]

[Table 1] As is clear from Table 1, the switching circuit reactor according to the present invention was able to reduce current spikes, generate no ringing, and extremely reduce high-frequency noise, as compared with the related art.

Example 2 An amorphous magnetic alloy ribbon having each composition shown in Table 2 was obtained by a single roll method. Magnesium oxide powder is applied to this to insulate it between layers.
After being wound around a toroidal core having a size of mm × inner diameter 6 mm × height 4 mm, heat treatment was performed to obtain a core.

Further, two insulated wires are wound around the core, and an AC hysteresis curve at 100 kHz is obtained using an AC magnetic field measuring device under an external magnetic field of ₁ Oe. From this curve, the magnetic flux density B _{1 at 1} Oe is maintained. Magnetic force (H
c) and the squareness ratio (Br / B ₁ ) were determined.

The results are shown in Table 2.

[0028]

[Table 2] As is clear from Table 2 above, B
_It can be seen that ₁ ≧ 6 kG, Br / B ₁ ≧ 80%, and Hc ≦ 0.5 Oe.

All of these samples were inserted in series with a flywheel diode as a switching power supply in the same manner as in Example 1, and the efficiency (output / input) at 100 kHz was determined. The results were all 78 to 80%.

In this switching circuit,
No current spikes or ringing were observed, and the circuit operation could be normalized.

[0031]

According to the method for manufacturing a reactor for a switching circuit of the present invention, it is possible to effectively prevent current spikes and ringing which cause noise, to normalize circuit operation, and to protect a semiconductor. Thus, it is possible to manufacture a switching circuit reactor that enables the above.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit used for a performance test of a reactor of the present invention.

[Explanation of symbols]

 1. Diode 2. Reactor

Claims (1)

(57) [Claims] 1. A general formula: CoaMbM′cYd (wherein, M is one element selected from Fe and Mn, and M ′ is one or two elements selected from transition metals other than Fe and Mn) Y represents one or more elements selected from Si, B, P and C;
b, c, and d are atomic% satisfying the following equation. a + b +
c + d = 100, 50 ≦ a ≦ 80, 0 ≦ b ≦ 10, 0 ≦
c ≦ 10) to form a toroidal core by winding or laminating an amorphous magnetic alloy ribbon, and by heat-treating the core, at 100 kHz, B ₁ ≧ 6 kG, coercive force (Hc) ≦ 0.5 Oersted. , Squareness ratio (Br / B ₁ )
A switching circuit comprising: manufacturing a core having characteristics of ≧ 0.8, combining the core and a conductor, and inserting the core in series with a semiconductor element without disposing a control circuit for controlling the core. Manufacturing method for reactors.