JP2501859B2 - Switching regulator - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of a switching regulator used in various electronic devices and the like.

[Prior Art] Conventionally, various magnetic parts have been used for switching regulators. FIG. 1 shows a circuit configuration example of a conventional switching regulator. This circuit configuration example is a magnetic control type switching regulator, and magnetic parts include normal mode choke, common mode choke,
Main transformers, drive transformers, current transformers, saturable reactors, noise absorbers and smooth chokes are used.

Ferrite is the mainstream of the magnetic material used for these magnetic parts, and a Co-based amorphous core is used for some parts, such as a saturable reactor, and an iron dust core is used for a normal mode choke. Further, as for the smooth choke, an Fe-based amorphous core, a Mo permalloy dust core, and an Fe-Al-Si alloy dust core are also used in applications where miniaturization is required. In the case of common mode chokes, ferrite is the mainstream, but partly amorphous.

Such an example is described in the materials such as the 37th meeting of Japan Society for Applied Magnetics.

[Problems to be Solved by the Invention] However, the switching regulator using the magnetic component has various problems.

When ferrite is used for the main transformer, the saturation magnetic flux density is low and the core loss is not sufficiently low.
There is a problem that not only the magnetic core becomes large and the switching regulator as a whole becomes large, but also the efficiency is lowered. or,
When a low-loss Co-based amorphous core is used, the switching regulator may not operate well due to a large change over time.

In addition, Co-based amorphous cores are mainly used for saturable reactors and noise absorbers, but because the saturation magnetic flux density is low, the magnetic core cannot be downsized when designing a large control magnetic flux, etc. There is a problem that it becomes large.

For the smooth choke, ferrite is mainly used in terms of price, but an Fe-based amorphous core or the like is used in terms of downsizing. However, the Fe-based amorphous core has a large magnetostriction and may cause a beat when excited, which is a problem. Further, in order to form the gap with high accuracy, impregnation causes a significant increase in core loss due to the effect of magnetostriction and intense heat generation, and when the temperature changes, the internal stress of the Fe-based amorphous alloy changes due to the cured resin, There is a drawback that the direct current superposition characteristic changes. For this reason, when designing the switching regulator, it was necessary to design with a considerable margin.

Ferrite is mainly used for the common mode choke, but the magnetic permeability is at most about 10,000 on the low frequency side, and especially the magnetic permeability of several hundred kHz or less is insufficient and noise on the low frequency side cannot be sufficiently removed. There was a problem that the surrounding electronic devices malfunctioned.

[Means for Solving Problems] As a result of intensive studies in order to solve the above problems, the present inventors have found that the general formula: Fe _{100-x-y-z-α-β-γ} Cu _x Si _y B _z M '
_α M ″ _β X _γ (atomic%) (where M ′ is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo, and M ″ is V, Cr, Mn , A white metal element, at least one element selected from the group consisting of Sc, Y, Au, Zn, Re, X is selected from the group consisting of C, P, Ge, Ga, Sb, In, Be, As At least one element, x, y, z, α,
β and γ are 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 30, 0 ≦ z ≦ 2, respectively
5,5 ≦ y + z ≦ 30, 0.1 ≦ α ≦ 30, 0 ≦ β ≦ 10 and 0 ≦ γ ≦ 1
Satisfies 0. ) Has a composition represented by at least 50% of the structure is composed of fine crystal grains, and the average grain size measured by the maximum dimension of each crystal grain is 1000 Å or less.
It was found that a switching regulator having excellent characteristics can be obtained when it is used for all or part of the invention, and the present invention was conceived.

In the alloy according to the present invention, Cu is an essential element, and the content X thereof is in the range of 0.1 to 3 atom%.

Further, M ′ is an essential element in the alloy according to the present invention, and has the effect of refining the crystal grains by complex addition with Cu, and is composed of Nb, W, Ta, Zr, Hf, Ti and Mo. It is at least one element selected from the group consisting of:

The alloy according to the present invention is usually obtained by a step of obtaining an amorphous alloy having the above composition by a liquid quenching method such as a single roll method or a twin roll method, and a heat treatment step of heating the amorphous alloy to form ultrafine crystal grains. You can

The crystal grains formed by heat treatment are mainly composed of bcc Fe solid solution, and are composed of ultra-fine and almost uniformly distributed crystal grains with a grain size of 1000Å or less, but excellent soft magnetism is often a grain size of 500Å or less . Especially in the case of alloys showing excellent soft magnetism, the average particle size is often 20 to 200Å. The part of the alloy composition other than the microcrystals is mainly amorphous. It should be noted that the alloy according to the present invention exhibits sufficiently excellent characteristics even when the proportion of fine crystal grains is substantially 100%, and a switching regulator using a magnetic component made of this alloy can be made compact and highly efficient. .

Si and B are elements useful for refining alloys, adjusting magnetostriction, improving soft magnetic properties, and the like. The alloy according to the present invention is preferably obtained by once forming an amorphous alloy by adding and hardening Si and B and then forming fine crystal grains by heat treatment.

The preferable Si content y and B content z are 0 ≦ y ≦ 30,0.
≦ z ≦ 25, 5 ≦ y + z ≦ 30. M ″ is at least one element selected from the group consisting of V, Cr, Mn, white metal elements, Sc, Y, Au, Zn, and Re, and has the effect of improving corrosion resistance and adjusting magnetic properties. And the content β is 0 ≦ β ≦ 10
Is.

X is at least one element selected from the group consisting of C, P, Ge, Ga, Sb, In, Be and As, and the content γ is 0 ≦ γ
≦ 10.

These elements have the effects of adjusting magnetostriction and magnetic properties and refining crystal grains.

The magnetic component according to the present invention is formed of the above-mentioned alloy and is applicable to all magnetic components used in a switching regulator.
When a switching regulator is constructed by applying it to a main transformer, smoothing choke, common mode choke, etc., a particularly excellent one is obtained.

[Examples] Hereinafter, the present invention will be described according to Examples, but the present invention is not limited thereto.

Embodiment 1 FIG. 2 shows an example of a circuit of a magnetic control type switching regulator.

In the figure, 1 is a switching element, 2 is a main transformer,
3; 4 are the primary winding and the secondary winding of the main transformer 2. 5
Is a saturable reactor, 6 is a rectifier circuit, 7 is a constant voltage control circuit, and 8a and 8b are DC output terminals.

 Next, the operation of this circuit will be described.

A pulsed voltage is induced in the secondary winding 4 of the main transformer 2 by turning ON / OFF the switching element 1 connected to the primary winding 3 to which the DC voltage is applied. This voltage passes through the saturable reactor 5 and the rectifier circuit, and the output terminals 8a and 8b.
Appears as a DC voltage. At this time, the positive pulse current i ₁
The saturable reactor 5 due to reaches the saturation point A in Fig. 4a, and returns to the Br point when i ₁ becomes zero. The negative pulse current i ₂ is a control current, and if this value becomes large, the operating point to be reset gradually shifts from point B to point C. When i ₂ becomes large and the operation from point C to point A is repeated, the impedance of the saturable reactor becomes maximum and the voltage drop also becomes maximum. The magnetic amplifier method is a method in which the voltage drop due to the saturable reactor is changed by the control current i ₂ and the output voltage is kept constant.

An important design issue for this approach is the choice of saturable reactor material. As for material performance, (1) large squareness ratio of BH curve, (2) small coercive force Hc,
(3) It is required that the plate be as thin as possible. So far, 50% Ni has been mainly used to satisfy the above performance.
Permalloy of the system was the mainstream.

As shown in FIG. 3, it has a toroidal shape in which a thin plate of about 25 μ is spirally wound.

This type of magnetic core has a high saturation magnetic flux density and a high squareness ratio and is suitable for a saturable reactor.However, in the case of a switching regulator driven at a high frequency, especially at a frequency of several tens of kHz or more, the core loss is large and the temperature rises sharply, resulting in a decrease in efficiency. Can not. Therefore, in recent years, a saturable reactor made of low-loss Co-based amorphous material is used, but it is expensive and the saturation magnetic flux density Bs is low, so in the frequency band of several hundred kHz or less, the magnetic core becomes large due to Bs restriction. Switching may cause the regulator to become large.

Therefore, a saturable reactor made of the above alloy represented by the composition of Fe _73.5 Cu ₁ Nb ₃ Si _13.5 B ₉ (atomic%) was prepared in the magnetic control type switching regulator of the circuit as shown in FIG. Used as the saturable reactor shown. In this case, all other magnetic parts were made of ferrite.

The results of measurement of core temperature rise, output voltage, and switching regulator efficiency are shown in Fig. 4. The driving frequency of the switching regulator is 100kHz and the output is 12V 4V (mag amp control).

For comparison, the results of a conventional switching regulator using a permalloy core as a saturable reactor are also shown.

The switching regulator of the present invention is superior to the conventional switching regulator in that the temperature rise of the core is small, the efficiency η of the switching regulator is high, and the output voltage hardly changes.

Example 2 A smooth choke coil with a gap made of the alloy ribbon represented by the composition of Fe _78.8 Cu _1.2 Si ₈ B ₉ Nb ₃ (atomic%) was prepared and used as the smooth choke coil of FIG.
Create a switching regulator that drives at 100kHz,
The temperature rise and the efficiency of the switching regulator were measured.

For comparison, we fabricated a switching regulator using a smooth choke coil made of Fe ₇₈ Si ₉ B ₁₃ amorphous alloy (atomic%).

The efficiency was 2% higher in the circuit of the present invention, and the temperature rise of the choke coil was lower by 6 ° C.

Example 3 A saturable reactor is shown in FIGS. 6 (a), (b), (c) and (d).
An example of the circuit of the switching regulator of the present invention, which is driven at 300 kHz, in which the above alloy is applied to SR is shown.

The efficiency of each switching regulator is improved by about 0.5 to 3% over the conventional switching regulator using the permalloy magnetic core, and the superiority of the switching regulator of the present invention was confirmed.

Example 4 A winding core made of the alloy ribbon having a composition of Fe _75.5 Cu ₁ Nb _2.5 Si _13.5 B ₇ Ga _0.5 (atomic%) is used for the main transformer TR of the 500 kHz resonant switching regulator shown in FIG. The temperature rise of the switching regulator and the main transformer and the efficiency of the switching regulator were measured.

The efficiency was 83% and the temperature rise was 31 ° C, which was 2% more efficient and 7 ° C higher in temperature than a switching regulator using a main transformer made of Fe-based amorphous alloy.

Example 5 Fe _{72.5 is used as} a common mode choke on the AC input side of a 100 kHz drive switching regulator having the circuit configuration shown in FIG.
A switching regulator was constructed using a common mode choke made of an alloy with a composition of Cu ₁ Nb ₃ Cr _0.5 Si _13.5 B ₉ Ge _0.5 (atomic%). Next, this AC input leakage noise terminal voltage was measured.

 The obtained results are shown in FIG.

The present invention switching regulator is the drive frequency
The high-frequency noise level higher than 100 kHz is lower than that of the conventional switching regulator, and the adverse effect on the surrounding electronic devices is reduced, which is preferable.

[Effects of the Invention] According to the present invention, a highly efficient switching regulator with a small temperature rise in magnetic parts and a highly reliable switching regulator can be obtained, and the effect is remarkable.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a circuit configuration of a switching regulator, FIG. 2 is a diagram showing an example of a circuit of a magnetic control type switching regulator, and FIG. 3 is an example of a shape of a winding magnetic core used in a saturable reactor. 4 and FIG. 4 are diagrams showing the output voltage, efficiency η, and core case surface temperature ΔT of the switching regulator of the present invention and the conventional switching regulator as a function of load current, FIG. 5, FIG. 6, FIG. Is a diagram showing a circuit example of the switching regulator of the present invention, and FIG. 8 is a diagram showing an AC input leakage noise terminal voltage of the switching regulator of the present invention.

Claims (5)

(57) [Claims] 1. A general formula: Fe _{100-x-y-z-α-β-γ} Cu _x Si _y B _z M '.
_α M ″ _β X _γ (atomic%) (where M ′ is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo, and M ″ is V, Cr, Mn , At least one element selected from the group consisting of white metal elements, Sc, Y, Au, Zn, Re, X is selected from the group consisting of C, P, Ge, Ga, Sb, In, Be, As At least one element, x, y, z, α,
β and γ are 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 30, 0 ≦ z ≦ 2, respectively
5,5 ≦ y + z ≦ 30, 0.1 ≦ α ≦ 30, 0 ≦ β ≦ 10 and 0 ≦ γ ≦ 1
Satisfies 0. ), At least 50% of the structure is composed of fine crystal grains, and the average grain size measured by the maximum dimension of each crystal grain is 1000 Å or less. A switching regulator characterized by being used for everything. 2. The switching regulator according to claim 1, wherein the magnetic component is a saturable reactor. 3. The switching regulator according to claim 1, wherein the magnetic component is a main transformer. 4. The switching regulator according to claim 1, wherein the magnetic component is a smooth choke. 5. The switching regulator according to claim 1, wherein the magnetic component is a common mode choke.