JPS58114401A - Superlow loss ferrite for power source - Google Patents

Abstract

PURPOSE:To contrive the reduction of power loss in a specific temperature region, by compositely adding a specific amount of CaO, Nb2O5 and SiO2 as the sub component to the ferrite powder of MnO, ZnO Fe2O3 as the main component. CONSTITUTION:To MnO, ZnO and Fe2O3 as the main component, CaO in 0.04- 0.2wt%, Nb2O5 in 0.1wt% or less (not including 0) and SiO2 in 0.05wt% or less (not including 0) are added as the sub component so that they are contained. When CaO becomes more than 0.2wt%, a ferrite sintered body with the lack of sintering is formed, and, when less than 0.04wt%, the natural resistance of the sintered body decreases too much resulting in the deterioration of the frequency characteristic. When Nb2O5 becomes more than 0.1wt%, an inhomogeneous crystal grain growth is caused resulting in the deterioration of te magnetic characteristic, and, when SiO2 becomes more than 0.05wt%, likewise, the magnetic characteristic deteriorates. Thereby, the power loss before and after 60- 80 deg.C can be extremely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to MrrZn-based ultra-low loss 7-elite for power supplies suitable for use in magnetic cores of DC-DC converter devices (high frequency power supplies).

Conventional Mn-Zn ferrites include CaO and S.
There were those to which Nb2O was added and those to which Nb2O was added alone. However, such conventional ferrite tends to cause large power loss when used in a DC-DC converter where the magnetic flux density is high and heat is generated.

In view of the above-mentioned points, the present invention aims to provide an ultra-low loss 7ELITE for power supply that can extremely reduce power loss at around 60 to 80°C.

The feature of the present invention is that 0.0% of CaO is added as a subcomponent to laerite powder mainly composed of MnO, ZnO, and Fe2O.
4 to 0.2% by weight, Nb, O, not including 0 and not more than 0.1% by weight, and 5in2 which does not contain 0 and not more than 0.05% by weight and is twisted and fired. .

Examples of the ultra-low loss ferrite for power supplies according to the present invention will be described below along with comparative examples.

r Comparative Example 1] Mn0 (35.5 mol%), Zn0 (
11.5 mol%), Fe20s (53.0%) as the main component, and 0.04% by weight of CaO and Si as secondary components.
8 under the conditions of a 25 kHz sine wave and 2000 fus when O2 was added to contain 0.018% by weight.
The power loss at 0° C. was 178 mW/co+3.

[Comparative Example 2'l'Mn0 (35.5 mol%), Zn
0 (11.5 mol%), Fe2O, (53.0%) as the main components,! The power loss at 80°C when CaO was added as the i11 component to contain 0.075% by weight and 0.018% by weight of 5in2 was 74III.
It was W/c-3. Note that this measurement condition is [Comparative Example 1]
] is the same as (Measured under the following conditions.) [Example 1] Mn0 (35.5 mol%), Zn0 (11,
5 mol%), Fe2e3 (53.0%) as the main component,
0.075% by weight of CaO, Nb2O,
0.03% by weight and 0.021% by weight of SiO.
The power loss at 80'C when added to contain was 43 mW/ca+'. In this case, the initial magnetic permeability μ at room temperature is 2300. Q is 110, jan(
δ/μ1)=3.95×10−′, and the Curie temperature was 22°. This temperature is high enough for power supply.

[Example 2] Mn0 (35.5 mol%), Zn0 (
11.5 mol%), Fe20a (53.0%) as the main component, CaO as the subcomponent 0.075% by weight, N
b2O5 0.05% by weight and C/S+02 Total 0
80″ when added to contain 0olBfi amount%
The power loss in C was 64IIIW/CIs:I.

[Example 3] Mn0 (35.5 mol%), Zn0 (
11,5, mol%), Fe2es (53,0%) as the main component, CaO as a subcomponent 0.075% by weight,
0.02% by weight of Nb2O5 and 0.018% of SiO2
The power loss at 80°C was 68 mW/Cm' when it was added to contain % by weight.

The relationship between additives and power loss in the comparative examples and examples of the present invention is summarized in Table 1 below.

Table 1 (wt%) (Theory W/c Theory 3) From this table 1, in the case of Examples 1 and 2.3 of the present invention, Comparative Examples 1 and 2
It can be seen that the power loss at 80°C is significantly reduced.

Next, the relationship between the amount of each additive added and power loss is shown in FIGS. 1 and 2.

In Figure 1, 5in2 is 0.021% by weight and N b 20
The effect of addition of C a O on power loss at 80° C. is shown when the amount of addition of s is used as a parameter. In the figure, curve (a) is 0.0 when N b 20 s is 0.
In the case of 2% by weight, (c) is the case of 0.03% by weight. From this figure, it can be seen that when Nb2O5 is added and CaO is 0.04% by weight or more, the power loss is considerably reduced. It should be noted that if the CaO content exceeds 0.2% by weight, the ferrite sintered body will be insufficiently sintered, which is not preferable.

Figure 2 shows the effect of adding Nb2O5 to mackerel when CaO was 0.075% by weight and S i O2 was used as a parameter.

In the figure, curve (d) is when S i O2 is 0.018% by weight, (e) is 0.021% by weight, and (f) is 0.025%.
The case is shown below. From this figure, power loss is considerably reduced especially when N b 20 s is in the range of 0.02 to 0.05%. However, if N b 20 s is more than 0.1% by weight, the induced magnetic properties such as non-uniform crystal grain growth will deteriorate.

Note that if 5in2 is also more than 0.05% by weight, non-uniform crystal grain growth will occur and the light magnetic properties will deteriorate. Moreover, if CaO is less than 0.04% by weight, the specific resistance of the sintered body becomes too low and the frequency characteristics deteriorate. Furthermore, when Nb2O and 5in2 are not added, sufficient crystal grains cannot be obtained, and the magnetic properties also deteriorate.

Figure 3 shows the frequency characteristics of power loss, where the solid line (G) is for Example 1 of the present invention, and the dotted line (H) is for the existing material without adding Nb and Ol (corresponding to Comparative Example 1). Indicate the case.

From this figure, the example is considerably superior in the practical frequency range.

FIG. 4 shows the temperature characteristics of power loss. In this diagram,
The solid line (su) is for Example 1, and the dotted line (nu) is for the existing material. It can be seen from this figure that the power loss at around 80°C is considerably reduced.

As explained above, according to the ultra-low loss 7elite for power supply of the present invention, MnO, Zn0=Fe20- are the main components,
Since 0.04-0.2% by weight of CaO, 0.1% by weight or less of Nb2O5 and 0.05% by weight or less of SiO2 without containing O were added as subcomponents, In particular, power loss around 60 to 806C can be extremely reduced. Therefore, if used in a magnetic core that has a high magnetic flux density and generates heat during use, such as a transformer for a DC-DC converter, it will have a great effect, and the output can be improved by about 15% compared to the existing material with the same shape. given name.

[Brief explanation of the drawing]

Figure 1 is a graph showing the effect of Ca addition on power loss, Figure 2 is a graph showing the effect of Nb2O addition, Figure 3 is a graph showing frequency characteristics of power loss, and Figure 4 is a graph showing temperature characteristics. It is. Patent applicant Tokyo Denki Kagaku Kogyo Co., Ltd. Patent attorney Takashi Murai

Claims (1)

[Claims] (1) The main components are MnO, ZnO, and Fe20s, CaO is 0.04 to 0.2% by weight, Nb2O5 is 0.1% by weight or less, and 5in2 is 0% without O.
．． Ultra-low loss 7 element for power supply characterized by containing 0.05% by weight or less as a composite additive as an auxiliary component.