JPH03145704A - Low loss oxide magnetic material - Google Patents

Abstract

PURPOSE:To obtain a magnetic material, having low power loss and exothermic temperature can be suppressed to the limit or lower even when a frequency of 200kHz or higher is used by a method wherein a specific quantity of Nb2O5 is contained in a low-loss oxide magnetic material containing MnO, ZnO and Fe2O3 as the main ingredients and also containing a specific quantity of CaO and SiO2 as the auxiliary ingredients. CONSTITUTION:Nb2O5 of 0.05wt.% or less is contained in the conventional low loss oxide magnetic material containing MnO of 30 to 37mol%, ZnO of 10 to 15mol%, and the remaining part consisting of Fe2O3 as the main ingredients of oxide magnetic material formed by mixing, molding and calcinating oxide powder, and also containing CaO of 0.04 to 0.10wt.% and SiO2 of 0.015 to 0.100wt.% as auxiliary ingredients. Power loss characteristics have the minimum value at about 60 deg.C, which is the neighborhood of a practical temperature, irrespective of presence or non-presence of Nb2O5. With the increase of the content of Nb2O5, the power loss characteristics become small, the loss characteristics 4 becomes the smallest when the content of Nb2O5 is 0.015wt.%, and the power loss becomes larger than the loss characteristics 1 containing no Nb2O5 when its content exceeds the loss characteristics 7 shown in the diagram mentioned separately.

Description

Detailed Description of the Invention A. Object of the Invention [Field of Industrial Application] The present invention relates to a low-loss oxide magnetic material used as a core material for switching power supplies used in electronic devices and other transformers used at high frequencies. .

[Conventional technology]

In conventional transformers for switching power supplies used in electronic equipment, the switching frequency is exclusively 25 to 2O0.
kHz, and the low-loss oxide magnetic material that is the core material for transformers to accommodate this is manganese monoxide (Mn), whose main component is 30 to 37 mol%.
O), 10 to 15 mol% of zinc oxide (ZnO) and ferric oxide (Fe2O:+) as the remainder, and calcium oxide (CaO
) and 0.015 to 0.100% by weight of silicon dioxide (
Low-loss oxide magnetic materials containing Si02) have already been developed and used.

[Problem to be solved by the invention]

However, in recent years, it has become common for switching power supplies to use high switching frequencies of 200 KHz or higher in order to make them smaller and lighter. However, when a conventional low-loss oxide magnetic material having the above-mentioned components is used as a core material of a transformer for a switching power supply with a switching frequency of 200KHz or higher, the power loss of the core material (PI] [KW/m3]) This has the drawback that it cannot withstand use because it generates heat above the practical temperature and may burn out the transformer itself located in the switching power supply and parts in its vicinity.

Therefore, an object of the present invention is to provide a low-loss oxide magnetic material that can be used practically even when used at a high frequency of 200 KHz or higher, with low power loss and suppressed heat generation temperature below the limit. It is in.

1. Structure of the invention [Means for solving the problem] The present invention provides 30 to 37 mol% manganese monoxide (MnO ), 10-15 mol% zinc oxide (Z
nO), and ferric oxide (Fe2O3) as a balance, and contains 0.04-0.10% by weight of calcium oxide (CaO) and 0.015-0.100% by weight of silicon dioxide ( In the low-loss oxide magnetic material containing SiO2), the low-loss oxide magnetic material contains 0 to 0.0
50% by weight (excluding 0%) of niobium oxide (Nb2
This is a low-loss oxide magnetic material characterized by containing O5).

[Effect]

In order to suppress the heat generation of transformers used in switching power supplies and other high-frequency devices, the operating frequency (here, 200 KHz or higher) of the oxide magnetic material that is the core material of the transformer is required.
) and the power loss (P, [K″W/m3]) at the operating temperature (generally 40-80°C).

Therefore, in the present invention, various amounts of niobium oxide (Nb2O5) are added to the conventional oxide magnetic material consisting of the two components, and the frequency of the oxide magnetic material obtained through this series of experiments is determined. The relationship between temperature and power loss at frequencies below 200 KHz was investigated in detail, and as a result, the above-mentioned oxide magnetic material of the present invention was obtained. An example of the obtained low-loss oxide magnetic material, which contains 0.015% niobium oxide (Nb2Os) in addition to the conventional components, has a power loss p at 500K)Iz and 60℃, for example.
b was 95 KW/m3, which was reduced to about 60% of that of the conventional material, and it was confirmed that this is a low-loss oxide magnetic material that can be fully used in practical use at a high frequency of 500 KHz.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. In order to obtain a low-loss oxide magnetic material with further reduced power loss at high frequencies of 200KHz or higher, which is the object of the present invention, niobium oxide (Nb2O5 ) was conducted, which will be explained next.

That is, the main components of an oxide magnetic material made by mixing, molding, and firing oxide powders include the conventional components of 30 to 37 mol% manganese monoxide (MnO) and 10 to 15 mol% zinc oxide (ZnO). ), and the remainder is ferric oxide (Fe2O3
), and the subcomponents are conventional components 0, 04 to 0.
．． 10% by weight of calcium oxide (CaO) and 0.01
A conventional low-loss oxide magnetic material containing silicon dioxide (SiO2) in an amount of 5 to 100% by weight is further added with niobium oxide (Nb2O5) as an additive in the range of 0 to 0.07% by weight (however, 0%). Six types of new low-loss oxide magnetic materials containing niobium oxide were prepared and used as samples of Examples 1 to 6, and a conventional low-loss oxide magnetic material containing no niobium oxide was prepared and compared. This was used as an example sample. In preparing the following seven types of samples, all the same oxide powder raw materials were used, and mixing, molding, and firing were performed under the same conditions as those for manufacturing conventional low-loss oxide magnetic materials. The standard shape of the samples was all ring cores with an outer diameter of 36φmm, an inner diameter of 24φmm, and a height of 8mm.

Here, the niobium oxide (Nb2.05) contents of the duplicate comparative examples and the samples of Examples 1 to 6 are as follows.

Comparative example... Niobium oxide content Example 1... Niobium oxide content Example 2... Niobium oxide content Example 3 W' l, niobium content Example 4... Niobium oxide content o, ooo weight% 0,005 weight% 0,010 weight% 0,015 weight% 0.030 weight% Example 5... Niobium oxide content 0.050 weight% Example 6... Niobium oxide content Power loss (PB [KW/m3]) at high frequency (200KHz or more) was tested for seven types of samples containing 0.070% by weight or more.

Figure 1 shows the frequency of 500 for the seven types of samples mentioned above.
Power loss (PR [KW/m'l) with respect to the sample temperature T (°C) when the content of niobium oxide (Nb2O5) is a parameter under the test conditions described in "KHz, maximum magnetic flux density is 500 Gauss" FIG. 2 is a temperature-power loss characteristic diagram showing

Each of the curves shown in FIG.
Power loss characteristics 1 of conventional comparative example that does not contain b2O5)
(indicated by the dashed line) and 0.005% by weight of niobium oxide (N
Power loss characteristics 2 of Example 1 containing b2O5) and 0
．． Power loss characteristic 3 of Example 2 containing 0.010 wt% niobium oxide (Nb2O5), power loss characteristic 4 of Example 3 containing 0.015 wt% niobium oxide (Nb2O5), and 0.030 wt. % niobium oxide (Nb2O5)
power loss characteristic 5 of Example 4 containing 0.050 wt.% niobium oxide (Nb2O5), power loss characteristic 6 of Example 5 containing 0.050 wt.
Fig. 7 shows the power loss characteristic 7 of Example 6 containing b2Os).

From FIG. 1, each of the power loss characteristics 1 to 7 has a minimum value when the temperature is about 60° C., near the practical temperature, regardless of whether niobium oxide (Nb2O5) is contained. As the content of niobium oxide (Nb2O5) increases, the power loss characteristics become smaller, and when the content is 0.0
Power loss characteristic 4 of Example 3 is the smallest when the content is 15% by weight, and as the content increases beyond that, the power loss (PB [KW/m3F) increases, and when the content is 0. When the content exceeds 0.050% by weight, as shown in power loss characteristic 7 of Example 6, the power loss becomes larger than that of the comparative example that does not contain it at all. This allows niobium oxide (N
It can be seen that those containing 0 to 0.050% by weight (not including 0%) of b2O5) have smaller power loss and therefore generate less heat than those that do not contain it.

Incidentally, this tendency of decrease and increase in power loss due to the content of niobium oxide (Nb2O5) is observed as the switching frequency increases to 2.
It was also confirmed that the maximum magnetic flux density Bm did not change within the range of O0 to 500KHz and up to 2000G.

Table 1 shows the magnetic properties [initial permeability μm, saturation magnetic flux Density B15 (magnetic flux density at magnetizing force 150e) [G
], residual magnetic flux density Br [G], coercive force He [Oel
] A comparison of the evaluation results is shown. The magnetic properties of Example 3 are almost the same as those of the conventional comparative example, and it is found to be excellent in terms of initial magnetic permeability, saturation magnetic flux density, etc. as a low-loss oxide magnetic material for transformer and dexterity. It shows. Although not described, evaluations of other examples showed similar characteristics, and it was confirmed that these were excellent low-loss oxide magnetic materials containing the same series as the main component.

As is clear from FIG. 1 and Table 1, Examples 1 to 5 of the present invention have better power loss as core materials for high-frequency switching power supplies than conventional comparative examples, and fully satisfy the required magnetic properties. are doing.

By the above table 1, niobium oxide (Nb2O5) is 0 to 0.
The oxide magnetic material containing 0.050% by weight (excluding 0%) is superior to conventional materials as a core material for transformers for switching power supplies of 200 KHz or higher. In Example 3 containing % by weight, compared with the comparative example not containing it, at a frequency of 500 KHz, a magnetic flux density of 500 G, and a temperature of 60°C, the
It can be seen that the power loss has been improved by 0%, and it is a low-loss oxide magnetic material with good characteristics at high frequencies of 200 KHz or higher.

C. Effects of the Invention [Effects of the Invention] As detailed above, according to the present invention, it is possible to reduce zero power loss at high frequencies of 200 KHz or higher, which is particularly necessary as a core material of transformers for high frequency switching power supplies. Therefore, it is possible to provide an excellent low-loss oxide magnetic material that suppresses heat generation and can be put to practical use.

[Brief explanation of the drawing]

FIG. 1 shows samples of low-loss oxide magnetic materials of Examples 1 to 6 of the present invention and comparative examples at a frequency of 500 KHz,
When the content of niobium oxide (Nb2O5) is used as a parameter under the test conditions of maximum magnetic flux density of 500 Gauss,
Power loss (PB[KW/
FIG. 1... Power loss characteristics of comparative example, 2... Power loss characteristics of Example 1, 3... Power loss characteristics of Example 2, 4...
- Power loss characteristics of Example 3, 5... Power loss characteristics of Example 4, 6... Power loss characteristics of Example 5, 7... Power loss characteristics of Example 6.

Claims (1)

[Claims] 1. The main components of the oxide magnetic material made by mixing, molding, and firing oxide powders include 30 to 37 mol% manganese monoxide (MnO) and 10 to 15 mol% zinc oxide (ZnO).
, and contains ferric oxide (Fe_2O_3) as a balance, and 0.04-0.10% by weight of calcium oxide (CaO) and 0.015-0.100% by weight of silicon dioxide (SiO_2) as accessory components. In the low-loss oxide magnetic material containing 0 to 0.0 in the low-loss oxide magnetic material,
50% by weight (excluding 0%) of niobium oxide (Nb_
A low-loss oxide magnetic material characterized by containing 2O_5).