Patent Application
20180261375
The present invention relates to a magnetic core capable of preventing fast direct current (DC) saturation attenuation and a manufacturing method thereof, and particularly to a magnetic core formed as a sintered integral comprising a center column having a lower magnetic permeability and a manufacturing method thereof.
In many applications, an inductor needs to receive a relatively high direct current (DC), e.g., a 10 A current. In addition to a high DC current, an inductor may also need to operate at a high operating frequency. However, an inductor is formed by a coil of at least one turn, and a magnetic core (or referred to as an iron magnetic core) that generally has one single magnetic permeability. When the inductor is employed in a high DC current application, once the magnetic core becomes saturated, the overall performance of the inductor may attenuate to result a negative effect in the application.
Therefore, a power inductor for reducing the saturation of a DC current is disclosed. For example, the Taiwan Patent Publication No. 1333220 discloses a power inductor. In one embodiment of the above disclosure, the power inductor includes a first magnetic core and a second magnetic core. The second magnetic core has a lower magnetic permeability than that of the first magnetic core, so as to achieve the object of reducing the DC current saturation. However, from the disclosure of paragraphs 3 to 4 on page 14 of the specification, it is learned that the first magnetic core and the second magnetic core, instead of being integrally formed by sintering, are first separately manufactured and then connected. Further, such connection undesirably affects the overall structural strength and characteristics of the overall structure.
It is an object of the present invention to solve the issue of fast attenuation when the current reaches saturation for a conventional magnetic core in overall having only one magnetic permeability after the magnetic core is sintered.
To achieve the above object, the present invention provides a magnetic core capable of preventing fast direct current (DC) saturation attenuation. The magnetic core is a sintered integral, and includes a center column, two side columns and a base. Each of the side columns is disposed at a distance from the center column, and is parallel to the center column. The base is connected to the center column and the two side columns. The center column has a first magnetic permeability, and the two side columns have a second magnetic permeability, with the first magnetic permeability being smaller than the second magnetic permeability. The base includes a first connecting portion connected to the center column, two second connecting portions respectively connected to the side columns, and two first wing portions extended from the first connecting portion and respectively connected to the second connecting portions. The first connecting portion and the first wing portions have the first magnetic permeability, and the second connecting portions have the second magnetic permeability.
In one embodiment, the base includes two second wing portions respectively extended from the two side columns and respectively connected to the first wing portions. The two second wing portions have the second magnetic permeability.
The present invention further provides a method for manufacturing a magnetic core capable of preventing fast DC saturation attenuation. The method includes following steps.
In an initialization step, a mold including a mold cavity is provided, a first feeding opening is disposed at a center column forming portion of the mold cavity, and a second feeding opening is formed at each of two side column forming portions in the mold cavity.
In a feeding step, a material is fed into the mold cavity through the first feeding opening and the second feeding openings, such that a first magnetic material is fed to the center column forming portion through the first feeding and a second magnetic material is fed to the side column forming portions through the respective second feeding openings. Further, the first magnetic material fed in is contact with the second magnetic material in the mold cavity, and the first magnetic material and the second magnetic material are the same material, with however the magnetic permeability of the first magnetic material being smaller than the magnetic permeability of the second magnetic material.
In a sintering step, a sintering process is performed on the mold, to cause the first magnetic material and the second magnetic material fed into the mold cavity to be integrally sintered into the magnetic core. The magnetic core includes the center column formed by the first magnetic material, the two side columns formed by the second magnetic material, and the base. The base is connected to the center column and the two side columns. The center column has the first magnetic permeability, and the two side columns have the second magnetic permeability, with the first magnetic permeability being smaller than the second magnetic permeability. The base includes the first connecting portion connected to the center column, the two second connecting portions respectively corresponding to the two side columns, and the two first wing portions extended from the first connecting portion and respectively connected to the two second connecting portions. The first connecting portion and the first wing portions have the first magnetic permeability, and the second connecting portions have the second magnetic permeability.
In one embodiment, in the sintering step, the base includes two second wing portions respectively extended from the side columns and respectively connected to the first wing portions. The second wing portions have the second magnetic permeability.
In one embodiment, the first magnetic material and the second magnetic material are ferrites.
Through the embodiments of the present invention, the magnetic core of the present invention provides following features compared to a conventional solution. The magnetic core is an integral formed by sintering, and has a first magnetic permeability and a second magnetic permeability. Compared to a conventional solution, the present invention is capable of preventing fast DC saturation attenuation. Further, in addition to forming the center column of the magnetic core of the present invention by the first magnetic material, the first magnetic material is further used to form the first connecting portion and the two first wing portions of the base, thereby preventing breakage of the center column of the magnetic core after the sintering process.
Details and technical contents of the present invention are given with the accompanying drawings below.
Referring to
In addition to an E-type magnetic core, the magnetic core 10 of the present invention may also be implemented by a PQ-type magnetic core, as shown in
Referring to
In an initialization step 30, the mold 20 including a mold cavity 201 is provided, a first feeding opening 21 is disposed at a center column forming portion 202 in the mold cavity 201, and a second feeding opening 22 is disposed at each of two side column forming portions 203 in the mold cavity 201.
In a feeding step 31, a material is fed into the mold cavity 201 through the first feeding opening 21 and the second feeding openings 22, such that a first magnetic material 40 is fed to the center column forming portion 202 through the first feeding opening 21 and a second magnetic material 41 is fed to the side column forming portions 203 through the respective second feeding openings 22. Further, the first magnetic material 40 fed in is contact with the second magnetic material 41 in the mold cavity 201, and the first magnetic material 40 and the second magnetic material 41 are the same material, with however the magnetic permeability of the first magnetic material 40 being smaller than the magnetic permeability of the second magnetic material 41.
In a sintering step 32, a sintering process is performed on the mold 20, to cause the first magnetic material 40 and the second magnetic material 41 fed into the mold cavity 201 to be integrally sintered into the magnetic core 10. The magnetic core 10 includes the center column 11 formed by the first magnetic material 40, the two side columns 12 formed by the second magnetic material 41, and the base 13. The base 13 is connected to the center column 11 and the two side columns 12. The center column 11 has the first magnetic permeability, and the two side columns 12 have the second magnetic permeability, with the first magnetic permeability being smaller than the second magnetic permeability. The base 13 includes the first connecting portion 131 connected to the center column 11, the two second connecting portions 132 respectively corresponding to the two side columns 12, and the two first wing portions 133 extended from the first connecting portion 131 and respectively connected to the two second connecting portions 132. The first connecting portion 131 and the first wing portions 133 have the first magnetic permeability, and the second connecting portions 132 have the second magnetic permeability.
More specifically, in one embodiment of the present invention, the mold 20 may be divided into a lower mold body 204 and an upper mold body 205. The lower mold body 204 includes the mold cavity 201, and the upper mold body 205 includes the first feeding opening 21 and the two second feeding openings 22 corresponding to the mold cavity 201. Further, the first feeding opening 21 is connected to a first feeding channel 206, and each of the second feeding openings 22 is connected to a second feeding channel 207. In the present invention, each of the first feeding channel 206 and the two second feeding channels 207 is connected to a feed control module (not shown), and the material is provided through one of the feed control modules connected. More specifically, one of the feed control modules connected to the first feeding channel 206 provides the first feeding channel 206 with the first magnetic material 40, and another feed control module connected to the second feeding channel 207 provides the second feeding channel 207 with the second magnetic material 41. Further, details of the control of the feed control modules are generally known to one person skilled in the art, and shall be omitted herein. In one embodiment, the first magnetic material 40 and the second magnetic material 41 are ferrite powder, with however the magnetic permeabilities of the two being different.
In continuation, in the feeding step 31 of the method, the upper mold body 205 is correspondingly stacked on the lower mold body 204, and the material is fed into the mold cavity 201 through the first feeding opening 21 and the second feeding opening 22. That is to say, the material control modules provide the material to the first feeding channel 206 and the second feeding channels 207, respectively. At this point, the first magnetic material 40 is fed to the center column forming portion 202 of the mold cavity 201 through the first feeding opening 21, and the second magnetic material 41 is fed to the two side column forming portions 203 in the mold cavity 201 through two second feeding channels 22. When the material fed satisfies a predetermined condition, the feeding process is terminated, and the sintering step 32 is then performed. In the sintering step 32, the mold 20 is heated or pressurized to perform sintering, to cause the first magnetic material 40 and the second magnetic material 41 in the mold cavity 201 to be integrally sintered into the magnetic core 10. A mold removal process is next performed.
In one embodiment, in the sintering step 32, feeding parameters of these feed control modules may be controlled, in a way that, in addition to being fed to the center column forming portion 202 or the two side column forming portions 203, the first magnetic material 40 and the second magnetic material 41 are further overflowed to the part of the mold cavity 201 where the base 13 is to be formed, as shown in
In one comparison experiment, a ferrite KP44A is implemented as a conventional magnetic core to be compared with the magnetic core 10 disclosed by the present invention. In the magnetic core 10 of the present invention, the first magnetic material 40 is implemented by a ferrite KP50 and the second magnetic material 41 is implemented by a ferrite KP44A. Further, each of the conventional magnetic core and the magnetic core 10 of the present invention is made into an inductor using the same winding parameter, a power test using a fixed voltage (1V) and a constant frequency (100 kHz) is performed, and the current (I) is gradually increased during the power test.
