1 to the second outer magnetic core 2, and also includes a direction from the second outer magnetic core 2 to the first outer magnetic core 1.

The first outer magnetic core 1 may include a first base 11 and two first side columns 12. The two first side columns 12 are fastened to the first base 11, and the two first side columns 12 extend towards the second outer magnetic core 2. Correspondingly, the second outer magnetic core 2 may include a second base 21 and two second side columns 22. The two second side columns 22 are fastened to the second base 21, and the two second side columns 22 extend towards the first outer magnetic core 1. In an implementation, the two first side columns 12 and the two second side columns 22 are connected through fitting in a one-to-one correspondence, and the first side column 12 may be connected to the corresponding second side column 22 in a fixed manner like bonding or clamping. The first base 11 and the two first side columns 12 in the first outer magnetic core 1 may be of an integrated structure, and the second base 21 and the second side columns 22 in the second outer magnetic core 2 may be of an integrated structure. In another implementation, the first side column 12 and the corresponding second side column 22 may be integrated, the first base 11 and the first side column 12 may be connected in a fixed manner like bonding or clamping, and the second base 21 and the second side column 22 may be connected in a fixed manner like bonding or clamping. It should be understood that, in this embodiment, there may be a gap at a joint between the first side column 12 and the second side column 22, a joint between the first base 11 and the first side column 12, and a joint between the second base 21 and the second side column 22. It may be understood that the first outer magnetic core 1 and the second outer magnetic core 2 in the accompanying drawings of embodiments are merely examples, and the first outer magnetic core 1 and the second outer magnetic core 2 may be any one of an EE type magnetic core, an EP type magnetic core, a PQ type magnetic core, or an RM type magnetic core. A material of the first outer magnetic core 1 and the second outer magnetic core 2 may be a ferromagnetic body or a ferromagnetic powder or may be another ferric oxide mixture like ferro-silicon-aluminum.

FIG. 3b is a schematic diagram of a structure of an inductor according to an embodiment. For case of display, a coil winding 6 of the inductor is hidden in the figure. As shown in FIG. 3b, a winding unit R includes a magnetic core middle column 3 and at least two air-gaps. An axis of the magnetic core middle column 3 is parallel to the first direction. In an example, the at least two air-gaps are one air air-gap 41 and at least one solid air-gap 42. Still as shown in FIG. 3b, two ends that are of the magnetic core middle column 3 and that are in the first direction respectively fastened to a first base 11 and a second base 21. The magnetic core middle column 3 may be divided into at least three segments in the first direction, to form at least three inner magnetic cores (for example, a first inner magnetic core 31a, a second inner magnetic core 31b, and a third inner magnetic core 31c). The first inner magnetic core 31a is fastened to the first base 11, and the first inner magnetic core 31a and the first base 11 may be of an integrated structure. The third inner magnetic core 31c is fastened to the second base 21, and the third inner magnetic core 31c and the second base 21 may be of an integrated structure. The second inner magnetic core 31b is disposed between the first inner magnetic core 31a and the third inner magnetic core 3c. The solid air-gap 42 is disposed between the first inner magnetic core 31a and the second inner magnetic core 31b, and the air air-gap 41 is disposed between the second inner magnetic core 31b and the third inner magnetic core 31c. The air air-gap 41 and the solid air-gap 42 herein can implement segmentation of the magnetic core middle column 3, to reduce an eddy current loss generated by the coil winding wound around the magnetic core middle column 3. In another embodiment, the air air-gap 41 may be disposed between the first inner magnetic core 31a and the second inner magnetic core 31b, and the solid air-gap 42 may be disposed between the second inner magnetic core 31b and the third inner magnetic core 31c. It may be understood that the air air-gap 41 and the solid air-gap 42 may be disposed between any two adjacent inner magnetic cores. A material of the magnetic core middle column 3 may be a ferromagnetic body or a ferromagnetic powder or may be another ferric oxide mixture like ferro-silicon-aluminum. A material of the solid air-gap 42 may be a ferromagnetic body, or may be a ferromagnetic powder, or may be another ferric oxide mixture like ferro-silicon-aluminum.

FIG. 3c is a main view of an inductor according to an embodiment. For case of display, a coil winding 6 of the inductor is hidden in the figure. As shown in FIG. 3c, the first outer magnetic core 1 and the second outer magnetic core 2 are disposed opposite to each other in the first direction. The first outer magnetic core 1 includes the first base 11 and the two first side columns 12 connected to two sides of the first base 11, and the second outer magnetic core 2 includes the second base 21 and the two second side columns 22 connected to the second base 21. The winding unit R includes the magnetic core middle column 3, the air air-gap 41, and the solid air-gap 42. The magnetic core middle column 3 includes a first sub-column 3a and a second sub-column 3b, the first sub-column 3a is fastened to the first base 11, and the second sub-column 3b is fastened to the second base 21. The air air-gap 41 is disposed between the first sub-column 3a and the second sub-column 3b, and the solid air-gap 42 is disposed on the first sub-column 3a. It may be understood that the air air-gap 41 divides the magnetic core middle column 3 into the first sub-column 3a (such as the first inner magnetic core 31a and the second inner magnetic core 31b) and the second sub-column 3b (such as the third inner magnetic core 31c). The magnetic core middle column 3 includes the first inner magnetic core 31a, the second inner magnetic core 31b, and the third inner magnetic core 31c in the first direction. The first inner magnetic core 31a is fastened to the first base 11, and the third inner magnetic core 31c is fastened to the second base 21. The second inner magnetic core 31b is disposed between the first inner magnetic core 31a and the third inner magnetic core 3c. The air air-gap 41 is disposed between the second inner magnetic core 31b and the third inner magnetic core 31c. The solid air-gap 42 is disposed between the first inner magnetic core 31a and the second inner magnetic core 31b. It may be understood that the second inner magnetic core 31b is located between the air air-gap 41 and the solid air-gap 42.

As shown in FIG. 4, the first outer magnetic core 1 and the second outer magnetic core 2 are disposed opposite to each other in the first direction. The first outer magnetic core 1 includes the first base 11 and the two first side columns 12 connected to the two sides of the first base 11, and the second outer magnetic core 2 includes the second base 21 and the two second side columns 22 connected to the second base 21. The magnetic core middle column 3 is connected between the first base 11 and the second base 21, and the magnetic core middle column 3 includes the first inner magnetic core 31a, the second inner magnetic core 31b, and the third inner magnetic core 31c in the first direction. A solid air-gap 42 is disposed between the first inner magnetic core 31a and the second inner magnetic core 31b. For a structure of the solid air-gap 42, refer to FIG. 5.

As shown in FIG. 5, a hollow region Q that penetrates through the solid air-gap 42 in the first direction is disposed in a center of the solid air-gap 42. In this embodiment, the hollow region Q is cylindrical, an orthographic projection that is of the hollow region Q and that is on the first outer magnetic core 1 or the second outer magnetic core 2 is a circle, and a center of the circle of the circular projection is located on the axis of the magnetic core middle column 3. The hollow region Q and the magnetic core middle column 3 are coaxial, that is, an axis of the hollow region Q is collinear with the axis of the magnetic core middle column 3. It may be understood that the hollow region Q may alternatively be in another shape. A circumferential surface of the solid air-gap 42 may be flush with a circumferential surface of the magnetic core middle column 3, so that the solid air-gap 42 can be aligned with the circumferential surface of the magnetic core middle column 3. This helps the coil winding 6 be disposed around the winding unit R.

A magnetic induction intensity is a quantity of magnetic induction lines that can pass through per unit area, and the unit area is perpendicular to the first direction shown in FIG. 4 and FIG. 5. Due to existence of the hollow region Q, a magnetic induction intensity of the solid air-gap 42 is greater than a magnetic induction intensity of the magnetic core middle column 3. When a current of the coil winding 6 is small, and a magnetic flux in the solid air-gap 42 is not saturated, the solid air-gap 42 performs a magnetic conduction function. In this case, a total air-gap of the magnetic core 10 is equivalent to the air air-gap 41. When a current of the coil winding 6 increases, and a magnetic flux in the solid air-gap 42 is saturated, the magnetic flux in the solid air-gap 42 attenuates rapidly, and the solid air-gap 42 functions as the air air-gap. In this case, a total air-gap of the magnetic core 10 is equivalent to a superposition of the air air-gap 41 and the solid air-gap 42. Herein, the solid air-gap 42 is equivalent to a magnetic closed ring, so that the solid air-gap 42 can reduce an eddy current loss that is generated due to a leakage flux and that is on a surrounding coil winding.

As shown in FIG. 6a, a structure of the magnetic core 10 is similar to a structure of the magnetic core 10 shown in FIG. 4. A difference lies in that the solid air-gap 42 in the magnetic core 10 shown in FIG. 6a is a pie shape, and a radial size (a size perpendicular to the first direction) of the solid air-gap 42 is less than a radial size of the magnetic core middle column 3. A smaller radial size makes the magnetic induction intensity of the solid air-gap 42 greater than the magnetic induction intensity of the magnetic core middle column 3. When the magnetic flux in the solid air-gap 42 is not in a saturation state, the solid air-gap 42 can perform the magnetic conduction function. When the magnetic flux in the solid air-gap 42 is saturated, the magnetic flux in the solid air-gap 42 attenuates rapidly, and the solid air-gap 42 functions as the air air-gap.

FIG. 6b is a schematic diagram of a solid air-gap in an inductor according to an embodiment. As shown in FIG. 6b, the solid air-gap 42 has a first surface a1 and a second surface a2 that are parallel to each other in the first direction, and a radial size of the first surface a1 is less than a radial size of the second surface a2. The radial size of the second surface a2 may be less than or equal to the radial size of the magnetic core middle column 3. It may be understood that an included angle may alternatively be formed between the first surface a1 and the second surface a2, that is, the first surface a1 is not parallel to the second surface a2.

FIG. 6c is a schematic diagram of a solid air-gap in an inductor according to an embodiment. As shown in FIG. 6c, the solid air-gap 42 has a first surface a1 and a second surface a2 in the first direction, and an included angle is formed between the first surface a1 and the second surface a2, that is, the first surface a1 is not parallel to the second surface a2. A radial size of the second surface a2 may be less than the radial size of the magnetic core middle column 3.

As shown in FIG. 5 and FIG. 6b, a structure of the solid air-gap 42 may alternatively be shown in FIG. 7a. The solid air-gap 42 has the first surface a1 and the second surface a2 that are parallel to each other. The solid air-gap 42 has the hollow region Q that penetrates through the first surface a1 and the second surface a2. In the first direction, the radial size of the first surface a1 is less than the radial size of the second surface a2, and the radial size of the second surface a2 may be less than the radial size of the magnetic core middle column 3. It may be understood that an included angle may alternatively be formed between the first surface a1 and the second surface a2, that is, the first surface a1 is not parallel to the second surface a2.

As shown in FIG. 5 and FIG. 6c, a structure of the solid air-gap 42 may alternatively be shown in FIG. 7b. The solid air-gap 42 has the first surface a1 and the second surface a2, and an included angle is formed between the first surface a1 and the second surface a2. In the first direction, the solid air-gap 42 has the hollow region Q that penetrates through the first surface a1 and the second surface a2. In this implementation, the radial size of the second surface a2 of the solid air-gap 42 may be less than or equal to the radial size of the magnetic core middle column 3.

It should be understood that the foregoing embodiment merely describes the structure of the solid air-gap 42 by using simple examples. The structure of the solid air-gap 42 may be implemented in another manner, for example, a cube, a polyhedron, or even an irregular shape, provided that the magnetic induction intensity of the solid air-gap 42 is greater than the magnetic induction intensity of the magnetic core middle column 3. In this way, the solid air-gap 42 performs the magnetic conduction function or the functions of the air air-gap when the magnetic flux varies.

FIG. 8 is a main view of an inductor according to an embodiment. For case of display, the coil winding 6 of the inductor is hidden in the figure. As shown in FIG. 8, the first outer magnetic core 1 and the second outer magnetic core 2 are disposed opposite to each other in the first direction. The first outer magnetic core 1 includes the first base 11 and the two first side columns 12 connected to the two sides of the first base 11, and the second outer magnetic core 2 includes the second base 21 and the two second side columns 22 connected to the second base 21. The magnetic core middle column 3 is connected between the first base 11 and the second base 21. The magnetic core middle column 3 includes the first inner magnetic core 31a and the second inner magnetic core 31b in the first direction. The first inner magnetic core 31a is fastened to the first base 11, and the second inner magnetic core 31b is fastened to the second base 21. The air air-gap 41 is adjacent to the solid air-gap 42, and is disposed between the first inner magnetic core 31a and the second inner magnetic core 31b. The solid air-gap 42 is disposed on a side that is of the second inner magnetic core 31b and that faces the first inner magnetic core 31a, the second surface a2 of the solid air-gap 42 is fastened to a surface that is of the second inner magnetic core 31b and that faces the first inner magnetic core 31a, and the air air-gap 41 is disposed between the solid air-gap 42 and the first inner magnetic core 31a. It may be understood that the solid air-gap 42 may alternatively be disposed on a side that is of the first inner magnetic core 31a and that faces the second inner magnetic core 31b, the second surface a2 of the solid air-gap 42 is fastened to a surface that is of the first inner magnetic core 31a and that faces the second inner magnetic core 31b, and the air air-gap 41 is disposed between the solid air-gap 42 and the second inner magnetic core 31b.

FIG. 9 is a schematic diagram of a distribution of magnetic induction lines of an inductor according to an embodiment. For case of display, the coil winding 6 of the inductor is hidden in the figure. For case of display, only three groups of magnetic induction lines are used as an example herein by using dashed lines, and arrow directions are merely an example. As shown in FIG. 9, after the coil winding 6 of the winding unit R is powered on, a plurality of magnetic induction lines pass through the magnetic core middle column 3 and the solid air-gap 42. Magnitude of the current of the coil winding 6 is positively correlated with the magnetic flux in the magnetic core 10 within a range. Therefore, when the current of the coil winding 6 increases, the magnetic flux in the magnetic core middle column 3 and the magnetic flux in the solid air-gap 42 increases accordingly. As described in the foregoing embodiment, the magnetic induction intensity of the solid air-gap 42 is less than the magnetic induction intensity of the magnetic core middle column 3. As the current of the coil winding 6 increases, the solid air-gap 42 is to be in a magnetic flux saturation state earlier than the magnetic core middle column 3. When the magnetic flux in the solid air-gap 42 is saturated, the magnetic flux in the solid air-gap 42 attenuates rapidly, and the solid air-gap 42 functions as the air air-gap. In other words, when the current of the coil winding 6 is small, the magnetic flux of the solid air-gap 42 is not saturated. Because the material of the solid air-gap 42 is a magnetic material, the solid air-gap 42 can perform the magnetic conduction function as the magnetic core middle column 3. In this case, a size of the total air-gap of the inductor is equal to a size of the air air-gap 41. When the current of the coil winding 6 increases, and the magnetic flux in the solid air-gap 42 is saturated, the magnetic flux in the solid air-gap 42 attenuates rapidly, and the solid air-gap 42 functions as the air air-gap. In this case, a size of the total air-gap of the inductor is equal to a superposition of a size of the air air-gap 41 and a size of the solid air-gap 42. The total air-gap of the inductor increases, and the inductance of the inductor decreases. It may be understood that the solid air-gap 42 of the inductor provided in this embodiment can perform the magnetic conduction function or the function of the air-gap as the magnetic flux varies. Therefore, the total air-gap of the inductor can vary as the current of the coil winding 6 varies, so that the inductance of the inductor can vary as the current of the coil winding 6 varies.

FIG. 10a and FIG. 10b each are a main view of an inductor according to an embodiment. For case of display, the coil winding 6 of the inductor is hidden in the figure. As shown in FIG. 10a and FIG. 10b, the first outer magnetic core 1 and the second outer magnetic core 2 are disposed opposite to each other in the first direction. The first outer magnetic core 1 includes the first base 11 and the two first side columns 12 connected to the two sides of the first base 11, and the second outer magnetic core 2 includes the second base 21 and the two second side columns 22 connected to the second base 21. The magnetic core middle column 3 may be fixedly connected to the first outer magnetic core 1 or the second outer magnetic core 2, and the air air-gap 41 may be formed between the magnetic core middle column 3 and the first outer magnetic core 1 or between the magnetic core middle column 3 and the second outer magnetic core 2. In FIG. 10a, the magnetic core middle column 3 includes the first inner magnetic core 31a and the second inner magnetic core 31b that are sequentially distributed in the first direction. The first inner magnetic core 31a is fastened to the first base 11 of the first outer magnetic core 1, the solid air-gap 42 is disposed between the first inner magnetic core 31