DC-DC converter and power source circuit

Abstract

To provide a DC-DC converter and a power source circuit in which performance improvement and downsizing are achieved.SOLUTION: In a DC-DC converter 200 of a power source circuit 100, coil inductors 3A, 3B of an inductance element 1 including, as a core, a magnetic block 2 formed of magnetic thin bands 22 where no crack substantially occurs are used as inductors L1, L2. Accordingly, the performance can be improved from the viewpoint of loss reduction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a DC-DC converter and a power supply circuit. [Background technology]

[0002] Cited Document 1 discloses an inductor including a coil conductor and a magnetic core. The magnetic core disclosed in this document has a laminated structure in which magnetic ribbons made of an amorphous alloy or a nanocrystalline alloy are stacked. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-26401 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have conducted extensive research into the application of inductors with magnetic cores made of laminated magnetic ribbons to two-phase DC-DC converters, and as a result have discovered a new technology that can improve characteristics such as loss, inductance value, and DC superposition characteristics, as well as reduce the size.

[0005] An object of one aspect of the present disclosure is to provide a DC-DC converter and a power supply circuit with improved characteristics and reduced size. [Means for solving the problem]

[0006] a first circuit including a first capacitor and a first inductor connected in series in this order between the first switching element and the first output terminal, and a second switching element connected between the first capacitor and the first inductor; a second circuit including a fourth switching element connected in parallel to the first circuit between the first switching element and the first output terminal, and a third switching element and a second inductor connected in series in this order and connected between the third switching element and the second inductor; and a second capacitor connected between the first output terminal and the second output terminal, wherein at least one of the first inductor and the second inductor is an inductance element including a first coil conductor, a magnetic body juxtaposed to the first coil conductor, and a magnetic resin containing the first coil conductor and the magnetic body, and the magnetic body has a laminated structure in which a plurality of magnetic ribbons are stacked, and each magnetic ribbon is not divided into a plurality of small pieces by a crack.

[0007] A power supply circuit according to one aspect of the present disclosure includes the above DC-DC converter and an input power supply that inputs a DC voltage of 10 V or more between a first input terminal and a second input terminal of the DC-DC converter. [Effects of the Invention]

[0008] According to one aspect of the present disclosure, a DC-DC converter and a power supply circuit are provided that are improved in characteristics and are miniaturized. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a circuit diagram illustrating a power supply circuit according to an embodiment. [Figure 2] 2 is a perspective view showing an inductance element used in the DC-DC converter shown in FIG. 1. FIG. [Figure 3] FIG. 3 is an exploded view showing the inductance element shown in FIG. 2. [Figure 4]FIG. 3 is a diagram showing a layered structure of the magnetic block shown in FIG. [Figure 5] FIG. 1 is a circuit diagram showing a DC-DC converter without capacitor voltage division. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0011] First, with reference to FIG. 1, the circuit configuration of a power supply circuit 100 according to one embodiment will be described.

[0012] The power supply circuit 100 includes a DC-DC converter 200 and an input power supply 300 .

[0013] The DC-DC converter 200 is a two-phase step-down DC-DC converter. The DC-DC converter 200 has a pair of input terminals A1, A2 and a pair of output terminals B1, B2. The pair of input terminals A1, A2 is composed of a first input terminal A1 and a second input terminal A2. The pair of output terminals B1, B2 is composed of a first output terminal B1 and a second output terminal B2. The second input terminal A2 and the second output terminal B2 form a ground line.

[0014] A first switching element SW1 is connected to the first input terminal A1. A first circuit 201 and a second circuit 202 are connected in parallel between the first switching element SW and the first output terminal B1. The first circuit 201 includes a first capacitor C1 and a first inductor L1 connected in series, with the first capacitor C1 and the first inductor L1 arranged in that order from the side closest to the first switching element SW. A second switching element SW2, which is a diode, is connected in the reverse direction between the connection point between the first capacitor C1 and the first inductor L1 and the ground line. The second circuit 202 includes a third switching element SW3 and a second inductor L2 connected in series, with the third switching element SW3 and the second inductor L2 arranged in that order from the side closest to the first switching element SW1. A fourth switching element SW4, which is a diode, is connected in the reverse direction between the connection point between the third switching element SW3 and the second inductor L2 and the ground line. A second capacitor C2 is connected between the first output terminal B1 and the second output terminal B2.

[0015] The first switching element SW1 and the third switching element SW3 may be configured, for example, by transistors. The first switching element SW1 and the third switching element SW3 are alternately turned on and off by a control circuit (not shown), thereby generating an output voltage that is a step-down of the input voltage. In the DC-DC converter 200 of this embodiment, the first capacitor C1 divides the input voltage in half, thereby reducing switching loss and output voltage ripple. Therefore, the DC-DC converter 200 is a two-phase step-down DC-DC converter equipped with a capacitor voltage division function. Note that the second switching element SW2 and the fourth switching element SW4 may be configured by transistors instead of diodes.

[0016] The input power supply 300 is connected to a pair of input terminals A1 and A2 of the DC-DC converter 200, and inputs a DC voltage between the pair of input terminals A1 and A2. The voltage input from the input power supply 300 to the DC-DC converter 200 can be 10 V or higher.

[0017] Next, the inductance element 1 used for the two inductors L1 and L2 included in the DC-DC converter 200 will be described with reference to Figs. 2 and 3. Fig. 2 is a perspective view of the inductance element 1. Fig. 2 is a development view of the inductance element 1. Fig. 1 shows the inductance element 1 mounted on a substrate 11.

[0018] The inductance element 1 is configured to include an element body 90, and a magnetic block 2 and coil conductor 3 provided within the element body 90. The magnetic block 2, which forms the core, and the coil conductor 3 are layered in the X-axis direction.

[0019] As shown in Fig. 2, the inductance element 1 includes an element body 90 having a rectangular parallelepiped outer shape. In this embodiment, the outer shape of the element body 90 is formed by three pairs of surfaces that face each other in the X-axis direction, the Y-axis direction, and the Z-axis direction. The element body 90 can be made of magnetic resin. The magnetic resin is a resin that contains magnetic powder, and is, for example, a bound powder in which magnetic powder is bound by a binder resin.

[0020] The inductance element 1 includes an element body 90 and includes three magnetic blocks 2 and two coil conductors 3 therein.

[0021] The three magnetic blocks 2 are composed of a first magnetic block 2A, a second magnetic block 2B, and a third magnetic block 2C. The first magnetic block 2A, the second magnetic block 2B, and the third magnetic block 2C are arranged in this order, facing each other at a distance in the X-axis direction. The magnetic blocks 2 have a rectangular parallelepiped shape. In this embodiment, the magnetic blocks 2 have a flattened rectangular parallelepiped shape in the X-axis direction. The magnetic blocks 2 have the same shape. The magnetic properties of the magnetic blocks 2 may be substantially the same or different.

[0022] Each of the three magnetic blocks 2A to 2C has a pair of main surfaces 2a and 2b, a pair of end surfaces 2c and 2d, and a pair of side surfaces 2e and 2f. The pair of main surfaces 2a and 2b face each other in the X-axis direction. The main surface 2a is located on the negative side of the X-axis direction, and the main surface 2b is located on the positive side of the X-axis direction. The pair of end surfaces 2c and 2d face each other in the Y-axis direction. The end surface 2c is located on the positive side of the Y-axis direction, and the end surface 2d is located on the negative side of the Y-axis direction. The pair of side surfaces 2e and 2f face each other in the Z-axis direction. The side surface 2e is located on the positive side of the Z-axis direction, and the side surface 2f is located on the negative side of the Z-axis direction.

[0023] 1, the magnetic blocks 2A to 2C are arranged at the same position in the YZ plane so that their end faces and side faces overlap each other when viewed from the X-axis direction. Note that positional deviations within a range caused by manufacturing errors, etc., are considered to be included in the "same position."

[0024] As shown in FIG. 4, each magnetic block 2 includes multiple magnetic ribbons 22 (more specifically, ribbons made of a soft magnetic metal) stacked along the Z axis, and has a laminated structure in which the multiple magnetic ribbons 22 and multiple adhesive layers 24 are alternately arranged. The main surfaces 2a and 2b of each magnetic block 2 may be composed of the magnetic ribbons 22 or adhesive layers 24. The number of layers of the magnetic ribbons 22 constituting each magnetic block 2 is, for example, 120. The magnetic ribbons 22 are, for example, amorphous ribbons or nanocrystalline ribbons. The magnetic ribbons 22 may be composed of magnetic alloys such as amorphous alloys, microcrystalline alloys, permalloys, and alloys with nanoheterostructures. Amorphous alloy materials include Fe-based amorphous soft magnetic materials and Co-based amorphous soft magnetic materials, and microcrystalline alloys include Fe-based nanocrystalline soft magnetic materials. A nanoheterostructure refers to a structure in which microcrystals exist in an amorphous structure.

[0025] Each magnetic ribbon 22 constituting the magnetic block 2 is handled and stacked so as not to cause cracks. Therefore, each magnetic ribbon 22 has substantially no cracks. Even if a small crack occurs in each magnetic ribbon 22, such a crack does not divide the magnetic ribbon 22 into small pieces. Furthermore, even if a crack or chip occurs during the manufacturing process and a part of the magnetic ribbon 22 is divided, such a part does not correspond to a small piece divided by a crack.

[0026] The two coil conductors 3 are composed of a first coil conductor 3A and a second coil conductor 3B. The first coil conductor 3A and the second coil conductor 3B are arranged side by side along the X-axis direction, with the second magnetic block 2B in between. The first coil conductor 3A is disposed between the first magnetic block 2A and the second magnetic block 2B, and the second coil conductor 3B is disposed between the second magnetic block 2B and the third magnetic block 2C. The material of the coil conductor 3 is composed of a metal selected from, for example, Cu, Ag, Au, Al, Ni, Sn, etc.

[0027] The first coil conductor 3A includes a first conductor portion 4A, a second conductor portion 4B, a connecting portion 6, a first terminal portion 7A, and a second terminal portion 7B.

[0028] The conductors 4A and 4B both extend in the Z-axis direction and are parallel to each other. The conductors 4A and 4B are arranged between the first magnetic block 2A and the second magnetic block 2B in the X-axis direction. The first conductor 4A is arranged on the positive side of the Y-axis direction, and the second conductor 4B is arranged on the negative side of the Y-axis direction. The conductors 4A and 4B do not have to be parallel to the Z-axis direction as long as they extend in the Z-axis direction.

[0029] The first conductor portion 4A has a pair of opposing surfaces 4Aa, 4Ab and a pair of side surfaces 4Ac, 4Ad. The pair of opposing surfaces 4Aa, 4Ab face each other in the X-axis direction. The opposing surface 4Aa, located on the positive side of the X-axis direction, faces the first magnetic block 2A in the X-axis direction. The opposing surface 4Ab, located on the negative side of the X-axis direction, faces the second magnetic block 2B in the X-axis direction. The side surfaces 4Ac, 4Ad face each other in the Y-axis direction. The side surface 4Ac is located on the positive side of the Y-axis direction, and the side surface 4Ad is located on the negative side of the Y-axis direction. The second conductor portion 4B has a pair of opposing surfaces 4Ba, 4Bb and a pair of side surfaces 4Bc, 4Bd. The pair of opposing surfaces 4Ba, 4Bb face each other in the X-axis direction. The opposing surface 4Ba, located on the negative side of the X-axis direction, faces the first magnetic block 2A in the X-axis direction. The opposing surface 4Bb, located on the positive side of the X-axis direction, faces the second magnetic block 2B in the X-axis direction. The side surfaces 4Bc and 4Bd face each other in the Y-axis direction. The side surface 4Bc is located on the negative side of the Y-axis direction, and the side surface 4Bd is located on the positive side of the Y-axis direction.

[0030] The connecting portion 6 is a member that connects the first conductor portion 4A and the second conductor portion 4B. The connecting portion 6 connects one end of the conductor portions 4A and 4B (i.e., the end portions on the positive side in the Z-axis direction) to each other and extends in the Y-axis direction. The connecting portion 6 does not have to be parallel to the Y-axis direction as long as it extends in the Y-axis direction.

[0031] The first terminal 7A is provided at the other end of the first conductor 4A (i.e., the end on the negative side in the Z-axis direction) and extends toward the negative side in the X-axis direction and the positive side in the Y-axis direction. The first terminal 7A is configured by forming a portion of the first conductor 4A near the other end so that it widens toward the positive side in the Y-axis direction and bending the wide portion toward the negative side in the X-axis direction. The second terminal 7B is provided at the other end of the second conductor 4B (i.e., the end on the negative side in the Z-axis direction) and extends toward the negative side in the X-axis direction and the negative side in the Y-axis direction. The second terminal 7B is formed by forming a portion of the second conductor 4B near the other end so that it widens toward the negative side in the Y-axis direction and bending the wide portion toward the negative side in the X-axis direction. The first magnetic block 2A adjacent to the first coil conductor 3A on the negative side in the X-axis direction is placed on the terminals 7A and 7B of the first coil conductor 3A. The terminal portions 7A and 7B are joined to land electrodes 12 of a substrate 11 on which the inductance element 1 is mounted. In this way, the inductance element 1 is mounted on the substrate 11.

[0032] Like the first coil conductor 3A, the second coil conductor 3B includes a first conductor portion 4A, a second conductor portion 4B, a connecting portion 6, a first terminal portion 7A, and a second terminal portion 7B. Unlike the first coil conductor 3A, the second coil conductor 3B has the first terminal portion 7A extending from the other end of the first conductor portion 4A toward the positive side in the X-axis direction and the positive side in the Y-axis direction, and the second terminal portion 7B extending from the other end of the second conductor portion 4B toward the positive side in the X-axis direction and the negative side in the Y-axis direction. A third magnetic block 2C adjacent to the second coil conductor 3B on the positive side in the X-axis direction is placed on the terminal portions 7A and 7B of the second coil conductor 3B. The terminal portions 7A and 7B of the second coil conductor 3B are also bonded to land electrodes 12 of a substrate 11 on which the inductance element 1 is mounted.

[0033] The negative Z-axis direction surfaces of the terminal portions 7A, 7B of the first coil conductor 3A and the terminal portions 7A, 7B of the second coil conductor 3B are both exposed from the element body 90, and the exposed portions are joined to the land electrode 12. Furthermore, a portion of the surface of the terminal portions 7A, 7B of the first coil conductor 3A and the terminal portions 7A, 7B of the second coil conductor 3B adjacent to the negative Z-axis direction surfaces may be exposed from the element body 90, the portion being located on the negative Z-axis direction.

[0034] As an example, the first coil conductor 3A of the inductance element 1 is used as the first inductor L1, and the second coil conductor 3B of the inductance element 1 is used as the second inductor L2.

[0035] The inventors have found that improved characteristics and miniaturization can be achieved by applying the coil conductors 3A and 3B of the inductance element 1 to the DC-DC converter 200. Therefore, the following experiment was carried out to verify this.

[0036] For comparison, in the experiment, an inductance element including a magnetic block made of a crack-free magnetic ribbon (hereinafter referred to as the "crack-free element") as shown in Figure 2 was prepared, as well as an inductance element including a magnetic block made of a magnetic ribbon with numerous cracks (hereinafter referred to as the "crack-containing element"). The crack-free element and the crack-containing element had the same inductance value of 0.2 μH and the same DC bias rated current of 13 A [Isat, -30%]. In this case, the height of the crack-free element (3.5 mm) which achieved the same inductance value and DC bias rated current was smaller than the height of the crack-containing element (3.8 mm).

[0037] For comparison, in addition to the two-phase step-down DC-DC converter 200 with a capacitor voltage division function shown in FIG. 1, a two-phase step-down DC-DC converter 400 without a capacitor voltage division function shown in FIG. 5 was prepared.

[0038] In Comparative Example 1, coil conductors made of non-crack elements were applied to inductors L1 and L2 of DC-DC converter 400 shown in Fig. 5. In Comparative Example 2, coil conductors made of crack-containing elements were applied to inductors L1 and L2 of DC-DC converter 400 shown in Fig. 5. In the Example, coil conductors made of non-crack elements were applied to inductors L1 and L2 of DC-DC converter 200 shown in Fig. 1.

[0039] In Comparative Examples 1 and 2 and the Example, the loss (Pc) [mW] was measured with an input voltage of 12 V and an output voltage of 1.0 V. The inductor loss was measured using a BH analyzer, and the loss under the driving conditions was calculated. As a result, the loss was 406 mW in Comparative Example 1, 320 mW in Comparative Example 2, and 308 mW in the Example.

[0040] As described above, in the DC-DC converter 200 of the power supply circuit 100, the coil conductors 3A and 3B of the inductance element 1 are used as the inductors L1 and L2, thereby improving the characteristics in terms of reducing loss.

[0041] In addition, by including the magnetic block 2 made of the crack-free magnetic ribbon 22 in the inductance element 1, it is possible to achieve miniaturization (particularly a reduction in height) while maintaining element characteristics such as the inductance value and the DC bias rated current, compared to when the inductance element 1 includes a magnetic block made of a magnetic ribbon with countless cracks. Conversely, when the element dimensions are maintained, by including the magnetic block 2 made of the crack-free magnetic ribbon 22 in the inductance element 1, it is possible to improve element characteristics such as the inductance value and the DC bias rated current, compared to when the inductance element 1 includes a magnetic block made of a magnetic ribbon with countless cracks.

[0042] The coil conductors 3A and 3B of the inductance element 1 may be used for both inductors L1 and L2 of the DC-DC converter 200, or one of the coil conductors 3A and 3B may be used for one of the inductors L1 and L2.

[0043] By using the coil conductors 3A and 3B of the inductance element 1 for both inductors L1 and L2 of the DC-DC converter 200, the inductors L1 and L2 can be configured with a single inductance element 1, thereby reducing the size of the DC-DC converter 200. Furthermore, by disposing the magnetic block 2B between the coil conductors 3A and 3B corresponding to the inductors L1 and L2 of the DC-DC converter 200, the coupling between the inductors L1 and L2 is effectively suppressed, thereby suppressing the occurrence of ripples. Furthermore, the first magnetic block 2A and the third magnetic block 2C effectively suppress the coupling between the inductors L1 and L2, improving the inductance value.

[0044] The step-down ratio of the DC-DC converter 200 can be determined as appropriate, but if the step-down ratio is 0.1 or less, harmonic components become large, resulting in a large effect of high-frequency loss. The switching frequency of the DC-DC converter 200 can be determined as appropriate, but if the switching frequency is high, such as 100 kHz or more, the effect of high-frequency loss becomes significant. Since the magnetic ribbons 22 constituting the magnetic block 2 tend to have large high-frequency loss, the DC-DC converter 200 described above can effectively suppress this increase in loss.

[0045] The input voltage of the input power supply 300 may be 10 V or higher. The higher the input voltage, the greater the loss in the inductance element 1. The DC-DC converter 200 described above can effectively suppress the increase in loss.

[0046] As can be understood from the above description, the present specification discloses the following. [Appendix 1] a first input terminal and a second input terminal; a first output terminal and a second output terminal; a first switching element connected to the first input terminal; a first circuit including a first capacitor and a first inductor connected in series in this order between the first switching element and the first output terminal, and a second switching element connected between the first capacitor and the first inductor; a second circuit including a fourth switching element connected in parallel to the first circuit between the first switching element and the first output terminal, a third switching element and a second inductor connected in series in this order, and connected between the third switching element and the second inductor; a second capacitor connected between the first output terminal and the second output terminal; Equipped with at least one of the first inductor and the second inductor is an inductance element including a first coil conductor, a magnetic body arranged in parallel with the first coil conductor, and a magnetic resin that contains the first coil conductor and the magnetic body therein; A DC-DC converter, wherein the magnetic body has a laminated structure in which a plurality of magnetic ribbons are laminated, and each of the magnetic ribbons is not divided into a plurality of small pieces by cracks. [Appendix 2] the inductance element further includes, in addition to the first coil conductor constituting one of the first inductor and the second inductor, a second coil conductor constituting the other of the first inductor and the second inductor; 2. The DC-DC converter according to claim 1, wherein the second coil conductor is contained inside the magnetic resin and is arranged in parallel with the magnetic body. [Appendix 3] 3. The DC-DC converter according to claim 2, wherein the magnetic body of the inductance element is interposed between the first coil conductor and the second coil conductor. [Appendix 4] the magnetic body of the inductance element includes a first magnetic block, a second magnetic block, and a third magnetic block; 4. The DC-DC converter according to claim 2, wherein the first magnetic block is interposed between the first coil conductor and the second coil conductor, the second magnetic block is positioned on the opposite side of the first coil conductor from the first magnetic block side, and the third magnetic block is positioned on the opposite side of the second coil conductor from the first magnetic block side. [Appendix 5] 5. The DC-DC converter according to any one of claims 1 to 4, wherein the step-down ratio is 0.1 or less. [Appendix 6] 6. The DC-DC converter according to any one of claims 1 to 5, wherein the switching frequency is 100 kHz or more. [Appendix 7] A power supply circuit comprising: a DC-DC converter according to any one of appendixes 1 to 6; and an input power supply that inputs a DC voltage of 10 V or more between the first input terminal and the second input terminal of the DC-DC converter. [Explanation of symbols]

[0047] 1...inductance element, 2...magnetic block, 3...coil conductor, 100...power supply circuit, 200, 400...DC-DC converter, 201...first circuit, 202...second circuit, 300...input power supply, A1, A2...input terminal, B1, B2...output terminal, C, C1, C2...capacitor, L1, L2...inductor, SW1, SW2, SW3, SW4...switching elements.

Claims

1. a first input terminal and a second input terminal; a first output terminal and a second output terminal; a first switching element connected to the first input terminal; a first circuit including a first capacitor and a first inductor connected in series in this order between the first switching element and the first output terminal, and a second switching element connected between the first capacitor and the first inductor; a second circuit including a fourth switching element connected in parallel to the first circuit between the first switching element and the first output terminal, a third switching element and a second inductor connected in series in this order, and connected between the third switching element and the second inductor; a second capacitor connected between the first output terminal and the second output terminal; Equipped with at least one of the first inductor and the second inductor is an inductance element including a first coil conductor, a magnetic body arranged in parallel with the first coil conductor, and a magnetic resin that contains the first coil conductor and the magnetic body therein; The DC-DC converter, wherein the magnetic body has a laminated structure in which a plurality of magnetic ribbons are laminated, and each of the magnetic ribbons is not divided into a plurality of small pieces by cracks.

2. the inductance element further includes, in addition to the first coil conductor constituting one of the first inductor and the second inductor, a second coil conductor constituting the other of the first inductor and the second inductor, 2. The DC-DC converter according to claim 1, wherein the second coil conductor is contained inside the magnetic resin and is arranged in parallel with the magnetic body.

3. 3. The DC-DC converter according to claim 2, wherein the magnetic body of the inductance element is interposed between the first coil conductor and the second coil conductor.

4. the magnetic body of the inductance element includes a first magnetic block, a second magnetic block, and a third magnetic block; 3. The DC-DC converter according to claim 2, wherein the first magnetic block is interposed between the first coil conductor and the second coil conductor, the second magnetic block is positioned on the opposite side of the first coil conductor from the first magnetic block side, and the third magnetic block is positioned on the opposite side of the second coil conductor from the first magnetic block side.

5. 2. The DC-DC converter according to claim 1, wherein the step-down ratio is 0.1 or less.

6. 2. The DC-DC converter according to claim 1, wherein the switching frequency is 100 kHz or higher.

7. 7. A power supply circuit comprising: the DC-DC converter according to claim 1; and an input power supply that inputs a DC voltage of 10 V or more between the first input terminal and the second input terminal of the DC-DC converter.

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