WO2025206776A1 - Inductor - Google Patents

Abstract

The inductor comprises: a first core comprising a first base, a first outer leg extending from the edge of one surface of the first base in a first direction, and a first central leg extending from the center of the one surface of the first base in the first direction; a second core comprising a second base, a second outer leg extending from the edge of one surface of the second base in a direction opposite to the first direction, and a second central leg extending from the center of the one surface of the second base in the direction opposite to the first direction; a third core comprising a third base, a third outer leg extending from then edge of one surface of the third base in the direction opposite to the first direction, and a third central leg extending from the center of the one surface of the third base in the direction opposite to the first direction; a first coil wound around the first central leg and the second central leg; and a second coil wound around the third central leg, wherein the first central leg and the second central leg extend in opposite directions, and the third central leg extends toward the other surface of the second base.

Description

Inductor

The present invention relates to an inductor and an inductor module including the same.

Solar power generation is becoming widely adopted as an eco-friendly energy source, replacing conventional chemical and nuclear power generation. Solar power generation can be either standalone, with a battery connected to a converter, or grid-connected. Standalone systems typically consist of solar cells, storage batteries, and power conversion equipment, while grid-connected systems are connected to commercial power sources, enabling the exchange of power with load grid lines.

The power generated by solar panels cannot be used directly in homes or buildings. Therefore, it must be converted into usable power using a power conversion device such as an inverter. Inverters utilize inductors to boost the voltage during power conversion. The size of these inductors is a key factor in overall circuit density, and technology that can reduce their size is essential.

The technical problem to be solved by the present invention is to provide an inductor having a high power density and an inductor module including the same.

In order to solve the above technical problem, an inductor according to an embodiment of the present invention includes a first core including a first base, a first outer leg extending in a first direction from an edge of one side of the first base, and a first middle leg extending in the first direction from a center of the one side of the first base; a second core including a second base, a second outer leg extending in a direction opposite to the first direction from an edge of one side of the second base, and a second middle leg extending in a direction opposite to the first direction from a center of the one side of the second base; a third core including a third base, a third outer leg extending in a direction opposite to the first direction from an edge of one side of the third base, and a third middle leg extending in a direction opposite to the first direction from a center of the one side of the third base; a first coil wound around the first middle leg and the second middle leg; And a second coil wound around the third intermediate leg, wherein the first intermediate leg and the second intermediate leg extend in opposite directions to each other, and the third intermediate leg extends in the direction of the other surface of the second base.

Additionally, the first coil may be placed in a space surrounded by one surface of the first base, the inner surface of the first outer leg, the one surface of the second base, and the inner surface of the second outer leg.

Additionally, the second coil may be placed in a space surrounded by the one surface of the third base, the inner surface of the third outer leg, and the other surface of the second base.

Additionally, the length of the second extremity in the first direction may be longer than the length of the third extremity in the first direction.

Additionally, the length of the first extremity in the first direction may be the same as the length of the second extremity in the first direction.

Additionally, the thickness of the second intermediate leg may be the same as the thickness of the third intermediate leg.

In addition, the first extremity is a 1-1 extremity positioned on one side of the first base; and

It may include 1-2 outer legs arranged on the other side of the first base.

Additionally, the first base, the first outer leg, and the first middle leg may each be formed as a block.

Additionally, the first coil may be an inverter side inductor coil, and the second coil may be a grid side inductor coil.

Additionally, the first coil and the second coil can be electrically connected.

In order to solve the above technical problem, an inductor module according to an embodiment of the present invention includes a housing forming an internal space; and one or more inductors disposed in the internal space, wherein the inductor includes a first core including a first base, a first outer leg extending in a first direction from an edge of one side of the first base, and a first middle leg extending in the first direction from a center of the one side of the first base; a second core including a second base, a second outer leg extending in a direction opposite to the first direction from an edge of one side of the second base, and a second middle leg extending in a direction opposite to the first direction from a center of the one side of the second base; a third core including a third base, a third outer leg extending in a direction opposite to the first direction from an edge of one side of the third base, and a third middle leg extending in a direction opposite to the first direction from a center of the one side of the third base; a first coil wound around the first middle leg and the second middle leg; And a second coil wound around the third intermediate leg, wherein the first intermediate leg and the second intermediate leg extend in opposite directions to each other, and the third intermediate leg extends in the direction of the other surface of the second base.

In addition, the inductor includes a first inductor and a second inductor, and the first coil of the first inductor and the second coil of the first inductor are connected in series, the first coil of the second inductor and the second coil of the second inductor are connected in series, the first coil of the first inductor and the first coil of the second inductor are connected in parallel, and the second coil of the first inductor and the second coil of the second inductor can be connected in parallel.

Additionally, the first coil may be placed in a space surrounded by one surface of the first base, the inner surface of the first outer leg, the one surface of the second base, and the inner surface of the second outer leg.

Additionally, the second coil may be placed in a space surrounded by the one surface of the third base, the inner surface of the third outer leg, and the other surface of the second base.

Additionally, the length of the second extremity in the first direction may be longer than the length of the third extremity in the first direction.

Additionally, the length of the first extremity in the first direction may be the same as the length of the second extremity in the first direction.

Additionally, the thickness of the second intermediate leg may be the same as the thickness of the third intermediate leg.

In addition, the first extremity is a 1-1 extremity positioned on one side of the first base; and

It may include 1-2 outer legs arranged on the other side of the first base.

Additionally, the first base, the first outer leg, and the first middle leg may each be formed as a block.

Additionally, the first coil may be an inverter side inductor coil, and the second coil may be a grid side inductor coil.

According to embodiments of the present invention, inductance can be increased within the same size by utilizing the coupling of the core. Furthermore, the quality of current flowing into the system can be maximized at the same power density, and the efficiency and power density of the inverter's power conversion circuit can be increased.

FIG. 1 illustrates an inductor according to one embodiment of the present invention.

Figures 2 to 4 are drawings for explaining an inductor according to an embodiment of the present invention.

FIG. 5 illustrates an inductor module according to one embodiment of the present invention.

Fig. 6 illustrates an inductor module according to an embodiment of the present invention.

Fig. 7 illustrates an inductor module according to a comparative example of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

However, the technical idea of the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of the present invention, one or more of the components between the embodiments can be selectively combined or substituted for use.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention may be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, may be interpreted in consideration of the contextual meaning of the relevant technology.

Additionally, the terms used in the embodiments of the present invention are intended to describe the embodiments and are not intended to limit the present invention.

In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as “A and/or at least one (or more) of B, C”, it may include one or more of all combinations that can be combined with A, B, C.

Additionally, in describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, it may include not only cases where the component is 'connected', 'coupled', or 'connected' directly to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.

Additionally, when described as being formed or arranged "above" or "below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when expressed as "above" or "below," the meaning may include not only the upward direction but also the downward direction based on one component.

FIG. 1 illustrates an inductor according to one embodiment of the present invention.

FIGS. 2 to 4 are drawings for explaining an inductor according to an embodiment of the present invention.

An inductor (100) according to an embodiment of the present invention is composed of a first core (110), a second core (120), a third core (130), a first coil (141), and a second coil (142).

An inductor according to an embodiment of the present invention may be configured as a separate module as an inductor module and may be applied to an inverter module. An inverter module according to an embodiment of the present invention to which an inductor according to an embodiment of the present invention is applied may be a PV inverter module. A PV inverter module is a device that receives power from a PV panel or a PV converter and converts it into power that can be used in a home or building. It receives DC power such as a PV converter, converts it into AC power, and outputs it. At this time, the DC power is transmitted to an inverter driving unit through a wire connection, and the inverter driving unit converts the power, and then transmits the converted power to a load again through the wire connection. The inverter driving unit may include a power conversion element and a switching element or an MCU for controlling the power conversion element. The power conversion element may include a passive element such as an inductor or a capacitor, and may include a switching element implemented as a FET or a diode, and may include an MCU for controlling the switching element. In addition, various elements for converting power may be included, or elements for implementing functions other than power conversion may be included.

The first core (110) includes a first base (111), a first outer leg (112), and a first middle leg (113).

The first base (111) may have a plate shape. A first outer leg (112) and a first intermediate leg (113) may be extended and arranged from the first base (111). The first outer leg (112) extends in a first direction from an edge of one side of the first base (111). Here, the first direction may be an upper direction of the first base (111). The first outer leg (112) may include a first-first outer leg and a first-second outer leg extending from one side, an opposite side of the one side, and both sides of the first base (111). The first intermediate leg (113) extends in the first direction from the center of one side of the first base (111). The cross-sectional area of the first intermediate leg may be formed in a circular or rectangular shape. The first core (110) may include a first intermediate leg (113) in the center from the first base (111), a first-first outer leg and a first-second outer leg arranged on both sides of the first intermediate leg (113).

The first base (111), the first outer leg (112), and the first middle leg (113) can each be formed as blocks. The blocks can be formed using magnetic powder, and the blocks can be assembled to form the first core (110). At this time, each block can be a ferromagnetic block. Or, it can be a soft magnetic block. It goes without saying that the first base (111), the first outer leg (112), and the first middle leg (113) can be formed as a single unit.

The second core (120) includes a second base (121), a second outer leg (122), and a second middle leg (123).

The second base (121) may have a plate shape. A second outer leg (122) and a second middle leg (123) may be extended and arranged from the second base (121). The second outer leg (122) extends from an edge of one side of the second base (121) in a direction opposite to a first direction. Here, the direction opposite to the first direction may be a direction facing the first core (110). The second outer leg (122) may include two outer legs extending from one side of the second base (121) and the opposite side of the one side, that is, from both sides. The second middle leg (123) extends from the center of one side of the second base (121) in a direction opposite to the first direction. The cross-sectional area of the second middle leg may be formed in a circular or rectangular shape. The second core (120) may include a second intermediate leg (123) in the center from the second base (121) and two second outer legs (122) arranged on both sides of the second intermediate leg (123).

The first core (110) and the second core (120) can be in contact with each other to form one core. The first outer leg (112) and the first middle leg (113) of the first core (110) can be in contact with and combined with the second outer leg (122) and the second middle leg (123) of the second core (120), respectively. Through this, a space surrounded by the first base (111), the first outer leg (112), the second base (121), and the second middle leg (122) can be formed. The first middle leg (113) and the second middle leg (123) can be positioned at the center of the space.

The second base (121), the second outer leg (122), and the second middle leg (123) can each be formed as blocks. The blocks can be formed using magnetic powder, and the blocks can be assembled to form the second core (120). At this time, each block can be a ferromagnetic block. Or, it can be a soft magnetic block. It goes without saying that the second base (121), the second outer leg (122), and the second middle leg (123) can be formed as a single unit.

The third core (130) includes a third base (131), a third outer leg (132), and a third middle leg (133).

The third base (131) may have a plate shape. A third outer leg (132) and a third intermediate leg (133) may be extended and arranged from the third base (131). The third outer leg (132) extends from an edge of one side of the third base (131) in a direction opposite to a first direction. Here, the direction opposite to the first direction may be a direction facing the second core (120). The third outer leg (132) may include two outer legs extending from one side of the third base (131) and the opposite side of the one side, that is, from both sides. The third intermediate leg (133) extends from the center of one side of the second base (121) in a direction opposite to the first direction. The cross-sectional area of the third intermediate leg may be formed in a circular or rectangular shape. The third core (130) may include a third intermediate leg (133) in the center from the third base (131) and two third outer legs (132) arranged on either side of the third intermediate leg (133).

The third core (130) can be in contact with and coupled to the other surface of the second base (121) of the second core (120), so that the first core (110), the second core (120), and the third core (130) can form one core. The third outer leg (132) and the third middle leg (133) of the third core (130) can be in contact with and coupled to the other surface of the second base (121). Through this, a space surrounded by the second base (121), the third base (131), and the third outer leg (132) can be formed. The third middle leg (133) can be positioned at the center of the space.

The third base (131), the third outer leg (132), and the third middle leg (133) can each be formed as blocks. The blocks can be formed using magnetic powder, and the blocks can be assembled to form the third core (130). At this time, each block can be a ferromagnetic block. Or, it can be a soft magnetic block. It goes without saying that the third base (131), the third outer leg (132), and the third middle leg (133) can be formed as a single unit.

The first coil (141) is wound and arranged around the first intermediate leg (113) and the second intermediate leg (123).

The first coil (141) may be wound around the first intermediate leg (113) and the second intermediate leg (123). The first coil (141) may be a metal wire, for example, a copper wire. It may be formed in a shape that wraps around the first intermediate leg (113) and the second intermediate leg (123), thereby forming an inductor. The first coil (141) may be placed in a space formed by the first core (110) and the second core (120). The first coil (141) may be placed in a space surrounded by one surface of the first base (111), the inner surface of the first outer leg (112), one surface of the second base (121), and the inner surface of the second outer leg (122), and may be formed in a shape that wraps around the first intermediate leg (113) and the second intermediate leg (123) that are positioned at the center of the space and face each other and make contact.

The second coil (142) is wound around the third intermediate leg (133). The second coil (142) may be a metal wire, for example, a copper wire. It may be formed in a shape that wraps around the third intermediate leg (133), thereby forming an inductor. The second coil (142) may be placed in a space formed by the second base (121) of the second core (120) and the third core (130). The first coil (141) may be placed in a space surrounded by the other surface of the second base (121), one surface of the third base (131), and the inner surface of the third outer leg (132), and may be formed in a shape that wraps around the third intermediate leg (133) located at the center of the space.

The first coil (141) and the second coil (142) can be respectively placed on two spaces of one inductor core composed of the first core (110), the second core (120), and the third core (130). At this time, the first intermediate leg (113), the second intermediate leg (123), and the third intermediate leg (133) are connected in the form of one intermediate leg, so that the first coil (141) and the second coil (142) are magnetically coupled, thereby increasing the power density.

The first coil (141) and the second coil (142) may be spaced apart from each other by the second base (121). The first coil (141) and the second coil (142) may each form an inductor. The first coil (141) may be an inverter-side inductor coil, and the second coil (142) may be a grid-side inductor coil. As shown in Fig. 2, an LCL filter may be included between the inverter (210) and the grid (220). The LCL filter is a filter composed of an inverter-side inductor (151), a capacitor (170), and a grid-side inductor (152), and is a filter that can effectively attenuate current ripple and satisfy the current quality required by the grid (220). The first coil (141) may form an inverter-side inductor (151), and the second coil (142) may form a grid-side inductor (152).

The first coil (141) and the second coil (142) are arranged spaced apart from each other, but one of the two connecting lines drawn from each coil can be electrically connected to each other. At this time, the first coil (141) and the second coil (142) can be connected in series. The inverter side inductor (151) and the grid side inductor (152) can be connected in series, and the first coil (141) and the second coil (142) can also be connected in series.

The length of the second outer leg (122) in the first direction may be formed longer than the length of the third outer leg (132) in the first direction. The length of the first outer leg (112) in the first direction may be the same as the length of the second outer leg (122) in the first direction. The first core (110) and the second core (120) may be arranged to face each other in the arrangement direction, but their shapes may correspond to each other. As shown in Fig. 3, the length (F1) of the first outer leg (112) in the first direction may be the same as the length (F2) of the second outer leg (122) in the first direction, and the length (F2) of the second outer leg (122) in the first direction may be formed longer than the length (F3) of the third outer leg (132) in the first direction. The inductance capacity of the inverter side inductor (151) must be greater than the inductance capacity of the grid side inductor (152), and accordingly, the number of times the first coil (141) winds the first intermediate leg (113) and the second intermediate leg (123) must be greater than the number of times the second coil (142) winds the third intermediate leg (133), and the length (F2) of the second outer leg (122) in the first direction can be formed to be longer than the length (F3) of the third outer leg (132) in the first direction.

The thickness of the second intermediate leg (123) may be the same as the thickness of the third intermediate leg (133). The thickness (D2) of the third intermediate leg (133) around which the second coil (142) is wound may be formed to be the same as the thickness (D1) of the second intermediate leg (123) around which the first coil (141) is wound. Through this, in order to implement the inductance of the grid-side inductor (152), the number of times the second coil (142) is wound around the third intermediate leg (133) may be reduced.

As described above, the first core (110), the second core (120), and the third core (130) constitute one core, but two spaces are formed in which the first coil (141) and the second coil (142) are placed, thereby forming an integrated inductor in which two inductors are integrated.

Through this, it is possible to increase the inductance at the same size by utilizing the coupling of the core, maximize the quality of the current flowing into the system at the same power density, and increase the efficiency and power density of the power conversion circuit of the inverter.

Fig. 5 illustrates an inductor module according to one embodiment of the present invention. A detailed description of each component of the inductor of the inductor module of Fig. 5 corresponds to the detailed description of the inductor of Figs. 1 to 4, and thus, any redundant description will be kept brief.

An inductor module according to an embodiment of the present invention includes a housing (180) and an inductor (100).

The housing (180) forms an internal space (181) that accommodates the inductor (100). The housing (180) may include a base and a side plate extending from the base. The inductor (100) may be accommodated within the internal space (181) formed by the base and the side plate. A plurality of heat dissipation fins (183) are formed on the outer surface (182) of the side plate to dissipate heat generated from the inductor (100) to the outside. The inductor (100) may be placed in the internal space of the housing (180) and molded using a molding liquid. The molding may increase the conductivity of heat.

The inductor (100) is placed inside the housing (110). The inductor (120) may include one or more inductors, and may include multiple inductors depending on the characteristics of the boost circuit of the inverter module to which the inductor module is applied. The inductor (120) may include an inductor connected to the input terminals of multiple solar modules, and may include an inverter-side inductor (151) or a grid-side inductor (152) of the power conversion module. In addition, various inductors may be included. The housing (180) includes respective receiving portions corresponding to the multiple inductors, and each inductor or inductors of the same type may be placed inside the housing (110) separately from other inductors.

The inductor (100) includes a first core (110), a second core (120), a third core (130), a first coil (141), and a second coil (142). The first core (110) includes a first base (111), a first outer leg (112) extending in a first direction from an edge of one surface of the first base (111), and a first middle leg (113) extending in the first direction from the center of one surface of the first base (111). The first base (111), the first outer leg (112), and the first middle leg (113) may each be formed as a block.

The second core (120) includes a second base (121), a second outer leg (122) extending in a direction opposite to the first direction from an edge of one side of the second base (121), and a second intermediate leg (123) extending in a direction opposite to the first direction from a center of one side of the second base (121), and the third core (130) includes a third base (131), a third outer leg (132) extending in a direction opposite to the first direction from an edge of one side of the third base (131), and a third intermediate leg (133) extending in a direction opposite to the first direction from a center of one side of the third base (131). The first intermediate leg (113) and the second intermediate leg (123) extend in opposite directions, and the third intermediate leg (133) may extend in the direction of the other side of the second base (121).

The first coil (141) may be formed by being wound around the first intermediate leg (113) and the second intermediate leg (123), and the second coil (142) may be formed by being wound around the third intermediate leg (133). The first coil (141) may be arranged in a space surrounded by one surface of the first base (111), the inner surface of the first outer leg (112), one surface of the second base (121), and the inner surface of the second outer leg (122), and the second coil (142) may be arranged in a space surrounded by one surface of the third base (131), the inner surface of the third outer leg (132), and the other surface of the second base (121). The first coil (141) may be an inverter-side inductor coil, and the second coil (142) may be a grid-side inductor coil.

The length of the second outer leg (122) in the first direction may be longer than the length of the third outer leg (132) in the first direction, the length of the first outer leg (112) in the first direction may be equal to the length of the second outer leg (122) in the first direction, and the thickness of the second intermediate leg (123) may be equal to the thickness of the third intermediate leg (133).

Fig. 6 illustrates an inductor module according to an embodiment of the present invention.

The inductor (100) may include a first inductor (610) and a second inductor (620). The first inductor (610) and the second inductor (620) may include corresponding configurations. The first inductor (610) and the second inductor (620) may each include a first core (110), a second core (120), a third core (130), a first coil (141), and a second coil (142).

The first coil (141) of the first inductor (610) and the second coil (142) of the first inductor (610) are connected in series, the first coil (141) of the second inductor (620) and the second coil (142) of the second inductor (620) are connected in series, the first coil (141) of the first inductor (610) and the first coil of the second inductor (620) are connected in parallel, and the second coil (142) of the first inductor (610) and the second coil (142) of the second inductor (620) can be connected in parallel.

As shown in Fig. 2, the LCL filter may include two inverter-side inductors (151, 161) and two grid-side inductors (152, 162). Here, the first coil (141) of the first inductor (610) and the first coil (141) of the second inductor (620) may constitute two inverter-side inductors (151, 161), respectively, and the second coil (142) of the first inductor (610) and the second coil (142) of the second inductor (620) may constitute two grid-side inductors (152, 162), respectively.

Fig. 7 illustrates an inductor module according to a comparative example of the present invention. Fig. 7 illustrates an inductor module including four inductors, which may include two inductors (11, 12) forming an inverter-side inductor and two inductors (21, 22) forming a grid-side inductor within a housing (180). At this time, the size of each inductor may be formed to the following size according to the standard of Fig. 4.

The sizes (unit: mm) of each of the two inductors (11, 12) that constitute the inverter side inductor are as follows.

[Table 1]

The sizes (unit: mm) of each of the two inductors (21, 22) that constitute the grid side inductor are as follows.

[Table 2]

The sum of the core volumes of four inductors having that size can be 0.74 L.

In contrast, the core of the inductor according to the embodiment of the present invention is 70.6 x 89.6 mm, which is the same size as the inverter side inductor of Fig. 7. The sum of the core volumes of the two inductors is 0.64 L, which is a size reduction of about 14% compared to the comparative example of Fig. 7 that configures four separate inductors. That is, by forming two inductor cores with the same size inductor cores, it is possible to increase the inductance at the same size using the coupling of the cores, maximize the quality of the current flowing into the system at the same power density, and increase the efficiency and power density of the power conversion circuit of the inverter.

As described above, the present invention has been described with specific details such as specific components and limited examples and drawings, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those with ordinary knowledge in the field to which the present invention pertains can make various modifications and variations from this description.

Therefore, the idea of the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the following claims as well as the claims are considered to fall within the scope of the idea of the present invention.

Claims (10)

A first core including a first base, a first outer leg extending in a first direction from an edge of one side of the first base, and a first middle leg extending in the first direction from a center of the one side of the first base; A second core including a second base, a second outer leg extending in a direction opposite to the first direction from an edge of one side of the second base, and a second middle leg extending in a direction opposite to the first direction from the center of the one side of the second base; A third core including a third base, a third outer leg extending in a direction opposite to the first direction from an edge of one side of the third base, and a third middle leg extending in a direction opposite to the first direction from the center of the one side of the third base; A first coil wound around the first intermediate leg and the second intermediate leg; and including a second coil wound around the third intermediate leg, The first metatarsal and the second metatarsal extend in opposite directions, The above third intermediate leg is an inductor extending in the direction of the second base. In the first paragraph, The above first coil, An inductor arranged in a space surrounded by the first surface of the first base, the inner surface of the first outer group, the first surface of the second base, and the inner surface of the second outer group. In the first paragraph, The above second coil, An inductor arranged in a space surrounded by the first surface of the third base, the inner surface of the third outer base, and the other surface of the second base. In the first paragraph, The length of the second extremity in the first direction is An inductor longer than the length of the third extrinsic in the first direction. In the first paragraph, The length of the first extremity in the first direction is An inductor having a length equal to that of the second extremity in the first direction. In the first paragraph, The thickness of the second metatarsal is An inductor having the same thickness as the third intermediate layer. In the first paragraph, The above first exogamous tribe is, A first-first outer leg arranged on one side of the first base; and An inductor including first and second outer groups arranged on the other side of the first base. In the first paragraph, An inductor in which the first base, the first outer group, and the first middle group are each formed as blocks. In the first paragraph, The above first coil is an inverter side inductor coil, The above second coil is an inductor which is a grid-side inductor coil. In the first paragraph, The above first coil and the above second coil are an inductor that are electrically connected.