JP2009027778A - Bus bar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bus bar which can improve the degree of freedom in arrangement during its management. <P>SOLUTION: The bus bar 10 is equipped with a P bus bar 11 and an N bus bar 12 which supply power from a power source. The N bus bar 12 extends in parallel with the axial direction of the P bus bar 11, and also is arranged to surround the P bus bar 11. An insulator 13 is arranged between the P bus bar 11 and the N bus bar 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bus bar used for a power supply line.

2. Description of the Related Art Conventionally, a power supply line of an electronic device uses a so-called bus bar, which is a plate-like or bar-like conductor such as copper or aluminum, which is not coated with an insulating coating, as a wiring material. Patent Document 1 discloses such a bus bar in which an insulator made of insulating paper or the like is sandwiched between a pair of strip-shaped bus bars extending in parallel.
Japanese Patent Laid-Open No. 2005-12908

  According to the description in Patent Document 1, the bus bar is routed along the smoothing capacitor between the smoothing capacitor placed on the upper part of the switching element power module housed in the inverter case and the peripheral wall of the inverter case. ing. However, the bus bar requires a space for ensuring insulation, and there is a possibility that the degree of freedom in arrangement when the bus bar is routed may be limited.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a bus bar that can improve the degree of freedom in arrangement during handling.

  The bus bar according to the present invention is a bus bar including a first conductor that supplies power from a power source and a second conductor, and the second conductor extends in parallel to the axial direction of the first conductor. And it is arrange | positioned so that a 1st conductor may be enclosed, It is characterized by the above-mentioned.

  With the bus bar according to the present invention, the bus bar can be formed, for example, in a single bar shape by disposing the second conductor so as to surround the first conductor. Therefore, the bus bar can be reduced in size and the handling thereof can be simplified. As a result, it is possible to improve the degree of freedom in arrangement when handling the bus bars.

  It is preferable that irregularities are formed on the outer peripheral surface of the first conductor and the inner peripheral surface of the second conductor so as to mesh with each other.

  In this way, the surface area of the outer peripheral surface of the first conductor and the inner peripheral surface of the second conductor facing each other increases, so that the mutual inductance between the first conductor and the second conductor increases, and the bus bar It is possible to reduce the effective inductance.

  Moreover, it is preferable that an insulator is disposed between the first conductor and the second conductor.

  In this way, it is possible to more reliably prevent a short circuit between the first conductor and the second conductor, and it is possible to further reduce the size of the bus bar.

  According to the present invention, the second conductor is disposed so as to extend parallel to the axial direction of the first conductor and surround the first conductor, thereby allowing freedom in arrangement when the bus bar is routed. The degree can be improved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the figure, the same reference numerals are used for the same or corresponding parts.

  First, the configuration of the bus bar 10 according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of the bus bar 10.

  The bus bar 10 is a wiring material used for supplying power to a power module 20 such as an IGBT (Insulated Gate Bipolar Transistor) which is a power semiconductor device in an electronic device such as an inverter. The bus bar 10 includes a bus bar (hereinafter referred to as “P bus bar”) 11 for connecting the positive electrode of the power source and the power module 20, and a bus bar (hereinafter referred to as “N bus bar”) for connecting the negative electrode of the power source and the power module 20. ) 12.

  The P bus bar 11 is a rod-shaped member having a rectangular cross section, for example. For example, a conductor such as copper or aluminum is used for the P bus bar 11. That is, the P bus bar 11 corresponds to a first conductor described in the claims.

  The N bus bar 12 is, for example, a hollow bar-shaped member whose cross section has a mouth shape. The N bus bar 12 extends parallel to the axial direction of the P bus bar 11 and is disposed so as to surround the P bus bar 11. The N bus bar 12 is also made of a conductor such as copper or aluminum. In other words, the N bus bar 12 corresponds to the second conductor described in the claims.

  The N bus bar 11 and the P bus bar 12 are arranged at a predetermined interval so as not to be short-circuited. An insulator 13 is provided between the outer peripheral surface of the N bus bar 11 and the inner peripheral surface of the P bus bar 12. As the insulator 13, a material that is excellent in heat dissipation (thermal conductivity) and heat resistance and hardly allows current to flow, for example, insulating paper, ceramic, polyphenylene sulfide resin (PPS resin), or the like is used. Note that air may be used as an insulator. The thickness of the insulator 13 is set to a sufficient thickness that does not cause dielectric breakdown in consideration of a potential difference (for example, several hundred to 2000 V) between the P bus bar 11 and the N bus bar 12.

  A hole 13 a and a hole 12 a for taking out a wiring (wire) 21 connecting the P bus bar 11 and the power module 20 are formed on the side surfaces of the insulator 13 and the N bus bar 12. The P bus bar 11 and the electrode of the power module 20 are connected by wire bonding through the holes 13a and 12a. On the other hand, the N bus bar 12 and the electrode of the power module 20 are also connected by wiring (wire) 22.

  Next, the effective inductances of the conventional bus bar and the bus bar 10 according to the present embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram for explaining the effective inductance of a conventional bus bar. FIG. 3 is a diagram for explaining the effective inductance of the bus bar 10.

First, as shown in FIG. 2, the effective inductance of a conventional bus bar in which a pair of conductors 30 and 31 are provided in parallel to each other will be described. The self-inductance Ls (H) of this bus bar is obtained by the following equation (1).
Ls = μ ₀ × N ² × 1 × S (1)
Where μ ₀ is the magnetic permeability (H / m), N is the number of turns, l is the length (m) of the conductors 30 and 31, and S is the cross-sectional area (m ² ) of the conductors 30 and 31.

The mutual inductance M (H) between the conductors is calculated by the following equation (2).
M = μ ₀ × 1 × {(ln (2l / d) −1) / 2π (2)
Where d is the distance (m) between the conductors.

The effective inductance Lop of the conventional bus bar is obtained by substituting the self-inductance Ls obtained from the above equation (1) and the mutual inductance M obtained from the above equation (2) into the following equation (3).
Lop = Ls ₁ + Ls ₂ −2M (3)
However, Ls ₁ is a self-inductance of one conductor 30 constituting the bus bar, and Ls ₂ is a self-inductance of the other conductor 31.

On the other hand, the effective inductance Loi of the bus bar 10 according to the present embodiment substitutes the self-inductance Ls obtained from the above equation (1) and the mutual inductance M obtained from the above equation (2) into the following equation (4). Is required.
Loi = Ls ₁ + Ls ₂ −2M ₁ −2M ₂ −2M ₃ −2M ₄ (4)
However, M ₁ , M ₂ , M ₃ , and M ₄ are mutual inductances for four opposing surfaces of the P bus bar 11 and the N bus bar 12 (see FIG. 3).

  As apparent from the above formulas (3) and (4), according to the bus bar 10 according to the present embodiment, mutual inductance is formed on the four opposing surfaces of the P bus bar 11 and the N bus bar 12, Compared with the conventional bus bar, the mutual inductance between the P bus bar 11 and the N bus bar 12 is increased, so that the effective inductance of the bus bar 10 is reduced. As a result, since the voltage (surge voltage) applied to the power module 20 at the time of switching can be kept low, the durability and reliability of the power module 20 can be improved.

  Here, in order to increase the surface area of the outer peripheral surface of the P bus bar 11 and the inner peripheral surface of the N bus bar 12 facing each other, irregularities are formed on the outer peripheral surface of the P bus bar 11 and the inner peripheral surface of the N bus bar 12 so as to mesh with each other. May be. By doing so, the mutual inductance between the P bus bar 11 and the N bus bar 12 is increased by increasing the surface area of the outer peripheral surface of the opposing P bus bar 11 and the inner peripheral surface of the N bus bar 12. The effective inductance can be further reduced. The surface shape of the outer peripheral surface of the P bus bar 11 and the inner peripheral surface of the N bus bar 12 may be, for example, a sine wave shape or a lightning bolt shape.

  According to the present embodiment, by arranging the N bus bar 12 so as to surround the P bus bar 11, the bus bar 10 can be formed in a single bar shape. Therefore, the bus bar 10 can be reduced in size and the handling thereof can be simplified. As a result, it is possible to improve the degree of freedom in arrangement when handling the bus bar 10.

  Further, by adopting such a structure, the strength of the bus bar 10 can be increased, so that vibration durability and impact resistance can be improved.

  Furthermore, according to the present embodiment, since the wiring is taken out from the wiring taking-out hole 12a formed in the N bus bar 12 arranged so as to surround the outer peripheral surface of the P bus bar 11, the place where the hole 12a is formed By changing, the wiring can be taken out in all directions. Therefore, it is possible to improve the degree of freedom of the wiring method, and it is possible to improve the degree of freedom such as the mounting position and mounting angle of the power module 20.

  According to this embodiment, since the insulator 13 is disposed between the P bus bar 11 and the N bus bar 12, a short circuit between the P bus bar 11 and the N bus bar 12 can be prevented more reliably, and the bus bar can be prevented. 10 can be further downsized.

  Moreover, since the heat dissipation of the P bus bar 11 can be promoted by using a material having a high thermal conductivity as the insulator 13, the bus bar 10 can be reduced in size, and further downsizing of the electronic equipment in which the bus bar 10 is used. Can be realized. In addition, loss of the electronic device can be reduced.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, the cross section of the P bus bar 11 is not limited to a rectangle, and the shape of the P bus bar 11 is not limited to a rod shape. Moreover, the N bus bar 12 should just be arrange | positioned so that the P bus bar 11 may be enclosed, and the cross section is not restricted to a mouth shape.

  In the above embodiment, the N bus bar 12 is arranged so as to surround the P bus bar 11, but the P bus bar 11 and the N bus bar 12 may be interchanged, and the P bus bar 11 may be arranged so as to surround the N bus bar 12.

  Furthermore, by providing heat radiating fins and cooling members on the outer peripheral surface of the N bus bar 12, it is possible to further improve the heat dissipation of the bus bar 10.

It is a figure which shows the structure of the bus-bar which concerns on embodiment. It is a figure for demonstrating the effective inductance of the conventional bus bar. It is a figure for demonstrating the effective inductance of the bus-bar which concerns on embodiment.

Explanation of symbols

  10 ... bus bar, 11 ... P bus bar, 12 ... N bus bar, 13 ... insulator.

Claims (3)

A bus bar comprising a first conductor for supplying power from a power source, and a second conductor,
The bus bar, wherein the second conductor extends parallel to the axial direction of the first conductor and is disposed so as to surround the first conductor.   The bus bar according to claim 1, wherein irregularities are formed on the outer peripheral surface of the first conductor and the inner peripheral surface of the second conductor so as to mesh with each other.   The bus bar according to claim 1, wherein an insulator is disposed between the first conductor and the second conductor.

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