KR20210057637A - Laminated bus bar, designing method of laminated bus bar, and battery module - Google Patents

Abstract

An objective is to provide a laminated bus bar capable of carrying a direct current as well as an alternating current, and having an FFC and flexibility in which heat emission is low and heat radiation efficiency is high. Also, a battery module employing the laminated bus bar is provided. Also, a method of designing the laminated bus bar having low heat emission and carrying a high current is provided. To achieve the objective, the laminated bus bar is a laminated bus bar in which a plurality of flexible flat cables (FFC) are laminated. Each of the flexible flat cables includes two organic resin films, a plurality of metal flat plates between the two organic resin films, and an adhesive bonding the two organic resin films to the plurality of metal flat plates, wherein the adhesive is installed between the adjacent metal flat plates, and a heat radiation factor of each of the two organic resin films and the adhesive is higher than a heat radiation factor of the metal flat plates.

Description

Laminated bus bar, designing method of laminated bus bar, and battery module}

The present invention relates to a laminated busbar in which a so-called FFC (Flexible Flat Cable) having a metal plate formed on an organic resin film is laminated, and a design method thereof.

Busbar is a component for connecting power to each part. In recent years, with the spread of next-generation vehicles such as hybrid vehicles or electric vehicles, demand for automotive electronic devices and electric devices that respond to high voltage and high current is expected to increase. The busbar is an important part as one of such next-generation automobile parts.

The busbar functions as an electronic component such as a motor, an inverter, or a generator, an electronic device, or a so-called wiring component that electrically connects the electronic device. In general, a large current flows through a bus bar of a vehicle, but electronic components, electronic devices, electronic or electric devices may cause not only direct current (DC) but also alternating current (AC) to flow through the bus bar.

When a high current flows through the bus bar, it is necessary to increase the cross-sectional area of the metal bar in order to reduce the resistance of the metal bar of the bus bar. However, in the case of an alternating current, even if the cross-sectional area of the metal bar of the bus bar is increased, the current does not flow only near the surface of the metal bar due to the skin effect. When considering the skin effect, the surface depth δ of the metal bar through which the current flows is expressed as (Equation 1).

[Wed 1]

Here, ρ is the electrical resistance of the metal bar, f is the frequency, and μ is the absolute transmittance of the metal bar. In (Equation 1), the higher the frequency of the alternating current, the less current flows only near the surface of the metal bar. Therefore, as for an electronic component, an electronic device, an electronic device, or another electric device that requires an alternating current, a bus bar made of a flat metal bar is used (see, for example, Patent Document 1).

[Patent Document 1] Japanese Unexamined Patent Publication No. 2006-310079

However, when the metal bar of the busbar is made into a flat plate shape and the cross-sectional area is reduced, the resistance of the metal bar increases. Therefore, it is difficult to use a bus bar having a flat metal bar when passing a direct current. In addition, even when an alternating current is passed, the resistance of the direct current component increases, so the effective resistance of the metal bar of the busbar must eventually increase. Such an increase in the resistance of the metal bar of the busbar is not preferable because not only the current flowing through the busbar is reduced, but also the temperature of the busbar increases due to heat generation.

In view of the above problems, an object of the present invention is to provide an FFC having low heat generation and high heat dissipation efficiency and a flexible multilayer bus bar capable of passing not only a direct current but also an alternating current. In addition, it is an object to provide a battery module to which a laminated busbar is applied. In addition, it is an object to provide a method of designing a multilayer bus bar that has low heat generation and can pass a large current.

A laminated busbar according to an embodiment of the present invention is a laminated busbar in which a plurality of flexible flat cables (FFCs) are laminated, and each of the plurality of flexible flat cables (FFCs) includes two organic resin films and two organic resins. Including a plurality of metal plates between the films, and an adhesive bonding with the two organic resin films and the plurality of metal plates, the adhesive is installed between the adjacent metal plates, and the thermal emissivity of each of the two organic resin films and the adhesive is a metal plate Higher than the thermal emissivity of.

A laminated busbar according to an embodiment of the present invention is a laminated busbar in which a plurality of flexible flat cables (FFCs) are laminated, and each of the plurality of flexible flat cables (FFC) has two organic resin films and two organic resins. Two adjacent flexible flat cables out of a plurality of flexible flat cables (FFCs) in which an adhesive is installed between adjacent metal plates, including a plurality of metal plates between the membranes, and an adhesive that bonds to the two organic resin layers and a plurality of metal plates. In (FFC), the number of a plurality of metal flat plates contained in each is different, and the thermal emissivity of each of the two organic resin films and the adhesive is higher than that of the metal flat plate.

The thermal emissivity of the two organic resin films may be 0.8 or more. Also, the two organic resin film materials may be polycyclohexane dimethylene terephthalate (PCT).

The material of the adhesive may be polyester.

The metal plate is a square, and the length of the long side of the square may be 5 times or more of the length of the short side of the square.

The physical quantity of the metal plate is less than a specific value obtained by using the physical quantity of the metal bar, which is obtained under predetermined conditions of the rigid busbar using the material of the metal plate as the metal bar, and the physical quantity of the metal plate corresponding to the physical quantity of the metal bar. As a parameter, the structure of the metal plate can be determined.

In the battery module according to an embodiment of the present invention, a first battery cell and a second battery cell, and an electrode of the first battery and an electrode of the second battery cell are electrically connected, and a plurality of flexible flat cables (FFC) are provided. Including a stacked laminated busbar, each of the plurality of flexible flat cables (FFC) includes two organic resin films, a plurality of metal flat plates between the two organic resin films, two organic resin films, and the plurality of metals. An adhesive bonded to a flat plate is included, wherein an adhesive is formed between the adjacent metal flat plates, and the thermal emissivity of each of the two organic resin films and the adhesive is higher than that of the metal flat plate.

The first battery cell is included in the first battery unit, and the second battery cell is included in a second battery unit different from the first battery unit.

The busbar design method according to an embodiment of the present invention comprises two organic resin films, a plurality of metal plates between the two organic resin films, and an adhesive that bonds the two organic resin films and the plurality of metal plates. It is a method of designing a laminated bus bar in which a plurality of flexible flat cables (FFCs) are stacked, and the physical quantity of the metal bar is obtained under predetermined conditions of a rigid bus bar using a material of a metal flat plate as a metal bar, and the above Under a predetermined condition, the physical quantity of the metal plate is obtained, a specific value is calculated using the physical quantity of the metal bar and the physical quantity of the metal plate, and the metal plate structure is determined by using the physical quantity of the metal plate as a parameter to be less than a specific value. .

The physical quantity of the metal bar is the cross-sectional area A _{1 of the metal bar, and the physical quantity of the metal plate is the total cross-sectional area A 2} of the plurality of metal plates included in the stacked plurality of flexible flat cables (FFC), and the total cross-sectional area A of the plurality of metal plates ₂ can satisfy the following equation.

[Wed 2]

The cross-sectional area A ₁ of the metal bar may be 90 mm 2.

1A is a perspective view of a laminated busbar according to an embodiment of the present invention.
1B is a schematic side view of a stacked busbar according to an embodiment of the present invention.
Fig. 2A is a cross-sectional view in a long side direction of a flexible flat cable of a laminated busbar according to an embodiment of the present invention.
Fig. 2B is a cross-sectional view in the short side direction of a flexible flat cable of a laminated busbar according to an embodiment of the present invention.
Fig. 3A is a side view showing a simulation configuration of a stacked busbar according to an embodiment of the present invention.
3B is a cross-sectional view showing a simulation configuration of a stacked busbar according to an embodiment of the present invention.
Fig. 4A is a side view showing a simulation configuration of a bus bar not containing an organic resin film and an adhesive as a comparative example.
Fig. 4B is a cross-sectional view showing a simulation configuration of a bus bar not containing an organic resin film and an adhesive as a comparative example.
^{[Fig. 5] is a graph of each of the squared current I 2} (ｘ) and the reserve resistance R(x) with respect to the parameter x indicated in the power loss Ploss.
6 is a schematic side view of a stacked busbar according to an embodiment of the present invention.
7 is a schematic perspective view of a battery module 20 according to an embodiment of the present invention.
Hereinafter, each embodiment of the present invention will be described with reference to the drawings. In addition, the embodiment is only an example, and it is obviously included in the scope of the present invention that those skilled in the art can change appropriately and easily conceive while maintaining the knowledge of the invention. In addition, in order to clarify the description, the drawings may schematically indicate the width, thickness, shape, etc. of each part compared to the actual shape. However, the illustrated shape is only an example and does not limit the interpretation of the present invention.
In the present specification and drawings, the same reference numerals are used when a plurality of identical or similar configurations are generally indicated. In addition, hyphens and natural numbers may be used to distinguish and indicate a plurality of parts in one composition.

<First embodiment>

First, the structure of the stacked busbar and the theoretical mechanism related to the stacked busbar according to an embodiment of the present invention will be described, and then, a design method of the stacked busbar will be described.

[One. Structure of stacked busbar]

A structure of a stacked busbar 10 according to an embodiment of the present invention will be described with reference to Figs. 1A and 1B.

1A is a perspective view of a stacked busbar 10 according to an embodiment of the present invention. The laminated busbar 10 has a structure in which a plurality of flexible flat cables (FFC) 100 are laminated. Hereinafter, the long side direction of the FFC100 will be described as the X direction, the short side direction of the FFC100 will be the Y direction, and the stacking direction of the FFC100 will be described as the Z direction.

The stacked busbar 10 includes a body portion 11 and terminal portions 12 provided at both edges of the body 11. The body part 11 is an insulator part, and the terminal part 12 is a conductor part. That is, the multilayer busbar 10 is electrically connected to other electronic components, electronic devices, electronic devices, or electric devices using the terminal portion 12 by using the terminal portion 12. Although not shown, the main body 11 may be provided with a protective cover on the outside of the stacked FFC110 in order to protect the FFC100. Also, although not shown, the terminal 12 may be provided with a connector for connecting with other electronic components, electronic devices, and electronic or electric devices.

1B is a schematic side view of a stacked busbar 10. As shown in Fig. 1B, the stacked bus bar 10 is a plurality of FFC100-1, 100-2, ... in the Z direction. , 100-n are being stacked. Here, a case where a plurality of FFCs is not particularly distinguished will be described as FFC100 for convenience. That is, in the stacked busbar 10 of Fig. 1B, n layers of FFC100 are stacked in the Z direction.

1B shows adjacent FFC100s of the stacked busbar 10 spaced apart from each other for convenience of explanation, but the adjacent FFC100s do not need to be spaced apart from each other. That is, some of the adjacent FFC100s may be in contact with each other. Further, adjacent FFCs may be bonded with an adhesive.

Subsequently, the structure of the FFC100 constituting the stacked busbar 10 will be described with reference to Figs. 2A and 2B.

2A is a cross-sectional view of the FFC100 in the long side direction (X direction), and FIG. 2B is a cross-sectional view of the FFC100 in the short side direction (Y direction). 2A and 2B, each of the plurality of FFC100s includes two organic resin films 110-1 and 110-2, a plurality of metal plates 120-1, 120-2, ... , 120-m, and adhesive 130. Here, a case where a plurality of metal plates is not particularly distinguished will be described as a metal plate 120 for convenience. That is, in the FFC100 of FIGS. 2A and 2B, m metal plates 120 are fixed between the two organic resin films 110-1 and 110-2 with an adhesive 130. Further, in a region sandwiched between the two organic resin films 110-1 and 110-2, two adjacent metal plates 120 are not adjacent to each other, and an adhesive 130 is present between the two adjacent metal plates 120.

On the other hand, the metal plate 120 in the X direction includes metal cladding portions 121 protruding from the two organic resin films 110-1 and 110-2. That is, in the FFC100, the metal clad portion 121 of the metal plate 120 is exposed from both sides of the X-direction. The metal cladding portions 121 of the plurality of metal plates 120 may contact each other. In addition, the metal cladding portions 121 of the plurality of metal plates 120 may contact each other in the n-layer FFC100 as well as the one-layer FFC100. The metal clad portions 121 of the plurality of metal plates 120 may be directly contacted, may be bonded to each other, or may be contacted through a conductive adhesive by bonding using a conductive adhesive. That is, the metal cladding portions 121 of the plurality of metal plates 120 are electrically connected to each other to form the terminal portion 12 of the multilayer bus bar 10.

Further, as described above, the terminal 12 of the multilayer bus bar 10 may be provided with a connector. Therefore, the metal clad portion 121 of the metal plate 120 may be connected to the connector and electrically connected. By providing a connector, a plurality of metal plates 120 can be integrated into one.

In the FFC100, it is preferable that the metal plate 120 is surrounded by an adhesive 130. That is, as shown in Fig. 2B, it is preferable that the adhesive 130 is installed on both edges of the FFC100 in the X direction, and the ends of the FFC100 are bonded by the adhesive 130. However, the configuration of the end portion of the FFC100 in the X direction is not limited thereto. At the end of the FFC100 in the X direction, a part of the metal plate 120 is exposed by the organic resin films 110-1 and 110-2.

The thickness of the organic resin films 110-1 and 110-2 and the adhesive 130 is 0.01 mm or more and 0.05 mm or less, preferably 0.02 mm or more and 0.05 mm or less, and particularly preferably 0.02 mm or more and 0.04 mm or less.

The cross-sectional shape of the metal plate 120 is specifically a square as shown in Fig. 2B. When the metal plate 120 is a square, the long side of the rectangle is in a direction parallel to the organic resin films 110-1 and 110-2 (i.e., in the X direction), and the short side of the rectangle is perpendicular to the organic resin films 110-1 and 110-2. Make it the direction (ie, the Z direction). By configuring the metal plate 120 in this way, the area overlapping the metal plate 120 and the organic resin films 110-1 and 110-2 increases, and heat loss and current loss of the FFC100 to be described later can be reduced. In addition, the cross-sectional shape of the metal plate 120 is not limited to a square. The cross-sectional shape of the metal flat plate 120 may be, for example, an ellipse. In that case, the major axis of the ellipse is set in the X direction, and the major axis of the ellipse is set in the Z direction.

When the metal plate 120 is a square, the length of the long side relative to the length of the short side of the square is 5 times or more, preferably 10 times or more, particularly preferably 50 times or more. The difference between the length in the short side direction and the length in the long side direction of the square is increased, so that the area overlapping the metal plate 120 and the organic resin layers 110-1 and 110-2 can be increased even if the cross-sectional area has the same size. Therefore, as long as the rigidity of the metal plate 120 can be maintained, the length in the long side direction to the length in the short side direction may be 100 times or more.

Materials of the organic resin films 110-1 and 110-2 are, for example, polyethylene teretalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), or polycyclohexane dimethylene terephthalate (PCT). ) Can be used. As a material for the organic resin films 110-1 and 110-2 of FFC100, PCT is particularly preferable. PCT has higher chemical resistance than PET or PEN, and has excellent hydrolysis stability, electrical stability, and thermal stability.

Further, the thermal emissivity of the organic resin films 110-1 and 110-2 is 0.7 or more and 1 or less, preferably 0.75 or more and 1 or less, and particularly preferably 0.8 or more and 1 or less. Since the organic resin films 110-1 and 110-2 are provided on the outermost side of the FFC100, the heat emissivity of the organic resin films 110-1 and 110-2 is preferably greater than that of the metal plate 120 and the adhesive 130. In particular, it is preferable that the heat emissivity increases in the order of the metal plate 120, the adhesive 130, and the organic resin films 110-1 and 110-2. The heat dissipation efficiency is improved by increasing the heat emissivity to the outside of the FFC100.

The material of the metal plate 120 may be, for example, copper (Cu), silver (Ag), gold (Au), aluminum (Al), platinum (Pt), or an alloy thereof. Cu is particularly preferable as the material of the metal plate 120 of the FFC100. Since Cu has high electrical conductivity and is inexpensive, manufacturing cost can be suppressed.

As the material of the adhesive 130, for example, polyester, acrylic, epoxy, or the like can be used. Further, when the adhesive 130 is provided on the organic resin films 110-1 and 110-2, a primer may be applied to the organic resin films 110-1 and 110-2. If the primer is applied, the adhesion between the organic resin films 110-1 and 110-2 and the adhesive 130 is improved.

The stacked busbar 10 according to an embodiment of the present invention can reduce the amount of metal occupied as a whole compared to a busbar made of a bulk metal (hereinafter, referred to as a rigid busbar). Therefore, the laminated busbar 10 is lighter than the rigid busbar, and the cost can be reduced. In addition, since the stacked busbar 10 has a structure in which FFC100 is stacked, unlike the rigid busbar, it has excellent flexibility. Existing rigid busbars lose more power than when the rigid busbar is not bent because a significant amount of heat is generated in the folded portion when power is supplied if there is a bent portion. On the other hand, even when the stacked busbar is folded, there is almost no power loss due to the folding. Therefore, the stacked busbar 10 has many advantages over the rigid busbar.

In addition, the multilayer bus bar 10 can suppress an increase in temperature when a large current is passed. This can be explained by the fact that the stacked busbar 10 has less heat and current losses than the rigid busbar. Therefore, the heat loss and current loss mechanisms of the stacked busbar 10 will be described below.

[2. Heat loss]

The second law of thermodynamics relates to the direction of energy movement and the quality of energy, and also to entropy. For example, the electric heating wire heater may convert electrical energy into thermal energy. However, it gives heat energy to the heating wire heater and cannot be converted into electric energy. Therefore, when comparing electrical energy and thermal energy, electrical energy is of higher quality than thermal energy, and it is only possible to convert (transfer) from high-quality electrical energy to low-quality thermal energy.

In addition, in the transfer of heat energy, for example, hot coffee cools, but cold coffee does not become hot (heating more than the temperature of the air in which the coffee is placed). This is because the heat of hot coffee is transferred to the air, but the entropy increases as the heat energy diffuses into the air. In other words, it is possible for the thermal energy to move only in the direction in which the entropy increases.

If you think about the power of the busbar, all of the busbar supply power Pappli 　 is not extracted as the power Preal 　, but there is always a loss of electric energy and power loss 　 Ploss 　 occurs. This can be represented by (Equation 2).

[Wed 3]

As described above, high-quality electrical energy is converted into low-quality thermal energy by the second law of thermodynamics. Therefore, the power loss 　 Ploss 　 was converted from high-quality electrical energy to low-quality thermal energy. Therefore, the busbar has heat energy equal to the power loss 　 Ploss 　. This thermal energy is released to the outside of the busbar by heat transfer, that is, heat conduction, convection, and heat radiation.

Heat conduction is heat transfer through a material, and there is an inherent thermal conductivity of a material as a standard for ease of heat transfer of a material. Convection is the heat transfer by fluid flow. Heat radiation is heat transfer by electromagnetic waves, and has a specific heat emissivity as a standard for the ease of heat dissipation of a material. Here, it is considered that there is no influence of convection (for example, convection of air) in the environment in which the busbar is located, and heat conduction and heat dissipation are considered in the heat transfer of the busbar.

Heat conduction is expressed as (Equation 3) by Fourier's law.

[Wed 4]

Here, Q _F is the amount of heat transfer due to heat conduction, k is the thermal conductivity of the material, A is the cross-sectional area of the material, and ∇ T is the temperature gradient.

In addition, thermal radiation is expressed as (Equation 4) by Stefan Boltzmann's law.

[Wed 5]

Here, Q _SB is the amount of heat transfer due to thermal radiation, σ is the Stefan Boltzmann constant (= 5.67 Х 10 ^-8 (W/m ² · K ⁴ )), and T ₁ is the temperature of material 1. _{The actual heat emission is different from the temperature T 2} of the transferred material 2, and since material 1 is not a perfect blackbody, it is expressed as (Equation 5) according to the emissivity ε (0 <ε <1) of the material 1.

[Wed 6]

As can be seen from (Equation 3) and (Equation 5), when the thermal conductivity of the material is large, the thermal conductivity is large, and when the thermal radiation rate of the material is large, the thermal radiation increases. Therefore, it is desirable to use a conductor with high thermal conductivity and heat radiation rate as a bus bar.

In the case of rigid busbars, Cu is often used for metal bars. The thermal conductivity of Cu is about 400 (W / m · K) and high, but the thermal emissivity of Cu is very low about 0.03. This means that the heat transfer inside the Cu is fast, but the heat dissipation to the outside is very small. Therefore, in the case of a rigid busbar using Cu, heat is accumulated inside without radiating heat to the outside. Therefore, the temperature of the rigid busbar is prone to rise.

On the other hand, in the case of the laminated busbar 10, even when Cu is used for the metal plate 120, two organic resin films 110-1 and 110-2, and an adhesive 130 are used as materials in contact with the outside. As described above, the materials of the organic resin films 110-1 and 110-2 are organic resin materials such as PET, PEN, or PCT. The thermal conductivity of these organic resin materials is very low, 0.2~0.4 (W / m · K). On the other hand, the thermal emissivity of the organic resin material varies depending on the presence or absence of coloring, but is very high from 0.84 to 0.95. The same goes for adhesive 130.

_{Here, the heat transfer amount Q SB} by thermal radiation is calculated for each of the rigid busbar using Cu and the laminated busbar 10 using the metal plate 120 Cu using (Equation 5).

The cross-sectional area of a rigid busbar using a typical Cu with an allowable current of 300A is 90mm2. In addition, the thermal emissivity of Cu is 0.03. _{Therefore, the amount of heat transfer Q SB (Rigid)} due to heat radiation of the rigid busbar using Cu is expressed as follows.

[Wed 7]

On the other hand, the cross-sectional area of the multilayer bus bar 10 with an allowable current of 300 A is 38.4 mm 2. In addition, the metal plate 120 uses Cu (thermal emissivity: 0.03), the organic resin films 110-1 and 110-2 use PCT (thermal emissivity: 0.95), and the adhesive 130 uses epoxy (thermal emissivity: 0.84). The percentage pointed is 30% for Cu, 50% for PCT, and 20% for Epoxy. _{Therefore, the heat transfer amount Q SB (Laminated)} of the laminated busbar 10 due to heat radiation is expressed as follows.

[Wed 8]

As can be seen from the comparison between Q _{SB (Rigid)} and Q _{SB (Laminated)} , the stacked busbar 10 has about 10 times the amount of heat transfer compared to the rigid busbar. That is, it can be seen that the laminated busbar 10 has a very high heat dissipation effect compared to the rigid busbar.

In addition, in the case of the laminated busbar 10, the typical thickness of the organic resin films 110-1 and 110-2, and the adhesive 130 is very small, such as 0.02 to 0.04 mm, while the typical width of one metal plate 120 is very large, such as 1.6 mm. Therefore, even if the thermal conductivity of the organic resin films 110-1 and 110-2 is small, once heat conduction from the metal plate 120 occurs, heat accumulates in the organic resin films 110-1 and 110-2 due to the height of the thermal emissivity. No, it is released to the outside. Therefore, the temperature of the laminated busbar 10 is difficult to increase.

As can be seen from the above, from the viewpoint of heat loss, in the laminated bus bar 10 according to the embodiment of the present invention, a structure surrounding the metal plate 120 with a high thermal emissivity material is important. By simply inserting the metal flat plate 120 through the organic resin films 110-1 and 110-2, air enters and is trapped between them. Since the trapped air has a low heat emissivity of 0.024, the efficiency of external heat dissipation by heat radiation is lowered. Therefore, in the laminated busbar 10, the metal plate 120 is surrounded by an adhesive 130 having a high heat emissivity to prevent air intrusion, and the metal plate 120 and the organic resin films 110-1 and 110-2 are bonded through the adhesive 130. .

Here, the effect of the laminated busbar 10, the organic resin films 110-1 and 110-2, and the presence or absence of the adhesive 130 was verified using a simulation.

3A and 3B are side views and cross-sectional views showing the configuration of a simulation program of a stacked busbar 10 according to an embodiment of the present invention. Meanwhile, FIGS. 4A and 4B are side views and cross-sectional views showing the configuration of a bus bar simulation that does not include organic resin films 110-1 and 110-2, and an adhesive 130 as comparative examples.

Further, in this simulation, the structure of the laminated busbar 10 was further simplified, and the organic resin films 110-1 and 110-2, and the adhesive 130 were calculated as an integrated engineering plastic 140. In addition, engineering plastics 140 refer to plastics having high heat resistance.

In any case, Cu was used as the material of the metal plate 120, the width w of the metal plate 120 was 1.6 mm, and the thickness t was 0.2 mm. Further, the pitch d between the metal plates 120 was 1 mm. The length L of one FFC10 was 500 mm, and the number of metal plates 120 included in the other FFC10 was m = 5. In addition, the number of FFC layers was n = 40. As a result, the total cross-sectional area of the metal plate 120 was 64 (= 1.6 Х 0.2 Х 5 Х 40) mm 2.

As for the simulation conditions, the measurement start temperature was 25 degrees, and the amount of temperature increase at an applied current of 300 A was calculated.

The simulation results are shown in Table 1. Compared to the bus bars shown in Figs. 4A and 4B, the multilayer bus bar 10 shown in Figs. 3A and 3B had a smaller temperature increase. This indicates that the laminated busbar 10 has a structure that is easy to heat dissipation.

Stacked busbar shown in Fig. 3 Busbar shown in Figure 4 Temperature rise at measuring point P1 42.9 degrees 67.8 degrees Temperature rise at measuring point P2 41.8 degrees 74.0 degrees Maximum temperature increase 45.6 degrees 63.1 degrees

It was confirmed that the laminated busbar 10 according to the embodiment of the present invention has an easy-to-heat heat dissipation structure in the simulation. This is due to the high thermal emissivity of the adhesive 130 surrounding and in contact with the metal plate 120 and the organic resin films 110-1 and 110-2. When the temperature of the metal plate 120 increases, the resistance of the metal plate 120 increases, making it difficult for current to flow. As a result, it is also necessary to flow an electric current, and heat is also generated by the electric current. The stacked busbar 10 has a configuration that suppresses temperature rise and does not require a new current. Therefore, the stacked busbar 10 is a configuration capable of reducing heat loss.

[3. Current loss]

Next, the current loss of the stacked busbar 10 is examined. The power of the stacked busbar 10 is expressed by the above-described (Equation 1), and when the power loss 　Ploss is 　100 Х r% of the applied power 　 Pappli, the effective power Preal 　 can be expressed as (Equation 6).

[Equation 9]

Here, the active power Preal　 can also be expressed as (Equation 7) by using the current I and the resistance R.

[Equation 10]

As can be seen from (Equation 7), the active power Preal is ^{proportional to the square I 2} of the current, and also proportional to the work resistance R. Therefore, it can be seen that in order to enlarge the active power Preal, it is better to increase the current I.

On the other hand, the power loss 　Ploss is expressed as (Equation 8) when using the current I and the resistance R.

[Wed 11]

As the current I increases, the active power 　 Preal 　 increases, but as can be seen from (Equation 8), the power loss 　 Ploss also increases. Therefore, in the stacked busbar 10, it is necessary to consider the maximum current I in which the power loss Ploss is suppressed. This can be said to consider the maximum current I in which the current loss of the stacked busbar 10 is reduced.

(Equation 8) is ^{expressed as the product of the current squared I 2} and the resistance R. Here, ^{it is assumed that the power loss Ploss can be separated into the square I 2} component of the current and the resistance R component using the parameter x. The square of the current I ² and the resistance R are expressed as (Equation 9) and (Equation 10) using the parameter x, respectively.

[Wed 12]

Figure 5 shows the power loss Ploss, and ^{shows the respective graphs of the square of the current I 2} (x) and the resistance R (x) for the parameter x. The square of the current I ² and the resistance R are determined by the parameter x. As can be seen in the graph shown in Fig. 5, the _{point A 0 at which} ^{the curve of the square of current I 2} (x) and the straight line of the resistance R(x) change Exists. Both the area S smaller than the _{point A 0 and the area S'larger than the point A 0} are areas where the real power Preal is greater than the power loss Ploss. However, the current loss ploss factor is different. In the region S, the resistance R (x) ^{is larger than the square of the current I 2} (x). That is, in the region S, it can be said that the resistance component dominates in the power loss Ploss. On the other hand, in the _{region S'larger than the point A 0} , the square of the current I ² (x) is larger than the resistance R(x). That is, in the region S', it can be said that the current component dominates in the power loss Ploss. In other words, an _{area larger than point A 0} can be said to be a large area of current loss. Therefore, in the stacked busbar 10, the current loss can be reduced by using the value of the current I in the region S.

The value of x at point A ₀ can be obtained as follows.

[Wed 13]

In (Equation 11), the current flowing through the multilayer bus bar 10 is at x = 0 when the direct current is 0, but x ≠ 0 in the case of the alternating current. Therefore, in the case of an alternating current, the solution satisfying (Equation 11) becomes as (Equation 12).

[Wed 14]

_{Since C 1} and C ₂ in (Equation 12) are integers, they are considered in the integer C of (Equation 8). Therefore, the value of x ₀ at point A ₀ is represented by (equation 13).

[Wed 15]

Here, experimental measurements are made on the rigid busbar and the stacked busbar 10, and the difference in the characteristics of the stacked busbar 10 by the rigid busbar is expressed as a difference in physical quantity. In order to reduce the Ploss in the region S, the resistance component can be reduced. The magnitude of the resistance is inversely proportional to the cross-sectional area and proportional to the length. Therefore, _{as a physical quantity of x 0} , for example, a cross-sectional area or length can be used. Here, the _{cross-sectional area is used as the physical quantity of x 0} , and the difference in characteristics between the rigid busbar and the laminated busbar 10 is expressed using the cross-sectional area of the metal bar of the rigid busbar and the total cross-sectional area of the metal plate 120 of the laminated busbar 10. I can.

For example, if the temperature rise stays within a certain range and the cross-sectional area of the metal bar of the rigid busbar that can flow 300A is 90mm2, the total cross-sectional area of the metal plate 120 of the laminated busbar 10 is 38.4mm2 under the same conditions, experimentally. It was measured as.

In the case of reducing the current loss of the stacked busbar 10, a value of the parameter x smaller than _{x 0 in (Equation 13) may be selected.} Therefore, (Equation 13) a _1, b ₁ and b ₂ is to think that it is variable, and a ₁ and b ₁ are squared I ² component of the current in the (expression 9) and (equation 10) in b ₂ is the resistance R It can be seen that it is an ingredient. In the case of alternating current, the difference between the stacked busbar 10 and the rigid busbar is more ^{pronounced as the square I 2} component of the current rather than the resistance R component. Therefore, here, the resistance R component is considered to correspond to the rigid busbar, and b ₂ is replaced by the rigid busbar physical quantity. Therefore, by substituting the above-described measured value into (Equation 13), the value of x _{0 at point A 0} can be obtained as follows.

[Wed 16]

At least in the above conditions (the temperature rise is within a certain range and can flow 300A of current), if the total cross-sectional area of the metal plate 120 is x ≤1.34, it can be a stacked busbar 10 with reduced current loss. have.

In addition, when the values of the current supplied to the multilayer busbar 10 are different, the current value supplied by the FFC100 per layer is obtained, and the number of FFC100 layers n can be adjusted so that the current value is set.

[4. Laminated busbar design method]

As described above, the stacked busbar 10 can reduce heat loss and at the same time reduce current loss. Hereinafter, a method of designing a stacked busbar 10 in which heat loss and current loss are reduced will be described. However, the design method of the laminated busbar 10 is not limited to the following method.

In order to reduce heat loss, the structural design of the laminated busbar 10, organic resin films 110-1 and 110-2, and selection of materials for the adhesive 130 are important. Specifically, in the stacked busbar 10, n-layer FFC100 is stacked. M number of metal plates 120 are disposed between the organic resin films 110-1 and 110-2 having high FFC100 thermal emissivity. The metal plate 120 is adhered to the organic resin films 110-1 and 110-2 through an adhesive 130 having a high thermal emissivity, but the adhesive 130 is disposed so as to surround the metal plate 120. In addition, the metal plate 120 is arranged so that the long sides of the metal plate 120 are parallel to the organic resin films 110-1 and 110-2, and the area where the metal plate 120 and the organic resin films 110-1 and 110-2 overlap is large. Let it go. The laminated busbar 10 can be designed with the above-described structure and material cost to reduce heat loss.

Meanwhile, in order to reduce the current loss, it is important to design the structure of the metal plate 120 and to select a material. The metal plate 120 is made of a metal plate 120 with high conductivity in order to reduce resistance. In addition, in the structural design of the metal plate 120, the physical quantity of the metal plate 120 corresponding to the physical quantity of the metal bar of the rigid busbar is obtained by experimental measurement under specific conditions. Specific conditions include current value (e.g., 300A), temperature rise (e.g., 100), and a specific value (point A value) from the physical quantity of the metal bar of the rigid busbar and the physical quantity of the metal plate 120, and the metal The structure of the metal plate 120 is designed so that the physical quantity of the plate 120 is less than a certain value. As the physical quantity, for example, a cross-sectional area can be used. The laminated busbar 10 can be designed with the above-described metal plate 120 structure and material to reduce current loss.

As described above, the laminated busbar 10 has a structure in which a plurality of metal plates 120 are disposed between the organic resin films 110-1 and 110-2, and a plurality of FFC100 fixed by an adhesive 130 are laminated. Since the organic resin films 110-1 and 110-2 and the adhesive 130 have high thermal emissivity, heat dissipation is easy, and heat loss is reduced. In addition, by comparing the physical quantities of the laminated busbar 10 and the rigid busbar, it is possible to design a laminated busbar 10 in which m number of metal flat plates with reduced current loss and n-layer FFC100 are laminated.

<Second Embodiment>

A stacked busbar 10A different from the stacked busbar 10 according to the first embodiment will be described with reference to FIG. 6.

6 is a schematic side view of a stacked busbar 10A according to an embodiment of the present invention. The stacked busbar 10A includes two types of FFC100a and 100b. In addition, as shown in Fig. 6, the two types of FFC100a and 100b are FFC100a-1, 100b-1, 100a-2, ... , 100a-n, 100b-n and stacked alternately. That is, the stacked busbar 10A of FIG. 6 includes an n-layer FFC100a and an n-layer FFC100b.

The FFC100a includes a plurality of metal flat plates 120a between two organic resin films 110-1 and 110-2. That is, FFC100a is a plurality of metal plates 120a-1, 120a-2, ... in the Y direction. , 120a-ma　 and ma　 number of metal plates 120a are arranged. Further, the FFC100b includes a plurality of metal flat plates 120b between the two organic resin films 110-1 and 110-2. That is, FFC100b is a plurality of metal plates 120b-1, 120b-2, ... in the Y direction. , 　120b-mb　 and 　mb　 metal plates 120a are arranged.

The stacked busbar 10A shown in Fig. 6 does not overlap with the FFC100a metal plate 120a and the FFC100b metal plate 120b in the Z direction. That is, ma number of metal plates 120a included in one FFC100a and mb number of metal plates 120b included in one FFC100b have a relationship ma=mb+1. However, the number of the metal plate 120a and the metal plate 120b is not limited thereto. The number of the metal plate 120a and the metal plate 120b may be, for example, ma=2mb+1. This means that two metal plates 120b are installed in the FFC100b, overlapping with the region between the adjacent metal plates 120a in the FFC100a.

In addition, as a modified example of the stacked busbar 10A, the stacked busbar 10A may partially overlap the FFC100a metal plate 120a and the FFC100b metal plate 120b in the Z direction. That is, the end of the metal plate 120a and the end of the metal plate 120b overlap each other.

In addition, as another modified example of the stacked busbar 10A, a configuration different from a pitch between adjacent metal plates 120a of FFC100a and a pitch between adjacent metal plates 120b of FFC100b is also possible. In this case, it is possible to partially overlap the FFC100a metal plate 120a and the FFC100b metal plate 120b in the Z direction without completely overlapping. In addition, a configuration different from the width of the metal plate 120a of the FFC100a and the width of the metal plate 120b of the FFC100b is possible. Even in this case, the FFC100a metal plate 120a and the FFC100b metal plate 120b may not be completely overlapped in the Z direction, but may be partially overlapped.

As described above, the stacked busbar 10A has a structure in which FFCs having different arrangement pitches or widths of metal plates are alternately stacked, including a modified example. By slowing the overlapping of the metal plates in the stacking direction of the FFC (Z direction), the influence between the metal plates can be eliminated. For example, when high-frequency alternating current is passed through a metal plate, the alternating current flowing through the metal plate forms a magnetic field, and an eddy current is generated by the magnetic field. In the stacked busbar 10A, the overlapping of the metal plates is misaligned, and the other side is difficult to be affected by the magnetic field formed on one side of the adjacent metal plates. Therefore, the laminated busbar 10A can reduce the eddy current of the metal plate. Therefore, the stacked busbar 10A heat loss is not only reduced, but also the current loss is low or reduced.

<Third embodiment>

A battery module 20 to which the stacked busbar 10 according to the first embodiment is applied will be described with reference to FIG. 7.

7 is a schematic perspective view of a battery module 20 according to an embodiment of the present invention. The battery module 20 includes a first battery unit 200-1, a second battery unit 200-2, a third battery unit 200-3, and a fourth battery unit 200-4. In the following, when the first battery unit 200-1, the second battery unit 200-2, the third battery unit 200-3, and the fourth battery unit 200-4 are not particularly distinguished, the description will be made as a battery unit 200. .

The battery unit 200 includes a plurality of battery cells 210. In addition, each of the plurality of battery cells 210 includes a + electrode 220-1 and a-electrode 220-2. Two adjacent battery cells 210 of one battery unit 200 are connected in series with the + electrode 220-1 and the-electrode 220-2 electrically connected by a first stacked bus bar 10-1.

In addition, the first battery cell 210-1, the second battery cell 210-2, the third battery cell 210-3, and the fourth battery cell 210-4 are electrically connected by a second stacked bus bar 10-2. In addition, the second battery cell 210-2 and the third battery cell 210-3 are electrically connected by a third stacked bus bar 10-3.

The lengths of the first stacked busbar 10-1, the second stacked busbar 10-2, and the third stacked busbar 10-3 may be changed depending on the connection position. In addition, the number of stacks of FFC100 included in the stacked busbar 10 may be changed, or the number of metal plates 120 included in the FFC100 may be changed.

In addition, the first laminated busbar 10-1, the second laminated busbar 10-2, and the third laminated busbar 10-3 shown in FIG. 7 are drawn in a straight line for convenience, but the laminated busbar 10 has flexibility. , Can be installed in a curved line. Accordingly, it is possible to process the stacked bus bar 10 into various shapes and electrically connect between a plurality of battery units 200 or between a plurality of battery cells 210. Accordingly, it is possible to electrically connect between the plurality of battery units 200 or between the plurality of battery cells 210 by using a small space in the battery pack accommodating the battery module 20.

As described above, by using the stacked bus bar 10 for the battery module 20, it is possible to electrically connect even in a narrow space. In addition, the degree of freedom of electrical connection of the battery unit 200 or the battery cell 210 increases, so that the degree of freedom in the arrangement of the battery unit 200 or the battery cell 210 increases. In addition, since the laminated busbar 10 has a high heat dissipation effect, heat can be radiated through the thermally laminated busbar 10 generated from the battery cell 210.

The battery module 20 can be used, for example, in an electric vehicle (EV), a hybrid electric vehicle (HEV), or a plug-in hybrid electric vehicle (PHEV). Since the stacked busbar 10 of the battery module 20 is lightweight, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle using the battery module 20 has a longer cruising distance.

Each of the embodiments of the present invention can be implemented in appropriate combinations within a range that does not contradict each other. Further, based on the stacked busbars of each embodiment, those skilled in the art appropriately add, delete or modify constituent elements are also included in the scope of the present invention having the gist of the present invention.

In addition, other operational effects that are different from the operational effects caused by the respective embodiments of the present invention are obvious from the description of the present specification, or can be easily predicted by those skilled in the art, and are naturally interpreted as being brought about by the present invention.

10, 10A: laminated busbar, 10-1: first laminated busbar, 10-2: second laminated busbar, 10-3: three laminated busbar, 11: main body, 12: terminal portion, 20: battery module, 100,100a,100b: flexible flat cable (FFC), 110-1, 110-2: organic resin film, 120,120a, 120b: metal flat plate, 121: metal clad portion, 130: adhesive, 140: engineering plastic, 200: battery Unit, 200-1: first battery unit, 200-2: second battery unit, 200-3: third battery unit, 210: battery cell, 210-1: first battery cell, 210-2: second battery Cell, 210-3: third battery cell, 210-4: fourth battery cell, 220-1: + electrode, 220-2:-electrode

Claims (15)

It is a laminated busbar in which a plurality of flexible flat cables (FFC) are stacked,
Each of the plurality of flexible flat cables (FFC)
Two organic resin films,
Including a plurality of metal plates between the two organic resin films and an adhesive for bonding the two organic resin films and the plurality of metal plates,
The adhesive is installed between the adjacent metal plates,
Each of the two organic resin films and the adhesive has a thermal emissivity higher than that of the metal plate. It is a laminated busbar in which a plurality of flexible flat cables (FFC) are stacked, each of the plurality of flexible flat cables (FFC),
Two organic resin films,
A plurality of metal flat plates between the two organic resin films,
Including an adhesive for bonding the two organic resin films and the plurality of metal plates,
The adhesive is installed between the adjacent metal plates,
Two adjacent flexible flat cables (FFC) among the plurality of flexible flat cables (FFC) have different numbers of the plurality of metal plates included in each,
Each of the two organic resin films and the adhesive has a thermal emissivity higher than that of the metal plate. The laminated busbar according to claim 1 or 2, wherein the thermal emissivity of the two organic resin films is 0.8 or more. The laminated busbar according to any one of claims 1 to 3, wherein the material of the two organic resin films is polycyclohexane dimethylene terephthalate (PCT). The laminated busbar according to any one of claims 1 to 4, wherein the material of the adhesive is polyester. The laminated busbar according to any one of claims 1 to 5, wherein the metal flat plate is a square, and the length of the long side of the square is 5 times or more of the length of the short side of the square. A physical quantity of the metal bar obtained under predetermined conditions of a rigid busbar using the material of the metal plate as a metal bar, and a specific value obtained by using the physical quantity of the metal plate corresponding to the physical quantity of the metal bar, The laminated busbar according to any one of claims 1 to 6, wherein the structure of the metal plate is determined by using the physical quantity of the metal plate as a parameter. The physical quantity of the metal bar is the cross-sectional area A ₁ of the metal bar,
_{The physical quantity of the metal plate is the total cross-sectional area A 2} of the plurality of metal plates included in the laminated plurality of flexible flat cables (FFC),
The laminated busbar according to claim 7, wherein the total cross-sectional area A _{2 of the plurality of metal flat plates satisfies the following equation.}
[Wed 1]

The laminated bus bar according to claim 8, wherein the cross-sectional area A _{1 of the metal bar is 90 mm 2.} A first battery cell,
A second battery cell,
Including a stacked busbar electrically connecting the electrode of the first battery cell and the electrode of the second battery cell, and stacking a plurality of flexible flat cables (FFC),
Each of the plurality of flexible flat cables (FFC),
Two organic resin films,
A plurality of metal flat plates between the two organic resin films,
Including an adhesive for bonding the two organic resin films and the plurality of metal plates,
The adhesive is installed between the adjacent metal plates,
Each of the two organic resin films and the adhesive has a thermal emissivity higher than that of the metal plate. The first battery cell is included in the first battery unit,
The second battery cell is the battery module according to claim 10 included in a second battery unit different from the first battery unit The battery module according to claim 10 or 11 used in an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle A laminated bus in which a plurality of flexible flat cables (FFCs) including two organic resin films, a plurality of metal plates between the two organic resin films, and an adhesive bonding the two organic resin films and the plurality of metal plates are laminated In the bar design method,
Acquiring the physical quantity of the metal bar under predetermined conditions of a rigid bus bar using the material of the metal plate as a metal bar,
Acquiring the physical quantity of the metal flat plate under the predetermined condition of the stacked busbar,
A specific value is calculated using the physical quantity of the metal bar and the physical quantity of the metal plate,
A method of designing a stacked busbar in which the structure of the metal plate is determined through a physical quantity of the metal plate so that it is less than or equal to the specific value. The physical quantity of the metal bar is a cross-sectional area A ₁ of the metal bar,
_{The physical quantity of the metal plate is the total cross-sectional area A 2} of the plurality of metal plates included in the plurality of stacked flexible flat cables (FFC),
The method of designing a laminated busbar according to claim 13, wherein the structure of the metal plate is determined so as to satisfy the following equation using _{the total sectional area A 2} of the plurality of metal plates as a parameter.
[Wed 2]

The design method of the laminated busbar according to claim 14, wherein the cross-sectional area A _{1 of the metal bar is 90 mm 2.}

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