JP2017216845A - Electric unit of electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric unit of an electric vehicle, which can suppress both the electromagnetic noise caused by a current in a normal mode and the electromagnetic noise caused by a current in a common mode and, in addition, can suppress the generation of an intense heat without deteriorating the degree of freedom in wiring layout of bus bars.SOLUTION: An electric unit (1) of an electric vehicle comprises a plurality of electric components (10, 20, 30) mounted on the electric vehicle, a plurality of bus bars (2, 3) letting currents flow between the plurality of electric components, cooling bars (4A, 4B) that are plate-shaped members having electric conductivity and thermal conductivity, holding bodies (5A, 5B) having an insulation property and thermal conductivity and holding the plurality of bus pars and the cooling bars in parallel to each other at least in a partial range, and metal structural bodies (6A, 6B) accommodating or supporting the plurality of electric components. In the cooling bars, at least one parts are thermally connected to the structural bodies and at least two parts spaced apart from each other are connected to the structural bodies in a conductive or alternating-current conductive manner.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric unit of an electric vehicle.

  The electric vehicle includes a plurality of electrical components such as a battery, an inverter, and a motor, through which high voltage is applied and a large current flows. These electrical components may be connected to each other through a bus bar that is a plate-like conductor. In such a configuration, if no countermeasure is taken, a large electromagnetic noise is generated due to a large current. Note that the bus bar originally includes the meaning of a bus bar that distributes current to a plurality of conductors, but in this specification, a conductor that is configured in a plate shape and efficiently flows a large current is referred to as a bus bar. Call.

  A technique for reducing electromagnetic noise radiated from a bus bar by arranging a plurality of bus bars to face each other in a predetermined combination has been known. For example, when a P bus bar connected to the anode of the battery and an N bus bar connected to the cathode are arranged to face each other, currents having the same current value flow in the P bus bar and the N bus bar, respectively, and opposite to each other. Therefore, the magnetic field generated by the current of the P bus bar and the magnetic field generated by the current of the N bus bar cancel each other, and electromagnetic noise is reduced.

  On the other hand, when a plurality of bus bars are arranged close to each other, there is a problem that heat generated by a large current is concentrated and this portion is heated. As a technique for solving such a heat problem, Patent Document 1 discloses a structure in which a plurality of bus bars are bundled and cooled by a heat sink. Patent Document 2 discloses a bus bar set in which a plurality of bus bars are arranged so that their plate surfaces are aligned on the same plane, and intermediate portions of the plurality of bus bars are covered with an insulating member.

  As a technique for improving the electromagnetic noise resistance of an electric vehicle, Patent Document 3 discloses a three-phase inverter device that allows a capacitor case to function as an electromagnetic shield.

Japanese Patent Laid-Open No. 06-351109 JP 2012-182047 A Japanese Patent Laid-Open No. 11-136960

  As described above, electromagnetic noise can be reduced by arranging a plurality of bus bars to face each other in a predetermined combination. In this case, the electromagnetic noise is further reduced as the plurality of bus bars are brought closer to each other. On the other hand, in consideration of heat problems, it is preferable that the plurality of bus bars are not so close to each other. Thus, they are in a trade-off relationship.

  On the other hand, by taking measures against heat, a plurality of bus bars can be arranged close to each other. However, as shown in Patent Document 1, in a configuration in which heat dissipation is performed using a heat sink, a large space is required for arranging the heat sink. Moreover, when the bus bar is long and cooling is required in a plurality of sections of the bus bar, a plurality of such spaces are required. In addition, in the configuration in which a plurality of bus bars are spread and arranged as shown in Patent Document 2, it is difficult to arrange the bus bars in a compact manner. Therefore, when these configurations are adopted, the degree of freedom of the bus bar wiring layout is reduced, and it becomes difficult to arrange the bus bar in a limited space.

  By the way, in the method of arranging a plurality of bus bars so as to face each other in a predetermined combination, it is possible to reduce electromagnetic noise caused by the current in the normal mode. However, high-frequency common mode current may be mixed in the bus bar as noise. The common mode current is generated due to, for example, the operation of the inverter. When such a current is mixed, high-frequency electromagnetic noise that easily affects the sensor or the electric circuit is generated. Since the common mode current flows in the same direction through the plurality of bus bars, electromagnetic noise is not reduced even if the plurality of bus bars are arranged close to each other.

  The present invention can suppress both electromagnetic noise caused by the normal mode current and electromagnetic noise caused by the common mode current, and in addition, the generation of high heat can be suppressed without lowering the degree of freedom of the bus bar wiring layout. An object is to provide an electric unit of an electric vehicle.

The invention described in claim 1
A plurality of electrical components mounted on an electric vehicle;
A long plate-like metal member along the current path, and a plurality of bus bars for passing a current between the plurality of electrical components;
A cooling bar that has electrical conductivity and thermal conductivity and is a long plate-like member along a predetermined path;
A holding body having insulation and thermal conductivity, and holding the plurality of bus bars and the cooling bar in parallel at least in a part of the range;
A metal structure that houses or supports the plurality of electrical components;
With
The cooling bar is an electric unit of an electric vehicle in which at least one place is thermally connected to the structure and at least two places separated from each other are connected to the structure in a conductive or alternating manner.

The invention according to claim 2 is the electric unit of the electric vehicle according to claim 1,
Both ends of the cooling bar are connected to the structure, and the cooling bar and a part of the structure constitute an electrical closed circuit.

The invention according to claim 3 is the electric unit of the electric vehicle according to claim 1 or 2,
The plurality of bus bars are configured to pass current between two electrical components,
2. The structure according to claim 1, wherein the holding body holds the plurality of bus bars and the cooling bar side by side in this order, and the cooling bar is disposed on the structure side of the plurality of bus bars. .

The invention according to claim 4 is the electric unit of the electric vehicle according to claim 1 or 2,
The plurality of bus bars include a first system bus bar that allows a current to flow between two electric components of a first set among three or more electric components, and the first set of three or more electric components. And a second system of bus bars that conduct current between two different sets of two electrical components,
The holding body is configured to hold the first system bus bar, the cooling bar, and the second system bus bar in this order.

According to a fifth aspect of the present invention, in the electric unit of the electric vehicle according to any one of the first to fourth aspects,
The holder is made of a material having a thermal conductivity higher than that of air,
The plurality of bus bars and the cooling bar are embedded in the holding body.

  According to the present invention, the cooling bar thermally connected to the structure is held in parallel with the plurality of bus bars at least partially. Therefore, a plurality of bus bars can be cooled without greatly reducing the degree of freedom of the bus bar wiring layout. Further, since the plurality of bus bars are cooled by the cooling bar, the plurality of bus bars can be arranged close to each other. As a result, electromagnetic noise caused by the normal mode current can be reduced. In addition, two spaced locations of the cooling bar are connected to the structure in a conductive or alternating manner. Therefore, when a common mode high-frequency current flows through a plurality of bus bars, a current that cancels the current can flow through the cooling bar. Thereby, the electromagnetic noise resulting from the common mode current can also be reduced.

1 is a partially broken schematic view showing an electric unit of an electric vehicle according to an embodiment of the present invention. It is a partially broken perspective view which shows the holding structure and arrangement example of a bus-bar and a cooling bar, (A) shows a 1st example, (B) shows a 2nd example. It is a figure explaining the effect | action by which the electromagnetic noise resulting from a common mode electric current is reduced, (A) is explanatory drawing when a cooling bar exists, (B) is explanatory drawing when there is no cooling bar.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partially broken schematic view showing an electric unit of an electric vehicle according to an embodiment of the present invention. FIG. 2A is a partially broken perspective view showing a holding structure of a bus bar and a cooling bar and a first arrangement example of the cooling bar. FIG. 2B is a partially broken perspective view showing a holding structure of the bus bar and the cooling bar and a second arrangement example of the cooling bar.

  The electric unit 1 of the present embodiment is a unit that is mounted on an electric vehicle and outputs electric power for traveling to a motor. The electric unit 1 includes a plurality of electric components (10, 20, 30), bus bars 2, 3, cooling bars 4A, 4B, bus bar cases 5A, 5B, a metal housing 6A, a metal frame 6B, and a cable 8. The bus bar cases 5A and 5B correspond to an example of the holding body according to the present invention. The metal housing 6A and the metal frame 6B correspond to an example of a metal structure according to the present invention.

  The electrical components (10, 20, 30) are high-voltage components that handle power for traveling. In this embodiment, as an example of an electrical component, a battery 10 that accumulates electric power for traveling, an inverter 20 that converts a DC voltage of the battery 10 into a three-phase AC voltage, and a three-phase AC voltage that is output to the motor via the cable 8. A terminal block 30 is applied.

  The bus bars 2 and 3 are long plate-like members along the current path, and are made of a metal member such as aluminum or copper. The electric unit 1 of the present embodiment includes three bus bars 2 of the first system connected between the battery 10 and the inverter 20, and three of the second system connected between the inverter 20 and the terminal block 30. And a bus bar 3. The battery 10 and the inverter 20 correspond to a first set of two electrical components, and the inverter 20 and the terminal block 30 correspond to a second set of two electrical components.

  The two bus bars 2 of the first system are electrically connected to the anode and the cathode of the battery 10, respectively, and a direct current flows between the battery 10 and the inverter 20. The two bus bars 2 of the first system are arranged close to each other in parallel so that their plate surfaces face each other. The two bus bars 2 do not have to be arranged in this way in the entire range, and may be arranged in this way in a range of more than half along the longitudinal direction.

  The three bus bars 3 of the second system are respectively connected to the three-phase output terminals of the inverter 20, and a three-phase alternating current flows between the inverter 20 and the terminal block 30. The three bus bars 3 of the second system have their plate surfaces facing the same direction, and the three bus bars 3 are juxtaposed in a direction perpendicular to the plate surfaces. The three bus bars 3 do not need to be arranged in this way in the entire range, and may be arranged in this way in a range of more than half along the longitudinal direction.

  The cooling bars 4A and 4B are electrically conductive and thermally conductive, and are long plate-like members along a predetermined path. The cooling bars 4A, 4B may have a higher thermal conductivity than the bus bar cases 5A, 5B, and in addition, may have the same conductivity as the bus bars 2, 3. The cooling bars 4A and 4B can be made of a metal member such as aluminum or copper.

  In this embodiment, one cooling bar 4A is provided corresponding to the two bus bars 2 of the first system, and one cooling bar 4B is provided corresponding to the three bus bars 3 of the second system. . The cooling bar 4A is disposed along the plurality of bus bars 2 of the first system in at least a part of the range. In the range along the bus bar 2, the cooling bar 4 </ b> A is arranged in parallel with the two bus bars 2 with the plate surface facing the plate surface of one bus bar 2. The cooling bar 4 </ b> A may be arranged along the bus bar 2 in this way in a range of half or more along the longitudinal direction of the bus bar 2. Both ends of the cooling bar 4A are connected to the metal frame 6B.

  The other cooling bar 4B is similarly arranged corresponding to the bus bar 3 of the second system. Both ends of the cooling bar 4B are connected to the metal frame 6B.

  The bus bar cases 5A and 5B are members that hold the bus bars 2 and 3 and the cooling bars 4A and 4B. The bus bar cases 5A and 5B have a thermal conductivity higher than that of air, and further have an insulating property. As a material of the bus bar cases 5A and 5B, for example, a resin such as polypropylene or polypropylene terephthalate, or a high thermal conductive resin in which a thermal conductive filler is blended with these can be applied.

  As shown in FIG. 2A, the bus bar case 5A holds the plurality of bus bars 2 and the cooling bars 4A close to each other in at least a part of the range. In the bus bar case 5A, the plurality of bus bars 2 and the cooling bar 4A are arranged in this order. The bus bar case 5A may hold the plurality of bus bars 2 and the cooling bars 4A in this way in a range that is more than half of the length of the plurality of bus bars 2 in the longitudinal direction.

  A plurality of bus bars 2 and cooling bars 4A are embedded in the bus bar case 5A. Such a configuration can be achieved by insert molding or the like. Alternatively, as shown in FIG. 2A, the bus bar case 5A may have a plurality of grooves, and a plurality of bus bars 2 and cooling bars 4A may be fitted in these grooves. In this case, the groove width is configured to be large, and a material having high thermal conductivity is sandwiched between the plurality of bus bars 2 and the inner surface of the groove, and between the cooling bar 4A and the inner surface of the groove. It is good also as composition to do.

  Similarly, the other bus bar case 5B holds a plurality of bus bars 3 and cooling bars 4B. In the bus bar case 5B, the three bus bars 3 and the cooling bar 4B are arranged in this order.

  In addition, you may employ | adopt the bus-bar case 5C as shown to FIG. 2 (B). FIG. 2B shows a case where a wiring layout in which the first system bus bar 2 and the second system bus bar 3 are close to each other in parallel is adopted for convenience of the wiring layout. In this case, the bus bar case 5C holds the first system bus bar 2, the second system bus bar 3, and the cooling bar 4C in parallel. In the bus bar case 5C, the plurality of bus bars 2 of the first system, the cooling bar 4C, and the plurality of bus bars 3 of the second system are preferably arranged in this order. With such an arrangement, the cooling bar 4C functions as an electromagnetic shield between the plurality of bus bars 2 in the first system and the plurality of bus bars 3 in the second system. Thereby, electrical interference (inductive coupling) between the first system bus bar 2 and the second system bus bar 3 can be reduced.

  The metal housing 6A accommodates a plurality of electrical components (10, 20, 30), a plurality of bus bars 2, 3, cooling bars 4A, 4B, and bus bar cases 5A, 5B. The metal frame 6B supports a plurality of electrical components (10, 20, 30). The metal housing 6A and the metal frame 6B may be electrically connected to the body ground of the electric vehicle. Instead of the metal housing 6A, a resin housing covered with an electromagnetic shielding material may be employed. Alternatively, the metal frame 6B may be omitted, and a plurality of electrical components (10, 20, 30) may be supported on the metal housing 6A.

  In FIG. 1, for simplification, the bus bars 2 and 3 and the cooling bars 4A and 4B are shown in a straight line, and the bus bar cases 5A and 5B are shown in a rectangular parallelepiped shape. However, normally, the bus bars 2 and 3 are bent along an arbitrary route due to requirements on the wiring layout. In this case, the cooling bars 4A and 4B and the bus bar case 5A are configured to be bent along the paths of the bus bars 2 and 3, respectively. In addition, the conductors connecting the plurality of electrical components (10, 20, 30) do not need to be configured by the bus bar in the entire section, and a cable may be sandwiched between some sections.

<Effects of heat dissipation and electromagnetic noise reduction>
Then, the effect | action of the thermal radiation of the electric unit 1 of embodiment and electromagnetic noise reduction is demonstrated. In the present embodiment, the plurality of bus bars 2 of the first system are held in the bus bar case 5A in parallel with the cooling bar 4A. Further, the plurality of bus bars 3 of the second system are held in the bus bar case 5B in parallel with the cooling bar 4B. Therefore, Joule heat generated in the plurality of bus bars 2 is transmitted to the bus bar case 5A, the cooling bar 4A, and the metal frame 6B and is dissipated. Similarly, Joule heat generated in the plurality of bus bars 3 is transmitted to the bus bar case 5B, the cooling bar 4B, the metal frame 6B, and the metal housing 6A and is dissipated to the outside. As described above, the plurality of bus bars 2 and 3 are efficiently cooled by dissipating heat to the cooling bars 4A and 4B in many sections in the longitudinal direction.

  Furthermore, in this embodiment, since the several bus-bars 2 and 3 are cooled efficiently, the several bus-bars 2 and 3 can be arrange | positioned closely for every system | strain. And by such arrangement | positioning, the electromagnetic noise resulting from the electric current of the normal mode which flows into the several bus-bars 2 and 3 can be reduced. Specifically, since currents in opposite directions flow through the two bus bars 2, when the two bus bars 2 come close to each other, magnetic fields generated by these currents cancel each other and electromagnetic noise is reduced. Further, a three-phase alternating current that becomes zero when added to the three bus bars 3 flows. Therefore, when the three bus bars 3 come close to each other, magnetic fields generated by these currents cancel each other and electromagnetic noise is reduced.

  Furthermore, in this embodiment, cooling bars 4A and 4B are provided along the plurality of bus bars 2 and 3, and both ends of the cooling bars 4A and 4B are connected to the metal frame 6B. As a result, electromagnetic noise caused by a common mode current flowing through each of the plurality of bus bars 2 and 3 can be reduced. Next, the reason will be described.

  FIGS. 3A and 3B are diagrams for explaining the action of reducing electromagnetic noise caused by the common mode current. FIG. 3A is an explanatory diagram when there is a cooling bar, and FIG. 3B is an explanatory diagram when there is no cooling bar. It is.

  An electrical component to which a high voltage is applied is capacitively connected to a nearby conductor via a parasitic capacitance. In the example of FIG. 3, the battery 10 and the inverter 20 are capacitively connected to the metal frame 6B via parasitic capacitances C101 and C102. Further, in the inverter 20, the power transistor is switched on and off at high speed. In such a configuration, as shown in FIGS. 3A and 3B, common-mode currents in the same direction flow as high-frequency noise through the plurality of bus bars 2 via the parasitic capacitances C101 and C102. In FIGS. 3A and 3B, a common mode current is indicated by an alternate long and short dash line arrow.

  As shown in FIG. 3 (B), when there is no cooling bar 4A, the common mode current that flows through the plurality of bus bars 2 travels through the metal frame 6B and flows from the battery 10 to the inverter 20 or vice versa. Therefore, the area S1 of the common mode current loop is increased. As the area of the closed loop through which the alternating current flows increases, the magnetic flux generated by the alternating current increases. Therefore, in the configuration of FIG. 3B, relatively large electromagnetic noise is generated.

  On the other hand, when the cooling bar 4A is provided on the metal frame 6B side of the plurality of bus bars 2 as shown in FIG. 3A, the high-frequency common mode current flowing through the plurality of bus bars 2 is greater than that of the metal frame 6B. It flows back to the cooling bar 4A. This is because the closed circuit passing through the cooling bar 4A has a lower impedance than the closed circuit passing through the metal frame 6B. Both impedances differ by the magnitude of the closed circuit inductance. The inductance is smaller when the loop area of the closed circuit is smaller. For this reason, the closed circuit passing through the cooling bar 4A has a lower impedance.

  Therefore, in the electric unit 1 of this embodiment, as shown in FIG. 3A, the common mode current flowing through the plurality of bus bars 2 returns via the cooling bars 4A arranged in parallel with the plurality of bus bars 2. Accordingly, the area S0 of the common mode current loop is reduced, and electromagnetic noise caused by the area is reduced.

  The same applies to the bus bar 3 and the cooling bar 4B of the second system.

  As described above, according to the electric unit 1 of the present embodiment, the cooling bars 4A and 4B arranged in parallel with the bus bars 2 and 3 absorb Joule heat from many ranges of the bus bars 2 and 3, and the metal bars are used to absorb the Joule heat. It can be guided to 6B and dissipated from the metal housing 6A to the outside. Since the bus bars 2 and 3 are disposed in a space that is substantially sealed by the metal casing 6A, heat radiation to the outside of the metal casing 6A is very effective.

  Further, the plurality of bus bars 2 and 3 and the cooling bars 4A and 4B have a long plate-like configuration along a predetermined path, and in addition, are arranged in parallel so that their plate surfaces face each other. Therefore, even if the cooling bars 4A and 4B are included, these configurations can be made compact, and the layout flexibility of the bus bars 2 and 3 does not decrease so much.

  Furthermore, since the bus bars 2 and 3 and the cooling bars 4A and 4B can be manufactured by the same manufacturing process, the manufacturing cost can be kept low. Further, the two bus bars 2 and the cooling bar 4A can be integrally formed by a bus bar case 5A. Further, the three bus bars 3 and the cooling bar 4B can be integrally formed by a bus bar case 5B. These improve the workability of assembling the bus bars 2 and 3 and the cooling bars 4A and 4B in the assembly process of the electric unit 1.

  In addition, according to the electric unit 1 of the present embodiment, as described above, both the electromagnetic noise caused by the normal mode current flowing in the bus bars 2 and 3 and the electromagnetic noise caused by the common mode current are reduced. can do.

  The embodiments of the present invention have been described above. However, the present invention is not limited to this. For example, in the said embodiment, the structure which connected the both ends of cooling bar 4A, 4B to the metal frame 6B was shown. However, at least one part of the cooling bars 4A and 4B may be thermally connected to the metal structure, and at least two parts separated from each other may be connected to the metal structure in a conductive or alternating manner. . The thermal connection means an aspect including not only a direct connection but also a connection capable of transferring heat to the same extent as a direct connection, such as a connection through a member having high thermal conductivity. The AC connection includes not only a direct connection but also a connection that allows a common mode current to flow to the same extent as a direct connection, for example, a surface contact through a thin insulating member. Means an aspect.

  In the above-described embodiment, an example in which a battery, an inverter, and a terminal block are applied as a plurality of electric components has been described. However, various electric components to which high voltage is applied such as a traveling motor, a generator, and a converter are applied. May be. In this specification, an electric vehicle may be read as a hybrid electric vehicle or an electric vehicle.

1 Electric unit 2, 3 Bus bar 4A, 4B Cooling bar 5A, 5B, 5C Bus bar case (holding body)
6A Metal enclosure (structure)
6B Metal frame (structure)
10 Battery (electrical parts)
20 Inverter (electric parts)
30 Terminal block (electrical parts)

Claims (5)

A plurality of electrical components mounted on an electric vehicle;
A long plate-like metal member along the current path, and a plurality of bus bars for passing a current between the plurality of electrical components;
A cooling bar that has electrical conductivity and thermal conductivity and is a long plate-like member along a predetermined path;
A holding body having insulation and thermal conductivity, and holding the plurality of bus bars and the cooling bar in parallel at least in a part of the range;
A metal structure that houses or supports the plurality of electrical components;
With
The electric unit of the electric vehicle characterized in that at least one location of the cooling bar is thermally connected to the structure, and at least two locations separated from each other are connected to the structure in a conductive or alternating manner.   The electric unit of the electric vehicle according to claim 1, wherein both ends of the cooling bar are connected to the structure, and the cooling bar and a part of the structure form an electric closed circuit. The plurality of bus bars are configured to pass current between two electrical components,
The said holding body arrange | positions and hold | maintains these several bus bars and the said cooling bar in this order, and arrange | positions the said cooling bar to the said structure body side of these several bus bars. The electric unit of the electric vehicle as described. The plurality of bus bars include a first system bus bar that allows a current to flow between two electric components of a first set among three or more electric components, and the first set of three or more electric components. And a second system of bus bars that conduct current between two different sets of two electrical components,
The electric unit of the electric vehicle according to claim 1, wherein the holding body holds the first system bus bar, the cooling bar, and the second system bus bar in this order. The holder is made of a material having a thermal conductivity higher than that of air,
The electric unit of the electric vehicle according to any one of claims 1 to 4, wherein the plurality of bus bars and the cooling bar are embedded in the holding body.

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