JP2010061954A - Power cable for vehicle, and vehicle drive device - Google Patents

Abstract

The present invention provides a vehicular power cable that suppresses an increase in the size of both an inverter side and a motor side while maintaining an electromagnetic wave noise shielding effect by a shield layer.
A cable 24u for electrically connecting an inverter 14 and a motor 16 to supply AC power converted from DC power by an inverter 14 installed in the vehicle body 4 to a motor 16 installed in the vehicle body 4. , 24v, 24w, and a conductive shield layer 32 that extends along the longitudinal direction of the cable, covers the periphery of the cable, and is grounded to the vehicle body 4 at both ends. The shield layer 32 is divided in the middle of the longitudinal direction, and the shield layer divided both ends 36 a and 36 b in the divided portion 36 are connected via the impedance means 38.
[Selection] Figure 2

Description

  The present invention relates to a vehicle power cable and a vehicle drive device using the same, and more particularly to a vehicle power cable having a shield layer that shields electromagnetic waves radiated from the cable and a vehicle drive device using the same.

  Conventionally, an electric vehicle having an AC motor as a driving power source is known. In such an electric vehicle, generally, DC power supplied from a battery is converted into AC power by an inverter and then input to an AC motor, whereby the AC motor is rotationally driven to obtain driving power. .

  As a technique applicable to the electric vehicle, Patent Document 1 discloses a vehicle power electronics system that suppresses propagation of high-frequency potential fluctuations to a vehicle body. In this vehicle power electronics system, electric power converted from direct current to alternating current by an inverter is supplied to a motor through three shield wires. The inverter and the motor are individually stored in metal casings, and each casing is grounded to the vehicle body via a ground wire. Each shield wire passes through a through hole provided in each housing in a state where it is electrically insulated from the housing by an insulating material. Both ends of the core wire of the shield wire are connected to each phase terminal of the inverter and the motor. The shield layer at the end of the shield wire introduced into the housing is electrically connected to the housing for storing the inverter via a high frequency reactor as high frequency transmission suppressing means. According to this configuration, the high frequency generated in the core wire due to switching of the inverter induces a high-frequency potential fluctuation in the shield layer, but is absorbed by the high-frequency reactor, so that it can be suppressed from propagating to the vehicle body through the ground wire. ing.

JP 2006-80215 A

  However, in the vehicle power electronics system of Patent Document 1 described above, the system is employed to connect the end of the shield layer to a metal casing via a high frequency reactor provided separately from the shield layer. There is a possibility that the configuration on the inverter circuit side will be enlarged. In particular, in an electric vehicle, a hybrid vehicle including an engine as a power source for driving or a generator motor in addition to a motor has a smaller installation space allowed for mounting the engine and the motor on the vehicle. For this reason, it is not desirable to increase the size of the configuration on the inverter circuit side by arranging the high frequency reactor as described above.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicular power cable that suppresses an increase in the size of both the inverter side and the motor side while maintaining the electromagnetic wave noise shielding effect by the shield layer, and a vehicular drive device using the same Is to provide.

  The vehicle power cable according to the present invention electrically connects the voltage converter and the motor to supply the AC power converted from the DC power by the voltage converter installed in the vehicle body to the motor installed in the vehicle body. A power cable for a vehicle including a cable to be connected and a conductive shield layer that extends along the longitudinal direction of the cable and covers the periphery of the cable and is grounded to the vehicle body at both ends, The shield layer is divided in the middle of the longitudinal direction, and both end portions of the shield layer in the divided portion are connected through impedance means.

In the vehicular power cable according to the present invention, both divided end portions of the shield layer dividing portion have overlapping portions arranged to overlap each other in the radial direction of the cable, and the impedance means overlaps the dividing end portions. It may be inserted in between.
Here, the “impedance means” includes an insulating member having an infinite electric resistance or impedance.

  Further, in the vehicle power cable according to the present invention, the impedance means may be constituted by a coil formed by winding an electric conducting wire, and the coil may connect between both divided ends of the shield layer.

  Further, in the vehicle power cable according to the present invention, the cables may have a number corresponding to the number of phases of the AC power, and the shield layer may cover the cables for all the phases.

  Furthermore, a vehicle drive device according to the present invention includes any one of the vehicle power cables according to the present invention, a power conversion device and a travel motor that are electrically connected by the vehicle cable, and the power conversion device. And a power storage device for supplying DC power to the battery.

  According to the vehicle power cable and the vehicle drive device according to the present invention, the shield layer covering the periphery of the cable along the longitudinal direction is divided in the middle of the longitudinal direction, and both ends of the shield layer division in the divided portion are impedances. By being connected via the means, it is possible to suppress an increase in size when an impedance member such as a high frequency reactor is provided on the inverter side or the motor side separately from the shielded cable.

  Moreover, the shielding effect with respect to the high frequency electromagnetic wave noise radiated | emitted from a cable is not deteriorated by setting it as the structure by which the both ends of a division | segmentation in the division part of a shield layer overlap and are arrange | positioned regarding the radiation | emission direction of the said cable.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. In this description, specific shapes, materials, numerical values, directions, and the like are examples for facilitating the understanding of the present invention, and can be appropriately changed according to the application, purpose, specification, and the like.

  FIG. 1 shows a schematic configuration of a vehicle drive device 1 using a vehicle power cable 10 according to an embodiment of the present invention. The vehicle drive device 1 includes a battery 12 as a power storage device, an inverter 14 as a voltage conversion device, a motor 16 as a driving power output source, and vehicle power that electrically connects the inverter 14 and the motor 16. Cable (hereinafter simply referred to as “power cable”) 10.

  The vehicle drive device 1 may be applied to an electric vehicle having only the motor 16 as a driving power source, or a motor that outputs power for driving or a generator motor using gasoline or light oil as a fuel. It may be applied to a hybrid vehicle having 16 together.

  The battery 12 includes a lithium ion secondary battery or a nickel hydride secondary battery that can charge and discharge electric power. However, the power storage device may be configured by a capacitor that can be charged and discharged without a chemical reaction.

  The battery 12 is electrically connected to the inverter 14 via the positive electrode bus 18 and the negative electrode bus 20. A smoothing capacitor 22 is electrically connected between the positive electrode bus 18 and the negative electrode bus 20. As a result, the DC power output from the battery 12 is supplied to the inverter 14 via the smoothing capacitor 22.

  The inverter 14 has a function of converting DC power supplied from the battery 12 into AC power, and includes a plurality of switching elements (for example, IGBTs) as is well known. In the inverter 14, a switching signal is received from a control unit (not shown) and the switching element is controlled to be turned on / off, thereby performing a DC / AC conversion function.

  A permanent magnet type three-phase AC motor is preferably used for the motor 16. The power cable 10 includes three cables 24u, 24v, 24w for each phase of U phase, V phase, and W phase, and both ends of each cable 24u, 24v, 24w are both the inverter 14 and the motor 16. Are connected to each phase terminal. Thereby, the alternating voltage output from the inverter 14 is applied or input to the motor 16 via the power cable 10.

  FIG. 2 shows a cross section of the power cable 10 cut along the longitudinal direction, and the cables 24u, 24v, and 24w are shown in a side view. Each cable 24u, 24v, 24w has a core wire 26 made of, for example, copper wire extending through the center thereof, an insulating layer 28 made of, for example, resin covering the periphery of the core wire 26, and a core wire 26 at both ends of the cable. And a metal attachment portion 30 which is connected to each output terminal portion of the inverter 14 and the input terminal portion of the motor 16 by a method such as screwing or insertion. The attachment portion 30 and the vicinity thereof are shielded by being covered with a metal connector case (not shown).

  The power cable 10 includes a conductive shield layer 32 that extends along the longitudinal direction and covers the periphery of the three cables 24u, 24v, and 24w. In FIG. 2, the shield layer 32 is illustrated by cross-hatching. The shield layer 32 is composed of, for example, a net assembly formed by knitting aluminum wires or a sheet-like metal layer. Further, in the power cable 10, for example, a resin protective member 34 is provided on the outer periphery of the shield layer 32.

  The shield layer 32 is grounded to the conductive vehicle body 4 via ground wires 2 and 3 at both ends in the longitudinal direction. Further, the shield layer 32 has a divided portion 36 divided in the middle of the longitudinal direction. The split end portions 36a and 36b of the shield layer 32 in the split portion 36 are arranged so as to overlap each other with respect to the radial direction of the cables 24u, 24v and 24w, and the split end portions 36a and 36b in the overlap portion 37 are in between. For example, an insulating member (impedance means) 38 formed in a cylindrical shape is connected to each other. In FIG. 2, the insulating member 38 is illustrated by stippling.

Next, the operation and action of the vehicle drive device 1 including the power cable 10 having the above configuration will be described with reference to FIGS. 3 schematically shows a coil array of first to eighth coils 41-48 constituting the U-phase coil 40 in the motor 16, and FIG. 4 shows the U-phase to V-phase voltage and the U-phase coil 40. FIG. 5 is a graph showing a measurement result of the voltage between the first coil 41 and the second coil 42 in relation to time, and FIG. 5 is a flow of common mode current in a vehicle drive device using a power cable including a shield layer having no dividing portion FIG. 6 is a graph showing a result of voltage measurement applied to the first to eighth coils 41-48 of the U-phase coil 40, and FIG. 7 is a common diagram in the vehicle drive device 1 of the present embodiment. It is a figure similar to FIG. 5 which shows the flow of a mode current.

  As shown in FIG. 3, the U-phase coil 40 in the motor 16 includes first to eighth coils 41 to 48 that are arranged along the circumferential direction inside a cylindrical stator core (not shown) and connected in series. The end 41a of the conducting wire constituting the first coil 41 is electrically connected to the mounting portion 30 of the U-phase cable 24u via the input terminal portion of the motor 16, while the conducting wire constituting the eighth coil. Is connected to the neutral point of the motor 16. Other V-phase coils and W-phase coils are configured in the same manner.

  When DC power from the battery 12, that is, DC voltage is converted into AC voltage by switching in the inverter 14 and applied to the motor 16, as shown in FIG. 4, the voltage between each phase coil, for example, U-phase coil − It has been found from the measurement results that the voltage between the V-phase coils greatly pulsates and then gradually converges to a desired voltage value. It has been found that such a large pulsation or fluctuation of the interphase voltage is caused by a high-frequency common mode current flowing between the inverter 14 and the motor 16 via the vehicle body 4 or the shield layer of the power cable.

  In FIG. 5, a state in which the common mode current circulates through the U-phase coil 40 is indicated by a thick line. At the rise of the U-phase to V-phase coil voltage when the AC voltage is applied to the motor 16 (the same applies to the V-phase to W-phase and W-phase to U-phase), the high-frequency common mode current Ic is applied to the U-phase coil 40. → Stray capacitance 50 existing between U-phase coil 40 and stator core 17 → Stator core 17 → Motor case (not shown) → Shield layer without car body 4 and dividing portion 36 → Inverter grounding capacitor (or common mode capacitor) 15 → Inverter 14 → Cable 24u → U phase coil 40 It flows instantaneously (for example, less than 1 nanosecond).

  When such a common mode current flows through the U-phase coil 40 of the motor 16, the voltage sharing ratios of the first to eighth coils 41-48 constituting the U-phase coil 40 are as shown in FIG. , Second coils 42,..., And the potential difference between the first coil 41 and the second coil 42 increases. For this reason, when the potential difference becomes larger than a certain threshold value, partial discharge may occur, and the insulation performance of the coil may be deteriorated.

  Here, in FIG. 4, the voltage between the first coil 41 and the second coil 42 of the U-phase coil 40 in the case where a power cable including a shield layer without a dividing portion is used is indicated by a solid line 52. In this case, the common mode current Ic flowing back from the motor 16 to the inverter 14 flows predominantly through the shield layer of the power cable, which is a path having a lower electrical resistance than the vehicle body 4.

  On the other hand, in the vehicle drive device 1 of this embodiment, as shown in FIG. 7, the dominant flow path of the common mode current Ic is cut by providing the dividing portion 36 in the shield layer 32 of the power cable 10. Therefore, the common mode current Ic can be reduced. As a result, as indicated by a solid line 54 in FIG. 4, the potential difference between the first coil 41 and the second coil 42 of the U-phase coil (the same applies to the V-phase and W-phase coils) 40 can be reduced, and the motor 16 The insulation performance of each phase coil can be improved.

  Further, by providing a dividing portion 36 in which electrical conduction is interrupted by the insulating member 38 in the middle of the shield layer 32 in the longitudinal direction of the power cable 10, an impedance member such as a high frequency reactor is connected to the power cable 10. The enlargement of the structure in the case where it is separately provided on the inverter 14 side or the motor 16 side can be suppressed.

  Further, since the divided both end portions 36a and 36b of the divided portion 36 of the shield layer 32 have an overlapping portion 37 arranged so as to overlap with each other in the radiation direction of the cables 24u, 24v and 24w, high frequencies radiated from the cables 24u, 24v and 24w. The shielding effect against electromagnetic wave noise is not deteriorated.

  Then, the modification regarding the said power cable 10 is demonstrated.

  In the above description, the insulating member 38 is inserted between the divided end portions 36a and 36b of the shield layer 32 to form the divided portion 36. However, instead of the insulating member 38, a thin film made of a dielectric material is formed at the divided end portions 36a and 36b. The dividing portion 36 may be configured as a capacitor (impedance means) by being sandwiched. In this case, the capacitance C of the capacitor is set to 1 nF or less, for example. As a result, a high-frequency common mode current Ic of, for example, several M to 20 MHz flowing through the shield layer 32 via the dividing portion 36 can be attenuated by the impedance of the capacitor, thereby reducing the common mode current Ic. Similar effects can be obtained.

  Further, as shown in FIG. 8 which is a partial enlarged cross-sectional view of the power cable 10, instead of interposing an insulator or a dielectric in the dividing portion 36 of the shield layer 32, the dividing end portions 36 a and 36 b of the shield layer 32 are not interposed. The dividing portion 36 may be configured by performing an oxidation treatment for increasing the resistance (the oxidation treatment range is shown by a one-dot chain line portion) and connecting or connecting directly. An example of the oxidation treatment here is alumite treatment when the shield layer 32 is formed of a braided aluminum wire. Thereby, the common mode current Ic flowing through the shield layer 32 is reduced by the dividing portion 36 having a high resistance value, and the same effect as described above can be obtained. In this modification, the divided both ends 36a and 36b of the shield layer 32 subjected to the oxidation treatment themselves constitute impedance means.

  Further, as shown in FIG. 9 which is a partial enlarged cross-sectional view of the power cable 10, a predetermined distance is provided between the divided ends 36a and 36b of the shield layer 32, and a coil ( Impedance means) 60 may be inserted to connect or connect the divided ends 36a, 36b. Here, the inductance L of the coil 60 is set to 0.01 mH or more, for example. In this modification, the divided end portions 36a and 36b of the shield layer 32 do not have overlapping portions, and therefore the coil 60 is wound tightly without gaps or electromagnetic waves radiated from the cables 24u, 24v and 24w. Only a gap that does not leak noise to the outside is allowed, and the shielding effect of the shield layer 32 is not deteriorated. As described above, even in the modification in which the divided end portions 36 a and 36 b are connected by the coil 60, a high-frequency common mode current Ic of, for example, several M to 20 MHz flowing through the shield layer 32 via the coil 60 is attenuated by the impedance of the coil 60. Thus, the common mode current Ic can be reduced, and as a result, the same effect as described above can be obtained.

It is a schematic block diagram of the vehicle drive device using the electric power cable which is one Embodiment of this invention. It is sectional drawing along the longitudinal direction of an electric power cable. It is a figure which shows roughly the coil row | line | column of the 1st-8th coil which comprises the U-phase coil in a motor. It is a graph which shows the measurement result of the voltage between U phase-V phase coils, and the voltage between the 1st coil in a U phase coil, and the 2nd coil in relation to time. It is the schematic which shows the flow of the common mode electric current in the drive device for vehicles using the electric power cable which does not have a parting part. It is a graph which shows the voltage measurement result shared and applied to the 1st-8th coil of a U-phase coil. FIG. 6 is a view similar to FIG. 5 showing a flow of common mode current in the vehicle drive device of FIG. 1. It is a figure which shows the modification regarding the parting part of the shield layer of an electric power cable. It is a figure which shows another modification regarding the division part of the shield layer of an electric power cable.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Vehicle drive device, 2, 3 Ground wire, 4 Car body, 10 Vehicle power cable, 12 Battery, 14 Inverter, 16 Motor, 17 Stator core, 18 Positive electrode bus, 20 Negative electrode bus, 22 Smoothing capacitor, 24u U phase cable, 24v V-phase cable, 24w W-phase cable, 26 core wire, 28 insulating layer, 30 mounting portion, 32 shield layer, 34 protective member, 36 dividing portion, 36a, 36b dividing both ends, 37 overlapping portion, 38 insulating member, 40 U Phase coil, 41-48 1st to 8th coil, 50 stray capacitance, Ic common mode current.

Claims (5)

A cable for electrically connecting the voltage converter and the motor to supply the AC power converted from the DC power by the voltage converter installed in the vehicle body to the motor installed in the vehicle body, and the longitudinal direction of the cable A power cable for a vehicle including a conductive shield layer that extends along the cable and covers the periphery of the cable and is grounded to the vehicle body at both ends,
The power cable for a vehicle according to claim 1, wherein the shield layer is divided in the middle of the longitudinal direction, and both ends of the shield layer in the divided part are connected through impedance means. The vehicle power cable according to claim 1,
The divided both ends of the divided portion of the shield layer have overlapping portions arranged so as to overlap with respect to the radial direction of the cable, and the impedance means is inserted between the overlapping portions of the divided end portions. Power cable for vehicles. The vehicle power cable according to claim 1,
The electric power cable for vehicles, wherein the impedance means is constituted by a coil formed by winding an electric conducting wire, and the coil connects between both divided ends of the shield layer. The vehicular power cable according to any one of claims 1 to 3,
The cable has a number corresponding to the number of phases of the AC power, and the shield layer comprehensively covers cables for all phases. A vehicle power cable according to any one of claims 1 to 4,
A power converter and a traveling motor electrically connected by the vehicle cable;
And a power storage device that supplies direct-current power to the power conversion device.

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