The importance of wiring harness arrangement for electric vehicles

With the rapid development of new energy vehicles and the continuous increase of market share, users' requirements for the safety, reliability and environmental protection of electric vehicles continue to improve, and the number of new energy electrical devices on vehicles has increased significantly. At the same time, with the emergence of new lines such as high-speed video data transmission, how to more effectively and reasonably arrange a large number of different types of wire harnesses in the limited car space, It has become a difficult problem for automobile product development.

Compared with fuel vehicles, electric vehicles have both similarities and differences in wiring harness arrangement. In short, the wiring harness layout of electric vehicles pays more attention than that of fuel vehicles.

Due to the special requirements of electric vehicles for protection level, EMC and ultra-high energy consumption, the development trend of electric vehicle wiring harness layout is mainly towards waterproof layout, highly integrated and lightweight.

1. Vehicle unified planning path

2. The paths on both sides are evenly arranged

3. The component system is highly integrated to simplify the harness layout

4. The fixing method reaches IP69K protection level

5. Mainline through-type integrated layout

6. Composite technology of power bus and power line communication

Development trend of electrical layout of automobile harness

From the distributed power technology in the electrical box to the new power bus technology, the new stage of low-voltage power supply and communication composite transmission control management has been realized, and the current wiring harness layout principle has been completely overturned, thus bringing a new change in wiring harness layout.

Power bus parallel distribution technology - power bus series distribution technology - power bus and power line communication composite technology.

Basic principles of wiring harness layout for electric vehicles

Harness layout architecture

The layout of automobile wiring harness generally includes H type, Y type, E type and Sichuan type. Generally speaking, if the high and low voltage harnesses are planned together, the Chuan-type arrangement is preferred, that is, the high voltage harnesses are in the middle and the low voltage harnesses are distributed on both sides, thus avoiding the EMC problem caused by the high and low voltage harnesses.

Vibration shock

The vibration and impact conditions of electric vehicle powertrain, layout space, NVH and other aspects are not good, so the harness arranged on the vibration source or powertrain must add a fixed point on the vibration body, and the clearance between the motion envelope of the harness and other components must be at least 25mm.

The harness shall withstand the impact and vibration caused by the instantaneous maximum displacement and rotation angle of the powertrain; In terms of arrangement, consider keeping enough distance from the power system.

Waterproof and airtight - vehicle harness

Electric vehicles are the most sensitive to water, and the requirements for wading traffic are also the most stringent. Generally speaking, the outdoor harness connector part under the plane formed by the left and right longitudinal beams needs to reach IP69k. The waterproof requirements can be met by adding necessary protective plates for shielding or improving the layout position of the connector.

Waterproof and airtight - power battery harness

All power battery packs are automobile grade plug-ins, which should be installed at the rear or upper part of the battery pack, and led from the indoor or rear to achieve reliable waterproof performance and convenient assembly and maintenance.

Waterproof and airtight - indoor harness

The indoor harnesses of fuel vehicles are basically fixed with holes. In order to completely solve the problem of water ingress into the fixing holes of harnesses, all indoor harnesses of electric vehicles are fixed with straight welding bolts. Of course, for some hollow sheet metal in the room, the hole fixing method can still be used.

electromagnetic interference

Compared with fuel vehicles, the electromagnetic interference of electric vehicles is more intense. In addition to reducing the interference sources and improving the anti-interference ability, the reasonable arrangement of the conductive path of the electrical components and wiring harness with electromagnetic interference and interference is also an important method to solve the electromagnetic interference problem.

Take the large screen display of the central control of the car reversing with the air conditioner as an example, the main reasons are not only the electrical components themselves, but also the wiring harness selection and wiring harness layout. After the shares, power lines and video signal lines in the harness are overlapped and separated, the image effect is significantly improved. In addition, the arrangement of grounding points is also an important reason for EMI.

Temperature field factor

Compared with fuel vehicles, electric vehicles have better temperature field environment. It can be seen from the test data that there are electric box, drive motor and PEU at the high temperature point in the front cabin. Since the maximum temperature point is not more than 60 ℃, as long as the cooling system is reasonably designed, the wiring harness layout in the front cabin cannot take too much consideration of the temperature field.

New substrate wire technology changes harness layout

The development and carrying of new substrate wire technology such as optical fiber can optimize and change the harness layout at the same time, which is an important development direction for the lightweight of the vehicle harness system.