The application scenarios of energy cables are mainly car interior, charging gun/charging pile and car charging, and the high-voltage wiring harness in the car is mainly to provide high-voltage and strong electric power supply for new energy vehicles, which is a high safety part in new energy vehicles, with large voltage/large current, large diameter wire number and other characteristics. This also makes the design of high-voltage wiring harnesses in new energy vehicles face a lot of challenges. Today, we will understand the wiring harness design and wire requirements of new energy vehicles.

Figure A typical example of a high-voltage wiring harness for a pure electric vehicle

First, the basic characteristics of high-voltage wiring harness in the car

1. High voltage/high current

The battery voltage of new energy vehicles can reach 600V, and the corresponding wire voltage level can reach 300A. The traditional fuel vehicle battery voltage is generally 12V, and the corresponding wire voltage level is less than 60V.

2. The number of large diameter conductors is large

New energy vehicles need to use large diameter wires in high-voltage batteries, inverters, transformers, low-voltage batteries, air conditioning compressors and so on, and the number is very large.

Second, the challenges faced by high-voltage wiring harnesses in the car

Due to the characteristics of high voltage/high current and large number of wire diameters, the design of wire harnesses faces challenges such as safety, wiring, shielding, weight and cost. In the face of these challenges, we have summarized some countermeasures.

1 . Be safe

In the face of safety challenges, some countermeasures need to be taken in terms of wire selection and sealing in the car

(1) Wire selection

High voltage conductor 600V/900V (AC) (reference ISO19642);

The wall thickness line is adopted, and the wall thickness is 0.6mm-1.1mm;

Heat resistant wire, heat resistant 150 degrees or above

Optional silicone rubber wire, crosslinked polyethylene/crosslinked polyolefin material

Diagram wire outer protection

(2) Seal

It matches with the high pressure connector and is sealed in a variety of ways such as wire seals, heat shrink tubes, Pass-thru seals, and rubber parts for water and dust protection (IP67, IP69K). The wire is required to have good roundness, dimensional stability and aging performance.

Diagram connection seal

2. Wiring

The high-voltage wiring harness layout in the car has the following requirements:

(1) Under static load, the minimum turning radius is 4 times the outer diameter of the conductor;

(2) Under dynamic load, the minimum turning radius is 8 times the outer diameter of the conductor;

(3) The minimum distance between high and low voltage wires is not less than 100mm;

(4) The distance between the outlet end of the high voltage connector and the first fixed point is not more than 100mm, and the distance between the adjacent fixed points is generally not more than 150~200mm;

(5) The high-voltage wiring harness is arranged under the car as far as possible;

(6) Wire selection of ductile wire such as silicone rubber wire, flexible cross-linked polyolefin wire.

3. Block

Because of the electromagnetic field interference caused by high voltage and large AC of new energy vehicles, as well as the electromagnetic interference caused by the rapid on-off of electrical components, taking into account the electromagnetic interference factors, the entire high voltage system is fully covered by the shielding layer. Then the measures of high voltage wiring harness shielding electromagnetic interference are:

(1) Select shielded wire

The ultra-high current and voltage of electric vehicles will produce a large electromagnetic induction phenomenon when running, if the electromagnetic shielding problem is not well solved, it will inevitably affect the performance of automotive electronic equipment, so the selection of shielding wire as a high-voltage wire for electric vehicles is a good choice for electromagnetic shielding.

The shield wire is braided by multiple strands of tinned annealed copper wire. The thin copper wire can maintain the flexibility of the design and has a coverage rate of more than 90%. Reasonable insulation and sheath stripping force should be controlled to meet the requirements of wire stripping processing.

(2)Bundle Shielding

For the overall shielding, the wire is not shielded, and is currently used by Japanese Oems.

Bundle Shielding is the protection of wire bundles from electromagnetic interference when a light braided metal shielding is used as a shielding component.

Figure Bundle Shielding example

(3) Aluminum tube shielding

Aluminum tube shielding also belongs to the overall shielding, the wire is not shielded, and it is currently used by Japanese and American Oems.

Figure aluminum tube shielding example

4. Weight

For new energy vehicles, lightweight is very important for the improvement of driving range. Then the weight of the wire harness can be started on the material selection, and the conductor material can be a new conductor conductor, such as a new aluminum conductor; The insulation material can be selected with low density material and thin wall processing.

5. Cost

At present, the high-voltage wire in the car is mainly imported, the wire threshold is high, the output of the mass production model in the early stage is less, and the new energy vehicles are facing greater cost pressure, and more domestic resources need to be developed.

6. Environment

The high-voltage wiring harness in the car needs to use low-volatile, low-VOC, low-odor materials.