The application scenarios of new energy cables mainly include the interior line of the vehicle, the charging gun/charging pile and the on-board charging. The high-voltage wiring harness in the car is mainly used to provide high-voltage and strong electric power supply for the new energy vehicles. It is a high-safety part in the new energy vehicles with the characteristics of large voltage/current, large wire diameter and a large number of conductors. This also makes the design of high voltage wiring harnesses in new energy vehicles face a lot of challenges.

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

1. High voltage/current

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

2. Large diameter wires are abundant

New energy vehicles in high voltage battery, inverter, transformer, low voltage battery, air conditioning compressor and other parts need to use large diameter wire, the number is very large.

2. Challenges faced by high-voltage wiring harnesses in cars

Due to the characteristics of high voltage/current and large wire diameter, the design of wiring harness is faced with challenges such as safety, wiring, shielding, weight and cost. In the face of these challenges, we summarize some countermeasures.

Step 1 Be safe

In the face of safety challenges, the selection of the interior wire, sealing and other aspects need to make some countermeasures

(1) Wire selection

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

Adopt wall thickness high line, wall thickness 0.6mm -- 1.1mm;

Heat resistant wire, heat resistant 150 degrees or above

Optional silicone rubber wire, crosslinked polyethylene/crosslinked polyolefin material

(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 conductor is required to have good roundness, dimensional stability and aging performance.

Step 2: Wiring

The interior high voltage wiring harness layout 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 a fixed point is not more than 100mm, and the distance between adjacent fixed points is generally not more than 150~200mm;

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

(6) Wire selection toughness wire such as silicone rubber wire, flexible crosslinked polyolefin wire.

Step 3 Mask

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 whole high voltage system is fully covered by a shielding layer. Then the high voltage wiring harness shielding electromagnetic interference measures are:

(1) Select shielded wire

The ultra-high current and voltage of electric vehicles will produce a great electromagnetic induction phenomenon when running. If the electromagnetic shielding problem is not well solved, it will certainly affect the performance of automotive electronic equipment. Therefore, the shielding wire is a good choice for the electromagnetic shielding wire of electric vehicles.

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

(2)Bundle Shielding

For the overall shield, wire is not shielded, currently mostly used by Japanese OEM.

Bundle Shielding is the process of protecting the wire bundle from electromagnetic interference with a lightweight braided metal shielding being used as a shielding component.

(3) aluminum tube shielding

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

Step 4: Weight

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

Step 5: Cost

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

Step 6 Go green

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