With the rise of new energy vehicles and automotive intelligent network connection, the working environment of automotive wiring harnesses has changed from "low voltage" to "high voltage and large current". The transformation of working environment has put forward higher requirements for the transmission capacity, mechanical strength, insulation protection, electromagnetic compatibility and anti-interference, body weight and other aspects of automotive wiring harnesses. This also causes the production process requirements and quality requirements of automotive wiring harnesses to change accordingly. The main difference between the new energy vehicle wiring harness and the traditional fuel vehicle wiring harness is the high voltage wiring harness. High voltage wire harness is not only a key part of the high voltage electrical system of new energy vehicles, but also an important guarantee for the safe and reliable operation of new energy vehicles.
Design of high voltage wire harness 1.1 Composition of high voltage harness High voltage wiring harness mainly includes: high voltage connector, high voltage cable, ground terminal and tie, outsourcing material, tape, heat shrink casing, rubber sleeve, installation support and other auxiliary materials. 1.2 High Voltage connector According to the function definition, it can be divided into two kinds: small current and large current. The large current is mainly used in OBC, motor, battery and other power systems, while the small current is mainly used in compressor, PTC, battery heating device and DCDC and other functional appliances. 1.3 High voltage cable High voltage cables are mainly divided into shielded and unshielded cables（bellow） with diameters ranging from 2.5mm² to 120mm². Shielded cable: Unshielded cable:
1.4 Auxiliary accessories The auxiliary accessories are not very different from those used in the traditional low voltage harness, but the outsourced materials need to be covered with red or orange, so as to play the role of high voltage danger warning.
Technical requirements for cables 2.1 Structure High voltage cable is mainly composed of wire core and insulation material, shielding wire also has shielding layer and double insulation structure. The wire core is made of a certain number of single wires first bunched and then concentrically retwisted to form the soft conductor required by the high voltage cable. According to the structure can be divided into shielded wire and non-shielded wire, according to the use can be divided into single core shielded wire and multi-core shielded wire (below).
Multi-core shielded wire: 2.2 Insulation Materials Insulation materials mainly include wire core insulation and sheath insulation. The choice of wire core insulation material is mainly to consider the heat resistance requirements and mechanical strength and softness, sheath material according to the thermal and mechanical requirements. Sheath insulation due to direct contact with the environment, liquid resistance and wear resistance and other environmental properties of the sheath requirements are particularly important. At present, cross-linked polyethylene and silicone rubber are mainly used as the basic materials of insulation layer. 2.3 Shielding Due to the requirements of EMC(electromagnetic compatibility), multiple copper wires are used to form a braided shielding. Tinned copper wire makes it stronger against environmental influences such as oxidation. The use of thin copper wire can maintain the flexibility of the design, woven shielding can be combined with other kinds of shielding, such as aluminum plastic conforming film. The shield can be wrapped with a layer of non-woven fabric to ensure easy stripping of the sheath during assembly. 2.4 Bending Radius Due to the limitation of space, the path through the cable is very narrow and complex, and the cross-sectional area is larger than that of the ordinary wire harness, so the required bending radius is also large, and the high bending force is difficult to overcome. In order to solve this problem, high flexibility of high voltage cable is crucial, only flexible design, through the vehicle routing can be easily realized. Usually 5~10 times the recommended SR wire diameter of the cable.
At present, China's new energy vehicles have just started, the new energy products in the market are mixed, and the standards are not perfect. However, with its rapid development, there will be many newer technologies and products in the market in the future. With the support of national policies, the whole electric vehicle market in China will enter the track of more rapid development and standardization in the future. By convenient service. In the development of management system, we should also use advanced development technology to ensure the effect of framework development and make the management advantage of management system more significant.
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