Abstract: As a core component of the power transmission system of new energy vehicles, high-voltage wiring harnesses and connectors have an important impact on vehicle performance and safety. The design principles of high voltage wiring harness for new energy vehicles, including strengthening wiring harness layout, material selection, manufacturing process, and analyzing the performance requirements and type characteristics of connector selection, can improve the power transmission efficiency of new energy vehicles.

introduction

As the medium of high-voltage power transmission, the high-voltage wiring harness connects various components on the high-voltage system, transmits electrical energy and shields external signal interference, and is the main carrier of power output of new energy vehicles. High voltage harness has the characteristics of high voltage, high current, high protection level and anti-electromagnetic interference, is the neural network of new energy vehicle high voltage system, is related to the vehicle performance and safety of the key components. Therefore, high-voltage wiring harnesses and connectors of new energy vehicles are key components of the power transmission system, and their design and selection affect vehicle performance and safety. In this paper, the selection of high-voltage wiring harnesses and connectors for new energy vehicles is deeply studied.

1. The necessity of high-voltage wiring harness design and connector selection for new energy vehicles

1.1 Basis for efficient power transmission

In new energy vehicles, batteries are the source of electricity, but battery energy storage is limited. Reducing the amount of power lost during transmission means more efficient use of limited battery power and longer vehicle range. To achieve this, high-voltage wiring harnesses need to use materials with excellent electrical conductivity, optimize the layout of the wire harnesses cross-sectional area, and reduce resistance and heat loss. In the driving of new energy vehicles, the power demand fluctuates with the change of driving conditions. The excellent high voltage harness design smoothly responds to fluctuations and ensures a continuous and stable supply of power to motors and other power consuming equipment.

1.2 Security performance guarantee

The high voltage harness has good insulation protection to prevent current leakage. The wire harness insulation material is strictly selected to ensure that it can withstand the long-term test of the working voltage of new energy vehicles (usually above 400 V). The harness voltage withstand design is the key to ensure that the harness will not fail due to high voltage in extreme cases, and maintain the safety of the vehicle and passengers.

1.3 System Reliability Improvement

Careful planning of the wiring harness path fixation mode can reduce the vibration friction of the wiring harness during the running of the vehicle and reduce the risk of damage to the wiring harness. Reasonable layout of wiring harnesses can ensure stable performance of wiring harnesses in complex environments and improve system reliability. The use of highly conductive and heat-resistant materials to make wiring harnesses can significantly extend the service life of wiring harnesses, resist harsh working environments, and reduce system failures caused by aging materials.

1.4 Promotion of technological progress

With the continuous development of new energy vehicle technology, the performance requirements for high-voltage wiring harnesses and connectors are becoming higher and higher. Research on high-voltage wiring harness design and connector selection can meet the current market demand, promote relevant technological innovation and progress, promote the overall development of the new energy vehicle industry, and form a virtuous cycle.

1.5 Consideration of cost optimization

In addition to performance safety, cost is an important factor that new energy vehicle manufacturers must consider. Through reasonable high-voltage wiring harness design and connector selection, cost optimization can be achieved under the premise of ensuring performance safety, which helps to improve product market competitiveness and provide strong support for the sustainable development of enterprises.

2 High-voltage wiring harness design for new energy vehicles

2.1 High-voltage wiring harness design scheme

(1) Design objectives. The design scheme meets the high efficiency and high safety requirements of high voltage wiring harnesses for new energy vehicles, optimizes the wiring harnesses layout, selects suitable materials and adopts advanced manufacturing processes to achieve lightweight and efficient transmission of high voltage wiring harnesses.

(2) Wiring harness layout design. According to the chassis structure of new energy vehicles, reasonably plan the path of high-voltage wiring harnesses, avoid too long or too short wiring harnesses, reduce the vibration friction of wiring harnesses during vehicle operation, adopt reliable fixing methods, use special wiring harnesses and brackets to ensure that the wiring harnesses will not shake off during vehicle driving, and improve the stability and safety of wiring harnesses. Protect the harness from damage by adding protective covers in areas where the harness is vulnerable to wear or external environment.

(3) Material selection. Select wire materials with high conductivity, heat resistance and corrosion resistance, such as high temperature superconducting materials or special alloy wires, to ensure that the wires can maintain stable performance in harsh environments such as high temperature and high humidity. High performance insulating materials, such as polyimide (PI) or polytetrafluoroethylene (PTFE), provide good electrical insulation properties. The connector is made of high-strength, high-conductivity metal materials, such as copper alloy or stainless steel, to ensure that the connector will not have poor contact problems during long-term use.

(4) Manufacturing process. Automated production lines are used for high-voltage wiring harness manufacturing to improve production efficiency and ensure product quality. Use precision crimping equipment to ensure a reliable connection between wires and connectors and reduce contact resistance temperature rise. Strict quality testing is carried out in production, including wire resistance testing, connector insertion and withdrawal force testing, etc., to ensure that the performance of the high voltage wiring harness meets the design requirements.

(5) Safety protection design. Overcurrent protection devices, such as fuses or circuit breakers, are installed in the high-voltage wire harnesses to prevent damage to the wire harnesses due to excessive current. Ensure that the high-voltage wire harness is effectively isolated from the low-voltage wire harness and control wire harness to avoid electromagnetic interference and potential security risks. Reasonably design the grounding system to ensure reliable grounding of high-voltage wiring harnesses and reduce the risk of electromagnetic interference and static accumulation.

2.2 High-voltage wiring harness layout design

High voltage wiring harness layout design should follow several basic principles, namely safety, reliability, economy and maintainability. Keep the wiring harness away from heat sources and moving parts to prevent damage and fire. Reliability requires that the wiring harness is stable and not affected by environmental factors such as vibration, temperature, and humidity. Economy needs to meet the performance requirements of the premise, as far as possible to reduce the length of wire harness and material consumption, reduce costs. Maintainability requires that the wiring harness is neatly arranged, clearly marked, and easy to repair and replace.

2.3 Materials and manufacturing process of high voltage wiring harness

2.3.1 Material selection

(1) Wire material. High-voltage wiring harnesses of new energy vehicles mainly use high-purity copper or aluminum as wire materials, which have good conductive properties to meet the needs of high-current and high-voltage transmission. For example, copper conductors are widely used because of their excellent electrical conductivity and mechanical strength, and aluminum conductors have advantages in some applications because of their light weight and low cost. To ensure the safety of the high voltage harness, the conductor is covered with insulation material. Common insulating materials include cross-linked polyethylene (XLPE), polyvinyl chloride (PVC), ethylene-propylene rubber (EPR), etc. XLPE is favored in new energy vehicles because of its excellent electrical properties and heat resistance.

(2) Shielding material. In order to prevent the impact of electromagnetic interference (EMI) on other electronic systems of the vehicle, high-voltage wiring harnesses use shielding materials to effectively absorb electromagnetic waves and reduce interference, common shielding materials include metal braided mesh, aluminum foil, conductive cloth, etc.

(3) Sheath material.

The sheath is an important part of protecting the high pressure wire harness from the external environment, which needs to have the characteristics of weather resistance, wear resistance, oil resistance and flame retardant, etc. Common sheath materials include polyvinyl chloride (PVC), thermoplastic elastomer (TPE), nylon and so on.

2.3.2 Manufacturing process

Wire manufacturing includes wire drawing, annealing, twisting and other processes, the raw material metal through the wire drawing machine to make the required diameter of the monofilament; Annealing treatment to improve wire flexibility. Several monofilaments are twisted into one strand to enhance the mechanical strength of the wire. Insulation treatment is the process of coating the external wire with insulating material. The insulating material is uniformly coated on the surface of the wire through the extruder, and the solid insulation layer is formed after cooling and solidification. Shielding manufacturing involves wrapping shielding materials such as metal braided mesh or aluminum foil tightly around the outside of the insulation layer, a process that requires tight contact between the shielding layer and the wire to effectively reduce electromagnetic interference. The high voltage harness is equipped with connectors at both ends for connection to other electrical systems in the vehicle. Connector manufacturing requires precision machining and injection molding techniques to ensure connector accuracy. During the assembly process, it should be ensured that the wire is in close contact with the connector to reduce the contact resistance and improve the electrical conductivity.

3 Research on connector selection

3.1 Performance requirements of connectors

(1) Electrical performance requirements. The rated voltage of the connector should meet the voltage requirements of new energy vehicles, considering the high voltage system of new energy vehicles, the rated voltage of the connector should be above 200 V to ensure safe and stable operation in a high voltage environment. Insulation resistance is an important indicator to measure the electrical performance of the connector, to ensure that the connector does not leak or short circuit in a high voltage environment, its insulation resistance should meet the relevant standards, such as the requirement of 100 MΩ. The voltage resistance of the connector should be above 1 000 V to ensure the safe work in the high pressure system of new energy vehicles.

(2) Mechanical performance requirements. The insertion and withdrawal force of the connector is an important indicator to measure its ease of use. In order to facilitate operation and not be too loose during insertion and withdrawal, the insertion and withdrawal force is required to be within the specified range, usually not greater than 100 N. The mechanical life of the connector refers to the number of times it can be inserted and removed normally, and it can maintain stability and reliability in long-term use. The mechanical life of the connector is generally required to be inserted and removed more than 50 times. Because the new energy vehicle will generate vibration during driving, the connector should have good anti-vibration performance, and the electrical and mechanical properties of the connector should not be affected at the specified frequency amplitude.

(3) Temperature adaptability requirements. Connectors work normally in a wide temperature range. The temperature adaptability must be in the range of -40 ° C to 125 ° C. The electrical and mechanical properties of connectors are not affected, as shown in Table 1.

(4) corrosion resistance requirements. The choice of connector material is related to its corrosion resistance. The shell is preferred to have excellent corrosion resistance metal materials, such as aluminum or zinc alloy, and the surface can be sandblasted. The contact part is copper, gold plating, silver plating, nickel plating and other processes are used to improve its electrical conductivity under the premise of meeting the corrosion protection. Connectors should have good sealing performance to prevent the intrusion of harmful substances such as moisture and dust and effectively avoid corrosion. The sealing structure is designed to ensure that the sealing effect is maintained in a variety of harsh environments. A layer of anti-corrosion coating can be coated on the surface of the connector to enhance its anti-corrosion performance and ensure that the connector is tightly inserted and not easy to loose. Special sealing can be used to ensure that the joint is protected from moisture and corrosive substances. Regular maintenance inspection of the plug-in is an important measure to ensure its long-term anti-corrosion performance.

3.2 Types and features of connectors

3.2.1 Main Types of Connectors

(1) LV standard plug-in. LV standard plug-in has the largest liquidity in the domestic market, and the process standards are relatively perfect. Suitable for a variety of electrical connection needs, with good versatility, widely used in new energy vehicle battery packs, motor controllers and other key components connection.

(2) USCAR standard plug-in. The USCAR standard plug-in is an international standard connector with high compatibility reliability. Its design meets the strict requirements of the automotive industry to ensure stable work in harsh environments, and is mainly used in international brand new energy vehicles to meet the global market demand.

(3) Daily standard plug-in. The Japanese standard plug-in is designed according to Japanese standards, focusing on refinement and high performance. This type of connector has a small volume and excellent electrical performance.

3.2.3 General features of connectors

Due to the high voltage system requirements of new energy vehicles, connectors must withstand the impact of high voltage and high current to ensure the stability of power transmission. Connector design needs to pay attention to the selection of insulation materials to prevent leakage and short circuit. In high temperature environment, the connector maintains stable electrical performance, and does not affect its normal operation due to temperature rise. The connector design should be easy to install and disassemble, so that the operation can be completed quickly during maintenance and replacement.

4 Conclusion

High voltage harness design and connector selection have become key factors to ensure the performance and safety of new energy vehicles. In this paper, the design of high-voltage wiring harnesses of new energy vehicles and the selection of connectors are deeply discussed to provide reliable and efficient solutions for the electric system of new energy vehicles.