Introduction

At present, the competition in the domestic new energy vehicle market is becoming increasingly fierce. With the price reduction of domestic Tesla and the entry of Volkswagen's electric models, the competition will become even more intense in the future. Only by relying on high-quality, high-value products and leading technologies can automotive enterprises secure a place in the highly competitive new energy vehicle market. While major automakers are constantly innovating in technology, they are also focusing on optimizing component costs, enhancing product quality and improving corporate competitiveness. High-voltage wiring harnesses are high-value components in pure electric vehicles and are also the main parts for cost optimization.

Introduction to High-voltage Wiring Harnesses and Their Production processes

High-voltage wiring harnesses connect various components of the high-voltage system and serve as the medium for high-voltage power transmission. They are the main carrier of power output in electric vehicles and are mainly used for transmitting electrical energy and shielding external signal interference. High-voltage wiring harnesses feature high voltage, large current, high protection level and resistance to electromagnetic interference. They serve as the neural network of the high-voltage system in pure electric vehicles and are key components for the overall performance and safety of the vehicle. High-voltage wiring harnesses for pure electric vehicles are generally classified into high-voltage wiring harnesses for power batteries, high-voltage wiring harnesses for motor controllers, fast charging socket wiring harnesses, slow charging socket wiring harnesses, air conditioning system wiring harnesses, and charging high-voltage wiring harnesses. Among them, the charging high-voltage wiring harness refers to the wiring harness that connects the high-voltage distribution box to the on-board charger, air conditioning compressor, and the heater of the power battery pack.

High-voltage wiring harnesses are mainly composed of high-voltage connectors, high-voltage cables, covering materials (such as tapes, heat shrink tubes, corrugated tubes, wear-resistant self-winding tubes, etc.), and protective plates, etc. The main production process of high-voltage wire harnesses includes wire cutting, pre-installation of accessories, terminal crimping/ultrasonic welding, shielding crimping, final assembly of wire harnesses and electrical inspection.

Analysis of the cost Structure of High-voltage wiring harnesses:

The cost of high-voltage wiring harnesses consists of material costs, processing fees, packaging and transportation fees, and management fees. The material cost of high-voltage wiring harnesses is mainly determined by the technical solution of the wiring harness. Among them, processing fees include labor costs, power costs, equipment depreciation costs, and low-value consumables, etc. The material cost of high-voltage wiring harnesses accounts for approximately 73.8% of the total cost of wiring harnesses. It is necessary to continuously reduce the cost of high-voltage wire harnesses through methods such as optimizing design and production processes.

Research on Cost Optimization of High-Voltage Wiring Harnesses

There are mainly three types of methods for automotive industry enterprises to reduce costs: scale-based, supplier collaboration, and technology-based cost reduction. Among them, technology-based cost reduction is the most effective and sustainable way to cut costs. At present, there are mainly three methods for reducing costs through technology: cost benchmarking method, management technology method and technical means method. Under normal circumstances, the technical means approach includes methods such as reducing redundant functions, increasing the domestic production rate, and standardizing and platformizing specifications. In the cost reduction campaign for high-voltage wiring harnesses of pure electric vehicles, this time the main research focuses on optimizing the cost of high-voltage wiring harnesses from the following aspects through technical means. 01 Optimization of High-voltage System architecture

On pure electric vehicles High-voltage components include power batteries, three-in-one (motor controller + drive motor + differential reduction), PDU (high-voltage distribution box), ECP (electric compressor), two-in-one (IPS=OBC+DC-DC), HVH (battery heating), PTC (occupant heating), slow charging seat (ACInlet), and fast charging seat (DC) The components such as Inlet and high-voltage wiring harnesses make up the high-voltage system of the entire vehicle. A well-optimized high-voltage system architecture for pure electric vehicles can significantly reduce the number of connectors used and redundant high-voltage wiring harnesses.

02 Optimization of High-voltage wiring Harness layout

The layout of high-voltage wiring harnesses needs to be continuously optimized according to the vehicle model. After optimization, the use of high-voltage cables can be reduced, further lowering costs.

In the cost structure of high-voltage wiring harnesses, material costs account for the highest proportion. Analyzing the current situation, the main directions for material optimization of high-voltage wiring harnesses at present are the integrated design of charging sockets, the localization of high-voltage connectors, the optimization of high-voltage cable diameters, and the optimization of one-to-many material options.

03.1 Integrated design Optimization of Charging sockets

Before optimization, the charging socket was designed as a split type, which was relatively costly. The split charging socket before optimization is shown in Figure 7, including a fast charging socket and a slow charging socket. The charging sockets were developed and designed in accordance with the platform-based solution. The main structure of the charging sockets for all projects was solidified to minimize the development cost. The optimized integrated charging sockets are shown in Figure 8. This optimization can reduce one set of flange molds, thereby lowering the cost of the high-voltage wiring harness assembly by approximately 8 yuan.

Figure 7 shows the split-type charging socket before optimization

Figure 8 shows the optimized integrated charging socket

03.2 Localization of High-Voltage Connectors In recent years, the high-voltage connector industry has developed rapidly, and a number of outstanding domestic high-voltage connector brand suppliers have emerged. Before optimization, mainly foreign brands such as TE were used for high-voltage connectors. Through continuous optimization of the localization of high-voltage connectors, domestic brands like Luxshare and Ebusbar were adopted for domestic substitution, which is of great significance for reducing the cost of high-voltage connectors.

03.3 Optimization of High-voltage line cable diameter

Optimize the cable diameter of high-voltage lines through measures such as interpreting regulations, benchmarking and statistically analyzing cloud big data. For specific high-voltage cables, it is often possible to tailor them to the specific needs by optimizing the cross-section, temperature requirements, flexibility and shielding effect, to avoid excessive size and excessive components. Take the fast-charging high-voltage cable as an example. The diameter of the frontline cable was optimized to 70mm ², and after optimization, it became 50mm ², both of which can meet the actual charging requirements.

03.4 Material one-to-many optional optimization

The one-to-many high-voltage wire harness material can fully mobilize the enthusiasm of tier1 suppliers and leverage their own supply chain advantages to select the most cost-effective solution for supply. Take high-voltage cables, which account for a relatively high proportion of material costs, as an example. Currently, the main specifications of high-voltage cables are developed in accordance with the high-voltage cable standards based on the one-to-many approach. For each specification of the wire harness factory, there are multiple specifications to choose from. The specific application of conductors in each circuit needs to be confirmed based on the actual load of the entire vehicle. Through continuous optimization of design, many materials can now be selected in a one-to-many manner.

04 Platformization and standardization design:

By conducting platformization and standardization design from aspects such as the principles and raw materials of the vehicle wiring harness, the development cycle of the vehicle wiring harness design stage can be significantly shortened, repetitive verification tests can be reduced, and the cost of the wiring harness can be lowered. Through the continuous platformization and standardization of wire harness materials, the types of materials have been reduced, and increasing the quantity of a single material can achieve a scale effect, which is of great significance for reducing material costs. After research and analysis, it is found that the platformization and standardization solutions for secondary materials (connectors, cables, auxiliary materials, etc.) can significantly reduce the material costs of high-voltage wire harnesses.

Summary and Prospect

Due to the characteristics of high voltage, high current, large wire diameter and a large number of conductors, the high-voltage wiring harness of pure electric vehicles is confronted with challenges such as wiring, safety, shielding, weight and cost. As a high-value component of pure electric vehicles, high-voltage wiring harnesses can contribute to reducing the overall cost of the vehicle through continuous cost optimization through research. Cost reduction is a continuous and ongoing activity that needs to be further optimized in the future to minimize the overall vehicle cost and provide customers with more competitive products.