Hongbao
Upgrading the copper-aluminum connection process for high-voltage wiring harnesses in new energy vehicles, with plasma welding equipment leading the trend
Published Time:
2026-01-15 10:32
In the process of the new energy vehicle industry's accelerated evolution towards 800V high-voltage platforms and 1500V motor systems, the lightweight and high-efficiency of high-voltage wiring harnesses have become the core bottleneck restricting the industry's development. As the "neural network" for electric energy transmission, the copper-aluminum connection process of high-voltage wiring harnesses directly determines the safety, endurance, and manufacturing cost of the entire vehicle. In this technological revolution, plasma welding equipment, with its unique process advantages, is becoming a key force driving the upgrading of copper-aluminum connection technology.
Traditional high-voltage wiring harnesses for new energy vehicles often utilize pure copper conductors. However, copper prices have long remained above 80,000 yuan per ton, and with a density of up to 8.96g/cm³, the weight of the wiring harness accounts for more than 60% of the total vehicle wiring harness. As the 800V high-voltage platform becomes more prevalent and charging currents exceed 600A, if copper conductors are continued to be used, cables with cross-sectional areas of over 120mm² would be required. This not only increases the overall vehicle weight but also reduces the driving range. Although aluminum conductors have only one-third of copper's density and cost less than 40%, their conductivity is only 60% of copper's, and the difference in thermal expansion coefficients between copper and aluminum is 2.3 times, with a potential difference of 2.34V. This leads to the formation of brittle intermetallic compounds (IMC) at the connection interface, causing issues such as a surge in contact resistance and electrochemical corrosion.
Taking Tesla as an example, the high-voltage wiring harness between its motor controller and battery pack contains more than 20 copper-aluminum connection points. The thickness of intermetallic compound (IMC) layers such as CuAl₂ and Cu₉Al₄ formed by traditional argon arc welding processes reaches 80-120μm, resulting in an additional heat generation of 1.2kWh per connection point due to annual resistance loss, which is equivalent to a reduction in driving range of 5-8 kilometers. More critically, under extreme temperature variations ranging from -40℃ to 150℃, the IMC layer is prone to cracking, causing contact resistance fluctuation rates to exceed 200%, posing a serious threat to driving safety.
Plasma welding technology achieves precise fusion of copper and aluminum through high-energy plasma arc (with a temperature of up to 20,000℃). Its core advantages are reflected in three aspects:
1. Precise control of heat input
The plasma arc energy density is more than five times that of traditional argon arc welding, which can strictly control the temperature of the copper-aluminum contact surface below 548°C (the eutectic point of copper and aluminum). Shandong Hongbao Automation's plasma welding equipment utilizes digital twin technology to simulate the welding process. By adjusting gas flow rate (argon/nitrogen mixing ratio), current (200-500A), and voltage (20-40V) parameters, the thickness of the intermetallic compound (IMC) layer is compressed to 15-18μm, a reduction of 80% compared to traditional processes. Actual measurement data shows that the contact resistance of the joint under this process increases by only 15% compared to a pure copper joint, and the resistance fluctuation rate after 100,000 thermal cycles is less than 5%.
2. Microstructure optimization
The penetrating power of plasma arc can destroy the oxide film (Al₂O₃ thickness up to 3-5μm) on the surface of copper and aluminum, while forming a mechanically interlocked structure through high-speed rotating welding guns (3000 rpm). During the welding process, plasma welding equipment simultaneously injects a nano-graphene coating, reducing the corrosion rate to 0.001mm/year and extending the salt spray test life by 8 times. In the battery pack wiring harness test of BYD's AYTONG U8, the connection points using this process maintained an insulation resistance of >100MΩ after 1000 hours of salt spray testing.
3. Leap in production efficiency
The speed of plasma welding has been increased by over 50% compared to traditional processes. Tesla's Shanghai Gigafactory has introduced 12 fully automated plasma welding production lines, which have increased the output from 800 to 1500 units per shift, with a product pass rate of 99.7%. Its AI vision system can monitor changes in temperature and pressure fields during the welding process in real time, controlling process parameter fluctuations within ±2% to ensure that the mechanical properties (pull-off force >28N/mm) and electrical properties (temperature rise <34K at 380A current) of each connection point fully meet the standards.
The breakthrough in plasma welding technology is driving profound changes in the electrical architecture of new energy vehicles: material compositization, intelligent monitoring, and internationalization of standards.
As the purchasing director of an international automobile company once said, "When the plasma arc illuminates the copper-aluminum interface, what we see is not only the fusion of materials, but also the future direction of the entire industry." This shows that the application of plasma welding equipment in the new energy vehicle industry is not just a tool, but also a core engine for reconstructing the electrical architecture of new energy vehicles.
welding equipment