Electric cars should charge safely and quickly, and the electrical installations should be light and compact. Busbars offer these advantages over traditional cables, and with electromagnetic pulse technology (EMPT), a mass-production-capable, cost-efficient manufacturing method is also available.xiaoliangge - stock.adobe.com
A disadvantage of electric cars is still the charging time. The integration of busbars in charging infrastructures for electric vehicles offers great potential to increase this charging performance. However, some challenges need to be addressed.
And very importantly: Busbars do not burn. High charging capacities require high currents with corresponding heat development. Busbars can dissipate this heat, thus preventing overheating and can therefore transmit the necessary higher currents. Thanks to lower inductance and higher capacity compared to cables, they also make charging more efficient and cause less electromagnetic interference.
Moreover, installing busbars takes only about a third of the time of cable installation, and in an energy distribution system, you are even 70% faster, as the rigid busbars can be automatically installed more easily than the flexible cables.
Additionally, the rigidity of the busbars provides a stability moment for the car, offering long-term reliability in harsh environments and withstanding operating temperatures from -40 to +125 °C.
Busbars, unlike cables, consist of type-tested and pre-assembled standard components. Planning a busbar system is therefore significantly simpler, faster, and cheaper than a cable solution. Here, tap-off points are already provided at intervals of a few centimetres and only need to be activated. This allows adjustments and changes to busbar systems to be easily and cost-effectively implemented both during installation and after completion.
What requirements are placed on the materials of busbars?
Busbars in cars are often exposed to moisture and chemicals, which is why corrosion-resistant materials are needed. The basis for power cables is usually expensive copper. Both aluminium and copper have high thermal and very good electrical conductivity. For cost reasons, most of it should be made from inexpensive aluminium, but expensive copper is needed for the contacts. However, when the two metals and condensation come together, a violent electrochemical reaction starts: the copper decomposes the aluminium, contact resistance and temperature increase, and in the worst case, a fire occurs. In addition, the two metals are not easy to join, partly due to their different thermal expansion, so manufacturers often choose only copper or aluminium.
The Automotive Battery Congress
Electromobility will be one of the main drivers in the automotive industry in the coming years. The battery plays one of the most important roles in the global spread of electric vehicles, with the decisive factors being battery range, charging options, and financing of production costs. All these topics are covered in the next edition of "The Automotive Battery" from 1st July to 2nd July 2026 in Munich.
The advantages of EMPT technology in welding busbars
To make the best use of the performance of busbars in charging devices, manufacturing methods such as punching, milling, sawing, etc., are no longer sufficient. 3D printing and EMPT technology (Electromagnetic Pulse Technology) are suitable here. Additive manufacturing allows complex geometries to be produced with high precision and functional elements to be integrated. Unfortunately, the acquisition costs for the equipment are enormous, the component sizes are limited, and manufacturing takes time. EMPT offers affordable equipment and operating costs and, above all, allows the technique to join aluminium and copper quickly and reliably.
"The EMPT technology works quickly, is easily automatable and safe. The welds produced with it are mechanically extremely stable, have the lowest resistances and are helium-tight, i.e., no corrosive medium can penetrate. Additionally, the restrictions regarding the geometries of the parts to be joined are less significant than with other processes," summarises Dr. Ralph Schäfer, Head of Research and Development at PSTproducts.
The welds produced with EMPT technology are mechanically very stable, have low resistance, and are helium-tight.PSTproducts
What does an EMPT system consist of and how does it work?
The most important components of such an EMPT system are the pulse generator, control cabinet, and depending on the application, flat coils or field shapers. Pulsed currents in the range of several 100 kA to over 1000 kA can be generated here. However, the required mains connection power is limited to 380V/64A even for powerful systems due to the 3 to 8 seconds charging time of the capacitors.
EMPT welding is based on an electromagnetic pulse, shorter than 100 µs, with a power consumption depending on the system size between 0.015 and 0.03 kWh per pulse. The pulsed current has a very high amplitude, typically several 100 kA, discharge frequencies between 10 and 50 kHz, and generates a strong magnetic field that induces an eddy current in one of the workpieces. The two workpieces are positioned overlapping, with an acceleration gap in between. During the joining process, the coil accelerates one of the two workpieces and lets it impact the stationary joining partner at up to 500 m/s.
In the collision area, extremely high mechanical stresses and strains occur. The maximum stress occurs at the point of contact and creates a kind of bow wave in front of the joining area. This plastic deformation breaks up the superficial oxide layers of both contact partners. The air gap between the workpieces is compressed, blowing out all dirt and chipped oxide particles from the joining area.
The two surfaces are pressed together under such enormous pressure that the atoms of the joining partners form a metallic bond. Since the melting point of the joining partners is by far not reached, metals with different melting points can be joined without distortion. The joining zone generally has a higher strength than the weaker base material. EMPT welding therefore works without increasing temperature and without structural changes, i.e., without a weakening heat-affected zone and without the formation of intermetallic phases, as can occur when joining with lasers, ultrasound, etc.
Another major advantage is that when welding aluminium and copper with EMPT, the transition resistance does not increase, and the good conductivity of the two metal partners remains across the joint.
When welding aluminium and copper with EMPT, the transition resistance is not increased, and the good conductivity of the two metal partners across the joint remains intact.PSTproducts
EMPT welding of busbars is suitable for mass production
EMPT welding delivers high-quality weld seams without the use of shielding gases or welding additives.
The pulse generators and coils from PSTproducts easily achieve service lives of over two million pulses. Depending on the design and tool, a system can perform 1 to 5 million environmentally friendly welds per year. The magnetic field and thus the welding parameters are very precisely controllable, providing consistent, documentable quality.
With an EMPT system, up to 10 busbar connections per pulse can be carried out with cycle times from 5 seconds, making this welding process commercially cost-efficient. This allows mass production in quantities of tens of millions per month.
"At PSTproducts, we have extended the lifespan of pulse generators and coils by selecting suitable materials and optimising system technology, increased maintenance intervals to 500,000 - 2,000,000 pulses, and reduced joining costs to just a few cents. The availability of EMPT systems allows for 100% process control and use in fully automated production lines," reports Ralph Schäfer.
There is only one limitation for EMPT welding: the materials must be electrically conductive.
Future developments in E-car charging technology
The charging technology for E-cars is undergoing rapid change. What innovations will be possible also depends on the development of new materials, material combinations, and their processability. Thanks to the possibilities offered by additive manufacturing and especially the EMPT process, there are great opportunities to drive the development of new technologies forward.
