The Flat Design Is Not The Only Advantage of High-Voltage Busbar

From fuel vehicle to electric vehicle, the transformation of vehicle acceleration has promoted a new understanding of vehicle architecture. OEM has realized that the architectural breakthrough brought by electric vehicles is a great opportunity to optimize the whole vehicle components, even the basic construction of electrical architecture.

This innovative spirit even extends to the wiring itself. OEM is taking a flat conductor (called high-voltage bus) as an alternative to the traditional cable. Compared with the traditional cable, the high-voltage bus can load more power and save the space in the vehicle to the maximum extent, making it easier for the vehicle to be automatically assembled, thus reducing the cost and improving the safety.

However, although high-voltage buses have obvious advantages in some applications, they also have some limitations. A company solves these bottlenecks through innovative solutions and helps OEMs lay a better foundation for the next generation of electric vehicles.

For more than a century, round cable can be regarded as the basis of all kinds of electrical connections. Flexibility is the key to their popularity: they can bend around obstacles such as corners through narrow spaces, and each end is equipped with connectors, making installation easy. These advantages are usually reflected in the vehicle electrical architecture. However, there are several factors that lead OEMs to increasingly choose conductors called high-voltage buses as substitutes for cables in some applications.

High-voltage bus bars are solid metal bars used to carry current. They are usually flat and made of copper or aluminum. They are wider than cables, but their height is 70% lower than that of cables. Compared with cables with the same cross-sectional area, they can carry more current. With these characteristics, high-voltage bus has become an ideal choice for some high-voltage connection applications in electric vehicles (EVs), and it will also become a key component of the future automotive electrical architecture.

The primary driving factor for the application of high-voltage bus is the lack of internal space in today's vehicles. Every sensor, actuator, electrical/electronic equipment, etc. in the vehicle needs power supply and data lines, and the packaging space matched with them. Because the height of the high-voltage bus is lower than that of the cable, its lower wiring structure makes room for other electrical components. Compared with cables, they can more closely and accurately fit various wiring angles and fully adapt to the vehicle structure.

The second driving factor is the demand for automated assembly. Although the vehicle assembly has been automated to a great extent, the installation and wiring still rely mainly on manual work. Because of the flexibility of the harness, it is difficult for the mechanical arm to clamp and place it in the correct position in the vehicle.

In contrast, it is much simpler for the mechanical arm to move the rigid high-voltage bus to the proper position.

From the perspective of labor force, automatic assembly is cheaper, higher in quality and safer, because electric vehicles have high running power, and automatic assembly makes workers avoid the potential danger of contact with heavy current.

The third driving factor of high voltage bus application is that it can carry more current. OEM is seeking to increase the power of electric vehicle battery to shorten the charging time, while the high-voltage bus with the same cross-section can carry 15% more current than the cable.

In addition, the surface area of high-voltage bus bar is larger, and it can dissipate heat more effectively than cables of the same length-another advantage that can help OEMs improve their power level.

"This innovative spirit even extends to the wiring itself. OEM is taking a flat conductor (called high-voltage bus) as an alternative to the traditional cable. Compared with the traditional cable, the high-voltage bus can load more power and save the space in the vehicle to the greatest extent, making it easier for the vehicle to be automatically assembled, thus cutting costs and improving safety. "

The above factors make high-voltage bus an attractive choice, but there are still several obstacles to be overcome in order to realize its wide application.

The automobile industry has a long and rich practical experience in connecting cables and equipment with connectors, which can easily and safely insert, fix and lock cables in place. At present, most manufacturers still use bolts as the connection points of high-voltage buses.

Although bolts can play a role, they have several disadvantages. It takes more tools and labor than bolt connectors to install, and OEM must measure the torque applied to the bolts to ensure that the bolts are tightened.

In addition, when assembling automobiles, OEMs want to avoid using possibly scattered metal parts (which will lead to short circuit of electrical components), and bolts are one of the components that must be considered. Although the industry has not yet formulated a unified standard for the interface of high-voltage connectors, we know that the ideal connector must be safe when touching fingers to prevent accidental contact, and it should also minimize fretting wear and allow position tolerance.

A company has successfully developed the pluggable female terminal and the corresponding male-to-male high-voltage bus connector for the application of high-voltage bus, and fixed the high-voltage bus in place by using stainless steel springs that will not relax due to heat.

In some cases, it may be necessary to give a certain degree of flexibility to the high-voltage bus. If the high-voltage bus bar is difficult to bend, it may be difficult to install in place due to manufacturing tolerance. In addition, the tolerance of high-voltage bus is very poor, and the tolerance will be difficult to avoid considering thermal expansion or vibration.

For these reasons, OEM is looking for a solution to add a flexible component to the high-voltage bus, so as to maintain its advantages while creating a certain degree of flexibility. These components can be located at the terminal or somewhere in the middle of the high-voltage bus.

One method is to replace a part of the high-voltage bus with braided tape, which can keep the flat configuration, but it is too flexible for automatic assembly.

Another method is to replace a certain component of the high-voltage bus bar with sheets of conductive material, and then stack these sheets. This method can provide a certain degree of flexibility in a certain direction.

Like any electrical and electronic equipment, the current flowing through the high-voltage bus will also generate electromagnetic radiation, which may cause interference to the electronic equipment in the vehicle. With the continuous development of high-voltage bus, alternative shielding methods have to evolve.

Similar to cable shielding, high-voltage bus shielding uses the method of winding braided metal sleeves around the high-voltage bus. This method retains the advantages of high-voltage bus, such as flatter wiring and better heat dissipation than cable, while minimizing interference.

Today, high-voltage bus has been proved to be a valuable battery connector, which is applied to short-distance connection between battery modules in electric vehicles. Even in such a narrow space, some flexibility is needed to absorb vibration and provide tolerance.

As the application of high-voltage bus extends to areas outside the battery, OEM must consider the whole electrical/electronic architecture when making design decisions to decide whether to apply high-voltage bus, where to apply it, how to connect with other components, and where to add shielding or flexibility.

We have a long history in manufacturing innovative and reliable cables and connectors. With our expertise in wiring and connectors, we know how to design components and help OEMs solve their toughest challenges.

Most importantly, we consider these components on the premise of the overall automobile architecture. High-voltage bus is an indispensable component in the vision of Smart Vehicle Architecture put forward for future automobiles. Combining high-voltage bus with modular regional architecture and connection system will simplify the overall design of automobile architecture and realize more automatic assembly. Together, they will lay the foundation for the next generation of electric vehicles.