Laminated busbars: what are they and how are they used?

Busbars have been dubbed as the “backbone” of many power applications today. It’s a no-brainer then that busbars are also being used with electric vehicle batteries.

As EV batteries generate electricity, a battery busbar efficiently distributes the current flows between the elements within an EV’s systems and subsystems. Its structure is also important in terms of form constraints and thermal management.

Here, we focus on laminated busbars–their functions and the advantages they bring, and a brief comparison with another busbar type, the flexible busbar.

What are laminated busbars?  

These are end products of assembled layers of conductive metals, particularly copper or aluminum. These layers are separated by paper-thin layers of dielectric materials. Heating and compressive processes are then applied to form a rigid, integrated component which is connected with a platoon.

Laminated busbars come in specific forms–strips, solid rods, bars, or tubes–which are based upon the current and performance requirements in which they will be used. Because of the increasing compactness and complexity of new-generation applications, like those found in EV batteries, laminated busbars provide improved attachments to these applications with the use of specialized connector systems (such as the Ennovi BusMate power busbar connector), without using traditional assembly processes (e.g., soldering, welding, bolting, or clamping).

How are they used?  

Laminated busbars essentially serve as conductors to power-generating components within an EV electrical system. They transfer the electrical energy EV batteries produced to the EV’s inverter. This energy is then converted into AC electricity which powers the electric drive motor and other subsystems.

Due to its design, it is possible to have power distribution with a high-power density. This can be achieved by mounting directly on the busbar active components for high-power conversion, including IGBT semiconductors, and passive circuit elements like capacitors and EMI noise reduction filters. All of these components help to improve driving range and performance while conserving the volume of circuits.

Laminated busbars can also be used to dissipate heat in an EV. Heat generation is greatest along resistive junctions where the current flows in the EV’s power distribution system.

The use of thermal conductors copper or aluminum enable busbars to serve as part of an EV’s thermal path, with heat being diverted from the heat source to a heat sink or coolant reservoir.

What are their benefits? 

Improved Reliability

Traditional busbar systems are complicated because of the many interconnected parts and cables that take too much time to assemble. Additionally, components and cables are subjected to detrimental factors in their environment, such as vibration and heat.

Not only is there an increased risk for installation error, there may also be instances of vibration failure along the assembly points. In contrast to traditional busbars, laminated busbars have been pre-assembled with all the internal components fused into its frame, forming a sturdy and compact structure. There is very little risk for wiring errors or vibration failures.

Low Heat Dissipation

The conductive materials in the busbar systems are the right amounts to carry low- or high-power densities. These busbars not only result in low heat generation, but can also deliver excess heat to heat sinks or coolant reservoirs to maintain the right temperature in the EV’s various sub-systems.

Low Inductance

Inductance is the flow of electrical power through conductive material, leading to the creation of an electromagnetic field. In the presence of stray inductance in an EV, it causes interference in the car’s electronics, overheating, and ultimately system failure.

The layered charged conductors in this battery busbar plus the insulating dielectric material in between each layer cancels the electromagnetic fields – and inductance – that develops. This means a more efficient conduction system. Thus, laminated busbars are the best choices for very sensitive and critical EV power systems and subsystems.

Increased Capacitance

As the conductive materials work to cancel out inductance, they increase the busbar’s capacitance or its ability to store electrical energy in the EV battery.

Laminated Busbar Design

This too is a benefit because of its guaranteed improved structural integrity, flexibility, and reduced service costs. Earlier, we mentioned that its structure leaves no room for potential connection errors and failures as opposed to traditional busbars.

It is also customizable in order to meet the specifications of various power applications. Finally, thanks to a lower assembly time, service costs in production and busbar maintenance are lower.

What are their applications? 

Laminated busbars are versatile, making them popular in a variety of industries and applications.

They may be used extensively in the following applications:

• Automotive and Transportation – Electric and hybrid vehicles, power and hybrid traction systems
• Manufacturing and Industrial – Factories, motor drives, welding systems
• Energy – Power generation and conversion systems and equipment, power switch systems
• Datacom and Telecom – Communication base stations, cellular communications, telephone exchange systems, network servers, data storage systems, supercomputers
• Aerospace – Aircraft, military, and defense electronics

Laminated vs flexible busbars: what’s the difference?  

When it comes to busbar design in EV batteries, you may have heard of flexible busbars being recommended just as often as laminated busbars.

Their main similarity is that they are both multi-layered. However, while laminated busbars are sturdy and rigid structures, the same cannot be said for flexible busbars.

This battery busbar is made out of layers of copper foils which are tightly attached to mounting areas, using a process called diffusion welding. While the ends are rigid to enable connections, the middle of the busbar is kept flexible.

Laminated busbars are customized during manufacturing to meet power and space constraints. Flexible busbars are just as customizable, but their greater flexibility means that they can fit in small, tight, or curved spaces without compromising mounting strength. Their flexibility also means that they provide greater shock and vibration absorption.

Both busbar systems are at the forefront of a revolution of busbar technologies with new and improved capabilities. Not only can they guarantee improved driving performance in electric vehicles, but they can also be applied in various applications where efficient and safe electrical conduction is required.