Electrical Distribution Dimensioning Tools and Solutions 2007-01-0518

Due to the ever continuous integration of new electronic functions onboard vehicle, the electrical power needs are increasing. Indeed the power demand increase has several impacts on energy distribution. New power generation systems such as hybrid are emerging. In order to increase vehicle availability and dependability, energy management is the key. Devices such as power switches and battery monitoring systems are implemented. In the meantime available space in the engine compartment is becoming crucial. Thus many cars have their batteries delocalized in the trunk. These major electrical architecture evolutions have to be studied in detail in order to optimize solutions cost while ensuring a high level of dependability. How to combine 30% of electrical power increase, 20% of weight and cost decrease while improving vehicle reliability at the same time?

In order to overcome these constraints we have developed a dedicated Electrical & Electronic Distribution Systems (EEDS) tool as well as specific products. The objective of the VALEO EEDS dimensioning tool is to ensure a high level of dependability and to optimize the cost of components. This tool integrates all the influent parameters such as load profiles, wires topology (splices, length…), protection devices (fuses, semiconductors…). The output of such a tool is a complete EEDS dimensioning proposal dealing with the protection types and ratings, the wires sections, and other many guidelines to achieve a safe and cost effective power distribution. This paper will present the methodology used to provide relevant models of EEDS components. It will describe the influent phenomenon which has been taken into account to make these models, such as thermal, chemical and electrical characteristics of all components. Thanks to these detailed models, interactions between all these parameters in a real condition can be simulated to choose the appropriate components.

We will illustrate this EEDS dimensioning tool with a concrete example based on the use of aluminum for rear battery connection. The connection between the battery and the engine is currently made with copper, even for rear batteries, which implies heavy and expensive harnesses. The use of aluminum allows a strong weight reduction, up to 30%, while optimizing cost, about 20%. The dimensioning of the aluminum bus bar as well as the link with copper extensions are key elements of such a product.