Electromagnetic interference (EMI) in E-vehicles

October 12, 2011 // By Reinhard Felgenhauer, Delphi Deutschland
Electric propulsion brings with it high voltages which challenge vehicle electrical/electronic architecture. Delphi Automotive is continuing to build its HEV/EV expertise through new and complex simulation methods.

The cabling system in a car is comparable to the human nervous system. As long as it works perfectly, no one recognizes it. If it fails, it's a disaster. Often several processes and applications are impacted or stop functioning altogether.

The enormous increase of electrical and electronic components in hybrid and electric vehicles places increasing importance on the electrical distribution system with respect to quality and reliability of data transmission. Distribution systems use different standards of high-speed data transmission. A flood of data has to be processed, reliably transmitted and the system has to avoid interferences and disturbances.

Currently, up to seven CAN bus systems are incorporated into a vehicle. High amounts of data are transmitted by Flexray and MOST Systems, additional USB and Ethernet links. All systems transmit different amounts of data and have different data transmission standards.

This flood of data in vehicles and the high amount of data transmission systems requires complex data management – and equally sophisticated technical hardware. For this reason, dedicated characteristics for electromagnetic interferences (EMI) and electric and electronic components in hybrid and electric vehicles are required.

In these vehicles, electrical shielding is also required to avoid electromagnetic interference between components and functions.  USB interfaces, for example, which are incorporated into a growing number of vehicles to attach mobile music players, have to be shielded to avoid interferences between functions and electrical components.

Shielding is state-of-the-art and the subject of ongoing optimization. The challenge for developer is miniaturization, more cost-effective design and weight reduction, and uniform quality levels for all production plants worldwide.

At the beginning of the e-mobility movement, we see additional challenges. Beside the existing 12V electrical system in vehicles, which is required for driver assistance systems, radios, navigation systems and several other features, a high-power electrical/electronic system will be integrated into electric vehicles. This result will be a system requiring 300 - 400 volts or more.

The high-current, high-voltage operation

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