EMI Simulation Speeds Design

Barco of Toulouse, France, recently brought a new ruggedized military computer to market 20% faster than in the past by using electromagnetic interference (EMI) simulation software. Previously, Barco built and tested multiple prototypes to address electromagnetic compatibility (EMC) issues which delayed the design process. On the current project, they used FLO/EMC from Flomerics to identify EMC issues early in the design cycle, well before physical prototypes were built.

“The first simulation helped us understand the problem,” said Jean Philippe Tigneres, environmental group manager for Barco. “Seeing how the waves were emanating from the box made it clear that EMI was not escaping uniformly from the openings but rather that certain locations were much more critical. We used this information to change the shape of the openings, providing shielding in the most sensitive areas while opening up others that were less critical. Over a few iterations, we were able to generate a design that met our EMC requirements in terms of shielding effectiveness, without reducing airflow.”

Barco’s Toulouse operation designs, develops and produces rugged laptops and workstations embedded on defense and security vehicles as well as consoles for aircraft or naval applications. The product mentioned here is a custom computer specially designed for a defense and security application. It required extra components that dissipate more heat than standard products.

Tigneres addressed thermal management issues first by modeling the new design using Flotherm software from Flomerics. Increasing the size of the inlet and outlet panels on the computer improved airflow and reduced junction temperatures to acceptable levels, but raised EMC concerns. Normally, designers would have addressed these concerns by building and testing several prototypes during the early, middle and late stages of the design process. The design process was often on hold during that prototype period because management did not want to expend additional resources on a design whose EMC performance had not been validated.

In this case, however, Tigneres used FLO/EMC to identify EMC design issues early in the design cycle, well before physical prototypes were built. FLO/EMC uses the transmission line matrix (TLM) method for solving Maxwell’s equations, which solves for all frequencies of interest in a single calculation and therefore captures the full broadband response of the system in one simulation cycle. “The user-friendliness and modeling speed of the software makes it ideal for use by design engineers,” Tigneres said.

The solution to the initial model showed that the larger openings had less impact than expected on EMC because of the larger than expected shielding provided by some of the internal components. Based on this understanding, Tigneres was able to produce an acceptable design from an EMC standpoint prior to building prototypes.

“Simulations help our designers to optimize our products from an EMC perspective to a level that wasn’t possible in the past, because we can evaluate more designs than we could ever prototype, and because simulation provides more information than testing,” Tigneres said. “At the same time, we are reducing the number of prototypes required, which saves time and money.”

For more information, visit www.flomerics.com