Foundations and Integrations of Computational Electromagnetics Part 2: Electromagnetic Compatibility

All electronic devices must meet electromagnetic compatibility (EMC) requirements for government regulations and quality standards. Across industries, design teams seek to reduce physical prototypes and the risk of test failure using digital simulation technologies.

In the previous installment of this series, we described the computational electromagnetic concepts underlying modern simulation techniques. The full-wave electromagnetic, transmission line theory, transient circuit, and fluid solvers are the fundamental technologies that enable simulation.

This discussion will describe the platform technologies that enable importing of design information, co-simulation techniques between multiple solvers, and optimization tools used for EMC simulation to guide design and certification of products.

Implications of Electromagnetic Compatibility Simulation

EMC concerns impact product development teams across a wide range of industries. This is a consequence of the “electrification” of consumer, industrial, and military/aerospace designs. The electronic components in these designs are integral to the creation of new products to enhance feature sets, expand addressable applications, and improve overall reliability and functional lifetime.

As EMC certification becomes the norm for developers, virtual prototyping is an essential component of many design methodologies. There are many advantages to prototyping designs. For example, failing EMC testing and correcting problems early in the design cycle is much less expensive than experiencing the same failure late in the design process or during testing and verification of a physical prototype. Early software prototyping also reduces the probability of an EMC certification test failure later on.

The occurrence and consequences of EMC test failures are not trivial. As an empirical rule of thumb, the lack of a virtual/software-based prototyping workflow early in development can result in 50% of new products failing one EMC test and roughly 30% failing either multiple tests or the same test repeatedly.¹

Software-based prototyping is increasingly based on employing a suite of tools. Combined with new techniques to reduce the initial analysis effort, mechanical and electronic computer-aided design (CAD) permit rapid development of simulation models that are accurate representations of the actual product. The goal, of course, is to design better products by understanding and predicting electromagnetic interference (EMI) hazards. Optimization and model-based systems engineering (MBSE) enable design trade-offs before any physical prototypes are developed.

But this leads to some very natural questions from the product developers:

1. What are the tools and techniques that lead to successful EMC-based design projects?
2. What makes a given selection of tools appropriate for EMC design?
3. What workflows should be applied to a tool suite to achieve effective EMC design?

The Foundations and Integrations of EMA3D for Electromagnetic Compatibility Designs

Ansys and EMA will discuss these questions in great depth in the second installment of the “Foundations and Integrations of EMA3D” webinar series. The webinar, on September 22, will go into technical detail on the following topics:

• Full-wave electromagnetic co-simulation using finite difference time domain (FDTD) solution and multiconductor transmission line (MTL) theory. We will explain how the fields are exchanged between the two solvers and describe specific EMC cases in which the co-simulation is used for EMC analysis. Finally, we will give details on how the co-simulation of FDTD and MTL in Ansys EMA3D Cable enables important EMC-relevant effects, such as the proper modeling of poorly terminated cable shields.
• Grid-based FDTD mesh technologies. We will describe how EMA3D goes beyond volumetric voxels to include surfaces and lines. We will describe sub-cell simulation techniques that enable the inclusion of seams, gaps, and thin cables that are smaller than the computational mesh cell. Finally, we will describe how these features are combined to use mechanical and electronic CAD with no analyst simplification required.
• Transient circuit solvers. We will explain how FDTD, MTL, and transient circuit solvers can all be co-simulated to solve relevant problems in EMC. We will describe real-world cases in which all are needed to properly model physical scenarios. This includes quickly designing front-end circuit elements to protect systems from EMC effects and seeing the results simulated immediately.
• Fluid and electromagnetic co-simulation. We will show how full-wave electromagnetic solvers are coupled with fluid solvers and models of the ionization of air to allow for arcs and discharges. We will specifically show how this is applied to electrostatic discharge (ESD) modeling for electronic devices.
• Platform integration. We will discuss how mechanical CAD, electronic CAD, cable harness design files, and material property databases are integrated seamlessly in Ansys platform tools. We will show how results from Ansys SIwave and Ansys HFSS may be used within EMA3D simulation to add the impacts of enclosures and cables. We will describe how this enables interdisciplinary collaboration, time savings, and more accurate simulation for EMC and related environments. We will show how workflow improvements mean that certain EMC analyses may be performed by nondomain experts quickly and accurately.
• Optimization and collaboration. We will discuss how Ansys optiSLang and Ansys ModelCenter may be used with EMA3D to enable optimization, trade-off studies among multiple disciplines, and MBSE. We will describe scenarios where EMC must be considered at the same time as other design considerations. We will give concrete examples of how a design change may be automatically re-simulated for EMC with the resulting impacts on meeting requirements returned to the MBSE software for evaluation.

We look forward to seeing you at the webinar and answering your questions. Sign up for the webinar here.

Resources

1. Why 50% of Products Fail EMC Testing the First Time, Intertek Testing Services NA Inc.