A Systematic Approach to Quantify Electromagnetic Interference Risk by Cloud Modeling

Electromagnetic interference (EMI) can lead from minor performance degradation to a complete failure of an electric or electronic system. Therefore, particularly for safety-critical systems, risk assessment is the first step to quantify the effect of EMI on a system, allowing remedial modifications to reduce risk. Risk is a multidimensional function that depends on several factors, such as the EMI scenario, frequency of occurrence, and threat to the system. Often, electromagnetic compatibility (EMC) specialists or reliability engineers subjectively rate these variables based on EMI tests or conceptual understanding of the system. Subjective ratings, such as “low”, “medium”, or ”high“, are not always satisfactory due to the stochastic and fuzzy nature of subjectivity. Here we introduce the so-called cloud model which is a useful tool to address the problems associated with subjectivity. The cloud model is analyzed and used to present a general and systematic approach to quantify the risk of EMI in a system, inspired by a specific case study of an onboard railway signaling system.