Modeling the common mode impedance of motor drive systems using the antenna wire concept

To describe radiated emission from cables in motor drive systems, a radiating (thin) wire antenna can be used. This equivalence allows the common mode impedance of the cable in such a system to be modeled as the input impedance of the antenna. Using a method of moments implementation for solving Pocklington´s equation for a vertical wire antenna above a perfectly conducting ground plane, a fast and flexible numerical model for the input impedance of the antenna is presented. Validation with measurements shows that the model captures the relevant behaviour, thus allowing it to be used effectively as a first step in the design process of motor drive systems.