A. Roc'h

Investigation of EMI noise transfer characteristic of variable speed drive system

Electromagnetic compatibility is becoming an essential consideration for variable speed drive systems. Many methods are proposed to predict the conducted electromagnetic interference level. They ask to model all components of the drive system including cable and motor. In this paper, it is supposed that the measured noise level is determined in two phases. The first is the main noise source level and the second is the conversion efficiency from main noise source level to measured noise level. The noise transfer characteristic is investigated to understand the conversion mechanism. A transfer ratio is defined afterwards which is independent of the cable and motor. It can be used to evaluate the EMC design of a converter. A simplified model is used to explain this characteristic. Laboratory tests on a 12 kW PWM drive system are carried out to verify this hypothesis. Thorough test results are included in this paper

Analysis of Common Mode Inductors and Optimization Aspects

The common mode inductors, or common mode chokes, are a key component of electromagnetic interference filters. Engineers usually face significant design challenges such as size, cost and weight while working with these components. To avoid the construction of several prototypes, often oversized, engineers need an analytical method to predict performances of the filter. The analysis of the common mode inductors starts with a presentation of the different ferromagnetic materials: their properties are the cornerstone of the design of the component. Based on this study, the impedances used to characterize the choke are related to the designable parameters. The derived model shows the role of the parasitic currents to ground and the common mode impedance in the overall common mode current attenuation. A certain attenuation of differential mode current is also to be expected due to the parasitic currents of the common mode choke itself: the turn to turn capacitance and the leakage inductance. This model is validated by measurements. Sensitivity studies provide an additional insight into the behavior of the choke by giving an understanding on how variations of parameters, influence the final performance. The deviation calculation and the influence of the designable parameters are addressed at the end of this chapter.

Contributing factors in the final performance of a common mode choke

In order to avoid retro-designed common mode chokes in power system application, a predictive model is used to analyze the contributing factors in the final in-situ performance of the component. Designable parameters, together with environmental and installation aspects are analyzed. A hierarchic order of importance in term of influence in the final in-situ performance is proposed in the conclusion.

A pseudo-spectral longitudinal expansion in a spectral domain integral equation for scattering by periodic dielectric structures

We explore several options to introduce a pseudo-spectral expansion along the longitudinal direction in a spectral-domain integral equation for scattering by periodic dielectric structures. To this end we first simplify the integral equation to the formulation for a one-dimensional dielectric slab and consider the computational efficiency, convergence, and conditioning of several schemes. One scheme has been implemented in the domain integral equation and it exhibits exponential convergence with respect to the number of expansion functions in the longitudinal direction.

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 Pocklingtons 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.