Study, measurement, and modeling of the propagation of conducted emissions due to on-board chargers in grids with various earthing systems

The transition to electric vehicles (EVs), driven by policies to decarbonize transport and significant technological advances in electrical energy storage and conversion, will continue over the coming decades. What's more, future on-board chargers (OBCs) with bidirectional power supply will contribute to greater grid stability, peak-shaving, and even improved integration of renewable energy resources: we're talking about the "vehicle-to-grid" (V2G) concept. This means that not only will the number of EVs increase, but also their charging and discharging times when connected to the grid.The need for compact equipment, favored by the availability of high-speed switching components (SiC GaN), has prompted manufacturers to increase the operating frequencies of OBCs (> 50-100 kHz), with the corollary of increasing their conducted and radiated electromagnetic emissions. As a result, these noise sources remain connected to the grid and operate for extended periods, making it necessary to anticipate potential Electromagnetic Compatibility (EMC) problems in energy networks: this is the general aim of this work.One of the subjects of this thesis concerns the standardized method of measuring conduct-ed emissions, in which the noise measurement impedance via the Line Impedance Stabilization Network (LISN) is not always representative of the impedance of the LV network, nor of course of its possible fluctuations. Thus, different grounding systems provide paths with different HF impedances, which can alter the level of emissions. Consequently, the discrepancy between the normative configuration with LISN and the actual impedance at the point of access to the power network can impact the effectiveness of EMC filtering, leading to potential malfunctions in neighboring systems and/or those connected to the same network.The need to analyze impedance variations and their consequences on EMC filters led us to develop and implement a methodology for measuring the RF impedance of the noise termination while operating at nominal mains voltage and in the absence of the LISN. This approach makes it possible to measure the line impedance of various equipment and power supplies, in particular, the distribution network. Based on these observations, the study of the impact of actual network impedance on the optimized volume of an EMC filter was approached through scenarios where different normative levels were considered.In order to examine the conducted emissions caused by our prototype bidirectional on-board charger in a controlled environment without LISN, a microgrid connected to the real net-work via an isolation transformer was built. This enabled us to control its parameters: source impedance, cable length, grounding system and to control impedance variations due to locally connected loads. Conducted emissions were then measured and analyzed at various points on the microgrid, according to different configurations (grounding regime and different loads on the microgrid).In parallel, a frequency model of the microgrid was established using a new approach based on the use of a SPICE-type solver and the experimental acquisition of elementary impedances, enabling faster simulation for large systems. This work was followed by rigorous verification procedures to ensure model accuracy and fidelity. A "black box" behavioral model has been developed for the OBC, defining the noise source and its impedances. This makes it possible to simulate parasitic current levels at any point in the microgrid, whatever the connected loads.As a result, the model of the entire system has enabled us to analyze impedance variations and conducted emissions in an extended version of the realized system. The thesis will present a synthesis of the results.