Understanding conducted emissions from an automotive inverter using a common-mode model

Abstract

This contribution presents results from an investigation into conducted emissions of an automotive inverter in a component level EMC test setup with unshielded cables. The primary goal of the investigation is to develop a profound understanding of the shape of the disturbance voltage's frequency spectrum at the line impedance stabilization network. Complying with that objective, common-mode currents are identified as the dominating noise currents, especially at the operating point of the inverter representing the worst case scenario regarding EMC performance. To support this conclusion, an AC simulation of a single-phase common-mode equivalent circuit of the system is presented. The resonances occurring in the noise spectrum and its overall shape are explained by the simulation within the frequency range of 100 kHz to 110 MHz. In addition, C Y capacitors are used as common-mode filter elements. Based on the validated simulation model, the influence of the filter capacitors and their parasitic inductances are investigated.

Measuring and Separating Conducted Three-Wire Emissions From a Fault-Tolerant, NPC Propulsion Inverter With a Split-Battery Using Hardware Separators Based on HF Transformers

“…For a complete CM/DM model, the DC link capacitors, including the busbars and their parasitics, would need to be considered as well. However, these do not significantly affect the dominant noise levels [43] and, therefore, these are not part of the article's scope. capacitor, forming a notch filter.…”

“…For this purpose, 4 series-connected capacitors of 9.4 nF, giving a total capacitance of 2.35 nF, were implemented. Taking all three phases of the AML and the LISNs into account, a simple CM model [43], as depicted in Fig. 13(b), can be obtained.…”