Comparative Analysis of Conducted Emissions between 3-level and 2-level Inverters for Automotive Drives

Automotive drives are considered a major source of electromagnetic interference in the high-voltage system of an electric vehicle. The recent advances in semiconductor technology towards more compact and faster switching devices bring an increasing challenge to meet the stringent electromagnetic compatibility requirements that are applied in the automotive industry. Multilevel inverters have received increasing interest due to their benefits of lower losses and higher voltage capability. Specifically, the three-level inverter shows a good balance between these benefits and low complexity and high technological maturity. However, it is still not widely studied how it performs compared to the standard 2-level counterpart when their radio-frequency emissions are evaluated. This paper presents comparative simulations of conducted emissions at the DC-side of drives with 2-level and 3-level inverters. The electrical machine of the drive system has been modelled utilizing scattering-parameter measurements of a real machine in order to simulate accurately the common-mode current flow. The results showcase over the frequency range of 9 kHz - 100 MHz the benefits of using a 3-level inverter.