Interference of automotive HV-DC-systems by traction voltage-source-inverters (VSI)

This paper presents a method to analyze and quantify the interference of an automotive HV-DC-system due to excitation currents emitted by the voltage-source-inverters. This process is explained by reference to an exemplary HV- system of a battery electric vehicle. As a part of this research, the HV-system's modelling, a strategy for its parametrization as well as a metrological verification, based on impedance comparison is exposed. The HV-system's impedance information is sufficient for validation. However, it does not allow to identify potentially dangerous excitation frequencies. Hence, an instrument in order to make possibly critical points of HV-system transparent is introduced. This instrument is the weak-point analysis which is based on current ratio transfer functions, generated by a state space model that describes the HV-system. As a result, component specific critical excitation frequencies are deduced and again metrologically validated. Furthermore, results from a previous publication are taken into account and combined with the critical frequencies, obtained later in this research. Finally, operating points of traction inverters, electric engines and therefore of the vehicle are determined which might be individually critical for each HV- system's components. Comprising, this paper offers a common thread on how to avoid damages to the HV-system's components. This is achieved by influencing the dimensioning as well as by the definition of worst case operating points for an already existing system.