Modulation Strategy Impact of BEV Inverters on the Voltage Ripple and the High-Voltage Traction System Stability

Modulation strategies of traction inverters have a high impact on the efficiency and voltage utilization of the electric drivetrain. An often underestimated effect that comes along with various modulation strategies is their diverging impact on the resulting voltage ripple within the High-Voltage (HV) traction system. The voltage ripple in the first place, but also the DC-side current ripple can be considered as the stability criteria of a HV traction system, which depend upon the DC-link current and the HV system impedance. Since the voltage ripple is the main DC-link capacitance design requirement, the DC-link current harmonics of each modulation strategy have to be analyzed in detail as well as their application range within the torque-speed diagram of an electric drive. The target is to design an ideal DC-link capacitance for each inverter within an electric platform. Therefore, we will discuss the challenge of combining the voltage ripple requirement of different modulation strategies with various HV traction systems.