Performance Evaluation of Two-Level and Three-Level NPC Inverters in Electric Vehicles under Various Drive Cycles and Switching Frequencies

Internal Combustion Engine (ICE) vehicles contribute significantly to environmental pollution, rendering Electric Vehicles (EVs) essential for sustainability. Inverters are an important component of the EV propulsion system, and their design has a big impact on the system's overall efficiency. This study compares the performance of two topologies of the inverters, which are the two-level and three-level Neutral Point Clamped (NPC) inverters. Furthermore, the impact of switching frequency on the inverter's efficiency and Total Harmonic Distortion (THD) was analyzed. The analyses were conducted using MATLAB/Simulink to model the EV propulsion system, including the vehicle body, and PLECS to calculate power losses and efficiency. The inverters were tested under two drive cycles, the Urban Dynamometer Driving Schedule (UDDS) and the Highway Fuel Economy Test (HWFET), to cover torque-speed operating points and provide a comprehensive view of their performance. The results demonstrate that the three-level inverter outperforms the two-level inverter by reducing both power losses and THD, thereby improving the overall efficiency of EVs. These findings suggest that the three-level inverter is a more sustainable option for EVs.