Comparative Analysis of Two-Level and Multilevel CHB Topologies for EV Drivetrain

The climate change and scarcity of fossil fuel resources has resulted in the shift of automotive industry towards an environment friendly and sustainable solution, i.e. electric vehicle (EV). The DC-AC inverter is one of the main building blocks of EV power train. Selection of an appropriate inverter topology leads to optimal performance, cost effectiveness and reliable operation of the whole power train. This paper compares four inverter topologies for EV applications, including the widely used two-level inverter (TLI) based on IGBTs, technologically advanced SiC MOSFET based TLI, and five and seven-level Cascaded H-Bridge (CHB) inverters. While IGBT -based TLIs are simple, cost-effective, and easy to control, they suffer from high harmonic distortion and losses. Recent research has focused on using SiC MOSFETs in TLIs to improve power density and efficiency. CHB inverters have also emerged as a promising alternative to TLIs, offering better power quality, lower voltage stress, scalability, and fault tolerance capabilities. The comparison in this work is based on losses, cost, and thermal analysis using PLECS software for simulations. Based on the results, it is concluded that the CHB five-level inverter topology is a superior choice for EV powertrains, offering better thermal behavior, reduced total harmonic distortion (THD), and lower losses.