Modular multilevel inverter: A study for automotive applications

This paper describes possible incorporation of a modular multilevel inverter (MMI) for a low voltage low-medium power electric vehicle drive. The main focus of this work is essentially to justify the MMI topology as a viable alternative to the classical 2-level voltage source inverter in an electric vehicle drive due to its highly efficient operation. MMIs are viable alternatives for use in low and medium power applications due to lower power dissipations in the switches, low harmonic contents, modularity and outputs with lower electromagnetic interference (EMI). The MMI discussed is based on the half-bridge topology. The modes of operation and different control features have been reviewed. The capacitive voltage unbalance phenomenon is discussed and few balancing techniques are reviewed. Different PWM techniques and switch utilization of the half-bridge topology are also reviewed. A comparative study of two level VSI and 3, 5 level MMI is discussed in the context of conduction and switching loss reduction.