Cascaded Inverters for electric vehicles: Towards a better management of traction chain from the battery to the motor?

Abstract

Currently small electric vehicles (EV) are generally implemented with low voltage batteries around 48V with high current in order to reach a power of several kW for the traction chain. The objective of future converters is to increase the AC amplitude to higher levels (up to 300V) in order to decrease the level of currents, while keeping the same transferred power. Voltage source inverters are generally used in order to drive electric motors. Multilevel voltage source inverters, namely cascaded H-bridge, are under investigation in this paper, in their application to electrical vehicles. This paper presents a numerical and experimental analysis of cascaded H-bridge inverters, and focuses on an optimal modulation strategy. The expected benefits of cascaded inverters for electric vehicle are a better management of battery cells, improved output voltage waveforms, spread thermal losses sources and a better operation in fault modes.