Modelling, Sizing and Control of Hybrid Energy Storage Systems for Electric Vehicles

Modelling, sizing and control of a Hybrid Energy Storage System (HESS) made up of Batteries (B) and Supercapacitors (S) is presented in this paper. The HESS is characterized by an integrated topology through a Three-level Neutral-Point Clamped Converter (NPC), leading to a highly-integrated electric propulsion system. Accurate modelling of both B and S are considered at first, although some simplifications are introduced due to automotive application. Then, a suitable sizing procedure is introduced and discussed in detail, which is based also on an experimental S characterization. The HESS control approach is described as well, which is quite robust against the non-linear model of S due to the integrated topology. The effectiveness of all the design solutions has been validated through a simulation study, which refers to a vehicle start and stop.