Limitations of established vehicle modelling approaches for the conceptual design of hybrid special-purpose vehicles

A lot of the literature reporting on the design of hybrid electric vehicles is motivated by the possibility to increase the overall driving efficiency. Different vehicle simulation tools have been developed. They are primarily used for analysis, optimisation and benchmarking of different drivetrain topologies and components concerning this criterion. If hybrid drivetrain layouts for special-purpose vehicles (SPVs) are to be investigated, the aim is not necessarily an optimised efficiency. Furthermore, there may also be fundamentally different governing requirements and constraints compared with passenger cars or busses. This paper addresses important differences and several critical aspects that need to be considered when investigating the electric hybridisation of SPVs. It furthermore intends to raise awareness of the limitations of frequently used vehicle simulations, at least during earlier design stages when the primary concerns are the identification of suitable drivetrain topologies, the preselection of required components and first estimates of their desired characteristics.