Operational and energetical effectiveness of road electric and hybrid propulsion

Fiat Research Center is developing, since several years, activities on electric and hybrid apparatuses. These has been applied on vehicles manufactured either for experimental or for pratical operation purposes. The development has been performed with particular consideration to energetical effectiveness, driving response and maintenance requirements, taking into account the economical aspect. The efficiency is achieved both through the drive system concept and the energy management strategy. The drive system for present applications are based on separately excited d.c. motors fed by electronic power conditioners. The particular features of the traction motors and the controllers with the possible diversified version for various applications are discussed in the paper. In the field of future technology, the approach with permanent magnets has been considered. Results on a permanent magnet d.c. motor are presented. The system development and integration as well as the control strategy is explained with reference to the Fiat 900E/E2 and the Iveco Daily E2 electric vans, having a payload of 1/2 ton and 1 ton respectively. The energy consumption of these vehicles measured at the mains is some 160 Wh/ton in urban operation. The operational aspect is discussed referred to driving response and maintenance. In the field of hybrids, the propulsion apparatus and the energy control strategy is described for a hybrid electric bus, developed in a program supported by the Italian National Research Council. It consists of a diesel electric generator unit, storage batteries and a separately excited d.c. motor with electronic controller. The system optimization strategy allowed an improvement of fuel economy in hybrid mode operation in urban areas in terms of 27% in comparison with the conventional version of the bus operating in the same conditions of payload and driving pattern.