Technological and commercial development of vehicles specifically conceived for urban use would certainly be a crucial aspect in making mobility sustainable in urban contexts thanks to their limited in size and low fuel consumption and emissions. Hybrid drive trains are particularly suited to this purpose: if properly designed, very small-sized thermal engines can give all the energy and power required for the application, also making pure electric driving possible when required. The authors are involved since a decade in proposing new low-cost solutions to address this market sector. Market itself explored these possibilities and nowadays offers some BEV solutions in this market share, but it is still lacking in proposing solutions for a parallel full hybrid drive. The main reason must be searched in the complexity of normally applied parallel-hybrid propulsion systems which is not compatible with the limited costs of the application.
Taking the lead from these considerations, the authors here propose a simple concept for a parallel-hybrid kit for quadricycles called Hybrid Power Pack (HPP) which is now installed and under long-range testing on a running vehicle and is available for full characterization and optimization. The HPP was used to equip a small city car to obtain a low-price parallel-hybrid propulsion system concept. The HPP is fully described in the paper and a model of its main parts is presented, devoted to HPP control design. The model was calibrated on the application and its effectiveness was demonstrated through a proper experimental activity.
Results show that the most promising configuration is that with the EM mounted on the secondary shaft of the centrifugal CVT controlled with a Discrete State machine algorithm. This configuration is now under construction at the ENEA labs: experimental results on vehicle running in real condition will be presented soon.