Design of alternative energy storage systems for hybrid vehicles based on statistical processing of driving cycles information

Hybrid vehicles represent the future for automakers, since they allow to improve the fuel economy and to reduce the pollutant emissions. A key component of the hybrid powertrain is the Energy Storage System, that determines the ability of the vehicle to store and reuse energy. Though electrified Energy Storage Systems (ESS), based on batteries and ultracapacitors, are a proven technology, Alternative Energy Storage Systems (AESS), based on mechanical, hydraulic and pneumatic devices, are gaining interest because they give the possibility of realizing low-cost mild-hybrid vehicles. Currently, most literature of design methodologies focuses on electric ESS, which are not suitable for AESS design. In this contest, The Ohio State University has developed an Alternative Energy Storage System design methodology. This work focuses on the development of driving cycle analysis methodology that is a key component of Alternative Energy Storage System design procedure. The proposed methodology is based on a statistical approach to analyzing driving schedules that represent the vehicle typical use. Driving data are broken up into power events sequence, namely traction and braking events, and for each of them, energy-related and dynamic metrics are calculated. By means of a clustering process and statistical synthesis methods, statistically-relevant metrics are determined. These metrics define cycle representative braking events. By using these events as inputs for the Alternative Energy Storage System design methodology, different system designs are obtained. Each of them is characterized by attributes, namely system volume and weight. In the last part the work, the designs are evaluated in simulation by introducing and calculating a metric related to the energy conversion efficiency. Finally, the designs are compared accounting for attributes and efficiency values. In order to automate the driving data extraction and synthesis process, a specific script Matlab based has been developed. Results show that the driving cycle analysis methodology, based on the statistical approach, allows to extract and synthesize cycle representative data. The designs based on cycle statistically-relevant metrics are properly sized and have satisfying efficiency values with respect to the expectations. An exception is the design based on the cycle worst-case scenario, corresponding to same approach adopted by the conventional electric ESS design methodologies. In this case, a heavy system with poor efficiency is produced. The proposed new methodology seems to be a valid and consistent support for Alternative Energy Storage System design.

Magnetic actuators for nanosatellite attitude control

The research and the activities presented in the following thesis report have been led at the California Polytechnic State University (US) under the supervision of Prof. Jordi Puig Suari. The objective of the research has been the study of magnetic actuators for nanosatellite attitude control, called magnetorquer. Theese actuators are generally divided in three different kinds: air core torquer, embedded coil and torquerod. In a first phase of the activity, each technology has been analyzed, defining advantages and disadvantages, determining manufacturing procedures and creating mathematical model and designing equation. Dimensioning tools have been then implemented in numerical software to create an instrument that permits to determine the optimal configuration for defined requirements and constraints. In a second phase of the activities the models created have been validated exploiting prototypes and proper instruments for measurements. The instruments and the material exploited for experiments and prototyping have been provided by the PolySat and CubeSat laboratories. The results obtained led to the definition of a complete designing tool and procedure for nanosatellite magnetic actuators, introducing a cost analysis for each kind of solution. The models and the tools have been maintained fully parametric in order to offer a universal re-scalable instrument for satellite of different dimension class.

Real Driving Emissions: analisi e sperimentazione di metodologie di selezione dei percorsi su strada e di definizione di cicli di laboratorio

La presente tesi si occupa di identificare la metodologia utilizzata per la definizione di percorsi Real Driving Emissions. Nel particolare sono stati individuati due percorsi, uno in piano, definite RDE Moderate Track ed uno in quota, definito RDE Extended Track. Si è anche eseguita una analisi dei cicli su banco a rulli NEDC e WLTC in ottica Real Driving Emissions.