Edgar Tournon defends his PhD on Dec. 10, 2020 at 10:00 AM.
Place : visio conference only
Jury :
Rapporteurs : CHRENKO Daniela (Femto ST), HOANG Emmanuel (Satie)
Membres : BARBEDETTE Bertrand (S2ET), CHEZE Laurence (LBMC), EL GHOSSEIN Nagham (ECAM), VINASSA Jean-Michel (IMS)
Encadrement : SARI Ali, VENET Pascal (Ampère)
Invités : M. AUBRY Judicael (IUT de Rennes), PELISSIER Serge (UGE)
Abstract :
This thesis presents, analyses and solves several scientific problems related to the hybrid series
bicycle.
Initially introduced in the car industry, this architecture type features a lOO% electrical ( chainless) transmission. This allows the decoupling of user effort from the bicycle dynamics. The transmission is equipped with a generator subsystem that converts the user’s mechanical power into electricity as well as a motor subsystem that converts electricity back to mechanical power in order to propel the bicycle. In addition, this project foresees the implementation of an energy storage system based on supercapacitors, which are more respectful of the environment than batteries. The challenge was to propose a bicycle with this new storage system that provides the same comfort as e-bikes.
Associating supercapacitors with a hybrid series structure for light mobility purposes is an original approach. It raises several scientific problems that are discussed in this work. Firstly, the use of a supercapacitor as the main energy source was analysed, considering the small embedded energy amount stored compared to batteries. A mult icriteria approach was used and aging tests were carried out in order to determine the relative lifespan of batteries and supercapacitors for an energy equivalent usage.
Secondly, the hybrid series architecture was modelled and analysed. Indeed, energy is transferred through several energy conversions, and losses occur at each stage. If energy losses are too significant, the system may not be able to work correctly. Therefore, simulations were undertaken in order to compare the travel capacity of both the normal bicycle and hybrid series bicycle, taking into account the efficiency of both architectural types. Minimum efficiency requirements could be extracted from the results. Finally, a more detailed efficiency computation was undertaken using component databases in order to validate the feasibility of the desired
efficiency.
The management of energy within the hybrid series architecture was then examined. The hybrid series architecture decouples input and output effort and therefore offers a degree of freedom to the system. This degree needs to be controlled in order to run the bicycle. A control strategy was established by reproducing optimal control solutions using fuzzy logic tools. Simulation results were found. Practical tests were undertaken on a homemade laboratory test bench. The results pave the way for further testing and energy management strategies.
Finally, the impact of cycling on a hybrid structure was analysed. Two major topics are discussed. The first concerns pedalling effort and the associated user movement, which may be uncomfortable due to very low generator inertia. The second consists in proposing a model and measurements concerning cyclist effort and fatigue on a hybrid bicycle compared to the t raditional bicycle. On the basis of these analyses, this thesis provides conclusions on the advantages of decoupling for the cyclist.
Key Words : Bicycle, hybrid, series hybrid, batteries, supercapacitors, energy storage system aging, modelling, electrical machines, DCDC and ACDC converts, simulation, optimal seek, bi-objective, data base, energy management, online real-time programming, test bench, fatigue, user stress, cycling dynamics, prototypes
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