Improvement of Electric Vehicles Performance using Energy Storage Systems with High Specific Power

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Electrified powertrain systems have gained a significant interest to develop energy-efficient Electric Vehicles (EVs). Energy Storage System (ESS) is central to reach higher driving range, better climbing or acceleration capabilities, and increased energy efficiency. Currently, batteries are widely-used in EVs, but to obtain an acceptable driving range, batteries with High Specific Energy (HSE) are typically preferred but their specific power is normally low (~1kW/kg). Recent trends suggest that new battery systems with promising potential as Li-Ion capacitor or SuperCapacitors (SCs) have been developed to give High Specific Power (HSP) (~12kW/kg). These systems could address part of the fast degradation of the main energy battery when coupled together, and increase the driving range by storing the braking energy more efficiently. Their control is a double challenge because it demands a high performance converters and an intelligent management. The long-term vision of my research is to develop performant, reliable and cost-effective energy conversion and ESSs for transport that will reduce overall fossil fuel consumption. Since 2008, my research has focused on the real time power sharing strategies for a multi-ESS EVs (battery and SCs) for increasing the global performance at the end of the driving cycle. In parallel, I have studied the Variable Inductor (VI) concept to solve the saturation issues of power inductors for high power transfers showing a considerable reduction of magnetic material, with better efficiency and power density.***As an enhancement of the aforementioned research, the general objective of this Discovery Grant (DG) is to demonstrate that HSP-ESSs coupled through improved VI-based power converters, correctly coordinated by an intelligent multi-objective energy management algorithm, may increase the global efficiency and the driving performance of EVs. To achieve this goal, under an extended interdisciplinary challenge, I will pursue the following 3 specific objectives: 1) to analyze the energy efficiency of HSP-ESS, with the specific usage of VI-based converters, including theirs design and implementation; 2) to study the impact on the main ESS performance with the addition of the HSP-ESSs, using a new defined indicator of merits; 3) to develop algorithms encompassing multiple objective functions to which different degrees of importance are assigned as a function of some exogenous variables (traffic, user requirements, weather conditions, etc.), to address the random nature of the power demand of the driving cycle.***The novelty of the proposed approach is to use the VI concept in order: 1) to develop more efficient, smaller and lighter DC/DC converters; and 2) to define multi-objective algorithms to better integrate the HSP-ESSs into the EV to address simultaneously two main challenges: the energy management of multi-ESS and the control complexity of the VI.