Showing papers by "Giorgio Rizzoni published in 2021"

Model-based state of health estimation of a lead-acid battery using step-response and emulated in-situ vehicle data

Abstract: Lead-acid (PbA) batteries are one the most prevalent battery chemistries in low voltage automotive applications. In this work, we have developed an equivalent circuit model (ECM) of a 12V PbA battery while preserving the major dynamics of a semi-empirical model we have developed previously. Thereafter, two batteries are aged according to a modified IEC 60095-1 standard and the evolution of ECM parameters investigated. The trend derived from these aging campaigns are used to determine the state of health (SOH) of three either new or aged on the vehicle batteries. The contribution from this approach stems from the fact that the ECM model while being simple is capable of approximating the sum of charge transfer resistances of both electrodes from a short step response. In addition, another SOH estimation technique is developed based on frequency response analysis of a metric dubbed instantaneous dynamic resistance derived from voltage response of the battery during engine cranking. Real world voltage response of the battery during cranking is imitated in the lab and superposed on IEC 60095-1 standard profile, according to which another battery is aged. This data is used to assess the performance of SOH estimation technique.

Collision Avoidance with Transitional Drift Control

Abstract: Enhancing driving safety is a continuing effort towards safer transportation in the automotive industry. It is generally accepted that one of the benefits brought about by increasing levels of automation in vehicles is increased safety. In this paper we propose an automated emergency maneuver controller for safely and stably operating the vehicle at its handling limit in emergency situations. This paper explores the possible scenarios where such an ability is critical to keep an autonomous vehicle safe in an emergency scenario, by implementing a mode switching control design that successfully enhances safety in a driving scenario that would have caused an accident had the vehicle been operated by traditional vehicle control algorithms. The proposed mode switching control design uses geometric and kinematic criteria to determine the mode of operation for a vehicle, and applies tailored optimal control in each mode to minimize the safety risk in a finite planning horizon. The proposed method outperforms two control baselines including a drift sustaining controller in simulation by having the additional flexibility in following a challenging direction-changing path at considerable speed.

Cost analysis in different battery pack architectures considering protection, monitoring, and diagnostics

Abstract: The automotive, aerospace, and electric power systems industry make increasing use of complex energy storage systems that are comprised of large number of cells connected in various electrical configurations. After defining the cell technology and size in terms of voltage and capacity, the objective of the battery pack design includes the definition of cell arrangement, sensing topology and position, fault diagnostic capability, cooling system, and electronic hardware. These design parameters may change with different battery pack architectures. On the premise of ensuring the availability and reliability of a battery system, minimizing the cost is also one of the important design missions. This paper analyzes the property of different battery pack architectures and studies the current distribution among the cells due to parameter variation, which determines the types, amount and unit cost of devices needed for the purpose of protection, monitoring and diagnostics. Finally, a comparative cost analysis of devices between different battery pack architectures as the size of the battery pack varies is presented.