Bernhard Kortschak

Simulation Study on Dual-Cell Battery Power Management for PHEV Application

Abstract In order to address the issue of higher requirements on battery systems in Plug-in Hybrid Electric Vehicles (PHEV), this paper carries out a simulation on the energy distribution strategy of a dual-cell Li-Ion battery system. The dual-cell battery consists of high-energy and high-power cells. The paper establishes a platform for co-simulation based on AVL Cruise and Simulink, proposes a rule-based energy distribution strategy, and conducts simulations and evaluations on selected driving cycle. Results demonstrate that the strategy can well take the advantages of both high power cells and high energy cells, such that the energy cells are utilized over a wider State-of-Charge range providing a better overall energy density and stress like peak charging is limited, which will improve the lifetime.

Detection method of battery cell degradation

This paper introduces a method, which precisely estimates deviations in the State-of-Charge and resistance values of the cells in a battery pack. The aim of the algorithm is to provide the required information a) for an early detection of cell failures and b) to decide, which cells must be charged or discharged by the charge equalization circuit. The problem is formulated as an inverse problem because the cell resistance values can not be estimated during operation modes of zero or constant battery current and a regularization term ensures that the estimation problem is stable. The paper will present test results from a battery pack, where the algorithm has been implemented in a Battery Control Unit.