Oliver Bohlen

Impedance based battery diagnosis for automotive applications

In this paper, a procedure is presented, which determines and predicts the pulse power capability of a battery by means of an impedance-based model. This is achieved by a passive impedance measurement technique, which allows using current ripple and fluctuations as a signal source. The advantage of the procedure is its direct determination of the pulse power capability while no indirect and difficult to determine state variables such as state of charge and state of health are needed.

Optimized energy management for fuelcell-supercap hybrid electric vehicles

Combining a fuel cell (FC) as primary power source with a supercap (SC) as a buffer for high power demands is a promising approach for future hybrid electric vehicles (HEV). The objective of an energy management is to minimize the hydrogen consumption and to assure power availability at any time. A simulation environment incorporating models of the FC and SC stacks and the kinetic state of the vehicle allow the detailed analysis and comparison of control strategies. Control strategies that operate the fuel cell most efficiently and take best advantage of the supercap can save more than 20% hydrogen fuel.