Search Results

A test center for aging analysis and characterization of Lithium-Ion batteries for automotive applications is optimized by means of a dedicated cell tester. The new power tester offers high current magnitude with fast rise time in order to generate arbitrary charge and discharge waveforms, which are identical to real power net signals in vehicles. Upcoming hybrid and electrical cars show fast current transients due to the implemented power electronics like inverter or DC/DC converter. The various test procedures consider single and coupled effects from current profile, state of charge and temperature. They are simultaneously applied on several cells in order to derive statistical significance. Comprehensive safely functions on both the hardware and the software level ensure proper operation of the complex system.

Hybrid vehicles are becoming more and more attractive due to their reduced emissions and their higher fuel efficiency. Storage of electrical energy is the most critical aspect of hybrid automobiles. Therefore, an exact knowledge of the behavior of the battery and further electrical storage elements is mandatory. Their nonlinear characteristics over wide ranges of current magnitude, transient period, temperature and state of charge must be evaluated. Battery aging is another matter of increasing importance. For this reason, an automated battery test bench has been developed which is capable of reproducing high dynamic loads in both charging and discharging direction. Pulse rise times are in the range of a few microseconds at maximum currents up to 1500 A. The quasi-static charge and discharge power can reach 20 kW. Optimized characterization programs enable a rapid extraction of battery behavior parameters as well as capacitor characteristics.