Teemu Lehmuspelto

Time-Domain Parameter Extraction Method for Thévenin-Equivalent Circuit Battery Models

This paper presents an analytical time-domain-based parameter identification method for Thévenin-equivalent circuit-based lithium-ion battery models. The method is based on the analysis of voltage-relaxation characteristics of pulse discharge and pulse charge experiments, and the method can be used for both discharge and charge operation with any number of parallel resistor-capacitor branches. The use of the method is demonstrated for a second-order model and validated with a real-world duty cycle. Experimental results for a commercial lithium-ion battery module are presented.

Electrical battery model for dynamic simulations of hybrid electric vehicles

This paper presents an electrical battery model for lithium-ion (Li-ion) batteries that can be used for dynamic simulations of hybrid electric non-road mobile machinery (NRMM) and other vehicles. Although the model has been developed mainly for large vehicle batteries with Li-ion based chemistries, it can be used for other battery chemistries as well. The parameters can be extracted from simple measurement sets. The model calculates e.g. state-of-charge, terminal voltage, and open-circuit voltage. In this paper, the model structure and parameter extraction are explained in detail, and a model for a 25.9 V lithium-ion polymer battery module with 40 Ah cells is presented. Parameters are extracted from experimental measurements and the model is validated by making another experiment with more realistic hybrid electric NRMM current profile.

Thermal investigation of a battery module for work machines

Thermal Design of Li-ion battery cells/modules is necessary to ensure better cycle lifetime of the batteries. High power batteries (40Ah–100Ah) generate a significant amount of heat which needs to be dissipated somehow. In this work thermal experiments and simulation are utilized for better thermal design of battery module. The results indicate that liquid cooling is almost indispensible for high power battery modules. This methodology also ensures that the waiting period for battery cool down can also be reduced significantly which helps in better and proper utilization of the batteries.

Development and validation of a Li-ion battery pack for non-road mobile machinery applications

Battery is a critical component of an electric vehicle and electric non-road mobile machinery. The performance of a battery system must be assessed by experimental testing to achieve high reliability. This paper describes the development and validation of a battery pack for a mining load-haul-dump loader application. The typical duty cycle is used as a validation power profile.