Modeling and optimization of energy harvesting-systems under non-ideal operating temperatures with regard to availability of power-supply and reduction of environmental impacts

The interest in micro systems integrating own power conversion units using energy from the surrounding environment is steadily growing. Main application fields can be found in industry because of the chance to save significant maintenance costs due to extended system lifetime without the need to change batteries on a regular basis. Moreover, reduction of battery use in wireless application is desired from an environmental point of view. Recent studies at Technical University of Berlin and Fraunhofer IZM focus on the design of condition monitoring systems for industrial applications. Within the frame of the project `ECoMoS' (Energy-autarkic condition monitoring system) a sensor network of self-sufficient micro systems is currently developed for condition monitoring purposes of machine parts in paper plants. Focus of this paper is the development of a system-oriented model of the energy conversion chain. Optimization of energy flows is a prerequisite in order to achieve a high degree of miniaturization and efficient use of materials implemented. The modeling framework proposed in this paper allows simulation of the available power on a modular, expandable basis. The parameterized sub-models allow variation of parameter sets gained from measurements even under non-ideal operation conditions, e.g. elevated temperatures. As thermal gradients provide useful energy sources in industrial environments, e.g. a paper mill, system setup and physical modeling of a thermoelectric converter are described exemplarily. Simulation of energy flows of real load profiles using Matlab/Simulink will be presented. The proposed system setup will then be evaluated by an environmental analysis of the materials contained.