Abstract
Energy harvesting has become a promising and alternative solution to conventional energy generation patterns to overcome the problem of supplying autonomous electrical systems. More particularly, thermal energy harvesting technologies have drawn a major interest in both research and industry. Thermoelectric Generators (TEGs) can be used in two different operating conditions, under constant temperature gradient or constant heat flow. The commonly used TEG electrical model, based on a voltage source in series with an electrical resistance, shows its limitations especially under constant heat flow conditions. Here, the analytical electrical modeling, taking into consideration the internal and contact thermal resistances of a TEG under constant temperature gradient and constant heat flow conditions, is first given. To give further insight into the electrical behavior of a TEG module in different operating conditions, we propose a new and original way of emulating the above analytical expressions with usual electronics components (voltage source, resistors, diode), whose values are determined with the TEG’s parameters. Note that such a TEG emulation is particularly suited when designing the electronic circuitry commonly associated to the TEG, to realize both Maximum Power Point Tracking and output voltage regulation. First, the proposed equivalent electrical circuits are validated through simulation with a SPICE environment in static operating conditions using only one value of either temperature gradient or heat flow. Then, they are also analyzed in dynamic operating conditions where both temperature gradient and heat flow are considered as time-varying functions.
Highlights
In the last decade, many research works have been focused on the design of autonomous systems with capability to operate uninterruptedly
Heat is converted into electricity through a thermoelectric energy harvesting chain composed of a thermoelectric generator (TEG) and an electronic circuitry, whose main role is to extract a maximum of available electric power and to regulate the output voltage
To facilitate the electrical simulation of a TEG under constant heat flow conditions with the thermal contact resistance taken into account, we propose to emulate this load current-dependent resistance
Summary
Many research works have been focused on the design of autonomous systems with capability to operate uninterruptedly. Heat is converted into electricity through a thermoelectric energy harvesting chain composed of a thermoelectric generator (TEG) and an electronic circuitry, whose main role is to extract a maximum of available electric power and to regulate the output voltage. The most used fully electrical model of a TEG in the literature is the commonly used one composed of a constant voltage source α∆T in series with a constant electrical resistance R E , which neglects the thermal resistances θm and θc This same electrical model is used under both constant temperature gradient and constant heat flow operating conditions. The fully electrical models of a thermoelectric generator under different operating conditions which take into consideration all above mentioned parameters are needed.
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