Management of the Output Electrical Power in Thermoelectric Generators

Abstract

Thermoelectric Generators (TEGs) are devices for direct conversion of heat into electrical power and bear a great potential for applications in energy scavenging and green energy harvesting. Given a heat source, the conversion efficiency depends on the available temperature difference, and must be maximized for optimal operation of the TEG. In this frame, the choice of materials with high thermoelectric properties should be accompanied by the identification of criteria for an optimal exploitation of the electrical power output. In this work, we briefly review the main properties of TEGs, focusing on the electrical power output and the thermal-to-electrical conversion efficiency. Besides, we discuss principles of operation of TEGs enabling the optimization of the electrical power output, based on the suitable choice of the electrical load. In particular, we comparatively present and discuss the conditions for matching the electrical load—yielding to maximum power transfer—and those for maximizing the conversion efficiency. We compare the two conditions applying them to the exploitation of a heat reservoir for energy storage and to the recovery of heat from a heat exchanger. We conclude that the difference between the two conditions is not significant enough to justify the complexity required by the implementation of the maximum efficiency. In addition, we consider the effect of the thermal contact resistance on the electrical power output. Using a simple thermal-electrical model, we demonstrate that the equivalent electrical resistance measured between the terminals of the TEG depends on the thermal exchange. Hence, for maximum power transfer, the electrical load of the TEG should not match its parasitic resistance, but the equivalent electrical resistance in each specific operating conditions, which determine the thermal fluxes. The model can be applied for the development of efficient alternative algorithms for maximum power point tracking.

Low‐powerFinFETbased boost converter design using dynamic threshold body biasing technique

“…Figure 8 illustrates performance of proposed DC–DC boost converter with . It can be noticed from Figure 8a that the proposed DTFinFET based DC–DC boost converter shows higher value of than DC–DC boost converter designed without using DTFinFET based technique upto of 150 mV which is the actual voltage range (tens of millivolts to few hundreds of millivolts) delivered by the TEGs 3,6,18–21 . At higher input voltages (>150 mV), the output voltage of DTFinFET based DC–DC boost converter is slightly lower than that of DC–DC boost converter designed without using DTFinFET technique.…”

“…The design of LC oscillator is characterized by external off‐chip inductors and to obtain the optimized clock frequency. This setup is assumed to be powered with a harvested input source of 96 mV owing the fact that thermo‐electric generators generate low voltage ranging from tens of millivolts to few hundreds of millivolts (the available output power from TEGs) 3,6,18–21 …”

“…Among these, the thermo‐electric generators which can convert thermal energy into voltage are suitable candidates for wearable electronics. However, thermo‐electric generators generate low voltage ranging from tens of millivolts to few hundreds of millivolts which is not enough to meet the standard load limits 3,6,18–21 . This limitation of energy harvesting sources has prompted the researchers to boost the low voltage to usable higher voltage 13,22 .…”

Semaver ile Entegre Termovoltaik Gerilim Kaynağı

“…For example, truck exhausts are also equipped with thermovoltaic cells to obtain extra electrical power for a truck power system [12]. They require a maximum power tracking system [13]. New application areas for thermovoltaic cells are sought [5][6][7][8].…”

A Subthreshold Cross-Coupled Hybrid Charge Pump for 50-mV Cold-Start

“…Limited by the device size and the accounted temperature difference (e.g. that between the human skin and the ambient air ranging from 2°C to 5°C on average) the voltage generated by TEGs in practical application scenarios results to be often as low as several tens or a few hundreds of milli-volts [12]- [15]. Moreover, to extract the maximum power from the TEG, its output voltage must be set to half of its open circuit value.…”