Environmental Engineering Reference
In-Depth Information
Performance Comparison between TEH without MPPT and with
MPPT Plus Associated Losses
2500
TEH without MPPT
TEH with MPPT
Power loss in buck converter
Power loss in associated circuitry
2000
1500
1000
500
0
DT15
DT20
Te m p erature Differences (K)
DT25
DT30
FIGURE 3.16
Performance comparison between the TEH system without MPPT and with MPPT.
the net harvested power from the TEH system with the MPPT scheme is
still more than the case without the MPPT scheme. Hence, this exhibits the
importance as well as the contribution of implementing MPPT in the TEH
system.
3.5 Summary
In this chapter, an efficient TEH system and its power management circuit
have been proposed to maximize power transfer from the heat source to
its connected wireless sensor node. The electrical characteristic of the TEH
system is unlike the case of the other common energy harvesting sources like
solar and vibration, where most of the conventional MPPT approaches with
very little control overhead are not suitable. This chapter presented a resistor
emulation-based MPPT technique to emulate the load impedance to match
the impedance of the TEH system. Experimental results showed that the self-
autonomous wireless sensor node powered by the designed TEH system and
its ultralow-power and efficient power management circuit yielded better
performance than the conventional battery-operated wireless sensor node. At
a temperature difference of 20 K, the efficiency of the buck converter was 92%,
and its associated power management circuit consumed 289
Wofpower to
operate. From the experimental test results obtained, an average electrical
power of 629
W was harvested by the optimized TEH system at an average
temperature difference of 20 K, which is almost two times higher than the
conventional energy harvesting method without using MPPT.
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