Environmental Engineering Reference
In-Depth Information
5.3.6
Summary
A near-optimal HEH system has been proposed for enhanced performance of
an indoor wireless sensor node. Theoretical studies of individual subsystems
as well as hybrid SEH and TEH systems were conducted and simulated to
understand the characteristic of the HEH system, which were then verified
by experimental results. In this section, the proposed HEH system using one
power management circuit was successfully implemented into a hardware
prototype for laboratory testing. Based on the power analysis, the efficiency of
the power management unit with fixed reference voltage-based MPPT scheme
was around 90% and its sensing, control, and PWM generation circuitries
consumed around 135
W. Experimental results showed that the HEH system
can harvest an average electrical power of 621
Wfrom both energy sources
at an average solar irradiance and thermal gradient of 1010 lux and 10 K,
respectively, which is almost 3.3 times higher than the conventional single
thermal energy harvesting method to enhance the performance of the indoor
wireless sensor node.
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