Hybrid Energy Harvesting System - Energy Harvesting Autonomous Sensor Systems - page 142

5.2 Composite Solar, Wind (S+W) Energy Sources
To understand the functionality and performance of the proposed HEH sys-
tem in a better way, the circuit architecture of a wind-cum-solar-powered
wireless sensor node is presented in Figure 5.3 . The HEH wireless sensor
node consists of the WEH and SEH subsystems connected in a parallel con-
figuration so that the harvested electrical power from either wind or solar
energy source, P WEH or P SE H ,respectively, can be used to charge the energy
storage device.
A similar HEH research work was discussed by Park et al. [35], Ambi-
Max, which harvests simultaneously from two energy sources to sustain the
operation of the sensor nodes. Each energy source is allocated to charge its
own supercapacitor, and the energy stored in these supercapacitors is then
transferred to the lithium ion battery. Although simultaneous charging from
two energy sources can be achieved, the drawback is that the physical size of
AmbiMax becomes too large, bulky, and heavy as compared to a miniaturized
wireless sensor node.
This chapter discusses the use of one energy storage device for simulta-
neous charging from two energy sources and to develop a miniaturized HEH
system for portability and concealment in security applications [138]. Among
the commonly available renewable energy sources, solar and wind are the

Wind Energy Harvesting (WEH) Subsystem Diode Block

I WEH

AC-DC
Active
MOSFET
Rectifier

v s C in Boost

Converter
with MPPT

+ Wireless

Sensor
Node

Z s

D 1

Super
Cap

D 2

V WEH

R sense

-

Wind Turbine-
Generator

Voltage ( V wind )

and Current
( I wind ) Sensing

V wind

I wind

V MPPT ,
wind
V MPPT ,
solar

MPP Tracking
and Controlling

PWM
Generation

V solar

Voltage ( V solar )

I SEH
+

Solar Panel

I L I D

R s,pv Boost

Converter
with MPPT

V SEH

-

Solar Energy Harvesting (SEH) Subsystem

FIGURE 5.3
Functional block diagram of HEH wireless sensor node. (AC-DC, alternating current-
direct current; MOSFET, metal-oxide-semiconductor field-effect transistor; PWM, pulse width
modulation.)