Environmental Engineering Reference
In-Depth Information
Eciency of HEH Boost Converter with Fixed Voltage Reference-Based MPPT
100
80
380 lux, ΔT5 K
380 lux, ΔT7 K
380 lux, ΔT10 K
425 lux, ΔT5 K
425 lux, ΔT7 K
425 lux, ΔT10 K
640 lux, ΔT5 K
640 lux, ΔT7 K
640 lux, ΔT10 K
1010 lux, ΔT5 K
1010 lux, ΔT7 K
1010 lux, ΔT10 K
60
40
20
5
0
100
10
150
200
250
7
300
350
5
FIGURE 5.30
Efficiency of HEH boost converter.
computed results are plotted in
Figure 5.30
. It can be observed from
Figure
5.30
that the efficiency of the designed boost converter ranged between 80%
and 94% over a range of load resistances of 50 to 330 k
.Atheavy load con-
dition, say 50 k
, which signifies the discharge state of the supercapacitor, it
can be seen in
Figure 5.30
that the efficiency of the boost converter was high,
around 94%. This high-efficiency boost converter is very favourable and de-
sirable to ensure optimal transfer of energy from the micropower sources of
hundreds of microwatts or even less to the energy storage.
As the loadings lessen with the supercapacitor charge's increase, with refer-
ence to
Figure 5.30
, it can be seen that the efficiency of the converter decreases
to around 82% at a load resistance of 300 k
. This decreasing efficiency trend
is due to the power loss in the boost converter. Even though the efficiency at
light load is lower, it is not as critical as the heavy load condition because the
supercapacitor, by then, is already near the full charge state, and any surplus
energy would not be stored. Another source of power loss in the HEH system
is the power consumption of the associated sensing
P
sense
control,
P
ctrl
, and
PWM generation
P
generate
electronic circuits. Based on the voltage and cur-
rent requirements of each individual component in the HEH system shown
in
Figure 5.28
, the total power consumption of the electronic circuits can be
calculated as follows:
P
consumed
=
P
sense
+
P
ctrl
+
P
PWM generate
=
2
.
7
V
∗
(3
+
15
+
32
A)
=
135
W
(5.13)
Once all the power losses in the HEH system are identified, including the
power difference factor due to impedance mismatch between two paralleled
energy sources and the power losses in the voltage-regulating and MPPT
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