Environmental Engineering Reference
In-Depth Information
DC-DC Boost Converter
Energy
Storage
V
in
V
out
L
10 mH
+
+
WEH Source
and
AC-DC
Active
MOSFET
Rectifier
DC-DC Buck
Converter
and
Wireless
Sensor Node
Super
Cap
1.5 F
5 V
C
in
220 uF
NMOS
Si1563EDH
PWM
10 Ω
-
-
V
source
) and
Current (
I
source
) Sensing
I
source
Voltage (
V
source
V
mppt
MPP Tracking and
Controlling
PWM Generation
FIGURE 2.13
Overview of a DC-DC boost converter with MPPT.
electronically controlled to sweep through a wide range of values (10 to 800
)
as shown in the power curve (left side) and I-V curve (right side) of
Figure 2.14
.
Based on the fundamental equations of the DC-DC boost converter under
continuous conduction mode (CCM), the emulated resistance at the input
port of the converter is governed by
Equation 2.5
:
D
)
2
R
load
R
em
=
(1
−
(2.5)
is selected to
represent the average power consumption of the wireless sensor load. Since
R
load
is a constant, the input resistance
R
em
of the converter is related to the
duty cycle
D
of the boost converter as expressed in
Equation 2.5
.
As such,
R
em
is manipulated to match with the internal resistance of the wind turbine of
150
Under a static load condition, a fixed resistor
R
load
of 1.2
k
to attain MPPT by controlling the duty cycle
D
of the boost converter's
gating signal.
R
em
R
load
D
=
1
−
(2.6)
Referring to the sweeping process captured in the oscilloscope as shown by
the power curves in
Figure 2.14
, it is observed that all the maximum power
points (MPPs) are centralized around the optimal resistance of 150
for dif-
ferent wind speeds. The experimental results obtained illustrate that using the
designed boost converter circuitry with a resistor emulation MPPT approach,
maximum power is indeed transferred from the wind turbine generator to
the wireless sensor load.
The MPPT performance of the designed boost converter together with its
proposed closed-loop resistance emulator was also tested experimentally un-
der dynamic conditions, that is, changing wind speeds from 2.3 to 6.3 m/s as
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