Environmental Engineering Reference
In-Depth Information
I
in
I
out
v
l
V
out
V
in
Figure 4.36
Step-down DC-DC Converter (also known as a series switching regulator or buck
converter)
I
in
I
out
v
l
V
out
V
in
Figure 4.37
Step - up DC - DC converter (also known as a boost converter)
Step - up DC - DC Converter
Provided that the current in the inductor is continuous the steady state operation of the circuit
in Figure 4.37 is given by
1
(4.31)
V
=
D
V
out
in
1
−
4.6 Applications to Renewable Energy Generators
4.6.1 Applications to PV Systems
PV System Characteristics
All PV systems generate direct current and so power electronic converters, known as invert-
ers, are required to connect them to power systems.
As described in Chapter 2, PV modules have an
I - V
characteristic that depends on incident
radiation intensity (and to a lesser extent the solar spectrum) and module temperature. Dif-
ferent types of PV have different shapes of
I - V
curve, characterized in simple terms by a fi ll
factor, as explained in Chapter 2. To maximise the output of any PV module, or collection
of modules, operation should be at the maximum power point. This point will change with
radiation and temperature and a key function of the inverter is to track this. How effective
this so-called maximum power point tracking (MPPT) is can critically affect the overall effi -
ciency of the PV system.
