DC-DC converters are essential in variety of applications including
power supplies such as personal/ laptop computers, cellular phones,
office equipments, spacecraft power systems, and telecommunication
equipments, as well as solar systems where input/output voltage ranges
overlap.
DC-DC converters with step-up/step-down characteristic are required
to produce a regulated output voltage from the solar panel, by storing
the input energy temporarily and then releasing that energy to the
output at a different voltage. The storage may be in either magnetic
field and/or electric field storage components (Inductor/Capacitor).
This conversion method is more power efficient (88.20% to 96.55%)
than linear voltage regulation(about 85%) which dissipates unwanted
power as heat. This efficiency is beneficial to increasing the running
time of battery operated devices. High efficiency is invariably required,
since cooling of inefficient power converters is difficult and expensive,
which can be increased by the use of power MOSFETs, which are able to
switch at high frequency with minimum switching losses and require
a more simplex drive circuit. Another important consideration in DCDC
converters is the use of synchronous switching which replaces the
flywheel diode with a power MOSFET with low “On” resistance, thereby
reducing switching losses. This is achieved using PWM switched mode
control design or pulse width modulation, PWM allows control and regulation
of the total output voltage.
In this work the concept of DC/DC buck-boost converter is studied to
build the PWM+MPPT charge controller to achieve the better efficiency
and battery protection compare to existing linear charge controller and
MPPT charge controller.