Download Inverters

Inverters
Alex Stanton
Henry Schober III
Benjamin Garber
Rance
What is an Inverter?
An inverter is an
electrical circuit
capable of turning DC
power into AC power,
while at the same
time regulating the
voltage, current, and
frequency of the
signal
Why do I need an inverter?
Most solar panels provide 12V DC power
Household devices use 120V AC power
Necessary for a grid tie in system
What kind of inverter do I want?
Inverters come in all different shapes and
sizes, for all different purposes
Inverters vary in output from 50 – 5,000 W
Several different methods of changing DC
power to AC power
Some inverters put out electricity of higher
‘quality’ than others. What does that
mean?
Electrical wave forms
Graphs of voltage as a function of time
Power that comes
from a PV panel or
battery is
generally 12V DC
Power
Different types of
inverters give
outputs with
different wave
forms
12V DC Power
Square Wave
Modified Sine Wave
True Sine Wave
Different types of inverter output
Square wave inverters are basically
obsolete
Modified sine wave output will power
almost everything in your house.
However, things like power drills, or
battery chargers may not work
True sine wave output is exactly the same
as the power provided by a utility
company, and is necessary for a grid intertie system
Methods of inversion
Rotary inverters use a DC
motor to turn an AC
Power generator, the
provide a true sine wave
output, but are inefficient,
and have a low surge
capacity rating
Electrical inverters use a
combination of ‘chopping’
circuits and transformers
to change DC power into
AC. They are much more
widely used and are far
more efficient and
practical. Less expensive
electrical inverters
produce a modified sine
wave, while more
expensive models give a
true sine wave.
How do they work?
There are 2 types of electrical inverters, the first takes
low voltage high current power from a PV panel or
battery and sends it through a ‘chopping’ circuit which
changes it to low voltage high current AC power at
60Hz. The power then goes through a series of large
transformers which output 120V AC power at 60Hz
How do they work?
The second type of electrical inverter is more complex. Two chopping
circuits are employed to make it possible for a much smaller and
lighter transformer to be used. The DC power is converted to very
high frequency AC power which is easier to transform into high
voltage low current power. The power is then rectified back into DC
power and sent through a second chopping circuit to turn it into 60Hz
120V AC.
How are Inverters rated?
Continuous output rating: The maximum
wattage that the inverter can support long term,
includes all everyday appliances, lights and
anything else that consumes power.
Surge capacity rating: The maximum wattage
that cam be supported at any given time.
Important when starting devices like refrigerators
or water pumps which require more wattage to
start then to run.
Applications of Inverters
Inverters are used for many practical
purposes
Small inverters can plug into your car
cigarette lighter
Large inverters can be used in a solar or
wind powered home