Transcript Chapter #8 Power Point

PowerPoint® Presentation
Chapter 8
Inverters
AC Power • Inverters • Power
Conditioning Units • Inverter
Features and Specifications
Chapter 8 — Inverters
If voltage and current
signals are either always
positive or always
negative, they are DC
waveforms. If the signals
switch between positive
and negative, they are AC
waveforms.
Chapter 8 — Inverters
AC waveforms can take a
variety of shapes.
Chapter 8 — Inverters
Certain parameters are
integral to defining the
characteristics of an AC
waveform
Chapter 8 — Inverters
Three-phase power is
composed of three
separate voltage waveforms that are 120° out of
phase.
Chapter 8 — Inverters
Voltage variations outside
allowable ranges include
voltage drops, voltage
swells, and transients.
Chapter 8 — Inverters
Three-phase voltage and
current waveforms are
unbalanced if they are not
equal in magnitude and
frequency.
Chapter 8 — Inverters
Harmonics can add to the
fundamental frequency to
produce distorted
waveforms.
Chapter 8 — Inverters
Resistive loads keep the voltage
and current waveforms in phase,
while reactive loads cause the
current waveform to lead or lag
the voltage waveform.
Chapter 8 — Inverters
Inverters are available in
many different configurations and ratings.
Chapter 8 — Inverters
Stand-alone inverters are connected to the battery
bank.
Chapter 8 — Inverters
Interactive inverters are connected to the PV array.
Chapter 8 — Inverters
AC modules include small
inverters in place of the
DC junction box.
Chapter 8 — Inverters
Solid-state switching
devices used in PV
inverters include transistors and thyristors.
Chapter 8 — Inverters
Line-commutated inverters
use an external AC signal
to activate and deactivate
the inverter switching
devices.
Chapter 8 — Inverters
H-bridge inverter circuits use
two pairs of switching devices
to direct a DC input to the
output in both directions.
Chapter 8 — Inverters
Push-pull inverter circuits use
one pair of switching devices
and a transformer to
alternate the direction of
direct current.
Chapter 8 — Inverters
Square waves can be modified
by adjusting the duration and
magnitude of the pulses.
Chapter 8 — Inverters
Combining multiple
modified square waves
with different magnitudes
and durations results in a
multistepped modified
square wave that more
closely approximates a
sine wave.
Chapter 8 — Inverters
Pulse-width modulation at high frequencies generates
the truest approximation of a sine wave.
Chapter 8 — Inverters
Power conditioning units
are inverters that also
perform other power
control and conversion
functions.
Chapter 8 — Inverters
Transformers use induced
magnetic fields to transfer
AC power from one circuit
to another and transform
the power to higher or lower
voltages.
Chapter 8 — Inverters
The primary and
secondary windings in
an autotransformer
share some of the same
windings.
Chapter 8 — Inverters
Inverter nameplates
include much of the
needed information for
sizing and operating the
inverter.
Chapter 8 — Inverters
At high temperatures, an
inverter may limit current
input by raising the input
voltage, which also
lowers power input and
output.
Chapter 8 — Inverters
Most inverters operate
from a relatively wide
range of input voltages,
but the range for MPPT
operation is smaller.
Chapter 8 — Inverters
In order to output AC
voltage within the specified range, the DC input
voltage must meet certain
minimum values.
Chapter 8 — Inverters
Inverters may limit
maximum DC input
current with increasing
DC input voltage.
Chapter 8 — Inverters
Most sine wave inverters
maintain high efficiency
over a wide operatingpower range.
Chapter 8 — Inverters
Inverter enclosures may
include protective devices
such as disconnects.
Chapter 8 — Inverters
Inverter interfaces include on-board screens, remote
data monitors, and computerized data acquisition and
processing software.