1. PowerPoint® Presentation
Chapter 8
Inverters
AC Power • Inverters • Power
Conditioning Units • Inverter
Features and Specifications

2. 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.

3. Chapter 8 — Inverters
AC waveforms can take a
variety of shapes.

4. Chapter 8 — Inverters
Certain parameters are
integral to defining the
characteristics of an AC
waveform

5. Chapter 8 — Inverters
Three-phase power is
composed of three
separate voltage wave-
forms that are 120° out of
phase.

6. Chapter 8 — Inverters
Voltage variations outside
allowable ranges include
voltage drops, voltage
swells, and transients.

7. Chapter 8 — Inverters
Three-phase voltage and
current waveforms are
unbalanced if they are not
equal in magnitude and
frequency.

8. Chapter 8 — Inverters
Harmonics can add to the
fundamental frequency to
produce distorted
waveforms.

9. 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.

10. Chapter 8 — Inverters
Inverters are available in
many different configur-
ations and ratings.

11. Chapter 8 — Inverters
Stand-alone inverters are connected to the battery
bank.

12. Chapter 8 — Inverters
Interactive inverters are connected to the PV array.

13. Chapter 8 — Inverters
AC modules include small
inverters in place of the
DC junction box.

14. Chapter 8 — Inverters
Solid-state switching
devices used in PV
inverters include tran-
sistors and thyristors.

15. Chapter 8 — Inverters
Line-commutated inverters
use an external AC signal
to activate and deactivate
the inverter switching
devices.

16. Chapter 8 — Inverters
H-bridge inverter circuits use
two pairs of switching devices
to direct a DC input to the
output in both directions.

17. Chapter 8 — Inverters
Push-pull inverter circuits use
one pair of switching devices
and a transformer to
alternate the direction of
direct current.

18. Chapter 8 — Inverters
Square waves can be modified
by adjusting the duration and
magnitude of the pulses.

19. 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.

20. Chapter 8 — Inverters
Pulse-width modulation at high frequencies generates
the truest approximation of a sine wave.

21. Chapter 8 — Inverters
Power conditioning units
are inverters that also
perform other power
control and conversion
functions.

22. 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.

23. Chapter 8 — Inverters
The primary and
secondary windings in
an autotransformer
share some of the same
windings.

24. Chapter 8 — Inverters
Inverter nameplates
include much of the
needed information for
sizing and operating the
inverter.

25. Chapter 8 — Inverters
At high temperatures, an
inverter may limit current
input by raising the input
voltage, which also
lowers power input and
output.

26. Chapter 8 — Inverters
Most inverters operate
from a relatively wide
range of input voltages,
but the range for MPPT
operation is smaller.

27. Chapter 8 — Inverters
In order to output AC
voltage within the spec-
ified range, the DC input
voltage must meet certain
minimum values.

28. Chapter 8 — Inverters
Inverters may limit
maximum DC input
current with increasing
DC input voltage.

29. Chapter 8 — Inverters
Most sine wave inverters
maintain high efficiency
over a wide operating-
power range.

30. Chapter 8 — Inverters
Inverter enclosures may
include protective devices
such as disconnects.

31. Chapter 8 — Inverters
Inverter interfaces include on-board screens, remote
data monitors, and computerized data acquisition and
processing software.