2. WHAT IS AN INVERTER ??
Also known as DC to AC Converter.
DEFINITION: Converts DC to AC power by
switching the DC input voltage (or current) in a
pre-determined sequence so as to generate
AC voltage (or current) output.
4. APPLICATIONS OF INVERTER
• Used in industries for providing back up supply to ac
equipments in case of ac failure
How does an inverter work-.mp4
• Used in Air conditioners for providing supply to compressor
motor to regulate temperature
Principles & Benefits & DC Inverter Technology - Powrmatic-Midea.mp4
• Used to control speed of induction motor in industries
• Used for harmonics filtering….Etc.
5. Simple square-wave inverter to illustrate the concept
of AC waveform generation
VDC
T1
T4
T3
T2
+ VO -
D1
D2
D3
D4
SQUARE-WAVE
INVERTER
IO
S1 S3
S2S4
EQUIVALENT
CIRCUIT
7. What are harmonics ????
A harmonic of a wave is a component
frequency of the signal that is an integer
multiple of the fundamental frequency, i.e. if
the fundamental frequency is f, the harmonics
have frequencies 2f, 3f, 4f, . . . etc.
Harmonics Filtering
8.
9. Harmonic voltages and currents in an electric
power system are a result of non-linear
electric loads. Harmonic frequencies in the
power grid are a frequent cause of power
quality problems. Harmonics in power systems
result in increased heating in the equipment
and conductors, misfiring in variable speed
drives, and torque pulsations in motors.
Reduction of harmonics is considered
desirable.
10. • Output of the inverter is “chopped AC voltage
with zero DC component”. It contain
harmonics.
• An LC section low-pass filter is normally fitted
at the inverter output to reduce the high
frequency harmonics.
vO 1
+
L
C
vO 2
(LOW PASS) FILTER
+
vO 1
vO 2
BEFORE FILTERING AFTER FILTERING
INVERTER LOADDC SUPPLY
11. Variable Voltage Variable Frequency Capability
T1 T2 t
Vdc1
Vdc2 Higher input voltage
Higher frequency
Lower input voltage
Lower frequency
12. • Output voltage frequency can be varied by
“period” of the square-wave pulse.
• Output voltage amplitude can be varied by
varying the “magnitude” of the DC input
voltage.
• Very useful: e.g. variable speed induction
motor drive