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The Islamia University of Bahawalpur
University College of Engineering & Technology
EEN-324
Power Electronics
Inverters
Chp#10
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Engr. Affifa Adeeb
INTRODUCTION
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Conversion of available DC source into AC of variable
frequency is accomplished by force commutated inverters.
The frequency of AC at output can be varied by controlling
the conduction period of thyristors.
Output voltage of inverter has periodic waveform that is
not sinusoidal but can be made to closely approximate this
desired waveform.
Inverters are used in industrial applications, including
speed control of induction and synchronous motor, aircraft
power supplies, uninterruptible power supplies (UPS), and
high-voltage DC transmision.
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Half-Bridge Inverter
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Square-wave output
Step-wave output
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VOLTAGE SOURCE
INVERTER
(VSI)
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Half-Bridge VSI
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Example 10.1
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Full-Bridge VSI
State
S1
S2
S3
S4
Output Voltage
1
On
Off
Off
On
+E
2
Off
On
On
Off
-E
3
On
Off
Off
On
+E
4
Off
On
On
Off
-E
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With Inductive RL load
Square-Wave output
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Step-Wave output
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Inverter Voltage Control Techniques
1- Control of DC input voltage supplied to the inverter
2- Control of AC output voltage of the inverter
3- Control of the voltage within the inverter
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PULSE-WIDTH MODULATION
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(A) SINGLE PULSE-WIDTH MODULATION
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(B) MULTIPLE PULSE-WIDTH
MODULATION
Variable duty cycle with
m= 5
(a) m= 2
(b) m= 3
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(C) SINUSOIDAL PULSE-WIDTH MODULATION
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PWM INVERTERS
Single-phase Full-Bridge Inverters
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