The Islamia University of Bahawalpur University College of
The Islamia University of Bahawalpur University College of Engineering & Technology EEN-324 Power Electronics Inverters Chp#10 1 Engr. Affifa Adeeb
INTRODUCTION 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 highvoltage DC transmision. 2
Half-Bridge Inverter 3
Square-wave output Step-wave output 4
VOLTAGE SOURCE INVERTER (VSI) 5
Half-Bridge VSI 6
Example 10. 1 7
Full-Bridge VSI State S 1 S 2 S 3 S 4 Output Voltage 1 On Off On +E 2 Off On On Off -E 3 On Off On +E 4 Off On On Off -E 8
9
With Inductive RL load Square-Wave output 10
Step-Wave output 11
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 12
PULSE-WIDTH MODULATION 13
(A) SINGLE PULSE-WIDTH MODULATION 14
(B) MULTIPLE PULSE-WIDTH MODULATION Variable duty cycle with m= 5 (a) m= 2 (b) m= 3 15
(C) SINUSOIDAL PULSE-WIDTH MODULATION 16
17
PWM INVERTERS Single-phase Full-Bridge Inverters 18
- Slides: 18