1. PULSE-WIDTH-MODULATED OUTPUT
Islamic University of Gaza
Faculty of Engineering
Electrical Engineering Department
PULSE-WIDTH-MODULATED OUTPUT
Pulse-width modulation (PWM) provides a way to decrease the total harmonic distortion of load current.
A PWM inverter output, with some filtering, can generally meet THD requirements more easily than the square wave switching scheme.
The unfiltered PWM output will have a relatively high THD, but the harmonics will be at much higher frequencies than for a square wave, making filtering easier.
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

2. Islamic University of Gaza
Faculty of Engineering
Electrical Engineering Department
In PWM, the amplitude of the output voltage can be controlled with the modulating waveforms. Reduced filter requirements to decrease harmonics and the control of the output voltage amplitude are two distinct advantages of PWM.
Disadvantages include more complex control circuits for the switches and increased losses due to more frequent switching.
Control of the switches for sinusoidal PWM output requires (1) a reference signal, sometimes called a modulating or control signal, which is a sinusoid in this case and (2) a carrier signal, which is a triangular wave that controls the switching frequency. Bipolar and unipolar switching schemes are discussed next.
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

3. Bipolar Switching Islamic University of Gaza Faculty of Engineering
Electrical Engineering Department
Bipolar Switching
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

4. Islamic University of Gaza Faculty of Engineering
Electrical Engineering Department
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

5. Islamic University of Gaza Faculty of Engineering
Electrical Engineering Department
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

6. Islamic University of Gaza Faculty of Engineering
Electrical Engineering Department
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

7. Islamic University of Gaza Faculty of Engineering
Electrical Engineering Department
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

8. Islamic University of Gaza Faculty of Engineering
Electrical Engineering Department
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

9. Islamic University of Gaza Faculty of Engineering
Electrical Engineering Department
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

10. Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

11. Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

12. Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6

13. Islamic University of Gaza Faculty of Engineering
Electrical Engineering Department
Introduction to Power Electronics
Dr.Moayed Almobaied
Ch8_6