1. Sinusoidal Pulse-Width Modulation
In multiple-pulse modulation, all pulses are the same width
Vary the pulse width according to the amplitude of a sine wave evaluated at the center of the same pulse
ECE 442 Power Electronics

2. Generate the gating signal
2 Reference Signals, vr, -vr
ECE 442 Power Electronics

3. Comparing the carrier and reference signals
Generate g1 signal by comparison with vr
Generate g4 signal by comparison with -vr
ECE 442 Power Electronics

4. Comparing the carrier and reference signals
ECE 442 Power Electronics

5. Potential problem if Q1 and Q4 try to turn ON at the same time!
ECE 442 Power Electronics

6. If we prevent the problem
Output voltage is low when g1 and g4 are both high
ECE 442 Power Electronics

7. This composite signal is difficult to generate
ECE 442 Power Electronics

8. Generate the same gate pulses with one sine wave
ECE 442 Power Electronics

9. Alternate scheme
ECE 442 Power Electronics

10. rms output voltage Depends on the modulation index, M
Where δm is the width of the mth pulse
ECE 442 Power Electronics

11. Fourier coefficients of the output voltage
ECE 442 Power Electronics

12. Harmonic Profile
ECE 442 Power Electronics

13. Compare with multiple-pulse case for p=5
Distortion Factor is considerably less
ECE 442 Power Electronics