Sinusoidal PulseWidth Modulation In multiplepulse modulation all pulses

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 1

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

Comparing the carrier and reference signals • Generate g 1 signal by comparison with vr • Generate g 4 signal by comparison with -vr ECE 442 Power Electronics 3

Comparing the carrier and reference signals ECE 442 Power Electronics 4

Potential problem if Q 1 and Q 4 try to turn ON at the same time! ECE 442 Power Electronics 5

If we prevent the problem Output voltage is low when g 1 and g 4 are both high ECE 442 Power Electronics 6

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

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

Alternate scheme ECE 442 Power Electronics 9

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

Fourier coefficients of the output voltage ECE 442 Power Electronics 11

Harmonic Profile ECE 442 Power Electronics 12

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