Dear All,
I am building a PWM Sine Wave Inverter using H-Bridge IGBT Configuration.
The inverter has the following stages:
- A Sine Wave Oscillator
- An unity gain inverting amplifier to generate inverted sine wave
- A Triangular wave generator
- Two Sets of Comparators to generate PWM waveform for positive and negative cycles
- Two Half Bridge IGBT Drivers to generate A and A' signals for each of the half bridge with death time considered.
- IGBT H Bridge
- Output filter.
I have calculated the pass band for output filter using 1/2 * pi * sqrt{LC} to get 20.6mH inductance and 30uF capacitance with a pass band of 100 Hz. Feeding the H Bridge output to LC filter, to my surprise, the output is almost zero, as I use the scope, I have found a very small sine signal with peak to peak voltage of 100mV! (The H Bridge output has a peak to peak of 24V)
Any suggestions?
I am just thinking that it might have something to do with the modulation index when mixing the sine waves to the triangular wave using the comparator.
Regards