PWM Question

[alisarhangpour]

Hello everybody,
I need deep info on Pulse Width Modulation.Specially those used in inverters.
OK, A sine wave is compared with a sawtooth wave, switching times
are decide so. But I see that some inverters use an EPROM which
keeps the switching schem (I guess so).Am I right?
If yes, how can we control the output magnitude? By ma (Modulation index)
But, With a fixed timing schem in EPROM how can we change ma?
there must be a linear relation betwin ma and switching times.
Any website?book?paper?
Thank you in advance.

 

[audioguru]

Don't make the sine wave with an Eprom. Just make an analog sinewave and change its amplitude with a voltage. Then you can rectify the inverter's output and have automatic output voltage control.

 

[audioguru]

If you insist on having an Eprom produce the sinewave, then a voltage controlled amplifier can vary its analog output level, and the inverter's output voltage can be automatically controlled.

 

[Oznog]

What do you want to drive here?
We could be talking a microcontroller, a PWM chip, or discrete components. It can be designed as a voltage output or current output.