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Hi, sorry to jump in your post. but i would like to know how to implement feedback voltage compensation by modifying the sine look up table.
thanks
Primary inductance of your low frequency transformer at zero load should hopefully be fairly high, and the inductive reactance at the PWM switching frequency much higher than that again.
The reference lookup table you use to start off with needs to be slightly small.
If your peak value is originally set to (say) FF, you cannot easily make it larger.
The other thing is, multiplication can be slow, and doing it for every switching cycle can use up a huge proportion of processor time, so its better to construct a second lookup table that then only has to be read. Its much faster that way !!
Even at full maximum load, where is all this current going if the output voltage is zero at the zero crossing point ?
Here comes my problem: the first and the last samples (after and before zero crossing) are smaller than the h-bridge deadtime (1uS) thus there should be a very narrowed pulse or no pulse at all (once again, for the samples around zero crossing).What should I do to overcome this situation? May I increase those samples values from 6 to 10, to get a pulse duration of at least 1us? Would that affect the 50 Hz signal?
you should consider storing sinewave tables for different maximum duty-cycles, in order to allow feedback control for compensation of deviations from the expected value at each point of the curve.
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