400 Hz

[Grant Taylor]

I have found the Motor Generator thread to be fascinating and 
enlightening.  But it has made many a reference to the 400 Hz or other 
frequency much higher than mains line frequency.  Despite the comments 
about the frequency, I'm still confused as to why the higher than mains 
frequency was used.

Were the higher frequencies used because it directly effected the amount 
of time / duration in (fractions of) seconds between peaks of rectified 
(but not yet smoothed) power?

I ask because it seems to me like the percentage of time / duty cycle of 
raw rectified but not yet smoothed) power would be the same at any and 
all frequencies.  Is this assumption / understanding correct or 
completely off the mark?

A few different people made references to the amount of capacitance 
needed at 400 Hz et al. vs 50/60 Hz mains frequency.  Someone even spoke 
about high power DC being produced by polyphase converters and the 
possibility to tweak tweak winding voltages in order to possibly do away 
with the need for capacitors.

Am I starting to understand the motivation behind the 400 Hz or is there 
something else behind it?  Is this really playing to the (dis)charge 
time of capacitors in between peaks of rectified (but not smoothed) sources?

Aside:  I started a new thread for this very specific minutia to not 
mire the other Motor Generator thread down.

Thank you for all the comments and those who respond to help me learn 
something new today.  :-)



-- 
Grant. . . .
unix || die