Steve says:
>The rms and peak currents depend on the ratio of source and load
>resistances and the capacitor value. For a decent high power PSU (bridge
>with capacitor input) the ratio should be in the regions of 1-2% maximum
>and you will have enough capacitance that it doesn't affect the
>calculation). In these circumstances an old handbook I have puts the rms
>ripple at about 3x dc current, and peak ripple at about 12x dc while a
>spice simulation gives values of about 2x and 8x respectively.
For what it's worth, many years ago, I did some measurements using a
thermo-ammeter, and found that provided the capacitor was big enough to give
negligible voltage drop on load, the measured ripple current was 1.4 times
the DC. That was for bridge rectifiers. Being a thermo-ammeter, that should
be the rms.
73
Peter G3RZP
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|