That would be interesting to see.
It's a 3 phase BLDC control. I calculated about 10A ripple absolute max
with a spice simulation. I'm not sure how accurate my model is but I
don't think it's far off. With two capacitors per phase and a PWM of
50kHz and a maximum speed of around 5k RPM the capacitors will only see
the max current for ten PWM periods once every 100uS.
The RMS current would be max/sqrt(2) which is about 7A. Split between
two capacitors results in 3.5A ripple. I don't know how good my math is
there so I will try to do some more signal analysis but I think I'm close.
David Van Horn wrote:
{Quote hidden}>capacitor reactance.
>
>Jim Williams of Analog Devices, has a good formula for this.
>Several terms, and the results can be quite interesting.
>I used the formula for a particularly difficult thermal printer design,
>and it suggested that three really cheap caps would be better than one
>expensive "low ESR" model. I went with the guidance, and that worked
>out very nicely.
>There are scads of systems in the field now, but essentially no
>failures. :)
>
>I don't seem to have the right book on hand, so I can't quote it
>directly.
>Perhaps someone else out there does?
>
>
>
>
>
> Yes it's a continuous rating at a maximum temperature, based on the
--
Martin Klingensmith
http://wwia.org/
http://nnytech.net/