# Calculate Smoothing Capacitor

#### luca290799

Joined Apr 4, 2022
34
Sorry, I attach a better photo.
I would like to calculate the capacitance value and resistance of the Capacitor in the schematic (I think it's a DC-Link capacitor), with this parameters:
Vdc input = 15V
R=0.18 ohm
L = 0.18 henry
I have to comply a Ripple Current of 1% at the input.

This circuit will be attached to a motor with a switching frequency of 125kHz.

Thanks

Last edited:

#### crutschow

Joined Mar 14, 2008
29,792
The filter circuit is to reduce ripple from an AC source and yours is DC, so I don't understand what ripple your are concerned about(?).

#### luca290799

Joined Apr 4, 2022
34
The filter circuit is to reduce ripple from an AC source and yours is DC, so I don't understand what ripple your are concerned about(?).
I have updated the thread so that it is clearer and more detailed

#### Picbuster

Joined Dec 2, 2013
1,038
Sorry, I attach a better photo.
I would like to calculate the capacitance value and resistance of the Capacitor in the schematic (I think it's a DC-Link capacitor), with this parameters:
Vdc input = 15V
R=0.18 ohm
L = 0.18 henry
I have to comply a Ripple Current of 1% at the input.

This circuit will be attached to a motor with a switching frequency of 125kHz.

Thanks
hi,

I think that you are not talking about ripple but noise/ spikes generated by the 125Khz motor.
You do not want to feed that back into your dc supply starting to frustrate the connected systems.

the cap and coils should do the job.