Electronic Filter Design

I will not attempt to teach all of the fundamentals of filter design in a blog. But you should first realize what frequency you must filter down to an acceptable ripple. My other hint is that you should remember that the voltage on a capacitor is found to be:

V=Q/C → (dV/dt)=(dQ/dt)/C → dV/dt=I/C

Now if this jogged your memory so you can safely proceed, good. If this is new to you, put down the soldering iron. You can seriously hurt yourself and others working on three phase power. If this is a homework problem, you've been given a hint here to help you still do your own homework.