Capacitor in a switching circuit

[nothing909]

Homework Statement
This is a switching circuit for a switched reluctance motor. At the right hand side of the circuit attached below, there's a 47μF capacitor. What is the need for that?

The attempt at a solution
Is it to reduce harmonics or ripple, or something of the sort?

 

[gneill]

Is it to reduce harmonics or ripple, or something of the sort?

Something like that. It's meant to keep switching noise and voltage dips due to sudden high-current changes in a load out of the power supply and other circuits. Usually there should be another smaller capacitor in parallel with it since the larger valued capacitors like 47 μF are usually electrolytics and have practical characteristics that are better at lower frequencies. A small non-electrolytic in parallel will deal better with high frequency noise. Look up "decoupling capacitor".