3.13.3 Capacitor Selection

The capacitor bank is connected from Peltier+ to GND after the fuse. It is composed of a mix of large electrolytic capacitors, solid-state aluminum capacitors and ceramic capacitors. This bank is used to start the regulator and must be appropriately rated for the highest ripple possible. However, it is important not to store excessive amounts of energy in this bank. Too much capacitance would exceed the limits the AC-DC converter.

The selected mix of capacitors is intended to balance ripple with energy storage. Two 270 µF electrolytic capacitors provide bulk energy storage, while six 22 µF solid-state capacitors add extra high-frequency ripple capacity, but not a lot of capacitance. Finally, two 1 µF ceramic capacitors are added to give some extra ripple capacity and handle the surge current.