The filter capacitor can be calculated as function of the filter inductance, the AC frequency and the filter coefficient. The next formula is used to make these calculations:

**Formula 1 **

Filter capacitance:

**Where:**

C is the filter capacitance in farads (F)

α is the filter coefficient

ω = 2 x π x f where f is the AC frequency in hertz (Hz)

L is the coil inductance in henry (H)

**Derivated formula **

**Formula 2 **

Filter capacitance II:

Where all the quantities are as in the previous formula except η:

η is the filter efficience