Voltage filter
Hacheurs : filtres, commutations et commande

Let's take a look at the step-down chopper we studied in [E 3 964, § 1]. It has a voltage filter at the input (figure 6). The following analysis remains valid for all other converters that require an output voltage filter. By adapting the following reasoning, it is even possible to extend the results to a voltage output filter (step-up chopper).

The filter we are studying is a second-order low-pass filter. There is therefore a risk of resonance, if the critical frequency f_c is close to the switching frequency f_dec. We should try to place the latter about a decade further away: f_dec > 10 f_c.