Method and electrical circuit for operating a light source of a motor vehicle headlight with direct current, and light module of a motor vehicle headlight with such a circuit and motor vehicle headlights with such a light module

摘要

The invention relates to a method for operating a light source (11) of a motor vehicle headlight (1), which is intended to be operated with an alternating current, with a direct current. The light source (11) has an inductive load (Lz). The light source (11) is arranged between bridge branches of an electrical H-bridge circuit (25) with four semiconductor switches (HSL, HSR, LSL, LSR). In alternating current operation, the light source (11) receives the alternating current via the H-bridge circuit (25). The two semiconductor switches (HSL, HSR) of the H-bridge circuit (25) arranged at the top are each controlled via a bootstrap circuit (24) each with a bootstrap capacitor (Cb). In order to achieve the longest possible direct current operation of the light source (11) with as little effort as possible, it is proposed that in direct current operation from time to time at least one of the closed semiconductor switches (HSL, LSR; HSR, LSL) of the H-bridge circuit (25) briefly switched off for a recharging process and switched on again at the end of the recharging process, the recharging process being ended before the current (I (Lz)) flowing through the bridge arm of the H-bridge circuit (25) reaches a value of 0 amperes.