SWITCHED-MODE POWER SUPPLY

摘要

The switched-mode power supply operates on the series resonant converter principle and comprises a first capacitor (C19) on the primary side, to which both a voltage modulated at the mains frequency and a voltage modulated at the switching frequency of the switched-mode power supply are applied. A current which is proportional to the load and has low harmonics is drawn from the mains (UN) via this capacitor and via a power factor correction circuit (D15, L15, D17, C17), so that future standards for harmonic loads on the mains are complied with or are well undershot. The series resonant converter can, in particular, be designed as a series/parallel resonant converter, the resonant converter essentially oscillating via the series tuned circuit in the normal mode, and essentially via the parallel tuned circuit in a low-power mode. The series/parallel resonant converter is thus particularly highly suitable for devices having a low-power standby mode, such as television sets or computer monitors, for example.