Patent ID: 7795847
Filing Date: 2010-09-14
Classification: H02M,Y02B

Abstract:
1. A power supply device, comprising: an input for an AC input voltage or for a DC input voltage derived from the AC input voltage; an output for a load-dependent DC output voltage electrically isolated from the input voltage; a step-up converter unit connected on an input side having a charging coil, a first switching element, a freewheeling diode, a charging capacitor and a device for regulating the voltage of a converter DC input voltage provided on an output side at the step-up converter unit by a pulse-width-modulated activation of the first switching element; a switched-mode DC/DC converter connected downstream of the step-up converter unit having at least one second switching element, having a transformer for electrical isolation and having means for closed-loop controlled predefined, load-dependent voltage reduction of the DC output voltage by a pulse-width-modulated activation of the second switching element, wherein the second switching element is controlled by a constant converter pulse duty factor and the first switching element is controlled by a converter pulse duty factor such that the converter DC input voltage decreases with increasing load.