Patent ID: 6864671

Claim:
A direct current voltage converter for converting an input voltage into an output voltage comprising: a unit for preparing a reference voltage having a ground terminal which is connected with a first common fixed potential, a regulator for regulating the output voltage to a predetermined fraction of the reference voltage, wherein a first voltage, that is derived from the output voltage, is applied to a first input of the regulator, a second voltage, that is derived from the reference voltage is applied to a second input of the regulator, and a control voltage may be tapped at an output of the regulator, a pulse width modulator for comparing the control voltage with an alternating voltage, a voltage-controlled pole-changing switch comprising two inputs and an output for connecting one of the two inputs with the output, the input voltage being applied to one of the two inputs and a second common fixed potential being applied to the other of the inputs and a control terminal of the voltage-controlled pole-changing switch may be supplied by the pulse width modulator, a storage choke, the input of which is connected with the output of the voltage-controlled pole-changing switch, and the output voltage may be tapped at the output thereof, a smoothing capacitor, the first terminal of which is connected with the output of the storage choke and the second terminal thereof being connected with a third common fixed potential, a reference potential, to which the first voltage and the second voltage drop, is connected through an insulated line with the second terminal of the smoothing capacitor, and a low pass filter connected between the unit for preparing the reference voltage and the second input of the regulator, the low pass filter having a capacitor, one terminal of which is connected via the insulated line with the second terminal of the smoothing capacitor.