Method for regulating a galvanically isolated DC-DC voltage converter , wherein the DC-DC voltage converter comprises a full bridge for converting a DC input voltage (UinDC) into an AC input voltage (UinAC), a transformer for transforming the AC input voltage (UinAC) into an AC output voltage (UoutAC), a rectifier for converting the AC output voltage (UoutAC) into a DC output voltage (UoutDC), said method having the steps of: ascertaining the duty cycle (D) of the full bridge ; comparing the ascertained duty cycle (D) with a duty cycle threshold value (Dth); determining an adapted value (D_ad) of the duty cycle depending on the comparison; calculating a DC input voltage (UinDCcalc) depending on an input current (I_in), the DC output voltage (UoutDC), a transformation ratio (U) of the transformer and the adapted value (D_ad) of the duty cycle of the full bridge , wherein the ascertained duty cycle (D) is determined as the adapted value (D_ad) of the duty cycle if the ascertained duty cycle (D) is greater than the duty cycle threshold value (Dth) and the duty cycle threshold value (Dth) is determined as the adapted value (D_ad) of the duty cycle if the ascertained duty cycle (D) is lower than the duty cycle threshold value (Dth) . wherein the DC-DC voltage converter comprises a full bridge for converting a DC input voltage (UinDC) into an AC input voltage (UinAC), a transformer for transforming the AC input voltage (UinAC) into an AC output voltage (UoutAC), a rectifier for converting the AC output voltage (UoutAC) into a DC output voltage (UoutDC), said method having the steps of: ascertaining the duty cycle (D) of the full bridge ; comparing the ascertained duty cycle (D) with a duty cycle threshold value (Dth); determining an adapted value (D_ad) of the duty cycle depending on the comparison; calculating a DC input voltage (UinDCcalc) depending on an input current (I_in), the DC output voltage (UoutDC), a transformation ratio (U) of the transformer and the adapted value (D_ad) of the duty cycle of the full bridge , wherein the ascertained duty cycle (D) is determined as the adapted value (D_ad) of the duty cycle if the ascertained duty cycle (D) is greater than the duty cycle threshold value (Dth) and the duty cycle threshold value (Dth) is determined as the adapted value (D_ad) of the duty cycle if the ascertained duty cycle (D) is lower than the duty cycle threshold value (Dth) . ascertaining the duty cycle (D) of the full bridge ; comparing the ascertained duty cycle (D) with a duty cycle threshold value (Dth); determining an adapted value (D_ad) of the duty cycle depending on the comparison; calculating a DC input voltage (UinDCcalc) depending on an input current (I_in), the DC output voltage (UoutDC), a transformation ratio (U) of the transformer and the adapted value (D_ad) of the duty cycle of the full bridge , wherein the ascertained duty cycle (D) is determined as the adapted value (D_ad) of the duty cycle if the ascertained duty cycle (D) is greater than the duty cycle threshold value (Dth) and the duty cycle threshold value (Dth) is determined as the adapted value (D_ad) of the duty cycle if the ascertained duty cycle (D) is lower than the duty cycle threshold value (Dth) . <EOS>