Patent ID: 8310851

Claim:
A method for operating an inverter having a step-up device, wherein the inverter and step-up device each have their own efficiency-optimized operating range, comprising: connecting a direct current source by a direct current link to the step-up device, wherein the direct current source has a varying specified draw current; providing a direct current link voltage by the step-up device; decreasing the direct current link voltage of the step-up device when the specified draw current of the direct current source rises and the step-up device approaches a maximum value of a pulse duty factor; and raising the direct current link voltage of the step-up device upon stabilizing of the specified draw current, wherein an input voltage of the step-up device times a transformation ratio of the step-up device minus a safety value of approximately 30% of a mean input voltage range value of the inverter is specified as an optimum direct current link voltage and an uppermost and lowermost input voltage range value of the inverter are specified respectively as an upper limiting value and a lower limiting value of the direct current link voltage, and wherein the direct current link voltage is decreased by approximately 90% of a present value if the following conditions are met: the present value of the direct current link voltage exceeds a threshold of approximately 90% of the upper voltage limiting value of the efficiency-optimized operating range of the inverter, and the specified draw current of the direct current source exceeds 125% of the present draw current, and the present draw current is approaching the maximum draw current specified as the internal current limitation of the direct voltage source, and the direct current link voltage will be raised step-by-step if: the present value of the direct current link voltage is below the optimum direct current link voltage, the present draw current corresponds to the specified draw current, and if the aforementioned conditions for decreasing the direct current link voltage are not met.