Abstract: To produce a constant voltage at the output of a converter in the form of a step-up converter, current-mode control of the converter is superimposed by voltage-mode control in the range in which the input voltage applied to the inputs of the step-up converter differs slightly from the voltage produced at its outputs.

Abstract: A circuit arrangement for converting electrical energy has a static frequency converter which operates with a considerably higher frequency than the frequency to be produced, the arrangement has a heavy-duty switch, a transmitter and a rectifier on the secondary side, and a master control circuit, a regulating circuit and an auxiliary static frequency converter. The heavy-duty switches on the primary side and on the secondary side are provided for the two current directions with one transformer winding of a common transformer, and are also provided with filter sections for the low frequency range and high frequency range auxiliary frequency converters. The arrangement also is provided with quadrant shift locks at the primary side and the secondary side which determine the mode of operation of the static frequency converter in conjunction with the master circuit and the regulating circuit, whereby the output flow direction can be selected or is determined by a monitoring circuit.