Abstract: A uninterruptable power supply system for supplying an electrical DC load with electric energy from an electrical network comprises an active rectifier connectable to the electrical network for rectifying an AC voltage into a DC voltage, a split DC link to be supplied from the active rectifier, the split DC link comprising two capacitors interconnected in series between a positive output and a negative output of the uninterruptable power supply system, wherein a DC link neutral point is provided between the two capacitors, and a balancing buck/boost converter connected in parallel to the split DC link between the positive output and the negative output and connected via an inductor to the DC link neutral point, such that the buck/boost converter is adapted to balance the two capacitors of the DC link, wherein an unbalance between the two capacitors is generated by one or more electrical DC loads connected between the positive output and the negative output, between the positive output and the DC link neutral