Unipolar Bidirectional Current Source (UBiCS) Converter

In general, current source inverters (CSI) consist of a controlled current dc-link, which is connected to an inverter. Since the dc-link current as well as the output current have to be controlled, CSIs require a large amount of controllable semiconductors. In this paper a new topology, the Unipolar bidirectional current source (UBiCS) converter, is introduced. Although the input quantity of the UBiCS converter is a constant dc voltage, the converter behaves like a current source. The current in the inductor and the output current can be controlled only with three active switches. Similar to CSIs, no forbidden switching states exist. Unlike CSIs the output voltage of the UBiCS converter is unipolar but it allows two quadrant operation. In this paper, the basic operating principles of the UBiCS converter are explained and its advantages are derived. The validity of the concept is proven by means of experimental results. Furthermore, possible applications for the UBiCS converter are discussed.