POWER CONVERTERS

A power converter is described. The power converter comprises a plurality of series-connected converter units (521, 522, ..., 52n) and a plurality of synchronised local controllers (721, ..., 72q). Each local controller (721, ..., 72q) is associated with at least one converter unit (521, 522, ..., 52n) and are adapted to operate as a single controller for distributed current control of the series-connected converter units (521, 522, ..., 52n). A current sensor (70) provides a current feedback signal indicative of a converter current directly to at least one of the plurality of local controllers (721, ..., 72q). A main controller (74) provides a current reference signal, or current reference information for calculating a current reference signal, to the at least one local controller (721, ..., 72q) each main control cycle. The current reference signal is indicative of a desired converter current. The at least one local controller (721, ..., 72q) is adapted to optionally use the current reference information to calculate the current reference signal, and carry out current control for the associated at least one converter unit (521, 522, ..., 52n) on the basis of the current feedback signal and the current reference signal each local control cycle.