1. A method for controlling a modular converter with a plurality of converter modules, each converter module having two power connectors, power semiconductors and an energy storage and/or and energy source, wherein the power connectors are short-circuited in a first switching state of the semiconductors and are connected to the energy storage and/or energy source in a second switching state of the semiconductors, the method comprising: selecting possible future switching sequences of the converter based on an actual converter switching state, wherein a switching sequence is a series of converter switching states with at least one converter switching state, and a converter switching state includes switching states of the converter modules; predicting a future current trajectory for each switching sequence based on actual internal currents and on actual internal voltages; determining candidate sequences from the switching sequences, wherein a candidate sequence is a switching sequence with a current trajectory that respects predefined bounds with respect to a reference current or, when a predefined bound is violated, moves the current trajectory closer to the predefined bound; predicting future module voltages for each candidate sequence based on actual module voltages and the current trajectory of a respective candidate sequence; evaluating a cost function for each candidate sequence, wherein the cost function is based on converter switching states of the switching sequence, future module voltages and/or future currents; and selecting a next converter switching state as a first converter switching state of a candidate sequence with a minimal cost among evaluated cost functions.