An energy storage device for generating an n-phase supply voltage includes a plurality of energy supply branches that are connected in parallel, each of which is connected to an output connector of the energy storage device. Each of the energy supply branches includes a plurality of energy storage modules that are connected in series, each having at least one energy storage cell, and having a plurality of coupling modules connected to one of the plurality of energy storage modules, respectively, each configured to couple, or to bridge, the connected energy storage module with the energy supply branch. The energy storage device further includes a control system.