A method for improving the modulation index using an intelligent battery pack, in which method a battery pack includes a plurality of freely interconnectable energy modules. An energy module has at least one energy cell and at least two switches, and in which method series or parallel interconnection of a respective energy module with at least one adjacent energy module of the battery pack is implemented by a controller. A terminal voltage of the battery pack, which terminal voltage results from the respective interconnection, is adjusted in accordance with a respectively prespecified load demand on at least one N-phase electrical machine. The terminal voltage is connected as an input voltage to at least one multi-stage inverter, and an N-phase alternating current for supplying a respective N-phase electrical machine is formed by the at least one multi-stage inverter on the basis of a level of the input voltage.