A method for setting a desired output voltage of a power supply branch of a controllable energy store, for controlling and supplying electrical energy to an n-phase electric motor, where n≧1. The controllable energy store has n parallel power supply branches, which each have at least two serially connected energy storage modules including at least one electrical energy storage cell having an assigned, controllable coupling unit; are connected to a reference bus on one side; and are connected to phases, respectively, of the electric motor on the other side. At least one coupling unit is controlled by pulses so that the arithmetic mean of the output voltage of a power supply branch corresponds to the desired output voltage. The energy storage cells respectively assigned to the coupling unit are switched into the respective power supply branch for a pulse duration, and are bypassed during a pause time.