The invention relates to a system for coupling at least one DC source (9) to a controllable energy store (2), which is used for controlling and supplying electrical energy to an n-phase electric machine (1), where n≧1. In this case, the controllable energy store (2) has n parallel energy supply branches (3-1, 3-2, 3-3), which are connectable firstly to a reference rail (T−) and secondly to in each case one phase (U, V, W) of the electric machine (1). An intermediate circuit (10) is connectable on the output side via a controllable coupling circuit (12) to the energy supply branches (3-1, 3-2, 3-3) of the controllable energy store (2) and on the input side to the at least one DC source (9). An associated operating method provides for a current flow from the at least one DC source (9) into the energy supply branches (3-1, 3-2, 3-3) of the controllable energy store (2) or the phases (U, V, W) of the electric machine (1) to be controlled with the aid of the controllable coupling circuit (12).