Disclosed are an electrical driving system having an energy storage device and a method for operating the energy storage device. The invention relates an electrical driving system (200, 300, 400, 500, 600, 700) and (n-1) phase motors (2). The electrical driving system has an energy storage device (1) that has n energy supply branch circuits (Z) having multiple energy storage device modules (3). The energy storage device modules are used for generating AC (alternating current) voltage on n output terminals (1a, 1b, 1c) of the energy storage device (1), wherein n is greater than 1. Phase terminals (2a, 2b) of the motor are connected with one of (n-1) output terminals of the output terminals (1a, 1b) of the energy storage device (1), and a star point (2d) of the motor is connected with the remaining output terminals of the output terminals (1c) of the energy storage devie (1).