The electrical system comprises a DC input circuit (100). An inverter (101) is connected to the DC input circuit and an input voltage is applied by the input circuit to generate an alternating voltage of variable frequency. An AC motor (103) has several windings (104) each of whose one end is connected to an AC output terminal of the inverter while the other end is connected to a neutral point of the motor windings. An energy storage element (105) of variable voltage is wired in between the neutral point and a terminal point of the DC input circuit. A DC supply is connected with the opposite ends of the energy storage element.
