Activation system and method for operating an electric machine

An activation system (210) for operating an electric machine (102) including a rotor winding (106) and a stator winding (104), including a control circuit device (220, 320) that is configured to be connected to the rotor winding (106) and to activate the rotor winding (106), the control circuit device (220, 320) having a highside switch (TF_H), a semiconductor component (TF_L), in particular a lowside switch, and a de-excitation switch (S1),

• wherein the highside switch (TF_H) is situated in such a way that a first terminal (F+) of the rotor winding (106) is connectable to a positive supply terminal (B+) of the activation system via the highside switch,
• wherein the semiconductor component (TF_L) is situated in such a way that the first terminal (F+) of the rotor winding is connectable to a negative supply terminal (B−) of the activation system via the semiconductor component,
• wherein the de-excitation switch (S1) is situated in such a way that a second terminal (F−) of the rotor winding is connectable to the negative supply terminal (B−) of the activation system via the de-excitation switch,
• wherein the activation system (210) is configured in such a way that during normal operation, when the semiconductor component (TF_L) is conductive and the de-excitation switch (S1) is open for the de-excitation, a de-excitation circuit (K) is formed, via which the rotor winding (106) is de-excited,
• wherein the activation system (210) is configured to attain a secure state, when at least one fault is present, by disconnecting the rotor winding (106) from the positive supply terminal (B+), and/or for a connected rotor winding (106), by de-exciting the rotor winding (106), wherein
• a) the activation system (210) includes an additional highside switch (Q1) that is connected in series with the highside switch (TF_H) so that the highside switch (TF_H) is redundantly designed, and includes an activation circuit (243) for the additional highside switch, the activation circuit being supplied with energy via at least one other activation circuit or partial activation circuit of the activation system, and/or
• b) the activation system (210) includes a fault detection circuit that is configured to bring about attainment of the secure state by means of an output signal, in particular by de-exciting the rotor winding for a connected rotor winding (106), wherein the activation system is configured, when the rotor winding (106) is de-excited via the de-excitation circuit (K), to not change the output signal of the fault detection circuit until the rotor winding is de-excited to a predefined threshold value, preferably completely de-excited, and/or
• c) the activation system (210) is configured, before and/or during a start-up of normal operation, to carry out a diagnosis to check a functionality for attaining the secure state when a fault is present.