Method for switching on a multi-phase electrical machine in a motor vehicle

1. A method for switching on a multi-phase electrical machine in a motor vehicle, the multi-phase electrical machine having a rotor having a rotor winding, and a stator having a multi-phase stator winding, the method comprising:

applying a phase voltage having a phase voltage vector, in a PWM operating mode, to the stator winding, the vector corresponding in terms of absolute magnitude and direction to a pole wheel voltage vector of a pole wheel voltage;

energizing the rotor winding by an excitation current; and

deactivating the PWM operating mode, and activating a block operating mode for application of the phase voltage when at least one parameter influencing the pole wheel voltage reaches a threshold value.

2. The method as recited in claim 1 , wherein at least one of an absolute value of the pole wheel voltage vector, and a direction of the pole wheel voltage vector, is used as the at least one parameter influencing the pole wheel voltage.

3. The method as recited in claim 1 , wherein the threshold value corresponds to an absolute value of the phase voltage vector or a direction of the phase voltage vector of the phase voltage to be applied in the block operating mode.

4. The method as recited in claim 3 , wherein the absolute value of the phase voltage vector of the phase voltage to be applied in the block operating mode is defined by a DC voltage of an electrical system, connected to the electrical machine, of the motor vehicle.

5. The method as recited in claim 3 , wherein at least one of an absolute value of the excitation current, and a rotation speed of the electrical machine, is used as the at least one parameter influencing the pole wheel voltage.

6. The method as recited in claim 1 , wherein, in the block operating mode, a torque is set by specifying a specific pole wheel angle between the phase voltage and the pole wheel voltage.

7. The method as recited in claim 1 , wherein the electrical machine is operated in motor mode or generator mode.

8. A computation unit for switching on a multi-phase electrical machine in a motor vehicle, the multi-phase electrical machine having a rotor having a rotor winding, and a stator having a multi-phase stator winding, the computation unit designed to:

apply a phase voltage having a phase voltage vector, in a PWM operating mode, to the stator winding, the vector corresponding in terms of absolute magnitude and direction to a pole wheel voltage vector of a pole wheel voltage;

energize the rotor winding by an excitation current; and

deactivate the PWM operating mode, and activate a block operating mode for application of the phase voltage when at least one parameter influencing the pole wheel voltage reaches a threshold value.

9. A non-transitory machine-readable storage medium on which is stored a computer program for switching on a multi-phase electrical machine in a motor vehicle, the multi-phase electrical machine having a rotor having a rotor winding, and a stator having a multi-phase stator winding, the computer program, when executed by a computation unit, causing the computation unit to perform:

applying a phase voltage having a phase voltage vector, in a PWM operating mode, to the stator winding, the vector corresponding in terms of absolute magnitude and direction to a pole wheel voltage vector of a pole wheel voltage;

energizing the rotor winding by an excitation current; and

deactivating the PWM operating mode, and activating a block operating mode for application of the phase voltage when at least one parameter influencing the pole wheel voltage reaches a threshold value.