Method for monitoring the control of an electronically commutated electric machine

A linear actuator comprising:

• an electronically commutated electric machine having a rotor and a stator wherein the rotor rotates in a first direction of rotation;
• and
• a control device with instructions for:
• sensing back electromotive force of coils of the stator, with a back electromotive force (BEMF) observer;
• and
• at least one of outputting a fault message and transferring the electric machine to a safety operating state when at least one of:
• a validity condition of the BEMF observer is satisfied and the absolute value of the difference between the BEMF angular speed and the rotation speed of the stator rotating field reaches or exceeds a first rotation speed threshold, and wherein a first time condition is satisfied;
• and
• the validity condition of the BEMF observer is not satisfied and the rotation speed of the stator rotating field exceeds a second rotation speed threshold, and wherein a second time condition is satisfied.

A brake device of a motor vehicle, comprising:

• a linear actuator;
• an electronically commutated electric machine having a rotor and a stator wherein the rotor rotates in a first direction of rotation;
• and
• a control device with instructions for:
• sensing back electromotive force of coils of the stator, with a back electromotive force (BEMF) observer;
• and
• at least one of outputting a fault message and transferring the electric machine to a safety operating state when at least one of:
• a validity condition of the BEMF observer is satisfied and the absolute value of the difference between the BEMF angular speed and the rotation speed of the stator rotating field reaches or exceeds a first rotation speed threshold, and wherein a first time condition is satisfied;
• and
• the validity condition of the BEMF observer is not satisfied and the rotation speed of the stator rotating field exceeds a second rotation speed threshold, and wherein a second time condition is satisfied.