Method for safe control of an electronically commutated electric machine

A linear actuator comprising:

• an electronically commutated electric machine having a rotor and a stator;
• and
• an electronic control device wherein the control device uses the signals of a rotor position sensor for controlling the electric machine, wherein the control device has instructions for:
• monitoring the signals of the rotor position sensor;
• controlling the electric machine with a control device in a transition operating mode when the signals of the rotor position sensor are faulty or fail, and when the current rotational speed of the rotor sensed in the normal operating mode is above a predefined safety rotational speed, wherein the transition operating mode comprises:
• controlling the electric machine by means of the control device in the transition operating mode, preferably by means of the signals of a BEMF observer;
• and
• detecting the back electromotive force of the coils of the stator in the transition operating mode, preferably by means of the BEMF observer, until the angular velocity of the rotor reaches or undershoots the predefined safety rotational speed, or until a validity condition of the BEMF observer is no longer met;
• and
• controlling the electric machine by the control device in a safety operating mode after controlling the electric machine in the transition operating mode.

A brake device of a motor vehicle comprising:

• a linear actuator;
• an electronically commutated electric machine having a rotor and a stator;
• and
• an electronic control device wherein the control device uses the signals of a rotor position sensor for controlling the electric machine, wherein the control device has instructions for:
• monitoring the signals of the rotor position sensor;
• controlling the electric machine with a control device in a transition operating mode when the signals of the rotor position sensor are faulty or fail, and when the current rotational speed of the rotor sensed in the normal operating mode is above a predefined safety rotational speed, wherein the transition operating mode comprises:
• controlling the electric machine by means of the control device in the transition operating mode, preferably by means of the signals of a BEMF observer;
• and
• detecting the back electromotive force of the coils of the stator in the transition operating mode, preferably by means of the BEMF observer, until the angular velocity of the rotor reaches or undershoots the predefined safety rotational speed, or until a validity condition of the BEMF observer is no longer met;
• and
• controlling the electric machine by the control device in a safety operating mode after controlling the electric machine in the transition operating mode.