Method and apparatus for power-saving, fail-safe control of an electromechanical brake

A method for controlling an electric motor, the method comprising:

• selecting an electric motor configured for control by a control circuit configured to control an electromechanical brake, the control circuit comprising:
• a switching regulator configured to control a magnitude of voltage applied to a brake coil of the electromechanical brake, wherein said switching regulator comprises at least one semiconductor switch, one diode, one capacitor and one inductor, and wherein the control circuit is configured such that, in operation, at least one signal from a process sub-system specifies the magnitude of the voltage for the brake coil;
• and
• at least one brake applying control signal from a safety sub-system that causes the brake coil voltage to be reduced to a level that is effectively zero, thereby applying the brake by opening a switch and each brake applying control signal from the safety sub-system has a corresponding diagnostic feedback signal to the safety sub-system that indicates the state of the corresponding switch;
• and
• applying at least one control signal to cause the electromechanical brake to brake the electric motor;
• wherein the switching regulator is coupled to a time-weighted feedback network whereby voltage applied to the brake coil can be varied by a control signal from a process system that specifies the time weighting of the time-weighted feedback network.

A system comprising an electric motor configured for control by a control circuit, the system comprising:

• an electric motor configured with an electromechanical brake, the electromechanical brake in communication with the control circuit, the control circuit comprising a switching regulator configured to control a magnitude of voltage applied to a brake coil of the electromechanical brake, wherein said switching regulator comprises at least one semiconductor switch, one diode, one capacitor and one inductor, and wherein the control circuit is configured such that, in operation, at least one signal from a process sub-system specifies the magnitude of the voltage for the brake coil;
• at least one brake applying control signal from a safety sub-system that causes the brake coil voltage to be reduced to a level that is effectively zero, thereby applying the brake by opening a switch and each brake applying control signal from the safety sub-system has a corresponding diagnostic feedback signal to the safety sub-system that indicates the state of the corresponding switch;
• and
• an apparatus configured to provide input to the safety sub-system and cause generation of the at least one brake applying signal;
• wherein the switching regulator is coupled to a time-weighted feedback network whereby voltage applied to the brake coil can be varied by a control signal from a process system that specifies the time weighting of the time-weighted feedback network.