Importance

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Abstract

The microprocessor based controller for the fractional horsepower actuator motor includes a capacitive power backup system. The motor is used as an actuator and is coupled to an air damper or valve. In the event of a loss of power to the controller, the controller must drive the air damper or valve to a predetermined, failsafe position. The capacitive energy source stores sufficient power to drive the motor and the coupled air damper or valve to the predetermined failsafe position. The controller includes a sensor for determining the presence or absence of power and generating a failsafe control signal. A switch receives the failsafe control signal and passes power from either the main power supply or the capacitive energy storage unit. The controller includes a microprocessor and a memory. During a failsafe operation, the microprocessor drives the motor and hence the air damper or valve to the failsafe position at full power. When the position of the air damper or valve falls within a predetermined position band near the failsafe position, the microprocessor reduces the drive signal applied to the motor in order to achieve a soft landing at the failsafe position. In another embodiment, the microprocessor will reverse the direction of the air damper or valve if the position of the damper or valve is within a further predetermined position band near the failsafe position. Thereafter, the microprocessor drives the air damper or valve via the motor to the failsafe position through the soft landing system.

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First Claim