Retrofit damper system with back emf position and end stop detection

A damper system configured for installation in a ductwork including a duct supplying conditioned air through a register boot to a register vent, the damper system comprising:

• a damper frame configured to be disposed within the duct;
• damper blade pivotally mounted to the damper frame and movable between a closed end position in which the damper blade is substantially parallel with the damper frame and an open end position in which the damper blade is substantially perpendicular to the damper frame;
• an electric damper motor configured to drive the damper blade between the closed end position and the open end position;
• a controller operably coupled to the electric damper motor and configured to regulate operation of the electric damper motor;
• the controller configured to provide a drive signal that causes the electric damper motor to drive the damper blade to a desired position at or between the closed end position and the open end position;
• the controller further configured to:
• create a plurality of interruptions in the drive signal while driving the damper blade toward the desired position;
• and
• activate a sense circuit to sense a back EMF signal generated by the electric damper motor during each of the plurality of interruptions in the drive signal;
• the controller further configured to estimate a current position of the damper blade based at least in part on the back EMF signals sensed during the plurality of interruptions;
• and
• the controller is further configured to determine that the current position corresponds to the open end position when the drive signal was driving the damper blade toward the open end position and the controller determines that damper motion has stopped based on one or more of the back EMF signals, and when the controller determines that the current position corresponds to the open end position, the controller resets the estimated current position to the open end position.

A damper system configured for installation in a ductwork including a duct supplying conditioned air through a register boot to a register vent, the damper system comprising:

• a damper frame configured to be disposed within the duct;
• damper blade pivotally mounted to the damper frame and movable between a closed end position and an open end position;
• an electric damper motor configured to drive the damper blade between the closed end position and the open end position;
• a controller operably coupled to the electric damper motor;
• the controller configured to regulate operation of the electric damper motor to drive the damper blade to a desired position, the controller also configured to estimate a position of the damper blade relative to the damper frame by intermittently sensing a back EMF of the electric damper motor while the damper blade is moving toward the desired position, and to recalibrate the estimated position of the damper blade when the damper blade is determined to have reached the closed end position and/or the open end position by sensing a back EMF that is less than a threshold.