Importance

Loading Importance Indicators...

Abstract

Apparatus and method for controlling a motor having a stationary assembly with a plurality of winding stages for carrying motor current and further having a rotatable assembly in driving relation with a blower in an air handling system. The apparatus provides control of the pressure over a range of flow restrictions to maintain air pressure in the system at a relatively constant preselected level. The apparatus receives a preselected pressure signal representing the preselected air pressure level. A microprocessor, responsive to both the preselected pressure signal and a motor speed signal, generates a desired torque signal which is a function of the preselected pressure signal, the speed signal and a previous desired torque signal. The desired torque signal is compared to a signal representing motor torque and a comparison signal representing the comparison is generated. An IC control applies a motor voltage to one or more of the winding stages at a time in accordance with the comparison signal and commutates the winding stages in a preselected sequence to rotate the rotatable assembly. As a result, the blower is driven by varying the motor speed according to motor torque (i.e., torque compensated speed) to maintain substantially constant air pressure in the system at the preselected rate substantially independent of variations in the flow restrictions.

Loading the Abstract Image...

First Claim