Importance

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Abstract

The invention discloses a control circuit for an electronically commutated motor which performs essential internal commutation and control functions and responds to external controls, usually user operated. The invention is embodied in a ceiling fan which is subject to controls over motor speed or torque and direction of rotation. The control circuit uses a differential transconductance amplifier, which is periodically balanced, for commutation timing, and control logic, which includes a bidirectional counter, designed for uniformity in count duration, irrespective of the count, direction of counting, or changes in direction of counting, and a five rank decoding structure which selects the unenergized winding stage for sensing, selects the energized winding stages for suitably sensed energization, and responds to both direction and energy controls. The internal control includes circuit protection when power is first turned on. The invention also includes an integrated circuit having the foregoing features and a novel method of operating an electronically commutated motor.

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First Claim