| 摘要 |
In a laser printer, methods and apparatus include commutating a brushless dc motor having three windings. A controller receives discrete motor position signals, such as from hall-effect or FG sensors, and extrapolates motor position between the signals. It commutates the motor based on the extrapolated motor position and updates motor position whenever an actual discrete signal is received. Drive signals from the controller to the motor are such that a current flowing in any of the three windings follows a generally sinusoidal waveform. High and low switches are provided per each winding of the three windings and are cumulatively switched according to an extrapolated motor position based multiplier applied to a pulse width modulation duty cycle. In this regard, lookup tables, counters, registers and the like are provided. An engine card of the printer includes an ASIC with a power driver for use with generally off-the-shelf brushless dc motors.
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