| 摘要 |
<p>Method and apparatus for electronically commutating a direct current motor is disclosed not requiring position sensors but rather sampling induced voltage across an unenergized motor winding to derive control signals therefrom. One motor winding is energized while the voltage across another winding is sampled and integrated to provide a flux indication. The integrated voltage sample is compared to a reference and when that integrated value exceeds the reference, the next winding of the motor is enabled and the voltage integral returned to an initial value. A ring counter maintains an indication of the currently energized winding and may also be employed to cause the sampling circuit to sample the induced voltage on the winding next in the motor sequence to be energized. A system for detecting the rest position of a brushless direct current motor is also disclosed wherein a voltage pulse is applied to one armature winding and the voltage induced in another armature winding by that voltage pulse and any associated rotor motion determines the rotor rest position. To resolve any ambiguous indications, a second armature winding may be similarly pulsed and the results thereof sensed. An approach for inverting a D.C. voltage for use in energizing an induction motor is also disclosed wherein the normally applied rectangular wave form has its third and fifth harmonic content reduced to more nearly approximate the application of a sinusoidal wave form.</p> |
