摘要 |
In the driving operation of a sensorless three-phase motor to be used in a rotation at a comparatively low speed (approximately 2000 RPM or less) and to be bipolar driven, the number of rotations and a rotating position are accurately detected from an induced voltage and a reverse rotation brake is applied in an accurate phase, and furthermore, a short brake is applied at a set rotation number signal or less also in braking. Consequently, it is possible to prevent phase switching from being carried out in an erroneous timing and to prevent a rotation in a reverse direction by an inertia.
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