| 摘要 |
A direct drive drawworks (100) has a permanent magnet motor (40) with a first set of windings (250) and a second set of windings (252), a shaft (41) extending from the permanent magnet motor (40) such that the permanent magnet motor directly rotates the shaft (41), a drum (43) connected to the shaft (41) away from the permanent magnet motor (40) such that the rotation of the shaft (41) causes a corresponding rotation of the drum (43), and a switch cooperative with the first set of windings and the second set of windings so as to cause the sets of windings to be selectively connected in parallel or in series. |
