(12) United States Patent ao) Patent No.: Us 7,772,792 B2
Kawaguchi et al. (45) Date of Patent: Aug. 10,2010
(54) ROTATION CONTROL DEVICE
(75) Inventors: Tadashi Kawaguchi, Hiratsuka (JP);
Jun Morinaga, Hiratsuka (JP)
(73) Assignee: Komatsu Ltd., Tokyo (JP)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 455 days.
(21) Appl.No.: 11/791,040
(22) PCT Filed: Nov. 16, 2005
(86) PCT No.: PCT/JP2005/021013
§ 371 (c)(1),
(2), (4) Date: May 17, 2007
(87) PCT Pub. No.: WO2006/054582 PCT Pub. Date: May 26, 2006
(65) Prior Publication Data
US 2008/0164832 Al Jul. 10, 2008
(30) Foreign Application Priority Data
Nov. 17,2004 (JP) 2004-333678
(51) Int. CI.
H02P 5/00 (2006.01)
(52) U.S. CI 318/461; 318/432
(58) Field of Classification Search 318/461,
318/432, 434, 798, 800 See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
6,054,844 A * 4/2000 Frank 322/16
To rotate a rotary body at a constant velocity, a swing control device of an electric rotary excavator controls rotation of the rotary body with a small first torque command value. By contrast, when operating a swing lever for acceleration, the rotation is controlled with a larger second torque command value. The first torque command value is generated based on a deviation between a velocity command value for an electric motor that rotates the rotary body and a measured velocity of the rotary body, and the second torque command value has a larger absolute value than the first torque command value and is obtained by adding a feed-forward torque command value to the first torque command value.
6 Claims, 14 Drawing Sheets