| US 7,531,976 B2 | ||
| Motor drive device | ||
| Shingo Fukamizu, Osaka (Japan); Yasunori Yamamoto, Osaka (Japan); and Shinichi Kuroshima, Osaka (Japan) | ||
| Assigned to Panasonic Corporation, Osaka (Japan) | ||
| Filed on Feb. 20, 2007, as Appl. No. 11/676,644. | ||
| Claims priority of application No. 2006-042386 (JP), filed on Feb. 20, 2006. | ||
| Prior Publication US 2007/0194730 A1, Aug. 23, 2007 | ||
| Int. Cl. H02P 6/18 (2006.01) | ||
| U.S. Cl. 318—400.34 [318/400.36; 318/400.09] | 26 Claims |
| 1. A motor drive device operable to start an N-phase motor having N phase (where N is an integer of two or more) motor windings
by supplying a search current and a starting current in a search and start mode, and to drive the N-phase motor by supplying
drive current in a back electromotive force (back-EMF) voltage mode, the motor drive device comprising:
a drive signal generator operable to generate a search drive signal, a starting drive signal, and a normal drive signal;
a driver operable to produce the search current, starting current, and drive current, respectively, based on the search drive
signal, the starting drive signal, and the normal drive signal;
a pseudo-neutral-point voltage generator operable to generate a pseudo-neutral-point voltage representing the average voltage
of the N-phase motor terminals; and
a neutral point difference voltage detector operable to detect a neutral point difference voltage denoting the difference
between the neutral point voltage at a node common to the N-phase motor windings and the pseudo-neutral-point voltage, and
to output a detection result signal,
wherein said drive signal generator controls the starting drive signal based on the search drive signal and the detection
result signal in the search and start mode.
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