| US 7,501,787 B2 | ||
| Method for controlling AC motor | ||
| Hirokazu Tajima, Mie (Japan); and Yasuaki Hachisu, Mie (Japan) | ||
| Assigned to Fuji Electric FA Components & Systems Co., Ltd., Tokyo (Japan) | ||
| Filed on Dec. 04, 2006, as Appl. No. 11/633,097. | ||
| Claims priority of application No. 2005-349333 (JP), filed on Dec. 02, 2005. | ||
| Prior Publication US 2007/0145939 A1, Jun. 28, 2007 | ||
| Int. Cl. H02P 27/00 (2006.01); H02P 27/04 (2006.01) | ||
| U.S. Cl. 318—802 [318/430; 318/806; 318/808] | 4 Claims |
| 1. A method of controlling an AC motor in which variable-speed control of the AC motor is carried out while power is supplied
to the AC motor from a variable-voltage variable-frequency inverter, the method comprising:
turning on and off at least one of semiconductor switching devices forming a main circuit of the inverter to generate a short
circuit between windings of the motor at a time when the motor is idling;
selecting a way of deriving a rotation speed estimate value for the motor on the basis of a winding current value flowing
at the time; and
starting power supply from the inverter to restart the motor on the basis of the resultant rotation speed estimate value.
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