To prevent a voltage from being abnormally increased, resulting from that a motor torque command value sharply decreases according as a speed increases, while a motor torque command value is limited to the upper limiting torque that can be output.
Characteristics of motor revolution speed regions Nm1 to Nm2 such that the change rate of a motor outputable upper limit torque for a motor revolution speed Nm is the highest, and that abnormal voltage increase is easily generated resulting from that the motor torque command value sharply decreases according, as the speed increases under the limit of the motor torque command value, based on this are changed to the real line characteristics that change ratio is smooth so that virtual upper limit motor torque can be set, and the other characteristics are made the same as an upper limit torque line that can be output so that an allowable upper limit torque line can be obtained. When the motor torque command value is to be limited, the motor torque command value is limited, based on the allowable upper limit torque line shown with a solid line, instead of the outputable upper limit torque line, shown by a wavy line under motor revolution acceleration at which abnormal voltage increase is generated.
COPYRIGHT: (C)2007,JPO&INPIT
KAWASHIMA HIDEKI
Shiro Fujitani
Kiyoshi Kuruma
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