| 摘要 |
PURPOSE:To restrain the control accuracy of a speed from being degraded by providing a resistance change estimation means which estimates a change in a secondary resistor on the basis of the current of an output from a current detection means and on the basis of the operating time so as to output the change to a speed operation means. CONSTITUTION:A resistance-change estimation device 111 to which a current is input estimates a rise in the temperature of an electric motor 4 by means of Formula I, it estimates a change in a secondary resistor by means of Formula II, and it outputs a corrected secondary resistor R2 to a current-system magnetic-flux operation device 62 and a speed operation device 72. A secondary resistor R2n in Formula II at this time is sent by a resistance measuring and setting device 12. Thereby, arithmetic is performed by using the corrected secondary resistor in the current-system magnetic-flux operation device 62 and the speed operation device 72. |
