| 摘要 |
PROBLEM TO BE SOLVED: To save energy in compliance with a load fluctuation (fluctuation in the number of passengers) when operation is carried out at a rates speed and lower electricity consumption when no passenger exists. SOLUTION: A torque control system, in which a motor torque estimate valueτm found from electric current flowing in an induction motor 60 is negatively returned to a torque commandτR obtained on the basis of a deviation between a speed commandωR and an actual speedωm, is constructed. On the basis of the outputτ* from the control system, toque electric current It and excitation electric current Im are controlled respectively so that the induction motor shows the maximum efficiency. At the same time, by means of a speed command changing means 300, the torque command is compared with the previously set predetermined value and a speed command is changed according to the result, and it is determined whether a passenger exists or not, and if no passenger is determined, operation of carried out at a low speed.
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