| 摘要 |
PROBLEM TO BE SOLVED: To enhance the availability factor of an elevator by judging that difficulties are not encountered over the practical movement of the elevator even if excess current is detected in the output of an inverter, and even if a protection circuit has also been actuated once, and finding that excess current has been only temporary disorder caused by noise and the like. SOLUTION: A failure diagnosis energizing command signal 11b and the like are fed to an inverter main circuit 2 in such a way that the secondary magnetic flux signal of an AC motor 3 is canceled, in this case, since a subtracter is provided for a failure diagnosis circuit 10 wherein the subtracter detects the difference between the current value of the command signal 11b and the like, which are fed back through a current detection circuit 7, and a command current value set in advance, the operation of the inverter main circuit 2 can thereby be inspected in a state that no torque is applied to the AC motor 3. Therefore, even if an elevator is once suspended because the excess current is detected by the current detection circuit 7, if excess current is found to have been only caused by noise and the like, the running of the elevator is restored, and its availability factor can thereby be enhanced. |
