| 摘要 |
PROBLEM TO BE SOLVED: To maintain safety of controlling even in a low-speed regenerative state and to prevent stepping-out. SOLUTION: A speed correcting value arithmetic means obtains a speed estimating value fr ' corresponding to a slip frequency fs ' at a boundary line (4), when a slip frequency fs obtained by a slip frequency arithmetic means is larger than the slip frequency fs corresponding to the sped estimated value fr estimated by a magnetic flux speed estimating means at the line (4); and adds the difference between the fr ' and the fr to the previous time speed correcting amount Fcmp as this time speed correcting amount Fcmp . |
