| 摘要 |
PROBLEM TO BE SOLVED: To estimate a rotational velocity/rotation direction of an induction motor during idling with high accuracy without decreasing a carrier frequency, the induction motor including no velocity sensor.SOLUTION: A single-phase AC voltage obtained by sweeping a frequency in a zero direction from a peak frequency of an induction motor M is applied to the induction motor M. A detection phase &thetas;_det of a current vector is calculated from α and &bgr; axial components Iαand I&bgr;of a primary current in the induction motor M by a phase computing element 8A. A phase advance amount &thetas;_cmd for a detection/calculation delay time is calculated from a sweep frequency command value by a phase advance compensator 8B. On the basis of a phase that is obtained by adding the phase advance amount &thetas;_cmd to the detection phase &thetas;_det, a compensation voltage for compensating for an error voltage is added to voltage command values Vu, Vvand Vwwhich are converted by a two-phase/three-phase converter 6, by a voltage compensation circuit 8C. |
