| 摘要 |
PURPOSE:To prevent the commutation capacitor of a current type inverter from being overcharged by resetting the secondary time constant of an induction motor to a small value at the time of decelerating and increasing a slip amount. CONSTITUTION:A speed variation calculator 19 detects the decelerated operation state of an induction motor 1 on the basis of a speed feedback signal Wr from a speed detector 5 at the time of decelerating to output a signal S. A time constant resetter 20 so reset a secondary time constant T2 smaller than the secondary time constant at the time of normally operating as to largely correct a slip angle thetas as compared with that at the time of normally operating in response to the signal S. A slip angle is calculated at the time of decelerating from the time constant T2, a torque current reference i1q* from a speed controller 6 and a magnetic flux feedback signal phi from a magnetic flux detector 8, thereby decelerating it with an increased slip amount. |
