| 摘要 |
PURPOSE:To perform the computation of a slip frequency command and the like more accurately by correcting the influence of change of a secondary resistance included in a vector control command computation process through observing an effective power. CONSTITUTION:An effective power arithmetic circuit 40 detects an input effective power Pi from the input current and input voltage of an induction motor 3. A secondary resistance estimation circuit 45 estimates a secondary resistance R2 of the induction motor 3 from the effective power Pi, input current detection value I1, torque current command value I2 and slip frequency omegas. Results of said estimation are reflected in the computation of magnetizing current and that of slip frequency to prevent a deterioration in computation accuracy due to change of a secondary resistance. |
