| 摘要 |
PURPOSE:To prevent rupture of rolling material or burning of motor by providing speed reference operating means for delivering a motor speed reference to a driver, load limit deceleration rate operating means, and necessary deceleration time operating means. CONSTITUTION:A load marginal time predicting means 5 subjects a current average value RMS outputted from a driver to polynomial approximation according to the method of least squares thus obtaining a predictive curve for RMS. Current time is then subtracted from the time at an intersection of the predictive curve and an RMS limit value RTH thus obtaining a load marginal time TM. On the other hand, a load limit deceleration rate operating means 6 determines a load limit deceleration rate alpha based on a speed reference for motor and an output torque tau and a necessary deceleration time operating means 7 operates a stop time in the case of deceleration using the load limit deceleration rate alphathus determined. A deceleration timing detecting means compares the necessary deceleration time TN with the load marginal time TM and if the former is higher, the deceleration timing detecting means delivers a deceleration command E to a high speed reference operating means 4 thus lowering the speed reference and delivers a speed reference V to the driver 3. |
