| 摘要 |
PROBLEM TO BE SOLVED: To quickly perform positioning stop of a rotating main shaft motor without generating overshoot.SOLUTION: An acceleration command arithmetic part 22 outputs an acceleration command as from output torque Tmb of a main shaft motor with a base rotational speed or less and an inertia Jm+JI of a whole shaft. A switching speed arithmetic part 23 outputs a control mode switching speed Vs from the acceleration command as. When a motor speed Vm is set to the control mode switching speed Vs or less, a control mode changeover switch 5 switches a speed control mode to a position control mode to make the main shaft stop at a desired rotational position. The control mode switching speed Vs may be set to a value calculated by Vs=60×√(amax×0.5) when the maximum acceleration to be achieved in this case is set to amax. Also, the inertia Jm+Jl of the whole main shaft may be calculated from a magnetic flux density command &phgr;c and a magnetic flux density estimation value &phgr;e and the motor speed Vm. |
