| 摘要 |
PURPOSE:To prevent the state to abruptly decrease a torque or to become impossible to control a current by providing a circuit for preventing a speed reference from rising when the modulation factor input to a pulse width modulator exceeds a normally allowable range. CONSTITUTION:A modulation factor MU is obtained for an absolute value through an absolute value amplifier ABS, and then smoothed by an operational amplifier OA4. The smoothed factor MA is compared by a value set by a regulating resistor TH3, i.e., with an allowable modulation factor MK, and an output of the amplifier OA4 is produced 0 to positive side in case of MA-MK. In case of MA-MK, the output of the amplifier OA4 is 0 by the operation of a diode D1. A voltage detector DET energizes a relay Ry when a speed reference REF is positve. Accordingly, when the reference REF is positive and MA-MK, the output REF of an acceleration limiter decreases irrespective of the reference REF2. As a result, the speed decreases, and the modulation factor becomes small. |
