PURPOSE: To provide a method by which the torsional vibration of a motor can be suppressed well even at a higher resonance frequency.
CONSTITUTION: A motor speed control system provided with a mechanism which transmits the drive torque of a motor to a load through a drive shaft having a torsion spring system controls the torque of the motor by using a signal TRFM obtained by adding a motor load torque estimating signal TRFL calculated form the output signal TRFA of a speed controller 11 and a speed signal detected from the motor to the output signal of the speed controller 11 as a new torque command. Therefore, the amplitude of the vibration of the motor can be prevented from becoming larger by offsetting the load torque of the motor and, at the same time, a damping element is generated in a vibrating system by controlling the speed of the motor by using a signal obtained by subtracting a damping control signal calculated from the signal TRFL from a motor speed command signal as a new speed command signal. In addition, the torsional vibration of the drive shaft generated when the motor is accelerated or decelerated or the load abruptly changes can be suppressed and the load responding characteristic of the motor can be improved.
HAMADA KANEYUKI
HAMAMOTO HIROAKI
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