Apparatus for avoiding torque components at critical frequencies in machine drive systems

摘要

Applying different embodiments of this invention controls torque components at critical frequencies. In the first, the control is applied without using a speed signal and without attempting to actively damp the shaft 20 resonance, instead the machine 18 is controlled to avoid producing a torque component at the critical frequencies by estimating the torque disturbances from machine voltage and/or current measurements. The second embodiment uses a signal-processing algorithm enabling the use of standard speed encoders 22 to measure the small angular displacements caused by torsional oscillations in mechanical shafts. The third embodiment superimposes a signal from a damping controller 70 to the output signal of a speed or torque controller, the damping controller signal having been determined by a mathematical algorithm applied to a signal from a contactless torque measurement with suitable signal conditioning.