Control of Torque Pulsations and Mechanical Resonances

To increase productivity and reduce costs, drive systems having faster dynamic performance are now being employed in industry in place of the previous slower systems.

With the increased torque bandwidth associated with new motor and drive designs, the likelihood of mechanical vibration (such as torsional resonance) has increased.

This report identifies some common sources of mechanical vibration, and includes an analysis of the torque ripple magnitude and frequency content for various machine types, to enable designers to select motors appropriate to the mechanical system.

Methods of predicting mechanical resonances of some simple systems and the potential effects are reviewed.

The impracticability of measuring high-frequency torque ripple and torsional resonance with existing strain gauge torque transducer has been shown, and alternative techniques using new designs of torque transducer and then calulating torque from angular accelleration are identified.

An example drive system, suspected of having a mechanical resonance problem is analyzed and simulated.

The simulation and analytical techniques developed will provide guidance for designers facing resonance problems. Methods to control and overcome mechanical resonance are investigated using both traditional mechanical approaches and advanced electronic control.

The latter is simulated on modified versions of the example system.

With the growth of high-performance motor controller systems and the advances in power electronics and digital controllers, these methods will become increasingly important in the future.