Evolving the Rules of Inertia Matching

The accepted principle of matching motor to load inertia is no longer pertinent with today’s faster processors and advanced control algorithms. This outdated method increases costs and adds unnecessary mass in applications where load inertia is high and the continuous torque requirements are low. Motor inertia is only one consideration when developing an optimally performing solution requiring good bandwidth and servo stiffness.

Inertia matching was believed to address the stable control of a driven load connected to a servo motor. During the 70’s, when brush type servo motors began to replace hydraulics in the machine tool world, designers calculated the load inertia, torque, and speed requirements based on the expected performance of the machine.