Evaluating the influence of mechanical system vibration characteristics on servo motor efficiency

Abstract In this study, the influence of mechanical vibration characteristics on the efficiency of a servo motor was experimentally investigated. For this purpose, a dedicated apparatus comprising two servo motors connected to a coupling was used. The efficiency of the motor was investigated by first considering the signals of voltage and current; then, the mechanical power was calculated from the acquired torque and angular velocity supplied by the motor. Subsequently, working conditions involving different angular velocities and loading torques were investigated to generate a motor efficiency map. To clarify the influence of the vibration characteristics on the motor efficiency, two types of couplings differing in torsional stiffness and damping characteristics were considered—Type A and Type B. The efficiency was calculated for eight vibration conditions imposed via the selection of the velocity control gain settings for both types. Resultantly, the manner in which the efficiency is affected by the vibration conditions was clarified. Moreover, coupling in the case of better vibration damping characteristics was confirmed to yield a higher motor efficiency for all gain settings. Furthermore, motor working conditions corresponding to high and low motor efficiencies were evaluated, and the motor thermal behavior was investigated. Overall, a lower motor efficiency was confirmed to be associated with increasing temperatures. These results suggest the importance of the vibration characteristics of mechanical systems for achieving high efficiency.