Latency effect in a variable speed control on torsional response of elastic drive systems

Torsional vibration issues in elastic drive systems are a well-known topic also in the industrial field. The torque pulsations produced by the drive are the main causes of these torsional resonance excitations. However, it will be analysed in this paper how some side-effects in the control strategy, like the latencies, are critical as the torque ripple. Indeed, the suppression of this vibrations phenomenon cannot be achieved correctly without analysing and quantifying the time-delays that affect the system. This paper aims to provide both a comprehensive analysis on such latencies and introduces a method to proof the relationship between the damping capability of the process and the time-delays. It will be defined a process damping coefficient in order to explain the relations between the electrical damping, related to the control architecture, the latencies and the mechanical damping.