Control Loop Performance Monitoring of Electrical Servo-Drives

In production industry modern machines include a great number of feedback controlled drives. The reliable operation of these mechatronic systems including the requested function of the control loops are essential requirements for failure-free processes. In current systems, the observation of the control-loops is mostly restricted to basic monitoring functions, such as the supervision of limits. Yet, in the process- and facility-automation various methods of control loop performance monitoring (CLPM) have successfully been applied. The implementation and adaptation of these methods into the field of controlling electrical drives is considered to be a great contribution to a higher process reliability and efficiency of machines in production industry. Detecting oscillations automatically in the inner circuits of cascaded control loops is of great importance concerning process reliability and efficiency. The objective of this study is to monitor all major signals within the cascaded position control loop during operation in order to detect disadvantageous oscillations. As a first step, procedures for detecting oscillations were applied to the speed controller of electrical servo-drives.