Desensitization to voltage sags of a rewinder by using an active dancer roll for tension control

Continuous processes in the paper, plastics, textile and other industries, require several drives working in synchronism. Regulation of the mechanical tension in the material is a prime quality criterion. We propose strategies and a control structure that incorporate an active dancer roll in a rewinder system to improve performance of the tensioning loop to disturbances such as voltage supply fluctuations. The linear actuator is used to close a tension loop, the adjoining nip stage maintains the linear actuator close to its mid range of operation and the winder roll is velocity controlled. The effects of voltage variations on the flux observer in the variable speed drives and on loss of performance of the induction motor drives are highlighted. The results show the potential of the proposition as a retrofit option to reduce sensibility to voltage sags in winding systems with little modification to the actual controllers