Νέος σχεδιασμός και ανάλυση πολυκινητηρίου συστήματος χαρτοποιητικής μηχανής

The drive systems of tissue paper machines present various electrical and mechanical problems according to empirical data, which can be attributed to the used design methods. The present thesis aims at solving of such problems. The problems are: the partial treatment of the load sharing in sections, where two motors drive the same mechanical load, the overloading of one of the two main sections of the machine and the interruption of its operation when these sections are mechanically engaged. Concerning the mechanical part of the drive, problems arise due to torsional oscillations created by the resonance phenomena or the shafts torque amplification. In order to achieve the aim, an analysis is carried out of the current structure of the drive systems and the problems due to this structure are brought out. A modified structure and a new design of the drive system are proposed. A control method is proposed to share the load between the two DC motors of the same section and investigation, analysis and simulation of a drive are carried out. The behavior of the drive with elastic shafts is examined. In order to face the overloading of one of the two main sections of the paper machine, a control method is proposed to share the total load to the two main sections of the machine and an analysis of the steady state and dynamic behavior through simulation is carried out. The correctness of this control method is examined in the case of typical faults in one of the power converters. In order to face the mechanical problems an exhaustive analysis is carried out concerning torsional oscillations. Using the proposed design and control methods, the load sharing, according to the nominal power of the motors, is assured for the sections where two motors drive the same mechanical load. The overloading of one of the two sections is completely faced and the interruption of the machine operation is avoided. Torsional oscillations analysis emerges that guidelines can be given for the selection of suitable shafts and motors, namely the correct dimensioning of the system.