Analysis of a drive system consisting of two DC motors driving the Yankee drying cylinder of a tissue paper machine

In this paper the analysis of a drive system consisting of two D.C. motors driving the Yankee drying cylinder of a tissue paper machine is presented. Two 6-pulse thyristor converters connected to the same power transformer feed the motors. The motor, which has on it the tachogenerator to measure the speed, is the master motor and the other motor is the helper. Control logic is proposed to control the torque of the two DC motors. The control can be achieved in such a way that the two motors contribute equally to the total load when the DC motors are identical, or contribute partly to the total load and proportionally to their nominal torques, if the two motors are not identical. The adjustment of the acceleration time and the parameters of the controllers are investigated, in order to keep the armature current below the maximum permissible current as well as to achieve an optimum speed response of the system. The commissioning time can be reduced significantly, adjusting the acceleration time and the controllers' parameters, and so the distress of the system's electrical and mechanical parts can be avoided. Any possible damages caused by the rapid or unstable operation of the electrical and mechanical parts during commissioning and tests also can be avoided. A fine adjustment of the real system in less time during commissioning can be obtained after the determination of the acceleration time and controllers' parameters. The analysis of the system is realized using the SIMULINK software. Typical simulation results are presented.