The whole system uses Danfoss frequency converter and process controller. Danfoss (Danfoss) frequency converter has good driving performance, adopts advanced direct torque control mode, and provides 100% maintaining full torque during closed-loop control, including zero speed. The programmable process controller can provide arithmetic and logic operations including PID operations, and can be widely used in process control fields such as load distribution, tension control, and rewinding and unwinding control. The built-in dual DC reactor that can reduce the harmonics of the main circuit by 40% greatly reduces the harmonics of the power grid. The built-in RFI filter prevents the inverter from interfering with other equipment. Built-in Profibus/DP communication card. The power element of the inverter adopts IGBT, which has a variety of functions and a wide range of programming modules can be selected. Advanced control software ensures good dynamic response (full load torque response time is less than 2ms), excellent control performance and high flexibility, extremely high output frequency resolution <0.003HZ to maintain stability when the load changes, Meet the control requirements of various control systems.
  The control system adopts AC variable frequency drive control. The system is divided into two control modes, the first level is the inverter control level; the second level is the PLC control system.
  Paper machine drive control adopts S7-400 large-scale PLC as the control center of the system, Danfoss (Danfoss) frequency converter as the drive unit, frequency resolution above 0.01HZ, frequency conversion special motor as the execution unit; Omron encoder through Danfoss (Danfoss) The process controller provides a speed feedback signal to make the paper machine drive in the speed closed-loop operation mode, so that the control system has a steady speed accuracy of 0.01%. The PLC realizes the speed chain function, speed difference control, load distribution function, total vehicle speed rise and fall, the rise and fall of each branch point and the tightening and loosening of the paper through the Danfoss (Danfoss) Profibus/DP communication protocol network and the inverter. Function, it is ideal to meet the control requirements of the normal operation of the paper machine.
  When selecting the Danfoss frequency converter of this system, all frequency converters used in the transmission part of the network part are equipped with load distribution and RFI filter configuration, and the other parts are standard frequency converters.
Speed chain control
  The speed of each branch is provided by the field bus, so that the inverter itself forms a speed chain. The inverter adopts speed closed-loop control. The speed reference value of the slave inverter is given by the master inverter, and the master inverter provides the torque signal to the slave inverter. , The slave inverter dynamically corrects the speed of the slave inverter according to the difference between its torque and the master inverter to ensure that the speeds of the two inverters are consistent. All calculations are realized by freely programmable industrial controllers.