| The requirement for teabag paper increased rapidly as people's increasing favor on teabag, while teabag paper molding technology still uses traditional papermaking equipments such as Hot Oil Cylinder Dryer and Stream Cylinder Dryer in many paper mills domestically and internally. With the growing shortage of energy and the development of people's consciousness to protect environment, many factories are improving their old papermaking equipments and developing new, efficient, green facilities."Induction Heating" is appropriate technique, as it's safe, efficient, uniformity for heating, and highly automotive. In addition, it has been used in smelting and automobile industry successfully. The innovation of this paper is to apply "Induction Heating" to paper-making cylinder dryer. Based on this idea, a medium-sized electromagnetic induction heating cylinder dryer for teabag paper molding was designed and manufactured, which has a diameter of 1400 mm and a width of 1400 mm. Besides, by using SIEMENS S7-200 serial PLC products, control systems were developed, with low-cost, high degree of accuracy and convenient operation. After continual run of nearly 10 months, it works stably, meeting the requirements of production and saving energy apparently, can replace the traditional hot-oil and stream cylinder dryers.This thesis expounds the process of developing induction heating dryer system, including the elements of induction-heating power supply, design of cylinder dryer, functions of paper molding machine system components, selection of PLC control system modules, control algorithm and project implementation, as listed below:analyze of two types of inverter structure: supply-parallel mode and serial mode, compare their features respectively, choose the latter one as the power structure for paper molding cylinder dryer; introduce PWM&PFM method for capacity controlling especially the capacitive PWM&PFM method, deducted of the relationship among the power, the phase-angle, and angular-frequency; make a detailed explain ofcurrent shifting processes of inverter circuit with lossless buffer devices; take an overview of start-up and control circuit.Make an introduction of the mechanical component of the system, study functions of each PLC control subsystem, as they are paper synchronization control system, heating temperature automation control system and remote operation panel control system.Introduce the S7 -200 series PLC, communication mode, principle for control system component selection, digital filtering, feed forward and feedback control methods; list the components configure for three control subsystems, study the incremental digital PID arithmetic and several reformative digital PID arithmetic suitable for PLC application; by employing real time data diagrams and figures, give out particular description of application of digital PI arithmetic with boundary invalidation & variant proportional parameter & variant integration time in paper synchronization control system, and common PI control arithmetic in heating temperature automation control system. |
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