PS-PWM Control And Human-Machine Interface Of Power Supply For Plastic Film Surface Treatment

Corona surface treatment of plastic film is applied more and more widely in plastic industry such as printing, packaging and etc. After the corona treatment, the coarseness and wetting quality of plastic film is improved and surface adhesion of material is enhanced also so that the ink prints on the plastic surface much more easily than before.Firstly, some basic knowledge is introduced such as the electrical characteristics of dielectric barrier discharge (DBD), the principle and equipments of corona surface treatment, the factors which affect the treatment result and the techniques of power supply and human-machine interface and etc. By comparison, PS-PWM control is chosen as the control method of power supply for plastic film surface treatment.After summarizing the advantages and disadvantages of three PS-PWM control methods, the control method of inductive PS—PWM is chosen. Load's nonlinear changing and the significance of load's frequency tracing by phase-locked loop (PLL) is proved by experiment result. The blue print is discussed in detail and the design of control system is also outlined which has the advantages of realizing the frequency trace automaticly and achieving high power factor output.Hardware and software of the human-machine interface based on AT89C55WD is analyzed which can accomplish many functions such as parameters measuring, exception detecting, display controlling, output power adjusting and etc. Control of output power is realized by 81C55 internal counter and F/V circuit with advantages of high independence and little demands. Frame format and communication protocol is introduced detailedly and monitor software based on VB6.0 is accomplished which can monitor the power supply in remote control office. The difference of hybrid interface of two control methods (PS-PWM and PAM) is compared and different calculational methods of output power are also given.Some factors are validated which affect the result of surface treatment through the change of coarseness and water contact angle of plastic film by experiment and the significance and wide application area of corona discharge in material surface treatment is proved at last.