Comparative Research On Voltage Source And Current Source Resonant Converter For Plastic Film Surface Treatment

In daily life and industry areas, the film should often be treated so that its surface tension meets a certain standard. Given the importance and universality of treatment, it has become a crucial part in the process of film production. Treatment methods commonly used include flame treatment, chemical corrosion, corona treatment, etc. Since the first two methods are inefficient and will cause environmental pollution, corona treatment gradually becomes the major method. Corona discharge is a phenomenon that the gaseous medium self-sustaining discharge partially in a non-uniform electric field. Local electric field intensity exceeds the ionization field intensity of gas, so it leads to the ionization and excitation of gas, and produces visible light and sizzle around the electrode. Corona treatment uses the low temperature plasma by ionization, makes plastic surface produce free radicals reaction and cross-linking in the polymer, surface roughness and increases its wet ability of polar solvent, which increases the surface adhesion ability. Therefore, corona discharge has extremely vital significance in scientific research and practical applications.This paper introduces the physical structure and equivalent circuit of Dielectric Barrier Discharge (DBD) load and outlines the developing process of resonant converter in this field according to the requirement of the plastic film surface treatment applications. Resonant converter can be divided into voltage source and current source types, which topologies are introduced and advantages and disadvantages are analyzed. Ultimately, the topology and control strategy of voltage source and current source applied in this paper are determined.The operating principle of LCC voltage source resonant converter is presented in detail, including the commutation process and the operating modes. By using time domain analysis method, the expressions of each parameter in two critical modes are derived. Based on these expressions, two prototypes,120kHz/1kW and26kHz/9kW are designed. Meanwhile, the method based on the traditional theoretical calculation and finite Element simulation is applied to design and wound the high voltage transformer in detail and some design examples are given.This paper also analyses the operating principle of CLCC current source resonant converter in detail, including the commutation process and the operating modes. By using time domain analysis method, the relationship between various resonant parameters in two completely phase-locked mode are deduced. Based on these equations, the frequency variation and the input transformer current of26kHz/9kW prototype are optimized.Three prototypes are built and the experimental waveforms are presented. The treatment effect of voltage source system in high and low frequency are measured and compared. The experiment results show that higher frequency can provide higher output power and can improve the treatment effect. At the same time, the treatment effect of voltage source and current source in the same working conditions are compared in contact angle. The experiment results present that the output voltage of current source can be optimized to improve the treatment effect due to more resonant components comparing to traditional voltage source system.