Design Of High-Frequency Discharge Power Supply System For DBD Load

In recent years,with the development of science and technology and people’s increasing attention to ecological environmental protection,low temperature plasma technology is widely used in the field of material surface treatment,coating preparation,sterilization and disinfection because of its low energy consumption,high efficiency,environmental protection and other advantages.Dielectric barrier discharge(DBD)low temperature plasma generator has been widely used as an important plasma generation technology.In this paper,the DBD plasma generator is taken as the load,the load equivalent model and characteristics,inverter power regulation mode,hardware and software design and other aspects are studied.(1)Taking the DBD load as the research object,a linear RC parallel equivalent circuit model suitable for high frequency discharge was established.The load parameter measurement experiment was designed and the characteristics of the load parameters changing with the discharge power were summarized.The relationship between the load current considering the transformer leakage and the output voltage and working frequency of the power supply was obtained.(2)Based on the capacitive characteristics of DBD load,series resonant inverter is selected as the main circuit structure and its power regulation mode is studied.On the basis of comparing and analyzing the advantages and disadvantages of series resonance and parallel resonance,series resonance inverter is selected as the main circuit structure in this paper.Based on series resonant inverter,PFM,PDM and traditional PS-PWM power regulation methods and their advantages and disadvantages are analyzed.Among them,the advantages and disadvantages of two phase shift power modulation schemes are compared,and the suitable scheme for this power supply is determined.Finally,considering the system instability caused by the change of DBD load parameters,the PS-PWM power regulation mode with current zero crossing phase locking is adopted.Through the working mode analysis of inverter,the power regulation mode can effectively reduce the switching loss at the same time.(3)According to the principle of PS-PWM power regulation mode with current zero crossing phase locking,the scheme of load current zero crossing phase locking control based on DSP e CAP module is designed,and combined with the characteristics of PFM power regulation,a hybrid power regulation control scheme is developed,which firstly powers on soft start,then sweeps frequency to determine the best working range,and finally involves current zero crossing phase locking control.(4)The hardware and software system of high frequency discharge power supply with DBD load are designed.The hardware design of high-frequency transformer and compensating inductor,control board circuit(DSP circuit,communication circuit)and main circuit board circuit(grid driver circuit,current sampling and conditioning circuit,zero crossing comparator circuit)is completed,and the software system design flow is given.At the same time,the man-machine interface is designed,which is convenient to check the real-time operating parameters of the power system on site.(5)The prototype of the power supply system was built,and the predetermined power-on process,PS-PWM power regulation and current zero crossing phase lock control were realized.Moreover,the system could run stably for a long time,which verified that the designed high-frequency discharge power supply had good performance and met the operation requirements of the system.