Study On Pulse Circuit For Micro Arc Oxidation

Mico-arc oxidation is a novel surface modification technology.It may produce the oxide ceramic coatings in-stiu on the surface of aluminum,magnesium,titanium and other metal and alloy surface.It can improve the material itself inherent defect and improve the comprehensive performance.Pulse power supply is a key equipment in the process of micro-arc oxidation technology,its performance will directly influence the quality of coatings.Therefore,the research of load characteristics of pulse power supply for micro-arc oxidation,and on the basic of improving power power performance,have important significance in improving the coatings performance and promoting industrial applications of micro-arc oxidation technology.In this paper,it based on the equivalent circuit of electrochemical impedance spectroscopy(EIS),considering the stage of micro-arc oxidation process,so as to obtaine the load equaivalent model of different stages.According to the experimental waveform of load,it adopted concrete load electrical parameters.On the basis of this model,according to the peak of output current in the power supply with voltage pulse,it designed the energy-feedback and constant voltage clamp circuit.The circuit suppressed output current peak,shorten the falling time of pulse current,achieved the transfer and use of inductance energy,improved the working efficiency of the circuit.In order to solve the working state and parameter selection of pulse circuit affecting energy-feedback and constant voltage clamp circuit,and considering the current is a decisive factor in the micro-arc oxidation,it designs the square wave pulse surrent circuit which is capable of outputting the spike current pulse with a steep rising edge and falling edge.By reasonable controlling working sequence of circuit,which can realize the positive and negative current pulse frequency,duty ratio and pulse number change.At the same time,in order to solve the switching lossess problem of previous stage,it design a coupled inductor type passive lossless snubber circuit,in a certain range of duty cycle,to achieve zero current turn-on andFinally,combining of theory analysis and simulation,experimental platform,and experimental results show that the design of the main circuit and matching circuit correctness and feasibility.