The AC Square Wave Power Supply Of Micro-arc Oxidation And Technical Study

With the rapid development of industry, the demands of lightweight materials were increased. However, the lightweight materials with corrosion resistance and wear resistance is poor, leading to its scope of application range has been limited. At this time, micro-arc oxidation technology as an emerging technology which can effectively improve the surface properties of the material, have become a hot topic in the field of surface treatment because it has a simple process, widely applicable materials, pollution-free characteristics.At present, micro-arc oxidation technology is still in the stage of exploration and development. This paper puts forward a new kind of micro-arc oxidation technology which works in AC square wave mode. This technology using the workpiece as electricity boards can process two pieces at a time and improve greatly the efficiency of production. The new technology requirements match with a new power supply. The main purpose of this paper is to develop a micro-arc oxidation power supply called MAOAC-10.This power supply can output four modes, including AC square wave, constant DC voltage, unipolar and bipolar pulse. Design of micro-arc oxidation power supply is mainly composed of two parts:the main circuit design and control system design.The main circuit of AC square wave power supply for micro-arc oxidation adopts transformer which can boost and buck, then transformer output two secondary. Alternating currents of secondary go through the rectifier with intelligent thyristor module, capacitor filter and then output continuously adjustable DC. At last the direct currents go through consisted of the four IGBT chopper circuit of the whole bridge and output to the load. One of the major power devices are adopted the corresponding protective measures to ensure the safe and reliable operation of the power devices.The control system of the power supply is composed of two parts:main control system and the auxiliary control system.The main control system is based on80C196KB SCM as control core, the main function is to achieve voltage, current and manually adjust the following parameters of the acquisition; to produce IGBT drive signal; to monitor the working state, over-current, over-hearing of IGBT, etc. Auxiliary system is based on89C52SCM as control core, the main function is to achieve all kinds of electric parameter setting and the choice of power supply mode; to display the working process of the voltage, current and working state of real-time. Between the two controls systems using the serial communications achieve real-time transmission of data and instructions. After the completion of the power supply design, it has been debugged in this paper. Debugging results show that the system has good stability and fast response speed, achieve to output of AC square wave mode and other three modes, and finish to adjust continuously of the frequency and duty cycle. Through the process test of AC square wave technology verifies the reliability, stability and applicability of the design of the AC square wave power supply for micro-arc oxidation, and the feasibility of the AC square wave mode applied to the micro arc oxidation technology.