| Magnesium alloy has excellent properties, such as low density, high specific strength and specific rigidity,good damping performance,good electromagnetic shielding performance etc.Therefore,magnesium alloy is applied to aviation,automotive and electronic industry increasingly.But corrosion resistance of magnesium alloy is very poor,which has badly limited its application.Usual surface treatment methods,for example,chemical oxidation and anodic oxidation,are able to protect magnesium alloy,but its corrosion resistance and external appearance etc.can't meet the needs of the application development.In recent years,People have developed some new technology,microarc oxidation can meet above demands.Microarc oxidation-also called microplasma oxidation or anodic spark deposition．is a new material surface treatment technology, which developed on the basis of anodic oxidation. Power source is a key equipment of Microarc oxidation process. At present, most power supplies used in this field are DC or unipolar pulse power supply when disposing of metal surface with micro-arc oxidation. The power supply in this paper is designed on the basic of eliminating the shortages of previous power supplies. It is an ideal, bipolar and high-power power supply, in which the amplitude, frequency, duty ratio and number of positive and negative pulse can be modulated according to the load requirements. The good porcelain can be obtained with the optimal parameter. As a result, the power supply possesses the characteristics of high efficiency, safety, reliability and convenient operation. This power source will content the reseached experiment work of MAO and industrical application.The SCR rectifier and IGBT chopper circuit were used in the main circuit. The pulse amplitude can be changed through the rectifier circuit, the output of pulse can be realized through the chopper circuit, to simplify the power structure and control strategy and decrescence the volume.And then the controller, based on TMS320LF2407A DSP is designed. The trigger pulse coming from DSP PWM is used to control the angle of trigger and the voltage can be adjusted consecutively. Also PWM signal coming from DSP is used as drivable signal of chopper circuit to control the IGBT and it can attain the purpose of control the discharge wave-form. Overcurrent protection, overvoltage protection and overheat protection is designed to keep power device work safely.In order to keep the power supply work normally in the rugged environment, the interference that affect the power supply are analyzed and some effective interference resistance are constituted. Some suggest is put forward to make the supply perfect which established the foundation of the following research.
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