Micro-arc Oxidation Special Power Supply Topology And Its Control System Design

Microarc oxidation (MAO) is an advanced coating process for forming ceramic oxide layer on a conductive anodic metal substrate, such as Al, Mg, Ti etc. The ceramic film formed by MAO has many unique advantages, such as good ware resistance, high thermal resistance, so this technology have arosed more and more scholars' interesting, and have great commercial potential. Power source is a key equipment of MAO process. The purpose of this paper is researching and manufacturing a special power source used in MAO process. This power source can discharge 0 ~ 500V bipolar changeable pulse and the frequency also can be regulated from 0 to 999Hz. This power source will content the reseached experiment work of MAO.The first, we completed the topologic structure design of the power source. We didn't used two separate power combined method . The inverter and chopper circuit is used in the main circuit. The discharged pulse's voltage can be changed through regulated the duty ratio of the chopper circuit and used the inverter circuit to control the frequency of discharge pulse. And then the controller, based on Intel 80C196KC, is designed. The control circuit mainly include keyboard and display circuit, A/D converter circuit, and interface circuit of power device. The signal coming from the microcontroller is used as drivable signal of chopper and inverter circuit to control the IGBT and it can attain the purpose of control the discharge wave-form. Hall sensor is used to collect voltage and current signal, and the collected result displayed by LED displayer.The paper talk about how to improve the discharge pulse presicion by using constant current and constant voltage digital PID control and how to extensive the functions, which established the foundation the following reseach such as precision controlling researches and related analyse of process parameter.