| Microarc oxidation (MAO), a new technology, can directly form oxide ceramic coatings on the surface of the valve metals such as aluminum, titanium, magnesium, hafnium etc. or their alloys. By the plasma discharging of the valve metals in an aqueous electrolyte solution, MAO produces complicated reaction including electrochemistry, hot chemistry and plasma chemistry, and it forms a hard and compact oxide ceramic coating on the surface of the valve metals and their alloys. Due to the oxide coating having many virtues such as high microhardness, good wearlessness, strong binding force with the matrixes, erosion resistance etc., MAO is extensively applied in the fields of mechanism, automobile, national defence, electronics, aviation, architecture and so on.The microarc oxidation equipment includes special high-voltage power-supply, oxide groove, cooling system and churn-dasher. This thesis introduces the research of high-voltage power-supply.MAO usually researches the properties of the oxide ceramic coatings in the mode of constant voltage or constant current. Now the power-supplies that are adopted by the persons who are engaged in this research can work in the mode of constant voltage or constant current, but the frequency of the working current and voltage they provide is only 50Hz, and the waveform and the pulse width cannot be chosen. Those restrict the properties of the oxide ceramic coating. The power-supply mentioned in this thesis can continuously adjust the frequency of the working voltage and current in the larger range, and can choose the waveform and the pulse width. The power-supply displays many electric parameters in digital, meanwhile it can record the change of the parameters by the upper computer. This thesis mainly introduces the hardware components and software framework of the multifunction microarc oxidation power-supply. Hardware components include the major loop and the control circuit. The major loop is composed of IGBT, voltage regulation circuit, commutate and filter circuit, snubber and drive circuit. The function of the voltage regulation circuit is to solely and continuously adjust cathode voltage and anode voltage in the range of 0~±1000V. Snubber controls the spike voltage as the IGBT turns off and the diode resumes to prevent the IGBT from being damaged. Drive circuit controls turnoff and ducting of the IGBT. The control circuit takes the singlechip computer as the nucleus, its peripheric circuits include data acquisition circuit, pulse width adjusting circuit, waveform chosen circuit, electric machinery circuit and interface circuit. The power-supply chooses AT89C52 as the microprocessor. The data acquisition circuit gathers four data, namely the values of cathode voltage, anode voltage, cathode current and anode current. The pulse width adjusting circuit provides the drive signal to IGBT. The drive signal is conveyed to counter T1 for the values of frequency and pulse width. We may realize that the frequency continuously adjusts in the range of 20Hz~10KHz and ratio of the pulse width is 10%~90% by choosing the proper the value of the potentiometer. The waveform chosen circuit can realize the chosen of the voltage waveform such as AC, pulse, DC etc. by the control of the program. The electric machinery circuit controls the corotation, reversal, startup and suspend of the three-phase booster in the major loop. The interface circuit mainly includes the interface of the keyboard, the indicator light, display and communication. The main components in the interface circuit are 8155, 8279 and MAX232. 8155 controls the keyboard and the indicator light. 8279 controls the display of the electrical parameter. MAX232 changes TTL into RS-232 in order to communicate between the power-supply and the upper computer.Software framework of the power-supply consisted of computer monitoring program and power-supply monitoring program. The monitoring program was respectively compiled in VB and assemble language. Chapter three mainly introduces the program flow chart.The multi...
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