Research on the Topologies of Polarity-Variable Micro Oxidation Pulse Power
|School||Harbin Institute of Technology|
|Course||Power Electronics and Power Drives|
|Keywords||MAO A double switch fly-back converter peak current control polarity-variable pulse source|
Micro oxidation technology is a rising machining technique of metal surface. This technology can generate ceramic film in the metal surface. For the produced membranous film is dense, wear-resistant and heat, this technology can significantly improve the properties of metal surface. As power is the critical equipment of micro oxidation technology, its parameters, such as voltage, current density, pulse frequency, have a very important impact on the quality of the film.This paper brought forward a new kind of power supply whose outputting current pulse is positive right-angled triangle. The topology of this power supply is a two-transistor fly-back converter working in discontinuous conduction mode. The power supply’s outputting power is 20kW. PLC was chosen as the key of whole control system. By modulating frequency, current peak and interval of drive pulse, every triangular pulse’s energy can be well controlled to insure the energy is proper whenever. In addition, the over-voltage circuit was designed, which could ensure the stability and reliability of the system.Since the film formatted by plus pulse and minus pulse is more dense, this paper brought forward four polarity-variable pulse powers which are based on the double-flyback circuit to obtain plus pulse and minus pulse. This paper described their work principle, analyzed their work mode, and simulated the main circult of each pulse power. The simulation results proved that the design of four polarity-variable pulse power is reasonable. Based on theoretical analysis and simulation results, this paper compared the advantages and disadvantages of these pulse powers, and concluded that circulation current pulse combination of topology power and circulation current- voltage pulse combination of topology power are more suitable for the actual needs of micro oxidation. The control system based on PIC microcontroller could modulate frequency, current peak, the number of positive and negative pulse.The developed one-polarity micro oxidation power was tested in the laboratory, the test results showed that this power could significantly improve the quality of film. At the same time, designed circulation current pulse combination of topology and circulation current-voltage pulse combination of topology power were tested in the laboratory. The results showed that these variable polarity current pulse source can be achieved. The micro oxidation power technology can be promoted by these topologies.