Design Of Modulation Pulse Power Supply For Micro-Arc Oridation

The effect of micro-arc oxidation is directly related to the features of power supply, low-frequency pulse DC generally used in MAO. A modulation power supply was designed and produced, prototype indicators are that low modulation frequency is 500Hz, high fundamental frequency is 50kHz, the duty cycle of the two waves variable within a certain range, output pulse voltage in 0 ~ 800V continuously adjustable, pulse peak current up to 10A. The power supply improves the existing MAO DC pulse power in the following two aspects.At present, power factor of low frequency DC MAO power supply is not high, active power factor was used to increase input power factor and reduce the grid harmonic pollution in the papers to break through complex control of the three-phase active power factor and restricted applications to a certain extend, a three-phase active power factor was implemented by three separate single phase active power factor converter. The feasibility of three-phase active power factor converter was proved by practical experiment, input power factor increase to 99.5% by using of active power factor converter.Satisfaction of the requirements for isolation between MAO load and power supply equipment, a scheme of high-frequency modulation low-frequency was proposed. High frequency isolation transformer was used in this structure to replace the current power frequency isolation transformer, so the weight and volume of the isolation transformer was greatly reduced. The good effects of output waveform were verified by using high-frequency isolated transformer.The overall scheme is proposed in the papers, details of main circuit topology choice, design of APFC inductors, BUCK inductor, full-bridge inverter transformers and high voltage floating driver circuit, compensation of the control and design of isolation sampling were discussed. Debug steps of power sections and common problems in the debug process were described from engineering experience.