Development Of Arc Excitation Light Source For Emission Spectrum Of Rotating Disk Electrode

Oil monitoring is an important means to ensure the safe operation of major equipment such as aero engines and gas turbines.The rotating disk electrode atomic emission spectroscopy technology has been widely used in oil elements detection due to the strong environmental adaptability,reliable performance,and simple operation.Research has shown that the stability of the arc light source has an important impact on the results of spectral analysis.In this paper,researches are carried out from arc finite element simulation,arc stabilization circuit design,high frequency arc ignition circuit design and digital control,etc.,and a digital automatic arc ignition circuit for arc light source excitation is proposed,and the emission spectrum of the turntable electrode is designed.The new arc stabilization circuit improves the stability of arc ignition and stabilization,and realizes the digital controllable and stable output of arc.The main research contents are as follows:1.Analyzed the factors affecting the intensity of the arc emission spectrum and pointed out the design requirements of the arc excitation light source.This article designed the arc excitation light source system scheme for the emission spectrum of the turntable electrode,and pointed out the key technologies which can improve the stability of light source.2.A simulation model of the DC arc of the turntable electrode was constructed.Based on the Magneto Hydro Dynamic model(MHD),the finite element simulation method was used to analyze the electrical characteristics and physics of the arc in the case of different plasma conductivity in the range of 2～5mm electrode gap.The static volt-ampere characteristic curve of the arc was obtained,which provides a reference for the design of the circuit.3.Proposed a digital automatic arc ignition circuit for arc excitation,and established a high-frequency arc ignition circuit topology model.The spark arrestors are replaced by dual-channel thyristors,and the Buck circuit based on FPGA and current feedback is used to adjust the output voltage.In addition,the influence of circuit parameters and control strategies on the output waveform was studied.This article also designd a phase-shifted full-bridge arc stabilization circuit which can stabilize the arc current.What’s more,the experiment reduced the switching loss of the circuit through the ZVZCS soft switch,and used Hall Sensor and FPGA digital controller to realize stable control of output current.4.Developed the arc ignition circuit and the arc stabilization circuit of the turntable electrode emission spectrum arc excitation light source,and carried out the system performance test experiment.The results showed that compared with the high frequency ignition arc circuit which uses the spark arrester,the stability of the output voltage was improved when using ignition arc circuit within the gap of 2～5mm,and the voltage fluctuation was less than 4.72%;In addition,the arc stabilization circuit can achieve the output voltage stability,leading to the current fluctuation less than 0.197%when below 20 A.