Compensation Circuit Design And Heavy Load Starting System Realization For SCR Medium Frequency Power Supply

The parallel resonant SCR medium frequency power supply has played an important role in the heating industry due to its high efficiency,fast heating speed and adjustable frequency.Recently,with the development of the high frequency and high power,the puzzle of heavy load start is becoming more and more difficult,especially the power supply having been in service for some time.In order to improve the start success rate of the SCR medium frequency power supply,the auxiliary starting energy compensation circuit based on the main circuit structure had been studied and designed in this paper.The control strategy of the starting system to verify the rationality and effectiveness of the start-up system and the control strategy had been designed.The following study works had been completed.Firstly,based on the in-depth analysis of the structure,the basic principle of rectification,inverter and start process of induction heating power supply,the phenomenon of stop vibration caused by the lack of energy were be simulated and analyzed,the reason of heavy load hard start and the energy pre-charging to deal with the puzzle in heavy load were put forward.Secondly,based on the detailed analysis of the work principle,compared with several typical energy pre charging scheme and the reason of several schemes do not meet the actual needs of this subject are put forward,the paper proposed to use the energy compensation scheme combined pre-magnetizing with pre-charge.Thirdly,based on the analysis of the characteristics of the SCR medium frequency power supply,the attenuation factor of the resonant circuit and the energy attenuation regulation of the zero-input state of the load circuit were obtained,and the circuit of energy pre-charging compensation was designed by means of the combination of theory with engineering experience,and completed the components selection and the design of the compensation circuit aimed at the pre charging compensation circuit.Fourthly,the start-up process and the reliable start-up control strategy were studied,and the steps and processes of energy pre-charging starting control were designed.The interference limitation and control strategy under the high frequency interference in the grid were proposed,and a kind of shift phase limiting control strategy based on the crossing zero was proposed to deal with the phenomenon of lost pulse caused by phase fast shift.Finally,by means of observation and analysis of the multiple start-up experiments on the work site,the paper verified the rationality,effectiveness and reliability of the design and realization of the SCR medium frequency power supply compensation circuit and the heavy load start-up system.