The Research And Realization Of The Charging Controller For The Opening And Closing Of The Permanent Magnet Vacuum Switch

Circuit breaker is an important protective equipment in power system,among which permanent magnet vacuum switch has become a research hotspot due to its excellent arc extinguishing ability and reliability.The permanent magnet vacuum switch performs the opening and closing action through the operating mechanism,and its energy comes from the excitation current provided by breaking and making energy storage capacitor.The state of the capacitor directly affects the dynamic and static characteristics of the permanent magnet vacuum switch.At present,there are few researches on the charging of breaking and making energy storage capacitor,and the system voltage is widely used for direct power supply,which has such problems as slow charging and great damage.In this thesis,the breaking and making energy storage capacitor charging controller is studied,using the LCC resonant converter as the main circuit topology,based on the analysis of intermittent harmonic current mode(DCM),on the basis of output characteristic,in order to solve the traditional frequency conversion control is difficult to maintain a constant current output,in the process of charging,the issues that led to the charging time to extend the proposed fuzzy constant current control algorithm based on resonance frequency tracking,realizing the rapid and constant current charging points breaking and making energy storage capacitor.The main research work of this dissertation is as follows:1.Research on main circuit of charging controller based on LCC resonant converter.Through theoretical analysis of DCM2 and DCM1 modes of LCC resonant converter,the DCM2 mode with stronger current output capacity was determined as the working mode.A mathematical model was established for the output characteristics of DCM2 mode,and the variation law of resonance frequency in the charging cycle was explored to provide theoretical basis for the proposed critical intermittent resonance mode.2.Research on fuzzy constant current control algorithm based on resonance frequency tracking.Based on the analysis of the current output characteristics of the traditional frequency conversion control algorithm,the factors that influence the current output capacity are studied,the critical intermittent resonant mode is proposed,and the realization method of resonant frequency tracking is given to improve the current output capacity of the resonant converter.In view of the traditional frequency conversion control algorithm can not adapt to the changing steady-state operating point during the charging process,this paper proposes a fuzzy constant-current control algorithm based on resonant frequency tracking.The simulation shows that this algorithm can maintain constant current output and effectively improve the current output capacity of LCC resonant converter.3.Realization of breaking and making energy storage capacitor charging controller system.A prototype charging controller based on DSP28335 is built based on modularization.The transformer leakage inductance is used as the series resonant inductor and the parameters of the high-frequency transformer and resonant capacitor of the main circuit are designed according to the performance index.This dissertation expounds the design idea and realization principle of hardware circuit,and completes the corresponding control program design.4.Experimental research and analysis.The resonant frequency tracking method proposed in this thesis is proved to be feasible by the resonant frequency tracking experiment.The experimental results show that the proposed fuzzy constant current control algorithm based on resonant frequency tracking can effectively improve the power transmission capacity of LCC resonant converter and meet the charging requirements.Through the charge-discharge experiment of the energy storage capacitor,it is proved that the charging controller of the energy storage capacitor designed in this dissertation is beneficial to prolong the life of the energy storage capacitor and has practical value in engineering.