Design And Realization Of Series Resonant Inverter Power Supply With A Function Of Discrete Variable Frequency For Magnetic Perturbation Coils On The J-TEXT Tokamak

Tearing mode(TM)is an important magnetohydrodynamic instability in tokamak plasmas,it has adverse effect on the steady-state operation of the tokamak.Externally exerted dynamic resonant magnetic perturbation(DRMP)is an effective method used to control TM.In order to study the response of TM to DRMP,two parts of DRMP coils are designed and distributed symmetrically inside the J-TEXT vessel,and each part of DRMP coils is energized by a series resonant inverter power supply(SRIPS).SRIPS can only output sinusoidal current with a selected frequency in one shot.However,as the research moves along,new physical experiments require the frequency of SRIPS should jump among several frequencies in one shot.Therefore,a modified series resonant inverter power supply(MSRIPS)with a function of discrete variable frequency is proposed in this work.By analyzing the physical experiment requirements,the supply indexes of MSRIPS are designed.Based on the principle of SRIPS,the main topology of MSRIPS is proposed.Every resonant capacitor in MSRIPS is equipped with a pair of anti-parallel SCRs,which feature the advantages of short switching time and self-commutated characteristic.The function of discrete variable frequency is realized by switching over different resonant capacitors with SCR switches while matching the corresponding driving frequency of IGBT full bridge.Sync Trigger strategy and Sync Switch-over strategy are put forward to obtain sinusoidal current waveform and realize current waveform smooth transition during frequency conversion.The frequency conversion is divided into five modes to be studied,and frequency conversion transition time is derived.The bleeder,which is composed a resistor and a thyristor,is designed to to eliminate the DC bias of SCR switch.In addition,the control strategies of current amplitude,working frequency and current phase are discussed,and the structure of control system is improved.The resistors in bleeders are made of graphite,which is very suitable for building large power and low resistance value resistor.Based on electricity-light-electricity transmission,SCR trigger system with advantages of wide pulse and low time delay is designed.The program in the FPGA controller is redesigned,and the controller can output trigger pulse corresponding to the control instruction in a reliable way.The design and upgrade of MSRIPS is completed.Afer that,some tests for the SCR trigger system,the FPGA program,the SCR surge absorption capability,the frequency conversion and the bleeder are carried out.The test results are in conformity with MSRIPS design,and indicate that MSRIPS can meet the requirements of physical experiment.MSRIPSequipment can output current with an amplitude of 2 kA when its working frequency jumps among three frequencies(2.82 kHz,4.05 kHz,4.68 kHz).Moreover,the current waveform is sinusoidal and can smoothly transit during frequency conversion.Furthermore,the frequency conversion transition time is less than 2 ms.MSRIPS has been applied to physical experiments.By using MSRIPS,expected discrete variable frequency DRMP is generated,and the phenomenon of TM being locked to discrete variable frequency DRMP is observed on the J-TEXT tokamak.