Conception Design Of The Power Supply For Magnetic Island Divertor Configuration On J-TEXT

One of the main tasks faced by ITER(International Thermonuclear Experimental Reactor)and future fusion reactors is to reduce the local thermal load on the divertor target plate.An important research direction at present is to increase the radial transport of the scraping layer.Drawing on the idea of a magnetic island divertor on a stellarator,J-TEXT(Joint Texas Experimental Tokamak)Tokamak proposed to use an external resonance disturbance field to generate and control the boundary magnetic island structure in order to achieve the goal of reducing the local thermal load on the divertor target plate.In order to make the magnetic island structure have a certain dynamic adjustment capability,which is convenient for experimental observation,The designed power supply of magnetic island divertor should be able to work under the condition of DC,switching between trapezoidal wave and pulse wave,and frequency adjustable under the condition of low frequency.Specific power supply parameter requirements: the output current is DC or AC sine wave,the operating frequency is 0～100 Hz;when the frequency is 100 Hz,the amplitude is "± 5000 A",running for 1 s every 5 minutes;miniaturization and High degree of modularity.In this paper,according to the physical requirements of the magnetic island deflector,a low-frequency pulsed high-current power supply is designed.Four identical modules are connected in parallel to make up for the shortage of the current resistance of a single switching device.The main circuit of each module consists of a three-phase full-bridge thyristor rectifier circuit,a DC-side LC filter circuit,an H-bridge inverter circuit,and an output-end filter circuit.Carrier phase shifted sinusoidal pulse control is used as the control strategy,in which each H bridge of the carrier is phase shifted by 45° in turn.Using Labview graphical language,a singlephase waveform array is first generated,and the dead time is added according to the principle of "early shutdown" After phase shifting,waveform generation is completed on the host computer.After theoretical calculations,the main device parameters such as thyristors and capacitors are designed and selected.In view of the difficulty that the equivalent impedance changes greatly when the inductive load changes at low frequency,it is easy to cause the waveform output to be unstable.Double closed loop feedback is selected to improve the reliability of the power supply and reduce the sensitivity to the load.At the same time,the current sharing PI controller is designed to suppress the circulating current./Simulink builds the circuit and feedback model,verifies that the carrier phase-shifted pulse control can increase the switching frequency,and the current-sharing PI controller can effectively suppress the circulating current,and at the same time obtain the current output that meets the conditions under different operating conditions and the stability of the power supply after the reference current changes.Finally,according to the short working time of the power pulse and the concentrated heat production,the transformer is first optimized,the capacity of the required transformer is obtained through simulation and calculation,and the phase-shifted transformer is selected to run through the short-term overload and the circuit is charged in advance to reduce the volume of the transformer.;Then heat dissipation adopts water cooling,reduce the starting temperature of the switch tube,calculate the temperature rise of the IGBT and design the water cooling plate as a parallel flow channel structure.Using Icepak software to simulate the flow channel distance from the surface is 10 mm,and the flow velocity is 8 m/s,it is verified that the water-cooled plate can provide the switching device with a lower initial temperature to ensure performance.Aiming at the power supply layout,the laminated bus bar is designed according to the safety distance of the device to reduce the line inductance.Three layout methods are given.Based on the selection,reducing the number of water cooling pipes and the number of connections,the space utilization of the power supply is improved,so that the main part of the power supply is placed in a cabinet of 1200 mm * 1000 mm * 2200 mm,which is more power than the same power level.The volume is reduced by about 1/2.This article provides a reference for the miniaturization and layout design of low-frequency high-current power supplies.