Development Of Modular Cascaded H-bridge High Power Dipole Magnet Pulse Power Supply

The HIRFL(The Heavy Ion Research Facility in Lanzhou)is the largest heavy ion research facility in China,with the largest variety of accelerated ions and the highest energy,and its main technical indicators have reached the international advanced level.In HIRFL,CSRm(Cooler-Storage-Ring main ring)plays an important role in the acceleration and accumulation of the beams,which requires high demands on the various devices in the ring,and requiring timely updates to improve the overall performance of accelerator.Among them,the upgrade of diode power supply is a challenge,requiring a power supply with extremely low current ripple,high reliability,easy maintenance and long-term stability.To this end,a new modular cascaded Hbridge high power dipole magnet pulse power supply for HIRFL-CSRm is designed in this paper.First,by analyzing the problems of existing HIRFL-CSRm dipole magnet power supply in terms of power requirements,topology scheme,control scheme and aging,and combining the advantages and disadvantages of important synchrotron accelerator dipole magnet power supply schemes around the world,this paper designs a modular,fully switched,series-parallel topology scheme based on power units.The power supply consists of two branches connected in parallel,each of which consists of four 360V/1675 A power units connected in series,with a cascaded H-bridge topology inside the individual branches.The power unit is based on 15 modular high power density voltage sources connected in parallel as AC/DC and H-bridge chopper as DC/DC.Each part of the power supply is highly modularized to meet the high power output while improving the reliability and maintainability of the power supply.Secondly,based on the proposed power supply scheme,the working principle and control strategy of the front stage voltage source module and the back stage cascaded H-bridge are analyzed and designed,where the single voltage source module adopts voltage and current double closed-loop control,the parallel connection of 15 voltage source modules adopts master-slave control and the cascaded H-bridge adopts current double closed-loop control based on Frequency doubling modulation and cascaded multilevel control.Based on this,the design of the controller in the control system is assisted by establishing the mathematical model.In addition,the design of various modules of the power supply,the digital control system,the design of various signal processing boards and the mechanism analysis and solution of cascaded H-bridge leakage current are introduced in detail.After completing the theoretical analysis and engineering design,a simulation model of the power supply system was built and simulated according to the actual parameters,and the simulation results verified the effectiveness of the parameter design and closed-loop control strategy.After the construction of the power supply,experiments were conducted.The experimental results showed that each module has complete functions and long-term reliability,and the absolute error of the output current is less than ±165 m A,the new modular cascaded H-bridge high power dipole magnet pulse power supply of HIRFLCSRm has been successfully developed.