Research On DC Power Supply Current Ripple Suppression Of Heavy Ion Accelerator

The power supply system is an important subsystem of the large-scale accelerator scientific device,which combines magnets to produce the magnetic field required to control the motion of particles.Therefore,power supplies have high requirements for stability,accuracy and ripple.This thesis focuses on magnet power supply ripple rejection issues,which means a DC active filter(DAF)is used to reduce output voltage(current)ripple of power supply.Combined with engineering application,the related technology of D AF was studied.The thesis analyzed the main source of DC power supply ripple,and studied the three parts of ripple reference signal extraction,converter structure and control strategy.Firstly,the thesis put forward an improved current average value and designed a digital filter for the ripple reference signal extraction;Secondly,for the current H bridge structure converter,an additional rectifier circuit is required to maintain the stability of the storage capacitor voltage,a buck/boost converter was selected and designed;Then,for control strategy,in order to meet the working requirements of the converter and to solve the steady-state error of the PI controller tracking the ripple signal,the positive and negative half-wave current control methods and the PI + improved repetitive control method were used as control strategy.Finally,the design scheme was simulated and analyzed by using the Matlab software.Based on the work above,the hardware and digital control system were designed.The thesis proposed a program overall design scheme for making the best use of FPGA parallel computing.The control system adopted FPGA digital controller and embedded in Nios II soft core.Among them,the hard core part was described in Verilog language to realize the calcul ation function of the regulator and generate the PWM drive signal;The software program was written in C language and assembly language to realize the Ethernet communication between the controller and the host computer,as well as the related configuration of the digital regulator.An experimental prototype was built in accordance with the design scheme,and the experimental verification was completed by using the steady current power supply of Institute of Modern Physics,CAS.The test results showed that the DAF designed in this thesis has a certain inhibitory effect on low frequency ripple.Furthermore,the research of this thesis provided a reference for the ripple suppression of the subsequent DC power supplies and the design of the specific DAF.