Design And Implementation Of Power Supply Absolute Accuracy Calibration System For HIAF

High Intensity Heavy-ion Accelerator Facility(HIAF)is one of major scientific and technological infrastructure projects for the national 12 th Five-Year Plan.The power supply system is an important subsystems of HIAF.Accuracy and consistency of power supply current is the key to ensure the working efficiency of high intensity heavy-ion accelerator.Because of that the power supply in HIAF is numerous,and works in complex and changeable environment such as strong magnetism,strong electricity,etc,The DC current sensor(DCCT)and analog-to-digital converter(ADC)in the power supply will produce some errors inevitably,which will affect the accuracy and consistency of the power supply current,so it is necessary to calibrate the power supply current to reduce these errors.Based on this,an effective power supply calibration system is designed and implemented according to the actual working condition and calibration requirements of the power supply in HIAF.In this system,a current source with high precision and high stability is used to connect the DCCTs(with calibration coil),and the steady current source is the calibration benchmark,with which the calibration system can calibrate the power supplies on line.This online calibration method for DCCTs can improve the calibration efficiency.This paper describes the working principle and calibration process of the calibration system,and also introduces the key components of the system.In addition,according to the characteristics of DCCT and ADC,a more efficient calibration algorithm,which is curve calibration,is proposed.Curve calibration algorithm is an upgrade of linear calibration algorithm,it solves the problem that effective section of calibration parameters of linear calibration is limited,expands the effective section of calibration parameters,therefore,and ensures the accuracy of the current of various specifications of power supply in HIAF.Finally,while introducing the development process and technology,this paper implement the calibration system and the calibration algorithm on the hardware platform(based on Cyclone ?)by combining the characteristics of FPGA,which are fast calculation speed,high cost performance and tailorability.That the calibration system can work effectively is proved by experiments.In addition,the key components of the calibration system,such as new DCCT(with calibration coil)and steady current source,are also tested,which accumulates experimental data for further research on the calibration system.