Research On Power Supply Calibration System For HIRFL

Heavy Ion Research Facility in Lanzhou(HIRFL)is the first large-scale heavy ion synchrotron which integrates acceleration,accumulation,cooling,storage,internal and external target experiments and high-resolution particle detection in China.However,the magnet power supply system is an important part of HIRFL and mainly provides the current of specific excitation for the magnet to generate the magnetic field required by the accelerator.The errors of DC current transducer and analog to digital converter in magnet power supply can affect the accuracy of feedback current and read-back current of digital controller,and then influence the stability of beam.Therefore,it is necessary to calibrate the current of the power supply to reduce the device error,improve the current accuracy and enhance the beam stability.In this paper,the key technologies involved in the calibration system of DC power supply,pulse power supply and fast pulse power supply are studied.Firstly,a least square fitting calibration algorithm is proposed,and the high-precision digital power calibration system is built.Through the calibration algorithm,the collected current data are analyzed,processed,and the given coefficient and read back coefficient are calculated.The calibration results are obtained and verified.Secondly,a linear calibration algorithm is proposed,and a high-precision digital pulse power supply calibration system is built.The system collects current data based on NI PXI/ PCI-5922 data acquisition board,and then processes the data to get the calibration results and verify them.Thirdly,a polynomial fitting calibration algorithm is proposed and a fast pulse calibration system is built.Based on the pulse calibration system,the synchronous trigger function is added to solve the synchronization of data acquisition and current output.The linear calibration algorithm is used in the high-end current with good linearity,and the polynomial fitting calibration algorithm is used for the low-end current with poor linearity.Finally,the accuracy and feasibility of the calibration algorithm are respectively verified in DC power supply,quadrupole magnet power supply and Bump power supply in HIRFL.Through the research of this paper,we can draw the following conclusions: It is feasible to apply DC,pulse and fast pulse calibration technology to the power supply of HIRFL.After the calibration of DC power supply,the output accuracy and read-back accuracy of current are improved by one order of magnitude.After the calibration of the pulse power supply,the current output accuracy is improved by one order of magnitude,and the current read-back accuracy is improved by two orders of magnitude.After the calibration of fast pulse power supply,the current output accuracy is improved by 2 ～ 3 orders of magnitude.