Development of dipole magnet power supply for BEPC-II energy upgrading project

Purpose In order to make BEPC-II to run at a higher energy, the Institute of High Energy Physics undertook an upgrading project. One of the important factors limiting the energy boost is the power and performance of the dipole magnet power supplies; therefore, these four magnet power supplies are developed for the BEPC-II upgrading. Methods The power supplies adopt topologies of thyristor rectifiers to realize a high-power output. In the control unit of each power supply, a digital current closed loop is adopted, and the key components in the feedback loop are thermostatically controlled. In order to improve the performances of the power supplies, analog voltage regulators are added to the inner control loops. Results These four power supplies have been tested and have already been officially used in BEPC-II, and their powers have reached the requirements of the upgrading. The test results of the current stability are described and shown in this paper, which testifies that the stabilities meet the design parameters. Conclusions A digital control is applied to each SCR rectifier control. The performances of the power supplies are improved by the combination of digital current control loops and the analog voltage control loops, which makes the performances of the dipole magnet power supplies meet the requirements of the upgrading project.