LC Filter for High Accuracy and Stability Digital MPS at PLS

High accuracy and stability digital controlled power supply for magnet (DigCon-MPS) is developed at PLS. This power supply has three sections. The first section is digital controller including DSP&FPGA and precision ADC, the second section consists of IGBT driver and four quad IGBT switch, and the third section is LC output filter section. AC input voltage of power supply is 3-phase 21V, output current is 0 ∼ 150 A dc. Switching frequency of four quad IGBT switch is 25 kHz. The output current of power supply has very high accuracy of 100 μA step resolution at full range and the stability of +/-1.5 ppm for short term and +/-5 ppm for long term. This paper describes characteristics of filter and output current performance improvement after LC output filter at four quad digital power supplies.