Design and Study of a Series Active Filter for the 10MW-Level High Power and High Stability DC Power Supply

The output power of high stability dc power supply system, which drives the water-cooled magnet of Steady High Magnetic Field Facility (SHMFF), can reach up to tens of megawatt, so that the circuit usually adopts the realization scheme of Silicon-controlled rectifier plus LC filter. For the improvement of magnet current ripple, a novel series active filter (SAPF) is proposed, which adopts high-frequency switching technology and uses a switching power supply instead of a transistor or transformer in the traditional scheme in series at the output of the main power supply. The novel scheme has advantages of lower control complexity and less power loss, and thus higher engineering feasibility. In this paper, the system topology structure, operating principle and control policy are presented at first. Then the key part of the design is discussed, that is, how to accurately extract the output voltage ripple of the main power supply without delay. At last, a small prototype is made to verify the feasibility of the scheme.