Active filter for the DESY III dipole circuit

The DESY (Deutsches Elektronen-Synchrotron) III dipole circuit is now operated in a ramp mode cycle with a 3.6-s repetition rate. Excitation is done by a 12-pulse thyristor converter, followed by a passive filter. The existing current control could be improved by addition of an active filter. The use of a more efficient passive filter reduces the size of the active filter and does not deteriorate the dynamic behavior. The design of the control loops and the results of the simulation are presented. >