Identification of control system of superconducting magnet

The dynamics of superconducting inductor - thyristor converter (I-C) unit for SMES have been studied through input/output relations. The input gate signal of random waveform given to thyristor converter and the response waveforms of currents and voltages of the I-C unit are sampled and memoried to form an input/output (I/O) sequence. An I/O sequence is identified by a multi-input/multi-output discrete time system (MI/MO DTS), that is, the dynamics of I-C unit is described. The dynamics of an I-C unit composed of 12 phase thyristor power converter and 100 KJ superconducting magnet have been identified by this method. The simulated outputs by the derived MI/MO DTS have closely fitted to the measured waveforms, and the optimal control system can be designed based on the MI/MO DTS. The three dimensional MI/MO DTS present a good approximation to the measured waveforms. One of the equivalent circuits is a parallel connection of R-L-C. The ac loss have been estimated from the parameters of the equivalent circuit. The simulated waveforms of equivalent circuit have closely fitted to the measured waveforms and show the method is useful for the estimation of ac loss.