A nonconventional power converter for plasma stabilization

The authors present the design and control of a nonconventional converter with a peak power of 3.6 MVA and a bandwidth ranging from DC values up to 10 kHz for nuclear-fusion experiments. The novel control technique is based on a comparison between the current reference and the load current, through a hysteresis comparator system. The required voltage waveforms have been obtained in two specified frequency ranges, with a strictly unified control over the whole bandwidth range. The conditions on the maximum phase shift and the maximum switching frequency required have all been fulfilled. Excellent results obtained by digital simulation confirm the validity of the proposed control scheme. The converter described here has been studied and designed for an experiment that has recently been proposed within the framework of the JET (Joint European Torus) project