The Optimization Design for Suppression of CRAFT TF Magnet Power Converter Switching Overvoltage

The switching overvoltage due to the operation of the switching device is considered to be one of the important research contents during the design phase of a high-power supply system based on thyristor rectifier topology in the comprehensive research facility for fusion technology (CRAFT). Switching peak overvoltage is suppressed by resistors–capacitors (RC) snubber circuit generally; however, the traditional RC design often relies on some simple empirical formulas and blind amplification margins, which is unable to meet the precision requirements of engineering design. All the work that has been done is based on the cophase counter parallel connection structure of the converter module, and a new strategy is proposed to optimize the RC snubber circuit in order to suppress the operating peak overvoltage better. First, the no-load transformer breaking overvoltage is analyzed, then RC parameters are designed based on a new strategy. Compared with traditional methods, the RC parameters selected by this strategy are more accurate, which meets the accuracy requirements of engineering design and suppresses switching better than before.