Optimization method for RC snubber of high-capacity AC-DC converters

In the design process of high-capacity AC-DC converter, RC snubber circuit should be connected to thyristor in parallel in order to absorb the energy generated at the moment of thyristor switching and suppress overvoltage impulses and high voltage variable rate du/dt. However, parameter selection, which generally depends on empirical formula, sometimes results to rather great errors. Once the selection of protection parameters is unreasonable, a high spike voltage is likely to occur and render power electronic components easily to be damaged and threatens the safe operation of equipment. In this paper, a new optimization design method of RC snubber circuit is proposed for thyristor in high-capacity AC-DC converter, more accurate R and C parameters and resistor power is deduced, and its reliability is improved as a result. Simulations and experiments are carried out to verify the feasibility and viability of the method.