Analysis of structure strength in medium voltage DC system high speed repulsing mechanism

High speed repulsion mechanism is the key component of Hybrid DC circuit breaker, whose properties and reliability directly determine whether the fault short-circuit current can be quickly broken off. The driving force, produced by the eddy current effect, reach tens of kilo Newton in 100μs, which means the huge impact on motion component. Due to its characteristics, it is necessary to check the strength of the stressed components and optimize the structure of the mechanism. The traditional static stress solution method does not take into account the influence of the acceleration and inertia force of the motion components, while they have crucial affects on stress distribution. In this paper, based on flexible body dynamics, three-dimensional finite element model is established. The dynamic stress distribution of each component is solved under the given driving circuit parameters, and an improved structural scheme is proposed according to the simulation result. Finally, an experimental prototype is built, and the life test results of the repulsion mechanism validate the simulation results.