A general method for reliability sensitivity analysis and reliability optimization design of planar slider crank mechanism with two clearance joints was presented. A continuous contact force model considering energy dissipation was employed to estimate the contact force acting on the clearance joint. The Monte Carlo method was used to analyze the reliability sensitivity. In addition, based on the Kriging method, a surrogate model was constructed with consideration of explicit function expression. The precision and reliability of the presented method have been successfully demonstrated by numerical simulation. The results show that the number and position of clearance joint considered have a great influence on the maximum allowable displacement of the slider. The changing of the reliability sensitivity for the mean and variance of several random variables has certain regularity. Compared with the determinacy optimization design, the reliability optimization design presented here shows better dynamical performances.

In order to construct the voltage‐sourced converter high‐voltage direct current grids, the high capacity direct current circuit breakers (DCCBs) are in demand. The hybrid DCCB has been the mainstream proposal, where the high‐voltage solid‐state switch (HVSS) is the key component for breaking the final fault current. Investigating the current commutation between the breaking branch and energy‐absorbing branch, a hybrid DCCB with repositioned current commutation module (CCM) and redesigned HVSS is proposed in this study. By analysing the equivalent circuit of the CCM and HVSS, the detailed transient stages during current interruption procedure have been revealed, and the comparisons of different topologies for HVSS are made in‐depth. The repositioned CCM can greatly decrease the transient voltage stress for HVSS and CCM whilst the improved HVSS including metal oxide varistor can maintain better interruption performances. Then the actual prototypes are developed to verify the effectiveness of the improved hybrid DCCB topology. In the end, a 500 kV DCCB is realised based on the proposed HVSS, which can ensure the reliability and convenience of the hybrid DCCB.