Design and optimization of vacuum circuit breaker operating mechanism considering reclosing based on electromagnetic repulsion mechanism and semi-hard magnetic actuator

The dynamic characteristics and reliability of an operating mechanism directly influence the breaking performance of a vacuum circuit breaker. To achieve two rapid opening operations and one closing operation under reclosing conditions, and to enhance overall performance, a novel operating mechanism integrating an electromagnetic repulsion mechanism (ERM) with a semi-hard magnetic actuator (SHMA) is proposed. Comprehensive multi-objective optimization, along with simulation and experimental studies, has been conducted. A SHMA suitable for holding and closing operations is introduced, and its static and dynamic characteristics are analyzed and compared with those of a permanent magnetic actuator (PMA). For the multi-objective optimization of the structural parameters of the repulsion disk and coil, a combined approach using response surface methodology (RSM) and the non-dominated sorting genetic algorithm II (NSGA-II) is employed. The results indicate that the SHMA reaches steady state more rapidly, achieves higher closing speed, and exhibits reduced rebound compared to the PMA. Furthermore, the ERM demonstrates reduced current, peak mechanical stress, and radial dimensions, offering valuable guidance for engineering applications.