Design Of Improved Monostable Permanent Magnetic Actuator For Low Voltage Vacuum Circuit Breaker

Low voltage circuit breaker is used to break and protect the main circuit in low voltage power distribution system.The safe and stable operation of power system is related to the safety and reliability of low voltage circuit breaker.The performance of low voltage circuit breaker is mainly influenced by the operating actuator.Application fields of low voltage circuit breakers is mainly influenced by the arc-extinguishing chamber.With the technical progress of vacuum arc-extinguish chamber and the further development of rare earth materials,the vacuum circuit breaker based on the permanent magnetic actuator began to develop in the direction of miniaturization and low voltage.The working principle and advantages and disadvantages of three kinds of permanent magnetic actuator is analyzed.According to the characteristics in the field of low-voltage,the monostable permanent magnetic actuator is selected as the research object.On the base of technical parameters and the required mechanical properties of the low voltage vacuum arc-extinguish chamber,parameters of monostable permanent magnetic actuator is overall designed.Combining with the working principle and movement characteristics of monostable permanent magnetic actuator,an improved monostable permanent magnetic actuator is presented.Dynamic and static properties’ simulation analysis of 2D and 3D of improved monostable permanent magnetic actuator is carried out by using finite element analysis software.The analysis of simulation results show that the improved magnetic actuator conforms to the required mechanical properties of the vacuum arc-extinguishing chamber,and has practical feasibility.According to the comparison of simulation analysis of improved and traditional monostable permanent magnetic actuator,improved actuator required less permanent magnetic materials under the circumstances of the same permanent magnet holding force.The closing characteristic basically unchanged but the opening time is shorter and speed is faster.Establishing the objective function of minimum total volume of optimization model and selecting the appropriate optimization variables and constraints,the optimization of the whole structure of the improved permanent magnetic actuator is carried out by using genetic algorithm.The volume decreased 15.3% after optimization.The optimized actuator is carried out dynamic simulation analysis,which concludes that various performance of the optimized actuator has a certain improvement.According to build the experimental platform,the feasibility of the improved permanent magnetic actuator is verified by measuring the switching velocity of the low voltage vacuum circuit breaker.The results show that the improved actuator is consistent with the mechanical characteristics of the vacuum arc extinguishing chamber.