Research On Bi-stable Permanent Magnetic Actuator Of Low Voltage Vacuum Circuit Breaker

The low voltage circuit breaker is not only an important product of low voltage electrical appliances,but also the key equipment of distribution network.The security and reliability of the system is directly related to the user's experience and the stability of the power grid.The research conclusion is based on bi-stable permanent magnetic actuator(PMA)of the low voltage vacuum circuit breaker(VCB).Compared with other types of circuit breakers,it has many incomparable advantages,such as its simple structure,high reliability,low energy consumption,intelligent and etc.With the development and perfection of the technology of the vacuum interrupter and PMA,it implements the application of PMA in the low voltage VCB.The structure and working principle of the PMA is described.Firstly,the advantages and disadvantages of bi-stable and monostable permanent magnetic mechanism are compared and analyzed.Then the characteristics and working principle of the PMA is analyzed.The software of finite element method(FEM),the electromagnetic field and the basic theory of Taguchi method are introduced,which provides a powerful research method for the optimal design of the PMA.Finally,the cylindrical bi-stable PMA is selected as the operating mechanism of the low voltage VCB.The size of bi-stable PMA is preliminarily designed,mainly grounding on the analysis of the equivalent magnetic circuit about the bi-stable PMA and the methods of electromagnetic system design.The size of each component of the bi-stable PMA was calculated,the simulation model of bi-stable PMA is modeled and simulated in FEM software by using above all the methods.The initial design dimensions content the design requirements by analyzing the simulation results.It proves that the mechanical properties of the low voltage VCB are basically content the mechanical properties of the preliminary design.The overall performance of bi-stable PMA is optimized.Firstly,the structure of bi-stable PMA is optimized by using the Taguchi method,and the results are analyzed.And the design of the excitation coil is also optimized.what's more,a capacitor parameter optimization algorithm is proposed.Then the rationality and accuracy are verified by simulation and calculation.Finally,the performance of the bi-stable PMA is tested and verified by producing test prototype,planning suitable experimental program,building the experimental platform.It proves that the optimized structure is reasonable and feasible.