Research On Optimization Design Of Permanent Magnetic Actuator For Vacuum Circuit Breaker

Due to the relatively small number of mechanical parts, high reliability, less maintenance, the perfect match with the vacuum circuit breaker (VCB) and many other advantages, permanent magnetic (PM) actuator draws great attention from countries all over the world.The significance and purpose of the PM actuator optimization design is introduced in the beginning of this paper, and then the development of optimization method, PM actuator and inverse problem of electromagnetic field are discussed. In the part of optimization method, the improvement project of simulated annealing algorithm (SAA) is brought forward, in which combine SAA with Genetic Algorithms (GA) and added the idea of niche, come out a Niched Genetic Simulated Annealing Algorithms (NGSA), testing and comparing is done to prove its high ability of optimize through the calculation of some universal functions. In the part of electromagnetic field calculation, the static and dynamic models of the non-linear magnetic field calculation for PM actuator under the two different excitation circuits are set up based on the theory of finite element, and boundary conditions are confirmed. In addition, permanent magnet is simulated with surface current method. Numerical calculating method in this paper is expatiated. In the part of dynamic computing of PM actuator, the kinematic equation to solving current i is given in order to avoid reiteration in the solving of magnetic linkage Ψ, and according the course of movement on PM actuator, it is divided into two different phases to be solved using the four-order Runge-Kutta method. Using the NGSA to optimize a 40.5kV cylindrical bi-stable PM actuator, a multiobjective mathematical optimization model whose objective functions are the cumulative volume of PM actuator and the volume of permanent magnet is set up, choose appropriate optimize variables and constraint conditions. From the result, it can be seen clearly that both cumulative volume and the cost of the PM actuator are greatly reduced. A dynamic simulation of the optimum result is done, and a new model machine is developed. The testing of VCB with the new model machine after optimized is done, and itshows that the performance index of VCB is satisfied, so both the feasibility of the optimization method and the result of the optimization are verified.