Optimal Design Of Monostable Permanent Magnet Operating Mechanism Of DC Magnetic Field Circuit Breaker

The excitation winding of the generator is equivalent to a large energy storage inductance.When the excitation current changes suddenly due to cut-off,it will produce a transient overvoltage,which poses a threat to the insulation of the generator winding.Therefore,the magnetic energy in this process must be consumed quickly.The field circuit breaker plays an important role in cutting off the current in the de-excitation system,and the operating mechanism is the key component of the field circuit breaker.Therefore,according to the characteristics of different types of operating mechanisms and the technical parameters and requirements of magnetic field circuit breaker,the double coil monostable permanent magnet operating mechanism is selected as the operating mechanism of the magnetic field circuit breaker.A series of studies are also carried out in this thesis on the reaction force characteristics considering friction and the optimal design of the operating mechanism.Firstly,the structural characteristics and working principle of monostable permanent magnet operating mechanism are proposed in this thesis.Combined with the equation of electromagnetic field and motion equation,the solution method of static and dynamic characteristics of the mechanism is given,and the mechanism is analyzed theoretically.Secondly,the design experience of monostable permanent magnet operating mechanism of magnetic field circuit breaker is given,and the reaction force characteristics of transmission mechanism considering friction is mainly studied,so that the accuracy of finite element simulation calculation of dynamic characteristics of operating mechanism is improved,and the important parameters required for subsequent optimization are obtained.The appropriate experimental equipment is selected to build an experimental platform to obtain the opening and closing coil current curve and moving core displacement curve of the mechanism,which are compared and verified with the simulation results considering friction.Finally,the material and wire diameter of the original mechanism are improved.Taking the opening time and energy conversion efficiency of the opening coil as the optimization objectives,the closing time and energy conversion efficiency of the closing coil as the constraint objectives,and the mechanism volume and closing holding force as the constraint conditions,the Taguchi method is used to optimize the dimension parameters of the mechanism.Based on the influence of the dimension parameters of each part on the electromagnetic suction,five parameters are selected as the optimization variables,and the optimal parameter level combination meeting the target requirements is obtained through four level orthogonal experiment.The optimized mechanism not only greatly improves the performance,but also meets the development trend of mechanism miniaturization.