Research On Topology Design And Optimization Method Of Novel Electromagnetic Mechanisms

One of the key technical foundations of developing smart grid is intelligentized high voltage apparatus, among which the intelligent operation of circuit breakers is mounting more and more urgent demands for preferable speediness and controllability of the electromagnetic mechanisms, and this relies much on topology design and optimization method of novel electromagnetic mechanisms. As regards the state-of-the-art development all over the world, it has rarely been seen systematic research work on topology design and optimization that incorporates both aspects of speediness and controllability of the electromagnetic mechanisms. Starting with topology design, this dissertation concentrates on four novel type electromagnetic mechanisms, and comprehensive methodology is presented to realise topology design and optimal analysis, which establishes both theoretical and technological basis for developing novel electromagnetic mechanisms.Theoretical analysis is firstly done regarding the disc-type repulsive fast mechanism, and a dynamic model is deduced based on the coupling interaction between single-turn coils, further, a discrete iterative algorithm is proposed based on double-layer iteration of time and displacement, which can be utilised in the simulation analysis and integrated optimization of the disc-type repulsive mechanism. But for instantaneous controllability of the electromagnetic mechanism, these mathematical models and algorithms are still relatively complicated in practice.Many mature control strategies being available for nowadays rotating motors, a permanent magnet motor based control scheme is put forward for possible operation mechanism of circuit breakers. With analysis on the correlation between rotating angle and line displacement, also with integration of PID and single-neutron control methodologies, a control strategy for speed tracking of the mechanism's moving process is presented, which provides referential method for realising flexible controllability of the mechanism. However, due to relatively large electromagnetic inertia of the motor and mechanical inertia of the drive element, it is to some extent difficult to achieve speediness of the mechanism.In order to incorporate the advantages of both electromagnetic mechanisms described above, a new mechanism, namely motor coil based repulsive electromagnetic mechanism, is proposed with a view to achieving both speediness and controllability. Here, utilization of permanent magnet with small relative permeability lowers the loop circuit inductance, and adoption of the symmetrical and differential compensation structure maintains a roughly invariable equivalent inductance during the moving process of the mechanism, which gives a preferably simplified analysis model. Based on both electromagnetics and mechanical dynamics, an equivalent controlled voltage source is used to present the complicated coupling relationship between the electromagnetic and mechanical characteristics of the mechanism, which gives a new route to address the decoupled analysis and control issue of electromagnetic mechanisms. The PSIM software is used to establish a PWM-based simulation model for speed tracking control, and the results demonstrates that, with power electronics devices and PWM control, it is feasible and effective to achieve roughly zero collision bounce of the mechanism during its switching operations, which presents methodologies for speed control to track a given optimal movement curve of circuit breaker mechanisms. However in the meantime, adoption of iron core and permanent magnet within the mechanism increases nonlinear behaviour of the mechanism, which creates difficulty in guaranteeing control accuracy.To counteract the disadvantages of the nonlinear magnetic materials, and also with consideration of the design requirements from controllability being imposed to electromagnetic mechanism topology, a novel reversely wound and nested solenoid type electromagnetic mechanism is proposed for further investigations. The mechanism is composed of both fixed and moving coils, but without any iron core or permanent magnet. With detailed analysis on the transverse component distribution of the coils' magnetic fields, an interaction coefficient is presented to describe coupling features of the mechanism. Given the mechanism topology, the interaction coefficient is constant, which to great extent will simplify the mathematical model and thereby facilitate controllability of the mechanism. A prototype model of the novel mechanism is designed, further with simulations and experimental studies being carried out.Owing to diversity of the electromagnetic mechanisms in both topologies and analysis methodologies, it is much often to use static indexes to evaluate the performance of traditional electromagnetic mechanisms, with very few evaluation specifications with regards to the dynamic characteristics of electromagnetic mechanisms. Based on the fundamental equations of electromagnetics, this dissertation puts forward a definition of magnetism sensitivity coefficient to quantitatively appraise the varied impacts of driving current on the coulomb forces, and also to evaluate the controllability of a mechanism's movement. In terms of materials, topologies and magnetism sensitivity, comparative analysis is carried out regarding to three types of electromagnetic mechanisms, which indicates that, a mechanism with large and also invariable magnetism sensitivity coefficient will foresee prospective advantages in both aspects of speediness and controllability. Further, the topological correlation between the disc-type repulsive mechanism and the reversely wound and nested solenoid type mechanism is studied in details, which shows that both are derived topological configuration from the single-turn coil respectively thorough radial and longitudinal extension, and the magnetism sensitivity coefficient of the former roughly doubles that of the latter one. From the topology point of view, this kind of analysis provides a new route being directed to topology study for developing prospective electromagnetic mechanisms.