A methodology for accurate simulation of movable parts under the influence of electromagnetic forces

摘要

Many devices, for example contactors and solenoid actuated valves, rely on ferromagneticudcomponents moving under the influence of electromagnetic force for their operation. Theudpopularity of this technology stems from the fact that it is an elegant, cost effective andudrobust way to convert electrical energy into mechanical work. From a product design pointudof view it is very important to quantify the magnitude of the electromagnetic force and toudpredict the behaviour of ferromagnetic components under the influence of this force. Inudmost cases these forces are estimated by means of first order calculations or Finite ElementudMethods. It is plausible, as this dissertation shows, that direct measurement can be used toudreplace or supplement theoretical methods to obtain these forces. However, limitedudprevious work describing methods and techniques for the measurement of theseudelectromagnetic forces, are available in the public domain. In general, prior work in thisudfield [12] is very specialised and limited with respect to the range of forces that can beudmeasured, and not easily adaptable to a product design environment.udThis thesis proposes a novel piece of equipment for the measurement of electromagneticudforces acting on ferromagnetic components, and a method to predict product performanceudbased on these measurements.udThe measurement equipment, and product performance prediction, is described andudevaluated for the case of low voltage hydraulic magnetic circuit breakers.udLow voltage hydraulic magnetic circuit breakers are a particularly interesting subject as itudcontains one source of electromagnetic force acting on two ferromagnetic components.udThe two ferromagnetic components have different equations of motion, with dramaticallyuddifferent damping coefficients. A further complication in the operation of hydraulicudmagnetic circuit breakers is that these ferromagnetic components can move separately orudsimultaneously. The motion of the components is influenced by the magnitude of theudapplied electromagnetic force and their position relative to each other. Low voltageudhydraulic magnetic circuit breaker performance is subject to the combined motion of theseudtwo ferromagnetic components.udThis work concludes that the method for measuring electromagnetic forces with the aim ofudpredicting device performance is feasible, and that it produces good results whereudelectromagnetic forces need to be known to high accuracies.