A methodology for accurate simulation of movable parts under the influence of electromagnetic forces
Date
2010-03-29T12:11:32Z
Authors
Van Staden, Christian Olivier
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Abstract
Many devices, for example contactors and solenoid actuated valves, rely on ferromagnetic
components moving under the influence of electromagnetic force for their operation. The
popularity of this technology stems from the fact that it is an elegant, cost effective and
robust way to convert electrical energy into mechanical work. From a product design point
of view it is very important to quantify the magnitude of the electromagnetic force and to
predict the behaviour of ferromagnetic components under the influence of this force. In
most cases these forces are estimated by means of first order calculations or Finite Element
Methods. It is plausible, as this dissertation shows, that direct measurement can be used to
replace or supplement theoretical methods to obtain these forces. However, limited
previous work describing methods and techniques for the measurement of these
electromagnetic forces, are available in the public domain. In general, prior work in this
field [12] is very specialised and limited with respect to the range of forces that can be
measured, and not easily adaptable to a product design environment.
This thesis proposes a novel piece of equipment for the measurement of electromagnetic
forces acting on ferromagnetic components, and a method to predict product performance
based on these measurements.
The measurement equipment, and product performance prediction, is described and
evaluated for the case of low voltage hydraulic magnetic circuit breakers.
Low voltage hydraulic magnetic circuit breakers are a particularly interesting subject as it
contains one source of electromagnetic force acting on two ferromagnetic components.
The two ferromagnetic components have different equations of motion, with dramatically
different damping coefficients. A further complication in the operation of hydraulic
magnetic circuit breakers is that these ferromagnetic components can move separately or
simultaneously. The motion of the components is influenced by the magnitude of the
applied electromagnetic force and their position relative to each other. Low voltage
hydraulic magnetic circuit breaker performance is subject to the combined motion of these
two ferromagnetic components.
This work concludes that the method for measuring electromagnetic forces with the aim of
predicting device performance is feasible, and that it produces good results where
electromagnetic forces need to be known to high accuracies.