Kenneth Frogner

Induction heating using a 2-phase travelling wave setup

Abstract in Undetermined A laboratory implementation of a two-phase travelling wave induction heating setup is described. The focus is the development of a versatile power control system for multi-coil experiments and parameter studies. The drive system features high temporal accuracy, full real-time controllability, and integrated measurement technology, analyzed step wise. The performance was tested using a full pitch travelling wave inductor based on litz wire with a flux concentrator from a powder material. Thermographic images from the experiments are presented and the results are compared with simulations. The challenges related to multi-coil configurations are explained, many of which are difficult to predict from simulations. (Less)

Induction heating of carbon fiber composites: Investigation of electrical and thermal properties

Carbon fiber reinforced plastics, CFRP, are attractive materials not only because of their strength and stiffness but also because of their electrical conductivity and high thermal conductivity and diffusivity. One application where induction heating of CFRP is particularly interesting is tools for fast thermal cycling, beneficial in many industrial processes, for example in composite manufacturing. The electrical properties make it possible to heat with induction and the high thermal conductivity allows fast heat equalization. In order to control inducting heating of CFRP it is desirable to know the electrical and thermal properties of the composite. This work presents developed experimental methods that are used in an investigation of how the thermal and electrical properties of CFRP structures are affected by the fiber properties and composite structure. The experiments and simulations show that fiber type and fiber volume fraction are of great importance for the electrical and thermal properties. The relation between fiber volume fraction and equivalent resistivity is nonlinear and the experiments indicate that a fiber volume fraction exceeding 60% is necessary to achieve a fairly isotropic resistivity and uniform induction heating pattern.

Alternative production process for electric machine windings

The development of production methods, research on material engineering and analysis tools for energy conversion processes establish a powerful design environment for any unconventional electromagnetic or electromechanical device. The design for manufacturability becomes the one of the main goals of the design apart from cost and performance improvement. The main focus of this paper lies on the development of production methods, the design of the product, a wave-winding, and the component assessment in an electrical machine. The production of non-complex coil with maximized performance capability of the molded core machine is the target for the design of the winding and also the design for the winding machine. Four different types of wave-windings are described and evaluated. One of them, wind and bend with conventional wire, has main focus in this work, and a prototype of the winding machine is built to produce the single-layer whole-lap wave-winding. The production method, manufacturing process and the processed component features are analyzed in this paper.

Mapping of magnetic properties for simulations of high-Temperature electromagnetic applications

Purpose The purpose of this paper is to investigate the added value of using temperature-dependent electric and magnetic properties in high-temperature electromagnetic simulations. Design/methodology/approach In this work, the electromagnetic properties of Domex 420, SSAB, have been characterized as a function of the temperature, from room temperature to 900°C. The measurement of the electric and magnetic properties was performed inside a vacuum furnace at a number of discrete temperature steps, with particularly small intervals around the Curie temperature. A simple transient multi-physics model was used to investigate the impact of the measured properties in three different representations. Findings In certain intervals, a simplified approximation of the properties produces accurate results, while fully parametric representation is beneficial when heating above the Curie temperature. Originality/value Temperature-dependent electromagnetic properties are rarely found, especially in an easy-to-use form. Using parameterized temperature-dependent approximation of key properties shows noteworthy differences in the outcome of high-temperature electromagnetic modeling.