A measurement method for the characterization of the ferromagnetic bottom layer of cookware used in domestic induction heating

Abstract

Design-oriented modeling approaches, such as finite element analyses (FEA), rely on accurate material data. However, manufacturers rarely provide the necessary data for cookware used in domestic induction heating. Due to the multi-layered structure of the cookware bottom, conventional measurement methods for the characterization of magnetic material are not applicable without great effort in preparation of suited material specimen. This contribution proposes a novel measurement method that allows determining the electromagnetic properties of the ferromagnetic bottom layer of cookware. The proposed measurement method is based on the minimization of deviation between measurement and simulation data in dependence of material properties. By characterization of the ferromagnetic bottom layer of a material specimen made from multiple layers, the feasibility of the method is shown. The results presented for the magnetic material characterization are validated using Epstein frame measurements. It is shown that the deviation between the magnetization curve determined with the proposed method and the tip of the hysteresis curve measured using the Epstein frame is approximately 3 %. To validate the results presented for the specific electrical resistance, a microhmmeter is used. The relative error between both measurements is approximately 16 %.

A Non-Resonant Multi-Output Half-Bridge Inverter for Flexible Cooking Surfaces

“…The litz wire has n s = 600 strands with a diameter of d s = 71 μm of a single strand. The material parameters of the ferromagnetic bottom of the pot are taken from [15].…”

“…The litz wire has n s = 600 strands with a diameter of d s = 71 μm of a single strand. The material parameters of the ferromagnetic bottom of the pot are taken from[15].The values of L eq and R eq for a single inductor beneath a pot in dependence of the effective current through the inductor I L and its frequency f is shown in Fig.4and Fig.5. In Fig.4it can be seen, that the equivalent inductance L eq is decreasing with increasing values of inductor current I L and frequency f .…”