Control of an induction heat treatment by the measure of power

The authors investigate a way to control the induction heating processes through the measurement of the instantaneous active power transferred to the component. They first model the process using 2-D and 3-D (computer-aided design packages), and then compare the results of the computation to the measurement of the power used in the actual process. The 3-D magnetothermal problem with a moving source is solved through the combined use of different modeling tools (2-D finite-element and 3-D boundary-element programs). Measuring the active power transferred by the coil is an efficient way to detect changes in the shape of components being heat treated with a scanning coil. It gives accurate measurements and does not require any modification of the process itself. The power measurement can be used to control the power supplied to the coil, the linear displacement of the component, and eventually displacements of the coil in order to correct the coupling