Round Billet Mold Temperature Measurement Data Analysis And Filtering Method

It's very important of accurate, reliable on-line temperature measurement of the mold during the continuous casting manufacture. It is because the thermocouples are installed in alternating magnetic field of the electromagnetic stirring (EMS) that measured temperature has been gotten strong interference; therefore it's necessary to filter the influence of EMS.The improved direct method-Welch method used in this paper to estimate the power spectral of measured temperature, and the frequency characteristics of the actual temperature and interference signal in measured temperature are taken, forth more institutes the design performance characteristic of filter. Because the filter effects with filter methods for the measured temperature are unsatisfied, this paper adopts the low-pass finite impulse response (FIR) digital filter with linear phase to deal with measured temperature. MATLAB has been used to simulate and study several FIR digital filter design methods, the results show that the filter designed with Chebyshev equripple approximation is the optimal under the given performance characteristic.The Chebyshev filter has been used to filter measured temperature in different EMS current and frequency conditions, the result indicates that the filter has fast computation speed and narrow transition band. Satisfied effect of EMS interference rejection has proved.