Vessel Temperature Estimation Method using Equivalent Resistance Difference

As a method of estimating the temperature of the vessel, an indirect method by NTC resistance and direct measurement by infrared sensor have been proposed. However, they cause poor temperature estimation accuracy and increase the cost of the entire system. In this paper, a vessel temperature estimation method based on resistance difference is proposed. The proposed method uses the correlation of the resonant network related to switching frequency and temperature. The resistance difference is obtained by changing the switching frequency instantaneously and by subtracting the estimated equivalent resistance value at each switching frequency. Since the induced resistance difference can minimize the influence of the coil's temperature, it is possible to accurately estimate the vessel's temperature only. The validity of the proposed method is verified by using a 1.2-kW half-bridge series resonant inverter prototype.