Boil dry detection in cooking appliances

摘要

Boil dry conditions are detected in utensils heated on a cooking appliance having at least one energy source disposed under a cooking surface such as a glass-ceramic plate and a controller for controlling the level of power supplied to the energy source. The boil dry detection system includes a temperature sensor for providing a signal representative of the glass-ceramic temperature to the controller. The controller controls the power source in response to the temperature signal so as to prevent the glass-ceramic plate from exceeding a maximum temperature and provides a power signal that is indicative of the level of power being supplied to the energy source. The controller generates an estimate of the first and second derivatives with respect to time of either the temperature signal or the power signal, depending on its operating mode. The controller then produces the cross-correlation of the first and second derivative estimates and provides a boil dry indication when the cross-correlation exceeds a predetermined threshold. In one preferred embodiment, the portion of the controller that generates the derivative estimates is implemented as two Kalman filters.