A novel approach for determining temperature in an appliance without using a sensor

An electronic control design is described which approximates the temperature of a heating element without measuring it. Because no sensor or closed-loop electronics are utilized, and because the control uses the same circuits and ROM of an existing electronic control system, the incremental cost is zero. The control system monitors the power setting selected by the user and then utilizes an electronic counter (called the heater energy counter), which is incremented or decremented at a rate that is approximately proportional to the rate of increase or decrease of temperature of the heating element for that power setting. By knowing the user setting and counting zero crossover points, the raw power into the heating unit is determined, and by empirically determining the thermal losses for different power levels, the effective energy in the heating unit is determined.<
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