Patent Document ID: 8972075
Application ID: 12784070
Patent Flag: 1

Claim One:
1. A method for closed-loop controlling the temperature of a glow plug, wherein a) a setpoint temperature is used to determine a setpoint value of a temperature-dependent electric variable, and b) an effective voltage which is generated by pulse width modulation is applied to the glow plug, wherein c) a mathematical model comprising a linear differential equation, which calculates an output variable from an input variable and provides the output variable at its output, is used to calculate an expected value of the temperature-dependent electric variable, d) a measured value of the temperature-dependent electric variable is measured, e) a first error signal is generated by comparing the calculated expected value of the temperature-dependent electric variable with the measured value of the temperature-dependent electric variable, f) value calculated from the effective voltage and the first error signal is used as a new input variable of the mathematical model, wherein the mathematical model calculates a new output variable from the new input variable, said new output variable defining a new expected value of the temperature-dependent electric variable, and g) the new output variable of the mathematical model and the setpoint value of the temperature dependent electric variable are used to calculate a corrected value for the effective voltage and the effective voltage is changed to the corrected value thereby controlling the temperature of the glow plug, h) wherein the closed-loop controlling method repeats itself starting at step d.