Patent ID: 8115144

Claim:
A method of controlling, in a Diesel internal combustion engine, an operation of a glow-plug (GP) that is driven with a pulse-width-modulated voltage (VPWM) applied thereto, the method comprising the steps of: detecting a glow-plug voltage (VGP) and a glow-plug current (IGP); sensing a number of predetermined engine and environmental input variables comprising an engine speed (ωE), an engine temperature (TE), and an ambient air temperature (TA); and varying a duty-cycle (DC) of the pulse-width-modulated voltage (VPWM) applied to the glow-plug (GP) in dependence upon the glow-plug voltage (VGP) and the glow-plug current (IGP) and sensed values of the environmental input variables, wherein an actual current temperature (TGP,est) of the glow-plug (GP) is estimated in accordance with a first predetermined model of the glow-plug (GP) in a corresponding combustion chamber as a function of detected values of the glow-plug voltage (VGP) and the glow-plug current (IGP) and the sensed values of the environmental input variables, wherein at least one of the glow-plug voltage (VGP,des) or an electrical power (PGP,des) to be supplied to the glow-plug (GP) is determined in accordance with a second predetermined model of the glow-plug (GP) in a combustion chamber as a function of an estimated temperature (TGP,est) of the glow-plug (GP), and the sensed values of said environmental input variables, and wherein the duty-cycle (DC) of the pulse-width-modulated voltage (VPWM) applied to the glow-plug (GP) is varied in a predetermined manner as a function of a calculated value of at least one of the glow-plug voltage (VGP,des) or a power (PGP,des) to be supplied to the glow-plug (GP).