Method and an apparatus for controlling glow plugs in a diesel engine, particularly for motor-vehicles

An apparatus for controlling a glow plug associated with a cylinder chamber of a diesel engine, comprising:

• an electronic switch connected essentially in series with the glow plug between terminals of a D.C. voltage supply;
• a sensor adapted to provide a first analog sense signal and a second analog sense signal representative of a current flowing through the glow plug and a voltage across the glow plug;
• and
• an electronic controller coupled to a control input of the electronic switch and to the sensor, the electronic controller adapted to:
• drive in an on-off manner the electronic switch;
• generate the first analog sense signal that is representative of a first time integral of a sensed current;
• generate the second analog sense signal that is representative of a second time integral of a sensed voltage;
• generate a first reference signal having a first analogue value corresponding to a value of a first digital control word;
• generate a second reference signal having a second analogue value corresponding to a second digital control word;
• compare, while the electronic switch is in an on-state, the first analog sense signal and the second analog sense signal with the first reference signal and the second reference signal;
• modify a digital value of the first digital control word and the second digital control word to minimize a difference between the first analog sense signal and the second analog sense signal and the first reference signal and the second reference signal;
• and
• calculate an average value of the sensed current and the sensed voltage over a period of time, as a function of the difference between the value of said first digital control word and the second digital control word at a beginning and at an end of the on-state or a conduction time of the electronic switch.