Method and device for detecting the breakdown voltage between the electrodes of a spark plug connected to an ignition coil for a cylinder ignition system in an internal combustion engine

A device for detecting a breakdown voltage between electrodes of a spark plug connected to an ignition coil for a cylinder ignition system in an internal combustion engine, said coil comprising a primary winding and a secondary winding, wherein:

• the primary winding is connected to a voltage generator and is provided with a switch that can be switched between an open condition and a closed condition to initiate a breakdown and spark at the spark plug;
• the secondary winding is connected to the spark plug;
• said device comprising:
• a primary voltage detection module configured to detect a voltage on the primary winding and generate a first signal representative of said voltage;
• an identification module configured to detect an occurrence of the breakdown at said spark plug and to generate a breakdown signal representative of said breakdown, wherein said identification module comprises:
• at least one current detection member on the secondary winding configured to generate a second signal representative of a current flowing in the secondary winding;
• at least one comparison unit comparing said second signal with a predetermined threshold value, wherein said breakdown signal is generated in a breakdown instant in which said second signal exceeds said threshold value;
• a processing module operatively connected with said detection module and said identification module and configured to:
• receive an opening signal representative of the switching of the switch from said closed to said open condition;
• receive said first signal;
• receive said breakdown signal;
• integrate over time a value of said first signal in a time interval running after receiving said opening signal to generate an integrated signal increasing over time in said time interval;
• determine a breakdown value of said integrated signal upon receiving said breakdown signal;
• determine a breakdown voltage value as a function of the breakdown value of the integrated signal at the breakdown instant representative of the breakdown.