Ignition system

An ignition system for an internal combustion engine comprises an ignition transformer with two primary windings (L P1 , L P2 ). The ignition system is designed to generate, for a given ignition event, a unipolar current (I SEC ) through the secondary winding (L SEC ) by way of a control circuit (20) that is configured to first energize and deenergize the first primary winding (L P1 ) to establish a first electrical arc across the spark-plug electrodes (14) and, when the current (I SEC ) in the secondary winding reaches, or drops below, a current threshold (I SEC_TH ), repeatedly energizes and deenergizes the second primary winding (L P2 ) to establish a plurality of second current pulses across the electrodes in order to maintain the burn phase.