The invention relates to a method for operating an ignition device for an
internal combustion engine, which ignition device is formed with an
ignition coil (ZS) which is configured as a
transformer, a
spark plug (ZK) which is connected to the secondary winding of the
ignition coil (ZS), an actuable switching element (IGBT) which is connected in series to the primary winding of the
ignition coil (ZS), and a
control unit (SE) which is connected to the control input of the switching element (IGBT), wherein the
control unit (SE) provides an adjustable supply
voltage (Vsupply) for the ignition coil (ZS) and an actuating
signal (IGBT_Control) for the switching element (IGBT) as a function of the currents (I_Prim, I_Sec) through the primary and the secondary windings of the ignition coil (ZS) and the
voltage between the connecting point of the primary winding of the ignition coil (ZS); to the switching element (IGBT) and the negative terminal of the supply
voltage (GND), as a result of which firstly operation of the
spark plug (ZK) by way of
alternating current is possible and secondly regulation of said current is possible, which leads to more reliable ignition with a lower wear of the spark plugs.