Patent ID: 8025040

Claim:
A plasma ignition system comprising: a plasma-discharge ignition plug; an ignition coil that supplies a discharge voltage to the ignition plug based on an ignition signal; and a plasma power supply circuit that is connected in parallel to the ignition plug and supplies electric energy for generation of plasma into a discharge space of the ignition plug at a start of discharge of the ignition plug, wherein the plasma power supply circuit includes a plasma jet capacitor that is connected in parallel to the ignition plug and supplies the electric energy for discharge and generation of the plasma in the discharge space of the ignition plug at the start of discharge of the ignition plug, a DC/DC converter that is connected to a direct-current power supply and outputs a direct-current voltage for charging of the plasma jet capacitor, and a voltage-limiting circuit having a first set voltage having an absolute value lower relative to the discharge voltage of the ignition coil, and a second set voltage having an absolute value higher relative to the discharge voltage of the ignition coil, and wherein the first set voltage and the second set voltage are selectively switched according to an operation condition of an internal combustion engine.