Importance

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Abstract

An exciter circuit for firing one or more igniter plugs in an aircraft ignition system. The exciter circuit includes an input node capable of receiving an alternating-current (AC) voltage with a variable frequency and amplitude, a pair of tank capacitors used as energy storage devices, a charging circuit for charging the tank capacitors, a discharge circuit for providing spark energy from the capacitors to two igniters, and a spark gap to initiate the discharge once the capacitors have been charged to a sufficient voltage. The charging circuit includes a step-up ferro-resonant transformer network and a full-wave rectifier. The transformer network includes a saturating transformer, a choke coil in series with the transformer primary, and one or more tuning capacitors connected to a center tap on the primary. The relative values of inductance of the choke coil and transformer primary and the capacitance of the tuning capacitors is set to provide a resonant frequency that is equal to the nominal frequency of the AC input power. The transformer primary is designed to saturate during normal operation. With this arrangement, the exciter exhibits good regulation of input current and spark rate over a wide range of input amplitudes and frequencies.

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First Claim