Inductive start and capacitive sustain ignition exciter system

Abstract

An ignition exciter system includes an igniter, a step-up transformer, a switch device, and a spark-sustain capacitor. The igniter has a spark gap across which a spark may be generated. The step-up transformer has a primary winding that is adapted to selectively receive direct current (DC) from a DC source, and a secondary winding that is coupled to the igniter. The switch device is coupled to the primary winding and is configured to selectively operate in an ON state, in which DC may flow through the primary winding, and an OFF state, in which DC may not flow through the primary winding. The spark-sustain capacitor is coupled to the igniter and is configured to charge from a DC source when the switch device is operating in the ON state, and at least selectively discharge across the spark gap when the switch device is operating in the OFF state.

What is claimed is: 
     
         1 . An ignition exciter system, comprising:
 an igniter having a spark gap across which a spark may be generated;   a step-up transformer having a primary winding and a secondary winding, the primary winding coupled to receive direct current (DC) from a DC power source, the secondary winding coupled to the igniter, the step-up transformer configured to at least selectively generate a voltage at the secondary winding that is sufficient to generate a spark across the spark gap;   a first switch device coupled to the primary winding and configured to selectively operate in an ON state, in which DC may flow through the primary winding, and an OFF state, in which DC may not flow through the primary winding;   a second switch device coupled to receive DC from a DC power source and configured to selectively operate in an ON state and an OFF state; and   a spark-sustain capacitor coupled to the second switch device and the igniter, the spark-sustain capacitor configured to charge from a DC power source when the first and second switch devices are operating in the ON state, and at least selectively discharge across the spark gap when the first switch device is operating in the OFF state.   
     
     
         2 . The system of  claim 1 , further comprising:
 a controller coupled to the first and second switch devices and configured to command the first and second switch devices to selectively operate in the ON states and the OFF states.   
     
     
         3 . The system of  claim 1 , further comprising:
 a first diode connected between the secondary winding and the igniter and having a first anode and a first cathode, the first anode connected to the secondary winding, the first cathode connected to the igniter; and   a second diode connected between the spark-sustain capacitor and the igniter and having a second anode and a second cathode, the second anode connected to the spark-sustain capacitor, the second cathode connected to the igniter and the first cathode.   
     
     
         4 . The system of  claim 1 , further comprising:
 a first resistance circuit connected in series with the primary winding and the first switch device; and   a second resistance circuit connected between the second switch device and the second DC power source.   
     
     
         5 . The system of  claim 1 , wherein the first and second switch devices each comprise a controllable solid-state switch. 
     
     
         6 . The system of  claim 1 , further comprising:
 a first DC power source coupled to, and configured to supply DC to, the primary winding; and   a second DC power source coupled to the second switch device, and configured to selectively charge, the spark-sustain capacitor.   
     
     
         7 . The system of  claim 6 , wherein a single power supply is configured to implement the first DC power source and the second DC power source. 
     
     
         8 . The system of  claim 6 , wherein:
 the first DC power source comprises a DC voltage source; and   the second DC power source comprises a constant current source.