Patent Application
20130047577
The following relates to and ignition exciter system, and more particularly to an ignition exciter circuit for an engine.
Ignition exciter circuits are used to provide a spark in a combustion engine. However, typical ignition exciter systems are subject to energy loss due to one or more of charge capacitor equivalent series resistance (ESR), bleeder resistors, discharge switch leakage, diode leakage current, spark gap leakage and loss due to sensing resistors. Accordingly, improved ignition exciter circuits with reduced energy loss are desirable. Other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.
In accordance with one embodiment, an ignition circuit is provided. The ignition circuit may include, but is not limited to a dc-dc converter having a positive terminal and a negative terminal and configured to be coupled to an input voltage source and electronically controlled to output an amplified voltage across the positive terminal and the negative terminal, an igniter plug having a first terminal and a second terminal, a first capacitor coupled to the positive terminal of the dc-dc converter, a first diode coupled between the first capacitor and the negative terminal of the dc-dc converter, a switching circuit electrically coupled between the positive terminal of the dc-dc converter and the negative terminal of the dc-dc converter, a transformer having a primary and a secondary winding, the primary winding coupled between the negative terminal and the second capacitor and the secondary winding coupled between the negative terminal and the first terminal of igniter plug, a second diode electrically coupled between the first capacitor and the second terminal of the igniter plug, and a second capacitor electrically coupled between the primary winding of the transformer and the second diode, wherein the first terminal of the igniter plug is electrically coupled to the secondary winding of the transformer and second terminal of the igniter plug is connected to a ground.
In accordance with another embodiment, an ignition system exciter circuit is provided. The ignition system exciter circuit may include, but is not limited to, a storage capacitor configured to receive a charge, a discharge circuit electrically connected to the storage capacitor, an igniter plug electrically connected to the discharge circuit, and a switching circuit for controlling a discharge of the storage capacitor through the discharge circuit and igniter plug. The discharge circuit may include, but is not limited to, a saturable core step-up transformer having a primary winding and a secondary winding wherein said secondary winding includes a first terminal connected to a first terminal of the primary winding and a second terminal of the secondary winding is connected to the igniter plug, and the first terminal of the primary winding receives energy from the capacitor by operation of the switching circuit, and a resonance capacitor electrically connected to a second terminal of the said primary winding,
In accordance with yet another embodiment, an engine ignition system is provided. The engine ignition system may include, but is not limited to, an amplifier configured to receive an input voltage and to selectively output an amplified voltage, a storage capacitor electrically coupled to the amplifier, a discharge circuit selectively coupled to the storage capacitor, and an igniter plug coupled to the discharge circuit. The discharge circuit may include, but is not limited to, a transformer having a primary winding and a secondary winding, and a resonant capacitor coupled to the primary winding.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Exemplary embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements; and
According to various exemplary embodiments, an ignition exciter circuit and system are provided. The ignition exciter circuit may be used in any engine. In some embodiments, for example, the ignition exciter circuit may be used in a gas turbine engine for an aircraft or as part of an automobile ignition system.
The ignition exciter circuit 100 further includes a switching circuit 120. In one embodiment, for example, switching circuit 120 may be one or more switches connected in series, parallel, or any combination thereof. In one embodiment, for example, the switching circuit 120 may be an insulated gate bipolar transistor (IGBT) 122 (hereinafter referred to as transistor 122). In other embodiment, the switching circuit 120 may be a commercial switch, such as a discharge switches or an integrated discharge switches used for pulse power applications. Typical ignition exciter circuits often utilize thyristors. However, thyristors require a complicated gate driving circuit. In contrast, a gate drive circuit required to drive the transistor 122 used in the exemplary embodiment is simpler.
A collector of the transistor 122 is electrically connected to a positive terminal output of the DC-DC converter 110, while an emitter of the transistor 122 is connected to a negative terminal output of the DC-DC converter 110. The base of the transistor 122 is electrically connected to a controller 130. In one embodiment, for example, the controller 130 may be a processor, any discrete logic, or any combination thereof. For example, the processor may be a central processing unit (CPU), a graphical processing unit (GPU), an application specific integrated device (ASIC), a field programmable gate array (FPGA), a microprocessor, or combination thereof. The controller 130 controls the transistor 122 and the DC-DC converter 110, as discussed in further detail below. In another embodiment, for example, multiple controllers may be used. For example, the ignition exciter circuit 100 may have separate controllers for the DC-DC converter 110 and the transistor 122.
In one embodiment, for example, the controller 130 may receive a command from a DEEC (Digital Electronic Engine Controller) or FADEC (Full Authority Digital Electronic Control). In response to the command, the controller 130 sends out pulses to the DC-DC converter 110 and transistor 122 to initiate a charging or discharging cycle, as discussed in further detail below.
The positive output terminal of the DC-DC converter 110 is electrically connected to a capacitor 140. The capacitor 140, which may also be referred to as storage capacitor 140, stores a charge from the DC-DC converter 110 during a charging phase, as discussed in further detail below. The size of the storage capacitor 140 may vary depending upon the spark energy requirements of the engine. In some embodiments, for example, the spark energy requirement may range from 10 milli-Joules to one Joule. However, the size of the capacitor 140 may be reduced relative to the capacitors used in prior igniter systems because the placement of diodes 150 and 160 reduce the energy lost during the charging cycle.
The diode 150 is connected between the capacitor 140 and the negative output terminal of the DC-DC converter 110. The diode 150 is oriented such that current is allowed to flow from the positive output terminal of the DC-DC converter 110 through the capacitor 140 to the negative terminal of the DC-DC converter 110, while blocking current flowing in the opposite direction.
The ignition exciter circuit 100 further includes a diode 160. In one embodiment, for example, the diode may be electrically connected between the capacitor 140 and a ground as illustrated in
The transformer 170 may be, for example, a saturable core step-up transformer which includes a primary winding 172 and a secondary winding 174. The primary winding 172 is connected in series with a capacitor 180. The capacitor 180 and the primary winding 172 of the transformer 170 form a inductor-capacitor (LC) resonant circuit and may be referred to as a discharge circuit, as discussed in further detail below. An igniter plug 190 is connected between the capacitor 180 and the secondary winding 174 of the transformer 170.
The igniter plug 190 provides a spark to an engine when a voltage across the igniter plug 190 is greater than a predetermined threshold.
After the storage capacitor 140 has been charged, the controller 130 disables the DC-DC converter 110 and closes the transistor 122. (Step 320). The capacitor 140 then begins to discharge.
The resonance voltage in primary winding 172 of the transformer 170 gets reflected onto the secondary winding 174 of the transformer 170 and is amplified based upon the turns-ratio of the transformer 170. The voltage applied at the positive terminal of the igniter plug is the sum of voltage across the storage capacitor 140 and the voltage across the secondary winding 174 of the transformer 170. The voltage at the igniter plug ionizes the air at the spark gap of the igniter plug. The inductance of the secondary winding 174 of the transformer 170 limits the rate of rise of current into the igniter plug in the beginning of discharge cycle.
Generally speaking, the various functions and features of method 300 may be carried out with any sort of hardware, software and/or firmware logic that is stored and/or executed on any platform. Some or all of method 300 may be carried out, for example, by the controller 130 illustrated in
The term “exemplary” is used herein to represent one example, instance or illustration that may have any number of alternates. Any implementation described herein as “exemplary” should not necessarily be construed as preferred or advantageous over other implementations.
Although several exemplary embodiments have been presented in the foregoing description, it should be appreciated that a vast number of alternate but equivalent variations exist, and the examples presented herein are not intended to limit the scope, applicability, or configuration of the invention in any way. To the contrary, various changes may be made in the function and arrangement of the various features described herein without departing from the scope of the claims and their legal equivalents.
