U.S. patent application number 15/045322 was filed with the patent office on 2016-06-09 for inductive start and capacitive sustain ignition exciter system.
This patent application is currently assigned to HONEYWELL INTERNATIONAL INC.. The applicant listed for this patent is HONEYWELL INTERNATIONAL INC.. Invention is credited to Deepak Pitambar Mahajan, Renukaprasad N, Srikant Varma Poosapati, Milan Rajne, Sunit Kumar Saxena.
Application Number | 20160161120 15/045322 |
Document ID | / |
Family ID | 49581115 |
Filed Date | 2016-06-09 |
United States Patent
Application |
20160161120 |
Kind Code |
A1 |
Saxena; Sunit Kumar ; et
al. |
June 9, 2016 |
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.
Inventors: |
Saxena; Sunit Kumar;
(Bangalore, IN) ; Mahajan; Deepak Pitambar;
(Bangalore, IN) ; N; Renukaprasad; (Bangalore,
IN) ; Poosapati; Srikant Varma; (Bangalore, IN)
; Rajne; Milan; (Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONEYWELL INTERNATIONAL INC. |
Morris Plains |
NJ |
US |
|
|
Assignee: |
HONEYWELL INTERNATIONAL
INC.
Morris Plains
NJ
|
Family ID: |
49581115 |
Appl. No.: |
15/045322 |
Filed: |
February 17, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13475321 |
May 18, 2012 |
|
|
|
15045322 |
|
|
|
|
Current U.S.
Class: |
361/257 |
Current CPC
Class: |
F23Q 3/006 20130101;
F23Q 3/00 20130101 |
International
Class: |
F23Q 3/00 20060101
F23Q003/00 |
Claims
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.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of application Ser. No.
13/475,321, filed May 18, 2012.
TECHNICAL FIELD
[0002] The present invention generally relates to ignition exciter
systems, and more particularly relates to an ignition exciter
system that includes inductive start and capacitive sustain
circuits.
BACKGROUND
[0003] A typical gas turbine engine includes at least a compressor
section, a combustion system, and a turbine section. During
operation, the compressor section draws in ambient air, compresses
it, and supplies the compressed air to the combustion system. A
typical combustion system includes at least a combustor, a fuel
supply line, and one or more igniters. During operation, the
combustion system receives fuel from a fuel source, via the fuel
supply line, and the compressed air from the compressor section.
The igniter(s) combusts the fuel-air mixture and supplies high
energy combusted gas to the turbine section, causing it to
rotate.
[0004] A combustion system igniter typically receives electrical
energy from an ignition exciter system. More specifically, the
ignition exciter system, in response to an ignition command
supplied from an external source, such as an engine controller,
supplies electrical energy to the igniter. The electrical energy
supplied to the igniter is sufficient to generate a spark, which
ignites the fuel-air mixture, and generates high-energy combusted
gas.
[0005] Presently known ignition exciter systems are generally based
on capacitive discharge ignition. In such topologies, a plurality
of controlled switches, which may be connected in series or
parallel, are connected in series with the energy discharge path of
the spark current. These controlled switches contribute to energy
loss. Thus, many of the presently known ignition exciter systems
have a plurality of identical voltage balancing circuits across
each of the controlled switches. Moreover, due to the poor
efficiencies, many of the presently known ignition exciter systems
include a relatively large storage capacitor to account for the
excessive energy loss in the plurality of controlled switches. The
relatively high (e.g., hundreds of amperes) discharge current that
flows through the igniter may also stress the components in the
discharge circuit path.
[0006] Thus, while presently known ignition exciter systems are
generally safe, reliable, and robust, these systems can exhibit
certain drawbacks. For example, the printed circuit board area
occupied by relatively large storage capacitors and/or other
components can result in relatively large enclosures, which in turn
may lead to more space being occupied on the engine, can increase
weight, and may result in a less efficient system.
[0007] Hence, there is a need for an ignition exciter system that
uses relatively less components and/or occupies less space and/or
weighs less than existing systems and/or is not relatively less
efficient that existing systems. The present invention addresses
one or more of these needs.
BRIEF SUMMARY
[0008] In one embodiment, 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 and a secondary winding. The primary winding is adapted to
selectively receive direct current (DC) from a DC source, and the
secondary winding 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.
[0009] In another embodiment, an ignition exciter system includes
an igniter, a step-up transformer, a first switch device, a second
switch device, and a spark-sustain capacitor.
[0010] The step-up transformer has a primary winding and a
secondary winding. The primary winding is coupled to receive direct
current (DC) from a DC power source, and the secondary winding is
coupled to the igniter. The step-up transformer is configured to at
least selectively generate a voltage at the secondary winding that
is sufficient to generate a spark across the spark gap. The first
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 second switch device is coupled to
receive DC from a DC power source and is configured to selectively
operate in an ON state and an OFF state. The spark-sustain
capacitor is coupled to the second switch device and the igniter.
The spark-sustain capacitor is 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.
[0011] Furthermore, other desirable features and characteristics of
the ignition exciter system will become apparent from the
subsequent detailed description and the appended claims, taken in
conjunction with the accompanying drawings and the preceding
background.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The present invention will hereinafter be described in
conjunction with the following drawing figures, wherein like
numerals denote like elements, and wherein:
[0013] FIG. 1 depicts a functional block diagram of an embodiment
of an ignition exciter system; and
[0014] FIG. 2 depicts a schematic diagram of one embodiment of a
circuit that may be used to implement a portion of the ignition
exciter system depicted in FIG. 1;
[0015] FIGS. 3-5, respectively, depict exemplary waveforms of
voltage, current, and power delivered by the circuit of FIG. 2 to
an igniter;
[0016] FIG. 6 depicts an exemplary waveform of current through the
transformer secondary of the circuit depicted in FIG. 2;
[0017] FIG. 7 depicts a schematic diagram of another embodiment of
a circuit that may be used to implement a portion of the ignition
exciter system depicted in FIG. 1; and
[0018] FIG. 8 depicts a schematic diagram of yet another embodiment
of a circuit that may be used to implement a portion of the
ignition exciter system depicted in FIG. 1
DETAILED DESCRIPTION
[0019] The following detailed description is merely exemplary in
nature and is not intended to limit the invention or the
application and uses of the invention. As used herein, the word
"exemplary" means "serving as an example, instance, or
illustration." Thus, any embodiment described herein as "exemplary"
is not necessarily to be construed as preferred or advantageous
over other embodiments. All of the embodiments described herein are
exemplary embodiments provided to enable persons skilled in the art
to make or use the invention and not to limit the scope of the
invention which is defined by the claims. Furthermore, there is no
intention to be bound by any expressed or implied theory presented
in the preceding technical field, background, brief summary, or the
following detailed description.
[0020] Referring now to FIG. 1, a functional block diagram of an
embodiment of an ignition exciter system 100 is depicted and
includes an igniter 102, a spark generation circuit 104, a spark
sustain circuit 106, a controller 108, and an input power
processing circuit 110. The igniter 102 may be any one of numerous
known igniters 102 that include a spark gap 112, and that is
configured, upon receipt of a sufficiently high voltage, to
generate a spark across the spark gap 112. Although only a single
igniter 102 is depicted, it will be appreciated that more than one
igniter could be included.
[0021] The spark generation circuit 104 is coupled to the igniter
102 and is further coupled to receive commands from the controller
108. The spark generation circuit 104 is configured, in response to
the commands supplied from the controller 108, to selectively
generate a voltage that is sufficient to generate a spark across
the spark gap 112. As will be described in more detail further
below, the spark generation circuit 104 is implemented as an
inductive circuit.
[0022] The spark sustain circuit 106 is coupled to the spark
generation circuit 104 and is also coupled to the igniter 102. The
spark sustain circuit 106 is configured to selectively supply a
current to the igniter 102. More specifically, and as will be
described in more detail further below, after the spark generation
circuit 104 causes the igniter to generate a spark across the spark
gap 112, the spark sustain circuit 106 supplies current to the
igniter 102 to sustain the spark for a required time duration.
[0023] The controller 108, as noted above, is configured to supply
commands to the spark generation circuit 104. The controller 108
supplies the commands to the spark generation circuit 104 to
control the spark rate of the igniter 102. Though not depicted, the
controller 108 may generate the commands in response to signals
received from an external device, such as a non-illustrated engine
controller, or the controller 108 may be implemented as part of the
engine controller itself.
[0024] The input power processing circuit 110 is adapted to receive
electrical power and is configured to supply DC power to the spark
generation circuit 104 and the spark sustain circuit 106. The
electrical power to the input power processing circuit 110 may be
supplied from any one of numerous AC or DC sources. Regardless of
the source of electrical power, the input power processing circuit
110 is configured to provide line, load, and temperature regulated
stable DC voltages to the spark generation and spark sustain
circuits 104, 106. The input power processing circuit 110 may be
implemented using any known configuration of rectifiers, inverters,
switched mode power supplies, batteries, passive electrical
elements, electromagnetic devices, or machines, just to name a
few.
[0025] A schematic diagram that depicts embodiments of the spark
generation circuit 104 and the spark sustain circuit 106 is
provided in FIG. 2, and will be described in detail. Before doing
so, however, it is noted that the ignition exciter system 100,
though not depicted in FIG. 1, may be implemented with additional
functional circuit blocks. For example, the ignition exciter system
100 may include a built-in-test (BIT) circuit, one or more control
power supplies, an input power processing circuit, and an input
power supply, just to name a few.
[0026] Turning now to FIG. 2, the spark generation circuit 104 will
first be described. This circuit includes a step-up transformer 202
and a switch device 204. The step-up transformer 202 includes a
primary winding 206 and a secondary winding 208, and is configured
to at least selectively generate a voltage at the secondary winding
208 that is sufficient to generate a spark across the spark gap
112. It will be appreciated that the magnitude of the voltage that
is generated at the secondary winding 208 will depend upon the
ratio of the number of turns in the primary winding 206 to the
number of turns in the secondary winding 208, and upon the voltage
magnitude connected to the primary winding 206. It will
additionally be appreciated that the voltage generated at the
secondary winding 208 may vary based upon, for example, the voltage
needed to generate the spark.
[0027] To implement the above-described functionality, the primary
winding 206 is connected, via a first resistance circuit 212, to a
first DC voltage source 214, and the secondary winding 208 is
connected in series with the igniter 102 and a first diode 216. The
first resistance circuit 212 may be implemented using a single or
multiple resistors, or using any one or more circuit elements that
exhibit a desired amount of electrical resistance. The first DC
voltage source 214 may be implemented using any one of numerous DC
voltage generation circuits. For example, it may be implemented
using any one of numerous AC/DC converters, any one of numerous
DC/DC converters, or a simple battery. The first diode 216 may be
implemented using a conventional diode or any one of numerous other
unidirectional elements or circuits. In the depicted embodiment,
however, the first diode 216 is conventional diode that includes a
first anode 215 and a first cathode 217. The first anode 215 is
connected to the secondary winding 208, and the first cathode 217
is connected to the igniter 102.
[0028] The switch device 204 is coupled to the primary winding 206
and is configured to selectively operate in an ON state and an OFF
state. More specifically, the switch device 204 is responsive to
the commands supplied from the controller 108 to operate in an ON
state or an OFF state. When the switch device 204 is in the ON
state, current may flow from the first DC voltage source 214
through the primary winding 206. Conversely, when the switch device
204 is in the OFF state, current will not flow through the primary
winding 206. The switch device 204 may be implemented using any one
of numerous types of controllable switches or switching devices. In
a preferred embodiment, the switch device 204 is implemented using
a solid-state device, such as a silicon-controlled rectifier (SCR),
an insulated gate bipolar transistor (IGBT), a gate turn-off (GTO)
thyristor, a metal-oxide semiconductor field-effect transistor
(MOSFET), or an integrated gate-commutated thyristor (IGCT), just
to name a few.
[0029] As FIG. 2 further depicts, the spark generation circuit 104
may optionally include a switch-protection diode 218, and an
over-voltage clamp circuit 222. The switch-protection circuit 218,
if included, is connected across the switch device 204. The
over-voltage clamp circuit 222, if included, is connected in
parallel with the primary winding 206 and includes a clamp
capacitor 224, a clamp diode 226 connected in series with the clamp
capacitor, and a clamp resistance circuit 228 connected in parallel
with the clamp capacitor 224. The depicted over-voltage clamp
circuit 222 is a passive circuit, and protects the switch device
204 in the unlikely event of an open circuit condition at the
secondary winding 208. It will be appreciated that the depicted
over-voltage clamp circuit 222 is merely exemplary of one type of
circuit that can be used to implement this functionality, and that
other circuits, both passive and active, could be used.
[0030] Turning now to the spark sustain circuit 106, it is seen
that this circuit includes at least a spark-sustain capacitor 232.
The spark-sustain capacitor 232 is configured to charge from a
second DC voltage source 234 when the switch device 204 is
operating in the ON state, and at least selectively discharge
across the spark gap 112 when the switch device 204 is operating in
the OFF state. To do so, the spark-sustain capacitor is coupled to
the igniter 102 via a second diode 236, and is additionally coupled
to the second DC voltage source 234 via a second resistance circuit
238. It will be appreciated that the second DC voltage source 234
may be implemented wholly independent of the first DC voltage
source 214, or the first and second DC voltage sources 214, 234 may
be implemented using a single power supply 242 (as indicated in
phantom in FIG. 2). It will additionally be appreciated that spark
sustain capacitor 232 may be implemented using a single or multiple
capacitors that exhibit a desired amount of capacitance.
[0031] The third resistance circuit 238 may be implemented using a
single or multiple resistors, or using any one or more circuit
elements that exhibit a desired amount of electrical resistance.
The second DC voltage source 234 may also be implemented using any
one of numerous DC voltage generation circuits. For example, it may
be implemented using any one of numerous AC/DC converters, any one
of numerous DC/DC converters, or a simple battery. The second diode
236 may be implemented using a conventional diode or any one of
numerous other unidirectional elements or circuits. In the depicted
embodiment, however, the second diode 236 is conventional diode
that includes a second anode 235 and a second cathode 237. The
second anode 235 is connected to the spark-sustain capacitor 232,
and the second cathode 237 is connected to both the igniter 102 and
the first cathode 217.
[0032] Having described the structure and general function of the
ignition exciter system 100, the operation of the ignition exciter
system 100 will now be described. In doing so, it will be assumed
that the spark generation circuit 104 and spark sustain circuit 106
are both fully discharged and/or de-energized, and that the switch
device 204 is in the OFF state.
[0033] When the controller 108 commands the switch device to the ON
state, DC current flows through, and magnetic energy is stored in,
the primary winding 206 of the step-up transformer 202. At the same
time, the spark-sustain capacitor 232 is charged, via the second
resistance circuit 238, from the second DC voltage source 234. The
spark-sustain capacitor 232 stores its charge until the switch
device 204 is commanded to operate in the OFF state.
[0034] When the controller 108 commands the switch device 204 to
the OFF state, the magnetic energy in the primary winding 206 is
converted to a relatively large magnitude voltage pulse at the
secondary winding 208. This relatively large magnitude voltage
pulse ionizes the air in the spark gap 112, and generates a spark.
This creates a low resistance discharge path for the spark-sustain
capacitor 232, which discharges, via the second diode 236, through
the igniter 102. As may be appreciated, the controller 108 may be
configured to command the switch device 204 to switch between
operating in the ON state and OFF state at an interval to generate
sparks at a desired spark rate.
[0035] To even more clearly illustrate the operation of the
ignition exciter system 100, reference should be made to FIGS. 3-6,
which depict various waveforms of electrical parameters within the
system 100. At time (t.sub.0) the switch device 204 is in the OFF
state. Thus, as depicted in FIG. 3, this causes the stored magnetic
energy in step-up transformer 202 to appear as very high voltage
across the spark gap 112. As a result, the air in the spark gap 112
ionizes and becomes conductive and, as depicted in FIG. 4, at the
complete breakdown of the air in the spark gap 112, the
spark-sustain capacitor 232 starts discharging and supplying
current to sustain the spark. The electrical power delivered to the
spark gap 112 is depicted in FIG. 5, and the current through the
secondary winding 208 of step-up transformer 202 is depicted in
FIG. 6. As may be readily apparent from FIG. 6, the step-up
transformer 202 does not supply the current needed to sustain the
spark in the igniter plug 102; rather, it only initiates the spark.
It is the spark-sustain capacitor 232 that sustains the spark.
[0036] The spark generation circuit 104 and the spark sustain
circuit 106 depicted in in FIG. 2 are merely exemplary of one
embodiment for implementing these circuits, and various other
circuit configurations may be used. For example, in the alternative
embodiment depicted in FIG. 7, the first voltage source 214 and the
second voltage source 234 are replaced with a single voltage source
702, and the spark sustain circuit 106 includes a second switch
device 704. The voltage source 702 may be variously implemented and
may be, for example, an AC/DC converter, a DC/DC converter, or a
constant voltage power supply. The second switch 704 is connected
between the third resistance circuit 238 and a node common to the
spark-sustain capacitor 232 and the anode 235 of the second diode
236. The second switch device 704 disconnects the single voltage
source 702 from the spark sustain circuit 106 when the
spark-sustain capacitor 232 is supplying current to the spark gap
112. This further improves the efficiency of the system 100 by
eliminating current flow through the third resistance circuit 238
during the sparking event. This also eliminates the potential of
drawing energy from the single voltage source 702 when it is not
required, which may be especially useful when the system 100 is fed
from a battery.
[0037] Yet another embodiment is depicted in FIG. 8. In this
embodiment, the first voltage source 214 is replaced with a
constant voltage source 802, and the second voltage source 234 is
replaced with a constant current source 804. The constant voltage
source 802 may be variously implemented. For example, it may be
implemented as an AC/DC converter, a DC/DC converter, or a constant
voltage power supply. This embodiment also includes the second
switch device 704, but eliminates the third resistance circuit 238,
and thus its associated losses.
[0038] The ignition exciter system 100 described herein uses an
inductive circuit (the spark generation circuit 104) to generate
high voltage sufficient enough only to ionize the spark gap 112 and
initiate a spark in an igniter 102, and a relatively low voltage
capacitive circuit (the spark-sustain circuit 106) to supply the
spark energy after the spark is initiated. With the described
system, the spark current and spark voltage across the spark gap
ascend simultaneously and thus the peak current needed to meet the
peak power is significantly reduced. The described system
additionally enhances efficiency, reduces part count, and thus
reduces costs.
[0039] In this document, relational terms such as first and second,
and the like may be used solely to distinguish one entity or action
from another entity or action without necessarily requiring or
implying any actual such relationship or order between such
entities or actions. Numerical ordinals such as "first," "second,"
"third," etc. simply denote different singles of a plurality and do
not imply any order or sequence unless specifically defined by the
claim language. The sequence of the text in any of the claims does
not imply that process steps must be performed in a temporal or
logical order according to such sequence unless it is specifically
defined by the language of the claim. The process steps may be
interchanged in any order without departing from the scope of the
invention as long as such an interchange does not contradict the
claim language and is not logically nonsensical.
[0040] Furthermore, depending on the context, words such as
"connect" or "coupled to" used in describing a relationship between
different elements do not imply that a direct physical connection
must be made between these elements. For example, two elements may
be connected to each other physically, electronically, logically,
or in any other manner, through one or more additional
elements.
[0041] While at least one exemplary embodiment has been presented
in the foregoing detailed description of the invention, it should
be appreciated that a vast number of variations exist. It should
also be appreciated that the exemplary embodiment or exemplary
embodiments are only examples, and are not intended to limit the
scope, applicability, or configuration of the invention in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing an
exemplary embodiment of the invention. It being understood that
various changes may be made in the function and arrangement of
elements described in an exemplary embodiment without departing
from the scope of the invention as set forth in the appended
claims.
* * * * *