BACKGROUND OF THE INVENTION
Turbine engines, and particularly gas turbine engines, also known as combustion f
turbine engines, are rotary engines that extract energy from a flow of combusted gases
passing through the engine onto a multitude of turbine blades. Gas turbine engines have
been used for land and nautical locomotion and power generation, but are most
commonly used for aeronautical applications such as for airplanes, including helicopters. {
In airplanes, gas turbine engines are used for propulsion of the aircraft. f.
Gas turbine engines can have two or more spools, including a low pressure (LP)
spool that provides a significant fraction of the overall propulsion system thrust, and a high
" * pressure (HP) spool that drives one or more compressors and produces additional thrust by I
directing exhaust products in an aft direction. A triple spool gas turbine engine includes a
third, intermediate pressure (IP) spool.
Gas turbine engines also usually power a number of different accessories such as j
generators, starter/generators, permanent magnet alternators (PMA), fuel pumps, and f
hydraulic pumps, e.g., equipment for functions needed on an aircraft other than I
propulsion. For example, contemporary aircraft need electrical power for avionics,
motors, and other electric equipment. A generator coupled with a gas turbine engine
will convert the mechanical power of the engine into electrical energy needed to power
accessories. i
Autotransformers (ATUs) are frequently used in power applications to i
^ p interconnect systems operating at different voltage classes and to reduce the harmonic
contents of the generators and the ripples at the outputs of the rectifiers. In aircrafts,
autotransformers typically are used to step up or down voltages between generators and
rectifiers. ATUs are separate from the generator, and add to the weight and volume of
the engine. Furthermore, ATUs often require a forced liquid cooling system, which adds
additional weight and volume to the engine.
BRIEF DESCRIPTION OF THE INVENTION
In one embodiment, a power generation system for a gas turbine engine having a
pressure spool includes an AC generator with an integrated auto transformer unit having
at least two three-phase outputs from the integrated auto transformer unit, a rectifier I.
2 |
|
matrix connected to the at least two three-phase output, and a filter connected to the rectifier matrix configured to provide DC output to a bus.
In another embodiment, an electrical architecture for a gas turbine engine having a high pressure (HP) spool and a low pressure (LP) spool includes a first AC generator j
coupled to the LP spool and comprising a first integrated auto transformer unit having at least two three-phase outputs from the first integrated auto transformer unit, a second
AC generator coupled to the HP spool and comprising a second integrated auto j
transformer unit having at least two three-phase outputs from the second integrated auto j
transformer unit, a first AC/DC converter connected to the at least two three-phase outputs of the first AC generator, and to a first DC bus, and a second AC/DC converter j
^ ^ connected to the at least two three-phase outputs of the second AC generator, and to a
second DC bus, wherein the first and second DC buses are selectively connected. j
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings: |
FIG 1 is a schematic cross-sectional diagram of a gas turbine engine for an j
aircraft; i
j
FIG 2 is a schematic block diagram of an electrical power system architecture
for the gas turbine engine of FIG. 1, the system architecture having a generator with an
integrated autotransformer unit in accordance with a first embodiment of the invention;
FIG. 3 is an electrical diagram of the generator with the integrated
autotransformer unit and an AC-to-DC power converter of the electrical power system
^ p architecture of FIG 2.
FIG 4 is an electrical diagram of a stator winding for the generator with the
integrated autotransfbrmer unit from FIG. 3;
FIG 5 is a winding vector diagram for the stator winding from FIG 4; I
FIG 6 is a schematic block diagram of an electrical power system architecture
for the gas turbine engine of FIG 1, the system architecture having an integrated
autotransformer unit in accordance with a second embodiment of the invention; FIG. 7 is an electrical diagram of the generator with the integrated autotransformer unit and an AC-to-DC power converter of the electrical power system
architecture of FIG 6.
3 I
|
FIG 8 is an electrical diagram of a stator winding for the generator with the
integrated autotransformer unit from FIG. 3;
FIG 9 is a winding vector diagram for the stator winding from FIG. 8; FIG 10 is a schematic block diagram of an electrical power system architecture [
for the gas turbine engine of FIG 1, the system architecture having a generator with an integrated autotransformer unit in accordance with a third embodiment of the invention; {
FIG 11 is an electrical diagram of the generator with the integrated }
autotransformer unit and an AC-to-DC power converter of the electrical power system j
architecture of FIG. 10. |
DESCRIPTION OF EMBODIMENTS OF THE INVENTION j
" " ' The described embodiments of the present invention are directed to power j
extraction from an aircraft engine, and more particularly to an electrical power system <
architecture which enables production of electrical power from a turbine engine,
preferably a gas turbine engine. It will be understood, however, that the invention is not so limited and has general application to electrical power system architectures in non- j
aircraft applications, such as other mobile applications and non-mobile industrial, I
commercial, and residential applications. j
FIG 1 is a schematic cross-sectional diagram of a gas turbine engine 10 for an f
aircraft. Engine 10 includes, in downstream serial flow relationship, a fan section 12
including a fan 14, a booster or low pressure (LP) compressor 16, a high pressure (HP) I
compressor 18, a combustion section 20, a HP turbine 22, and a LP turbine 24. A HP f
i ^ shaft or spool 26 drivingly connects HP turbine 22 to HP compressor 18 and a LP shaft
or spool 28 drivingly connects LP turbine 24 to LP compressor 16 and fan 14. HP
turbine 22 includes an HP turbine rotor 30 having turbine blades 32 mounted at a
periphery of rotor 30. Blades 32 extend radially outwardly from blade platforms 34 to !
radially outer blade tips 36.
FIG 2 is a schematic block diagram of an electrical power system architecture
40 according to a first embodiment of the invention. The system architecture 40 includes
multiple engine systems, shown herein as including at least a left engine system 42 and a
right engine system 44. The left and right engine systems 42, 44 may be substantially
identical; therefore, only the left engine system 42 will be described in detail for the sake
4
I
of brevity. The left engine system 42 can include the HP and LP spools 26, 28 of the
gas turbine engine 10 shown in FIG. 1, although the system architecture 40 has
|
application to other engines as well. The left engine system 42 shown herein uses |
s
mechanical power provided by two spools, the HP spool 26 and the LP spool 28.
However, the system architecture 40 could also be implemented on an engine having j
more than two spools, such as a 3-spool engine having an intermediate pressure spool in I
I
addition to the HP and LP spools. The system architecture 40 can further include an j
I
auxiliary power unit (APU) 46 of the aircraft and an external power source (EPS) 48. j
As shown herein, the APU 46 and EPS 48 each have a DC output 50, 52, respectively. j
In the embodiment illustrated, the left engine system 42 includes a first 1
i i
* ^ autotransformer unit (ATU) integrated generator 56, shown herein as an ATU integrated j
starter-generator 56, configured to produce variable frequency (VF) AC power from [
mechanical power supplied by the HP spool 26, and a second ATU integrated generator {
58 configured to produce constant frequency (CF) AC power from mechanical power I
I
supplied by the LP spool 28. I
i
The ATU integrated starter-generator 56 includes a power generation section 60 f
f
and an ATU section 62. As will be explained in greater detail below, the ATU section !
62 is integrated with the power generation section 60 by integrating some of the electrical windings necessary for power transformation on the electrical winding of the
power generation section 60. This essentially eliminates winding duplication in the
I
power generation section 60 and the ATU section 62, which can translate into weight f
i # and cost savings for the aircraft. f
The HP spool 26 can be operably coupled with the ATU integrated startergenerator
56 by an HP drive assembly having an input mechanically coupled to the HP spool 26 and an output mechanically coupled to the power generation section 62. One X
embodiment of the HP drive assembly is an accessory gearbox 64, where the ATU
integrated starter-generator 56 can be mounted and coupled to the accessory gearbox 64.
Within the accessory gearbox 64, power may also be transferred to other engine
accessories. The power generation section 60 of the ATU integrated starter-generator 56
converts mechanical power supplied by the HP spool 26 into electrical power and
produces a power supply 66 having three phase outputs. The ATU section 62 of the
ATU integrated starter-generator 56 functions to both transform the three phase outputs
5 i
of the power supply 66 into a nine phase power output 68 and to step up the voltage of I
the power supply.
The ATU integrated starter-generator 56 also provides a starting function to the j
aircraft. Alternatively, the ATU integrated generator 56 on the HP side of the left engine
system 42 may comprise a generator that does not provide a starting function to the
aircraft. In this case, a separate starter motor connected to the accessory gearbox 60 can I
be provided to perform the starting function for the aircraft. Furthermore, the left engine j
system 42 can include multiple generators drawing mechanical power from the HP spool 26 to produce power in order to provide a measure of redundancy.
The ATU integrated generator 58 includes a power generation section 70 and an
g ^ ATU section 72. The LP spool 28 can be operably coupled with the ATU integrated [
generator 58 by an LP drive assembly having an input mechanically coupled to the LP I
spool 28 and an output mechanically coupled to the power generation section 70. One
embodiment of the LP drive assembly is a constant speed drive (CSD) 74 which
converts the variable speed input from the LP spool 28 to constant speed. As shown I
herein, the CSD 74 can be mechanically coupled to the ATU integrated generator 58 and
drives the power generation section 70 at a constant speed. The power generation section 70 of the ATU integrated generator 58 converts mechanical power supplied by
the LP spool 28 into electrical power and produces a power supply 76 having three
phase outputs. The ATU section 72 of the ATU integrated generator 58 functions to
both transform the three phase outputs of the power supply 76 into a nine phase power j
^ output 78 and to step up the voltage of the power supply. Due to the CSD, the power
^* supplies 66, 76 will have constant frequency. Alternatively, the CSD 74 can be
eliminated to produce a VF power output.
Although the embodiment shown herein is described as using one ATU
integrated generator 58 on the LP side of the left engine system 42, another embodiment
of the invention may use multiple ATU integrated generators 58 drawing mechanical
power from the LP spool 28 to produce AC power in order to provide a measure of
redundancy. Furthermore, while a separate ATU integrated generator 58 and CSD 74
are discussed herein, an integrated drive generator which combines the CSD 74 and
ATU integrated generator 58 into a common unit can alternatively be used.
6 !
i
The power output 68 from the an integrated ATU integrated starter-generator 56
is supplied to first AC/DC converter for converting the AC power output 68 to a DC
power output 80. As illustrated, the first AC/DC converter can include a first rectifier
device 82 and a first filter 84 for converting the AC voltage to DC voltage and for
evening out the current flow before being supplied to a first electrical bus 86. Similarly, !
the power output 78 from the ATU integrated generator 58 is supplied to second AC/DC [
converter for converting the AC power output 78 to a DC power output 88. As j
illustrated, the second AC/DC converter can include a second rectifier device 90 and a j
second filter 92 for converting the AC voltage to DC voltage and for evening out the current flow before being supplied to a second electrical bus 94. !
£S A motor-starter controller 96 can selectively provide power from the first j
electrical bus 86 to the ATU integrated starter-generator 56 to initiate a starting 1
f
procedure for the aircraft. The motor-starter controller 96 can be integrated with the
ATU integrated starter-generator 56 for engine starting by connecting the motor-starter controller 96 to the specific location of the ATU integrated starter-generator 56 as shown FIG 2. The three phase motor-starter controller 96 is connected to the three S
phase power supply 66 to drive the ATU integrated starter-generator 56 as a three phase f
starter for engine starting.
The first and second electrical buses 86, 94 are configured to supply DC power
to one or more loads (not shown) that require a DC power supply. The first and second electrical buses 86, 94 can be selectively connected to enable loads to be shared by the f
HP spool 26 and the LP spool 28. [
™ In operation, with the gas turbine engine 10 stared, HPT 22 rotates the HP spool
26 and the LPT 24 rotates the LP spool. The accessory gearbox 64 is driven by the
rotating HP spool 26, and transmits mechanical power from the HP spool 26 to the ATU f
integrated starter-generator 56. The ATU integrated starter-generator 56 converts J
mechanical power supplied by the HP spool 26 into electrical power and produces the
DC power output 80. The CSD 74 is driven by the rotating LP spool 28, and transmits
mechanical power from the LP spool 28 to the ATU integrated generator 58. The ATU
integrated generator 58 converts the mechanical power supplied by the LP spool 28 into
electrical power and produces the DC power output 88. The power outputs 80, 88 can be respectively provided to the electrical buses 86, 94 configured to supply DC power to 1 I
one or more loads (not shown) that require a DC power supply. Depending on the type
of load drawing power, the DC power extracted by the system architecture 40 may
undergo further processing before being used by the loads. The DC power outputs 50,
52 of the APU 44 and the EPS 48 can also be provided to the electrical buses 86, 94.
The left and right engine systems 42, 44, APU 46 and EPS 48 can provide DC
power to various loads of the aircraft as needed. The various DC outputs of the left j
engine system 42, the right engine system 44, the APU 46, and the EPS 48 are integrated with appropriate switches to provide no break power transfer (NBPT) to the aircraft. j
FIG 3 is an electrical diagram of the ATU integrated starter-generator 56 and the
first AC-to-DC power converter for use in the electrical power system architecture 40 of
gs Fig. 2. The first and second ATU integrated generators 56, 58 and AC-to-DC power
converters may be substantially identical for both the HP spool 26 and the LP spool 28;
therefore, only the HP side of the left engine system 42 will be described in detail in
FIG 3 for the sake of brevity.
The ATU integrated starter-generator 56 can have a stator with three main or
primary windings 98a to 98c and nine secondary windings 100a to lOOi. The main
windings 98a to 98c each have a neutral end connected to a common neutral point 102
and a tap 104a to 104c connected to one phase output 106a to 106c of the three phase
output power supply 66. The phase outputs 106a to 106c are provided via conductors or
lead wires to the three-phase motor-starter controller 96 (FIG 2). The secondary
windings 100a to lOOi are connected in associated trios to one of the taps 104a to 104c
on the main windings 98a to 98c, and are configured to generate the nine phase power
^ ^ output 68. In the illustrated embodiment, the primary windings 98a to 98c are arranged
in a Wye configuration, with the overall configuration of integrated ATU being a star
connected configuration. Alternatively, the primary windings 98a to 98c can be
arranged in a Delta configuration, with the overall configuration of integrated ATU
being a Delta or Extended Delta connected configuration.
The nine phase power output 68 is delivered by conductors 108a to 108i to the
rectifier device 82. The conductors 108a to 108i can be lead wires. The rectifier device I
82 can be integrated and packaged with the generator 56, or provided separately from
the generator 56. The rectifier device 82 can include three rectifier bridges containing
multiple diodes. The number of diodes is equal to the desired pulse count of the ATU i
8 !
f
I
integrated starter-generator 56. As shown herein, there are eighteen diodes, and so the j
pulse count is eighteen. Other numbers of diodes, such as 12,18, 24, other multiples of j
six, etc. can also be used. One suitable type of diode is made from silicon carbide (SiC) l
II
due to its high temperature capability. Rectifying devices other than diodes can be used. I
Although the illustrated integrated starter-generator 56 is shown as having a I
pulse count of eighteen, as mentioned above, the starter-generator 56 can be configured {
to have other pulse counts. For example, by providing two secondary windings 100
instead of three, a generator with a pulse count of twelve can be provided. In another
t
example, by providing four secondary windings 100 instead of three, a generator with a f
pulse count of twenty-four can be provided. I
C As illustrated, the conductors 108a, 108e, and 108i are connected to a first i
j
rectifier bridge 110 having six diodes 112, the conductors 108c, 108d, and 108h are
connected to a second rectifier bridge 114 having six diodes 116, and the conductors
108b, 108f, and 108g are connected to a third rectifier bridge 118 having six diodes 120. I
The three phases available on the conductors 108a, 108e, and 108i are rectified by the first rectifier bridge 110, with the diodes 112 delivering a first DC voltage
between two first outputs 122a and 122b. The three phases available on the conductors
108c, 108d, and 108h are rectified in parallel by the second rectifier bridge 114, with the
diodes 116 delivering a second DC voltage between two second outputs 124a and 124b.
The three phases available on the conductors 108b, 108f, and 108g are also rectified in
parallel by the third rectifier bridge 118, with the diodes 120 delivering a second DC
voltage between two third outputs 126a and 126b.
^ One output 122a, 124a, and 126a from each rectifier bridge 110, 114, 118 is
coupled to a first interphase transformer 128 which absorbs the instantaneous voltage |
differences between the outputs 122a, 124a, and 126a. The other output 122b, 124b, and
126b from each rectifier bridge 110, 114, 118 is coupled to a second interphase
transformer 130 which absorbs the instantaneous voltage differences between the j
outputs 122b, 124b, and 126b. The junction points between the coils of the first and second interphase transformers 128, 130 form first and second outputs 132, 134, I
respectively, which are connected to the filter 84. !
FIG. 4 is an electrical diagram of the stator winding for the ATU section 62 of j
the ATU integrated starter-generator 56 from FIG. 3. As discussed above, each main <
9 I
j
f
f
I
winding 98a to 98c extends from the common neutral point 102 to one of the taps 104a [
i
to 104c. The secondary windings 100a to 100c on the first main winding 98a extend j
j
from the tap 104a to a terminal Al, A2, A3, respectively. The secondary windings lOOd {
to 1 OOf on the second main winding 98b extend from the tap 104b to a terminal B1, B2,
B3, respectively. The secondary windings lOOg to lOOi on the third main winding 98c
extend from the tap 104c to a terminal CI, C2, C3, respectively. j
FIG. 5 is a winding vector diagram for the stator winding for the ATU section 62 |
of the ATU integrated starter-generator 56 of FIG. 4. The winding vector diagram can be used to design the stator winding for the ATU section 62 of the ATU integrated j
starter-generator 56. The stator winding is illustrated herein as having a pulse count of
W£ eighteen, although the stator winding can also be configured to have a pulse count in I
other multiple of six, such as 12, 18, 24, etc.
As can be seen, the vector diagram includes nine main vectors Al, A2, A3, Bl,
B2, B3, CI, C2, C3 emanating from a common point of origin O, which corresponds to j
the neutral point 102 of the stator winding in FIG. 4. The main vectors A1-C3 represent
the phase outputs which are delivered by conductors 108a to 108i to the rectifier device S
82 in FIG. 3. The magnitude or length V of the main vectors A1-C3 represents the f
generated AC voltage and the direction or orientation of each main vector A1-C3
represents the phase from 0-360° of the generated AC voltage. As shown herein, the
main vectors A1-C3 can have the same length V, but differ in phase by an angle a. The
main vectors A1-C3 can be grouped, such that main vectors Al, Bl, CI represent the
one three-phase output, the main vectors A2, B2, C2 represent another three-phase
^ ^ output, and the main vectors A3, B3, C3 represent the other three-phase output
Each of the main vectors Al, Bl, and CI includes two sub-vectors XI, X2, Yl,
Y2, Zl, Z2 emanating from a point P (which corresponds to the taps 104a-c in FIG. 4) to
meet one of the other main vectors A2, A3, B2, B3, C2, C3. The distance between the
common point of origin O and point P is represented as length LI. The distance from
point P to the end of main vector Al is represented as length L2. As such, the length V [
of the main vector Al, and therefore all the other main vectors A2, A3, B2, B3, C2, C3
is given by the following relationship: V = \Ll\ + \L210 !
I
1
I
I
Sub-vector X2 extends from main vector Al to main vector A3 at an angle 01
and has a length L3. While not shown in FIG. 5, the other sub-vectors X2, Yl, Y2, Zl, f
f
Z2 also have a length L3, and extend from the associated main vector at an angle equal to 01. The ends of main vectors Al and A3 are separated by a distance d, which
together with lengths L2 and L3, form a triangle having vertices defining interior angles
01, 02, and 03. The lengths L1-L3 and angles 01 and a can be selected to design the
stator winding for the ATU section 62 of the ATU integrated starter-generator 56 from
FIG. 3. i
The angles a, 01, 02, and 03 are dependent on the number of pulses N, and the relationship therebetween is given by the following equations:
C 360
t 36003 = 1180'--— | + 2
N !
82 = 180= - 01 - 83 In this example, it can be given that N=l 8 and 01 = 60°. Thus, angle a = 20°, J
angle 03 = 80° and angle 02 = 40°. It is understood that 02 or 03 could be given instead
ofGl.
The relationship between the lengths L2, L3, d and the angles 01, 02, and 03 is
known from the law of sines as:
\d\ = [L2\_ = |L31
sin 81 sin 82 sin 83
The distance d from the end of main vector A1 to the end of main vector A3 is
^ given by the following relationship:
180
\d\ = iVsin-^r-
JV 5
Using the law of sines, the lengths L2 and L3 are therefore given by the
following relationships:
|d|sing2_2l'siB—sing2 |
' 2 ' ~ sindl ~ sintfl j
1 SO '''
_ \d\sin83 _ 2F sin—sin A3 [
' 3 | ~ sin01 ~ sin01 j
Using the relationship between the voltage V and lengths LI, L2, the length LI •
can be determined using the following relationship:
11 |
i
|L1| = (V-|L2|)
Thus, by knowing the desired number of pulses N, the desired voltage V, and at least one other variable, the main stator winding for the ATU section 62 of the ATU integrated starter-generator 56 from FIG. 3 can be designed. In this case, the other
variable given is 01. However, it will be understood that another variable, such as a
different angle or a length, could be given instead.
FIG. 6 is a schematic block diagram of an electrical power system architecture j.
140 according to a second embodiment of the invention. The system architecture 140 may
be substantially similar to the system architecture 40 shown in FIG 2; therefore, like
elements will be referred to using the same reference numerals. One difference between
f*\ the system architecture 140 shown in FIG 6 and the system architecture 40 shown in
FIG. 2 is that, for both ATU integrated generators 56, 58, the ATU section 62, 72
functions to transform the three phase outputs of the power supply 66, 76 into a nine
phase power output 142, 144 by adding two secondary windings instead of adding three
windings.
FIG 7 is an electrical diagram of the ATU integrated starter-generator 56 and the
first AC-to-DC power converter for use in the electrical power system architecture 140
of Fig. 6. The first and second ATU integrated generators 56, 58 and AC-to-DC power
converters may be substantially identical for both the HP spool 26 and the LP spool 28;
therefore, only the HP side of the left engine system 42 will be described in detail in
FIG 7 for the sake of brevity. The ATU integrated starter-generator 56 can have six secondary windings 146a
^ to 146f connected in associated duos to one of the taps 104a to 104c on the main
windings 98a to 98c. In the illustrated embodiment, the primary windings 98a to 98c are
arranged in a Wye configuration, with the overall configuration of integrated ATU being i
a fork connected configuration. Alternatively, the primary windings 98a to 98c can be
arranged in a Delta configuration.
The nine phase power output 142 is delivered by conductors 148a to 148i and 150a to 150c to the rectifier device 82. The conductors 148a, 148c, and 148e are
i
connected to the second rectifier bridge 114 and the conductors 148b, 148d, 148f are j
connected to the third rectifier bridge 118. Conductors 150a to 150c extend from
primary windings 98a to 98c, and are connected to the first rectifier bridge 110. The
12 !
i
conductors 148a to 148i and 150a to 150c can be lead wires. The remaining rectification I
and filtering of the power is the same as described above for FIG. 3. Although the illustrated integrated starter-generator 56 is shown as having a f
pulse count of eighteen, the starter-generator 56 can be configured to have other pulse f
counts. For example, by providing one secondary winding 146 instead of two, a
generator with a pulse count of twelve can be provided. In another example, by
providing three secondary windings 146 instead of two, a generator with a pulse count 'i
of twenty-four can be provi ded. FIG. 8 is an electrical diagram of the stator winding for the ATU section 62 of
the ATU integrated starter-generator 56 from FIG. 7. As discussed above, each main
© winding 98a to 98c extends from the common neutral point 102 to one of the taps 104a
to 104c. The secondary windings 146a and 146b on the first main winding 98a extend
from the tap 104a, also shown as terminal Al, to a terminal A2 and A3, respectively.
The secondary windings 146c and 146d on the second main winding 98b extend from
the tap 104b, as shown as terminal Bl, to a terminal B2 and B3, respectively. The
secondary windings 146e and 146f on the third main winding 98c extend from the tap
104c, also shown as terminal CI, to a terminal C2 and C3, respectively.
FIG. 9 is a winding vector diagram for the stator winding for the ATU section 62
of the ATU integrated starter-generator 56 of FIG 8. The winding vector diagram can
be used to design the stator winding for the ATU section 62 of the ATU integrated
starter-generator 56. The stator winding is illustrated herein as having a pulse count of
eighteen, although the stator winding can also be configured to have a pulse count in
W other multiple of six, such as 12, 18, 24, etc.
As can be seen, the vector diagram includes nine main vectors Al, A2, A3, Bl,
B2, B3, CI, C2, C3 emanating from a common point of origin O, which corresponds to the neutral point 102 of the stator winding in FIG 8. The main vectors A1-C3 represent
the phase outputs which are delivered by conductors 148a-f and 150a-c to the rectifier [
i
device 82 in FIG 7. The magnitude or length V of the main vectors A1-C3 represents I
the generated AC voltage and the direction or orientation of each main vector Al -C3 }
represents the phase from 0-360° of the generated AC voltage. As shown herein, the
main vectors A1-C3 can have the same length V, but differ in phase by an angle a.
13
I
s
i
Each of the main vectors Al, B1, and C1 includes two sub-vectors XI, X2, Yl, |
Y2, Zl, Z2 emanating from an end point E (which corresponds to the taps 104a-c in
FIG 8) to meet one of the other main vectors A2, A3, B2, B3, C2, C3. The distance !
between the common point of origin O and end point E is represented as length LI. As such, the length V of the main vector Al, and, therefore, all the other main vectors A2, !
A3, B2, B3, C2, C3 is given by the following relationship:
V = llll |
Sub-vector X2 extends from main vector Al to main vector A3 at an angle 0 and [
has a length L2. While not shown in FIG. 9, the other sub-vectors X2, Yl, Y2, Zl, Z2
also have a length L2, and extend from the associated main vector at an angle equal to 0. j*»* The lengths LI and L2 and angles 0 and a can be selected to design the stator winding for the ATU section 62 of the ATU integrated starter-generator 56 from FIG 7. The angles 0 and a are dependent on the number of pulses N, and the relationship
therebetween is given by the following equations:
/ 3600 = 1180*—^r} + 2
360
In this example, it can be given that N=l 8. Thus, angle a = 20° and angle 0 =
80°
The length L2 from end point E to the end of main vector A3 is given by the following relationship: i
180
^ |L2| = ZVsin-^
Thus, by knowing the desired number of pulses N and the desired voltage V, the f
main stator winding for the ATU section 62 of the ATU integrated starter-generator 56 from FIG 3 can be designed. j
FIG 10 is a schematic block diagram of an electrical power system architecture 160 according to a third embodiment of the invention. The system architecture 160 may {
be substantially similar to the system architecture 40 shown in FIG. 2; therefore, like J
elements will be referred to using the same reference numerals. One difference between {
the system architecture 160 shown in FIG. 10 and the system architecture 40 shown in I
14
FIG. 2 is that the ATU section 62 includes an AC power output 162 that is supplied to j
an AC bus 164, in addition to the nine phase power output 68. FIG. 11 is an electrical diagram of the ATU integrated starter-generator 56 and j
the first AC-to-DC power converter for use in the electrical power system architecture I
160 of Fig. 10. The ATU integrated starter-generator 56 can be substantially similar to
the ATU integrated starter-generator 56 of the first embodiment shown in FIG 3, with
the exception that additional secondary windings 166a to 166c are provided on the main j
windings 98a to 98c. The additional secondary windings 166a to 166c can be connected I
by one of the taps 104a to 104c connected to one phase output 106a to 106c of the three I
phase output power supply 66. The phase outputs 106a to 106c are provided to the
J^v three-phase motor-starter controller 96 (FIG 10). The AC power output 162 is
delivered by conductors 168a to 168c from the windings 166a to 166c to the AC bus 164
(FIG. 10) without being converted to DC by the rectifier device 82. The conductors
168a to 168c can be lead wires. The remaining rectification and filtering of the DC
power is the same as described above for FIG. 3.
The system architecture disclosed herein provides an integrated ATU generator
for an aircraft. One advantage that may be realized in the practice of some embodiments
of the described systems and methods is that the traditional high pulse count ATU can I
be eliminated, and its equivalence is integrated into at least one of the generator (s) that s
is connected to a rectifying device to generate a low harmonic content DC output. This
arrangement significantly reduces the weight of the engine, and can simplify the cooling jj
if
for engine components. The provision of the integrated ATU generator can also
^ ^ eliminate the space needed for a separate ATU in the aircraft. j
Another advantage that may be realized in the practice of some embodiments of j
the described systems and methods is that the ATU integrated starter-generator 56 does j
I
not jeopardize the use of the three phase motor-starter controller 96, since the motor- [
starter controller 96 is connected to the three phase power supply 66 before it is
transformed to a nine phase power output in the ATU section 62 of the ATU integrated
starter-generator 56.
Another advantage that may be realized in the practice of some embodiments of (
the described systems and methods is that DC power can be extracted from both spools I
l
26, 28 of a gas turbine engine 10. The operating efficiency of the gas turbine engine 10 j i
|
15 j
I
|
is also increased by seamlessly controlling the power drawn from HP and LP spools 26,
28. In addition to the DC power drawn from the HP and LP spools 26, 28, the DC
outputs 50, 52 from the APU 46 and the EPS 48 can be integrated to provide no break
power transfer (NBPT). '
Another advantage that may be realized in the practice of some embodiments of
the described systems and methods is that the system architecture(s) can offer a level of redundant DC power generation, since DC power can be extracted from the LP spool 28 j
as well as the HP spool 26 of the gas turbine engine 10. Drawing power from both
spools 26, 28 offers increased redundancy for DC power, such that in the event of a
failure of one of the spools 26, 28 or generators 42, 44, DC power may still be extracted
m>s from the remaining operational spool 26, 28 and generator 42, 44. |
Still another advantage that may be realized in the practice of some embodiments [
of the described systems and methods is the avoidance of engine stall issues that are
typically encountered during a descend mode of the aircraft by sharing the DC load !
between the HP and LP spools 26, 28. Being able to draw power from the LP spool as f
well as the HP spool permits allows the aircraft to run at lower rpms during descent I
without risk of stall, thereby preserving fuel efficiency of the aircraft.
Yet another advantage that may be realized in the practice of some embodiments
of the described systems and methods is that both AC and DC power can be extracted
from the gas turbine engine 10. The third embodiment of the invention described herein
in particular provides a system architecture which gives an air framer access to both
types of power, such that an air framer can select either type of power for a particular
W application on an aircraft.
This written description uses examples to disclose the invention, including the
best mode, and also to enable any person skilled in the art to practice the invention, j
including making and using any devices or systems and performing any incorporated i
methods. The patentable scope ofthe invention is defined by the claims, and may
include other examples that occur to those skilled in the art. Such other examples are
intended to be within the scope ofthe claims if they have structural elements that do not
differ from the literal language ofthe claims, or if they include equivalent structural
elements with insubstantial differences from the literal languages ofthe claims.

WE CLAIM:
1. A power generation system for a turbine engine having a pressure spool
comprising:
an AC generator with an integrated auto transformer unit having at least
two three-phase outputs from the integrated auto transformer unit;
a rectifier matrix connected to the at least two three-phase outputs; and
a filter connected to the rectifier matrix configured to provide DC output to
a DC bus.
^ ^ 2. The power generation system of claim 1 wherein the AC generator
comprises a constant frequency generator.
3. The power generation system of claim 1 wherein the AC generator
comprises a variable frequency generator.
4. The power generation system of claim 1 wherein the AC generator
comprises three main windings coupled with a motor starter controller.
5. The power generation system of claim 1 wherein the pressure spool is a
high pressure spool, and the AC generator is coupled with the high pressure spool.
6. The power generation system of claim 5 and further comprising an
^ accessory gearbox having an input mechanically coupled to the high pressure spool and
an output mechanically coupled to the AC generator.
7. The power generation system of claim 1 wherein the pressure spool is a
low pressure spool, and the AC generator is coupled with the low pressure spool.
8. The power generation system of claim 7 and further comprising a constant
speed mechanical drive having an input mechanically coupled to the low pressure spool
and an output mechanically coupled to the AC generator.
17
9. The power generation system of claim 1 wherein the rectifier matrix
comprises a plurality of diodes, and the number of the plurality of diodes is equal to the
desired pulse count of the integrated auto transformer unit.
10. The power generation system of claim 1 wherein the rectifier matrix
comprises three rectifier bridges, where each rectifier bridge is coupled with one of the
phase outputs from the AC generator.
11. The power generation system of claim 1 wherein the AC generator
comprises three three-phase outputs from the integrated auto transformer unit.
12. The power generation system of claim 1, further comprising an additional
^^ winding coupled with the AC generator and configured to provide AC output to an AC
bus.
13. An electrical architecture for a turbine engine having a high pressure (HP)
spool and a low pressure (LP) spool comprising:
a first AC generator coupled to the HP spool and comprising a first
integrated auto transformer unit having at least two three-phase outputs from the first
integrated auto transformer unit;
a second AC generator coupled to the LP spool and comprising a second
integrated auto transformer unit having at least two three-phase outputs from the second
integrated auto transformer unit;
^ . a first AC/DC converter connected to the at least two three-phase outputs
of the first AC generator, and to a first DC bus; and
a second AC/DC converter connected to the at least two three-phase
outputs of the second AC generator, and to a second DC bus;
wherein the first and second DC buses are selectively connected.
14. The electrical architecture of claim 13 v^erein the second AC generator
comprises a constant frequency generator.
15. The electrical architecture of claim 13 wiierein the first AC generator
comprises a variable frequency generator.
18
16. The electrical architecture of claim 13 and further comprising a motor
starter controller, wherein the first AC generator comprises three main windings coupled
with the motor starter controller.
17. The electrical architecture of claim 13 and further comprising a constant
speed mechanical drive having an input mechanically coupled to the LP spool and an
output mechanically coupled to the second AC generator.
18. The electrical architecture of claim 13 and further comprising an accessory
gearbox having an input mechanically coupled to the HP spool and an output
mechanically coupled to the first AC generator.
19. The electrical architecture of claim 13 wdierein the first AC/DC converter
comprises a first rectifier matrix, and the second AC/DC converter comprises a second
rectifier matrix.
20. The electrical architecture of claim 17 wdierein the first AC/DC converter
further comprises a first filter connected to the first rectifier matrix and configured to
provide DC output to the first bus, and the second AC/DC converter further comprises a
second filter connected to the second rectifier matrix and configured to provide DC
output to the second bus.