U.S. patent number RE40,713 [Application Number 09/853,852] was granted by the patent office on 2009-05-19 for turbogenerator/motor controller.
This patent grant is currently assigned to Capstone Turbine Corporation. Invention is credited to Everett R. Geis, Brian W. Peticolas.
United States Patent |
RE40,713 |
Geis , et al. |
May 19, 2009 |
Turbogenerator/motor controller
Abstract
A turbogenerator/motor controller with a microprocessor based
inverter having multiple modes of operation. To start the turbine,
the inverter .[.connects to and.]. supplies fixed current, variable
voltage, variable frequency, AC power to the permanent magnet
turbogenerator/motor, driving the permanent magnet
turbogenerator/motor as a motor to accelerate the gas turbine.
During this acceleration, spark and fuel are introduced in the
correct sequence, and self-sustaining gas turbine operating
conditions are reached. The inverter is then .[.disconnected from
the permanent magnet generator/motor,.]. reconfigured to a
controlled 60 hertz mode, and then either supplies regulated 60
hertz three phase voltage to a stand alone load or phase locks to
the utility, or to other like controllers, to operate as a
supplement to the utility. In this mode of operation, the power for
the inverter is derived from the permanent magnet generator/motor
via high frequency rectifier bridges. The microprocessor monitors
turbine conditions and controls fuel flow to the gas turbine
combustor.
Inventors: |
Geis; Everett R. (Orange,
CA), Peticolas; Brian W. (Redondo Beach, CA) |
Assignee: |
Capstone Turbine Corporation
(Chatsworth, CA)
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Family
ID: |
25450994 |
Appl.
No.: |
09/853,852 |
Filed: |
May 11, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
08924966 |
Sep 8, 1997 |
05903116 |
May 11, 1999 |
|
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Current U.S.
Class: |
318/140; 318/145;
318/147; 318/375 |
Current CPC
Class: |
H02P
9/04 (20130101) |
Current International
Class: |
H02P
7/00 (20060101) |
Field of
Search: |
;322/58,10 ;290/52,7
;318/140,145,147,375 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3634328 |
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Apr 1987 |
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DE |
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19704662 |
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Aug 1998 |
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DE |
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0 472 294 |
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Feb 1992 |
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EP |
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0 679 800 |
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Apr 1995 |
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EP |
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0 837 231 |
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Apr 1998 |
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EP |
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0 901 218 |
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Mar 1999 |
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EP |
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6-108879 |
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Apr 1994 |
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JP |
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WO 94/27359 |
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Nov 1994 |
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WO |
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WO 98/25014 |
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Jun 1998 |
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WO |
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WO 99/32762 |
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Jul 1999 |
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WO |
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WO 99/52193 |
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Oct 1999 |
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WO |
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WO 00/28191 |
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May 2000 |
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WO |
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Other References
Japanese Patent Application Abstract entitled "Turbogenerator/Motor
Control System"; filed May 13, 1999, Japanese Serial No.
133003/1999. cited by other .
Japanese Patent Application Abstract entitled "Command and Control
System and Method for Multiple Turbogenerators", filed Oct. 27,
1999, Japanese Serial No. 305375/1999. cited by other .
Japanese Patent Application Abstract entitled "Turbogenerator/Motor
Controller", filed Aug. 4, 1998, Japanese Serial No. 220231/1998.
cited by other .
English Language Abstract for Japanese Patent 6-108879 (Apr. 1994).
cited by other .
German Patent Application Abstract entitled Control Circuit for
Turbine AC Motor-Generator--Monitors Power Supply to Regulate
Secondary Excitation Windings for Constant Operation of Synchronous
Machine, filed Oct. 8, 1986, German Serial No. DE 3634328 (Apr.
1987). cited by other .
German Patent Application Abstract entitled "Load Symmetrising e.g.
for Several Power Supply Modules Including Rectifier
Modules--Involves Checking Each Module to Assess Whether Bus
Functions in Recessive or Dominant Condition," filed Feb. 7, 1997,
German Serial No. DE 19704662 (Aug., 1998). cited by other.
|
Primary Examiner: Masih; Karen
Attorney, Agent or Firm: Waddey & Patterson, P.C.
Beavers; Lucian Wayne
Claims
What we claim is:
1. A method of controlling a permanent magnet turbogenerator/motor
comprising the steps of: providing electrical power to the
permanent magnet turbogenerator/motor through a pulse width
modulated inverter to start the permanent magnet
turbogenerator/motor to achieve self sustaining operation of the
permanent magnet turbo generator/motor; disconnecting the
electrical power from the pulse width modulated inverter once self
sustaining operation of the permanent magnet turbogenerator/motor
is achieved; and reconfiguring the pulse width modulated inverter
to supply voltage from the permanent magnet
turbogenerator/motor.
2. The method of controlling a permanent magnet
turbogenerator/motor of claim 1 wherein the voltage supplied from
the pulse width modulated inverter of the permanent magnet
turbogenerator/motor is utility frequency voltage.
3. The method of controlling a permanent magnet
turbogenerator/motor of claim 1 wherein the pulse width modulated
inverter includes four solid state switching device channels, and
three of the four solid state switching device channels are
reconfigured to supply utility frequency voltage and the fourth
solid state switching device channel is switched at a fifty percent
duty cycle to create an artificial neutral.
4. A method of controlling a permanent magnet turbogenerator/motor
comprising the steps of: providing electrical power to the
permanent magnet turbogenerator/motor through a pulse width
modulated inverter to drive the permanent magnet
turbogenerator/motor as a motor to accelerate the gas turbine
engine of the permanent magnet turbogenerator/motor; providing
spark and fuel to the gas turbine engine of the permanent magnet
turbogenerator/motor during this acceleration to achieve self
sustaining operation of the gas turbine engine; disconnecting the
electrical power from the pulse width modulated inverter once self
sustaining operation is achieved; and reconnecting the pulse width
modulated inverter to the permanent magnet turbogenerator/motor
through a rectifier bridge to reconfigure the pulse width modulated
inverter to supply utility frequency voltage.
5. The method of controlling a permanent magnet
turbogenerator/motor of claim 4 wherein the pulse width modulated
inverter includes four solid state switching device channels, and
three of the four solid state switching device channels are
reconfigured to supply utility frequency voltage and the fourth
solid state switching device channel is switched at a fifty percent
duty cycle to create an artificial neutral.
6. A method of controlling a permanent magnet turbogenerator/motor
comprising the steps of: providing electrical power to the
permanent magnet turbogenerator/motor through a first contactor and
a pulse width modulated inverter to drive the permanent magnet
turbogenerator/motor as a motor through a second contactor to
accelerate the gas turbine engine of the permanent magnet
turbogenerator/motor; providing spark and fuel to the gas turbine
engine of the permanent magnet turbogenerator/motor during this
acceleration to achieve self sustaining operation of the gas
turbine engine; opening the first and second contactors to
disconnect the electrical power from the pulse width modulated
inverter once self sustaining operation is achieved; and
reconnecting the pulse width modulated inverter to the permanent
magnet turbogenerator/motor through a rectifier bridge to
reconfigure the pulse width modulated inverter to supply utility
frequency voltage.
7. The method of controlling a permanent magnet
turbogenerator/motor of claim 6 wherein the pulse width modulated
inverter includes four solid state switching device channels, and
three of the four solid state switching device channels are
reconfigured to supply utility frequency voltage and the fourth
solid state switching device channel is switched at a fifty percent
duty cycle to create an artificial neutral.
8. The method of controlling a permanent magnet
turbogenerator/motor of claim 6 and in addition the step of
connecting the reconfigured pulse width modulated inverter to a
load by closing a third contactor.
9. A method of controlling a permanent magnet turbogenerator/motor
comprising the steps of: providing electrical power to the
permanent magnet turbogenerator/motor through a first contactor and
a multiple solid state switching device channel pulse width
modulated inverter to drive the permanent magnet
turbogenerator/motor as a motor through a second contactor to
accelerate the gas turbine engine of the permanent magnet
turbogenerator/motor; providing spark and fuel to the gas turbine
engine of the permanent magnet turbogenerator/motor during this
acceleration to achieve self sustaining operation of the gas
turbine engine; opening the first and second contactors to
disconnect the electrical power from the multiple solid state
switching device channel pulse width modulated inverter once self
sustaining operation is achieved; reconnecting the multiple solid
state switching device channel pulse width modulated inverter to
the permanent magnet turbogenerator/motor through a high frequency
rectifier bridge to reconfigure the multiple solid state switching
device channel pulse width modulated inverter; and connecting the
reconfigured multiple solid state switching device channel pulse
width modulated inverter to utility power by closing a third
contactor.
10. The method of controlling a permanent magnet
turbogenerator/motor of claim 9 wherein the number of multiple
solid state switching device channels in said pulse width modulated
inverter is four, and three of the four solid state switching
device channels are reconfigured to supply utility frequency
voltage and the fourth solid state switching device channels is
switched at a fifty percent duty cycle to create an artificial
neutral.
11. The method of controlling a permanent magnet
turbogenerator/motor of claim 10 wherein the four solid state
switching device channels are IGBT channels.
12. The method of controlling a permanent magnet
turbogenerator/motor of claim 9 wherein the high frequency
rectifier bridge is a three phase rectifier having three diode
channels.
13. The method of controlling a permanent magnet
turbogenerator/motor of claim 12 wherein each of said three diode
channels include a pair of diodes.
14. A controller for a permanent magnet turbogenerator/motor,
comprising: a pulse width modulated inverter operably associated
with said permanent magnet turbogenerator/motor; means to provide
electrical power to said permanent magnet turbogenerator/motor
through said pulse width modulated inverter to start said permanent
magnet turbogenerator/motor to achieve self sustaining operation of
said permanent magnet turbogenerator/motor; means to disconnect the
electrical power from said pulse width modulated inverter once self
sustaining operation of said permanent magnet turbogenerator/motor
is achieved; and means to reconfigure said pulse width modulated
inverter to supply voltage from said permanent magnet
turbogenerator/motor.
15. The controller for a permanent magnet turbogenerator/motor of
claim 14 wherein said pulse width modulated inverter includes a
plurality of solid state switching device channels.
16. A controller for a permanent magnet turbogenerator/motor,
comprising: a pulse width modulated inverter operably associated
with said permanent magnet turbogenerator/motor, said pulse width
modulated inverter having four solid state switching device
channels; means to provide electrical power to said permanent
magnet turbogenerator/motor through said pulse width modulated
inverter to start said permanent magnet turbogenerator/motor to
achieve self sustaining operation; means to disconnect the
electrical power from said pulse width modulated inverter once self
sustaining operation of said permanent magnet turbogenerator/motor
is achieved; and means to reconfigure said pulse width modulated
inverter to supply voltage from said permanent magnet
turbogenerator/motor, and three of the four solid state switching
device channels are reconfigured to supply utility frequency
voltage and the fourth solid state switching device channel is
switched at a fifty percent duty cycle to create an artificial
neutral.
17. The controller for a permanent magnet turbogenerator/motor of
claim 16 wherein said four solid state switching device channels
are IGBT channels.
18. The controller for a permanent magnet turbogenerator/motor of
claim 14 wherein the voltage supplied from said pulse width
modulated inverter associated with said permanent magnet
turbogenerator/motor is utility frequency voltage.
19. A controller for a permanent magnet turbogenerator/motor having
a gas turbine engine, comprising: a pulse width modulated inverter
operably associated with said permanent magnet
turbogenerator/motor; means to provide electrical power to said
permanent magnet turbogenerator/motor through said pulse width
modulated inverter to drive said permanent magnet
turbogenerator/motor as a motor to accelerate said gas turbine
engine of said permanent magnet turbogenerator/motor; means to
provide spark and fuel to said gas turbine engine of said permanent
magnet turbogenerator/motor during this acceleration to achieve
self sustaining operation of said gas turbine engine; means to
disconnect the electrical power from said pulse width modulated
inverter and said permanent magnet turbogenerator/motor once self
sustaining operation of said gas turbine engine is achieved; a
rectifier bridge operably associated with said pulse width
modulated inverter and said permanent magnet turbogenerator/motor;
and means to reconnect said pulse width modulated inverter to said
permanent magnet turbogenerator/motor through said rectifier bridge
to reconfigure said pulse width modulated inverter to supply
utility frequency voltage.
20. The controller for a permanent magnet turbogenerator/motor
having a gas turbine engine of claim 19 wherein said pulse width
modulated inverter includes four solid state switching device
channels, and three of the four solid state switching device
channels are reconfigured to supply utility frequency voltage and
the fourth solid state switching device channel is switched at a
fifty percent duty cycle to create an artificial neutral.
21. A controller for a permanent magnet turbogenerator/motor having
a gas turbine engine and a permanent magnet generator/motor,
comprising: a pulse width modulated inverter operably associated
with said permanent magnet turbogenerator/motor, said pulse width
modulated inverter having a plurality of solid state switching
device channels; a first contactor operably associated with said
pulse width modulated inverter; a second contactor .[.operable.].
.Iadd.operably .Iaddend.associated with said .[.the.]. permanent
magnet turbogenerator/motor; means to provide electrical power to
said pulse width modulated inverter through said first contactor
when closed to drive said permanent magnet turbogenerator/motor as
a motor through said second contactor when closed to accelerate
said gas turbine engine of said permanent magnet
turbogenerator/motor; means to provide spark and fuel to said gas
turbine engine of said permanent magnet turbogenerator/motor during
this acceleration to achieve self sustaining operation of said gas
turbine engine; means to open said first and second contactors to
disconnect the electrical power from said pulse width modulated
inverter once self sustaining operation is achieved; a rectifier
bridge operable associated with said pulse width modulated inverter
and said permanent magnet turbogenerator/motor; a third contactor
operably associated with said pulse width modulated inverter; means
to reconnect said pulse width modulated inverter to said permanent
magnet turbogenerator/motor through said rectifier bridge to
reconfigure said pulse width modulator inverter; and means to
connect said reconfigured pulse width modulated inverter to supply
utility frequency voltage to a load through said third contactor
when closed.
22. The controller for a permanent magnet turbogenerator/motor of
claim 21 wherein the number of solid state switching device
channels in said pulse width modulate inverter is four, and three
of the four solid state switching device channels are reconfigured
to supply utility frequency voltage and the fourth solid state
switching device channel is switched at a fifty percent duty cycle
to create an artificial neutral.
23. The controller for a permanent magnet turbogenerator/motor of
claim 22 wherein the four solid state switching device channels are
IGBT channels.
24. The controller for a permanent magnet turbogenerator/motor of
claim 21 wherein said rectifier bridge is a three phase rectifier
having three diode channels.
25. The controller for a permanent magnet turbogenerator/motor of
claim 24 wherein each of said three diode channels includes a pair
of diodes.
.Iadd.26. A method of controlling a turbogenerator/motor,
comprising: providing electrical power to the turbogenerator/motor
through an inverter to start the turbogenerator/motor to achieve
self sustaining operation of the turbogenerator/motor; and
reconfiguring the inverter to supply voltage from the
turbogenerator/motor when self sustaining operation of the
turbogenerator/motor is achieved..Iaddend.
.Iadd.27. The method of claim 26, wherein reconfiguring the
inverter comprises: reconfiguring the inverter to supply utility
frequency voltage from the turbogenerator/motor..Iaddend.
.Iadd.28. The method of claim 26, wherein reconfiguring the
inverter comprises: reconfiguring an inverter including four solid
state switching device channels wherein three of the four solid
state switching device channels are reconfigured to supply utility
frequency voltage and the fourth solid state switching device
channel is switched at a fifty percent duty cycle to create an
artificial neutral..Iaddend.
.Iadd.29. The method of claim 26, wherein the turbogenerator/motor
comprises: a permanent magnet turbogenerator/motor..Iaddend.
.Iadd.30. The method of claim 28, wherein the inverter comprises: a
pulse width modulated inverter..Iaddend.
.Iadd.31. The method of claim 26, wherein reconfiguring the
inverter comprises: disconnecting the electrical power from the
inverter when self sustaining operation of the turbogenerator/motor
is achieved..Iaddend.
.Iadd.32. A method of controlling a turbogenerator/motor comprising
the steps of: providing electrical power to the
turbogenerator/motor through an inverter to drive the
turbogenerator/motor as a motor to accelerate the turbine engine of
the turbogenerator/motor; providing spark and fuel to the turbine
engine of the turbogenerator/motor during acceleration to achieve
self sustaining operation of the turbine engine; and reconnecting
the inverter to the turbogenerator/motor through a rectifier to
reconfigure the inverter to supply utility frequency voltage when
self sustaining operation is achieved..Iaddend.
.Iadd.33. The method of claim 32, wherein providing electrical
power through an inverter comprises: providing electrical power
through an inverter including four solid state switching device
channels; and reconnecting the inverter comprises: reconfiguring
three of the four solid state switching device channels to supply
utility frequency voltage; and switching the fourth solid state
switching device channel at a fifty percent duty cycle to create an
artificial neutral..Iaddend.
.Iadd.34. The method of claim 32, wherein the turbogenerator/motor
comprises: a permanent magnet turbogenerator/motor..Iaddend.
.Iadd.35. The method of claim 34, wherein the inverter comprises: a
pulse width modulated inverter..Iaddend.
.Iadd.36. The method of claim 32, wherein reconnecting the inverter
comprises: disconnecting the electrical power from the inverter
when self sustaining operation is achieved..Iaddend.
.Iadd.37. A method of controlling a turbogenerator/motor
comprising: providing electrical power to the turbogenerator/motor
through a first contactor and an inverter to drive the
turbogenerator/motor as a motor through a second contactor to
accelerate the turbine engine of the turbogenerator/motor;
providing spark and fuel to the turbine engine of the
turbogenerator/motor during acceleration to achieve self sustaining
operation of the turbine engine; and reconnecting the inverter to
the turbogenerator/motor through a rectifier to reconfigure the
inverter to supply utility frequency voltage when self sustaining
operation is achieved..Iaddend.
.Iadd.38. The method of claim 37, wherein providing electrical
power through an inverter comprises: providing electrical power
through an inverter including four solid state switching device
channels; and reconnecting the inverter comprises: reconfiguring
three of the four solid state switching device channels to supply
utility frequency voltage; and switching the fourth solid state
switching device channel at a fifty percent duty cycle to create an
artificial neutral..Iaddend.
.Iadd.39. The method of claim 37, further comprising: connecting
the reconfigured inverter to a load by closing a third
contactor..Iaddend.
.Iadd.40. A method of controlling a turbogenerator/motor comprising
the steps of: providing electrical power to the
turbogenerator/motor through a first contactor and a multiple solid
state switching device channel inverter to drive the
turbogenerator/motor as a motor through a second contactor to
accelerate the turbine engine of the turbogenerator/motor;
providing spark and fuel to the turbine engine of the
turbogenerator/motor during acceleration to achieve self sustaining
operation of the gas turbine engine; reconnecting the inverter to
the turbogenerator/motor through a rectifier to reconfigure the
inverter when self sustaining operation is achieved; and connecting
the reconfigured inverter to utility power by closing a third
contactor..Iaddend.
.Iadd.41. The method of claim 40, wherein providing electrical
power through a multiple solid state switching device channel
inverter comprises: providing electrical power through an inverter
including four solid state switching device channels; and
reconnecting the inverter comprises: reconfiguring three of the
four solid state switching device channels to supply utility
frequency voltage; and switching the fourth solid state switching
device channel at a fifty percent duty cycle to create an
artificial neutral..Iaddend.
.Iadd.42. The method of claim 41, wherein the four solid state
switching device channels comprise: IGBT channels..Iaddend.
.Iadd.43. The method of claim 40, wherein the rectifier comprises:
a high frequency three phase rectifier bridge including three diode
channels..Iaddend.
.Iadd.44. The method of claim 43, wherein each of said three diode
channels comprise: two diodes..Iaddend.
Description
TECHNICAL FIELD
This invention relates to the general field of power converting
systems and more particularly to an improved controller for a
turbogenerator/motor.
BACKGROUND OF THE INVENTION
Electric utilities are now grappling with the challenge of
deregulation and competition at a time of relatively slow growth in
electricity demands. While plans for huge power plants are being
shelved because of high costs and environmental concerns, new
customers must still be supplied with electrical power. Existing
plants and transmission lines are simply becoming overwhelmed in
some areas. Nuclear power plants are fast becoming economic
dinosaurs.
One alternative to generating electrical power is called a
"turbogenerator", a small gas turbine engine combined on a common
shaft with an electric generator. When a permanent magnet
generator/motor is utilized, the combination is referred to as a
permanent magnet turbogenerator/motor.
Intake air is drawn through the permanent magnet
turbogenerator/motor by the gas turbine compressor which increases
the pressure of the air and forces it into a recuperator which
receives exhaust gases from the gas turbine. The recuperator
preheats the air before it enters the gas turbine combustor where
the preheated air is mixed with fuel and burned. The combustion
gases are then expanded in the turbine which drives the compressor
and the permanent magnet rotor of the permanent magnet
turbogenerator/motor is mounted on the same shaft as the gas
turbine and compressor. The expanded turbine exhaust gases are then
passed through the recuperator before being discharged from the
turbogenerator/motor.
A permanent magnet turbogenerator/motor generally includes a rotor
assembly having a plurality of equally spaced magnet poles of
alternating polarity around the outer periphery of the rotor or, in
more recent times, a solid structure of samarium cobalt or
neodymium-iron-boron. The rotor is rotatable within a stator which
generally includes a plurality of windings and magnetic poles of
alternating polarity. In a generator mode, rotation of the rotor
causes the permanent magnets to pass by the stator poles and coils
and thereby induces an electric current to flow in each of the
coils. Alternately, if an electric current is passed through the
stator coils, the energized coils will cause the rotor to rotate
and thus the generator will perform as a motor.
A permanent magnet turbogenerator/motor can be utilized to provide
electrical power for a wide range of utility, commercial and
industrial applications. While an individual permanent magnet
turbogenerator may only generate 24 to 50 kilowatts, powerplants of
up to 500 kilowatts or greater are possible by linking numerous
permanent magnet turbogenerator/motors together. Standby power,
peak load shaving power and remote location power are just several
of the potential utility applications which these lightweight, low
noise, low cost, environmentally friendly, and thermally efficient
units can be useful for.
In order to meet the stringent utility requirements, particularly
when the permanent magnet turbogenerator/motor is to operate as a
supplement to utility power, precise control of the permanent
magnet turbogenerator/motor is required.
SUMMARY OF THE INVENTION
.[.The turbogenerator/motor controller of the present invention is
a microprocessor based inverter having multiple modes of operation.
To start the turbine, the inverter connects to and supplies fixed
current, variable voltage, variable frequency, AC power to the
permanent magnet turbogenerator/motor, driving the permanent magnet
turbogenerator/motor as a motor to accelerate the gas turbine.
During this acceleration, spark and fuel are introduced in the
correct sequence, and self-sustaining gas turbine operating
conditions are reached.
At this point, the inverter is disconnected from the permanent
magnet generator/motor, reconfigured to a controlled 60 hertz mode,
and then either supplies regulated 60 hertz three phase voltage to
a stand along load or phase locks to the utility, or to other like
controllers, to operate as a supplement to the utility. In this
mode of operation, the power for the inverter is derived from the
permanent magnet generator/motor via high frequency rectifier
bridges. The microprocessor monitors turbine conditions and
controls fuel flow to the gas turbine combustor.
Since the voltage derived from the permanent magnet generator/motor
is a function of rotational speed and the load, inverter input
voltage requirements limit the operational speed of the gas turbine
from approximately 72,000 rpm to a top speed of 96,000 rpm. The
inverter is direct coupled to the utility, therefor the inverter
voltage rating is established by the utility for grid connect
operation, and has a narrow range for stand along operation..].
.Iadd.In one aspect of the present invention, a turbine generator
system is provided including a turbine engine, a motor/generator
rotationally coupled to the turbine engine for generating AC power
for a load, and a controller connected to the turbine engine for
controlling fuel flow to the turbine engine. The controller
includes microprocessor-controlled switched elements for inverting
internal DC power to output AC power for the load, and is connected
to the motor/generator for applying the output AC power to the
motor/generator at varying voltage and varying frequency to adjust
the motor/generator speed..Iaddend.
.Iadd.In another aspect of the present invention, the controller is
connected to the load for transferring AC power to the load and
includes microprocessor-controlled switched elements for applying
AC power to the motor/generator at varying voltage and varying
frequency to adjust the motor/generator speed..Iaddend.
.Iadd.In yet another aspect of the present invention, the
controller is connected to the turbine engine and includes
microprocessor-controlled switched elements for applying AC power
to the motor/generator to start the turbine engine, and is also
connected to the load for supplying output AC power to the load
after the turbine engine has started..Iaddend.
.Iadd.The controller may include a pulse width modulated inverter
that comprises the microprocessor-controlled switched elements,
which may comprise integrated crate bipolar transistors. The
inverter may further comprise at least one
microprocessor-controlled switched element connected to the
motor/generator for providing an artificial neutral
pole..Iaddend.
.Iadd.The controller may further include control logic connected to
the turbine engine and responsive to a turbine exhaust temperature
for controlling fuel flow to the turbine engine. The controller may
also include control logic connected to the switched elements to
phase lock the output AC power to AC power supplied by at least one
other controller..Iaddend.
.Iadd.The controller may further include a DC bus connected to the
microprocessor-controlled switched elements for transferring the
internal DC power from the motor/generator to the
microprocessor-controlled switched elements. The DC bus may also be
connected to the motor/generator for receiving internal DC power
from the motor/generator, and the microprocessor-controlled
switched elements connected to the DC bus for inverting the
internal DC power to output AC power for the load..Iaddend.
.Iadd.In another aspect of the present invention, a controller is
provided for controlling a motor/generator driven by a turbine
engine, the controller comprising a plurality of
microprocessor-controlled switched elements connected to the
motor/generator for applying power to the motor/generator at
varying voltage and varying frequency to adjust the motor/generator
speed, and a DC bus for transferring rectified DC power from the
motor/generator to an inverter circuit to supply AC power to a
load, the DC bus being connected to the microprocessor-controlled
switched elements for providing DC power to the
microprocessor-controlled switched elements..Iaddend.
.Iadd.In still another aspect of the present invention, a
controller is provided for controlling a motor/generator driven by
a turbine engine, the controller comprising a DC bus connected to
the motor/generator for receiving rectified DC power from the
motor/generator, and a plurality of microprocessor-controlled
switched elements connected to the DC bus for inverting DC power
received from the DC bus to supply AC power to a load..Iaddend.
.Iadd.In yet another aspect of the present invention, a controller
is provided for controlling a motor/generator driven by a turbine
engine, the controller comprising a rectifier circuit connected to
the motor/generator for rectifying AC power from the
motor/generator, and a plurality of microprocessor-controlled
switched elements connected to the rectifier circuit for inverting
DC power from the rectifier circuit to supply AC power to a
load..Iaddend.
.Iadd.In another aspect of the present invention, a controller is
provided for controlling a motor/generator driven by a turbine
engine, the controller comprising a rectifier circuit connected to
the motor/generator for rectifying AC power from the
motor/generator, the rectifier circuit being reconfigurable to
rectify AC power from a power grid, and an inverter including a
plurality of microprocessor-controlled switched elements connected
to the rectifier circuit for inverting DC power from the rectifier
circuit to supply AC power to the power grid, the inverter being
reconfigurable to supply AC power to the
motor/generator..Iaddend.
.Iadd.In another aspect of the present invention, a method is
provided for controlling a system including a motor/generator
rotationally coupled to a turbine engine, the method comprising
connecting a controller to the motor/generator for applying power
to the motor/generator at varying voltage and varying frequency to
adjust the speed of the motor/generator, connecting the controller
to the turbine engine to control fuel flow to the turbine engine,
operating the controller to apply power to the motor/generator to
accelerate the turbine engine to a predetermined speed, initiating
combustion in the turbine engine at the predetermined speed, and
operating the controller to apply power to the motor/generator to
adjust the speed of the motor/generator after initiating combustion
in the turbine engine..Iaddend.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus described the present invention in general terms,
reference will now be made to the accompanying drawings in
which:
FIG. 1 is a perspective view, partially cut away, of a permanent
magnet turbogenerator/motor utilizing .[.the.]. .Iadd.a
.Iaddend.controller .[.of.]. .Iadd.in accordance with .Iaddend.the
present invention;
FIG. 2 is a functional block diagram of the interface between the
permanent magnet turbogenerator/motor of FIG. 1 and .[.the.].
.Iadd.a .Iaddend.controller .[.of.]. .Iadd.in accordance with
.Iaddend.the present invention;
FIG. 3 is a functional block diagram of .[.the.]. .Iadd.a
.Iaddend.permanent magnet turbogenerator/motor controller .[.of.].
.Iadd.in accordance with .Iaddend.the present invention; and
FIG. 4 is a circuit diagram of .[.the.]. .Iadd.a .Iaddend.PWM
inverter .[.of the.]. .Iadd.that may be used with a
.Iaddend.permanent magnet turbogenerator/motor controller .[.of.].
.Iadd.in accordance with .Iaddend.the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
.Iadd.The turbogenerator/motor controller of the present invention
is a microprocessor based inverter having multiple modes of
operation. To start the turbine, the inverter connects to and
supplies fixed current, variable voltage, variable frequency, AC
power to the permanent magnet turbogenerator/motor, driving the
permanent magnet turbogenerator/motor as a motor to accelerate the
gas turbine. During this acceleration, spark and fuel are
introduced in the correct sequence, and self-sustaining gas turbine
operating conditions are reached..Iaddend.
.Iadd.At this point, the inverter is disconnected from the
permanent magnet generator/motor, reconfigured to a control 60
hertz mode, and then either supplies regulated 60 hertz three phase
voltage to a stand alone load or phase locks to the utility, or to
other like controllers, to operate as a supplement to the utility.
In this mode of operation, the power for the inverter is derived
from the permanent magnet generator/motor via high frequency
rectifier bridges. The microprocessor monitors turbine conditions
and controls fuel flow to the gas turbine combustor..Iaddend.
A permanent magnet turbogenerator/motor 10 is illustrated in FIG. 1
as an example of a turbogenerator/motor .[.utilizing the.].
.Iadd.that may be utilized with a .Iaddend.controller .[.of.].
.Iadd.in accordance with .Iaddend.the present invention. .[.The.].
.Iadd.A .Iaddend.permanent magnet turbogenerator/motor 10 generally
.[.comprises.]. .Iadd.includes .Iaddend.a permanent magnet
generator 12, a power head 13, a combustor 14 and a recuperator (or
heat exchanger) 15.
.[.The.]. .Iadd.A .Iaddend.permanent magnet generator 12
.Iadd.generally .Iaddend.includes a permanent magnet rotor or
sleeve 16, having a permanent magnet disposed therein, rotatably
supported within a stator 18 by a pair of spaced journal bearings.
Radial stator cooling fins 25 are enclosed in an outer cylindrical
sleeve 27 to form an annular air flow passage which cools the
stator 18 and thereby preheats the air passing through on its way
to the power head 13.
The power head 13 of the permanent magnet turbogenerator/motor 10
.[.includes.]. .Iadd.will typically include .Iaddend.compressor 30,
turbine 31, and bearing rotor 36 through which the tie rod 29
passes. The compressor 30, having compressor impeller or wheel 32
which receives preheated air from the annular air flow passage in
cylindrical sleeve 27 around the stator 18, is driven by the
turbine 31 having turbine wheel 33 which receives heated exhaust
gases from the combustor 14 supplied with air from recuperator 15.
The compressor wheel 32 and turbine wheel 33 .[.are.]. .Iadd.may be
.Iaddend.rotatably supported by bearing shaft or rotor 36
.[.having.]. .Iadd.which may have .Iaddend.radially extending
bearing rotor thrust disk 37. The bearing rotor 36 .[.is.].
.Iadd.may be .Iaddend.rotatably supported by a single journal
bearing within the center bearing housing while the bearing rotor
thrust disk 37 at the compressor end of the bearing rotor 36
.[.is.]. .Iadd.may be .Iaddend.rotatably supported by a bilateral
thrust bearing. .[.The.]. .Iadd.A .Iaddend.bearing rotor thrust
disk 37 is .Iadd.usually .Iaddend.adjacent to the thrust face at
the compressor end of the center bearing housing while a bearing
thrust plate is .Iadd.typically .Iaddend.disposed on the opposite
side of the bearing rotor thrust disk 37 relative to the center
housing thrust face.
Intake air is drawn through the permanent magnet generator 12 by
the compressor 30 which increases the pressure of the air and
forces it into the recuperator 15. In the recuperator 15, exhaust
heat from the turbine 31 is used to preheat the air before it
enters the combustor 14 where the preheated air is mixed with fuel
and burned. The combustion gases are then expanded in the turbine
31 which drives the compressor 30 and the permanent magnet rotor 16
of the permanent magnet generator 12 which is mounted on the same
shaft as the turbine 31. The expanded turbine exhaust gases are
then passed through the recuperator 15 before being discharged from
the turbogenerator/motor 10.
A functional block diagram of the interface between the generator
controller 40 and the permanent magnet turbogenerator/motor 10 for
stand alone operation is illustrated in FIG. 2. The generator
controller 40 receives power 41 from a source such as a utility to
operate the permanent magnet generator 12 as a motor to start the
turbine 31 of the power head 13. During the start sequence, the
utility power 41 is rectified and a controlled frequency ramp is
supplied to the permanent magnet generator 12 which accelerates the
permanent magnet rotor 16 and the compressor wheel 32, bearing
rotor 36 and turbine wheel 33. This acceleration provides an air
cushion for the air bearings and airflow for the combustion
process. At about 12,000 rpm, spark and fuel are provided and the
generator controller 40 assists acceleration of the turbogenerator
10 up to about 40,000 rpm to complete the start sequence. The fuel
control valve 44 is also regulated by the generator controller
40.
Once self sustained operation is achieved, the generator controller
40 is reconfigured to produce 60 hertz, three phase AC (208 volts)
42 from the rectified high frequency AC output (280-380 volts) of
the high speed permanent magnet turbogenerator 10. The permanent
magnet turbogenerator 10 is commanded to a power set-point with
speed varying as a function of the desired output power. For grid
connect applications, output 42 is connected to input 41, and these
terminals are then the single grid connection.
The functional blocks internal to the generator controller 40 are
illustrated in FIG. 3. The generator controller 40 includes in
series the start power contactor 46, rectifier 47, DC bus
capacitors 48, pulse width modulated (PWM) inverter 49, AC output
filter 51, output contactor 52, generator contactor 53, and
permanent magnet generator 12. The generator rectifier 54 is
connected from between the rectifier 47 and bus capacitors 48 to
between the generator contactor 53 and permanent magnet generator
12. The AC power output 42 is taken from the output contactor 52
while the neutral is taken from the AC filter 51.
The control logic section consists of control power supply 56,
control logic 57, and solid state switched gate drives illustrated
as integrated gate bipolar transistor (IGBT) gate drives 58, but
may be any high speed solid state switching device. The control
logic 57 receives a temperature signal 64 and a current signal 65
while the IGBT gate drives 58 receive a voltage signal 66. The
control logic 57 sends control signals to the fuel cutoff solenoid
62, the fuel control valve 44, the ignitor 60 and release valve 61.
AC power 41 is provided to both the start power contactor 46 and in
some instances directly to the control power supply 56 in the
control logic section of the generator controller 40 as shown in
dashed lines.
Utility start power 41, (for example, 208 AC voltage, 3 phase, 60
hertz), is connected to the start power contactor 46 through fuses
(not shown). The start power contactor 46 may consist of a first
normally open relay and a second normally closed relay, both of
which are de-energized at start up. Alternately, both relays may be
normally open and the control power supply 56 receives input
directly from utility power input 41. Flameproof power resistors
can parallel the relays to provide a reduced current (approximately
10 amps maximum) to slowly charge the internal bus capacitors 48
through the rectifier 47 to avoid drawing excessive inrush current
from the utility.
Once the bus capacitors 48 are substantially charged, (to
approximately 180 VDC, or 80% of nominal), the control power supply
56 starts to provide low voltage logic levels to the control logic
57. Once the control logic microprocessor has completed self tests,
coil power is provided to first normally open relay of the start
power contactor 46 to fully charge the bus capacitors 48 to full
peak line voltage. The bus capacitors 48 can be supplemented for
high frequency filtering by additional film type (dry)
capacitors.
The PWM inverter 49 is illustrated in more detail in FIG. 4. This
inverter 49 illustrates four IGBT channels 70, 71, 72, and 73 each
across the voltage bus V.sub.bus, but as stated previously, these
channels may be any number or type of solid state switching
devices. Each IGBT channel 70, 71, 72, and 73 includes an upper
IGTB 74 and an anti parallel diode 76 and a lower IGBT 78 and an
identical anti parallel diode 76.
The PWM inverter 49 also includes a capacitor channel 48 across the
voltage bus V.sub.busThe capacitor channel 48 includes upper
capacitor 79 and lower capacitor 80 with the midpoint between upper
capacitor 79 and lower capacitor 80 connected to the midpoint of
IGBT channel 70 through inductor 81. The neutral connection N or 68
is at the midpoint of IGBT channel 70 while the midpoints of IGBT
channels 71, 72, and 73 provide output connections A, B, and C,
respectively of output 42. The neutral connection N or 68 may not
be required for all applications.
In addition, the PWM inverter 49 includes a rectifier block channel
54 which is also across the voltage bus V.sub.busThis rectifier
block channel 54 includes a three phase rectifier block 86 having
three (3) diode channels 82, 83, and 84 each including a pair of
diodes 85. The midpoints of each pair of diodes 85 are connected to
generator windings G.sub.A, G.sub.B, and G.sub.C, respectively.
The control logic 57 sequentially drives the IGBT switches of the
PWM inverter 49 via the IGBT gate drives 58. Six of the IGBT
switches, those in channels 71, 72 and 73 are operated at a high
frequency and modulated in classic PWM manner to provide sinusoidal
output via the AC output filter 51. The other 2 IGBT switches of
the PWM inverter 49, both in channel 70, are switched at a 50% duty
cycle to create an artificial neutral 68 and balancing the voltage
on the pair of capacitors 79 and 80. The current in the neutral 68
will consist of a relatively small, high frequency, triangle pulse,
plus whatever 60 hertz component exists as a result of unbalanced
load currents in the 60 hertz generator mode.
The PWM inverter 49 operates in two basic modes: a variable voltage
(0-190 V line to line), variable frequency (0-700 hertz) constant
volts per hertz, three phase mode to drive the permanent magnet
generator/motor 12 for start up or cooldown when the generator
contactor 52 is closed; or a constant voltage (120 V line to
neutral per phase), constant frequency three phase 60 hertz mode.
The control logic 57 and IGBT gate drives 58 receive feedback via
current signal 65 and voltage signal 66, respectively, as the
turbine generator is ramped up in speed to complete the start
sequence. The PWM inverter 49 is then reconfigured to provide 60
hertz power, either as a current source for grid connect, or as a
voltage source.
The AC filter 51 consists of three iron core inductors and three
capacitors to remove the high frequency switching component. The
nominal current for each AC filter inductor will be fundamental
load current at 60 hertz, plus a small high frequency component.
The output of the AC filter 51 is connected to the load via the
output contactor 52 when the PWM inverter 49 is in 60 hertz output
mode. The output contactor 52 is energized from the output of the
PWM inverter 49 via a relay.
The generator contactor 53 connects the permanent magnet generator
12 to the inverter 49 during the start sequence. Initial starting
current approximates nominal operating current for about 2 seconds
then reduces to a lower value for the balance of the acceleration
period. After the start sequence is completed, the generator 12
produces enough output voltage at the output terminals of the
generator rectifier 54 to provide three phase regulated output from
the inverter 49, so both the start contactor 46 and generator
contractor 53 are opened and the system is then self
sustaining.
The IGBT gate drives 58 have five sections, four identical gate
drive circuits with one for each of the four dual IGBT's and
another section consisting of precision resistive (fixed impedance)
voltage dividers with integrated circuit amplifiers. Each gate
drive section consists of two transformer isolated power supplies
driven from a logic level high frequency (-50 kilohertz) driver
circuit, two integrated solid state driver circuits and additional
optical isolators. One circuit operates referenced to the center
point of the two IGBT transistors and the other operates referenced
to the negative bus potential. There are two axial lead high
voltage diodes which provide "on-state" sensing, and signal control
circuits in the event that the associated semiconductor switching
device reflects an "on-state" voltage greater than about 10
volts.
The precision resistive divider circuits consist of two metal film
type fixed resistors connected in series. A low resistive element
provides the low voltage pick-off point, as an example, the
inverter output sensor is typically a -40 to 1 divider for the 120
V RMS inverter output voltage, providing a low voltage reference
signal at the junction of the precision resistive divider circuits.
This signal is buffered by a solid state operational amplifier. In
the event one of the high voltage resistors were to fail shorted,
the other is capable of standing off the voltage and preventing
component damage and/or hazardous conditions from occurring at
other locations within the control logic 57.
The control power supply 56 is really a two stage power converter.
The first stage, consisting of semiconductors and related
components, is a 400 VDC to 24 VDC isolated converter. The
isolation is a function of the transformer and optically isolated
components which link the high voltage side components with the 24
VDC regulated side. The second stage, also consisting of
semiconductors and related components, is a 24 VDC to .+-.12 VDC,
12 VDC, and 5 VDC isolated converter. As with the first stage, the
isolation is a function of the transformer and optically coupled
sensors.
During startup of the permanent magnet turbogenerator/motor 10,
both the start power contactor 46 and the generator contactor 53
are closed and the output contactor 52 is open. Once self sustained
operation is achieved, the start power contactor 46 and the
generator contactor 53 are opened and the PWM inverter 49 is
reconfigured to a controlled 60 hertz mode. After the
reconfiguration of the PWM inverter 49, the output contactor 52 is
closed to connect the AC output 42. The start power contactor 46
and generator contractor 53 will remain open.
The PWM inverter 49 is truly a dual function inverter which is used
both to start the permanent magnet turbogenerator/motor 10 and is
also used to convert the permanent magnet turbogenerator/motor
output to utility power, either sixty hertz, three phase for stand
alone applications, or as a current source device. With start power
contactor 46 closed, single or three phase utility power is brought
through the start power contactor 46 to be able to operate into a
bridge rectifier 47 and provide precharged power and then start
voltage to the bus capacitors 48 associated with the PWM inverter
49. This allows the PWM inverter 49 to function as a conventional
adjustable speed drive motor starter to ramp the permanent magnet
turbogenerator/motor 10 up to a speed sufficient to start the gas
turbine 31.
An additional rectifier 54, which operates from the output of the
permanent magnet turbogenerator/motor 10, accepts the three phase,
up to 380 volt AC from the permanent magnet generator/motor 12
which at full speed is 1600 hertz and is classified as a fast
recovery diode rectifier bridge. Six diode elements arranged in a
classic bridge configuration comprise this high frequency rectifier
54 which provides output power at DC. The rectified voltage is as
high as 550 volts under no load.
The permanent magnet turbogenerator/motor 10 is basically started
at zero frequency and rapidly ramps up to approximately 12,000 rpm.
This is a two pole permanent magnet generator/motor 12 and as a
result 96,000 rpm equals 1,600 hertz. Therefore 12,000 rpm is 1/8th
of that or 200 hertz. It is operated on a constant volt per hertz
ramp, in other words, the voltage that appears at the output
terminals is 1/8th of the voltage that appears at the output
terminals under full speed.
Approximate full speed voltage is 380 volts line to line so it
would be approximately 1/8th of that. When the PWM inverter 49 has
brought the permanent magnet turbogenerator/motor 10 up to speed,
the fuel solenoid 62, fuel control valve 44 and ignitor 60
cooperate to allow the combustion process to begin. Using again the
adjustable speed drive portion capability of the PWM inverter 49,
the permanent magnet turbogenerator/motor 10 is then accelerated to
approximately 35,000 or 40,000 rpm at which speed the gas turbine
31 is capable of self sustaining operation.
The AC filter 51 is a conventional single pass LC filter which
simply removes the high frequency, in this case approximately
twenty kilohertz, switching component. Because the voltage in start
mode is relatively low, its rectified 208 volt line which is
approximately 270 volts, a single bus capacitor 48 is capable of
standing that voltage. However, when in generate mode, the DC
output of the generator rectifier 54 can supply voltages as high as
550 volts DC, requiring two capacitors to be series connected to
sustain that voltage.
The two IGBTs 74 and 78 in IGBT channel 70 function in the generate
mode to form a constant duty fifty percent duty cycle divider to
maintain exactly half bus voltage at the center tap at all times.
That center tap point forms the neutral for the AC output. The
neutral is not required for generator starting but is required for
utility interface. The IGBT channels 71, 72, and 73 form a
.[.classic.]. six transistor PWM inverter.
The reconfiguration of conversion of the PWM inverter 49 to be able
to operate as a current source synchronous with the utility grid
.[.is.]. .Iadd.may be .Iaddend.accomplished by first stopping the
PWM inverter 49. The AC output or the grid connect point is
monitored with a separate set of logic monitoring to bring the PWM
inverter 49 up in a synchronized fashion. The generator contactor
53 functions to close and connect only when the PWM inverter 49
needs to power the permanent magnet turbogenerator/motor 10 which
is during the start operation and during the cool down operation.
The output contactor 52 is only enabled to connect the PWM inverter
49 to the grid once the PWM inverter 49 has synchronized with grid
voltage.
The implementation of the control power supply 56 first drops the
control power supply 56 down to a 24 volt regulated section to
allow an interface with a battery or other control power device.
The control power supply 56 provides the .[.conventional.]. logic
voltages to both the IGBT gate drives 58 and control logic 57. The
IGBT gate drives 58 have two isolated low voltage sources to
provide power to each of the two individual IGBT drives and the
interface to the IGBT transistors is via a commercially packaged
chip.
This system is also capable of generating 480 volt output directly.
By changing the winding in the permanent magnet generator/motor 12,
the voltage ratings of the IGBTs, and the bus capacitors 48, the
system is then capable of operating directly at 480 volts, starting
from grid voltage with 480 volts, and powering directly to 480
volts without requiring a transformer.
While specific embodiments of the invention have been illustrated
and described, it is to be understood that these are provided by
way of example only and that the invention is not to be construed
as being limited thereto but only by the proper scope of the
following claims.
* * * * *