U.S. patent application number 15/071085 was filed with the patent office on 2016-07-07 for integrated traction system for locomotives.
This patent application is currently assigned to Electro-Motive Diesel, Inc.. The applicant listed for this patent is Electro-Motive Diesel, Inc.. Invention is credited to Madan M. Jalla.
Application Number | 20160194009 15/071085 |
Document ID | / |
Family ID | 56286049 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160194009 |
Kind Code |
A1 |
Jalla; Madan M. |
July 7, 2016 |
INTEGRATED TRACTION SYSTEM FOR LOCOMOTIVES
Abstract
The disclosure an integrated traction system for a locomotive.
The system includes a primary electrical energy source, a traction
load circuit, an auxiliary load circuit, a common DC link, s
secondary electrical energy, and a controller. The electrical
energy generated by the primary electrical energy source is shared
between the traction load circuit and the auxiliary load circuit
during a power mode through the common DC link. Further, the
electrical energy form the secondary electrical energy source is
supplied to the primary electrically energy source during cranking
mode. The controller controls the switching of the integrated
traction system between the two modes.
Inventors: |
Jalla; Madan M.; (Woodridge,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Electro-Motive Diesel, Inc. |
LaGrange |
IL |
US |
|
|
Assignee: |
Electro-Motive Diesel, Inc.
LaGrange
IL
|
Family ID: |
56286049 |
Appl. No.: |
15/071085 |
Filed: |
March 15, 2016 |
Current U.S.
Class: |
105/61 |
Current CPC
Class: |
B61C 5/00 20130101 |
International
Class: |
B61C 3/00 20060101
B61C003/00 |
Claims
1. An integrated traction system for a locomotive, comprising: a
primary electrical energy source operable to provide electrical
energy; a load circuit, including: a traction load circuit adapted
to propel the locomotive; an auxiliary load circuit adapted to
enable one or more auxiliary electrical functionalities associated
with the locomotive; a plurality of electrical energy converters
operable to convert electrical energy to electrical energy with a
desired electrical characteristic; a common Direct Current (DC)
link adapted to provide a common electrical connection between the
primary electrical energy source and each of the traction load
circuit and the auxiliary load circuit; a secondary electrical
energy source configured to feed electrical energy in the load
circuit during a predefined event; and a controller configured to
control the integrated traction system to connect the primary
electrical energy source to the common DC link during a power mode,
and connect the secondary electrical energy source to the primary
electrical energy source during a cranking mode.
Description
TECHNICAL FIELD
[0001] The present disclosure generally relates to an integrated
traction system for a locomotive. More particularly, the present
disclosure relates to a single alternator, to power each of
traction loads and auxiliary loads of the integrated traction
system.
BACKGROUND
[0002] A diesel-electric locomotive typically includes a diesel
engine coupled to drive a traction alternator and an auxiliary
alternator. The traction alternator is adapted to power one or more
traction motors, which typically propel the locomotive. The
auxiliary alternator is adapted to power auxiliary electrical
equipment. Examples of the auxiliary electrical equipment may
include, cooling fans, blowers, air conditioning units, traction
alternator field excitation, battery charging, and light loads.
[0003] In conventional traction systems for locomotives, the
auxiliary alternator consumes substantial space in the locomotive.
Moreover, the auxiliary alternator requires a separate cooling
circuit. This may cause an additional cost to the locomotive.
Additionally, a boost converter is required, at the time of engine
cranking, which may further add to the overall cost of the
locomotive. Thus, it is desirable to provide a traction system, to
drive the traction motors and the auxiliary equipment.
[0004] U.S. Pat. No. 7,256,513, describes a method for controlling
a device connected to an auxiliary power bus of a locomotive.
Although the method of the '513 patent may be effective for
utilizing the energy from an auxiliary alternator, but is cost
intensive and still requires space on the locomotive. In addition,
should a failure event occur that causes a potential failure of the
auxiliary alternators, power from the main alternator may not be
available to run auxiliary electrical equipment.
[0005] The presently disclosed system is directed to overcome one
or more of the problems set forth above.
SUMMARY OF THE INVENTION
[0006] The disclosure provides an integrated traction system for a
locomotive. The integrated traction system includes a primary
electrical energy source operable to provide electrical energy.
Further, the integrated traction system includes a load circuit.
The load circuit includes a traction load circuit and an auxiliary
load circuit. The traction load circuit is adapted to propel the
locomotive and the auxiliary load circuit is adapted to enable one
or more auxiliary electrical functionalities associated with the
locomotive. The load circuit also includes a plurality of
electrical energy converters operable to convert electrical energy
to electrical energy with a desired electrical characteristic. In
addition, the integrated traction system includes a common Direct
Current (DC) link. The common DC link is adapted to provide a
common electrical connection between the primary electrical energy
source and each of the traction load circuit and the auxiliary load
circuit. Further, integrated traction system includes a secondary
electrical energy source. The secondary electrical energy source is
configured to feed electrical energy in the load circuit during a
predefined event. Moreover, integrated traction system includes a
controller. The controller is configured to control the integrated
traction system to connect the primary electrical energy source to
the common DC link during a power mode, and connect the secondary
electrical energy source to the primary electrical energy source
during a cranking mode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a side view of an exemplary locomotive that
illustrates an integrated traction system of the locomotive, in
accordance with the concepts of the present disclosure;
[0008] FIG. 2 is a schematic of an embodiment of the integrated
traction system of FIG. 1 illustrating an arrangement between
various electrical components of the traction system, in accordance
with the concepts of the present disclosure; and
[0009] FIG. 3 is a schematic of another embodiment of the traction
system of FIG. 1 illustrating a Dynamic Brake grid and exciter
battery in the traction system, in accordance with the concepts of
the present disclosure.
DETAILED DESCRIPTION
[0010] Referring to FIG. 1, there is shown a schematic of a general
locomotive 10 including an integrated traction system 12. The
locomotive 10 may be an electrically powered rail vehicle employing
the integrated traction system 12 for propelling the locomotive 10.
The integrated traction system 12 includes a plurality of
mechanical and electrical components that cooperate to propel the
locomotive 10. Any electrically powered vehicle or machine
employing direct current (DC) traction motors for propulsion could
incorporate the integrated traction system 12 with the disclosed
embodiments.
[0011] The integrated traction system 12 includes a prime mover 14
and an alternator/generator set 16. The prime mover 14 may be an
engine, for example, diesel engines, gas turbines, micro-turbines,
sterling engines, fuel cells, spark ignition engines, or
combinations of these. The prime mover 14 may utilize a variety of
fuels such as diesel fuel, natural gas, gasoline or hydrogen. The
alternator/generator set 16 may be an induction alternator, switch
reluctance motor/generator, permanent magnet alternator, or any
synchronous machine of which may receive power from the prime mover
14 by a mechanical shaft connection 18. Further, the
alternator/generator set 16 is electrically connected to a set of
AC traction motors 40 (FIG. 2) for propulsion. According to the
exemplary embodiment illustrated in FIG. 1, the locomotive 10 may
also include multiple pair of wheels 20, with each pair of wheels
20 rotatably coupled to the AC traction motors 40. In one
embodiment, multiple traction motors 40.sub.l to 40.sub.n can be
included in the locomotive 10. In one example, the number of AC
traction motors 40 may depend on the size of locomotive consist.
Furthermore, the integrated traction system 12 includes plurality
of mechanical and electrical components detailed in FIG. 2.
[0012] Referring to FIG. 2, there is shown a schematic of an
embodiment of the integrated traction system 12 of FIG. 1. The
schematic illustrates an arrangement of plurality of mechanical and
electrical components that cooperate to propel the locomotive 10.
The integrated traction system 12 includes a primary electrical
energy source 22. The primary electrical energy source 22 can be an
alternator configured to generate electrical energy. The present
embodiment shows primary electrical energy source 22, which may be
an alternating current (AC) alternator/generator set 16. As
referred to herein, the term "primary electrical energy source"
refers to the AC alternator/generator set 16. The term "primary
electrical energy source" and "AC alternator/generator set" may be
used interchangeably throughout this disclosure. The primary
electrical energy source 22 may include a permanent magnet exciter
24. The permanent magnet exciter 24 may include permanent magnet
mounted on rotor core (not shown) in various pole configurations.
Further, the rotor core is nested within a stator core (not shown)
of a main generator 26. The main generator 26 may include the
stator core and a stator winding (not shown). The stator windings
may be wound on the stator core in various pole configurations. In
operation, the permanent magnet exciter 24 may be rotated to
produce a rotating magnetic field. The rotating magnetic field
interfaces with the stator coils to induce AC current in the stator
coils. The rotating magnetic field coils are excited through the
main generator 26 field excitation chopper circuit. The combined
effect generates an alternating current (AC) of a specific
characteristic in the main generator 26. The characteristic of the
AC is based on the pole configuration and position of the permanent
magnet exciter and the stator winding.
[0013] Further, the main generator 26 may supply alternating
current (AC) to a common direct current (DC) link 30 through a
rectifier 32. In the current embodiment, the main generator 26 of
the primary electrical energy source 22 is configured to provide a
three-phase alternating current (AC) to the common DC link 30
through the rectifier 32.
[0014] The common DC link 30 may be said to include the rectifier
32. The three-phase AC from the the primary electrical energy
source 22 is supplied to the rectifier 32. Thereafter, the
three-phase AC is converted to direct current (DC) through the
rectifier 32. In an illustrative example, the rectifier 32 may
comprise an insulated gate bi-polar transistors (IGBTs). An IGBT is
a three terminal power semiconductor device that combines the
operational characteristics of fast switching of potentially large
current. Other types of rectifier circuits such as diodes and other
Silicone Controlled Rectifiers (SCRs) may be used for the rectifier
32. In one embodiment, the three phase AC from the primary
electrical energy source 22 is received by the common DC link 30
and may be rectified and converted into DC by the rectifier 32 and
further supplied to a load circuit 34.
[0015] The load circuit 34 includes a plurality of electrical
loads. The load circuit 34 is primarily divided into a traction
load circuit 36 and an auxiliary load circuit 38. The common DC
link 30 functions as a common source of DC electrical energy for
the traction load circuit 36 and the auxiliary load circuit 38.
[0016] The traction load circuit 36 may include a set of the AC
traction motors 40. The AC traction motors 40 are coupled with the
pair of wheels 20 of the locomotive 10. In an embodiment, a
plurality of AC traction motors can be included in the traction
load circuit 36. For example, there can be AC traction motor
40.sub.l to 40.sub.n propelling the locomotive 10.
[0017] The auxiliary load circuit 38, in an example, may include a
plurality of auxiliary electrical devices, such as a radiator fan
motor 42, a communication module 44, a heating, ventilating, and
air conditioning (HVAC) motor driven air compressor 46, and other
auxiliary electrical load 48. The auxiliary electrical devices are
exemplary and may include any kind or type of electrical loads,
including electrical lighting loads.
[0018] In another aspect of the disclosure a secondary electrical
energy source 50, such as a storage battery is provided in the
integrated traction system 12 and is electrically connected with
the common DC link 30. In one embodiment, the secondary electrical
energy source 50 may be an energy storage device such as a high
Voltage (HV) battery pack, a bank of capacitors, or combinations of
these. Since, the secondary electrical energy source 50 is
connected to the common DC link 30. The secondary electrical energy
source 50 may be configured to feed electric energy to the load
circuit 34 during a predefined event. For example, in the event
when the energy from the primary electrical energy source 22 is not
sufficient to meet the energy need of the load circuit 34, the
secondary electrical energy source 50 feeds electrical energy at
such predefine event.
[0019] The secondary electrical energy source 50 and the auxiliary
loads 42, 44, 46, and 48 are connected to the common DC link 30. By
way of example, the AC traction motors 40, the auxiliary loads 42,
44, 46, and 48, and the secondary electrical energy source 50 may
be connected to the common DC link 30 via respective electrical
energy convertors 52.
[0020] In one aspect, the AC traction motors 40 may operate a
voltage range of 600-700 V, whereas the radiator fan motor 42 can
operate at a range of 60-75 V. Accordingly, if the voltage level of
the common DC link 30, for powering both the traction load circuit
36 and the auxiliary load circuit 38 is set to a voltage level
appropriate for powering the AC traction motors 40, the auxiliary
equipment may not be able to be directly connected to the common DC
link 30 because the voltage is different from the voltage required
to power the auxiliary equipment. Hence each of the auxiliary load
and the AC traction motors 40 may be individually connected to the
common DC link 30 via the electrical energy convertors 52 operable
to convert electrical energy to electrical energy with a desired
electrical characteristic. The auxiliary load circuit 38 and the
traction load circuit 36 may be individually connected to the
common dc link 30 via a respective DC-AC or DC-DC converters 52,
such as pulse width modulators (PWMs). The electrical energy
convertors 52 are configured to convert the DC power, made
available on the common DC link 30 by the rectifier 32, by
converting AC power generated by the primary electrical energy
source 22. In one embodiment, the electrical energy convertors 52
may be for example inverters, chopper circuits, buck, boost or
buck/boost circuits, rectifiers or DC to DC convertors.
[0021] The electrical energy convertors 52 are depicted as a single
module in FIG. 2, however each electrical load may have individual
converter, such as convertors 52a, 52b, 52c, 52d, and 52e.
Similarly, the secondary electrical energy source 50 could be
connected through a DC/DC converter 52f. However, in practice such
components are typically provided in the form of a
convertor/inverter circuit and a separate convertor/inverter
controller circuit. The electrical energy convertors 52 may be
capable of selectively adjusting the frequency and/or pulse-width
of their respective output to the AC traction motors 40 and
auxiliary loads 42, 46, 44, and 48. Such adjustments enable each of
the loads to operate independently. It is noted that the electrical
energy convertors 52 are capable of bi-directional power flow and
thus may be operated to perform both AC to DC conversion and DC to
AC conversion functions. Thus, the same type of a circuit may be
used to carry out both rectifier functionality and inverter
functionality as discussed herein. For example, the DC/DC convertor
52f may adjust the DC from the common DC link 30 to charge the
battery (secondary electrical energy source 50), and also adjust
the DC output from the battery to supplement electrical energy to
the common DC link 30.
[0022] Further, the integrated traction system 12 includes a
controller 54. The controller 54 is configured to control operating
modes of the integrated traction system 12. In an example, the
controller 54 may include a command module (not shown), and a
sensory module (not shown) to perform various control related
operations of the integrated traction system 12. The controller 54
may also include software which will issue commands to control
operational functions, such as and not limited to operating
switching devices 56a and 56b of the common DC link 30, of the
integrated traction system 12. In an example, the switching devices
56a and 56b can be three pole switch or a bus bar.
[0023] In operation, the controller 54 may determine an operating
mode for the integrated traction system 12. For example, the
sensory module of the controller 54 may be configured to monitor a
condition, such a drawn current in the auxiliary load circuit 38 of
the integrated traction system 12 to determine the operating
mode.
[0024] In one embodiment controller 54 may decide that the
integrated traction system 12 may be operable in a power mode. The
power mode refers to the operating mode when the electrical power
from the primary electrical energy source 22 is consumed to power
the AC traction motors 40 of the traction load circuit 36 and the
auxiliary load circuit 38 via the common DC link 30. For example,
the HVAC compressor 46 may consume electrical energy to condition
the cabin air when powered via the common DC link 30. To enable the
power mode, the controller 54 controls the switching devices 56a
and 56b to connect the primary electrical energy source 22 to the
traction load circuit 36 and the auxiliary load circuit 38 via the
common DC link 30. In other words, the controller 54 closes the
switching devices 56a and 56b.
[0025] In another embodiment, the integrated traction system 12 is
operable in cranking mode. The cranking mode refers to an operating
mode when the primary electrical energy source 22 exits power
generation, and is set to operate as a power consumption device. In
one example, the primary electrical energy source 22 may stop
producing electrical energy and is adjusted to consume electrical
energy for mechanical rotation. The mechanical rotation is
primarily consumed to rotate and crank the prime mover 14 coupled
through the mechanical shaft connection 18. In the cranking mode,
electrical power is provided to the primary electrical energy
source 22 from the secondary electrical energy source 50 that is
the battery, through the respective DC/DC convertor 52f. The
cranking mode is enabled by the controller 54 by flipping the
switching device 56a and closing the switching device 56b, such
that the secondary electrical energy source 50 is connected to the
primary electrical energy source 22 of the integrated traction
system 12. The cranking mode is further described in conjunction
with FIG. 3.
[0026] FIG. 3 illustrates another embodiment of the schematic of
the integrated traction system 12. FIG. 3 illustrates a Dynamic
Brake (DB) grid 58 in the integrated traction system 12. The DB
grid is electrically connected to the common DC link 30 to feed
electrical energy to the traction load circuit 36 and the auxiliary
load circuit 38 through the common DC link 30.
[0027] Generally, electrically powered rail vehicles such as the
locomotive 10 includes the traction load circuit 36 that
selectively activates the AC traction motors 40 during propelling.
However, when the locomotive 10 is retarding or during
deceleration, the power from the prime mover 14 is reduced. In
addition, the locomotive 10 also include conventional friction
brakes and other mechanisms such as regenerative breaking mechanism
for retarding or to decelerate and/or stop the locomotive 10. As
the locomotive 10 decelerates, the momentum of the locomotive 10 is
transferred to the AC traction motors 40 via rotation of the pair
of wheels 20. The AC traction motors 40 acts as a generator to
convert the kinetic energy of the pair of wheels 20 to electrical
energy. This electrical energy is supplied to an electric grid and
usually dissipated as heat via an array of resistors of the DB grid
58. However, to increase the efficiency of the locomotive 10, this
electrical energy may be stored for later use or is partially used
to power the auxiliary loads in the auxiliary circuit 38 such as
42, 46, 44, and 48. Examples of the auxiliary load may include a
radiator fan, a blower motor, a motor driven compressor, an
electric light system, blowers for cooling retarding grids, and the
like.
[0028] In one example, during retarding, AC traction motors act a
generator and generate electrical energy. The electrical energy
generated in the AC traction motors 40 is supplied to the DB grid
58 and is be stored in the secondary electrical energy source 50
for later use or partly used to power the auxiliary load circuit
38. It should be noted that since the DB grid 58 is connected to
the common DC link 30, the electrical energy generated at the DB
grid 58 can be stored and used. This enables increased efficiency
of the locomotive 10 and reduces fuel consumption. Further, the
generated electrical energy at DB grid 58 can also power the
auxiliary load circuit 38. Thus, when the engine is de-rated during
retardation, electrical energy can still be generated to feed the
auxiliary load circuit 38 because the common DC link 30 provides a
common electrical link or connection with the DB grid 58.
[0029] In one embodiment, during the power mode, the electrical
energy from the DB grid 58 can supply additional electrical energy
to the common DC link 30 to charge the secondary electrical energy
sources 50 (battery) or assist in providing electrical energy to
the auxiliary load circuit 38. Whereas, during the cranking mode,
when the primary electrical energy source 22 is not providing
electrical energy, the controller 54 may control the switching
devices 56a and 56b to connect the secondary electrical energy
source 50 or battery to the primary electrical energy source 22.
And, sufficient electrical energy from the secondary electrical
energy source 50 may be diverted to the primary electrical energy
source 22. The electrical energy from the battery may cause the
mechanical rotation and crank the prime mover 14 coupled through
the mechanical shaft connection 18.
[0030] Energy is required to rotate the engine to start the
combustion in the prime mover 14. In the cranking mode, the battery
is connected directly to the primary electrical energy source 22.
The electrical energy stored in the secondary electrical energy
source 50 (battery) and from the DB grid 58, through a convertor
52g and a field chopper circuit 52h provides electrical energy to
the permanent magnet exciter 24 and the stator winding of the main
generator 26, which turn the main generator 26 to act as a motor
and thereby cranks the prime mover 14.
INDUSTRIAL APPLICABILITY
[0031] The locomotive 10 may be an electrically powered rail
vehicle employing an integrated traction system 12 for propelling
the locomotive 10. In operation, electrical energy is generated by
powering the primary electrical energy source 22 via the prime
mover 14. This electrical energy is fed into the common DC link 30,
which acts as common electrical power source for the traction load
circuit 36 and the auxiliary load circuit 38. The traction load
circuit 36 powers the AC traction motors 40 to propel the
locomotive 10. The auxiliary load circuit 38 includes a plurality
of electrical loads, which also consume electrical energy off the
common DC link 30. Hence, all the electrical energy provided by the
primary electrical energy source 22 is converted into DC electrical
energy through the common DC link 30 and is supplied both to the
traction load circuit 36 and the auxiliary load circuit 38. In such
arrangement, the common DC link 30 acts as a common energy source
for the traction load circuit 36 and the auxiliary load circuit
38.
[0032] The common DC link 30 eliminates need for separate
electrical power source say an alternator for the auxiliary load
circuit 38. Also, the primary electrical energy source 22 may be
sized and rated for the maximum power needed to be supplied to
respective components in the traction load circuit 36 and the
auxiliary load circuit 38, considering the available electrical
energy available from the secondary electrical energy source 50 and
the DB grid 58. Hence, the primary electrical energy source 22 may
take up less space than the space required to house the individual
alternators and may require less maintenance and may be less
expensive than providing separate electrical energy source for the
individual circuit.
[0033] It should be understood that the above description is
intended for illustrative purposes only and is not intended to
limit the scope of the present disclosure in any way. Thus, one
skilled in the art will appreciate that other aspects of the
disclosure may be obtained from a study of the drawings, the
disclosure, and the appended claim.
* * * * *