Electric power transmission system for locomotive consists

Abstract

An electric power transmission system for a locomotive consist and a locomotive consist are provided. The locomotive consist includes a first locomotive unit and a second locomotive unit. The electric power transmission system includes a direct current (DC) electrical bus and a control system. The DC electrical bus is connected to each of the first and second locomotive units and is configured to selectively enable transmission of electric power signals between the first and second locomotive units. The control system is operatively connected to the DC electrical bus, the first locomotive unit and the second locomotive unit. The control system is configured to monitor one or more operational parameters associated with the first and second locomotive units and accordingly control the operations of the DC electrical bus based on the monitored parameters.

Description

ELECTRIC POWER TRANSMISSION SYSTEM FOR LOCOMOTIVE CONSISTSCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to U.S. Provisional Patent Application No.63 / 774,334 filed on March 19, 2026, the contents of which are incorporated herein by reference in their entirety.TECHNICAL FIELD

[0002] The present disclosure generally relates to locomotive consists including multiple locomotive units and more particularly, relates to an electric power transmission system for such locomotive consists.BACKGROUND

[0003] Locomotive consists including multiple locomotive units cooperating to function as a single unit have been widely known and used for decades. One example of such locomotive consist is a diesel electric locomotive (DEL) consist that includes a number of diesel locomotive units. These locomotive units are known to be arranged in one or more of a lead and trail configuration or mother-daughter configuration. In the lead and trail configuration, a locomotive operator can control all the locomotive units from a single lead locomotive unit generally positioned at the front of the locomotive consist. In this configuration, electric signals are transmitted between the locomotive units generally over an electrical harness or one or more multi-unit cables while braking controls are achieved using air line interconnections. However, such electrical harnesses do not permit transmission of electrical power exceeding 3 Kilowatts (kW).

[0004] In the mother-daughter configuration, one or more of the locomotive units act as a mother unit and other locomotive units act as the daughter units. The mother locomotive units are independent locomotive units while the daughter locomotive units are only equipped with traction motors and supporting circuitries and depend entirely on the mother locomotive units for all energy requirements. In such configurations, control or communication signals are transmitted over MU cables, braking controls achieved using air lines and electrical power is transmitted over several large electrical wires. Generally, this electrical power is transmitted separately for powering auxiliary systems operating at low voltages, such as by using 74 volts direct current (VDC) signals, for powering high power components by using 3-phase AC signals, and for powering traction motors, such as by using specific propulsion power signals. The propulsion energy is not fixed but regulated in real time based on load and power requirements and distributed directly to the traction motors.CPST Doc: 1388-1940-7389.1

[0005] Another example of locomotive consists is a hybrid locomotive (HL) consist that can include a combination of one or more diesel electric locomotives (DELs) and battery electric locomotives (BELs) that can be arranged in any of the lead and trail, or motherdaughter configurations described above. In this configuration, the traction motors of the BEL unit(s) are repurposed to generate electrical power while regenerative braking, and this electrical power is then used to recharge the battery assemblies of the BEL unit(s). This battery recharge is isolated to each BEL unit.

[0006] All of these electrical power transmission systems are limited in terms of either the type or amount of electrical power that can be transmitted between the individual locomotive units. None of these systems enable transfer of large amounts of power between the locomotive units for general or all-purpose usage, including battery charging, lighting, computers, switchgears, radios, and other electric loads. Moreover, these systems are highly complex and expensive, and even more so if the locomotive consist includes a large number of locomotive units spreading over large distances.SUMMARY

[0007] In one aspect, an electric power transmission system for a locomotive consist is provided. The locomotive consist includes a first locomotive unit and a second locomotive unit. The electric power transmission system includes a direct current (DC) electrical bus and a control system. The DC electrical bus is connected to each of the first and second locomotive units and is configured to selectively enable transmission of electric power signals between the first and second locomotive units. The control system is operatively connected to the DC electrical bus, the first locomotive unit and the second locomotive unit. The control system is configured to monitor one or more operational parameters associated with the first and second locomotive units and accordingly control the operations of the DC electrical bus based on the monitored parameters.

[0008] In a yet another aspect, a locomotive consist for a train is provided. The locomotive consist includes a first locomotive unit and a second locomotive unit connected together for propelling the train. One or more communication cables are connected to each of the first and second locomotive units and are configured to enable transmission of communication and control signals between the first and second locomotive units. A direct current (DC) electrical bus is connected to each of the first and second locomotive units and is configured to selectively enable transmission of electric power signals between the first and second locomotive units. Further a control system is operatively to the communication cables, the DC electrical bus, the first locomotive unit and the second locomotive unit. The control system is configured to monitor one or more operational parameters associated withCPST Doc: 1388-1940-7389.1the first and second locomotive units and accordingly control the operations of the DC electrical bus based on the monitored parameters.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Embodiments will now be described with reference to the appended drawings wherein:

[0010] FIG. 1 illustrates an example locomotive consist including an electric power transmission system, in accordance with an embodiment of the present disclosure.

[0011] FIG. 2 illustrates a simplified block diagram of the electric power transmission system of FIG. 1.

[0012] FIG. 3 illustrates an example block diagram of a control system within the electric power transmission system.

[0013] FIG. 4 illustrates a simplified block diagram of the electric power transmission system, in accordance with a second embodiment of the present disclosure.

[0014] FIG. 5 illustrates a simplified block diagram of the electric power transmission system, in accordance with a third embodiment of the present disclosure.DETAILED DESCRIPTION

[0015] Specific examples of the present systems and methods are described below with reference to the drawings. Details are provided for the purpose of illustration, and the methods and systems can be practiced without some, or all of the features discussed herein. For clarity, technical materials that are known in the fields relevant to the present methods and systems are not discussed in detail.

[0016] The present disclosure relates to an electric power transmission system for distributing electric power to locomotive units within a locomotive consist. To this end, FIG. 1 illustrates an example train 100 including a locomotive consist 102 configured to pull and propel trailing cars 104 (only one shown) on a railway track 101. The locomotive consist 102 includes a plurality of locomotive units, for example, a first locomotive unit 106, a second locomotive unit 108 and a third locomotive unit 110, configured to operate as a single unit to provide the necessary power for driving the train 100, which may require more traction and force than what a single locomotive can provide, such as, over long distances and / or steep gradients. Although FIG. 1 illustrates three locomotive units, it will be understood that the locomotive consist 102 may include fewer or greater number of locomotive units cooperating to achieve similar functionalities.CPST Doc: 1388-1940-7389.1

[0017] In one example, the locomotive consist 102 may be configured in a lead and trail locomotives configuration, in which one of the locomotive units, such as the first locomotive unit 106 positioned at the front of the train 100, may be configured to be the main source of control for the train 100. The trail units may be the additional locomotives, such as the second locomotive unit 108 and the third locomotive unit 110, that may be positioned elsewhere in the train 100, either directly behind the lead locomotive unit 106 or further back in the train 100 and may be configured to provide additional power for pulling the train 100. The lead locomotive unit 106, in this case, may house the operating controls within an operator cabin (not shown), such that a driver controls the various operations of all the locomotive units within the consist 102 and manages the train movements from the lead locomotive unit 106.

[0018] In some alternative implementations, the locomotive consist 102 may be configured in a mother-daughter locomotive configuration (also referred to as slug sets). In this configuration, the mother locomotive unit, say the first locomotive unit 106, may be implemented as a full functional locomotive unit that can operate independently and is equipped with its own power source, traction motor(s), and all the necessary operational controls. The daughter units, such as the second locomotive unit 108 and / or the third locomotive unit 110 cannot operate independently, in that, they are only equipped with traction motors and support circuitries and depend entirely on the mother locomotive unit for all of their electric power requirements. These locomotive configurations are well known in the art and are thus not discussed in greater detail for the sake of simplicity of the present disclosure.

[0019] Further, in one example implementation, the locomotive consist 102 can be embodied as a hybrid locomotive consist that includes a combination of one or more of a diesel electric locomotive (DEL), a battery electric locomotive (BEL), and / or a hybrid locomotive (HL). Such hybrid locomotive consists combine the robustness and range of DELs with the clean and efficient power generation of the BELs or HLs. As shown in FIG. 1, each of the first locomotive unit 106, the second locomotive unit 108, and third locomotive 110 includes a respective power source 120-1, 120-2, 120-3 that generates power to drive corresponding traction motors 122-1, 122-2, 122-3, which in turn rotate the respective wheels 103 to propel the train 100. The DELs can utilize a power source 120 comprising an internal combustion engine, such as a diesel engine to drive an electric generator (or alternator), which in turn produces electric power to power the traction motors 122 connected to the respective locomotive unit’s wheels 103. The BELs can be powered by a power source 120 comprising large onboard batteries that store electrical energy that is used to power the traction motors 122 connected to the respective locomotive unit’s wheels 103. CPST Doc: 1388-1940-7389.1The HLs can be powered by the power source 120 comprising a combination of diesel engine or natural gas engine and other power sources, such as batteries or capacitors or fuel cells and they can switch or combine these power sources to optimize energy usage and reduce emissions. In such a hybrid locomotive consist 102, the DELs can be used as the primary power source for propelling the train 100 in non-electrified tracks or when the train 100 needs to travel long distances beyond the range capability of battery storage capacity of the BELs. On the other hand, the BELs and / or HLs can be used as the primary power sources in urban areas or areas where emissions need to be reduced or when the consist is operating at low speeds, idling, and the like.

[0020] In some alternative implementations, the locomotive consist 102 may be a diesel electric locomotive consist, in which each of the locomotive units 106, 108, and 110 is embodied as a diesel electric locomotive (DEL) using a diesel engine to power the traction motors 122. In a yet another example implementation, each of the locomotive units 106, 108, and 110 may be embodied as either a battery electric locomotive (BEL) or as a hybrid locomotive (HL). These example implementations of the locomotive consist 102 will be described in greater detail in the following description.

[0021] In the example illustrated in FIG. 1, the locomotive consist 102 is a hybrid locomotive consist with the locomotive units 106, 108, and 110 arranged in a lead and trail locomotive configuration. That is, the first locomotive unit 106 acts as the lead locomotive and the second and third locomotive units 108, 110 are the trailing locomotives configured to receive control and operation signals from the lead first locomotive unit 106. Further, the first locomotive unit 106 and the third locomotive unit 110 are implemented as DELs, whereas the second locomotive unit 108 is implemented as a BEL or HL positioned between the DEL locomotive units 106, 110.

[0022] The locomotive consist 102 can be equipped with one or more multi-unit (MU) cables 112-1, 112-2 (collectively referred to as the MU cables 112) connected between the locomotive units 106, 108, 110 and configured to implement a control network between them. In some examples, every pair of locomotive units has its own MU cable connected therebetween and in some other examples, a common MU cable may extend through the entire locomotive consist connecting all the locomotive units thereto. The MU cables 112 enable transmission of control, operational, and communication signals, for example, from the lead first locomotive unit 106 to the other trailing second and third locomotive units 108, 110. This allows all the connected locomotive units 106, 108, and 110 to operate in unison, providing coordinated acceleration, braking, and overall operations. The MU cables 112 can be configured to facilitate transmission of control signals, such as throttle position, brakingCPST Doc: 1388-1940-7389.1and accelerating commands, and / or other operational controls and commands between the locomotive units 106, 108, and 110 to enable the train operator to control all the locomotive units 106, 108, 110 at once, for example, from an operator cabin (not shown) located on the lead first locomotive unit 106. In some examples, the MU cables 112 and the control network of the locomotive consist 102 may be implemented using suitable communication protocols, such as Local Operating Network (LON) or LONWORKS® protocol, to enable the various devices and systems within the locomotive consist 102 to communicate with each other over the MU cables 112.

[0023] The locomotive consist 102 further includes an electric power transmission system 200 configured to manage and control distribution of electric power to various components within and between the locomotive units 106, 108, and 110 of the locomotive consist 102. The electric power transmission system 200 includes the various components and circuitries involved in generation, distribution, and consumption of electric energy within the locomotive consist 102.

[0024] In an embodiment of the present disclosure, the electric power transmission system 200 includes a multi-unit direct current (DC) electrical bus 202 configured to extend between and connect the locomotive units 106, 108, and 110 to selectively enable transmission of electrical power between the locomotive units 106, 108, and 110 for all purpose uses. In one implementation, the multi-unit DC electrical bus 202 is embodied as a multi-unit High-Voltage Direct Current (HVDC) bus that enables efficient transmission of large amounts of electric power over long distances with minimal losses. The DC electrical bus 202 (hereinafter interchangeably referred to as the HVDC bus 202) includes a set of conductors that carry the Direct Current (DC) at high voltage levels between the locomotive units 106, 108, and 110. For example, alternating current (AC) from the power source (i.e., from the traction alternator) in one locomotive unit is rectified, by a power or energy conversion unit, into high voltage DC and then transmitted via the HVDC bus 202 to another one or more of the locomotive units 106, 108, 110 where corresponding inverters and / or converters convert the high voltage DC back to AC or low voltage DC current for general purpose usage. The general or all-purpose usage can include electric energy for propulsion, battery charging, lighting, computers and control systems, radios, switchgear, Heating, Ventilation, and Air Conditioning (HVAC), and other electric loads of the locomotive units 106, 108, 110. The HVDC bus 202 can be implemented as a rigid or semi-rigid conductor (or set of conductors) that can be either in the form of solid bars, pipes, or cables. Further, the HVDC bus 202 is insulated and / or isolated to handle high voltages safely. In some examples, the DC electrical bus 202 is also configured to transmit other signals, such as communication signals that are superpositioned on the high-power transmission.CPST Doc: 1388-1940-7389.1

[0025] In an embodiment, the HVDC bus 202 is regulated to support energy conversion equipment of many types and ranges, for example, from 200 Volts Direct Current (VDC) to 3000VDC. To this end, the electric power transmission system 200 includes or is otherwise associated with a control system 204 that is configured to regulate the voltage and power quality on the HVDC bus 202 to support various equipment connected to it across the locomotive consist 102 and enable transmission of electric power signals at high voltages, such as in the range of 200VDC to 3000VDC. For example, the control system 204 may be configured to control and adjust the operations of the HVDC bus 202 in accordance with one or more power requirement parameters between the locomotive units 106, 108, and 110. The HVDC bus 202 is regulated to ensure that the equipment connected to the HVDC bus 202 operates efficiently and safely. This regulation is important for maintaining system stability, optimizing energy conversion, and protecting the equipment from potential damage due to voltage fluctuations or other electrical disturbances. Thus, the HVDC bus 202 can be implemented to various types of configurations of the locomotive consist 102, such as to Diesel Electric Locomotives (DEL) consists comprising of only DELs, or to Battery Electric Locomotives (BELs) I Hybrid Locomotive (HLs) consists comprising only of BELs / HLs, and / or to hybrid locomotive consists comprising a combination of DELs, BELs, and / or HLs. Further details of the electric power transmission system 200 and its operations will now be described with reference to FIGS. 2 to 5 in the following description.

[0026] Fig. 2 illustrates a simplified block diagram of the example electric power transmission system 200 implemented in the hybrid locomotive consist 102. For the purposes of explanation, FIG. 2 only shows how the components within the first locomotive unit 106, which is a DEL (diesel electric locomotive), and the second locomotive unit 108, which is a BEL (battery electric locomotive), are connected and operate within the consist 102. However, it will be appreciated that the third (DEL) locomotive unit 110 is also connected to the second (BEL) locomotive unit 108 within the locomotive consist 102 in the same manner.

[0027] The first locomotive unit 106 includes a propulsion system 114 that encompasses the various subsystems and components that contribute to the operation, control, and movement of the first locomotive unit 106. The propulsion system 114 includes the power source 120-1 comprising an internal combustion engine 121, such as a diesel engine that utilizes fuels and oils, such as diesel fuel and lubricating oil to generate power used by the various components and subsystems of the first locomotive unit 106 and in some cases, components, and subsystems of the second locomotive unit 108, as will be discussed later in the description. The engine 121 is mechanically connected to a generator 123 (or alternator) configured to convert the mechanical power generated by the engine 121 CPST Doc: 1388-1940-7389.1into electrical power that is then transmitted to the traction motors 122-1 via one or more traction inverters of the locomotive unit 106. The traction motors 122-1 utilize the electrical power to generate mechanical power for rotating the wheels 103, thereby driving the train 100. In some implementations, the traction motors 122-1 may be connected to the generator 123 via a rectification unit 124 that is configured to convert alternating current (AC) power output from the generator 123 into direct current (DC) power suitable for the traction motors 122-1. The electrical connection between the power source 120-1 and the traction motors 122-1 may also include circuit breakers (not shown) that provide electrical safety by automatically interrupting power when the current exceeds safe limits or if there is any other fault event, such as short circuit. An energy storage unit 125 can also be connected to the power source 120-1. The energy storage unit 125 may include, for example, a battery pack, a bank of capacitors, a compressed air storage system with an air motor or turbine, or a combination of these. The energy storage unit 125 can be configured to store electrical energy for later use, such as for power engine start-up functions, provide a power back up for auxiliary systems of the locomotive unit 106, such as lighting, electronic systems, heating, ventilation, and air-conditioning (HVAC) systems, etc., when the primary engine 121 is turned off.

[0028] The propulsion system 114 further includes a braking system 126 configured to achieve safe stopping and / or speed control of the first locomotive unit 106 and the train 100. The braking system 126 can include components such as air or pneumatic brakes, dynamic brakes, or other braking mechanisms to control the wheels 103 and achieve the braking functionality. In one example, the braking system 126 may also include grid resistors that are configured to manage and dissipate energy generated by braking in the form of heat. In case of dynamic braking, the traction motor(s) 122-1 are repurposed as generators when braking is required. Thus, when the locomotive unit 106 is in motion, the momentum of the train drives the traction motors to generate electricity and the grid resistors are used to safely dissipate any excess electrical energy that cannot be used, as heat. In one example implementation, the braking system 126 may be a part of a regenerative braking system implemented in the locomotive consist 102, wherein instead of dissipating the energy as heat, the regenerative braking system feeds the energy generated while braking back into the power supply for recharging the battery systems of, for example, the second (BEL) locomotive unit 108.

[0029] The propulsion system 114 further includes a pneumatic power unit 128, an axle generator 130, a fuel monitoring system 132, a cooling system 134, an exhaust system 135, and one or more auxiliary systems 136.CPST Doc: 1388-1940-7389.1

[0030] The pneumatic power unit 128 is configured to provide pneumatic power (i.e., compressed air) to various systems within the locomotive unit 106 that require pneumatic operations, such as the braking system 126, the suspension systems (not shown), fan drives, cooling, and exhaust system 134, and the like. The pneumatic power unit 128 may include a number of pneumatic components, such as air compressor, control valves, regulators, etc., that operate to enable the pneumatic operations within the locomotive unit 106. The axle generator 130 can be mechanically driven by the rotation of one or more of train’s axles and may be configured to monitor axle speed and related control functions, in some examples. For example, the axle generator 130 may be used as part of systems such as wheel slip control, traction control, etc., for braking and operational safety.

[0031] The fuel monitoring system 132 may be configured to manage, track, and optimize the usage of diesel fuel, which is the primary energy source for the first locomotive unit 106. The fuel monitoring system 132 may include one or more fuel sensors, fuel flow meters, fuel gauges, level sensors, and data acquisition systems to obtain the fuel consumption data, and fuel availability data to generate alerts regarding any leaks, excessive consumptions, or other inefficiencies. The cooling system 134 can include radiators, fans, coolant circuits and the like, and the exhaust system 135 can include exhaust pipes, mufflers, emission control systems, and the like. Furthermore, the auxiliary systems 136 can include for example, lighting systems, heating, ventilation, and air conditioning systems (HVACs), communication systems, and the like, that support the operation of the first locomotive unit 106. These systems are well known in the art and are thus not discussed herein greater detail.

[0032] The first locomotive unit 106 is further equipped with one or more DC / DC converters 137 configured to convert DC power from one voltage level to another level. In one example, the DC / DC converter 137 may be implemented as a high voltage (HV) - 74V DC / DC converter that is configured to convert high voltage DC power to a lower 74 volt DC power output. Such a converter can be used to convert electrical power from the power source 120-1 , the energy storage unit 125 or the HVDC bus 202, in some case, for powering electronic devices and components that operate at this lower voltage, such as lighting, communication systems, and other auxiliary devices that require the 74-volt supply.

[0033] The first locomotive unit 106 further includes an auxiliary power unit (APU) 138, which in some embodiments may be a Hotstart-type APU, configured to maintain engine readiness by keeping the engine’s oil and coolant heated and circulating when the primary engine 121 is shut down and one or more environmental conditions (such as environmental temperature thresholds) are met. For example, the APU 138 ensures that the engineCPST Doc: 1388-1940-7389.1remains warm, facilitating easier startup and reducing wear caused by cold temperatures. In some other examples, the APU 138 may include an electric APU (not shown) that can be configured to generate electrical power autonomously, independent of the primary power source 120-1 , for example, to provide auxiliary electrical power for powering auxiliary systems 136 or when additional power capacity is needed.

[0034] The first locomotive or DEL unit 106 and the propulsion system 114 are operatively connected to and controlled by a local control system 142 (hereinafter the DEL control system 142), which controls the various operations of the locomotive unit 106 to ensure safe, reliable, and efficient operations. The operating controls and electronic components, such as input / out controls associated with the DEL control system 142 may be housed within an operator cabin (not shown) that allow the train operator to operate the locomotive unit 106. In an example embodiment, the DEL control system 142 is embodied as a High-Horsepower (HHP) control system designed for a high-horsepower locomotive, such as the diesel electric locomotive described herein. The DEL control system 142 overseeing the locomotive control and management, may be configured to receive signals from a variety of sources in order to estimate locomotive operating parameters. The DEL control system 142 may be further linked to an output device, such as a display device (not shown) to provide a user interface, through which the train operator can provide inputs and receive outputs related to the operation of the first locomotive unit 106. The DEL control system 142 may be configured to optimize engine 121 performance and fuel efficiency, manage distribution of power to the traction motors 122-1 , provide diagnostics and monitoring, and enable communication between the first locomotive unit 106 and external systems, such as the central control system 204 of the locomotive consist 102.

[0035] Other than the DEL locomotive unit 106, the locomotive consist 102 includes the second locomotive unit 108 that is implemented as a battery electric locomotive (BEL). Although the second locomotive unit 108 is shown and described as a BEL unit, it will be appreciated that in other implementations, the second locomotive unit 108 can be implemented as a hybrid locomotive (HL) in a similar manner.

[0036] The second locomotive unit 108 includes a second propulsion system 116 that encompasses the various subsystems and components that contribute to the operation, control, and movement of the second locomotive unit 108. The propulsion system 116 include a set of one or more large batteries (or battery assembly) configured to function as the primary power source 120-2 for the second locomotive unit 108. These batteries can be implemented as high-capacity lithium ion batteries in some examples, or as other types of advanced battery technologies, in some other examples. The power source 120-2 may alsoCPST Doc: 1388-1940-7389.1include a battery management system (not shown) configured to monitor battery health, manage charging and discharging processes, and ensure safety by preventing conditions such as overcharging or thermal runaway.

[0037] The second locomotive unit 108 may include its own respective traction motor(s) 122-2 and braking system(s) 146 configured to operate to drive and stop the second locomotive unit 108. The power source 120-2 is configured to be connected to the traction motors 122-2 and the braking systems 146 of the locomotive unit 108 via a DC / DC converter 144. The DC / DC converter 144 can be configured to adjust voltage output from the power source 120-2 to the voltage levels required by the traction motors 122-2. In some alternative implementations, the traction motors 122-2 may be controlled by inverters, such as the 480V 3-phase inverter configured to convert the DC power from the power source 120-2 to AC output suitable for powering the traction motors 122-2.

[0038] Further, in an example implementation, the braking system 146 of the second locomotive unit 108 may utilize the regenerative braking system, wherein the traction motors 122-2 are repurposed for generating electric power while braking, which is then fed back to recharge the batteries of the power source 120-2, thereby enhancing the overall energy efficiency of the second locomotive unit 108. Additionally, the locomotive unit 108 may also incorporate other braking technologies, such as pneumatic braking, blended braking (which uses a combination of regenerative and pneumatic braking), and may be equipped with grid resistor(s) to dissipate any excess energy as heat in a similar manner as described above for braking systems 126 of the first locomotive unit 106.

[0039] Similar to the first locomotive unit 106, the second locomotive unit 108 may also include an axle generator 148 which is mechanically driven by the rotation of one or more of train’s axles. In an example implementation, the second locomotive unit 108 is further configured to support shore power charging when the train 100 is stationary, for example, at an electrical charging facility. To that end, the locomotive unit 108 may include one or more onboard power charging systems 150 that can be connected to an external charging station, such as power grids 152 at designated charging facilities, such as train depots or stations to recharge the batteries onboard the second locomotive unit 108. The charging systems 150 may connect the power grid 152 to the batteries via the DC / DC converter 144 that adjusts the voltage from the power grid 152 or shore power to the levels suitable for charging the onboard batteries of the second locomotive unit 108. In some examples, the locomotive units can be equipped with one or more alternators I generators in addition to the traction alternator / main generator to function as the axle generators 130, 148.CPST Doc: 1388-1940-7389.1

[0040] The second locomotive unit 108 and the second propulsion system 116 can be operatively connected to and controlled by an onboard local control system 154, hereinafter referred to as the BEL control system 154. In one example, the BEL control system 154 may be embodied as an electric-vehicle (EV) control system. The BEL control system 154 can be operatively connected to the various systems and components of the second locomotive unit 108 and configured to control the various operations of the second locomotive unit 1108 to ensure safe, reliable, and efficient operations of the second locomotive unit 108. For example, the BEL control system 154 may be configured to optimize the batteries’ performance and energy efficiency, manage distribution of power to the traction motors 122-2, provide diagnostics and monitoring, and enable communication of the BEL unit 108 with external systems, such as the central control system 204 of the locomotive consist 102.

[0041] The first locomotive or DEL unit 106 and the second locomotive or BEL unit 108 are connected to each other by the MU cables 112 that enable transmission of communication and control signals between the two to propagate the control network for operating the locomotive consist 102. In some examples, the control network and the communication signals are transmitted over the MU cables 112 using a communication protocol, including but not limited to, LONWORKS® protocol, which is implemented to manage and optimize control and operation of the locomotive consist 102. As explained above, the control signals, such as throttle positions, braking and accelerating commands, etc., are transmitted over the MU cables 112 from the first locomotive unit 106 to the second locomotive unit 108. This way, one train driver can control the entire locomotive consist 102 by sending control signals over the MU cables 112 from the operator cabin positioned on only one of the locomotive units, i.e., the first locomotive unit 106 in this example.

[0042] In an embodiment of the present disclosure, the first locomotive unit 106 and the second locomotive unit 108 are electrically coupled via the multi-unit DC electrical bus 202, which is implemented as a multi-unit high-voltage direct current (HVDC) bus, hereinafter referred to as the HVDC bus 202. The HVDC bus 202 may include a set of conductors that enable transmission of electric power signals at high voltages between the locomotive units 106, 108, and 110. HVDC systems utilize converters at both the transmission and reception ends to step up and step down the voltage for transmission and distribution. High voltage transmission minimizes the current for a given power level, thereby reducing the heat losses in conductors, and enabling transmission of electric power signals over vast distances. Moreover, because of lower current, the HVDC bus 202 can utilize thin conductors, thereby reducing materials and costs, and simplifying the designs of the power transmission lines between the locomotive units 106, 108, and 110 in the locomotive consist 102.CPST Doc: 1388-1940-7389.1

[0043] The HVDC bus 202 may be a part of an HVDC system 210 that encompasses the setup and components required for transmitting electrical power over long distances, such as between the locomotive units 106, 108, and 110 in this example. To that end, the HVDC system 210 includes one or more converters needed to convert power from AC to DC and vice-versa, one or more converters needed to step up / down the voltage of the electrical power, and the HVDC bus 202 for transmitting the high-voltage DC power signals to various components between the locomotive units 106, 108, and 110.

[0044] To that end, as shown in FIG. 2, the AC power output from the power source 120-1 of the first locomotive unit 106 is filtered by a LC filter 156 configured to filter unwanted frequencies from the signal. The LC filter 156 may include a combination of one or more inductors and capacitors that can allow certain frequencies to pass while blocking others. The permissible frequencies can be predefined based on the locomotive unit’s requirements. The filtered electric power signal from the LC filter 156 can be used to power various onboard systems and auxiliary loads, including the Hotstart type APU 138.

[0045] In some cases, the second locomotive unit 108 may need to receive power supply from the first locomotive unit 106, such as for powering the traction motors 122-2 or for charging batteries 120-2. In such cases, the power generated by the power source 120-1 of the first locomotive unit 106 is transmitted over the HVDC bus 202 to the second locomotive unit 108. To that end, the electric power signal from the power source 120-1 is first filtered by the LC filter 156 and passed through a first power conversion unit 158, which is configured to convert the power signal into DC current at high voltage for transmission over the HVDC bus 202. At the second locomotive unit 108, a second power conversion unit 160 converts the high voltage DC signal from the HVDC bus 202 into a different voltage AC or DC signal for further usage.

[0046] In an example implementation, the first power conversion unit 158 may include one or more bidirectional AC / DC converters and DC / DC converters. The bidirectional AC / DC converters may be configured to convert the AC power signal from the power source 120-1 into DC power signal and vice-versa. The DC / DC converter may be configured to step up (boost) or step down (buck) the voltage of the DC power signal output either for transmission over the HVDC bus 202 or for receiving the power signal from the HVDC bus 202. In this example, to transmit the power signal over the HVDC bus 202, the DC / DC converter within the first power conversion unit 158 may step up the voltage of the DC current to a desired voltage level, such as in a range of 200VDC to 3000VDC, suitable for transmission over the HVDC bus 208. The second power conversion unit 160 may similarly include its own DC / DC converter configured to adjust the voltage of the received power signal from the HVDC busCPST Doc: 1388-1940-7389.1202 to suitable voltage levels required for recharging the battery assembly within the power source 120-2. These power conversion units 158, 160 may also include one or more circuit breakers to protect the locomotive units 106, 108 in case of any electrical faults by interrupting the power flow.

[0047] Each of these power conversion units 158 and 160 within the first locomotive unit 106 and the second locomotive unit 108, respectively, are operatively connected to and controlled by the central control system 204, which monitors, in real-time, the power requirements and voltage requirements across the locomotive units 106, 108 and adjusts, in real-time, the operations of the power conversion units 158, 160 as needed based on the monitored requirements. Further details of the central control unit 204 will be described later in the following description.

[0048] Further, in some examples, such as when the first locomotive unit 106 is turned off to reduce emissions and the second locomotive unit 108 primarily drives the train 100, the DC / DC converter 137 in the first locomotive unit 106 may be configured to be powered by the HVDC bus 202 to enable powering auxiliary systems 136 of the first locomotive unit 106. In this mode, the electric power signal from the batteries or the power source 120-2 may be stepped up by the second power conversion unit 160 of the second locomotive unit 108 to be transmitted over the HVDC bus 202 and subsequently to the DC / DC converter 137 and associated auxiliary systems. In some implementations, a third power conversion unit 162 may be provided in the first locomotive unit 108 upstream of the DC / DC converter 137. The third power conversion unit 162 may be configured to step down the voltage of the power signal from the HVDC bus 202 to a voltage suitable for powering the DC / DC converter 137 for further distribution.

[0049] Referring to FIG. 3, the central control system 204 includes or is otherwise associated with an input unit 302, an output or display unit 304, a memory unit 306, a communication interface 308 and a processor 310. It will be appreciated by those of ordinary skill in the art that FIG. 3 depicts the control system 204 in a simplified manner and that other practical implementations can include fewer or additional components and suitably configured logic to support known or conventional operating features that are not described in detail herein.

[0050] The input unit 302 enables the control system 204 to receive inputs, for example, from one or more sensors positioned in the locomotive units 106, 108, 110, the DEL control system 142 and the BEL control system 154. The input unit 302 may also enable the control system 204 to receive instructions and provide output to the local control systems, such as the DEL and BEL control systems 142, 154, of each of the locomotiveCPST Doc: 1388-1940-7389.1units 106, 108, 110. The input unit 302 also enables the control system 204 to receive inputs, such as user commands via one or more input devices (e.g., keyboards, touchscreen displays, mouse, etc.). The output or display unit 304 may be configured to provide outputs, for example, in the form of control signals to one or more components of the locomotive units 106, 108, 110 and the HVDC bus 202. The output unit 304 may also provide output, such as performance reports, diagnostic reports, and the like to one or more output devices (e.g., display device, graphical user interfaces (GUI) displayed on the device, etc.) provided in the operator cabin of the first locomotive unit 106 to permit the train operator to monitor and control operations of the locomotive units 106, 108, 110.

[0051] The memory unit 306 can include any of the volatile memory elements (e.g., random access memory (RAM), nonvolatile memory elements (e.g., read-only memory (ROM)), and / or combinations thereof. Further, the memory unit 306 can incorporate electronic, magnetic, optical, and / or other types of storage media, including non-transitory computer readable media. It can be appreciated that the memory unit 306 can have a distributed architecture, where various components are situated remotely from one another, and are accessed by the control system 204, and its components, such as the processor 310. The memory unit 306 can include one or more software programs, each of which includes listing of computer executable instructions for implementing logical functions. The software in the memory unit 306 can include a suitable operating system and one or more programming codes for execution by the components, such as the processor 310 of the control system 204. The operating system can be configured to control the execution of the programming codes and provide scheduling, input-output control, file and data management, memory management, and communication control, and related services. The programming codes can be configured to implement the various processes, algorithms, methods, techniques, etc. described herein.

[0052] The components of the control system 204 can communicate internally and externally with other components of the locomotive units 106, 108, 110 via the communication interface 308. The communication interface 308 can include, but is not limited to, one or more buses or other wired or wireless connections, as is known in the art. The communication interface 308 can have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers, among many others, to enable communications. Further, the communication interface 308 can include address, control, and / or data connections to enable appropriate communications among the aforementioned components. The communication interface 308 also enables the control system 204 to communicate with the other components of the locomotive units 106, 108, 110, such as the DEL control system 142, the BEL control system 154, the HVDC bus CPST Doc: 1388-1940-7389.1202, and the MU cables 112. In some implementations, the communication interface 308 can include a transceiver configured to transmit and receive data to / from various devices / machines operating during the oil and gas production processes. The transceiver can transmit and receive data / messages in accordance with various communication protocols, such as, TCP / IP, UDP, and 2G, 3G, 4G, 5G or6G communication protocols. Further, the communication interface 506 can also include, for example, an Ethernet card or adapter or a wireless local area network (WLAN) card or adapter. Additionally, or alternatively, the communication interface 308 can include a radio frequency interface for wide area communications such as Long-Term Evolution (LTE) networks, or any other networks known in the art.

[0053] The processor 310 can be a hardware device for executing software instructions, such as the software instructions stored in the memory unit 306. The processor 310 can include one or more of a custom made or commercially available processor, a central processing unit (CPU), an auxiliary processor among several processors associated with the processor 310, a semiconductor-based microprocessor, or generally any device for executing software instructions. The processor 310 can be implemented using one or more controller technologies, such as Application Specific Integrated Circuit (ASIC), Reduced Instruction Set Computing (RISC) technology, Complex Instruction Set Computing (CISC) technology, and so on. When the control system 204 is in operation, the processor 310 can be configured to execute the software stored within the memory unit 306 to generally control and perform the one or more operations of the locomotive units 106, 108, 110 and the HVDC bus 202 pursuant to the software instructions.

[0054] In one example implementation, the central control system 204 may implement an energy management system configured to control the various operational modes of the locomotive units 106 and 108 to maximize fuel savings based on service demand, environmental conditions, historical data, train’s trip information, shore power locations, and the like. As shown in FIG. 3, the control system 1204 includes a database 312, which can be stored locally as part of the memory unit 306 or may be remote or cloud database. The database 312 may store various information and data associated with operating the locomotive consist 102. Such data is utilized or analyzed the control system 204 in real time to make automated decisions for power management, speed controls, emergency responses, and so on. For example, the database 312 may store sensor data 314, power consumption data 316, HVDC bus data 318, emissions data 320, and fuel consumption data 322. The sensor data 314 may include monitored or sensed parameters (real-time and historical) associated with the locomotive units 106, 108, 110. Some examples of sensors used within the locomotive units 106, 108, 110 may include, but not limited to, fuel level CPST Doc: 1388-1940-7389.1sensors, current and voltage sensors, temperature sensors, pressure sensors, and so on. These sensors provide operational data associated with the locomotive units 106, 108, 110 and this data is stored as sensor data 314 in the database 312.

[0055] The power consumption data 316 may include data associated with each of the locomotive units 106, 108, 110 indicative of power consumption measurements associated with various components that consume electric power within the locomotive units 106, 108, 110. For example, the power consumption data 316 may include traction power consumption data for each of the traction motors 122-1, 122-2, 122-3, auxiliary power consumption data for the auxiliary systems within each locomotive units 106, 108, 110, regenerative braking energy indicative of the amount of energy recovered through regenerative braking, total energy consumption by each and across all the locomotive units 106, 108, 110 within the locomotive consist 102. The power consumption data 316 may also include voltage and current profiles of each component that consumes electrical power within the locomotive consist 102.

[0056] The HVDC bus data 318 may include real-time and historical data associated with voltage levels, current flow, power quality, and temperatures monitored on the HVDC bus 202 that enable controlling operations of the HVDC bus 202 by the control system 204. The emissions data 320 may include measurements and records of pollutants, such as greenhouse gas emissions, released into the environment as a result of the locomotive’s operations. Similarly, the fuel consumption data 322 includes quantitative information on the amount of fuel consumed during operation of the locomotive consist 102.

[0057] Referring back to FIG. 2, in an example implementation, the central control system 204 may implement an energy management system configured to integrate the operations of locomotive units 106, 108, and 110. The energy management system can be configured to monitor, in real-time or near real-time, one or more operational parameters associated with each of the locomotive units 106, 108, and 110 and control, in real-time, operations of these locomotive units and the HVDC bus 202 to selectively enable transmission of electrical power signal between the locomotive units 106, 108, 110. The energy management system may also be configured to maximize regenerative braking energy for recharging batteries.

[0058] In operation, the control system 204 may be configured to operate the first locomotive unit 106 and the second locomotive unit 108 in various operational modes to maximize fuel savings based on service demands, environmental conditions, historical data, trip information, shore power locations, and so on. Thus, based on the service demands, the control system 204 may be configured to continuously monitor, such as in real-time, one orCPST Doc: 1388-1940-7389.1more operational parameters associated with the first locomotive unit 106 and the second locomotive unit 108 to determine how to operate these locomotive units 106, 108 to maximize energy efficiency, fuel savings, and minimize emissions. The operational parameters may include one or more of power requirements based on train’s loads and gradient of the railway track, battery charge levels, fuel levels, regenerative braking energy levels, emission levels, and the like. For example, when the train 100 is running on high gradient tracks, both first locomotive unit 106 and the second locomotive unit 108 may operate independently to maximize the traction power needed to ascend such steep gradients. Similarly, when the emissions need to be minimized or when the train 100 is operating on low speeds, the BEL or second locomotive unit 108 may be used as the primary source of power and the DEL or first locomotive unit 106 may only supply power to charge the batteries of the BEL or second locomotive unit 108. In another example scenario, when the train 100 is stationary and there is no external charging infrastructure available, the DEL or first locomotive unit 106 may generate electrical power to recharge the batteries of the BEL or second locomotive consist 108.

[0059] Based on these operational modes of the locomotive units 106, 108, the control system 204 is configured to enable or disable the HVDC bus 202 for transmission of electric power signals between the locomotive units 106, 108.

[0060] In a first operational mode, the control system 204 may transmit control signals to the DEL control system 142 and the BEL control system 154 to operate the first locomotive unit 106 and the second locomotive unit 108 in a parallel mode, wherein each of these locomotive units 106 and 108 operates independently to use their respective power sources 120-1 and 120-2 to drive the respective traction motors 122-1, 122-2. In this example, the first locomotive unit 106 may be configured to independently generate approximately 4300 horsepower (HP) of tractive power and approximately 70 Megawatts-hour (MWh) of energy for storage, for example, in the energy storage unit 125. Similarly, the second locomotive unit 108 may be configured to independently generate approximately 4300HP of traction power with 8MWh of energy storage. Accordingly, in the first operational mode, the first locomotive unit 106 and the second locomotive unit 108 may operate together to collectively provide a total of upto approximately 8600HP of traction power for driving the train 100. The first operational mode may be implemented by the control system 204 when the train 100 needs maximum power to propel, for example, to ascent steep gradients of railway tracks. Since the locomotive units 106, 108 operate in parallel mode, there is no electrical power being transmitted between the locomotive units 106, 108, and thus, the control system 204 may signal the HVDC bus 202 to be disabled in the first operational mode.CPST Doc: 1388-1940-7389.1

[0061] In a second operational mode, the control system 204 may operate the first locomotive unit 106 and the second locomotive unit 108 in a series hybrid mode. In this operational mode, the first locomotive unit 106 is configured to concurrently power the traction motors 122-2 and charge the battery assembly in the power source 120-2 of the second locomotive unit 106. In this mode, the first locomotive unit 106 may not power its own traction motors 122-1 and instead allow the power generated by the power source 120- 1 to be transmitted to the second locomotive unit 108 for powering their traction motors 122- 2 and for charging their power source 120-2. The second operational mode may be implemented by the control system 204 when the train 100 is running on low speeds or in urban areas where emissions need to be minimized. In this implementation of the second operational mode, the control system 204 enables the HVDC bus 202 to electrically connect the first locomotive unit 106 and the second locomotive unit 108 and allow transmission of the electric power signals therebetween. To that end, the control system 204 may convert the power generated by the power source 120-1 of the first locomotive unit 106 to the high-voltage DC electric power signal, such as by using the LC filter 156 and the first power conversion unit 158, over the HVDC bus 202 to the second locomotive unit 108. At the second locomotive unit 108, the received high voltage power signal from the HVDC bus 202 is converted by the second power conversion unit 160 into a suitable form required for charging the battery assembly within the power source 120-2. The received high-voltage signal is also transmitted to the traction motors 122-2 of the second locomotive unit 106 via the DC / DC converter 144 which steps down the voltage to the suitable voltage required by the traction motors 122-2.

[0062] In another implementation of the second operational mode, the control system 204 may be configured to dedicate the power generated by the power source 120-1 of the first locomotive unit 106 for charging the battery assembly in the power source 120-2 of the second locomotive unit 108. In this implementation, the control system 204 enables the HVDC bus 202 to enable transmission of the electric power signals from the power source 120-1 to the power source 120-2 via the power conversion units 158 and 160 in a similar manner as described above. This operational mode may be implemented, for example, when the train 100 is stationary, coasting in service, or not in service and / or when there is no external shore charging facility available to recharge the battery assemblies of the BEL or second locomotive unit 108.

[0063] In a third operational mode, the control system 204 may be configured to maximize the regenerative braking energy for charging the batteries of the BEL or second locomotive unit 108. In this operational mode, the first locomotive unit 106 and the second locomotive unit 108 may operate in series hybrid mode and the traction motors 122-1 and CPST Doc: 1388-1940-7389.1122-2 may collectively generate regenerative electric power, for example, up to 5 Megawatts (MW) to recharge the batteries of the second locomotive unit 108. In this operational mode, the regenerative electric power generated by the traction motors 122-1 of the first locomotive unit 106 may be transmitted over the HVDC bus 202 to the battery assemblies in the power source 120-2 of the second locomotive unit 108. The electric signals from the traction motors 122-1 may also be transmitted via the power conversion units 158 and 160 to maintain the voltage levels and power quality of the signal transmitted over the HVDC bus 202 and to the battery assemblies of the second locomotive unit 108.

[0064] In a fourth operational mode, the control system 204 may be configured to signal the engine 121 of the first locomotive unit 106 to shut down, for example, to meet zero emission operation targets. In this operational mode, the train 100 is driven by the BEL or second locomotive unit 108. Further, in this operational mode, the control system 204 enables the HVDC bus 202 to allow the power source 120-2 of the second locomotive unit 108 to transmit electric power to the HVDC bus 202. The HVDC bus 202 can in turn power the DC / DC converter 137 on the first locomotive unit 106. For example, the DC / DC converter 137 may be configured to power the auxiliary systems 136 on the first locomotive unit 106.

[0065] In a fifth operational mode, the control system 204 may disable the HVDC bus 204 and allow the battery assemblies in the power source 120-2 of the second locomotive unit 108 to be recharged using shore power from the external power grid 152 as described above.

[0066] In the following figures and description, the electric power transmission system 200 will be discussed as being implemented in locomotive consists 100 according to second and third embodiments. Similar elements in these embodiments are denoted by similar reference numbers, prefixed with a serial number representing the embodiment, such as '2' for the second embodiment, and '3' for the third embodiment, and so forth.

[0067] Referring to FIG. 4, an electric power transmission system 2200 implemented in a BEL or HL locomotive consist 2102 is illustrated. The locomotive consist 2102 includes a first locomotive unit 2106 and a second locomotive unit 2108, each embodied as a battery electric locomotive (BEL) unit and including its respective propulsion systems 2114 and 2116. In some examples, the locomotive consist 2102 of this embodiment may include a combination of BEL units and hybrid locomotive (HL) units, which can also be implemented in a similar manner. Similar to the BEL or second locomotive unit 108 described above, each of the first and second locomotive units 2106, 2108 include respective battery assemblies or power sources 2120-1 , 2120-2 configured to power the respective tractionCPST Doc: 1388-1940-7389.1motors 2122-1 and 2122-2 via respective DC / DC converters 2144-1, 2144-2. The first and second locomotive units 2106, 2108 further include respective braking systems 2146-1 and 2146-2 that implement regenerative braking energy systems that recycle the electric power generated by the traction motors 2122-1, 2122-2 to charge the respective battery assemblies 2120-1 and 2120-2. The first and second locomotive units 2106, 2108 also include respective axle generators 2148-1 , 2148-2 that contribute to powering auxiliary systems on the locomotive units 2106, 2108. In one example implementation, the battery assemblies in the power sources of all the locomotive units, i.e., the locomotive units 2106, 2108 in this example, are capable of being charged using a single shore power charge station 2152. Furthermore, each of the first locomotive unit 2106 and the second locomotive unit 2108 are controlled by their respective local control systems 2154-1 and 2154-2 that are embodied as EV control systems in a similar manner as described above for the BEL control system 154.

[0068] As shown, the first and second locomotive units 2106, 2108 are connected by MU cables 2112 and the HVDC bus 2202 configured to transmit control and communications signals and electric power signals, respectively, between the first locomotive unit 2106 and the second locomotive unit 2108. In an example implementation, a single HVDC bus 2202 may be configured to support up to three BEL locomotive units within the consist. However, in cases where there are more than three BEL locomotive units within the consist, more than one HVDC buses may be used to connect them in a similar manner as described here. The communication signals are transmitted over the MU cables 2112 using, for example, the LONWORKS® protocol.

[0069] A central control system 2204 may be configured to be operatively connected to the first locomotive unit 2106, the second locomotive unit 2108, the MU cables 2112 and the HVDC bus 2202. The control system 2204 may also implement an energy management system that may be configured to integrate the operations of the locomotive units 2106 and 2108 and the HVDC bus 2202 to maximize battery utilization and charging based on service demands, environmental conditions, historical data, trip information, shore power locations, and the like. To this end, the central control system 2204 may be configured to monitor the one or more operational parameters associated with the first and second locomotive units 2106, 2108 and control the operations of the units 2106, 2108 and the HVDC bus 2202 based on such operational parameters. In this embodiment, the one or more operational parameters may include power requirements based on the load of the train or the locomotive consist 2102, battery levels, regenerative braking energy levels, and the like.

[0070] The control system 2204 may be configured to operate each of the first locomotive unit 2106 and the second locomotive unit 2108 independently and in parallelCPST Doc: 1388-1940-7389.1mode to maximize the traction power generated for propelling the train. For example, each locomotive unit 2106 and 2108 may generate up to approximately 4300HP of traction power and more than 30MWh of energy storage and accordingly, in this mode, the locomotive units 2106, 2108 may collectively generate approximately 8600HP of traction power for propelling the locomotive consist 2102.

[0071] In a first operational mode, the control system 2204 may be configured to continuously monitor battery levels of each locomotive units 2106 and 2108 and configured to enable the HVDC bus 2202 to allow the locomotive units 2106 and 2108 to share power or charge the batteries of another locomotive unit, when the battery charge of any locomotive unit falls below a predefined threshold. To that end, the electric power signals from one power source, for example, power source 2120-1 , may be transmitted to charge the power source 2120-2 of the second locomotive unit 2108 via a first power conversion unit 2160-1 and a second power conversion unit 2160-2. For example, the first power conversion unit 2160 may include a DC / DC converter and / or a bidirectional AC / DC converter that may be configured to convert the electric power signal from the power source 2120-1 of the first locomotive unit 2106 into a suitable high voltage DC signal for transmission over the HVDC bus 2202. Similarly, the second power conversion unit 2160-2 can also include a DC / DC converter and / or bidirectional AC / DC converter that may be configured to regulate or adjust the voltage of the received electric power signal from the HVDC bus 2202 to a suitable voltage required for charging the batteries in the power source 2120-2 of the second locomotive unit 2108.

[0072] In a second operational mode, the control system 2204 may further be configured to enable sharing of regenerative braking power between the locomotive units 2106 and 2108 when the local battery has sufficient charge. To this end, the control system 2204 may be configured to monitor battery levels of each of the locomotive units 2106, 2108 and when battery charge level of one locomotive unit, say the first locomotive unit 2106, is greater than a first threshold and the battery charge of another locomotive unit, say the second locomotive unit 2108, falls below a second threshold, then the control system 204 may enable the HVDC bus 2202 to allow regenerative braking energy to flow from the first locomotive unit 2106 to the second locomotive unit 2108.

[0073] In an example implementation, in a third operational mode, the control system 2204 may be configured to enable shore power charging of all the locomotive units 2106, 2108 by using a single shore power charging facility 2152. To that end, the control system 2204 may be configured to enable the HVDC bus 2202 to enable transmission of electric power signal from the shore charging facility 2152 across the connected locomotive unitsCPST Doc: 1388-1940-7389.12106 and 2108. When the onboard charging port 2150 of the first locomotive unit 2106 is connected to the external shore power charging facility 2152, the power signal from the shore charging facility 2152 is first converted into low voltage signal by the DC / DC converter 2144-1 provided on the first locomotive unit 2106. This low voltage power is then provided to recharge the battery assembly in the power source 2120-1 of the first locomotive unit 2106. The low voltage signal also transmitted to the first power conversion unit 2160-1 which can convert the signal to the high voltage DC signal to be transmitted over the HVDC bus 2202 and to the second locomotive unit 2208. At the receiving end, the second power conversion unit 2160-2 of the second locomotive unit 2108 converts the high voltage DC signal from the HVDC bus 2202 to a lower voltage signal suitable for recharging the battery assembly in the power source 2120-2 of the second locomotive unit 2108. This process can also continue to a third locomotive unit that may be provided after the second locomotive unit 2108 in the consist 2102 in a similar manner.

[0074] Referring now to FIG. 5, an electric power transmission system 3200 implemented in a DEL locomotive consist 3102 is illustrated. The locomotive consist 3102 includes a first locomotive unit 3106 and a second locomotive unit 3108 that are each implemented as a diesel electric locomotive (DEL) unit. The components shown for each of the first locomotive unit 3106 and the second locomotive unit 3108 are the same as those of the first or DEL locomotive unit 106 shown and described in FIG. 2 and thus these components are not discussed in greater detail here. In this figure, besides being prefixed with the serial number “3” representing the embodiment of the electric power transmission system, the identical components of the DEL locomotive units are also suffixed with numbers “1” and “2” corresponding to the first diesel electric locomotive unit 3106 and the second diesel electric locomotive 3108, respectively.

[0075] In one example, the control system 3204 may incorporate the 1stDEL control system 3142-1 and the 2ndDEL control system 3142-2 into a single centralized control system embodied as the HHP control system configured to control the operations of each of the first and second locomotive units 3106, 3108 to maximize fuel efficiency and minimize emissions.

[0076] As shown, the first and second locomotive units 3106, 3108 are connected by MU cables 3112 and one or more HVDC bus 3202 configured to transmit control and communications signals and electric power signals, respectively, between the first locomotive unit 3106 and the second locomotive unit 3108. In an example implementation, a single HVDC bus 3202 may be configured to electrically connect or support up to three DEL locomotive units within the consist 3102. However, in cases where there are more thanCPST Doc: 1388-1940-7389.1three DEL locomotive units within the consist, more than one HVDC buses may be used to connect them in a similar manner as described here. The communication signals are transmitted over the MU cables 2112 using, for example, the LONWORKS® protocol.

[0077] The control system 3204 may be configured to monitor one or more operational parameters associated with the first and the second locomotive units 3106, 3108 and operate the HVDC bus 3202 and the locomotive units 3106, 3108 based on the same. To that end, in this example implementation, the operational parameters may include, but not limited to, fuel efficiency of the locomotive units 3106, 3108, electrical and power loads, fuel levels, emission levels and the like.

[0078] The control system 3204 may be configured to operate each of the first locomotive unit 3106 and the second locomotive unit 3108 independently and in parallel mode to maximize the traction power generated for propelling the train. For example, each locomotive unit 3106 and 3108 may generate up to approximately 4300HP of traction power and more than 70MWh of energy storage and accordingly, in this mode, the locomotive units 3106, 3108 may collectively generate approximately 8600HP of traction power for propelling the locomotive consist 3102. In implementations where there are three DEL locomotive units within the consist 3102, the total traction power generated by the locomotive consist 3102 may be approximately up to 12900HP. In this mode, the control system 3204 may be configured to disable the HVDC bus 3202 to electrically disconnect the locomotive units 3106, 3108 from one another.

[0079] In an example implementation, the control system 3204 may be configured to operate the locomotive consist 3102 in a power sharing operational mode. In this mode, the control system 3204 may be configured to enable the HVDC bus 3202 to electrically couple the locomotive units 3106, 3108 and allow power sharing between them. For example, to reduce emissions or in case of engine failure, the control system 3204 may be configured to shut down a power source, say the power source 3120-1 of one of the locomotive units, i.e, the first locomotive unit 3106, and allow the power source of the other locomotive units, such as the power source 3120-2 of the second locomotive unit 3108 to power the traction motors 3122-1 of the first locomotive unit 3106 along with its own traction motors 3122-2. In this case, the control system 3204 may enable the HVDC bus 3202 to enable the power source 3120-2 to transmit electric power signals over the HVDC bus 3202 to the traction motors 3122-1 of the first locomotive unit 3108. At the transmission side, the second locomotive unit 3108 may include first power conversion unit 3158-2 and LC filter 3156-2 configured to regulate one or more power transmission parameters of the signal before transmitting the same on to the HVDC bus 3202. The LC filter 3156-2 may filter the unwanted frequenciesCPST Doc: 1388-1940-7389.1from the AC power signal from the power source 3120-2 and the power conversion unit 3158-2 may convert the AC signal into high-voltage DC signal suitable for transmission on the HVDC bus 3202. Similarly, the power conversion unit 3158-1 and the LC filter 3156-1 on the first locomotive unit 3106 may be configured to regulate the electric power signal before transmitting the same over the HVDC bus 3202 in cases where the power source 3120-2 is shut down and the power source 3120-1 is configured to power the traction motors 3122-2 of the second locomotive unit 3108. At the receiving end, the high voltage DC power signal received from the HVDC bus 3202 is converted to suitable form by the respective power conversion unit, i.e., the power conversion unit 3158-1 in this example, for powering the respective traction motors, such as the traction motors 3122-1.

[0080] Further, the control system 3204 may be configured to power the APUs 3138-1, 3138-2, which are also implemented as Hotstart type APUs in an example, when either of their respective engines are shut down. For example, in case the engine 3121-2 of the second locomotive unit 3108 fails, the control system 3204 may be configured to enable the HVDC bus 3202 to power the APU 3138-2 to maintain temperatures of the engine coolant and oil on the second locomotive unit 3108. In this example, the control system 3204 may be configured to control the HVDC bus 3202 to draw or receive power from the power source 3120-1 of the first locomotive unit 3106 to in turn power the APU 3138-2 of the second locomotive unit 3108 via the power conversion units 3158-1 and 3158-2 in a similar manner as described above.

[0081] For simplicity and clarity of illustration, where considered appropriate, reference numerals can be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the examples described herein. However, it will be understood by those of ordinary skill in the art that the examples described herein can be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the examples described herein. Also, the description is not to be considered as limiting the scope of the examples described herein.

[0082] It will be appreciated that the examples and corresponding diagrams used herein are for illustrative purposes only. Different configurations and terminology can be used without departing from the principles expressed herein. For instance, components and modules can be added, deleted, modified, or arranged with differing connections without departing from these principles.

[0083] It will also be appreciated that any module or component exemplified herein that executes instructions can include or otherwise have access to computer readable mediaCPST Doc: 1388-1940-7389.1such as storage media, cloud storage, computer storage media, or data storage devices (removable and / or non-removable) such as, for example, magnetic disks, optical disks, or tape. Computer storage media can include volatile and non-volatile, removable and nonremovable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data.Examples of computer storage media include RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by an application, module, or both.

[0084] The steps or operations in the flow charts and diagrams described herein are just for example. There can be many variations to these steps or operations without departing from the principles discussed above. For instance, the steps can be performed in a differing order, or steps can be added, deleted, or modified.

[0085] Although the above principles have been described with reference to certain specific examples, various modifications thereof will be apparent to those skilled in the art as outlined in the appended claims.CPST Doc: 1388-1940-7389.1

Claims

CLAIMS:

1. An electric power transmission system for a locomotive consist comprising a first locomotive unit and a second locomotive unit, the electric power transmission system comprising:a direct current electrical bus connected to each of the first locomotive unit and the second locomotive unit and configured to selectively enable transmission of electric power signals between the first locomotive unit and the second locomotive unit; anda control system operatively connected to the direct current electrical bus, the first locomotive unit and the second locomotive unit, control system being configured to:monitor one or more operational parameters associated with the first locomotive unit and the second locomotive unit; andcontrol operations of the direct current electrical bus based on the operational parameters.

2. The electric power transmission system of claim 1 , wherein the direct current electrical bus is a multi-unit high-voltage direct current (HVDC) bus.

3. The electric power transmission system of claim 2, wherein the high-voltage direct current (HVDC) bus is adapted to enable transmission of electric power signals at high voltages within a range of 200 volts direct current to 3000 volts direct current.

4. The electric power transmission system of claim 1 , wherein the one or more operational parameters include one or more of power requirements based on an electrical load of the locomotive consist, battery charge level, fuel level, regenerative braking energy level, and emission levels.

5. The electric power transmission system of claim 1 , wherein the first locomotive unit is a diesel electric locomotive comprising a diesel power source configured to power first traction motors of the first locomotive unit, and the second locomotive unit is one of a battery electric locomotive or a hybrid locomotive comprising a battery assembly configured to power second traction motors of the second locomotive unit.

6. The electric power transmission system of claim 5, wherein in a first operational mode, the control system is configured to operate the first locomotive unit and the second locomotive unit independently to enable powering of the first and second traction motors by the diesel power source and the battery assembly, respectively, and wherein the control CPST Doc: 1388-1940-7389.1system is configured to disable the direct current electrical bus to electrically disconnect the first locomotive unit from the second locomotive unit.

7. The electric power transmission system of claim 5, wherein in a second operational mode, the control system is configured to enable the direct current electrical bus to electrically connect the first and second locomotive units for transmitting electric power signal from the diesel power source of the first locomotive unit to one or more of the second traction motors and the battery assembly of the second locomotive unit.

8. The electric power transmission system of claim 5, wherein the control system is configured to enable the direct current electrical bus for transmitting electric power signal from the battery assembly of the second locomotive unit to one or more auxiliary power generation components of the first locomotive unit, the auxiliary power generation components being configured to power one or more auxiliary systems on the first locomotive unit.

9. The electric power transmission system of claim 1 comprising a regenerative braking energy system configured to enable generation of regenerative electric power during braking of one or more of the first and second locomotive units, and wherein the control system is configured to enable transmission of the generated regenerative electric power over the direct current electrical bus from one of the first locomotive unit and the second locomotive unit to the other one of the first locomotive unit and the second locomotive unit.

10. The electric power transmission system of claim 1 further comprising at least one first power conversion unit provided on the first locomotive unit and at least one second power conversion unit provided on the second locomotive unit, wherein each of the first power conversion unit and the second power conversion unit is configured to control one or more power transmission parameters of the electric power signal for transmission to or from the direct current electrical bus.

11. The electric power transmission system of claim 10, wherein each of the first power conversion unit and the second power conversion unit includes one or more of a bidirectional alternating current (AC) - direct current (DC) converter, a direct current (DC) - direct current (DC converter, and a voltage conversion unit configured to adjust voltage levels of the electric power signal.CPST Doc: 1388-1940-7389.

112. The electric power transmission system of claim 1 , wherein each of the first locomotive unit and the second locomotive unit includes one of a battery electric locomotive unit and a hybrid locomotive unit, and includes a battery assembly configured to power respective traction motors of the first and second locomotive unit.

13. The electric power transmission system of claim 12, wherein the control system is configured to enable the direct current electrical bus for transmission of electric power signal from a power source of one of the first and second locomotive units to one or more auxiliary power generation components of the other one of the first and second locomotive units.

14. The electric power transmission system of claim 12, wherein the control system is configured to:enable the direct current electrical bus for transmission of electric power signals from the battery assembly of one of the first locomotive unit and the second locomotive unit to recharge the battery assembly of the other one of the first locomotive unit and the second locomotive unit.

15. The electric power transmission system of claim 12, wherein the control system is configured to enable the direct current electrical bus to electrically connect the first locomotive unit and the second locomotive for receiving electric power signal from a single external charging facility connected to one of the first and second locomotive unit and recharging the battery assemblies of both of the first and second locomotive units.

16. The electric power transmission system of claim 1 , wherein each of the first locomotive unit and the second locomotive unit is a diesel electric locomotive unit and includes a diesel power source configured to power respective traction motors of the first and second locomotive units.

17. The electric power transmission system of claim 16, wherein the control system is configured to enable the direct current electrical bus for transmission of electric power signals from the diesel power source of one of the first and second locomotive units to traction motors of the other one of the first and the second locomotive units.

18. The electric power transmission system of claim 16, wherein the control system is configured to enable the direct current electrical bus for transmission of electric power signal from the diesel power source of one of the first and second locomotive units to one or moreCPST Doc: 1388-1940-7389.1auxiliary power generation components of the other one of the first and second locomotive units.

19. A locomotive consist for a train, the locomotive consist comprising:a first locomotive unit;a second locomotive unit connected to the first locomotive unit for propelling the train on a railway track;one or more communication cables connected to each of the first and second locomotive units, the one or more communications cable being configured to enable transmission of communication and control signals between the first and second locomotive units;a direct current electrical bus connected to each of the first and second locomotive unit, the direct current electrical bus being configured to selectively enable transmission of electric power signals between the first and second locomotive units; anda control system operatively connected to the first locomotive unit, the second locomotive units, the one or more communications cables, and the direct current electrical bus, the control system being configured to:monitor one or more operational parameters associated with the first locomotive unit and the second locomotive unit; andcontrol operations of the direct current electrical bus based on the monitored operational parameters.

20. The locomotive consist of claim 18, wherein the direct current electrical bus is a multi-unit high-voltage direct current (HVDC) bus adapted to enable transmission of electric power signals at high voltages within a range of 200 volts direct current to 3000 volts direct current.

21. The locomotive consist of claim 18, wherein the one or more operational parameters include one or more of power requirements based on an electrical load of the locomotive consist, battery charge level, fuel level, regenerative braking energy level, and emission levels.CPST Doc: 1388-1940-7389.1

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