Technical field

[0001] The present invention relates generally to drive systems and operation thereof for trains and more particularly to a supplementary drive system with a master control system and traction bogies which increases the capability of rail operation.

Background art

[0002] Freight Rail Companies operate their assets at maximum capability in terms of both assets' capacity and external restrictions. To grow and increase the business return-on-investments, organizations need to either invest in more rolling stock, such as more locomotives and freight cars and/or increased traffic or resolve capacity restrictions on existing systems. The most effective solution would permit both cost-effective and environment friendly added traction capacity as well as allowance for increased freight volumes, as well as optimized energy management.

[0003] In rail operation, there are a number of functional needs. One basic need is the capacity to pull freight wagons between two locations within given timetable slots or equivalent time/track constraints. This involves the need for enough acceleration and maximum speed to fulfil this basic need. Another requirement is enough and safe deceleration performance to comply to applicable local, regional or global regulations. The effective braking power and brake mass percentage decide mass limit for the freight train set.

[0004] Todays’ transportation systems solutions are designed and operate according to both above physical and regulatory constraints. This means that there are capability limitations on the existing train systems setting the limits on operational performance of the assets. The train operators maximize transportation capability by adding locomotives (expensive traction units) distributed in the freight train to handle traction and adhesion needed and balance the dynamic inter-train longitudinal forces (coupler forces) that emerge in operation.

[0005] Added extra traction units, i.e. , locomotives, are capital intensive and in addition introduce extra surplus to administration, organizational and other life cycle costs above its function as extra drive units. Furthermore, from a technical viewpoint, adding more locomotives does not directly solve the complex inter-train dynamics that sets restrictions on maximum specified standard speed and payload capacity.

[0006] As technology develops, opportunities emerge to replace the drive units (extra locomotives) with more efficient solutions.

[0007] US patent publication US 2010/028122 A1 discloses a quasi self- contained energy storage and power supply system that can be installed on carrying axles or bogies of railway cars. The disclosed system involves no central control. Instead, control is based on parameters sensed by each bogie, such as the acceleration felt by the bogie, its slope and speed as well as sensed pressure of the brake pipe.

[0008] European patent publication EP 3 277 535 B1 discloses a mechanical regenerative railway braking system, wherein a transmission system is selectively operable between different modes in dependence of control signals from a prime mover.

Summary of invention

[0009] An object of the present invention is therefore to provide for an efficient solution to increase the capability of rail operation within the constraints of today’s restrictions.

[0010] The invention is based on the insight that a master control system that monitors system status, movement, geographical position and mission profile metrics and that acts accordingly will provide a system with increased capability of rail operation. [0011 ] According to a first aspect of the invention, a supplementary drive system for a train is provided comprising a locomotive and at least one wagon mechanically connected to the locomotive, wherein the supplementary drive system comprises: at least one wagon unit adapted to be arranged in said at least one wagon, the wagon unit comprising: an electrical energy storage, and a drive unit electrically connected to the energy storage and comprising a motor/generator mechanically coupled to a drive axle of the wagon, wherein the drive unit during operation provides for a generative transmission of power between the drive axle and the energy storage, the supplementary drive system being characterized by a master control unit, preferably adapted to be arranged in the locomotive, comprising a master processing unit comprising means for storing a database and processing means, a communication link connected to the master processing unit and enabling transmission of data between the master processing unit and the at least one wagon unit, the supplementary drive system further comprising sensors comprising a locating device adapted to determine the geographical position of the master unit.

[0012] In a preferred embodiment, the locating device comprises a Global Navigation Satellite System (GNSS), preferably with a GPS device.

[0013] In a preferred embodiment, a plurality of wagon units (30) is provided.

[0014] In a preferred embodiment, a wagon unit is provided in all wagons, in every second wagon, or in a middle and a last wagon of said at least one wagon.

[0015] In a preferred embodiment, the master control unit is adapted to be set to one of the following states: turned on, off, and automatic.

[0016] In a preferred embodiment, the master control unit is adapted to, during running of the train, monitor information relating to the train, preferably system status, movement, geographical position and mission profile metrics and to act accordingly. [0017] In a preferred embodiment, the master control unit is adapted to, during running of the train, detect what a train driver wants to do and to give individual wagon units orders what to do based on system logic.

[0018] In a preferred embodiment, the master control unit is adapted to, during running of the train, monitor status of the track system in terms of wear or the status of the railway embankment.

[0019] In a preferred embodiment, the bogie control unit comprises a bogie communication unit adapted to communicate, preferably wirelessly, with other units, such as other bogie control units and the master control unit.

[0020] In a preferred embodiment, a bogie control unit is provided in each wagon unit, the bogie control unit being connected to at least one sensor.

[0021 ] In a preferred embodiment, the at least one sensor comprises any of the following: a speed sensor, preferably connected to the axles, an accelerometer, a gyroscope, a vibration sensor, and a sound sensor.

[0022] In a preferred embodiment, the wagon unit comprises a locating device, preferably a Global Navigation Satellite System with a GPS device.

[0023] According to a second aspect of the invention, a train is provided comprising a supplementary drive system according to the first aspect of the invention.

[0024] According to a third aspect of the invention, method of operating a supplementary drive system according to the first aspect of the invention is provided, the method comprising the steps of: identifying the train, preferably by entering train identification, downloading train route data, preferably comprising topography data, to the master control unit, optionally confirming the train rout data by the master control unit and a driver, sensing position of the master control unit and the at least one wagon unit, and controlling the at least one wagon unit based on the data of train route and the position of the at least one wagon unit. [0025] In a preferred embodiment, the method comprises, if cargo is loaded and data is deviating from pre-programmed, putting in metrics for the deviation, preferably number of wagons, weight and weight distribution of the train set/wagons, and calculating optimal drive and charge operation over the route based on track profile, batteries charge status, cargo load and detected position.

[0026] In a preferred embodiment, the method comprises continuously updating train route data, preferably based on charge level of energy storage(s).

[0027] In a preferred embodiment, the at least one wagon control unit controls the generative transmission of energy between the energy storage and the drive unit under control from the master control unit.

[0028] In a preferred embodiment, the step of controlling the at least one wagon unit comprises the wagon unit adding traction, brake force or be put in neutral mode to compensate for local longitudinal forces or optimize the train drive energy effectiveness over the route.

[0029] In a preferred embodiment, the method comprises sensing the acceleration of the master control unit and the at least one wagon unit, and controlling the supplementary drive system in dependence on a difference between acceleration of the master control unit and the at least one wagon unit.

[0030] In a preferred embodiment, the method comprises comparing differences between longitudinal acceleration of different wagon units to detect oscillating longitudinal forces and controlling the supplementary drive system to counteract the oscillating forces.

[0031] In a preferred embodiment, the method comprises continuously collecting route data from the sensor(s) for a specific route.

[0032] In a preferred embodiment, the method comprises forming historical data of continuously collected route data. [0033] In a preferred embodiment, the method comprises providing traction by means of the at least one wagon unit if the train enters a non-electrified part of a track.

[0034] In a preferred embodiment, train operation can be in any of the following modes: Acceleration, Cruising, Deceleration, Ascending or Undulating track operation, and Descending.

[0035] In a preferred embodiment, the supplementary drive system determines optimal charge and drive operation/procedure in order to fulfil the mission using at least some of train/system configuration, payload data, system status, route data (topology, speed limits etc.), timetable, GPS position and speed.

[0036] According to a fourth aspect of the invention, a method of creating train route data for a specific train for use in the method according to the second aspect of the invention, method of creating train route data comprising an iterative process of: defining line sections, calculating operating parameters for a first line section of the line sections, calculating operating parameters for a second line section of the line sections, and iteratively adding third and further line sections, thereby creating train route data for a specific train.

[0037] In a preferred embodiment, the method of creating train route data for a specific train comprises defining a line as a definable section of railway track with properties chosen from the following: line speed, track gradient profile, and a bool defining whether regenerative operation of wagon units is allowed while locomotive applies traction.

[0038] In a preferred embodiment of the method of creating train route data for a specific train, a simulation is based on simulation of a system of coupled equations, where each individual equation describes the movement of a single vehicle of a train.

[0039] In a preferred embodiment of the method of creating train route data for a specific train, the simulation process is an iterative process, iteratively finding correct braking points and joining simulations. [0040] In a preferred embodiment, the method of creating train route data for a specific train comprises defining each vehicle in the train by properties chosen from the following: vehicle ID, type, i.e. , locomotive or wagon, traction wagon or conventional wagon, static mass, relative mass addition, adhesive mass for acceleration, adhesive mass for braking, number of axles on vehicle, vehicle length, rated power, maximum tractive effort, brake type, power consumption, energy storage limit, initial energy stored, regeneration efficiency, and drive system efficiency.

[0041 ] In a preferred embodiment of the method of creating train route data for a specific train, optimal charge and drive operation is calculated in order to maximize the effectiveness of the supplementary drive system over the planned route using at least some of the following parameters as input parameters: charge status of energy storages, load route data, such as topology and speed limits, and position of the supplementary drive system.

[0042] According to a fifth aspect of the invention, a method of identifying maintenance need of a rail section is provided, comprising the following steps: comparing current route data with historical data for a specific route, and identifying rail maintenance needs, based on abnormalities between current route data and/or historical route data

[0043] According to a sixth aspect of the invention, a method of identifying maintenance need of a train is provided, comprising the following steps: comparing current wagon data, preferably acceleration data, with historical data for a specific wagon, and identifying wagon maintenance needs, based on abnormalities between current wagon data and historical wagon data.

[0044] According to a seventh aspect of the invention, a wagon unit for a supplementary drive system for a train according to the first aspect of the invention is provided, the wagon unit comprising: an electrical energy storage, and a drive unit electrically connected to the energy storage and comprising a motor/generator mechanically coupled to a drive axle of the wagon, wherein the drive unit during operation provides for a generative transmission of power between the drive axle and the energy storage, the wagon unit being characterized by a bogie communication unit adapted to communicate, preferably wirelessly, with other units, such as other bogie control units and the master control unit.

[0045] In a preferred embodiment, the wagon unit comprises sensors comprising a locating device adapted to determine the geographical position.

Brief description of drawings

[0046] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is an overall view of a prior art traditional train;

Fig. 2 is an overall view of a train modified with a system according to the present invention;

Fig. 3 is a view of a traditional bogie modified in accordance with the invention;

Fig. 4 is an overall diagram showing the different components of a system according to the invention;

Fig. 5 shows a wagon remotely controlled by means of a mobile control unit;

Fig. 6 is a diagram showing a graphical example of what a speed profile could look like;

Fig. 7 is a diagram corresponding to Fig. 6 but visualizing a simulated train speed;

Fig. 8 is a diagram showing how the calculation of tractive force is done in simulation;

Fig. 9 illustrates coupling forces between different vehicles;

Fig. 10 shows the accumulated energy as function of time for each vehicle; and

Fig. 11 is a presentation of a vehicle speed and height in relation to a starting point. Description of embodiments

[0047] In the following, a detailed description of a supplementary drive system for a train according to the invention will be described.

Definitions

[0048] The following definitions will be used in this description:

[0049] Traction bogie: A traction bogie is a bogie equipped with traction motors/generators and local energy storage for energy supply to the traction motors. The traction motors will only be able to operate if there is energy available in the local energy storage unit.

[0050] Locomotive: A locomotive is in this description a vehicle fitted with traction motors, preferably electric traction motors, and which is able to apply traction independent of the energy supply. A locomotive can never run out of energy for traction. . The term locomotive should be interpreted to include an Electrical Multiple Unit (EMU) or a Diesel Multiple Unit (DMU).

[0051 ] Vehicle: A vehicle is in this context defined as a unit with wheels coupled in a train and can be a locomotive or a wagon, and the wagon can in turn be a normal wagon or a wagon with traction bogies.

[0052] Traction vehicle: A locomotive or a wagon fitted with traction bogies.

[0053] Bogie: A bogie is a carriage located under a vehicle, on which axles provided with wheels are attached. It is movable from the frame of the vehicle and intended to be directed suitably in curves.

[0054] Line: A line is a definable section of railway track, where the properties that can be defined in this context can be, but is not limited, to:

Speed profile (see below).

Gradient profile (see below)

Adhesion as function of speed (see definition of adhesion below). [0055] Speed profile: A speed profile is defined as function of speed for a line section, and it sets the speed for which the train will strive to run at. The speed profile has the look of a “stepwise” function, where the maximum permitted speed is changed as steps at specific positions.

[0056] Gradient profile: A gradient profile is, just as the speed profile, defined stepwise as function of speed. It defines the vertical gradient (upward and downward slope) for the line and impacts the running resistance acting on the train.

[0057] Adhesion: The friction between the wheel and rail is what allows for the horizontal forces to be transmitted between wheel and rail.

[0058] Relative mass addition: The large masses of the rotational parts of a train also possess energy. This energy must be supplied during traction and dissipated during braking and shall due to their relatively large contribution be part of calculations.

[0059] Inter-train longitudinal forces: Dynamic forces between wagons due to inertia which could lead to coupler fractures or other mechanical failures as well as derailment if not handled properly.

Overall description

[0060] Reference is now made to Fig. 1 , wherein a prior art train, generally designated 1 , is shown. The train is made up of a one or more locomotives 10, in the shown example two locomotives, and a plurality of wagons 20’, in the shown example four wagons, running on rails 40. These vehicles are interconnected in series by means of couplers and each vehicle comprises a pair of conventional bogies 30’, one bogie in each end of the vehicle.

[0061] The locomotives 10 provide a traction force advancing the train on the rails while the wagons 20’ connected to the locomotives are advanced together with the locomotives. Thus, the wagons do not provide any traction force themselves. [0062] In Fig. 2, a train with a supplementary drive system according to the invention is shown. This train is also made up of at least one locomotive and a plurality of wagons. However, a fundamental difference from the conventional prior art train shown in Fig. 1 is that at least one wagon is a traction wagon 20 and in the figure all wagons are traction wagons. Thanks to the traction provided by the traction wagons, the composition of the train can be made more efficient. Thus, in this example, instead of having two locomotives 10 and four wagons 20’, the train according to the invention comprises a single locomotive 10 and seven traction wagons 20. Fig. 2 is of course just an example, but it gives an indication of the impact of the use of traction wagons as compared to conventional trains with no traction wagons.

Traction bogie

[0063] A bogie 30 of a traction wagon will now be described with reference to Fig. 3. The bogie 30 comprises a frame 32, on which two drive axles 34 are rotatably attached, preferably by means of bearings (not shown). Each axle 34 is provided at the outer ends thereof with a pair of wheels 35, which run on the rails 30. An electrical energy storage 36 is provided for storing and releasing electrical energy, as will be explained below. A drive unit 38 is electrically connected to the energy storage 36 and comprises motor/generator 38a mechanically coupled to an axle of the wagon, wherein the drive unit during operation provides for a generative transmission of power between the drive axles 34 and the energy storage 36. The drive unit 38 also comprises an energy converter 38b adapted to control the transfer of energy between the energy storage 36 and the motor/generator 38a. Additional parts comprised in the bogie 30 will be described below with reference to Fig. 4.

[0064] Each of the vehicles in a train according to the invention is defined by properties, including but not limited, to the following: vehicle ID, type, i.e. , locomotive or wagon, traction wagon or conventional wagon, static mass, relative mass addition, adhesive mass for acceleration, adhesive mass for braking, number of axles on vehicle, vehicle length, rated power, maximum tractive effort, brake type, power consumption, energy storage limit, initial energy stored, regeneration efficiency, and drive system efficiency.

[0065] These properties will be explained in more detail below.

[0066] A system comprising a traction bogie 30 of a traction wagon 20 and a master unit 50, which preferably is provided in the locomotive 10, will now be described with reference to Fig. 4. As explained above, the bogie 30 is provided with axles 34 driven by a motor/generator 38a powered by an energy storage 36. A bogie control unit 39 of the bogie 30 is connected to a number of sensors, such as speed sensors 34a, preferably connected to the axles 34, and an accelerometer 39a sensing the acceleration or deceleration of the bogie 30. Optionally, a gyroscope (not shown) is connected to the bogie control unit 39, being comprised in an inertial navigation system. In order to determine the geographical location of the traction bogie 30, a locating device 39b is provided. This locating device may be a Global Navigation Satellite System (GNSS) with a GPS device 39b acting as the locating device. The bogie control unit 39 is adapted to communicate, preferably wirelessly, with other units via a bogie communication unit 39c.

[0067] Optionally, a traction bogie 30 may be provided with vibration and/or sound sensors. By means of these vibration and sound sensors, data relating to deviations from normal may be recorded and identified. This data constitutes “fingerprints” indicating faults or conditions leading to faults. By storing these “fingerprints” in the traction bogies 30 and connect each “fingerprint” to a fault condition, these fault conditions can be identified by a traction bogie 30, also in a traction bogie where the fault in question has not occurred.

[0068] “Fingerprints” identified as connected to fault conditions may be stored in a general database to be used globally by all traction bogies 30.

Master control unit

[0069] A master control unit 50 comprises a master processing unit 52 for processing and storing data, handling algorithms etc., as will be described below. A master communication unit 54 is connected to the master processing unit 52 and adapted for communication with bogie control units 39 via a communication link, preferably a wireless communication link, such as a radio link, which preferably is secure. A control interface 56 is also connected to the master processing unit 52 and adapted for interaction with an operator, such as a train driver. The control interface may comprise a screen and an input device, such as a keyboard and mouse or similar devices.

[0070] The master control unit 50 is adapted to monitor information relating to the train 1 , such as system status, movement, geographical position and mission profile metrics (i.e. , awareness) and acts accordingly. It also detects what the train driver wants to do and gives the individual traction bogies 30 orders what to do based on system logic. For instance, if the train driver wants to accelerate, the master control unit 50 detects it, and based on system logic orders the traction system comprising the traction bogies 30 to assist the locomotive in acceleration. The amount of effort each or all traction bogies 30 in the train system should use can be individually preprogrammed or decided instantly based on track route, system status and geographical location.

[0071] The communication link between the master control unit 50 and the traction bogies 30 is a primary functional capability of the supplementary drive system. The network communication and processing of data must be fast enough to allow for individual modules drive and charge actions for the traction bogies 30 to have intended effect on inter-train longitudinal forces. The communication link must also be designed to perform its function unobstructed in proximity of the railway high-voltage line following line EMC demands.

[0072] Fig. 5 shows a wagon remotely controlled by means of a mobile control unit. This means that the operation of individual wagons is possible, without them being connected to a locomotive, as long as the energy storage is not depleted.

Operation

[0073] If the train driver wants to brake or decelerate, the master control system detects that as well and orders the traction bogies 30 to use the generator function of the respective motor/generator 38a and charge the energy storages 36 in the form of on-board electrical storage, such as batteries and/or capacitors and thus assist in braking the train 1 . Should on-board batteries already be fully charged, a brake resistor (not shown in the figures) will be needed if the motors/generators 38a are of synchronous type or if the motors/generators 38a are asynchronous, the charging function will be switched off.

[0074] At all times during coasting, the system acts upon wagon local longitudinal forces that adds and subtracts during operation. This function allows for higher maximum speed and gives the stakeholders strategic benefits for both the operators and infrastructure owner. Furthermore, benefits also include reducing coupler forces and risks for derailing as well as prolonging service life of couplers. [0075] The system can in parallel be used to monitor the status of the track system in terms of wear or the status of the railway embankment. This information may be used for future operations to avoid derailing etc.

[0076] In operations where individual shunting is needed, the shunting operation is already known when the train leaves its origin and part of that preprogramming could be individual instructions to cars on how to act when they reach a shunting yard. Any train 1 starting its journey uses a schedule, usually in the terms of an operation identification number or similar. The preprogramming of the system can be done related to the actual operation identification number. Before the journey starts, the instructions are downloaded to the master processing unit 52 and confirmed by the Master unit and the driver.

Scenarios

[0077] A non-limiting example of a train operation will now be given to illustrate the function of a supplementary drive system according to the invention.

[0078] A freight train will have the following mission: a) go to location A at date/time X to load cargo, b) at date/time Y depart for location B, c) at date/time Z unload cargo, d) when unloading is complete, return empty freight train and wagons to location C or return at once to location A for repeated mission.

Operations Scenarios

[0079] Upon mission start, the train driver starts the freight train and goes through check-list of train. Then the driver goes through check-list of the supplementary drive system in the control interface 56 in the cab of the locomotive 10. Dependent on system status the driver either sets supplementary drive system in automatic mode, manual mode or chooses not to use the supplementary drive system or makes required interventions and reports deviations in the control interface 56.

[0080] If the driver decides to use the supplementary drive system, the train # must be entered and then supplementary drive system downloads route data including track data and topology. If cargo is loaded and data is deviating from preprogrammed the driver also puts in metrics for this; number of wagons, weight and weight distribution of the train set/wagons. The supplementary drive system then calculates optimal drive and charge operation over the route based on track profile, batteries charge status, cargo load and detected position. This drive and charge schedule will be updated continuously based on batteries charge level.

[0081] In automatic drive mode the supplementary drive system operates autonomously based on route data as well as parameters loaded and collected continuously. Data from each traction bogie 30 are transferred via the link between the communication units 39c, 54 in the traction bogie 30 and the master control unit 50, respectively, and gathered in the master control unit 50. The supplementary drive system continuously processes the data from all sensors and parameters and decides instantaneously on actions for each traction bogie 30 to optimize train running efficiency. The traction bogies 30 will either add traction or brake force or be put in neutral mode to compensate for local longitudinal forces or optimize the train drive energy effectiveness over the route.

[0082] If the train 1 for any reason enters a non-electrified part of a track, the supplementary drive system is preferably pre-programmed to provide traction for this part of the operation. The driver needs to set this in the control interface 56 at the start of operation to give the supplementary drive system enough leverage to charge the batteries 36 enough to complete this mission.

Pre-Acquisition Business Case Simulation and System Configuration

[0083] In order to properly set up the supplementary drive system, data from customer operations and existing system are collected in order to simulate benefits and optimal customization of capabilities of the supplementary drive system.

[0084] Before the acquisition stage can begin a thorough analysis of the customer’s business is conducted where the fit of the supplementary drive system is evaluated. The results of this activity are the economical and effectiveness benefits as well as the required supplementary drive system technical configuration.

Startup and Mission Preparation

[0085] Before a mission is initiated, i.e. , before train operation, network communication is performed with all sub-systems of the whole supplementary drive system at purposive speed. This involves communication between the master control unit 50 and the traction bogies 30.

[0086] Then, optimal charge and drive operation is calculated in order to maximize the effectiveness of the supplementary drive system over the planned route. This calculation uses at least some of the following parameters as input parameters:

Load status of all batteries 36

Load Route Data (Topology, speed limits etc.)

Position of the supplementary drive system

Operation

[0087] Train operation can be in any of the following modes:

Acceleration

Cruising

Deceleration

Ascending or Undulating track operation

Descending [0088] In the acceleration mode, the locomotive 10 is accelerated to start providing traction and adhesion addition inside the envelope of the current optimal charge and drive program. Traction from traction modules added over whole train to compensate for inter-train longitudinal forces (coupler forces) in order to allow for reduction of locomotives and/or increase of freight volume.

[0089] In the cruising mode, inter-train longitudinal forces (coupler forces) are sensed and acted on if needed in order to achieve the calculated higher operating speed.

[0090] In this mode, batteries are charged if Optimal Charge and Drive Operation algorithm conditions breach lower limit for mission success in order to fulfil mission.

[0091] In the deceleration mode, batteries are charged.

[0092] In the ascending mode, traction is added from the flock of traction bogies 30 or batteries 36 are charged to compensate for Inter-Train Local Longitudinal Forces to maintain optimal speed and minimize coupler forces. To achieve this, the true speed and directional vectors are sensed over bode?? individual traction bogies 30 and the complete flock of traction bogies 30 in the train 1 to calculate balancing behavior. Extra traction is added if needed to allow for reduction of the number of locomotives and/or to increase freight volume.

[0093] The ascending mode is also applicable on undulating track section.

[0094] In the descending mode, batteries are charged. Braking force is applied by the traction bogies 30 to compensate for Inter-Train Local Longitudinal Forces to optimize speed and minimize coupler forces in order to allow for increased freight volume.

[0095] By applying these modes of operation to a train 1 provided with one or more traction bogies 30, costly alternatives, such as running with extra pulling locomotives or reducing the freight volume, are avoided.

Support [0096] Upon startup of the supplementary drive system, a condition monitoring function executes a full system check and gives the user a summary in the control interface 56 of the status of each traction bogie 30 as well as the status (capacity) of the complete supplementary drive system. This will be input to control/mission algorithms as well as to the remedy actions the driver needs to perform in order to get the system ready for mission. Data from the checkup/test will be sent to the support organization and if corrective/support interventions are needed this will be communicated and handled accordingly.

[0097] During operation the supplementary drive system sends condition data relating to health and performance etc. to a support organization for maintenance and support decision making. Should a critical failure of the supplementary drive system occur then the driver or some other “authorized” operation personnel will remedy the system by turning off a faulty traction bogie(s) 30 or by some other means. Assistance will be given by the support organization if the user cannot resolve the fault accordingly.

[0098] If a traction bogie 30 experiences a major loss of function, there will be two states available for the user. First the system can be set in a simplistic mode where drive/charge function follow a hardcoded sequence in order to give the train traction support at start/acceleration/ascending mode in order to complete the mission. The second state is a total shut-down of all functionalities of the traction bogie 30. Whether the train will be able to complete the mission without external added capacity depends on external infrastructure restriction or internal boundaries on factors such as freight tonnage and brake mass percentage.

[0099] At certain thresholds of the system assemblies and items life or condition specific maintenance activities will be conducted. Either inspection, cleaning, tightening/measuring of attachment part, lubrication, replacement of parts, overhaul and planned system upgrading/modifications will be done. Depending on activity certain skills or resources will be needed and work at intermediate level or depot level will be required.

Calculation of optimal drive and charge operation [00100] At start as well as continuous over the route the supplementary drive system decides the optimal charge and drive operation/procedure in order to fulfill the mission. Input data to the algorithm include train/system configuration, payload data, system status, route data (topology, speed limits etc.), timetable, GPS position and speed. The algorithm is based on logic, rules and conditions and optimizes the operation of the whole train system, i.e. , locomotive(s) 10 and traction bogie(s) 30, in conjunction with the infrastructure.

Traction (adhesion) contribution

[00101 ] When the supplementary drive system senses or becomes aware of a need for traction/adhesion support, it calculates where in the flock of traction bogies 30 and which amount of force is required and commands the individual traction bogie to act accordingly within the envelope of confined mission success parameters.

[00102] Adding sufficient traction contribution for train to reach ground speed within a certain timeframe, for e.g., train slot requirements, i.e., acceleration capability needs to meet certain requirements within a specific scenario/mission.

[00103] Adding traction contribution to maintain ground speed or keep train within allocated train slot in cruising and ascending segments of the route.

Deceleration contribution

[00104] Whenever there is a need for braking the traction bogie contributes by charging the batteries 36 and provide both braking force and adhesion.

[00105] This extra functional capability contributes to the whole train system with a higher brake mass percentage (break figure), thus increasing operational effectiveness by allowing shorter train slots or increased payload, for example.

[00106] This addition to the system's braking capacity also extend the lifetime of the conventional braking parts and prolonging maintenance intervals.

Balancing inter-train longitudinal forces [00107] Over an operating train system there are dynamic forces due to inertia which could lead to coupler fractures or other mechanical failures as well as derailment if not handled properly. The traction bogies 30 detect deviations through their sensors and apply traction or brake force where needed in the train system to balance the longitudinal forces in order for the system to operate more efficient. This could mean a higher payload allowance, higher ground speed over undulating/ascending/descending track segments.

[00108] In other words, a combination of simulated and calculated resultant forces will provide a basic instruction. These resultant forces are then compared in real time with real data, triggering rule-based decisions to accelerate or decelerate. In this way, the forces in each wagon will be balanced in order to at all time have forces below a level that may cause derailing. A side effect of this is lower wear on the couplings, reducing the need for maintenance.

System condition monitoring

[00109] The health of the different elements of the supplementary drive system is identified as necessary for optimal availability. The user will, through the control interface 56, continuously see the health status of the supplementary drive system. The user will be thus able to control the supplementary drive system and take suitable measures depending on health status.

[00110] At certain intervals or positions system data will be transferred to the organization responsible for maintenance and system support. Based on rules activities are triggered and planned by this organization.

[00111] Maintenance activities which have been planned must be scheduled and resources allocated. Actions are taken and the systems functionality and integrity restored appropriately.

[00112] The user will be able to control the supplementary drive system and take suitable measures depending on health status. Here will be certain modes of degradations allowed for the system to fulfill intended operations. Definition of tracks/lines

[00113] The definition of a line for which the train will run on is also based on rows in a table. An example of a table is shown below.

[00114] There are three properties that can be defined as function of position for a line: line speed, track gradient profile, and a bool that defines whether or not regenerative running of traction bogies are allowed while the locomotives apply traction.

[00115] Turning first to line speed, this is defined stepwise as function of position see the following table.

[00116] In this example, one can distinguish that at position 1000m, the allowed speed is 60 km/h, meaning that the train must slow down to this speed before reaching this point. Figure 6 shows a graphical example of what a speed profile could look like.

[00117] Turning to the track gradient profile, it is just as the speed also defined as function of position and is also defined stepwise in the same manner. The gradient is in this context in permille (%o) meaning that for a gradient of 6%o, the train will for each 1000 meter have gained 6 meter in vertical position. Note that the position of change in gradient does not have to be the same as the position in change of speed.

[00118] The third property is a bool that defines whether or not regenerative running of traction bogies 30 are allowed while the locomotives 10 apply traction. This can be used to charge the batteries on sections of line that is not demanding in terms of gradient. This will only affect the traction bogies 30 when the locomotives 10 are in traction. If the train needs to slow down or maintain speed in a downward slope, regenerative braking will always be activated on traction bogies at first hand. Just as for the gradient, the position of change in this bool does not have to be the same as for the position in change of speed, but one might adapt it to the change in gradient, since running regeneratively is probably not desirable in a steep upwards slope, since then the traction bogies 30 are actually braking the train.

[00119] There is a separate field next to the table defining the line. This field defines the wheel-rail adhesion and is defined as function of speed. The driver can choose between customizable functions, see table below. Simulation

[00120] The simulation program is based on simulation of a system of coupled equations, where each individual equation describes the movement of a single vehicle in the train. The system of equations can be solved with a suitable tool, such as an ODE-solver (Ordinary Differential Equation solver) in MATLAB®. The simulation is a time-step simulation with a variable step size. An example of how the speed of the train will follow the permitted speed is visualized in Fig. 7, which is a diagram corresponding to the one of Fig. 6 which illustrates how the simulation of the train is performed.

[00121] In the example, the train 1 starts at position P1 with an initial speed set to, in this case, the permitted line speed. The train 1 continues all the way to the next change in line speed, which is at position P3. At this point the simulation stops, the program checks the leading vehicles speed with the upcoming permitted speed. It is then determined whether the upcoming allowed speed is lower or higher. In this case it is lower. The program then simulates a braking from an initial guessed point P2, where the simulation is marked with a dotted, curved line. If the train brakes down so that the leading vehicle has the allowed upcoming speed at position P3, the braking simulation is completed. If the vehicle did not reach the right speed at the right position, the difference, i.e. , the distance between the point where we want the leading vehicle to have speed X and the point where the leading vehicle actually obtained speed X, is added to the initial guessed point P2 and the braking simulation is started again. This is repeated until the right point P3 is reached with the right speed, and the two simulated sections are then joined at P2. In other words, the simulation process is an iterative process.

[00122] The train then continues with a constant speed from P3 to point P4. At this point the simulation stops, the program checks the leading vehicles speed with the upcoming permitted speed. As the upcoming speed is higher the train will start to accelerate until it reaches the end of the section at P6. The program then checks whether the leading vehicles speed is lower or higher than the upcoming sections allowed speed. It is higher, so the train needs to slow down. The program then makes an initial guess of a starting braking point, which in this case happens to be in the acceleration phase. Just as explained above, the program iteratively finds the correct braking point and then joins the simulations.

[00123] As a further explanation of how the simulation data is handled during these sub-sections of simulations, the process is as following: A section of acceleration/constant speed is simulated all the way to the end of the section. Then the program always checks if braking is needed and if so, performs a braking simulation iteratively until the right point of braking initiation is found. After this, these two simulated parts are joined together to for example in Figure 7 above form section P1-P3. This finished sub-section is then appended to a final storage of all the vehicles states and other quantities. Then this process repeats for section P3-P4, P4-P6, P6-P7 and so on.

[00124] The equations are based on Newtons second law, which governs the movement of each vehicle. Equation 1 shows the equation, and what the different contributions are.

Equation 1 wherein a is the resulting acceleration a of each vehicle,

Fprod is the force produced by either traction or braking,

Fres is the running resistance that acts on each vehicle,

Fcoupi is the forces from the coupling, produced by the interaction between neighboring vehicles, and rrieq is the equivalent mass. [00125] The different parameters are now explained. The produced force F _pr od arises from either traction, in this case from electric motors, or from braking. The content of the F _pr od thus varies depending on if the vehicle is applying tractive force or if it is braking. We will here introduce three design guidelines that describe how the application of traction and braking will be performed.

[00126] During acceleration: When the speed of the leading vehicle is below the permitted speed, all traction vehicles 30 apply full traction force.

[00127] During constant speed: When the train 1 needs to maintain the permitted speed, the necessary tractive force needed to maintain speed will be spread equally among the locomotives 10. If so happens that the train runs in a downward slope with such a gradient that the train accelerates from the slope, the regenerative brakes in the traction bogies 30 will be activated first. If these are not sufficient, locomotives regenerative brakes are also added, followed by all mechanical brakes if so needed.

[00128] During braking: When the train is to brake due to an upcoming speed restriction, all producible braking force is applied in accordance with the settings of the type of brakes.

[00129] Reading this, one could also conclude that the simulation is designed to minimize running time while at the same time optimizing the usage of traction bogies 30 to be able to use these for increased acceleration.

[00130] Let us now go through how the force F _prO d in Equation 1 from traction and braking is calculated.

[00131 ] The traction is in the simulation based on the characteristics of electric motors. The equation governing the tractive force produced is very simplified and does not consider all the real aspects of an electric traction motor. The tractive force produced is calculated as the (rated) motor power divided by the vehicle speed,

Equation 2

[00132] At lower speeds, the tractive force is restricted by wheel-rail adhesion, meaning that Equation 2 is not followed. Fig. 8 presents how the calculation of the tractive force of a locomotive is done in the simulation. The vehicle is defined together with its rated power and a maximum producible tractive force. This maximum force, which can be defined for each vehicle, puts a “cap” on the tractive force in the lower speed region below the base speed. Above the base speed, this maximum tractive force cannot be achieved due to limitation in the power, leading to a decrease in traction force according to Equation 2 (increasing speed while keeping the power constant must lead to reduced producible traction force). The base speed is found automatically as the speed for which the produced tractive force equals the defined maximum tractive force.

[00133] The calculation of the braking force is done as follows. There are four different braking modes, where these four modes result in three different equations for the calculated braking force, which is showed in Equation 3.

[00134] Equation 3

[00135] The first case is where electrodynamic braking is allowed. The braking force is the same force as for traction, but now with opposite sign. Note that the same restriction regarding maximum force at low speeds holds, see calculation of traction force above. The second case is where mechanical brakes are also active. In this case, the braking force is calculated as the adhesion times the normal force, which in turn is the adhesive mass times the gravitational acceleration. When the vehicle runs unbraked, a braking force equals to zero. Running resistance

[00136] The term running resistance will now be explained. During simulation this comprises three components: aerodynamic resistance, gradient resistance and rolling resistance as showed in Equation 4, and these components will be explained below in detail. Equation 4

Aerodynamic resistance(drag)

[00137] The aerodynamic resistance has several parts, where these are showed in equations 5 and 6. 5 6

[00138] Equation 6 is also called the resistance area which is a quantity that is neat to use when the cars have an unknown cross-sectional area. The last part of the equation, which contains two constants a and b, is what we will use in this software. It allows us to define the resistance area as linear function of train length, with an added constant.

Gradient resistance

[00139] The gradient resistance for each vehicle is the static mass times the gravitational constant times the gradient, as showed in Equation 7. Note that the gradient is defined and inputted in permille, thus the division by 1000. Equation 7

Rolling resistance

[00140] The rolling resistance stems from different phenomena involving energy losses due to friction. Some of these are:

Axle bearing friction

Energy losses in the wheel-rail contact

Energy dissipation in (mainly) dampers and friction surfaces

[00141 ] This resistance is calculated differently depending on if the vehicle is a traction unit or a non-powered wagon. For traction vehicles, the equation used is while for freight wagons the equation is where ao is approximately 0.4 for idling electric commutators without motor current, and zero in all other cases. Due to avoidance of unnecessary complexity, this value is set to zero.

P is the rated power for the vehicle. a is a so-called starting resistance, and this value is set to 2 at speeds below 0.5 m/s. For higher speeds, this value is set to 1 .

Naxies is the number of axles in the vehicle. ao and bo depend on the quality of the track and the dynamic properties of the vehicle.

Qi is the load on each axle, in the preferred simulation the static mass divided by the number of axles. v is the vehicle speed

Coupling force

[00143] The coupling between each vehicle is modelled as a linear spring and damper model with the spring and damper coupled in parallel. There will be three cases for which forces will act on a single vehicle. The first case is for the leading vehicle. In this case there is only a coupling to the vehicle in the rear. The second case is for all the intermediate wagons; they all have couplings to vehicles both in the front and in the rear. The third case only applies to the last vehicle, where in that case there will only be a coupling to the vehicle in front. See Fig. 9 for an illustration. The coupling force consists of two forces between each vehicle, one from the spring and one from the damper.

[00144] For the first case, the leading vehicle, the coupling force is Equation 10

[00145] Note that the sign is negative on both terms, which can be confirmed if one visualizes what will happen if the leading vehicle applies traction force and tries to pull away. The following vehicles will counteract this movement. For the intermediate vehicle, additional forces will be introduced from the preceding vehicle,

[00147] The sign from the first coupling is now positive, and the rear coupling is negative. For the last vehicle, the equation for the coupling force is

Stored quantities

[00148] There are several quantities that are of interest to store to be able to present in the Plots and Statistics program as well as the Animation program. The following quantities are stored for each vehicle:

Position.

Speed.

Acceleration.

Traction force.

Coupler force.

Running resistance (aerodynamic, gradient and rolling resistance together, F_res as showed in equation 4:4).

Utilized adhesion. Note the difference between available adhesion and utilized adhesion.

Power consumption.

Accumulated energy consumed/stored.

[00149] Also, the total kinetic energy and potential energy (relative to the height of the starting position) is stored as function of time.

Simulation Program Graphical User Interface

[00150] The GUI (Graphical User Interface) for the simulation program is designed so that the user can load the predefined train and track from separate data files, get a brief summary of the information in these files and then also be able to modify some settings for the simulation. [00151 ] Once you have chosen your train and track file you can define whether the train shall start at the defined line speed or from standstill. Then there are four settings regarding the equation solver used.

[00152] Time step: This dictates the maximum time step that the solver will use. Note that the solver will modify the time step to a smaller value at those instances for which it is needed to obtain an accurate solution

[00153] Relative tolerance & Absolute tolerance: These values control the accuracy in the solution. I.e. , they determine the largest acceptable error in the solution, where the error is the difference between the estimated and true values of the states (states are in this case the position, speed and accumulated energy consumption of the vehicles). This error is compared with the relative tolerance and absolute tolerance, and if the solution does not meet the tolerances, the solver reduces the step size and makes another try.

[00154] Solver: The type of solver used to integrate the equations of motion and obtain a solution.

[00155] Lastly you can choose a name for the output file, which will be data file, and you can also define the sheet name in which you want the results written.

Output file

[00156] The output of the program will be a folder (with a name as chosen in the GUI). This output folder will contain PDF file with graphs and statistical info of the quantities earlier listed.

[00157] The diagram of Fig. 10 shows the accumulated energy as function of time for each vehicle. The kinetic and potential energy are not shown in the diagram. In this example the leading vehicle was a locomotive and vehicles 9 and 10 were traction wagons. Note that the meaning of the accumulated energy differs between locomotives and traction wagons. For locomotives the accumulated energy shows the net consumed energy (and can thus become negative due to regenerated energy), while for the traction wagons the accumulated energy is the stored energy onboard the vehicle, and cannot become lower than zero, and cannot exceed the specified value for maximum storage capacity specified in the train data file.

[00158] The diagram of Fig. 11 is a presentation of the leading vehicle speed and the leading vehicle height in relation to the starting point. Having this graph next to the graph in Fig. 10 showing the quantity makes it easier to interpret the results. Focused has here been on the accumulated energy quantity, but the presentation of the other quantities follows the same design.

[00159] Preferred embodiments of a supplementary drive system according to the invention have been described. It will be appreciated that they can be modified within the scope of the appended claims without departing from the inventive idea. Thus, vehicles provided with bogies have been described, but it will be appreciated that the inventive idea is applicable also to vehicles having fixed axles.

[00160] In the example shown in Fig. 2, all wagons are traction wagons 20, but it will be appreciated that the wagons of a train may be a mix of conventional wagons 20’ and traction wagons 20.