System structure for radio- or wire-based communication system

Transcription

1 FEBIS System Aspects Within the FEBIS-Project (Freight Electronic Brake and Information System) the railways DB AG and SNCF develop with the industry-partners SAB Wabco and Alstom a communication system and a electronically controlled brake. This shall enable the railways to overcome today s limitation in length and speed of freight trains due to performance limitation of existing brake systems. The aim of the development process will be an interoperability specification (which could be base for a standard) that should enable other industrials to manufacture components and vehicle equipment s compatible with FEBIS. Overview When trying to introduce electronic systems into freight trains, two new aspects have to be solved first: communication within the freight train and electric energy in the wagons. These two features are the basis for distributed electronic systems and should therefore be implemented in a way, that based on the now developed FEBIS solutions, future extensions are possible. Typical future system extensions that one can already easily think about, are e.g. systems to monitor the status of goods transported or sensor systems supervising the wagon or the multiple traction based on FEBIS communication The today s FEBIS system developments are based on a wire-bound and a radio-bound communications system as summarised in Fig. 1. This communication channel running through the train, is called a Trainbus. System structure for radio- or wire-based communication system The electronic systems in the vehicles have to be connected to the Trainbus. There are different kind of topologies possible for this. Two examples are: 1. A central vehicle node is connected directly to the Trainbus and all the functionality is implemented in this central electronic node. 2. A second approach is, to have inside the vehicle a internal communication system, the vehicle bus and electronic systems performing specific functions are connected to this vehicle bus. Both solutions shall be possible and will be realised within the project. The energy supply required for the electronics is supplied either centrally from the locomotive by means of cable or locally by means of axle-mounted generators (in the case of radio).

2 It is also pointed out in the picture, that there could be more than one connection point to the trainbus in a vehicle. This is true for the locomotives, where we find a connection to the system part, which realises master-functionality s in the train and one or more nodes, at which e.g. the electronic components for the brake control is embedded. This structure makes it possible to brake a switched off locomotive in the train like a wagon. As the communication and energy system by itself has nearly no benefit, these systems are the base for applications performing special functions or activities. The first and primary application developed in the project is the electronically controlled brake. The brake command is transmitted via the trainbus and the conventional compressed-air brake assumes in the first place only as a backup and source for pneumatic energy. Due to this system the brake test can be automated and in all the vehicles apply and release of brakes can be monitored. The brake pipe is in the FEBIS system turned into a main pipe and feeds the brake equipment with compressed air. Another integral part of the development project are also variants for train integrity monitoring, which provide ERTMS capability - one by means of an EOT device to be fitted manually and as alternative a fully automatic one with relevant sensors, or a half-automatic one with human decision. The concept of distributed Applications To be open in order to scope with these various future requirements, the FEBIS development uses the concept of applications, based on the communication system, which is offering communication services to the applications. A Distributed Application is an application, involving more than one node on the network. The Distributed Application executes functions specific to the system (i.e. Brake Control application, Multiple Traction application, Train Integrity application, Train Diagnostic application ). Each Distributed Application is managed by its own specific Application Master. The Application Master is a task that manages the Distributed Application activity: in other words, it sends commands to the Distributed Application and, depending on the application, may expect responses from it. The Application Master can run either on the leading locomotive (together with the Master of the communication system), either on a remote node. There is only one Application Master allowed to be active for each distributed application at the same time. Nevertheless it will be possible for some applications (not for the brake) to have a redundant master and a change of master initiated by the application itself. In the Project only the brake application will be developed. For the brake application there will be a unique Brake-Master who has to be located at the leading locomotive.

3 Concept of application for the FEBIS development For the identification and installation of application a unique identifier is used. If two nodes found the same application identifier connected to the communication system, they are supposed to be able to communicate. If it is not the case, the application itself must solve the problem. The rules of definition of identifiers for future applications have to be described in the standard definition, and will become a part of the interoperability. This has to be defined by Administrations. System Aspects of the Communication system Due to the concept of distributed application and the open system approach, there are requirements to the different parts of the system, especially to the communication system, as it takes the role of the backbone of the system. It will be necessary to have the possibility of node addressing. This node addressing should be related to the position of the node in the Train (wagon specific, one wagon could have more than one node). It is also the necessary to know about the orientation of the vehicle (for multiple Traction, e.g.) This information has to be build during the process of initialisation, we say during the train inauguration. The initialisation of the different applications has to be done after the inauguration process. During train inauguration the applications on the train have to inform the communication system about their communication needs. The Communication system will use this information, to assign communication bandwidth to the applications The communication system must allow the applications to have a quasi deterministic communication and it must also provide the possibility of asynchrony communication, especially in the case of alarms. This means, the communication system must offer a multi-master capability for the network access, like the LON technology does. The communication system has to be a open one with well defined interfaces. It should be possible, that future new application can be added without changing the implementation of the communication system

4 It should be possible to run applications, were the Master of this application is not located at the leading locomotive. It is necessary to have always a view on the state of the communication system Wired Solution In the FEBIS Project the wire-bound train bus system is being realised on the basis of LON technology from the American company Echelon with LON power-line-data transmission, i.e. energy and data are transmitted on the same line here and the fritting problem in the connectors is solved by this way. For FEBIS, not just one line is used for this purpose but two. The communication behaviour on this two lines should be same. The redundancy in the wiring increases on the one hand availability and data rate and on the other, also the energy provided on the individual vehicles can, if necessary, be doubled. For the communications protocol a master/slave approach with a determined behaviour is scheduled. The multi-master capability of the LON communications - that means that every subscriber can transmit when it wants to - is used for emergency messages. Through the existence of two data networks, a distinction is to be made between "vital" functions, such as braking and traction control, and additional applications, such as diagnostics and monitoring functions. In this philosophy the one bus for train control functions could be a closed one and only be allowed for special applications, and the other bus could be open for future new applications. Radio Solution The radio-based communication system is intended to make it possible to contact each vehicle in the freight train, in spite of there being individual, non-equipped vehicles in the trainset. For the implementation of this system, each vehicle is equipped with a radio node and antennas are mounted to the sides of the vehicles. The objective is to attain a working range of approx. 100 m, even with low transmitting power, and thus to "skip" individual vehicles within the train. In order to be able to provide an optimum configuration of the communication characteristics in track curves, each side of the freight wagon is fitted with an antenna. Which antenna or which side of the freight train is used can be selected by the communication system during the telegram propagation time depending on the ambient influences. Concept of Traintalk radio communication used for the FEBIS prototypes

5 The protocol to be used in the FEBIS prototype trains is the TrainTalk protocol developed by GE Harris and uses hardware components for transmission in the 5.8 GHz ISM frequency band from ST2E. This parts will be integrated into the electronic of SAB Wabco and Alstom. Train Integrity Another function, which can be seen in connection to the communication system, is to check the integrity of the Train. At least there are three parts of integrity, which should be mentioned: The train integrity in the sense, that all vehicles in the train are known, the integrity of the communication and energy line and the integrity of the brake pipe. The check of the train integrity will be done, by defining the first and the last communication node in the train and by ensuring, that this two nodes really belong to the first and the last vehicle in the Train. These nodes will send periodic information, which can be used to define, that the train integrity is still given. To prepare this, it has to be ensured, that the nodes used for the train integrity do really belong to the physically first and last wagon. For this in den actual FEBIS development two solutions are going to be realised: 1. EOT A: As a first solution, a separate End of Train device will be put on the hook of the last wagon. Due to this it is clear, that no other Wagon can be connected and this device indicates the last node in the communication system. 2. EOT B: In this solution the communication system detects the last communication-node in the train. The driver has to confirm, that this node belongs really to the last Wagon in the train and after this confirmation, train integrity can be checked. A third solution is the one, where the vehicles by using special sensors can detect by themselves, that there is no other wagon behind. This solution is even possible and in the project known as EOT C, but it will not be realised at this stage. System aspects of the Energy system For the energy-system two approaches are possible. In the first one, there is a central power source and the Energy is transmitted using power lines running trough the train. This solution is applicable if a wired communication system is used. The alternative solution is a vehicle autarky Power supply, which is at least necessary for the radio based communication system. In both cases, there are some requirements, which have to be fulfilled: A local energy storage is necessary in order to allow the electronics to survey 5 hours without recharging The local energy store should enable the system to be restarted (wake up) even after a none used stand still time of 5 month. Energy in radio mode For the radio solution, the freight vehicles will be supplied with energy from axle-mounted generators and corresponding batteries so that a system with a self-supporting vehicle can be realised and tested. For this solution the question of power generation and distribution is clear. For the layout of the axle generator it has to be clear, that the generation of Energy can only be done during the time, the vehicle is moving. The system layout is done on the estimation that not more than 10% of the operation time of the system can be used to recharge the batteries.

6 Energy in wired mode For the wired mode, the energy will be generated on the locomotive and by means of cables transported to the vehicles in the train. The different aspects of this system shall be described in the following part. Energy generation The energy generation is attributed to the leading locomotive: the leading locomotive will be equipped by a Power Supply able to feed the complete train. The power supply output voltage is the result of a compromise between the minimisation of the power dissipation along the distribution power line and the safety for the users : in other words it is high enough to not have heavy voltage drops at the maximum power distribution and shall be limited under a value where the insulation costs is still acceptable for the product. The chosen value is 230Vdc : as demonstrated in the following, this value is allowing a quite good efficiency in the power distribution. At the same time, this value guarantees limited costs and dimensions in the related materials (insulation s in the circuits, capacitors voltage range, active components in the distributed DC/DC converters). Only one line will carry 230 VDC. The other line will be feed with 48 VDC As the 230 Vdc are a risk for people if this Voltage is touched, it is only allowed to put Voltage on the line, when the line is closed on both sides of the train (line integrity). This means, the connector has to be put into a host box or another device like the described EOT A. If line integrity is lost (connector out of hostbox), or train integrity is lost (e.g. network broken), this state has to be detected and communicated to the power management. In this cases the 230Vdc have to be switched off by the system immediately. The locomotive power supply can be fed by any kind of energy source present on the locomotive : whichever this source is, the locomotive power supply output circuit is submitted to galvanic insulation from the energy source. The power supply output can be switched on/off under FEBIS system command. Reasonable precautions are used against input and output over-voltages. It is planned for the system, that energy is only put on line from the leading locomotive. Energy storage The energy storage will be achieved by means of batteries distributed on each wagon. The capacity calculation must be performed taking in account the following requirements: Unit wake-up after 5 months inactivity on field 5 hours autonomy after wake up without recharge operative temperature range of 40 C to +50 C. To properly dimension the battery capacity an important issue is necessary: the wagon unit consumption in sleep mode and in alive mode. These parameters are strongly dependent on used electronic, sensors and valves. Energy distribution The energy distribution will be achieved by means of the power lines running along the train. The wires section has been chosen large enough to not create excessive voltage drops during the energy distribution. At the same time the section shall allow the wire to be installed without major limits in the cable flexibility.

7 One of the most critical points in terms of voltage drop are the connections: connections between wagons, interruptions on the wagons themselves (called Junction Boxes), necessary to derive energy and communication. The resistance of these connection/interruption points must be in the order of magnitude of few m. A special feature is requested to the connector between the wagons : to help the automatic train separation this connector shall be able to uncouple by pulling it. The present choice for the Prototype train is the TriStar connector, but other solutions are also under investigation. As two powerlines support the FEBIS system, two connection points will exist between a couple of wagons. If railways see, that for different reasons a solution with only one connector has more advantages it could be, that only one inter-car connector could exist, carrying both the Power Lines: this particular issue shall be analysed with care, due to crosstalk interference problems between the two networks. The estimation for fixing the power distribution some calculations shall be provided. By fixing the train tail minimum voltage at 100Vdc, it is possible to calculate the maximum power available per unit. Some simulations have been done, where: wire length per wagon is assumed 22m (2250m/125 +4m spare) connector resistance is assumed 20m drops on the Junction Boxes is assumed 5 m double wire cable resistance is assumed to be 7m C Here follows some simulation results, where 12W are attributed to each unit: Estimation to voltagedrops and currents in the powerline based on simulations done by SWAT

8 This case must be assumed as the worst, and give indication about the fact the maximum deliverable power per unit is 12W: the design of the wagon power supply shall ensure high transfer efficiency, in order to guarantee enough power for the electronics and the battery charger. In the previous example, it must be noticed that the power delivered by the locomotive is approximately 2500W. The total system efficiency can be evaluated as: 12W 125 TSE W In this worst case the Power Line will dissipate 1000W for the distribution. Application Brake The Application Brake is the first application, realised within the FEBIS project. The aim is to build a electronically controlled brake for a train up to 2250 m. The brake and release times should be even for such a long Train comparable to those today available in P-Mode. As such a long train can not be stopped in a save way with the UIC brake behaviour in all cases, FEBIS must under this circumstances ensure, that such a FEBIS train can be stopped as save as today. This is one of the main new aspects of this electronically controlled brake. As opposed to the UIC ep brake, no main air reservoir pipe is required here to achieve the ep braking and release characteristics. Development of the application "brake" is however being effected as a so-called overlay solution, i.e. the vehicles fitted with an electronically actuated brake can also be incorporated in conventional freight trains. The complete additional pneumatic functionality will be integrated into a so called pneumatic flange, with can be easily added to the pneumatic equipment already installed on the vehicles. Summary To realise a solution to overcome today s limitation for train length, the FEBIS-Project develops a electronic controlled pneumatic brake and a information system for freight trains, suitable for train length up to 2250 m. The system is always developed in a way, that we first realise an open communication system, which can serve as a communication channel for different distributed applications; based on this, the brake system will be the first application implemented. The realised elements of the project can be seen in the last overview picture, where the layout of a locomotive is shown, which includes all the relevant elements (in this example for the wire solution without vehicle bus) We see on the locomotive Master side the Air generation and the electrical power generation, MMI and the operation lever for brake and emergency. A Master control unit, in which the Master functionality of the communication system, the Brake, and the Power management is included., which is summarised in the MCU. On the wagon part, for the solution without vehicle bus, the electronic components are integrated into a Local Control Unit. Within this LCU different tasks are fulfilled like communication, brake control and energy management. The interface for the pneumatic brake are realised using the pneumatic flange.

9 It should be mentioned, that for the development and test of this system, a pneumatic test bench was build from SAB Wabco (Italy) with a pneumatic length of 2250m. Here the complete System will be tested and validated before railways equip wagons and locomotives. Febis system structure, all elements can be found in one locomotive Literature /1/ Barberis, Grenier: Sistemi innovativi di controllo del freno per il mercato europeo del trasporto merci, Ingegneria Ferroviaria 10/98, S. 715ff /2/ Gralla: Ein neues Bremskonzept - Voraussetzung für die automatisierte Güterbahn, ETR 44 (1995) Heft 4 /3/ Guillaumin: A revolution in freight train braking has begun, IRJ April 2000 /4/ Sonder: Elektronische Bremsabfrage und -Steuerung <EBAS>, ZEV+DET Glas. Ann. 122 (1998) Heft 9, S. 481ff /5/ Sonder: Elektrisch/elektronische Bremsabfrage und -Steuerung für Güterzüge, ZEV+DET Glas. Ann. 119 (1995) Heft 11, S. 505ff /6/ TrainTalk Wirefree Communications System, ERRI Conference for High Productivity Freight and ECP Brake in Europe, Feburary 4-5, 1998 /7/ Witte: CAN in Güterzügen, Elektronik 20/1998 /8/ Witte, Minde, Engelmann: Zentrale Komponenten eines Intelligenten Güterzuges, ETR 11/2000 /9/ Witte, Kleinsorge, Meier; Funkkommunikation im Güterzug, Signal+Draht, März 2001 /10/ Minde, Witte: FEBIS Kommunikationsbasierte elektronisch gesteuerte Bremse, ETR 50 (2001) Heft 5, S S.263.