01_ Automation for W50DF

1 © Wärtsilä 27 September 2007 W50DF08V00BTM09A Rev. 01

08 AUTOMATION SYSTEMWÄRTSILÄ W50DF

WECS 8000


08 AUTOMATION SYSTEM

WECS 8000

The DF engine concept by itself isbased on fuel redundancy. Inaddition, WECS 8000 is totallydistributed, in order to split upfunctionality and make boundariesbetween the categories control andmonitoring, but also to build naturalredundancy into the system. Thismeans that redundancy controlstrategies are utilised, in the eventof a main sensor/componentfailure.

The conceptWECS 8000 is an engine built,distributed control- and monitoringsystem specifically developed byWärtsilä to meet the performancerequirements set out for enginesusing genuine Dual Fueltechnology.

It handles all strategic functionalityrelated to operation both on gasand diesel fuel (such aselectronically controlled gasadmission and pilot fuel injection,diesel actuator control, enginesafety and fuel switch-over logic).

The design

All the modules communicate witheach other via an inter-modulecommunication bus based on theCAN protocol. CAN is acommunication bus specificallydeveloped for compact localnetworks, where high speed datatransfer and safety are of very highimportance.

Some safety critical back-upfeatures such as overspeedprotection is handled by the relaymodule (discrete cabling).

The communication

General



Automation system arrangement

Fig. name: Automation system on engine manoeuvring side

The WECS 8000 system is a fully integrated enginemanagement system, designed for harsh environments.The engine-built system handles all necessarymonitoring- and strategic control features needed on a DFengine. The system architecture is based on distributedelectronic modules, thus the measurements and controlsare occurring where locally needed on the engine. Thefunctionality of WECS 8000 comprises the following maincategories:

Handling of engine slow turning, start & stopsequencesChanging of fuel modesInstrumentation & communicationSpeed measurementEngine safetySpeed/load controlGas pressure- & gas admission controlPilot pressure- & pilot injection controlAir/fuel ratio controlCylinder balancing& knock controlDiagnostics

System components01 Local control panel02 Actuator03 CCM-10, Cylinder control module (1-n)05 Cable rail06 Main cabinet




Fig. name: Automation system on engine rear side

System components02 Power module03 CCM-10, Cylinder control module (1-n)05 Cable rail

The system consists of a number of distributedelectronic modules, all interconnected with a multibus.The exact structure of the system depends on theengine’s cylinder configuration. The electronic modulescommunicate with each other over a communicationbus, and this communication is based on the CAN(Controller Area Network) protocol.Some safety critical back-up control functions arehandled over hardwired point-to-point wiring, and witha separate back-up module.




Fig. name: Automation system on engine at free end

System components04 MCM-700-2, Main control module05 Cable rail



Fig. name: System architecture, V-engine

Automation system arrangement01 Local control panel

Graphical displayControl buttonsEmergency stopBack-up instruments

02 Main cabinetMain control modulePower moduleRelay moduleDiesel actuator converterCAN repeaterModbus port

03 Cylinder control modulesMain gas admissionPilot fuel injectionCylinder measurements

04 Main control modulesData acquisition

05 Actuator

06 CAN communication bus



Local control panel

Fig. name: Local control panel

There is a local control panel on the engine, wheremost engine measurements and statuses can bemonitored, and where the local push buttons andselector switches are located. For viewing of theengine parameters, there is an electronic LDU (LocalDisplay Unit) used, with a number of menus andmenu selection buttons. Mechanical back-upinstruments for engine speed, HT water temperatureand lubricating oil pressure are also arranged. Thelocal push buttons and switches are the following:

System components01 START button02 STOP button03 Emergency STOP04 Shut down RESET button05 Remote/Local mode switch06 Speed increase/decrease switch07 Local display unit08 Engine speed indicator09 HT cooling water temperature indicator10 Lubricating oil pressure indicator



Local display unit

Fig. name: Front view of the LDU.

The LDU replaces the traditional pressure gaugepanel, thermometers and other engine instruments.The LDU is connected to the main control moduleover the CAN bus, over which it receives all data tobe displayed. The graphic display has a number ofdifferent pages (menus), and integrated key buttonsfor activation of these pages.

System components01 Graphic display02 Main page03 Alarm log04 Help page05 Back command06 Navigation07 Enter command08 Engine temperatures09 Lube oil system10 Fuel system11 Cooling water system12 Charge air system13 F6 + F1 Miscellaneous measurements

F6 + F2 Knock measurement



Main cabinet

Fig. name: Main cabinet

System components01 MCM-700 Main control module02 Electronic unit, CAN-repeater03 Converter04 Converter05 Converter06 Converter07 Converter08 Hour counter09 RM-11 Relay module10 DC/DC converter11 Converter12 Signal isolator/converter



MCM-700 Main control module

Fig. name: MCM-700 Main control module.

This module is the master in the WECS 8000system. It handles the processing of all strategicengine control functions. The main processes arethe engine start- & stop sequences, engine safety,and the combustion control. Calculations are madebased on the internal speed/load control algorithms,gas pressure, gas admission and pilot fuelinjection/timing. It handles the information sent byall other modules, and it sends reference signals tothe cylinder control modules about gas admission,pilot fuel quantity and timing etc. It alsocommunicates with systems external to the engineitself. A second MCM-700 module is also part of thesystem (at free end), exclusively for collecting ofsensor signals and for control of the waste gate.



CCM-10 Cylinder control module

Fig. name: CCM10 Cylinder control module.

The cylinder control modules control the gasadmission- and pilot fuel injection valves by meansof using high-energy type PWM (Pulse WidthModulation) outputs. Each module is providingPWM-type control signals to three gas admissionvalves and three pilot fuel injection valves. Themodules calculate the relevant injection durationand injection timing based on references sent overCAN from the main control module. In order toprovide injection command signals at the relevantangular position, the cylinder control modules needaccurate information from the engine’s speed andphase sensors. Therefore the speed and phasesignals are hard-wired to each cylinder controlmodule. The cylinder control modules also handlecylinder specific measurements, i.e. exhaust gastemperature and cylinder knock measurements. Allcylinder specific information as measured by thesemodules is sent over CAN to the main controlmodule.



Actuator

Fig. name: PG-EG 200 actuator

This hydraulic-mechanical actuator is used indiesel- and back-up operating mode, for controlof the fuel rack of the engine. The actuatorreceives a control signal from WECS 8000 maincontrol module (via a current converter), andsets the fuel rack position accordingly.



Cabling and CIB (Cabling Interface Box)

Fig. name: CIB enclosure used for interconnections and cabling

Interconnections and cabling on the engine isutilizing a so called cabling interface box, CIB, whichis acting as an interface between the controlmodules and their peripheral devices.

The CIB is a robust construction mounted on top ofthe control modules, it’s equipped with cable glandsfor the out-going cables and with multi-pinconnectors for mating to the control module.Internally there is a printed circuit board containingspring loaded terminal strips, test connections,terminal resistors etc.

Screened, special cables for the demanding engineenvironment are used for all equipment. Controlmodules are interconnected with a special multi-buscable, including power supply (24V), engine speed,engine phase, safety wire loop and CAN-bus, alldoubled for redundancy reasons.



Fig. name: WECS 8000 system overview

An overview of the entire cabling ofthe DF engine, includingreferences to each sensor.

Cabling and CIB (Cabling Interface Box)WECS 8000 system overview



WECS 8000

Fig. name: WECS 8000 system communication and signals

WECS 8000 is a distributed system, where all theelectronic modules communicate over the CAN-buswith each other. The system collects signals fromvarious sensors at different locations on the engine,connected to locally mounted modules. The signalsreceived are processed and compared with the controlparameters given for all the active engine processes.

Internal and external communication on DF engines

These engine-strategic controls are processed inone of the two main control modules, which is themaster of the system. This main control modulealso automatically controls the start- and stopsequences of the engine, as well as monitors theengine safety.The second main control module is exclusivelyused for collecting of sensor signals and forcontrol of the waste gate.Several cylinder control modules are used, eachmodule handles 3 cylinders. All the modules aremounted along the engine side close to the enginesensors or the control units they are reading orcontrolling. The data transferred over CAN betweenthe modules, has a number of different rate groups foroptimised and secured data transfer.



RM-11 Relay module

Fig. name: RM-11 Relay module

Unlike other parts of WECS, the RM-11 relaymodule electronics is based on analogue circuittechnology (no microprocessor). The relay module,which is located in main cabinet A1, handles anumber of back-up safety related functions on theengine. It also constitutes the hardwired interfacebetween the main control module and the start-slowturning- & stop solenoids of the engines, andpartly also to the external systems. Criticalparameters such as engine speed, lubricating oilpressure and HT water temperature are monitored inthis module, and in case of abnormal levels, a shut-down is initiated and controlled from this module,independently of the main control module. The relaymodule is located in the main cabinet of the engineand LED’s on it indicate the status of eachinput/output of it. Also all supply voltages have theirown LED.



Power distribution and filtration

Fig. name: PMOD cabinet

The power module (PMOD) is a separate cabineton the engine, that handles the power distributionand filtration within the WECS 8000 system. Onthe front of the cabinet, there are separateswitches for disconnection of the 24 VDC systemand the 110 VDC system. Both the main and theback-up voltages for both these DC-systemshave green lamps on the front of the PMODcabinet, for indication of presence of inputvoltage.

System components01 Rectifier02 DC/DC Converter03 EMC Filter04 EMC Filter

PMOD cabinet



Fig. name: Principal design of the PMOD

The external 24 VDC power supply enters thePMOD via two separate inputs. The two 24 VDCpower supplies are via diodes inside PMODconnected to an EMC-filter. There are separatedistribution lines from the PMOD to each sub-module, all having an individual fuse.

A separate voltage of 110 VDC is in WECS 8000used as drive voltage for the high energy solenoids(both gas admission valves and pilot fuel inj. valves).The external 110VDC power supply enters thePMOD via two separate inputs. The two 110 VDCpower supplies are via diodes inside the PMODconnected together into one single supply. Thissupply is then via a bi-directional EMC filter and afuse connected to the cylinder controllers.

Internal connections of power module




Fig. name: WECS 8000 power distribution principle

The power supply lines are “looped” around theengine, to provide safe supply in case of a singlepoint wire break. Beside figure which shows thisdistribution principle.

WECS 8000 power distribution principle




Other parts of WECS 8000

A CAN repeaterThis signal repeater extends and isolates galvanically the CAN-bus outsidethe engine. This external interface is to be connected to an externalconfiguration, calibration & diagnostic tool (PC program), used byauthorised personnel only. The transfer rate is 500 kbit/s.

A media converterThis converter is used to convert the external communication bus signal(Modbus TCP/IP) from an electrical signal (from LDU) to a signaltransferred optically through an optical fibre (to plant automation system).The transfer rate adapts itself according to the device used externally to theengine, and will be either 10 Mb/s or 100 Mb/s.

A current converterA current converter for the actuator. This signal converter module convertsthe proportional 4-20 mA signal from the main control module to a 0-200mA signal used by the actuator.



Engine speed measurement

The purpose of this measurement in WECS 8000 is:As position feedback to provide accurate gas- & pilot injection timingAs speed feedback to the internal speed controllerAs speed feedback in internal parameters tables.

Both the speed and phase measurements are redundant.The speed signal pulse train contains a missing pulse, used for determination of engine’s TopDead Center.The purpose of the phase measurement is to determine which of the missing pulses is relevantfor TDC of cyl. (A)1.

Engine speed/angular position measurement




Fig. name: Engine speed- and phase signal distribution

The engine speed is measured, based on thesignal from two speed sensors. Both speedsensors are connected directly to the main controlmodule (MCM-700), where the speed calculationis carried out in.

For the gas admission- and pilot injection timingprocessing, the cylinder control modules (CCM-10)need accurate information about the engine speedand engine angular position. Therefore the enginespeed- and phase signals are connected to eachcylinder control module, for this calculation. Thesesignals are hard-wired to each module, i.e. nottransferred as data over CAN.

For redundancy reasons two speed sensors andtwo phase sensors are connected to each cylindercontrol module.

Speed and phase signal connections on engine



Fig. name: 120 – 1 bored speed-sensing holes in the flywheel

As WECS 8000 must detect the accurate engineangular position, one missing hole is arranged inboth speed sensing hole-peripheries on theflywheel, i.e. the pulse train will contain one missingpulse for each engine revolution. The angularlocations of the missing holes are such, that theend-edge (= positive electrical flank) of the holecoming after the missing hole, is accurately at TDC(Top Dead Centre) of cylinder (A)1. The speedsensors use separate holes, but the holes are “inparallel”, thus the phase difference between the twosignals is negligible. The number of holes is 120minus the missing one, i.e. 120 – 1.

Engine speed measurementSpeed and TDC measurement



Fig. name: Missing hole location, and speed signal pulse train

The sensing gap for these engine speed sensorshas to be 2,5 mm ± 0,2 mm. The speed signalpulse train from the two speed sensors will have theshape as in picture below. This signal is connectedto all cylinder control modules, as well as to themain control module. The main control modulehowever, has no use of the TDC information, onlythe speed level.

Engine speed measurementSpeed and TDC measurement



Fig. name: Location of phase sensors

As the engines controlled by WECS 8000 are 4-stroke engines, the crankshaft and thereby flywheelwill make two revolutions for one complete enginecycle. To detect which TDC marker signal (missingpulse) belongs to the working phase of cylinder A(1),also engine phase detection is needed. Two phasesensors are provided of redundancy reasons. Thesesensors are mounted at the driving end of thecamshaft of the engine. These sensors are PNP-typeproximity switches.

The phase sensors are detecting the “phase” of theengine by means of detecting the position of a “half-moon” disc, attached to the driving end of thecamshaft. This disc is mounted in such a way, that apositive edge (signal going high) will occur 180BTDC of cyl. (A)1, and will remain high until 180ATDC for the same cylinder, see picture below.Based on whether the phase signal is high (24 VDC)or low (0 VDC) when the missing pulse comes,WECS can exclude the false missing pulse. Only themissing transition coming while the phase signal ishigh, is in WECS defined as true.

Engine speed measurementEngine phase measurement




Fig. name: Speed and phase signal traces

Speed and phase signal traces



Fig. name: Engine modes

General

Engine modes

The WECS 8000 engine management systemcontrols and monitors the engine parameters andinitiates all required actions in different situations.These actions can vary from giving an alarm to theoperator, to shutting down the engine. Depending onthe status of the engine, there are a number ofparameters controlled. E.g. when the engine isstopped, it is not valid to create alarms for coolingwater pressure. Therefore alarms need to besuppressed under certain conditions. WECS 8000has because of this and other reasons a number ofmodes. Different modes have different priority, andthe mode changes can occur only according to pre-defined rules.



General

Engine control processes during operation

WECS 8000 performs a number of continuous control processes on theengine, when the engine is in run mode. Below, a brief description ofeach of these processes.

Processes can be divided into categoriesEngine speed- and load controlGas pressure controlGas admissionDiesel actuatorPilot systemPilot injectionPilot pressure controlAir/fuel ratioCylinder balancing



Fig. name: Gas feed system layout

Gas feed system layout


The gas supplied to the engine passes at first a gasvalve unit (GVU). The gas valve unit consists of a filter,temperature/pressure sensors, a pressure regulatingvalve, safety (shut-off) valves and ventilation valves.The gas supply pressure reference is calculated in theWECS 8000 main control module, and this reference isdependent on the engine load. An electrical pressurereference signal is sent out to the pressure regulatingvalve. The actual gas pressure is measured on theengine and compared to the reference pressure.The amount of main gas admitted to each cylinder iscontrolled by the cylinder individual gas valves, whichare actuated by the cylinder control modules. Theamount of gas admitted depends on the gas supplypressure and the time the main gas solenoid valve isopen (duration). The gas fuel is admitted further awayor closer to the TDC by changing the main gassolenoid valve opening moment (timing) in order toobtain an optimal air/gas mixture. The WECS 8000system uses pre-set (map) values to optimise thismixture during engine operation. Valve duration andtiming references are sent to the cylinder controlmodules from the main control module over the CAN-bus.




Fig. name: Cylinder control and measurement

Cylinder control and measurementsAn even gas admission duration setting for all gasadmission valves will not result in exactly the samegas quantity in all cylinders, due to the geometry ofthe engine and due to some deviations in the gasvalve performance. This slight disparity is handledwith the cylinder balancing control.

System components01 Main gas admission valve02 Diesel injector with pilot valve03 Pilot fuel pump04 Knock sensor05 Exhaust gas temperature sensor06 Cylinder liner temperature sensor




Fig. name: Cylinder control and measurement

Cylinder control and measurementsThe main control module compares each cylinder’sexhaust gas temperature with the average exhaustgas temperature of the entire engine, and adjusts theduration of the individual gas valves with an offset, inorder to minimise the deviation. There are limitationsfor the maximum adjustment available in order toprevent that possible component failures cause a toorich or too lean gas/air mixture.The knock control algorithm of WECS 8000 will alsoaffect the gas admission duration.If the engine is in gas operating mode, and the loadlevel is above approximately 15 % (tuneable) acylinder knock based control will enable. Light knockin any cylinder will immediately result in a slightreduction of the quantity of gas injected into thatcylinder. In order to maintain the same engine loadlevel, the speed/load controller will automaticallyincrease the gas admission into other cylinders.When the situation normalises in the cylinder, the gasadmission will slowly be restored to the originalsetting .



Fig. name: Gas/pilot valve, PWM output voltage

Gas/pilot valve PWM control

Gas/pilot valve control strategy:110 VDC drive voltage ensures high energy atvalve opening.The PWM drive signal has envelop shaping to

provide fast & consistent valve opening but alsolow heat generation in the coil.The pull-in and hold-in current levels are s.w.configurable.




Fig. name: Gas/pilot valve, PWM current characteristics

Gas/pilot valve PWM control

Gas/pilot valve control strategy:110 VDC drive voltage ensures high energy atvalve opening.The PWM drive signal has envelop shaping to

provide fast & consistent valve opening but alsolow heat generation in the coil.The pull-in and hold-in current levels are s.w.configurable.


01_ Automation for W50DF

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