Control Engineering with a Transient Model of a Fuel Cell Coolant ...

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Control Engineering with a Transient Model of a Fuel Cell Coolant ...

Control Engineering

with a Transient Model of a Fuel Cell Coolant Loop in GT-Suite

R. Höß (Fuel Cell Cooling System, Daimler AG)

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012

1


Control Engineering

with a Transient Model of a Fuel Cell Coolant Loop in GT-Suite

Agenda

1. Context - Fuel Cell Car-Development at Daimler

2. Introduction - Cooling System for Fuel Cell Cars

3. Modelling

4. Model Verification

5. 3 Concepts of a Main Fan Controller

6. Simulation and Results

7. Conclusion and Achivements

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 2


Context (1)

Fuel Cell Car Development at Daimler in Nabern

Fuel Cell Powertrain Development

Kirchheim u.T. (Nabern)

Fuel Cell System Development

Kirchheim u.T. (Nabern)

Fuel Cell Stack Development

Vancouver, Canada

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 3


Context (2)

The Current Generation of Fuel Cell Vehicle

Technical Data

Vehicle Mercedes-Benz B-Class

Fuel Cell

System

Engine

PEM, 90 kW (122 hp)

Output (Cont./ Peak) 70kW / 100kW (136 hp)

Max. Torque: 290 Nm

Fuel Compressed hydrogen (70 MPa)

Range 380 km (NEDC)

Top Speed 170 km/h

Li-Ion Battery

Output (Cont./ Peak): 24 kW / 30 kW (40 hp)

Capacity: 6.8 Ah, 1.4 kWh

• Freeze Start Capability

• Emissions-free (CO 2 )

• Short refueling time and high range

with 70 MPa hydrogen storage

• Silent operation

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 4


Context (3)

B-Class F-CELL World Drive 2011

• 125 days

• 14 countries

• approx 19000 miles

• Route defined through

Scouting

• Convoy with 24 vehicles

• over 50 people

• 2 fueling Stops per day

• 174/155 miles until fueling

stop

• First world tour with fuel cell electric vehicles

• Demonstration of the technical maturity and performance of fuel cell technology

• Demonstration of a daily use of the fuel cell technology in different climate zones

• Appeal to all involved partners to push the development of H 2 -Infrastructure

For future fuel cell vehicle generations, further drive system cost reduction is intended

e. g. by simplification of the fuel cell system architecture

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 5


Introduction

Cost Reduction by Developing a New Main Fan Control Strategy Using GT-Suite

Challenges

▸ For a stable water management and efficient operation of the fuel cell stack, the coolant set temperature

and coolant massflow on the fuel cell has to be controlled precisely.

▸ The Controller for the thermostatic control valve and the controller for the main-radiator fan use the same

set point: FC-Stack coolant inlet temperature

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 6


Modelling (1)

Basic Model of the Coolant Hydraulics and Radiators Air Path

High Temperature Coolant Loop

Low Temperature Coolant Loop

▸ Starting Point was a basic model of the coolant loops and air-paths used for hydraulic balancing and cooling performance

evaluations.

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 7


Modelling (2)

Extension Step 1: Controller Functions of the coolant loops and transient verification

Temp. Control Valve

(Switch Characteristics)

Main Fan

(Speed)

Wheelhouse Fan

(Speed)

HT-Coolant Pump (Speed)

LT-Coolant Pump (Speed)

Off Valves

(Speed)

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 8


Modelling (3)

Extension Step 2: Fuel Cell System, Powertrain & Vehicle Environment

Cooling System

Vehicle &

Transmission

Hybridisation Strategy &

Battery

Fuel Cell System

Cooling Control Unit

▸ By adding a simplified, map-based powertrain model a transient vehicle model is achieved .

▸ Track profiles and cooling controller reactions can be calculated.

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 9


Model Verification (1)

Test-Drive (0-80km/h, trailer dynamometer): Stack-Performance

▸ The simulation results show a good correlation to the vehicle measurements for the stack performance.

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 10


Model Verification (2)

Test-Drive (0-80km/h, trailer dynamometer): FC Coolant Inlet-Temp., Fan Speed

▸ The simulation results show a good correlation to the vehicle measurements for the coolant set-point and the fan-speed.

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 11


Main Fan Controller Concept 1

applied in todays Fuel Cell propulsed B-Class



Map based pilot control of the temperature deviation.


Temperaturedifference on the radiator as set point, representing the cooling performance

on the radiator package.

(+) Robust control concept

(-) Two additional temperature sensors needed on the coolant-inlet and outlet of the radiators

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 12


Main Fan Controller Concept 2:

PID-Controller, Stack Coolant Inlet Temperature as Reference



Map based pilot control of the temperature deviation.

PID-Controller (Stack Coolant Inlettemperature)

(+) Standard Control Concept

(-) Same control reference as the Thermostatic Valve – Interference expected.

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 13


Main Fan Controller Concept 3

Model based Control

System Waste Heat Model:

• Stack Current

• Stack Voltage

Cooling Performance Model:

• Vehicle Speed

• Ambient Temp.

• AC Condensation Pressure

• Pump Speed

• LT-Coolanttemp.

• T-Set_KW1_STM

• T_KW1_STM

• T_KW2_STM



Map based pilot control of the temperature deviation.


Modelbased Fan Control, based on the calculation of the FCS-powertrain - and cooling

performance.

(+) Precise fan control on cooling requirement, similar to Concept 1.

(-) Higer setup and programming effort, higher cpu and memory usage on control unit

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 14


Simulation

Comparison of the Main Fan Controller Concepts

Concept 1

Predecessor Concept

Concept 2

PID-Controller

Concept 3

Model Based Control

Temperature Overshoot

(mean value of drive cycle)

[K]

Total Rejected Heat

[MJ]

Fan Power Consumption

[kJ]

Fan Controller Efficiency

(rejected heat per fans power

consumption in drive cycle)

[-]

Concept 1 3.07923 31.797255 340.04145 93.5

Concept 2 4.71665 30.188025 63.56364 474.9

Concept 3 2.89629 31.902255 377.8782 84.4

▸ The model-based controller concept shows the best potential to fullfill the requirements to precisely control the fuel cell

temperature setpoint and to have a efficient cooling system and achive the cost potential of eleminating 2 temp-sensors.

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 15


Conclusion and Achivements

Control Engineering with GT-Suite

Modelling and Simulation

• Successful setup and simulation of a fastrunning fuel cell vehiclemodell within GT-Suite.

• Approved correlation of the simulation model even on vehicle-level with simulated drive-cycles.

• But the verified transient behavior especially of the coolant loop is essential.

Control Engineering

• Evaluation of controller concepts regarding effectivity and efficiency with this model.

Controller response can be optimised in detail.

• Maturity of control unit software can be raised especially in early software cycles.

• Test drive efforts for software development can be reduced.

• Elemination of 2 temperature sensors seem to be achivable.

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Conference | 22.10.2012 16


Thanks for your attention!

For further information please visit:

www.daimler.com/technologie-und-innovation/antriebe/elektrische-antriebe/brennstoffzelle

R. Höß (Fuel Cell Cooling System, Daimler AG) | GT-Confefence | 22.10.2012 17

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