This paper presents the influence on fuel consumption of two auxiliaries for two different topologies.

1. Introduction Modeling of auxiliaries units Conclusions
Modeling for Control and Optimal Design of a
Power Steering Pump and an Air Conditioning
Compressor used in Heavy Duty Trucks
E. Silva¸s, O. Turan, T. Hofman and M. Steinbuch
Dept. of Mechanical Engineering, Eindhoven University of Technology
9th Vehicle Power and Propulsion Conference,
Octomber 15-18, 2013, Beijing, China
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

2. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Motivation
How can the fuel consumption be reduced in future hybrid trucks?
"Belt driven auxiliary units can consume up to 15% of the total
power for a truck and up to 25% for a transit bus..."
Auxiliary Units
Power Steering Pump (PSP)
Water Pump (WAP)
Air Brake Compressor (ABC)
Engine Cooling Fan (ECF)
Alternator (ALT)
Air Cond. Compressor (ACC)
Starter Motor (STM)
Oil Pump (OLP)
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

3. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Motivation
How can the fuel consumption be reduced in future hybrid trucks?
"Belt driven auxiliary units can consume up to 15% of the total
power for a truck and up to 25% for a transit bus..."
Auxiliary Units
Power Steering Pump (PSP)
Water Pump (WAP)
Air Brake Compressor (ABC)
Engine Cooling Fan (ECF)
Alternator (ALT)
Air Cond. Compressor (ACC)
Starter Motor (STM)
Oil Pump (OLP)
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

4. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Motivation
How can the fuel consumption be reduced in future hybrid trucks?
"Belt driven auxiliary units can consume up to 15% of the total
power for a truck and up to 25% for a transit bus..."
Auxiliary Units
Power Steering Pump (PSP)
Water Pump (WAP)
Air Brake Compressor (ABC)
Engine Cooling Fan (ECF)
Alternator (ALT)
Air Cond. Compressor (ACC)
Starter Motor (STM)
Oil Pump (OLP)
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

5. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Motivation
How can the fuel consumption be reduced in future hybrid trucks?
"Belt driven auxiliary units can consume up to 15% of the total
power for a truck and up to 25% for a transit bus..."
Auxiliary Units
Power Steering Pump (PSP)
Water Pump (WAP)
Air Brake Compressor (ABC)
Engine Cooling Fan (ECF)
Alternator (ALT)
Air Cond. Compressor (ACC)
Starter Motor (STM)
Oil Pump (OLP)
Engine Cooling Fan
Water Pump
Air Brake
Compressor
Air Brake
Compressor
Steering Pump
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

6. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Motivation
How can the fuel consumption be reduced in future hybrid trucks?
"Belt driven auxiliary units can consume up to 15% of the total
power for a truck and up to 25% for a transit bus..."
Auxiliary Units
Air Conditioning
Compressor
Power Steering Pump (PSP)
Water Pump (WAP)
Air Brake Compressor (ABC)
Engine Cooling Fan (ECF)
Alternator (ALT)
Air Cond. Compressor (ACC)
Starter Motor (STM)
Oil Pump (OLP) Fuel Pump
Starter Motor
Alternator
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

7. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Motivation
Conventional (non-hybrid) vehicles topology:
Fuel tank Engine
Transmission
Final drive + wheels
Mechanical link
Hybrid Electric Truck (Parallel Topology):
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

8. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Motivation
Conventional (non-hybrid) vehicles topology:
Fuel tank Engine
Transmission
Final drive + wheels
Mechanical link
Hybrid Electric Truck (Parallel Topology):
BAT INV
ICE
EM
FTA TRA
WAP
FDW
COF
OLP
ALT
ABC
ACC
PSP
STM
Mechanical
Electrical
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

9. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Motivation
Literature findings on removed auxiliaries:
6
5
4
3
2
1
0
Percentage change in fuel economy [%]
All auxiliaries
removed
PSP
removed
COF
removed
ACC
removed
ABC
removed
ALT
removed
T. Hendricks and M. O0Keefe.Heavy vehicle auxiliary load electrification for the essential power system
program: Benefits, tradeoffs, and remaining challenges.In SAE Tehnical Paper Series, 2002.
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

10. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Project Goal
Analyse the benefits and trade-offs of
electrification for Steering Pump and Air
Conditioning Compressor by
Modeling and validation of
auxiliaries units,
Validation of the fuel consumption
values with literature,
Analysis of possible topologies/
controllers.
BAT INV
ICE
EM
FTA TRA
WAP
FDW
COF
OLP
ALT
ABC
ACC
PSP
STM
Mechanical
Electrical
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

11. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Project Goal
Analyse the benefits and trade-offs of
electrification for Steering Pump and Air
Conditioning Compressor by
Modeling and validation of
auxiliaries units,
Validation of the fuel consumption
values with literature,
Analysis of possible topologies/
controllers.
BAT INV
ICE
EM
FTA TRA
WAP
FDW
COF
OLP
ALT
ABC
ACC
PSP
STM
Mechanical
Electrical
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

12. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Project Goal
Analyse the benefits and trade-offs of
electrification for Steering Pump and Air
Conditioning Compressor by
Modeling and validation of
auxiliaries units,
Validation of the fuel consumption
values with literature,
Analysis of possible topologies/
controllers.
BAT INV
ICE
EM
FTA TRA
WAP
FDW
COF
OLP
ALT
ABC
ACC
PSP
STM
Mechanical
Electrical
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

13. Introduction Modeling of auxiliaries units Conclusions
Optimal Design on Hybrid Vehicles
Project Goal
Analyse the benefits and trade-offs of
electrification for Steering Pump and Air
Conditioning Compressor by
Modeling and validation of
auxiliaries units,
Validation of the fuel consumption
values with literature,
Analysis of possible topologies/
controllers.
BAT INV
ICE
EM
FTA TRA
WAP
FDW
COF
OLP
ALT
ABC
ACC
PSP
STM
Mechanical
Electrical
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

14. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
PSP System
Steering
Wheel
s 
Steering
Angle
Pinion Shalft
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

15. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
PSP System
Steering
Wheel
s 
Steering
Angle
Pinion Shalft
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

16. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
PSP System
Left hand
tube for
left hand
Power Steering
Pump
Rotary Valve
Body Unit
Reservoir
Steering
Wheel
s 
Steering
Angle
Steering
Gearbox and
Hydraulic Piston
Belt to
the ICE
Rack
turn
Pinion Shalft
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

17. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
PSP System
Left hand
tube for
left hand
Power Steering
Pump
Rotary Valve
Body Unit
Reservoir
Steering
Wheel
s 
Steering
Angle
Steering
Gearbox and
Hydraulic Piston
Belt to
the ICE
Rack
turn
Pinion Shalft
Energy
saving
potential
Hydraulic output power
Power [-]
 ,max Pump Shaft Speed [-] Q
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

18. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
Experimental Data
1
0.8
0.6
0.4
0.2
0
-1 0 1 2 3 4
Steering Angle [rad]
Power Steering Pressure [-]
Active Steering Region
Pressure Drop Region
Passive Steering Region
Assumptions /Constraints:
s 2 [0:5; 0:5] rad is considered road disturbance,
s = 0:1 rad is the symmetry point.
PSP Model I/O:
u(t) =
s
sign(_
s)
y(t) =
Pp
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

19. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
Experimental Data
1
0.8
0.6
0.4
0.2
0
-1 0 1 2 3 4
Steering Angle [rad]
Power Steering Pressure [-]
Active Steering Region
Pressure Drop Region
Passive Steering Region
Assumptions /Constraints:
s 2 [0:5; 0:5] rad is considered road disturbance,
s = 0:1 rad is the symmetry point.
PSP Model I/O:
u(t) =
s
sign(_
s)
y(t) =
Pp
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

20. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
Experimental Data
1
0.8
0.6
0.4
0.2
0
-1 0 1 2 3 4
Steering Angle [rad]
Power Steering Pressure [-]
Active Steering Region
Pressure Drop Region
Passive Steering Region
Assumptions /Constraints:
s 2 [0:5; 0:5] rad is considered road disturbance,
s = 0:1 rad is the symmetry point.
Steering
Pump
u(t) y(t)
PSP Model I/O:
u(t) =
s
sign(_
s)
y(t) =
Pp
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

21. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
Modeling Validation
Sequential Modeling
Measurements from 8
different driving cycles
^Pp = As + B2
s + C
min() =
PNi
=1
q
(Ppi ^Ppi )2;
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
s:t: 0 C 15 -10 -8 -6 -4 -2 0 2 4 6 8 10
Steering Angle [rad]
Pressure [-]
Validation
Route: Oss - Eindhoven
Energy cons. error =
1.7%
Improvement: steering
velocity
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

22. Introduction Modeling of auxiliaries units Conclusions
Power Steering Pump
Modeling Validation
Sequential Modeling
Measurements from 8
different driving cycles
^Pp = As + B2
s + C
min() =
PNi
=1
q
(Ppi ^Ppi )2;
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
s:t: 0 C 15 -10 -8 -6 -4 -2 0 2 4 6 8 10
Steering Angle [rad]
Pressure [-]
Validation
Route: Oss - Eindhoven
Energy cons. error =
1.7%
Improvement: steering
velocity
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

23. Introduction Modeling of auxiliaries units Conclusions
Air Conditioning Compressor
ACC System
Compressor
Condenser Evaporator
Receiver+Valve
Cab
Interior
Low Pressure Vapour
Heater
core
Warm Ambient Air Cold Air Conditioned Air
Low Pressure Liquid
High Pressure Vapour
Blower
Cooling fan
Ambient Air
Hot Air
High Pressure Liquid
Cooling functionality is carried
out by the evaporator:
u(t) =
2
664
m_ a
Rh
Ta
Tc
3
775
y(t) =
2
4
Te
Pc
c
3
5
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

24. Introduction Modeling of auxiliaries units Conclusions
Air Conditioning Compressor
ACC System
Compressor
Condenser Evaporator
Receiver+Valve
Cab
Interior
Low Pressure Vapour
Heater
core
Warm Ambient Air Cold Air Conditioned Air
Low Pressure Liquid
High Pressure Vapour
Blower
Cooling fan
Ambient Air
Hot Air
High Pressure Liquid
u(t) Evaporator y(t)
Cooling functionality is carried
out by the evaporator:
u(t) =
2
664
m_ a
Rh
Ta
Tc
3
775
y(t) =
2
4
Te
Pc
c
3
5
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

25. Introduction Modeling of auxiliaries units Conclusions
Air Conditioning Compressor
Modeling
u(t) Evaporator y(t)
Cooling functionality is carried
out by the evaporator:
u(t) =
2
664
m_ a
Rh
Ta
Tc
3
775
y(t) =
2
4
Te
Pc
c
3
5
Depending on the compressor operation:
Two modes defined 8 Te 2 [Te;min; Te;max]
m1 ! (C = 1) ^ T_e = Ql+QaQe
Ce
;
m2 ! (C = 0) ^ T_e = Qa
Ce
;
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

26. Introduction Modeling of auxiliaries units Conclusions
Air Conditioning Compressor
Comparison with literature findings:
6
5
4
3
2
1
0
Percentage change in fuel economy [%]
All auxiliaries
removed
PSP
removed
ACC
removed
COF
removed
Payload 50%
Study case from literature
ALT
removed
ABC
removed
T. Hendricks and M. O0Keefe.Heavy vehicle auxiliary load electrification for the essential power system
program: Benefits, tradeoffs, and remaining challenges.In SAE Tehnical Paper Series, 2002.
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

27. Introduction Modeling of auxiliaries units Conclusions
PSP Control Algorithm
Variable Flow Control
Variable flow
rate control
Steering
system
s 
h T
p P
 Q
e P
r P
For Qh 2 f10; 12; 14; 16g :
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

28. Introduction Modeling of auxiliaries units Conclusions
Conclusions
Summary
Electrified auxiliaries enable Start/Stop and Zero Emission
Driving;
The electrification of the PSP and of the ACC brings
significant improvements in fuel consumption;
Variable flow control decreases the fuel consumption of the
PSP with approx. 50%
Future work
Develop improved control algorithms at unit level;
Synthesize a supervisory optimal controller for the
auxiliaries (integrated with the topology/techonology
selection).
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

29. Introduction Modeling of auxiliaries units Conclusions
Conclusions
Summary
Electrified auxiliaries enable Start/Stop and Zero Emission
Driving;
The electrification of the PSP and of the ACC brings
significant improvements in fuel consumption;
Variable flow control decreases the fuel consumption of the
PSP with approx. 50%
Future work
Develop improved control algorithms at unit level;
Synthesize a supervisory optimal controller for the
auxiliaries (integrated with the topology/techonology
selection).
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units

30. Introduction Modeling of auxiliaries units Conclusions
Conclusions
Thank you!
Emilia Silva¸s (e.silvas@tue.nl) Electrification of Auxiliaries Units