This paper presents an overview of the
existing approaches and algorithms used for optimal design of hybrid electric vehicles (HEV). It also
includes an introduction in various hybrid topologies and examples from different transportation sectors.
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ECOSM Conference, Review of Optimal Design Strategies for HEV
1. Introduction Optimal design Conclusions
Review of Optimal Design Strategies
for Hybrid Electric Vehicles
Emilia Silva¸s, Theo Hofman and Maarten Steinbuch1
1Department of Mechanical Engineering
Eindhoven University of Technology
E-COSM, 23-25 October 2012, Rueil-Malmaison, France
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
2. Introduction Optimal design Conclusions
Optimization problem
Size
Control
Motorcycle
Vehicle
Truck
Crane
Ship
Airplane
Fuel
Emission
Performance
Comfort,
Handling
Cost
Topology
Application Parameters
Targets /
Constraints
(predicted) operation conditions
Technology
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
3. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 1: Size optimization
PHEV city bus
A parallel and a series topology
Battery size
Convex optimization vs. DP
Assumptions: gear and engine
on/off state
Error vs. no. of variable /
computation time
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
4. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 1: Size optimization
PHEV city bus
A parallel and a series topology
Battery size
Convex optimization vs. DP
Assumptions: gear and engine
on/off state
Error vs. no. of variable /
computation time
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
5. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 2: Size and technology optimization
Mid-sized to large family car (torque-assist)
Use, initially, DP to find the optimal driving strategy
Build a RB method - sizing of the CE, EM (8 driving cycles)
Minimize the CO2 emissions
Adjusted Gear Ratio
CO2 emissions, 1% for the RB method
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
6. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 3: Size and topology optimization
Submarine
4 sea mission scenarios
Multiobjective Genetic
Algorithms
Five objective functions
Max. propeller efficiency
Max. electric motor efficiency
Min. electric motor size
Min. total energy consumption
Max. steam turbine efficiency
8% improvement in energy
consumption
Electric
Motor
Electric
Motor
Electric
Motor
Gearbox
Steam
Turbine
Electric
Motor
Gearbox
(a)
(b)
(c)
Source: http://www.guardian.co.uk
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
7. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 3: Size and topology optimization
Submarine
4 sea mission scenarios
Multiobjective Genetic
Algorithms
Five objective functions
Max. propeller efficiency
Max. electric motor efficiency
Min. electric motor size
Min. total energy consumption
Max. steam turbine efficiency
8% improvement in energy
consumption
Electric
Motor
Electric
Motor
Electric
Motor
Gearbox
Steam
Turbine
Electric
Motor
Gearbox
(a)
(b)
(c)
Source: http://www.guardian.co.uk
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
8. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 3: Results
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
9. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 4: Size optimization
Mid-size Passenger Vehicle
Optimize a parallel HEV for
maximum fuel economy
Composite driving cycle
Compare for 4 algorithms
Engine
Motor/
Generator
Transmission
Electric Power
Controller
Battery
Electrical connection
Mechanical connection
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
10. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 4: Size optimization
Mid-size Passenger Vehicle
Optimize a parallel HEV for
maximum fuel economy
Composite driving cycle
Compare for 4 algorithms
HWFET (Highway Fuel
Economy Test)
FTP-75 (Federal Test Procedure)
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
11. Introduction Optimal design Conclusions
Parametric and structural design optimization
Example 4: Size optimization
Mid-size Passenger Vehicle
Optimize a parallel HEV for
maximum fuel economy
Composite driving cycle
Compare for 4 algorithms
Before
Opt. DIRECT
Simulated
Annealing
Genetic
Algorithms
Particle Swarm
Optimization Constraints:
Fuel Economy
[L/100km] 6,7 5,93 5,83 6,26 6,34
Vehicle Weight [kg] 1683 1635 1656 1694 1690
Power rating of the
EM [kW] 65,9 20,2 21,9 24,2 14,8 10 kW - 80 kW
Power rating of the
ICE [kW] 86 83,1 82,4 95,5 87,1
40 kW - 100
kW
0-60 mph [sec] 18,1 15,5 10,8 11,9 11,1 ≤ 18.1 s
40-60 mph [sec] 7 6,8 5 4,4 4,9 ≤ 7 s
0-85 mph [sec] 35,1 30,6 20,7 21,2 20 ≤ 35.1 s
Bat. No of cells 240 245 311 300 238 150-350
120%
100%
80%
60%
40%
20%
0%
Fuel Economy Vehicle Weight Power rating of
the EM
Power rating of
the ICE
0-60 mph 40-60 mph 0-85 mph Bat. No of cells
Percent Change
Before Opt. DIRECT Simulated Annealing (SA) Genetic Algorithms (GA) Particle Swarm Optimization (PSO)
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
12. Introduction Optimal design Conclusions
Parametric and structural design optimization
Challenges and trends in hybrid power-trains design
Challenges
Large design space
High computation time
Discrete/Continuous variables
Non-convexity character of the problem
Trends
Multi-objective optimization
More automated approaches in searching for the global
optimum
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
13. Introduction Optimal design Conclusions
Parametric and structural design optimization
Challenges and trends in hybrid power-trains design
Classification of the hybrid power train optimization algorithms
mostly used for optimal design
Global Deterministic
Dynamic
Programing
DIRECT
Genetic
algorithms
Derivative free
Multi-objective
Genetic
Algorithms
Particle Swarm
Optimization
Simulated
Aanealing
Sequential
Quadratic
Programing
Convex
optimization
(subgradient
)
Convex
optimization
(gradient)
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
14. Introduction Optimal design Conclusions
Conclusions
Summary
The optimum power train design is desired for fuel
consumption minimization, emissions and dynamic
performance.
The complexity of the design space makes the design
difficult.
Future work
Develop and analyze an optimization framework for
commercial vehicles under given work conditions.
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV
15. Introduction Optimal design Conclusions
Conclusions
Thank you!
E. Silva¸s (e.silvas@tue.nl) Review of Optimal Design Strategies for HEV