Optimal & Predictive Energy Management for hybrid
electric vehicles
Dr. M.Sans, Dr. J.Lachaize, D.Verdier
CESEC Summer School 2014
Powertrain division
Agenda
1 Hybrid Vehicle system description
2 Hybrid Vehicle energy management
3 Hybrid components supervision
4 Hybrid Vehicle Functional safety
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
2
Hybrid vehicle architecture
Definition
P1
Front
P0
P0 =
Rear
P2
P3
P4
P1 =
P2 =
P3 =
P4 =
C1
C0
Belt Startergenerator
Starter-generator on
the crankshaft
E-Machine after the
engine clutch
E-Machine in the
gearbox or on the
differential
E-Machine on rear
axle
C0, C1 = Clutch
(Source : Daimler)
Continental Automotive, Powertrain Division
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Hybrid vehicle architecture
Electrical architecture
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
4
Agenda
1 Hybrid Vehicle system description
2 Hybrid Vehicle energy management
3 Hybrid components supervision
4 Hybrid Vehicle Functional safety
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
5
Optimal & Predictive Energy Management for HEV
Power distribution
Traction Power Control of Parallel Architectures:
(1-α)
(α)
+
Power to Wheels
= sum of 2 Powers
from ICE
and from Elect Mot
Question is to calculate the Torque Distribution Factor (α)
to get Optimal conditions: maximizing the efficiencies
or minimizing the total losses
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
6
Optimal & Predictive Energy Management for HEV
Power distribution
Traction Power Control of Parallel Architectures:
(1-α)
(α)
+
Power to Wheels
= sum of 2 Powers
from ICE
and from Elect Mot
1) by optimization of instantaneous Power at current time (to)
or
2) by optimization of global Energy on a Time Horizon [ to…to+H ]
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
7
Optimal & Predictive Energy Management for HEV
Power distribution
›
Polynomial Identification of Power Losses:
5
2.8
Total losses for Speed = 130 km/h
x 10 W
gear
gear
gear
gear
gear
gear
2.7
dLosses
= 3 * p 3 * α 2 + 2 * p 2 * α + p1
dα
2.6
Extremum :
2.5
dL
2
= 0 => ∆ ' = p 2 − 3 * p 3 * p1
dα
=
=
=
=
=
=
1
2
3
4
5
6
2.4
2.3
Optimal α is = 0.62, at gear=4
2.2
2.1
0
0.1
0.2
0.3
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0.4
0.5
alfa
0.6
0.7
0.8
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
0.9
1
8
Optimal & Predictive Energy Management for HEV
Power distribution
Test of a plug-in HEV
on NEDC test cycle
Cons= 377g of fuel
= 108 gCO2/km
∆SOC = -3% @ 50%
Computed test result
(based on official test
procedure) :
CO2 = 33.7 gCO2/km
(real Test = 31 gCO2/km)
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
9
Optimal & Predictive Energy Management for HEV
Power Prediction
Predictive Control :
what is the optimal alfa(t) ( and gear(t) )
providing the minimum SUM of Losses on the horizon [to, to+H] ?
Alfa_opti(H) ≠ “sum” of each alfa_opti(tk)
Alfa_opti(H) = alfa(t) as {Sum of Losses(t) } is minimal
Predicted speed
Alfa(t)
Alfa(t) = constant
ENERGY Losses
to
tk
Horizon H
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
10
Optimal & Predictive Energy Management for HEV
Power Prediction
Speed Prediction from a Kalman Filter :
limits of this approach : errors in extrapolations
60
Prediction at an horizon of 4 sec
50
40
30
20
10
0
200
220
240
260
280
300
320
340
360
380
Need for additional data for better anticipation : use of e-Horizon
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
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Optimal & Predictive Energy Management for HEV
Connected Powertrain
eHorizon provides information
from GPS localization
on environment context
and next future driving conditions
around and in front of the vehicle :
Continental Automotive, Powertrain Division
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September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
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Optimal & Predictive Energy Management for HEV
Connected Powertrain
Save CO2 by reducing “Passive States”:
Enlarge Coasting
Detect eBoost and Recuperation situations
Reduce unnecessary Charging Modes
to improve efficiency of ICE
Without prediction
With prediction
Coasting
Speed [kph]
Speed [kph]
System Passive
Recuperation
Traction Mode
Crossing detection
Time [s]
Time [s]
Based on Regensburg city real cycle basic - depending on occurring driving situations
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
13
Agenda
1 Hybrid Vehicle system description
2 Hybrid Vehicle energy management
3 Hybrid components supervision
4 Hybrid Vehicle Functional safety
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
14
Hybrid Vehicle Electric Power Management
Traction battery operating voltage and current limits
Lithium-ion battery abuse
usage consequences
http://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems
Temperature (°C)
Life time decreases
45
Temperature (°C)
Life time decreases
45
Safe
Operating
Area
Safe
Operating
Area
-25
-25
2
3
4.2
Voltage (V)
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-200
0
275
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
Current (A)
15
Hybrid Vehicle Electric Power Management
Maximum battery charging \ discharging current prediction
Cell voltage limit imply battery
current limitation
Cell voltage modelling
Predicted current
Ohmic effect
Polarization effect
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
16
Hybrid Vehicle Electric Power Management
Smart power distribution to protect traction battery
›
Traction battery is directly plug to electrical machine
Traction Battery
Current
›
DC\DC
Aux
Battery protection need
Smart electric power control
EM
Torque
Electrical machine torque limits determination
A
V
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
17
Hybrid Vehicle Electric Power Management
High voltage ↔ Low voltage control node constrains
Traction battery
Design for
vehicle range
›
12V battery
Design for
network stability
Low voltage network constrains to high voltage network
12V network must be kept in safe range
›
High voltage network constrains to low voltage network
12V supply could be limited due to li-ion battery limit
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
18
Agenda
1 Hybrid Vehicle system description
2 Hybrid Vehicle energy management
3 Hybrid components supervision
4 Hybrid Vehicle Functional safety
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
19
Hybrid vehicle safety
Hazard and risk
Objective : identify and rank risks related to new functions/components
› Vehicle take off in opposite
direction
HV Net
Front
› Loss of control due to
excessive regenerative
braking
Rear
› Unexpected acceleration
› Unexpected vehicle movement
E
M
BAT.
› Fire event
› Passenger intoxication
› Loss of vehicle control due to
loss of power on Aux network
› Loss of vehicle control due to
overvoltage on Aux network
DC\DC
Aux. Net
› Electric shock to car users
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
20
Hybrid vehicle safety
Architectural assignments
Objective : minimize development effort by performing the right safety requirements
allocations
Battery protection
Safety requirements for “passenger intoxication” :
› Battery cells shall not emit chemicals (venting)
when tested according to IEC62660, Chapter 6.
› Battery system shall not emit chemicals when
tested according to ISO 12405, Chapter 9.
› Design of the ventilation of the battery case
(under the OEM responsibility) shall be directed
to outside of the passenger compartment in
order to control the risk.
No additional safety requirements for
“Passenger intoxication
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
21
Hybrid vehicle safety
Technical safety concept
Objective : Define technical measures that are required to satisfy a safety goal
VDA E-Gaz 3 levels concept
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
22
Hybrid vehicle safety
Technical safety concept
Engine
torque
estimation
Driver
Realized
Torque
Torque
compare
Torque
demand
Electrical
machine
torque
Braking
Cruise
control
Safety
reaction
Perform safety reaction if Realized torque >> Demanded Torque
Continental Automotive, Powertrain Division
Confidential
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
23
Optimal & Predictive Energy Management for HEVs
Conclusion
Power Distribution is a new control parameter in
HEVs
Target : Optimization of Efficiencies (or losses)
Based on instantaneous
Power
Map based
using Analytic
equations
Based on Predicted
Energy
using internal
prediction
filters
(Kalman…)
Continental Automotive, Powertrain Division
Confidential
Compliant
with
Physical
Limits &
Safety
Constraints
using external
information
from GPS
and eHorizon
September 9th, 2014
Lachaize, Sans, Verdier © Continental AG
24
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