Regenerative Braking Algorithm For a HEV with CVT
Ratio Control During Deceleration
Hoon Yeo, Donghyun Kim, Sungho Hwang, Hyunsoo
Kim Sungkyunkwan University
Dynamic System Design & Control Lab.Sungkyunkwan University
2
Motor
Battery
+ -
Transmission
IC Engine
Regenerative Braking
Generator
Introduction
3
EPA75
Urban
Austr.Urban
ECE-15Japan1015
NewYorkCity
Traction energyKJ
Total4000 6480 3478 1675 998
Perkm.
377 606 437 402 519
Braking energyKJ
Total 1934 4195 953 888 878
Perkm.
182 392 120 213 461
Percentage of braking energy to total traction energy (%)
48.3 64.7 27.5 53.0 88.8
Traction and Braking Energy Consumption
4
the regenerative braking force is not large enough to
cover the required braking force the regenerative braking can not be used for many
reasons such as high state of charge or high
temperature of the battery to increase the battery life
REGENBRAKING
FRICTIONBRAKING+
5
Develop a regenerative braking control algorithm
Develop a prototype electro-hydraulic controlled
regenerative braking module
Propose a CVT ratio control algorithm to obtain maximum
regenerative energy during deceleration
Objectives
6
Hybrid Electric Vehicle
+ -Battery
Engine
Motor &Generator
InverterREGEN
Hydraulic Module
REGENHydraulic Module
Pedal
BCUBCU
MCUMCU
HEV-ECUHEV-ECU
7
Master cylinder
BCU
PP
Motor
Pump
Accumulator
Proportional
reducing valve
PP
HEV - ECU
sON_OFF switch
Relief valve
PHPL
Stroke simulator
Vacuum
booster
Front wheel cylinder Rear wheel cylinder
Powerpack
Regenerative Braking Hydraulic Module
8
Regenerative Braking Algorithm
REG
R
TNiT
•
•
1W 2W
Regenerative torque applied to the front wheel
1W
2W
1W (SOC)
2W (Velocity)
9
SOC, %
0
0.5
1
0 20 40 60 80 100
Wei
ght
fact
or, W
1W
eigh
t fa
ctor
, W2
VelocityV1 V2
1
Weight Factor for Regenerative Braking
10
Regenerative Braking Algorithm
Ff HYD = Fbf – FREGEN
b
fHYDtf ra
FRP
2
Regenerative braking force
Hydraulic braking force required at the front wheel
Front wheel cylinder pressure equivalent to FfHYD
RTREGENF
tR
11
Braking Forces on the Front and Rear Wheel
Rea
r br
ake
forc
e
Front brake force
P
brF
bfFRICTIONFREGENF
bfF
12
Pedal input
Rear pressure
Ideal distribution of braking force
Battery SOC,Velocity,
CVT ratio
Rear braking force
Front braking force, Fbf
Regenerative torque,TREGEN
Regenerative force FREGEN
21RT WWiNTREGEN
Fbf > FREGENNoYes
PF = 0
Regenerative braking+
Friction braking
Hydraulic module
Regenerative braking
Fbf = FREGEN
Friction braking
FbfFRICTION=Fbf-FREGEN
b
bfFRICTIONtf
rA
FRp 2
bfFRICTIONF
Flow Chart for Regenerative Braking
13
CVT Ratio Control
0 6000500040003000200010000
- 40
- 80
Motor speed, rpm
Mo
tor
torq
ue,
Nm
88%
86%
84%82%
80%
78%70%60%
OOL
Motor efficiency
14
CVT Ratio Control
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
500 1500 2500 3500 4500 5500
Demand braking torque
Wheel power
A
B
0
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
500 1500 2500 3500 4500 5500
Demand braking torque
Wheel power
A
B
60000 30000
- 80
Mo
tor
torq
ue
, N
m OOL
Motor speed, rpm
- 50
Optimal operating line in regenerative braking
15
CVT Ratio ControlFlow chart of CVT ratio control
Brake=on?NoYes
Motor optimal operation
Desired CVT ratio
Engine optimal operation
Calculate wheel power
Calculate desired speedω gen_desired from OOL
Pedal input
f
tdmd NV
Ri
)
16
HEV Powertrain Model
17
Engine Stroke volume
Maximum torque
1600cc
140Nm
Motor 10kW Motor torque at base rpm 50Nm
Vehicle
CVT gear ratio range
Final reduction gear ratio
Vehicle mass
Front project area
Drag coefficient
Tire radius
0.455 ~ 2.47
5.763
1380 kg
1.964 m2
0.346
0.279 m
Vehicle Data
18
Simulation Results
A
Pre
ssu
re,
bar
0
30
CVT REGEN(rear)
REGEN(rear)
REGEN(front)
CVT REGEN(front)
(d)
(e)
19
Simulation Results
Motor speed, rpm
Mo
tor
torq
ue,
Nm
-100
-50
0
50
100
0 1000 2000 3000 4000 5000
CVT REGEN
REGEN
(f)
OOL
20
Motor Operation Trajectories for FUDS
Motor speed, rpm
Mo
tor
torq
ue
, Nm
-100
-50
0
50
100
0 1000 2000 3000 4000 5000 6000
OOL
-100
-50
0
50
100
0 1000 2000 3000 4000 5000 6000
Mo
tor
torq
ue,
Nm
CVT REGEN
REGEN
Simulation Results
21
Simulation Results
95
100
105
%
Battery SOCFuel Economy
CVT REGEN
REGEN
Comparison of fuel economy and final battery SOC for FUDS
22
Regenerative braking algorithm is proposed.
Prototype electro-hydraulic regenerative braking
module is developed.
CVT ratio control algorithm during deceleration is
suggested.
Fuel economy is improved by 4 percent for FUDS
Conclusion