Transcript Battery – Electrochemical Capacitor Energy Storage for

Alternative Energy Storage System
for Hybrid Electric Vehicles
Tobias Andersson, Jens Groot,
Helena Berg, Joachim Lindström, Torbjörn Thiringer
1
Purpose and Method
• Hybrid electric vehicle: demands on an efficient
energy storage system
2
Energy Storage
• Energy- and power density
3
Supercapacitor
A.k.a Electrochemical Double Layer Capacitor (EDLC), Ultracapacitor,
Electrochemical Capacitor (EC)
• Extremely high capacitance (kF)
• Low voltage (< 3 V)
 1000-2000m2/kg
C
A
 10-100 F/g
d
5Å
4
Battery - Supercapacitor
5
Simulation of the system
6
Performance Parameters
• Reducing of RMS-current
• Reducing of power losses in
battery
• Total energy efficiency
7
Load Cycle (ECE15-L)
10
5
• Acceleration
0
• Constant velocity
-5
P[W/kg]
-10
• Regenerative braking
-15
-20
-25
0
20
40
60
80
100
120
140
160
180
200
t[s]
8
Control Strategy
2000
• Low pass filtering
1000
0
• Braking energy to EC
P[W] -1000
• Loading of EC
-2000
-3000
EC Power
Load Power
Battery Power
-4000
0
10
20
30
40
50
60
70
80
90
100
t[s]
9
Control Strategy
2000
• Low pass filtering
1000
0
• Braking energy to EC
P[W] -1000
• Loading of EC
-2000
-3000
EC Power
Load Power
Battery Power
-4000
0
10
20
30
40
50
60
70
80
90
100
t[s]
10
Test System
11
Test System
• EC
10 units 2.5V, 2600F /
28 units 2.0V, 2700F
• Battery
50V / 100V, 60Ah
NiMH
• DC/DC
160 kW, 330A
2-quadrants DC/DC
converter
12
Results
- simulations and experiment
4000
• Battery, 100V
Load Power Sim.
Load Power Exp.
Battery Power Exp.
Battery Power Sim.
3000
2000
1000
• EC, 56V
0
P[W] -1000
• Equal to car
with the weight
of 250 kg
-2000
-3000
-4000
-5000
-6000
0
20
40
60
80
100
120
140
160
180
t[s]
13
Results
- system performance
Performance Parameters Experiment
RMS battery current
56
Power losses i battery
26
Total energy efficiency
95
Simulation
55
27
94
Unit
% of reference case
% of reference case
%
14
Example
-Simplified system for a city bus, 220kW
NiMH-battery + EC
Battery
EC
DC/DC
310 kg
280 kg
90 kg
Total weight 680 kg
NiMH-battery
Battery
DC/DC
1150 kg
45 kg
Total weight 1195 kg
Weight reduction: 43 %
15
Conclusions
Drawbacks
Advantages
• Complexity
• Difficult to estimate
the price
• Not tested in full scale
• Weight reduction
• Improved battery lifetime
• Reduced temperature
dependency
• EC could replace batteries
16