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EVS28KINTEX, Korea, May 3-6, 2015
Analysis of the Cooling Performance and
Characteristic Using Lithium-ion Battery for
Eco-friendly Vehicle
Taecheol JeongSsangyong Motor Company, 150-3, Chilgoe-dong, Pyeongtaek-si,
Gyeonggi-do, Korea, [email protected]
Table of Contents
2
1. Motivations
2. xEVs Battery Pack Cooling System Over View
3. Li-Ion Battery Module Discharging Test
4. Li-Ion Battery Pack Temp Profile Test
5. EV Temp Profile Test in Hot Chamber
6. Conclusion and Future Works
Battery Temperature affects vehicle:
- Performance, reliability, safety, life-cycle cost
3
1. Motivations
Temperature affects battery:
- Operation of the electrochemical system
- Round trip efficiency
- Charging acceptance (Regen / Quick Charging)
- Power and energy availability
- Safety and reliability
- Life and life-cycle cost
irreversible chemical reactions
permanent damage of the cell
Desired Operating
Temperature
electrolyte in the cell may
freeze internal resistance
increases
• Battery performance strongly depends on the temperature• Best performance of Li-Ion cells is reached in a very narrow temperature band• So, Battery thermal management system is needed.
Battery power in vehicle is a function of resistance and control limits
Source: ‘VOLTEC Battery System for Electric Vehicle with Extended Range’, 2011 SAE International, 2011-01-1373‘Electric Vehicle Battery Thermal Issues and Thermal Management Techniques’, 2011 SAE International, Alternative Refrigerant and system efficiency Symposium. NREL
4
Li-Ion Battery Resistance Increases with Decreasing TemperatureCapacity Decreases
• Power decreases with decrease in temperature • Impacts power capability of motor and
vehicle acceleration
• Useful energy from the battery decreases withdecrease in temperature
• Impacts driving range and performance of vehicle
Source: ‘Electric Vehicle Battery Thermal Issues and Thermal Management Techniques’, 2011 SAE International, Alternative Refrigerant and system efficiency Symposium. NREL
1. Motivations
2. xEVs Battery Pack Cooling System Over View
• Liquid vs Air Cooling
Liquid-Cooling Air-Cooling Remarks
Images
Advantages&
Disadvantages
Pack temp. uniform - thermally stableGood heat transport capacity Better thermal control Lower volume, Compact designNoise ↓Weight ↑ / Leakage potential Higher maintenanceHigher cost
Separate cooling loop not required Low mass of air and distribution system No leakage concern No electrical short due to fluid concernSimple design Lower cost / Easier maintenance Low heat transport capacity More temperature variation in pack Blower noise
Models of Mass
Production
GM Volt, Spark EV, Ford Focus,Tesla Model S, etc
Mitsubishi i-MiEVHKMC Ray EV, Sonata HEV, Fluence, Priusetc
5
• Oil-cooling case is cooler and reaches steady state much more quickly• Liquid cooling/heating is more effective but, could have more mass, has a potential for leaks,
need more components, and could cost more. Maintenance and repair is more involved and costlier. • Indirect liquid cooling is easier to handle than direct liquid cooling.
Source: ‘Battery Thermal Management in EVs and HEVs:Issues and Solutions’, Advanced Automotive Battery Conference. NREL, Las Vegas, 2001
• Liquid Cooling vs Air Cooling
2. xEVs Battery Pack Cooling System Over View
• Discharge Test
Blower On/ Off & Discharge Test
• Test method
1. 2P6S Module 1ea 1C/1.75C/2.5C rate Discharged
2. 16 Points measuring
3. Non-Active Cooling / Active Air Cooling Measuring Temp change
Module
Dummy
Chamber①
1
Measuring Points
2 3
4
5
6
7
8
9
10
11
12
Airflow
②
13
14
15
16
Measuring Points(Amb Temp)
3. Li-Ion Module Discharging Test
• Discharge Test Results without Blower
40A Discharge: 60 min. 70A Discharge : 35 min.
100A Discharge : 25 min.
Tmax ≤ 34 °C and ΔTmax 5.3°C Tmax ≤ 42 °C and ΔTmax 7.6°C
Tmax ≤ 47 °C and ΔTmax 10.9°C
3. Li-Ion Module Discharge Test
• Result of 70A / 100A Discharge without Blower - Module Temp. 40 °C Increasing
• Case of High Current discharge: Cooling needs
• Discharge Test Results with Blower
40A Discharge: 60 min. 70A Discharge : 35 min.
100A Discharge : 25 min.
Tmax ≤ 31 °C and ΔTmax 4.4°C Tmax ≤ 34 °C and ΔTmax 5.9°C
Tmax ≤ 36 °C and ΔTmax 9.5°C
3. Li-Ion Module Discharge Test
• Result of 70A / 100A Discharge with Blower- Module Temp. max 36 °C : Stable
Discharge-
rate
Non Air Cooled (Blower Off) Air Cooled (Blower On)
∆T Min ∆T Max T Max ∆T Min ∆T Max T Max
1C =40A
60min4.4 5.3 34 1.4 4.4 31
1.75C=70A
35min4.7 7.6 42 1.8 5.9 34
2.5C=100A
25min6.0 10.9 47 5.0 9.5 36
• Active Air Cooled has over 15~20% cooling effect than Non-Air Cooled. • The case of non-air cooled, active cooling may needed when over 2.5C discharge because ofincreasing temperature.
3. Li-Ion Module Discharge Test
• Module cooling Test Results Summary
• Profile for 2.5C Discharge 15min. and 3C Charging 11min.
• 2.5C (100Ah*) discharge on 80% SOC Quick Char’g (11Min.)
• *100Ah: High Speed Driving, discharge consecutively 100Ah
Inlet_2 Inlet_1
Module
Outlet
② Temp. on Inlet_1③ Temp. on Inlet_2
④ Temp. on Outlet
⑤ Temp. outside of pack
① Temp. in chamberQuick Discharge Cycle – Quick Charge Cycle
4. Li-Ion Pack Temp Profile Test
• Temp Profile Test with Air Cooling
2.5 C
3.0 C
discharge
Charge
15 min
11 min
• Chamber Temp 0.2 ℃ ↑• Inlet_1 temp 0.5 ℃ ↑• Inlet_2 temp 0.6 ℃ ↑• Outlet temp 4.0 ℃ ↑• Ambient Temp 3.7 ℃ ↑
4. Li-Ion Pack Temp Profile Test
- TModule,max ≤ 44 °C and ΔTModule,max ≤ 23 °C- TModule,max > 40 °C, Cooling with A/C needed
2.5 C
3.0 C
discharge
Charge
15 min
11 min Module 20_1 Module 20_2
방전시작 21 21
방전 종료/충전시작 30 30
충전종료/방전시작 34 34
방전종료/충전시작 41 40
충전종료 44 43
13
Battery Temp
Vehicle Speed
Motor Torque
Initial Temp: 46 °C
Final Temp: 49 °C
• Ambient Temp: 43 °C• Battery Cooling: Air Blower (With A/Con)• EV Mode Driving 50kph 80kph• Battery Current: Discharge 20~30A (50 kph) 40~50 A (80kph)• Test Result: Amb temp 43 °C, 35 min. EV mode Driving Pack Mean Temp: ∆3 °C ↑
Mean: 20 Nm 28 Nm
Speed: 50 kph
Speed: 80 kph
5. EV Temp Profile Test in Hot Chamber
28 Nm
6. Conclusion & Future works
• Conclusion
1. Battery Pack Thermal management Range definition
- Keep 20~40 °C / case of T max 40 °C, Active cooling and Power Limit Strategy are required.
2. Test result of Module Active air Cooling and non-Air Cooling- non-Air Cooling: Discharge 1C/1.75C/2.5C, ∆T min 4.4 ~ ∆T max 10.9 Increasing, - Air Cooling: Discharge 1C/1.75C/2.5C, ∆T min 1.4 ~ ∆T max 9.5 Increasing Active Air Cooled has over 15~20% cooling effect than Non-Air Cooled.
3. Result for Profile Test of Battery Pack Temp. with Air cooling- Pack Air Inlet, Outlet ∆T=4 ℃ / Each Module surface temperature max ∆T=12 ℃, max T=44 ℃- Battery pack temp increasing, active cooling strategy are required. (Related Battery Life)
4. EV Battery Temp Test in Hot Chamber- Amb temp 43 °C, EV mode Driving 35 min. Pack Mean Temp: ∆3 °C ↑
• Future Works
1. Performance Comparison with Cooling with HVAC and Using Cabin air in vehicle level2. Performance Comparison of Battery Pack Temperature changing with Driving Modes
Thank you
E-mail: [email protected]