VEHICLE ELECTRIFICATION INCREASES EFFICIENCY AND CONSUMPTION SENSITIVITY

VEHICLE ELECTRIFICATION INCREASES EFFICIENCY AND CONSUMPTION SENSITIVITY Henning Lohse-Busch, Ph.D. Argonne National Laboratory

Argonne s Center for Transportation Research Basic & Applied Combustion Research - Fuels and After treatment Modeling and Simulation - CFD Engine Combustion - Vehicle PT Energy & Controls Materials Research Tribology Thermal Mechanical Advanced Powertrain Research Facility EV-Smart Grid Interoperability Advanced Technology Vehicle Competition (Collegiate) 2

Advanced Powertrain Research Facility Technology Assessment Assess state-of-the-art transportation technology for the Department of Energy and Argonne research interests Codes and Standards Support codes and standards development with expertise and independent data Research Oriented Test Facilities 4WD chassis dynamometer Thermal Chamber: 0F to 95F Solar emulation opened 2002, upgraded 2011 2WD chassis dynamometer Up to medium duty opened 2009 Vehicle Technology Assessment Vehicle level Energy consumption (fuel + electricity) Emissions Performance Vehicle operation and strategy In-situ component & system testing Component performance, efficiency, and operation over drive cycles Component mapping Downloadable Dynamometer Database www.transportation.anl.gov/d3/ You can download all the data in Test summary this presentation and recreate the results analysis! 10Hz data of major signals Analysis Presentations The APRF team enabled this presentation 3

Overview American Retrospective on Automotive Efficiency Powertrain background Relentless Progress of Conventional Vehicle Powertrain Electrification Observations Electrification Complicates Efficiency Calculations Electrification Enables Higher Vehicle Efficiency Factors Impacting Energy Consumption Impact of Climate Control on Electric Vehicles Impact of Ambient Temperatures on Hybrid Electric Vehicles Cold Start Losses on Different Powertrains Summary Illustration 4

Vehicle Efficiency History in the United States Observations: From 1985 to 2005 fuel economy improved minimally while the engine power almost doubled. People buying trucks over cars increases CO2 average. In 2005 significant fuel economy improvements occurred corresponding to fuel price volatility at the pump and increased CAFE (Corporate Average Fuel Economy) EPA report updated annually: www.epa.gov/oms/fetrends.htm Adjusted CO2 Emissions (g/mi) 690 640 590 540 490 440 390 340 Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends: 1975 Through 2014 431 400 369 337 306 275 244 212 Adjusted CO2 Emissions (g/km) 6

EPA s 5 Cycles Tests for Fuel Economy Label EPA implemented the new 5 Cycle Fuel Economy Label to close the gap to real world fuel economy the consumer can expect. Classic cycles! Aggressive cycle! Extreme Temperatures! Speed [mph] Speed [mph] 80 70 60 50 40 30 20 10 80 70 60 50 40 30 20 10 FTP UDDS @ 75 Phase x10 #1 FCold start Trace #2 Hot start 0 0 200 400 600 800 1000 1200 1400 Time [s] HWFET @ 75 F Phase Trace 0 0 200 400 600 800 1000 1200 1400 1600 Time [s] CAFE (only city and highway) Speed [mph] 90 80 70 60 50 40 30 20 10 US06 @ 75 F Phase x10 Trace 0 0 100 200 300 400 500 600 Time [s] Parts of these cycles compute into a City and a Highway Fuel Economy Speed [mph] Speed [mph] 60 50 40 30 20 10 0 0 100 200 300 400 500 600 Time [s] 80 70 60 50 40 30 20 10 SC03 @ 95 F +850 W/m 2 UDDS @ 20 F Phase x10 Trace Phase x10 Trace 0 0 200 400 600 800 1000 1200 1400 Time [s] 7

Relentless Progress of Conventional Vehicles General technology improvement trends: 2004 Focus 2012 Focus Improved aerodynamics and lighter weight Advanced transmissions (high gear number, DCT, aggressive locking, CVT ) Advanced engines (VVT, GDI, turbo down sized, cylinder deactivation, ) Vehicle system level (start-stop, deceleration fuel cut off, accessory load electrification) Optimized engine loading Frequency Idle 2L PFI 4 spd auto 1000 rpm 1500 rpm 2L GDI 6 spd DCT Lowered engine speed for 2012 2000 rpm Acceleration Engine speed [rpm] Fuel cut off during deceleration Braking Acceleration Braking Engine not fueled Vehicle Speed Vehicle Speed 9

Engine Size, Transmission and Hybrid Efficiency Conventional HEV 4 cyl. 6 cyl. CVT 6 speed 6 speed 6 speed 8 speed 2013 Nissan Altima 2013 Hyundai Sonata 2011 Ford Fusion 2012 Ford Fusion 2012 Chrysler 300 City driving (UDDS cycle) 2010 Ford Fusion- Hybrid 2011 Hyundai Sonata- Hybrid Conventional HEV 4 cyl. 6 cyl. CVT 6 speed 6 speed 6 speed 8 speed 2013 Nissan Altima 2013 Hyundai Sonata 2011 Ford Fusion 2012 Ford Fusion 2012 Chrysler 300 2010 Ford Fusion- Hybrid 2011 Hyundai Sonata- Hybrid Highway driving (HWFET cycle) Vehicle efficiency depends on the driving style. City driving: transient and lower loads with idle periods impact efficiency Highway driving: higher steady engine loads for higher average efficiency Technology observation Engine size: smaller engine higher average efficiency CVT & 8 speed: enables optimized engine loading in city driving HEV: increased freedom to leverage engine operation and enables regenerative braking 10

Conventional and Hybrid Vehicle in City Driving 2013 Sonata Conventional: 8.2 l/100km Hybrid system enables: Engine Start-Stop 13 Sonata 2.4L EV Operation Engine Load Optimization Regenerative braking Accessory HV electrification (AC, PS, ) 11 Sonata HEV 2011 Sonata HEV: 4.9 l/100km 11

Engine Load Optimization with Hybrid Systems Spread engine operation 150 Engine is always ON 2013 Sonata 2.4L Engine is ON 32% of time 2011 Sonata HEV Clustered high load area Idle fuel Fuel Power [kw] 100 50 Fuel energy usage [kj] 0 500 1000 1500 2000 Engine speed [rpm] 500 1000 1500 2000 Engine speed [rpm] Data note: UDDS hot start @ 72F Ambient 12

How Much Energy Can Be Recovered? Braking Energy [Wh] City driving (UDDS cycle) 2010 Prius 2010 Sonata HEV 2011 Volt Highway driving (HWFET cycle) 2010 Prius 2010 Sonata HEV 2011 Volt Aggressive driving (US06 cycle) 2010 Prius 2010 Sonata HEV 2011 Volt The ability to recapture braking energy is fairly complicated and includes: Drive cycle Regen ramp in Max force and vehicle dynamics Limitation may be other then system limitation Other: Battery state of charge, Mode/gear shifting, powertrain warmup, drivability and safety issues (cornering, low friction roads, pot holes ) 13

Electrification Complicates Efficiency Calculations Conventional Vehicle Electric Vehicle 2012 Focus 2L Fuel 2013 Focus BEV Battery Engine Irreversible power flow Bi-directional power flow Motor 2000 2000 Energy [Wh] 1500 1000 500 Energy [Wh] 1500 1000 500 0 0 200 400 600 800 1000 1200 1400 Time [s] Efficiency = Energy Energy out in 0 0 200 400 600 800 1000 1200 1400 Time [s] Regenerative braking reverses the power flow and charges the high voltage battery (In & Out reverse) SAE J2951 defines Cycle Energy as the integration of positive power at the wheel over the cycle (regenerative braking = free energy) 14

Electrification Enables Higher Vehicle Efficiency Conventional 1.2 SAE J2951 definition Vehicle efficiency [%] 1 0.8 0.6 0.4 0.2 Data note: UDDS hot start 0 72F Peak ICE eff + regen Peak ICE eff Hybrid Electric 0.0 0.2 0.4 0.6 0.8 1.0 Degree of Hybridization (M/(M+E)) Battery Electric (incl. charger) Observations: Increased electrification provides efficiency increase in city type driving to a certain limit Pure electric Vehicles are not bound by ICE efficiency Conventional Hybrid Electric Battery Electric 2012 Ford Focus 2013 Jetta TDI 2013 Chevy Cruze Diesel 2013 Chevy Malibu Eco 2013 VW Jetta HEV 2013 Honda Civic HEV 2010 Prius 2013 Ford Cmax HEV 2014 Honda Accord HEV 2012 Nissan Leaf 2013 Nissan Leaf BEV 2015 BMW i3 BEV 2015 Chevy Spark BEV 2013 Ford Focus BEV 16

Different Factors Influencing Energy Consumption Impact of vehicle and driving style Power m ( V ) t F wheel = + roadload V Depends on: vehicle characteristics (mass, aero, tires, ) Driver: speed and acceleration Observations: Interdependence between wheel power and efficiency If powertrain efficiency is high and wheel energy low, the accessory loads can very become significant on energy consumption Energy = Impact of the powertrain Impact of accessory loads Efficiency Powerwheeldt + Powertrain ( Temp & Power wheel ) Power Efficiency AccLoads dt generation Powertrain types (CVs, HEVs, PHEVs, BEVs) influence the powertrain efficiency. Air conditioning system, electric heater, ECU, lights, 18

Higher Efficiency Powertrains Are More Sensitive Conventional Hybrid Electric Battery Electric (incl. charger) Observations: Everything matters down to the accessory loads in electric vehicles. SAE J2951 definition Data note: UDDS hot start Peak ICE eff + regen Peak ICE eff Conventional Hybrid Electric Battery Electric 2012 Ford Focus 2013 Jetta TDI 2013 Chevy Cruze Diesel 2013 Chevy Malibu Eco 2013 VW Jetta HEV 2013 Honda Civic HEV 2010 Prius 2013 Ford Cmax HEV 2014 Honda Accord HEV 2012 Nissan Leaf BEV 2013 Nissan Leaf BEV 2015 BMW i3 BEV 2015 Chevy Spark BEV 2013 Ford Focus BEV 19

Heater and Air Conditioning Impact on Electric Consumption 20F 72F 95F sun 20F 72F 95F 2012 Focus BEV 80 70 60 UDDS (City Driving) Phase x10 Trace Electric Vehicles are efficient. It takes about 4-5 kw of electricity on average to complete a city drive cycle Electric powertrains do not have enough waste heat to warm up the cabin in freezing temperatures An 4-6 kw electric heater is needed to warm up the cabin This more than doubles the energy consumption and cuts the range in half Speed [mph] 50 40 30 20 10 0 0 200 400 600 800 1000 1200 1400 Time [s] UDDS#1 (Cold Start) 20

Electric Range Depends on Drive Cycle, Ambient Temperature and Climate Control Settings 72F ambient Range [mi] 20F ambient 95F ambient + 850W/m 2 21

2010 Toyota Prius Fuel Consumption Results for Different Climate Control Modes Additional energy to heat up the cabin. Additional mechanical friction energy. Constant extra energy required to run the AC system. Warm ambient temperature helps improve powertrain efficiency. Permanent extra energy due to colder engine temperature and constant powertrain friction losses. Speed [mph] 80 70 60 50 40 30 10 Prius UDDS (City Driving) Phase x10 Trace 20 10 0 0 200 400 600 800 1000 1200 1400 Time [s] 22

Engine Operation of 2010 Prius on UDDS a Range of Ambient Temperatures Cold start UDDS 20F with heater 72F Cold start UDDS 95F (850 W/m 2 ) with AC Cold start UDDS Observations: 20F fuel island at lower speed load and engine usage very frequent 95F higher power level for AC and engine usage more frequent Hot start UDDS Hot start UDDS Hot start UDDS Fuel energy usage [kj] Speed [mph] 80 70 60 50 40 30 20 10 10 Prius UDDS (City Driving) Phase x10 Trace 0 0 200 400 600 800 1000 1200 1400 Time [s] EO = Engine On time in [%] Histogram is frequency 23

Cold Start Penalty at Different Temperatures Energy consumption increase between cold start and hot start UDDS 20F: Highest cold start penalty Penalty is due to high powertrain losses with high friction for all vehicles The losses during a cold start are higher for a powertrain using an engine 72F: Baseline 95F: PEVs show higher cold start penalties at 95F which may be due to cabin temperature pull down and higher baseline powertrain efficiencies 24

Using the Heater in an Electric Car may Double the Energy Consumption in City Type Driving Energy consumption [Wh/mi] 20F +91% Heater 72F 95F AC UDDS (City driving) +20% HWFET (Highway driving) US06 (Aggressive driving) Test Notes: Cold start vehicle soaked at target temperature for at least 12hr. Powertrain is hot in the other tests. Climate control setting to 72F automatic. 95F include 850 W/m2 of radiant energy. Electric Vehicle 2012 Nissan Leaf 26

Driving at Higher Speeds and Aggressively will Increase the Energy Consumption in an Electric Car 72F 72F 72F Energy consumption [Wh/mi] +19% +72% Electric Vehicle UDDS (City driving) HWFET (Highway driving) US06 (Aggressive driving) 2012 Nissan Leaf 27

Energy consumption [Wh/mi] Generally Increased Driving Intensity Translate to Higher Consumption Except for the Conventional due to Low Efficiency in the City 72F 72F 72F +4% +19% +5% -32% +60% +72% Conventional 2012 Ford Focus Full Hybrid 2010 Toyota Prius Electric Vehicle UDDS (City driving) HWFET (Highway driving) US06 (Aggressive driving) 2012 Nissan Leaf 28

Cold Start Energy Consumption is Larger than Hot Start Energy Consumption 20F 72F 95F Energy consumption [Wh/mi] +11% Heater +7% +12% AC UDDS (City driving) HWFET (Highway driving) US06 (Aggressive driving) Electric Vehicle 2012 Nissan Leaf 29

Largest Energy Consumption Increase for an EV Occurs at 20F and for a Conventional at 95F 20F 72F 95F Conventional Energy consumption [Wh/mi] +7% +91% Heater AC UDDS (City driving) +27% +65% +56% +20% Note: At 20F, the EV has to use an electric heater to heat the cabin and the conventional can use the engine heat. At 95F the conventional uses the mechanical compressor belted to the engine which is less efficient than the high voltage compressor in the EV. The powertrain operation change for hybrids at 20F and 95F compared to 72F. HWFET (Highway driving) US06 (Aggressive driving) 2012 Ford Focus Full Hybrid 2010 Toyota Prius Electric Vehicle 2012 Nissan Leaf 30

A Conventional Vehicle has the Largest Absolute Energy Consumption Penalty on a Cold Start 20F 72F 95F Conventional Energy consumption [Wh/mi] +15% +1% +11% Heater +7% +6% AC UDDS (City driving) +4% +8% +7% +12% HWFET (Highway driving) US06 (Aggressive driving) 2012 Ford Focus Full Hybrid 2010 Toyota Prius Electric Vehicle 2012 Nissan Leaf 31

Driving Usage and Climates Affect Energy Consumption Across Different Powertrains 20F 72F 95F 20F 72F 95F 20F 72F 95F Conventional Energy consumption [Wh/mi] Heater AC UDDS (City driving) Heater AC HWFET (Highway driving) Heater AC US06 (Aggressive driving) 2012 Ford Focus Full Hybrid 2010 Toyota Prius Electric Vehicle 2012 Nissan Leaf Test Notes: 1) Cold start vehicle soaked at target temperature for at least 12hr. Powertrain is hot in the other tests. 2) Climate control setting to 72F automatic. 3) 95F includes 850 W/m2 of radiant energy 32

VEHICLE ELECTRIFICATION INCREASES EFFICIENCY AND CONSUMPTION SENSITIVITY Henning Lohse-Busch, Ph.D. Argonne National Laboratory www.transportation.anl.gov/d3 Work sponsored by Lee Slezak and David Anderson from the Vehicle Technologies Office at the U.S. Department of Energy