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Update of SAE J2908 Activities

Mike DuobaArgonne National Laboratory

19 October 2015

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SAE J2908 History

J2907 – Motor Ratings J2908 – System Rating

• J2907/J2908 originally given SAE “J-doc” numbers more than 10 years ago, due to lack of progress, committee was tabled

• 2013: some meetings were held to restart J2907• Dec 2013: J2908 committee started recruiting members,

regular monthly meetings in 2014 and 2015• July 2014: Argonne started doing exploratory chassis dyno testing • March – July 2015: rented hub dyno for testing

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Basic Elements of J2908

1. Run a Test2. Collect Data3. Report Rating – Based upon test data & possibly other information

good progress

good progress

problems

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1. Run Test• Prep requirements varied slightly for each HEV design (SOC and Temps)• Found a few test procedure options to best achieve peak total

powertrain power for different types of HEVs• Hub dyno and chassis dyno (w/axle torque) were found to be equivalent

Hub Dyno

Chassis DynoWheel or axle torque sensor needed for power direct power measurements

or

or

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Different Test Types Were Developed for Different Powertrain Operation

Road load mode Road load mode

Fixed-Speed modeLow-Inertia, High ABC loads

Notes: - When speeds are changing quickly, inertia effects lower measured power. - Fixed Speed and Terminal Velocity tests are preferable.

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2. Collect Data• Measure DC electric power

– from battery– From accessories

• Monitor Powertrain Parameters– Engine: RPM, MAP, MAF, injection timing, reported torque– Other: gear #, powertrain states, reported RPM and torques of motors

• Measure Axle or Wheel Power– May or may not be required

Current and Voltage Measurements Vehicle Network Data Dynamometer Data

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3. Report Rating• J2908 is Currently stuck here!• Conflict between two objectives:

– Value to Consumer (rating allows comparisons to other vehicles)

– Ability to Verify (is information from OEM required?)

• Reporting options do not satisfy both objectives

Ability to Verify

Useful to Consumer (can compare to ICE Vehicles)

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From What Information is the “Net System Power” Rating Reported??

MG

2

Any Configuration

MG

1

Eng

BatteryAcc

Axle/Wheel Powermeasured

Engine Powerestimated +DC Powermeasured

Method

Method

Method

S Shaft Powersestimated

1

2

3

Three methods emerged

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Deciding on a Solution• If verifiability is of most importance, Method 3 will provide best data

without reliance on estimations• If 100% compatibility with conventional vehicle (engine-only) ratings are

of most importance, Method 2 provides that rating• Method 1 is partially compatible with existing ratings and partially

verifiable

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Application of Methods on Parallel HEV

Current OEM Catalog RatingsEngine: 123.7 kWMotor: 30 kW (mechanical)Total: 153.7 kW Method (1)123.7 + 35 = 158.7 kW(engine rating + measured battery power)

“Method (2)123.7 + 29 = 152.7 kW(engine rating + reported motor power)

Method (3)Total: 125 kW(measured axle kW)

Elecmeas = 35 kW

Engine assumed to be at rated power here

Motorest = 29 kW

Time

Axlemeas = 125 kW

• Engine appears to be at rated power (from data)• Method 1 and Method 2 are similar in value (small battery assist)• As expected, Method 3 provides much a lower power rating than

the other two.

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Application of Methods on Series HEV

Current OEM Catalog RatingsEngine: 105.1 kWMotor: 123.8 kW Total: 123.8 kW Method (1)105.1 + 42 = 147.1 kW(rated engine kW + measured battery kW)

Method (2)Series HEV output = only Motor kWMotor output: 124 kW(from CAN bus)

Method (3)Total: 116 kW(measured axle power)

Point at expected rated Eng kW- Peak fuel, peak RPM

Motorest = 124 kW

Axlemeas = 116 kW

Battmeas = 42 kW

• Engine appears to be at rated power (from data)• Method 2: Total power = Motor Power (CAN bus RPM and torque)• Method 1 and Method 2 are 23 kW different• Method 2 and Method 3 are different by only 8 kW

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Application of Methods on (another) Series HEV

Current OEM Catalog RatingsEngine: 63 kWMotor: 111 kW Total: 111 kW Method (1)61 + 80 = 141 kW(CAN bus engine kW + measured battery kW)

Method (2)Series HEV output = only Motor kWRated motor = 111 kW

Method (3)Total: 105 kW(measured axle power)

• Engine power taken from CAN bus, motor power at rated power• Method 1 has very high result, 30 kW higher than Method 2

80 kW

105 kW

61 kW

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Final Issue: Processing Results• All methods will require some filter applied to results• Data signals must be filtered for robust result (avoid transient spikes or signal noise)• Filter duration defines the duration period of peak power• We must decide duration of filter size recognizing this choice is arbitrary but uniform• Other viable methods besides window filter?

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J2908 Summary / Conclusions

• Test procedures should be flexible to achieve highest and most representative peak power

• Hybrids are transient in nature, definition of power is linked to duration (filter size)

• Must resolve Key Issue:– Should hybrid rating be molded to fit current

rating?– Should all vehicle power ratings switch basis to

wheel/axle power