Contribution to the RDE working group

Transcription

1 RDE testing of hybrid vehicles Contribution to the RDE working group 20 April 2016 European Commission - Joint Research Centre (JRC) IET - Institute for Energy and Transport Sustainable Transport Unit

2 Background RDE data evaluation verifies normality of test conditions Assumption: CO 2 emissions is a reliable proxy for power/work of the engine, therefore the severity of driving Assumption holds for conventional ICE vehicles but may not hold for hybrid vehicles propelled by ICE and electric engines Applying the current data evaluation may yield biased results or invalid tests for (plug-in) hybrid vehicles Degree of hybridization critical Mild hybrids: no electric driving, no external recharging, boost, start-stop Full hybrids: short electric driving, no external recharging Plug-in hybrids: extended electric driving, external recharging

3 Background With increasing hybridization: Robustness of CO 2 as indicator for driving severity decreases Range of operating conditions for a given driving event increases Increasing share of propulsion by electric engine Increasing likelihood of deviations in the powertrain management between driving on the road and during Type I test If data evaluation is to be applied to (plug-in) hybrids, electric energy drawn from the battery may need to be accounted for Robust coverage of operating conditions may require longer testing, e.g., multiple trips Emissions evaluation may not provide robust results for any set of normal conditions of use

4 Options Presented on 25 January 2016 Exempting hybrid vehicles from RDE testing Modified procedure RDE testing No modifications of the test procedure Unequal treatment of ICE vs. hybrid vehicles Determining CO 2 emissions and electricity consumption SOC (simple) SOC to CO 2 Current, voltage (advanced) Electric power to CO 2 Applying the current RDE data evaluation Abandoning RDE data evaluation for hybrid vehicles (Plug-in) hybrids may not be certifiable Unequal treatment of ICE vs. hybrid vehicles TA with Type 1 test in the lab Adaptations and application of App. 5 and 6 More detailed evaluation of strengths and limitations necessary 4

5 Options Option 1: Exclusion of hybrid vehicles from RDE testing Technically straight forward, no modification in the current RDE provisions needed Hybrids subject to less stringent regulation than conventional vehicles Definition of hybrid vehicles becomes critical (risk for legislative loop holes) => Option 1 may cause loop holes in the regulations and would reduce the robustness of RDE testing

6 Options 2 & 3 Modifying measurements No modifications Monitoring battery current and voltage or state of charge (SOC) Determining power at the wheels (torque meter or estimated) Other Modifying test trip requirements No change One trip in charge depleting mode Urban trip in charge depleting mode followed by one complete trip in charge sustaining mode Two trips (charge depleting and sustaining mode) Other => Various combinations feasible

7 Options Option 2: Modified measurements No modifications Monitoring state of charge (SOC); battery current and voltage Determining power at the wheels (torque meter or estimated) Other Modified test trip requirements No change One trip in charge depleting mode Urban trip in charge depleting mode followed by one complete trip in charge sustaining mode Two trips (charge depleting and sustaining mode) Other

8 Options Option 2: Measurements not modified - Data evaluation options Option 2: Appendices 5 and 6 problematic

9 Options Option 2: Measurements not modified - Data evaluation options Option 2a: Appendices 5 and 6 > NO Appendix 7 > YES Likely a small manufacturers risk of partially un-controlled driving Definition of hybrid vehicles may become critical Option 2b: Appendices 5 and 6 > YES, with modified references Appendix 7 > YES Appendix 5: modified CO 2 reference curve and reference value from WLTP lab tests Appendix 6: modified target function specific to hybrids Option 2a could be a valid and easy solution, provided that more data is used (e.g. extended urban driving and/or tests starting with different SOCs for PHEVs) Option 2b is technically more robust but requires adaptations of App 5/6

10 Options Option 3: Modified measurements Modified measurements and test design No modifications (Monitoring state of charge, SOC) or (battery current and voltage) or (Power at the wheels, torque meter or estimated) Modified test trip requirements No change One trip in charge depleting mode Urban trip in charge depleting mode followed by one complete trip in charge sustaining mode Two trips (charge depleting and sustaining mode) Other

11 Options Option 3: - Modified measurements - Data evaluation Option 3a: Monitoring state of charge (SOC); battery current and voltage Translation of electric energy consumption into equivalent CO 2 emissions via Willans lines Adjustments of Appendices 5 and 6 required: CO 2 reference curve (Appendix 5) Target function if power determined based on CO 2 emissions (Appendix 6)

12 Options Option 3b: Power at the wheels measured Appendix 5 adjustments required: Appendix 5: Recalculating power at the wheels into equivalent CO 2 emissions via Willans lines for lab and on-road testing Adaptation of CO 2 reference curve Appendix 6: no modifications needed =>Technically feasible but challenging Feasibility and accuracy on the road to be confirmed (calibration?) Linearity requirements for torque meters defined in RDE; no other regulatory reference Calculating power into equivalent CO 2 emissions subject to variability

13 Needs Expert knowledge/input for the discussion welcome Attention may need to be paid on the requested drive modes (e.g. eco, normal, )

14 Contacts Pierre Bonnel Theodoros Vlachos Barouch Giechaskiel Francesco Riccobono Martin Weiss: