Virtual Tests to Support Functional Safety of a Torque Vectored - - PowerPoint PPT Presentation

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Virtual Tests to Support Functional Safety of a Torque Vectored - - PowerPoint PPT Presentation

Mar 12, 2023 128 likes •387 views

Virtual Tests to Support Functional Safety of a Torque Vectored E-Motor Vehicle Richard Hurdwell & James Waters Virtual Testing Group September 2012 1 Outline Project Background and Objective The Vehicle Potential

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Virtual Tests to Support Functional Safety of a Torque Vectored E-Motor Vehicle

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Richard Hurdwell & James Waters Virtual Testing Group September 2012

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  • Project Background and Objective
  • The Vehicle
  • Potential Hazards and Risks
  • System Models
  • The Virtual Vehicle
  • Virtual Testing
  • Managing the results
  • HiL Testing
  • Acknowledgement

Outline

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Background

  • Independent E-Drive to individual wheels is a powerful enabler for torque vectoring
  • Risk from incorrect wheel torque delivery needs algorithms to detect and mitigate the

effect on the vehicle’s dynamics and controllability

  • Real testing of all of these possibilities and the effectiveness of mitigation is

impractical

  • This case study demonstrates how ahead of prototype running, virtual testing in SiL,

MiL and HiL developed the potential effectiveness of mitigation strategies

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  • Test potential effects on the vehicle of faults in E-Propulsion torque delivery
  • Establish and develop effectiveness of mitigation strategies
  • Support vehicle integration ahead of prototype vehicle running

Project Objective

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The Real Vehicle – Lotus 414e REEVolution

  • Torque Vectoring
  • Pair of axial flux electric motors per rear wheel
  • Driving a Single Speed Gearbox per wheel
  • 17 kWh Battery Pack
  • 35 kW Lotus Range Extender engine
  • 0-60mph: <4.0 sec
  • Vmax: 130mph
  • EV only range: 30 miles
  • Overall range 300 miles
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Powertrain Layout

  • Pair of axial flux electric motors per rear wheel
  • Driving a Single Speed Gearbox per wheel
  • 4x Lotus Controllers

Motor 1b Motor 1a Motor 2b Motor 2a

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Potential Hazards and Risk Scenarios

  • Lotus Functional Safety Team identified Potential Hazards with ASIL ratings for 414e

and restricted to its development on test tracks

  • Torque vectoring driveline creates particular hazards
  • Test runs were designed to exercise the defined hazards
  • Open and closed loop drivers tested to identify severity without driver interaction
  • Pass/Fail criteria agreed
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  • Methods to identify faults and mitigate the effects on the vehicle were developed e.g.
  • Whole system into freewheel
  • Affected wheel into freewheel, other wheel unchanged
  • To counter one motor short circuit torque, apply drive torque on paired motor
  • Test routines to establish effectiveness of mitigation were developed

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Mitigation Strategies

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  • Project Objective
  • The Vehicle
  • Hazards , Risks and Mitigation
  • System Models
  • The Virtual Vehicle
  • Virtual Testing
  • Managing the results
  • HiL Testing
  • Acknowledgement
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The Virtual Components - System Models

  • Each Engineering Function group contributes it’s own models:
  • Vehicle (Dynamics CAE Group)
  • Motor and HV Battery (CAE and HEV Group)
  • Control and Mitigation Strategies (Control Systems and Integration Group)
  • ESP (Brake systems proprietary model)
  • Each model’s fidelity and plausibility validated as far as possible using real world testing
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Virtual Vehicle Build & Commissioning

  • Assemble components into the Virtual Vehicle in IPG CarMaker for Simulink
  • Simulate the signal communication systems CANbus and IO
  • Add logic to simulate faults
  • Commission the virtual vehicle – fixing any cross system conflicts
  • Test drive the vehicle to develop systems and mitigation
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  • Project Objective
  • The Vehicle
  • Hazards , Risks and Mitigation
  • System Models
  • The Virtual Vehicle
  • Virtual Testing
  • Managing the results
  • HiL Testing
  • Acknowledgement
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Automate Test Manoeuvres and Pass Criteria

  • Automating tests with test manager allows rapid testing and re testing
  • Simple Log files record only the key data
  • 61 automated test scenarios plus variations resulted in nearly 3000 individual test runs
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Test Runs and Presentation of Results

  • Running the simulation is usually one of the shortest sections of work
  • Smart presentation of results enabled easy identification of failed tests
  • Mitigation strategies were refined or re-calibrated and the tests re-run
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Example - Compare Mitigation On/Off

Example Fault:

  • Left hand corner
  • 100 meter radius
  • Road Friction 1mu
  • Steady State
  • Fixed steer angle
  • Lateral Acceleration 8m/s
  • Outside Wheel Max Drive Torque
  • Inside Wheel Max Reverse Torque
  • Pass Criteria
  • yaw rate <5 deg/s
  • path deviation <0.5 m
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Comparison Mitigation On/Off

Mitigation Off Mitigation On

Pre Test: Steady State

Yaw Rate 0 deg/s, Deviation 0 Yaw Rate 0 deg/s, Deviation 0 m

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Comparison Mitigation On/Off

0 seconds: Fault Simulation Starts

Yaw Rate 0 deg/s, Deviation 0 m Mitigation Off Mitigation On Yaw Rate 0 deg/s, Deviation 0 m

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Comparison Mitigation On/Off

0.028 Seconds: Mitigation Disables Inverters Mitigation Off Mitigation On Yaw Rate 1.03 deg/s, Deviation 0.02 m Yaw Rate 1.03 deg/s, Deviation 0.02 m

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Comparison Mitigation On/Off

0.032 Seconds: Un-Mitigated Car fails Yaw Criteria Mitigation Off Mitigation On Yaw Rate 5.04 deg/s, Deviation 0.05 m Yaw Rate -0.11 deg/s, Deviation 0.03 m

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Comparison Mitigation On/Off

0.062 Seconds: Un-Mitigated Car fails Deviation Criteria Mitigation Off Mitigation On Yaw Rate 86.5 deg/s, Deviation 0.51 m Yaw Rate -1.03 deg/s, Deviation 0.05 m

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Comparison Mitigation On/Off

0.91 Seconds: Un-Mitigated Car spins Mitigation Off Mitigation On Yaw Rate 222.3 deg/s, Deviation 2.36 m Yaw Rate -0.8 deg/s, Deviation 0.12 m

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  • IPG X-Pac 4 HiL rig was used to test algorithms in the real Lotus controllers
  • HiL also enables the virtual vehicle to “drive” individual or multiple parts of the real

powertrain on the test bed

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HiL Testing

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  • Demonstrated how virtual testing developed potential effectiveness of mitigation strategy
  • This was essential ahead of prototype running for safer and quicker vehicle development
  • Algorithms to detect and mitigate the effect of faults developed with initial calibration
  • Helped develop the testing schedule for the real vehicle
  • Proved the need and targets for fast acting mitigation to control incorrect drive torques

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Summary

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This virtual testing process has been instrumental in the successful completion of a match funded collaborative research project “REEVolution” which was part funded by the UK’s Technology Strategy Board

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Acknowledgement

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CHINA 7th Floor, New Jinqiao Tower

  • No. 28 New Jinqiao Road, Pudong
  • Shanghai. PR CHINA 201206

Phone +86 (21) 5030 9990 Eng-china@lotuscars.com MALAYSIA Malaysia Sdn. Bhd. Lot G-5, Enterprise 3 Technology Park Malaysia Lebuhraya Puchong-Sungai Besi Bukit Jalil. 57000 Kuala Lumpur Phone +60 (3) 8996 7172 Eng-asia@lotuscars.com

Please reply to: Job title: Telephone: Email: Website: lotuscars.com/engineering

UNITED KINGDOM Potash Lane Hethel, Norwich NR14 8EZ Phone +44 (0) 1953 608423 Eng-uk@lotuscars.com USA 1254 N. Main Street Ann Arbor MI 48104 Phone +1 734 995 2544 Eng-usa@lotuscars.com

25 Richard Hurdwell Chief Engineer Active Dynamics & Virtual Testing

+44 1953 608 424

rhurdwell@lotuscars.com