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Model-based Development of Future Small EVs using Modelica Yutaka Hirano Shintaro Inoue Junya Ota Toyota Motor Corporation, Future Project Division 1200 Mishuku, Susono, Shizuoka, 410-1193 JAPAN {yutaka_hirano, shintaro_inoue_aa, junya_ota}@mail.toyota.co.jp To cope with demands for future low carbon society, development of new-type small electric vehicles (EVs) becomes very active. To reduce the energy consumption in various actual driving conditions, considering overall running resistance such as aero- dynamic resistance, tire rolling resistance including cornering drag, mechanical and elec- trical losses, etc. will be necessary. On the other hand, to cope with reduced stability against external disturbances such as side wind because of the light weight, it was clari- fied that additional control of direct yaw moment is effective. In this paper, model-based development of a new electric vehicle using Modelica is described. Full vehicle model considering both vehicle dynamics and energy consumption was developed as shown in Figure 1 and utilized to investigate the best possible solutions for both basic design of the vehicle and design of the control system. There are three points in this paper. First, the influence of tire rolling resistance coeffi- cient (RRC) and tire cornering power (CP) and also the vehicle weight for overall driving resistance and energy consumption was investigated. It became clear that light vehicle weight, low RRC value and high CP value are effective to reduce the overall driving resistance and thus energy consumption as Figure 2. Secondly, it was also proved that light vehicle weight tends to result in reduced vehicle stability against external disturbances such as side wind. To cope with this problem, a new direct yaw moment control using a torque vectoring differential gear (TVD) was pro- posed. Also detailed investigation about dynamic performance and energy consumption of the new TVD systems was done. Third point is that capability of recuperating breaking energy is also essential to im- prove the energy consumption. To clarify the necessary specification of the electric power system, the estimation of driving and breaking powers in various driving conditions were performed. Finally estimation of proper battery capacity for breaking power regeneration for various driving conditions was done. It was evident that Modelica was very powerful to perform this kind of multi-physics and multi-discipline investigations for the holistic vehicle systems and control design in the early phase of development planning. Top layer Controller Controller Torque vectoring Torque vectoring differential gear differential gear Suspension and tires Suspension and tires Figure 1: Total vehicle model m:600kg RRC:6 CP:16.1 m:600kg RRC:6 CP:13 Cornering Resistance [N] 43%down 0 50 100 150 200 250 17%down 3%down m:1050Kg RRC:9.5 CP:16.1 Light weight Conventional vehicle New vehicle Low RRC tire L&N tire m:600Kg RRC:9.5 CP:16.1 Figure 2: Comparison of cornering resistance force for various design condition

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Model-based Development of Future Small EVsusing Modelica

Yutaka Hirano Shintaro Inoue Junya OtaToyota Motor Corporation, Future Project Division

1200 Mishuku, Susono, Shizuoka, 410-1193 JAPAN{yutaka_hirano, shintaro_inoue_aa, junya_ota}@mail.toyota.co.jp

To cope with demands for future low carbon society, development of new-type smallelectric vehicles (EVs) becomes very active. To reduce the energy consumption in vari-ous actual driving conditions, considering overall running resistance such as aero-dynamic resistance, tire rolling resistance including cornering drag, mechanical and elec-trical losses, etc. will be necessary. On the other hand, to cope with reduced stabilityagainst external disturbances such as side wind because of the light weight, it was clari-fied that additional control of direct yaw moment is effective. In this paper, model-baseddevelopment of a new electric vehicle using Modelica is described. Full vehicle modelconsidering both vehicle dynamics and energy consumption was developed as shown inFigure 1 and utilized to investigate the best possible solutions for both basic design of thevehicle and design of the control system.

There are three points in this paper. First, the influence of tire rolling resistance coeffi-cient (RRC) and tire cornering power (CP) and also the vehicle weight for overall drivingresistance and energy consumption was investigated. It became clear that light vehicleweight, low RRC value and high CP value are effective to reduce the overall driving re-sistance and thus energy consumption as Figure 2.

Secondly, it was also proved that light vehicle weight tends to result in reduced vehi-cle stability against external disturbances such as side wind. To cope with this problem, anew direct yaw moment control using a torque vectoring differential gear (TVD) was pro-posed. Also detailed investigation about dynamic performance and energy consumptionof the new TVD systems was done.

Third point is that capability of recuperating breaking energy is also essential to im-prove the energy consumption. To clarify the necessary specification of the electric powersystem, the estimation of driving and breaking powers in various driving conditions wereperformed. Finally estimation of proper battery capacity for breaking power regenerationfor various driving conditions was done.

It was evident that Modelica was very powerful to perform this kind of multi-physicsand multi-discipline investigations for the holistic vehicle systems and control design inthe early phase of development planning.

Top layer

ControllerControllerTorque vectoringTorque vectoringdifferential geardifferential gear

Suspension and tiresSuspension and tires

Figure 1: Total vehicle model

m:600kgRRC:6CP:16.1

m:600kgRRC:6CP:13

Cor

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