Keywords: vehicle safety, running performance, next–generation electric vehicles, front wheel independent drive, rear wheel independent drive, in–wheel motor drive, front wheels, rear wheels, lithium battery, driving performance, road surface conditions, road conditions
Running performance of front–and–rear–wheel–independent–drive–type electric vehicle suitable for next–generation electric vehicles
A front–and–rear–wheel–independent–drive–type–electric vehicle (FRID EV) is being developed as the next–generation EV with optimum characteristics compatible with driving performance and safety. Development of the FRID EV has involved studying the driving performance and safety of all types of propulsion systems. Since the FRID EV has propulsion systems that can control the driving and braking torques of the front and rear wheels independently, various outstanding and indispensable functions suitable for next–generation vehicle are realised. Three novel functions are demonstrated here experimentally: 1) a failsafe function under which vehicles continue running without any unexpected sudden stops, even if one of the propulsion systems fails; 2) a function for performing efficient acceleration and deceleration on all roads by suitably distributing the driving or braking torques between the front and rear wheels according to the road surface conditions; 3) a function for ensuring safe running on bad roads, i.e., low–µ roads such as icy roads, by simultaneously controlling the slip ratios of the front and rear wheels considering load movement. These functions are unique to the FRID EV and have not been realised previously in any gasoline engine–powered car, hybrid car, or conventional electric vehicle.