This paper explores the benefits in terms of efficiency, performance, safety and features that a drivetrain using dual and/or quad inboard axle-mounted motors has over that of a single-motor electric drivetrain. Several methods for improving efficiency by taking advantage of the possibilities of axle-mounted motors are explored and presented as an inventory of possible power request scenarios. It is argued that axlemounted drivetrains can provide a number of safety and convenience features over that of a single-motor electric drivetrain while maintaining or increasing electrical efficiency. The range of an affordable electric vehicle is arguably the largest deterrent to potential customers deciding between gas or electric. By improving drivetrain efficiency, axle-mounted motor drivetrains can help mitigate this roadblock by more effectively using the limited battery capacity available in an electric vehicle. The additional features of axle mounted motors (zeropoint turning, explicit advanced traction control) can be used to provide an additional draw for potential customers. Axle mounted motor drivetrains offer a baseline 5%-7% increase in operating efficiency due to the lack of geartrain losses. Additionally, left-right power variation and front-back power variation offer a theoretical maximum efficiency gain of 18% and 63% respectively. The main mechanic of efficiency gain is effectively a widening of a drivetrain's high-efficiency operating region due to intelligent satisfaction of power demand by multiple motors. More exploration must be done to optimize power shift ratio in scenarios where the steering wheel is only partially turned. Vehicle stability must be addressed further for implementation of axle-mounted motor drivetrains. With an aggressive power shifting strategy for efficiency, vehicle dynamics may become unpredictable to a driver who is used to a standard drivetrain. More effort must be placed on ensuring that the vehicle travels on the driver's intended path due to unintended power variance across the vehicle.
Analysis of dual and quad axle mounted motor drivetrain performance
EVS, Electric Vehicle Symposium, 26 ; 1078-1086
2012
9 Seiten, 18 Bilder, 2 Tabellen, 1 Quelle
Conference paper
English