Compact direct drive in-wheel motors with integrated inverters,
control and brakes offer a number of distinct advantages compared
to conventional electric drive systems. The most obvious being that
the drivetrain is now packaged within the wheel freeing up space
elsewhere, in addition many driveline components and their
associated losses are eliminated and the vehicle efficiency,
response and handling can be improved. In new vehicle applications
this allows complete freedom for designers to optimize the vehicle
layout, have more usable space inside the vehicle body and enables
revolutionary vehicle concepts (which will become more important as
road space becomes scarce and taxation measures migrate towards
vehicle size). In retrofit applications the compact package allows
an electric drive to be added to any existing vehicle without
requiring any significant disruption to the vehicle platform to
keep integration costs down. This represents an opportunity for
OEM's to hybridize their existing vehicle portfolio in order to
address more stringent fleet-average emissions legislation.
Protean has retrofitted its Protean Drive™ in-wheel motors to
a variety of different vehicles in both pure EV and hybrid
configurations and has collated its findings over three years of
track and road testing. This paper will distil the practical
experience gained from these vehicle programs and illustrate some
of the challenges and solutions associated with in-wheel motor
integration. In doing so the paper deals with many of the key
vehicle level topics, such as the CAN interface, vehicle control
strategy, and brake integration.
