A novel cruise control system is provided for adaptively controlling an electric
vehicle to maintain desired speed under variable driving conditions. This system
utilizes multiple motor control scheme for controlling the motor using various
waveform profiles of the control current, and involves phase advance angle adjustment
provided for adaptively controlling a phase advance angle between the control current
and back-EMF in response to changes in driving conditions to produce the control
current sufficient to achieve the desired speed. A motor control scheme selection
circuit enables the cruise control system to select a current waveform profile
appropriate for present driving conditions. A selected current waveform profile
is modified, if the control current with the adjusted phase advance angle is not
sufficient to achieve the desired speed.
