wave current waveform trajectory i sq t of the desired phase current i di t supplied to the controller 44 the replacement of the high efficiency control scheme with the high torque control scheme results in a higher torque needed when torque obtainable with the high efficiency control scheme is not sufficient for the cruise control system to maintain a desired speed however the motor operating at the high torque control scheme sacrifices some of the efficiency achievable with the sinusoidal waveform profile accordingly it would be desirable to maintain operations with a substantially sinusoidal waveform profile of the phase current i di as long as the required torque is achievable using the high efficiency control scheme the cruise control system of the present invention utilizes the phase advance technique to achieve an extended range of operation with current of sinusoidal waveform trajectory i sin t for achieving higher efficiency the extended range is provided by controlling the phase advance angle u03b1 between the current vector and the back emf vector for achieving a higher torque using the phase advance technique the per phase desired current trajectories are selected according to the following expression i di t i opti sin n r u03b8 i u03b1 opti where i di denotes per phase desired current trajectory i opti is per phase optimal current amplitude n r is the number of permanent magnet pole pairs u03b8 i represents relative.