An operating range (46) of angles is defined below a give angle and a second operating range (48) of angle is defined between the given first angle and a given second angle larger than the first. A third operating range(50) of angles is also defined. One of the three ranges is selected. The motor (23) is run in the first range with open control loop, in the second range by varying the angle according to the load (but without exceeding the given second angle) in order to maintain a give speed for angles less than the second given angle. In the third range the motor is run with the control loop closed.
