Patent ID: 7042189

Claim:
A method for controlling an electric motor comprising the steps of: a) choosing current turn-on and turn-off rotor-position angles for each motor phase to substantially maximize the absolute value of average motor torque when the motor is operating at a motor speed in one of four quadrants, wherein the first quadrant has positive motor torque and positive motor speed, wherein the second quadrant has negative motor torque and positive motor speed, wherein the third quadrant has negative motor torque and negative motor speed, and wherein the fourth quadrant has positive motor torque and negative motor speed; b) choosing current turn-on and turn-off rotor-position angles for each motor phase to substantially maximize the absolute value of average motor torque when the motor is operating at a motor speed in an other quadrant different from the one quadrant of step a); and c) operating the motor in each of the one quadrant of step a) and the other quadrant of step b); and d) limiting absolute value of motor speed if the motor is operating in the first or third quadrant but not if the motor is operating in the second or fourth quadrant.