Abstract: A method of controlling a motor includes a) acquiring a rotational speed parameter; b) selecting either a three-phase modulation scheme and a two-phase modulation scheme based on a result of comparing a rotational speed of the motor with a predetermined reference speed; c) calculating phase voltage command values based on a target rotational speed and the rotational speed parameter; d) generating switching signals by using the selected modulation scheme based on the phase voltage command values; and e) outputting the switching signals to an inverter. In step b), the two-phase modulation scheme is selected when the rotational speed of the motor is higher than the reference speed to reduce switching loss is reduced and improve power efficiency without deteriorating starting characteristics and motor drive characteristics when the rotational speed is low.

Abstract: A method of controlling a motor includes a) acquiring a rotational speed parameter; b) selecting either a three-phase modulation scheme and a two-phase modulation scheme based on a result of comparing a rotational speed of the motor with a predetermined reference speed; c) calculating phase voltage command values based on a target rotational speed and the rotational speed parameter; d) generating switching signals by using the selected modulation scheme based on the phase voltage command values; and e) outputting the switching signals to an inverter. In step b), the two-phase modulation scheme is selected when the rotational speed of the motor is higher than the reference speed to reduce switching loss is reduced and improve power efficiency without deteriorating starting characteristics and motor drive characteristics when the rotational speed is low.