Method of controlling a three-phase permanent-magnet motor

A three-phase permanent-magnet motor is controlled by sequentially exciting and freewheeling phases of the motor over a plurality of sectors, where the phases are excited with a different voltage vector for each sector. The phases are freewheeled when a magnitude of phase current rises to an upper threshold, and freewheeling continues for either a fixed period of time or until the magnitude of the phase current decreases to a lower threshold. A parameter that corresponds to either the magnitude of the phase current during or at the end of freewheeling, or an interval between a start and end of freewheeling or a start and end of excitation is measured. A saturation event is determined to have occurred when the measured parameter is less than a saturation threshold. In response to the saturation event, the phases are commutated where a first saturation threshold is used when determining a saturation event within a first sector, and a second different saturation threshold is used when determining a saturation event within a second sector, or the phases are commutated multiple times in response to the saturation event.