A method of controlling a brushless permanent magnet motor

摘要

A brushless permanent magnet motor 14 is controlled by measuring a mains power supply voltage of the motor and determining whether the mains power supply voltage lies within a first range representative of a first country's mains power supply or a second range representative of a second country's mains power supply. Commutation of a winding 22 of the motor is advanced relative to a zero-crossing of back EMF in the winding 22 where the mains power supply voltage lies within the first range, and retarded relative to a zero-crossing of back EMF in the winding 22 where the mains power supply voltage lies within the second range. The first range may comprise voltages lower than voltages within the second range. Each half of an electrical cycle may be divided into at least one energisation period and at least one de-energisation period, and where the mains power supply voltage lies within the second range, the energisation period may comprise a single energisation period, the de-energisation period may comprise a single de-energisation period, and the de-energisation period may occur after the energisation period.