CONTROL OF AN ELECTRIC MACHINE

摘要

A method of controlling a single-phase permanent -magnet electric machine comprising: exciting a winding of the electric machine in synchrony with zero-crossings of back emf in the winding when the electric machine operates over a first speed range; exciting the winding in advance of the zero-crossings by a fixed period of time when the electric machine operates over a second speed range; and exciting the winding in advance of the zero-crossings by a period of time that varies with speed when the electric machine operates over a third speed range. Additionally, a control system for an electric machine, and a vacuum cleaner incorporating the control system and electric machine.