CONTROL OF AN ELECTRIC MACHINE

摘要

A method of controlling a single-phase permanent-magnet electric machine, the method comprising: sequentially exciting and freewheeling a winding of the electric machine, wherein the winding is excited by an excitation voltage in advance of zero-crossings of back emf in the winding by an advance angle, and the winding is freewheeled over a freewheel angle; and varying the advance angle and the freewheel angle in response to changes in the excitation voltage. Additionally, a control system for an electric machine, and a vacuum cleaner incorporating the control system and electric machine.