A SYSTEM FOR CONTROLLING A ROTARY DEVICE

摘要

A system for controlling a rotatable device, the system comprising a controller and a rotary device, which has a stator and rotor, wherein the controller is connected to the rotary device to control rotation of the rota ry device, and wherein the controller is adapted to periodically energies at least one energising coil of the device to create a magnetic field of a polarity which induces the rotor to rotate in a single direction and wherein the controller is switched off so as to de-energise the energising coil when other forces, being forces other than those resulting from the energised energising, coil produce a resultant force which induces rotation of the rot or in the single direction.