Patent ID: 8120297

Claim:
A method of starting and controlling a single phase alternating current driven motor capable of synchronous operation comprising a rotor with poles and a stator the stator having at least one energising coil winding per pole, by: supplying switched sinusoidal single phase alternating current from an alternating current supply through at least one part of a pole energising coil winding separate from the remainder of that pole energising coil winding in a switched manner synchronously with the alternating current supply to the motor to start the motor in a rotational direction; detecting when the rotational direction is incorrect and removing the alternating current supply and allowing the motor to stop; continuously determining the required rotor position relative to a desired rotor position; controlling the connection of supply current to the pole energising coils or pole energising coil parts by: detecting when at least one of the pole energising coils or coil parts could, if energised, supply an accelerating torque to the rotor to bring the rotor towards the desired position; accelerating the rotor towards a desired rotor position or maintaining the motor at a desired rotor position corresponding to a selected rotational rate by connecting a supply current from the alternating current supply to that pole energising coil or coil part which can provide an accelerating torque and connecting that supply current for at least part of the period during which it could provide an accelerating torque accelerating the rotor towards a synchronous rotation rate; wherein the torque of the motor is controlled by controlling the switched alternating current supply to each pole energising winding part separated from the remainder of each pole energising coil winding and to the complete pole energising winding such that the part provides a torque at a rotor position differing from that of the complete pole energising coil winding.