Line start permanent magnet motor
AssigneeGeneral Electric Company
InventorJohn H. Boyd, Jr.
Life of this patent
Estimating the term…
Abstract
An electric motor including a stator having a stator core, a start winding and first and second main windings is described. The first main winding and the start winding are configured to form a lower number of poles than the second main windings. The stator core forms a stator bore. The motor also includes a rotor having a rotor shaft concentrically arranged axially of the stator core and a rotor core positioned concentrically with the rotor shaft. Secondary conductors are arranged axially of the rotor shaft and extend through the rotor core. A plurality of permanent magnets are located at an outer periphery of the rotor core and are magnetized to form a number of poles equal to the number of poles formed by the second main winding.
Claims29
A rotor for an electric motor, said rotor comprising:
- a rotor core including a plurality of laminations, each of said laminations having an outer periphery, a central rotor shaft opening, a plurality of secondary conductor openings radially offset from said outer periphery, and a plurality of notches having an open end at said outer periphery;
- a rotor shaft having an axis which is coaxial with a rotor core axis of rotation and extending through said central rotor shaft opening;
- a plurality of secondary conductors extending through said secondary conductor openings;
- and
- a plurality of permanent magnets located in said lamination notches, said permanent magnets having a T-shape cross-sectional shape.
An electric motor comprising:
- a stator comprising a stator core, first and second main windings, said first main winding configured to form a lower number of poles than said second main winding, said stator core forming a stator bore;
- and
- a rotor comprising a rotor shaft concentrically arranged axially of said stator core, a rotor core positioned concentrically with said rotor shaft and attached thereto, secondary conductors arranged axially of said rotor shaft and extending through said rotor core, a plurality of permanent magnets located at an outer periphery of said rotor core and magnetized to form a number of poles equal to the number of poles formed by said second main winding, said stator configured so that said rotor secondary conductors form a number of poles different from the number of poles formed by said second main winding.
An electric motor comprising:
- a stator comprising a stator core, first and second main windings, said first main winding configured to form a lower number of poles than said second main winding, said stator core forming a stator bore;
- a rotor comprising a rotor shaft concentrically arranged axially of said stator core, a rotor core positioned concentrically with said rotor shaft and attached thereto, secondary conductors arranged axially of said rotor shaft and extending through said rotor core, a plurality of permanent magnets located at an outer periphery of said rotor core and magnetized to form a number of poles equal to the number of poles formed by said second main winding, said stator configured so that said rotor secondary conductors form a number of poles different from the number of poles formed by said second main winding;
- and
- a switching unit having a first position and a second position, said switching unit being responsive to the rotational speed of said rotor and coupled to said stator windings to control the energization mode of said stator windings.
A method of operating an electric motor, the motor including a rotor having a rotor core, a rotor shaft, permanent magnets located at an outer periphery of the rotor core and secondary conductors extending through the rotor core, the motor further including a stator having a stator core and first and second main windings, the first main winding configured to form a lower number of poles than the second main winding, the stator core forming a stator bore, the rotor shaft concentrically arranged axially of the stator core, the rotor core positioned concentrically with the rotor shaft and attached thereto, said method comprising the steps of:
- at motor start-up, energizing the first main winding so that the rotor secondary conductors couple with the first main winding;
- and
- upon the occurrence of at least a first predetermined condition, energizing the second main winding and de-energizing the first main winding, wherein the rotor permanent magnets couple with the second main winding.
A lamination of a rotor for an electric motor, said lamination having a generally circular shape and an outer periphery, said lamination comprising a central opening sized to have a rotor shaft inserted therethrough, a plurality of secondary conductor openings arranged axially of said central opening and offset from said outer periphery, and a plurality of teeth portions at said outer periphery, wherein adjacent teeth portions define notches having a T-shape cross sectional shape.
Dependencies are inferred from the claim text.