Electronically controlled universal motor

Patent metadata

Field	Value
Publication number	US-9553494-B2
Application number	US-201514806868-A
Country	US
Kind code	B2
Filing date	Jul 23, 2015
Priority date	Nov 14, 2013
Publication date	Jan 24, 2017
Grant date	Jan 24, 2017

Abstract

An electric motor apparatus and method of controlling the same are provided. The electric motor apparatus includes a stator and a rotor rotationally mounted coaxially with the stator; an intermediate screen having a magnetic material and rotationally mounted between the stator and the rotor to provide magnetic screening between the rotor and the stator; and control circuitry to control power supplied to windings on the rotor and the stator in dependence upon a desired output rotational speed.

First claim

I claim:

1. An electric motor apparatus comprising:
a stator and a rotor rotationally mounted coaxially with said stator;
an intermediate screen comprising a magnetic material and rotationally mounted between said stator and said rotor to provide magnetic screening between said rotor and said stator; and
control circuitry to control power supplied to windings on said rotor and said stator in dependence upon a desired output rotational speed.

2. An electric motor according to claim 1 , wherein said stator and said rotor comprise a same number of windings.

3. An electric motor according to claim 1 , wherein said intermediate screen comprises a plurality of inserts on at least one of said inner and outer surfaces of a highly electrically conductive material, said plurality of inserts running at an offset angle to said longitudinal axis to form a squirrel cage, said plurality of inserts on a same surface being coupled at either end to form loops.

4. An electric motor according to claim 3 , wherein said intermediate screen comprises said plurality of inserts on both said inner and outer surfaces.

5. An electric motor according to claim 4 , wherein said plurality of inserts on said inner surface are arranged at different circumferential positions to said plurality of inserts on said outer surface.

6. An electric motor according to claim 5 , wherein said intermediate screen comprises a plurality of protrusions extending from said intermediate screen on at least one of said inner and outer surfaces.

7. An electric motor according to claim 6 , wherein said intermediate screen comprises said plurality of protrusions on both said inner and outer surfaces.

8. An electric motor according to claim 7 , wherein said inner and said outer surface comprise a same number of said plurality of protrusions, said plurality of protrusions on said inner surface being offset compared to said plurality of protrusions on said outer surface, such that a protrusion on said inner surface is not formed at a same circumferential position as a protrusion on said outer surface.

9. An electric motor according to claim 8 , wherein said protrusions are formed by said inner and outer surfaces being undulating surfaces, said undulating surfaces undulating at a substantially same rate and same direction such that a thickness of said intermediate screen is substantially constant around the circumference.

10. An electric motor according to claim 1 , wherein said rotor is mounted on an axle and said intermediate screen is mounted on said axle.

11. An electric motor according to claim 1 , wherein said control circuitry comprises a stator control unit and a rotor control unit, said rotor control unit being mounted on said rotor.

12. An electric motor according to claim 11 , wherein
said stator control unit is configured to control power supplied to said windings on said stator to thereby generate a rotational force on said intermediate screen; and
said rotor control unit is configured to control power supplied to said windings on said rotor to thereby generate a rotational force between said intermediate screen and said rotor, said rotational force exerted on said rotor being dependent on a rotational speed of said intermediate screen due to said rotational force generated by said stator and said rotational force generated between said intermediate screen and said rotor by power supplied to said windings of said rotor.

13. An electric motor according to claim 12 , wherein said rotational forces generated by said stator control unit and said rotor control unit are combined via said intermediate screen to generate a cumulative rotational force on said rotor.

14. An electric motor according to claim 11 , further comprising a rotational position sensor configured to generate rotational position information indicative of a relative orientation of said intermediate screen and said rotor and said intermediate screen and said stator,
said rotor control unit mounted on said rotor being coupled to a power supply supplied to said rotor and configured to generate a rotor power supply waveform from said power supply in dependence upon said rotational position information and a desired output frequency of rotation of said rotor relative to said intermediate screen and to apply said rotor c power supply waveform to said rotor; and
said stator control unit being coupled to a power supply supplied to said stator and configured to generate a stator power supply waveform from said power supply in dependence upon said rotational position information of said intermediate screen and said stator and a desired output speed of rotation and to apply said stator power supply waveform to said stator.

15. A method of operating an electric motor apparatus, said electric motor apparatus comprising: a stator and a rotor rotationally mounted coaxially with said stator; an intermediate screen comprising a magnetic material rotationally mounted between said stator and said rotor to provide magnetic screening between said rotor and said stator, said method comprising:
controlling an output rotational speed of said motor by providing power to windings on either said rotor or said stator, or on said rotor and said stator.

16. An electric motor apparatus comprising:
a stator means and a rotor means rotationally mounted coaxially with said stator means;
an intermediate screening means for providing magnetic screening comprising a magnetic material between said rotor means and said stator means, said intermediate screening means being rotationally mounted between said stator means and said rotor means; and
control means for controlling power supplied to windings on said rotor means and said stator means in dependence upon a desired output rotational speed.

Assignees

• Advanced Risc Mach Ltd

Inventors

• Pietromonaco David

Classifications

• H02K16/02 Primary

  Machines with one stator and two {or more} rotors · CPC title

• H02K17/24

  in which both stator and rotor are fed with AC · CPC title

• H02P25/024

  controlled by supply frequency · CPC title

• H02K99/20

  Motors · CPC title

• H02K1/06 Primary

  characterised by the shape, form or construction · CPC title