Method and apparatus for operating an electric motor

Patent metadata

Field	Value
Publication number	US-2017359013-A1
Application number	US-201615182474-A
Country	US
Kind code	A1
Filing date	Jun 14, 2016
Priority date	Jun 14, 2016
Publication date	Dec 14, 2017
Grant date	—

Abstract

Apparatus and methods are provided for operating an electric motor, comprising selectively energising the coils of a stator having a plurality of stator teeth, each stator tooth having a said coil mounted thereon. The stator coils of a subset of the stator teeth are energised during a given time period to attract a corresponding rotor tooth into alignment with each of the stator teeth in the subset over the given time period. The stator coil of at least one stator tooth in the subset is energised during a portion of the given time period before the at least one stator tooth overlaps the corresponding rotor tooth.

First claim

What is claimed is:

1 . An electric motor comprising:
a stator comprising a plurality of stator teeth, each stator tooth having a stator coil mounted thereto; a rotor comprising a plurality of rotor teeth, the rotor being arranged to rotate relative to said stator during operation of the electric motor such that one or more of the rotor teeth periodically overlap with one or more of the stator teeth; and control circuitry to energise the stator coils of a subset of the stator teeth during a given time period to attract a rotor tooth into alignment with each of the stator teeth in the subset over the given time period, wherein, the control circuitry is configured to energise the stator coil of at least one stator tooth in the subset during a portion of the given time period before the at least one stator tooth overlaps the corresponding rotor tooth.

2 . The electric motor according to claim 1 , wherein the stator coil of the at least one stator tooth is not energised during a portion of the given time period when the at least one stator tooth at least partially overlaps the corresponding rotor teeth.

3 . The electric motor according to claim 1 , wherein the control circuitry is configured to further energise the stator coils of a second, different, subset of the stator teeth during a second time period, wherein the control circuitry is configured to energise the stator coil of at least one stator tooth in the second subset during a portion of the second time period before the stator teeth in the second subset overlap corresponding rotor teeth.

4 . The electric motor according to claim 1 , wherein the control circuitry is configured to energise the stator coils of the plurality of stator teeth during a period of the rotation of the rotor before the corresponding rotor teeth overlap with each respective stator tooth in the plurality.

5 . The electric motor according to claim 1 , wherein the control circuitry is configured to energise the stator coils of at least two of the stator teeth in the subset at different points during the given time period.

6 . The electric motor according to claim 5 , wherein the control circuitry is configured to energise the stator coils of the at least two stator teeth for non-overlapping portions of the given time period.

7 . The electric motor according to claim 5 , wherein the control circuitry is configured to energise the stator coils of the at least two stator teeth during the portion of the given time period before the stator teeth in the subset overlap the corresponding rotor teeth.

8 . The electric motor according to claim 5 , wherein the control circuitry is configured to energise the stator coil of at least one of the stator teeth in the subset during a portion of the given time period when the stator teeth in the subset at least partially overlap the corresponding rotor teeth.

9 . The electric motor according to claim 1 , comprising driver circuitry to generate pulse signals to energise said stator coils.

10 . The electric motor according to claim 9 , wherein the driver circuitry comprises boost generation circuitry and buck generation circuitry, wherein the stator coil of at least one of the stator teeth in the subset is energised using said boost circuitry during the given time period, and wherein the stator coil of at least one of the stator teeth in the subset is energised using said buck circuitry during the given time period.

11 . The electric motor according to claim 1 , wherein the stator teeth in the first subset are equally spaced circumferentially about the stator.

12 . The electric motor according to claim 11 , wherein the stator teeth in the first subset are arranged to each overlap a corresponding rotor tooth at substantially the same time during rotation of the rotor.

13 . The electric motor according to claim 1 , wherein the rotor tooth corresponding to a given stator tooth comprises the rotor tooth among the plurality of rotor teeth which is nearest to the given stator tooth at a given point during rotation of the rotor.

14 . Circuitry for an electric motor comprising:
driver circuitry to selectively energise the stator coils of a stator having a plurality of stator teeth, each stator tooth having a said stator coil mounted thereon; and control circuitry to cause the driver circuitry to energise the stator coils of a subset of the stator teeth during a given time period to attract a corresponding rotor tooth into alignment with each of the stator teeth in the subset over the given time period, wherein the control circuitry is configured to cause the driver circuitry to energise the stator coil of at least one stator tooth in the subset during a portion of the given time period before the at least one stator tooth overlaps the corresponding rotor tooth.

15 . A method of operating an electric motor, comprising:
selectively energising the coils of a stator having a plurality of stator teeth, each stator tooth having a said coil mounted thereon, the selective energising comprising: energising the stator coils of a subset of the stator teeth during a given time period to attract a corresponding rotor tooth into alignment with each of the stator teeth in the subset over the given time period, wherein the stator coil of at least one stator tooth in the subset is energised during a portion of the given time period before the at least one stator tooth overlaps the corresponding rotor tooth.

Assignees

• Advanced Risc Mach Ltd

Inventors

• Pietromonaco David Victor

Classifications

• H02P2201/11

  Buck converter, i.e. DC-DC step down converter decreasing the voltage between the supply and the inverter driving the motor · CPC title

• H02K19/103

  Motors having windings on the stator and a variable reluctance soft-iron rotor without windings · CPC title

• H02P25/086 Primary

  Commutation · CPC title

• H02P25/08

  Reluctance motors · CPC title

• H02P25/0925

  wherein the converter comprises only one switch per phase · CPC title