Torque ripple reduction in switched reluctance machine

• US 10,637,386 B2
• Filed: 07/26/2018
• Issued: 04/28/2020
• Est. Priority Date: 07/26/2018
• Status: Active Grant

• Current Assignee: Enedym Inc.
• Original Assignee: Enedym Inc.
• Inventors: Li, Haoding, Bilgin, Berker, Emadi, Ali
• Primary Examiner(s): Dinh, Thai T
• Application Number:
  US16/045,959
• Publication Number:
  US 20200036314A1
• Time in Patent Office: 642 Days
• CPC Class Codes: H02P 25/086 Commutation
• CPC Class Codes: H02P 25/098 Arrangements for reducing torque ripple

Abstract

Various embodiments are described herein for methods and systems for controlling a switched reluctance machine (SRM) having an axially extending rotor mounted to a shaft, an axially extending stator disposed coaxially and concentrically with the rotor, the rotor and stator having a plurality of salient poles, the stator poles protruding radially towards the rotor poles, and a plurality of electrical coils wound about the stator poles including a plurality of separate phase coils defining a plurality of phases of the SRM. In one example embodiment, the method comprises providing a control system operatively coupled to a current controller of the SRM, where the control system is configured to generate a unique set of current reference profiles based on an objective function and at least one constraint function and operating the SRM based on the unique set of current profiles generated by the control system.

Claims

1. A switched reluctance machine comprising:

an axially extending shaft;

an axially extending rotor mounted to the shaft, the rotor having a plurality of salient rotor poles;

an axially extending stator disposed coaxially and concentrically with the rotor, the stator having a plurality of salient stator poles protruding radially from the stator towards the rotor poles;

a plurality of electrical coils wound about the stator poles, the plurality of electrical coils including a plurality of separate phase coils defining a plurality of phases of the switched reluctance machine; and

a control system operatively coupled to a current controller for the switched reluctance machine, the control system being configured to generate a unique set of current reference profiles by minimizing an objective function while satisfying at least one constraint function, wherein the objective function comprises a first reference current and a second reference current, the first reference current for an outgoing phase at a present rotor position of the switched reluctance machine, the second reference current for an incoming phase at the present rotor position of the switched reluctance machine, the control system is configured to provide the unique set of current reference profiles to the current controller, and the current controller is configured to, for each phase coil, apply a phase current corresponding to a respective current reference profile to that phase coil to control the switched reluctance machine.

2. The switched reluctance machine of claim 1, wherein the control system is configured to receive a predetermined value of a weight parameter, σ

.

3. The switched reluctance machine of claim 2, wherein the objective function, J, comprises:

J=i_k²+σ

i_k-1²,

wherein;

i_k-1 represents the first reference current for the outgoing phase at the present rotor position of the switched reluctance machine,

i_k represents the second reference current for the incoming phase at the present rotor position of the switched reluctance machine; and

σ

represents a predetermined value of a weight parameter.

4. The switched reluctance machine of claim 1, wherein the at least one constraint function comprises:

0≤

i_k≤

i_rated

0≤

i_k-1≤

i_rated,

wherein;

i_k-1 represents the first reference current for the outgoing phase at the present rotor position of the switched reluctance machine,

i_k represents the second reference current for the incoming phase at the present rotor position of the switched reluctance machine; and

i_rated represents an allowable peak current for the switched reluctance machine.

5. The switched reluctance machine of claim 1, wherein the at least one constraint function comprises:

T_ref=T(i_k,θ

_k)+T(i_k-1,θ

_k-1),

wherein;

T_ref represents a reference torque for the switched reluctance machine,

T(i_k-1, θ

_k-1) represents a phase torque for the switched reluctance machine in the outgoing phase; and

T(i_k, θ

_k) represents a phase torque of the switched reluctance machine in the incoming phase.

6. The switched reluctance machine of claim 1, wherein the at least one constraint function comprises:

7. The switched reluctance machine of claim 1, wherein the control system is configured to generate the unique set of current reference profiles over a span of one electrical period.

8. The switched reluctance machine of claim 7, wherein the control system is configured to store the unique set of current reference profiles as a function of position of the rotor over the span of one electrical period.

9. A method of controlling a switched reluctance machine, the method comprising:

providing the switched reluctance machine, the switched reluctance machine comprising;

an axially extending shaft;

an axially extending rotor mounted to the shaft, the rotor having a plurality of salient rotor poles;

an axially extending stator disposed coaxially and concentrically with the rotor, the stator having a plurality of salient stator poles protruding radially from the stator towards the rotor poles; and

a plurality of electrical coils wound about the stator poles, the plurality of electrical coils including a plurality of separate phase coils defining a plurality of phases of the switched reluctance machine;

providing a control system operatively coupled to a current controller for the switched reluctance machine, the control system being configured to generate a unique set of current reference profiles by minimizing an objective function while satisfying at least one constraint function, wherein the objective function comprises a first reference current and a second reference current, the first reference current for an outgoing phase at a present rotor position of the switched reluctance machine, the second reference current for an incoming phase at the present rotor position of the switched reluctance machine; and

operating the switched reluctance machine based on the unique set of current profiles generated by the control system by, for each phase coil, applying a phase current corresponding to a respective current reference profile to that phase coil.

10. The method of claim 9, further comprising:

receiving a predetermined value of a weight parameter, σ

, by the control system to generate the objective function.

11. The method of claim 10, further comprising:

generating, by the control system, the objective function based on;

J=i_k²+σ

i_k-1²,

wherein;

i_k-1 represents the first reference current for the outgoing phase at the present rotor position of the switched reluctance machine,

i_k represents the second reference current for the incoming phase at the present rotor position of the switched reluctance machine; and

σ

represents a predetermined value of a weight parameter.

12. The method of claim 9, further comprising:

generating, by the control system, the at least one constraint function based on;

0≤

i_k≤

i_rated

0≤

i_k-1≤

i_rated,

wherein;

i_k-1 represents the first reference current for the outgoing phase at the present rotor position of the switched reluctance machine,

i_k represents the second reference current for the incoming phase at the present rotor position of the switched reluctance machine; and

i_rated represents an allowable peak current for the switched reluctance machine.

13. The method of claim 9, further comprising:

generating, by the control system, the at least one constraint function based on;

T_ref=T(i_k,θ

_k)+T(i_k-1,θ

_k-1),

wherein;

T_ref represents a reference torque for the switched reluctance machine,

T(i_k-1, θ

_k-1) represents a phase torque for the switched reluctance machine in the outgoing phase; and

T(i_k, θ

_k) represents a phase torque of the switched reluctance machine in the incoming phase.

14. The method of claim 9, further comprising:

generating, by the control system, the at least one constraint function based on;

15. A method of controlling a switched reluctance machine, the switched reluctance machine comprising an axially extending shaft, an axially extending rotor mounted to the shaft, an axially extending stator disposed coaxially and concentrically with the rotor, wherein the rotor has a plurality of salient rotor poles, and the stator has a plurality of salient stator poles protruding radially from the stator towards the rotor poles, and a plurality of electrical coils wound about the stator poles, the plurality of electrical coils including a plurality of separate phase coils defining a plurality of phases of the switched reluctance machine, the method comprising:

generating, by a control system operatively coupled to a current controller for the switched reluctance machine, a unique set of current reference profiles by minimizing an objective function while satisfying at least one constraint function, wherein the objective function comprises a first reference current and a second reference current, the first reference current for an outgoing phase at a present rotor position of the switched reluctance machine, the second reference current for an incoming phase at the present rotor position of the switched reluctance machine; and

operating the switched reluctance machine based on the unique set of current profiles generated by the control system by, for each phase coil, applying a phase current corresponding to a respective current reference profile to that phase coil.

16. The method of claim 15, further comprising:

receiving a predetermined value of a weight parameter, σ

, by the control system to generate the objective function.

17. The method of claim 16, further comprising:

generating, by the control system, the objective function based on;

J=i_k²+σ

i_k-1²,

wherein;

i_k-1 represents the first reference current for the outgoing phase at the present rotor position of the switched reluctance machine,

i_k represents the second reference current for the incoming phase at the present rotor position of the switched reluctance machine; and

σ

represents a predetermined value of a weight parameter.

18. The method of claim 15, further comprising:

generating, by the control system, the at least one constraint function based on;

0≤

i_k≤

i_rated

0≤

i_k-1≤

i_rated,

wherein;

i_k-1 represents the first reference current for the outgoing phase at the present rotor position of the switched reluctance machine,

i_k represents the second reference current for the incoming phase at the present rotor position of the switched reluctance machine; and

i_rated represents an allowable peak current for the switched reluctance machine.

19. The method of claim 15, further comprising:

generating, by the control system, the at least one constraint function based on;

T_ref=T(i_k,θ

_k)+T(i_k-1,θ

_k-1),

wherein;

T_ref represents a reference torque for the switched reluctance machine,

T(i_k-1, θ

_k-1) represents a phase torque for the switched reluctance machine in the outgoing phase; and

T(i_k, θ

_k) represents a phase torque of the switched reluctance machine in the incoming phase.

20. The method of claim 15, further comprising:

generating, by the control system, the at least one constraint function based on;