Method and system for estimating electrical angular speed of a permanent magnet machine

• US 8,664,901 B2
• Filed: 02/15/2012
• Issued: 03/04/2014
• Est. Priority Date: 02/15/2012
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Son, Yo Chan, Gallegos-Lopez, Gabriel, Hiti, Silva, Perisic, Milun
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US13/397,463
• Publication Number:
  US 20130207579A1
• Time in Patent Office: 748 Days
• Field of Search: 318/400.21, 318/599, 318/800, 318/801, 318/810, 318/811
• US Class Current: 318/400.21
• CPC Class Codes: H02P 21/18 Estimation of position or speed
• CPC Class Codes: H02P 21/24 Vector control not involving the use of rotor position or rotor speed sensors

Abstract

Methods, systems and apparatus are provided for estimating electrical angular speed of a permanent magnet machine based on two-phase stationary reference frame feedback stator current samples, and a dimensionless gain (K) that is computed based on a sampling time (T) and machine parameters.

Claims

1. A method for computing an estimated electrical angular speed of a permanent magnet machine, comprising:

determining, at an electrical angular speed estimator module, whether three or more two-phase stationary reference frame feedback stator current samples (i_α

(k), i_α

(k+1), i_α

(k+2), i_β

(k), i_β

(k+1), i_β

(k+2)) have been stored;

when three or more two-phase stationary reference frame feedback stator current samples (i_α

(k), i_α

(k+1), i_α

(k+2), i_β

(k), i_β

(k+1), i_β

(k+2)) have been stored at the electrical angular speed estimator module;

computing, at the electrical angular speed estimator module, an estimated electrical angular speed (ω

_est(k)) of the permanent magnet machine based on the three or more two-phase stationary reference frame feedback stator current samples (i_α

(k), i_α

(k+1), i_α

(k+2), i_β

(k), i_β

(k+1), i_β

(k+2)) stored at the electrical angular speed estimator module, and a dimensionless gain that is computed based on a sampling time (T) and machine parameters.

2. A method according to claim 1, wherein the machine parameters comprise:

a stator inductance (L_s) and a stator resistance (R_s).

3. A method according to claim 1, wherein the permanent magnet machine is a surface mount permanent magnet machine, and wherein the step of computing comprises:

computing, at the electrical angular speed estimator module, the estimated electrical angular speed (ω

_est(k)) of the surface mount permanent magnet machine (SMPMM) based on an equation;

4. A method according to claim 3, wherein the dimensionless gain (K) is computed based on an equation:

5. A method according to claim 4, wherein the first α

-axis current difference (di<sub>α

1</sub>), the second α

-axis current difference (di<sub>α

2</sub>), the first β

-axis current difference (di<sub>β

1</sub>), and the second β

-axis current difference (di<sub>β

2</sub>) are computed based on equations;

di<sub>α

1</sub>=i_α

(k+1)−

Ki_α

(k),

di<sub>α

2</sub>=i_α

(k+2)−

Ki_α

(k+1),

di<sub>β

1</sub>=i_β

(k+1)−

Ki_β

(k),

di<sub>β

2</sub>=i_β

(k+2)−

Ki_β

(k+1),

respectively, and wherein k is an index that corresponds to a first sample point, K is the dimensionless gain, i_α

(k) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at the first sample point, i_α

(k+1) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at a second sample point, i_α

(k+2) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at a third sample point, i_β

(k) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the first sample point, i_β

(k+1) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the second sample point, and i_β

(k+2) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the third sample point.

6. A method according to claim 1, wherein the permanent magnet machine is an interior permanent magnet machine, and wherein the step of computing comprises:

computing, at the electrical angular speed estimator module, the estimated electrical angular speed (ω

_est(k)) of the interior permanent magnet machine (IPMM) based on an equation;

7. A method according to claim 6, wherein the dimensionless gain comprises a dimensionless gain matrix K(k) that is computed based on an equation:

8. A method according to claim 7, wherein the first α

-axis/β

-axis current difference (di<sub>α

1/β</sub>

), the second α

-axis/β

-axis current difference (di<sub>α

2/β

1</sub>), the first β

-axis/α

-axis current difference (di<sub>β

1/α</sub>

), and the second β

-axis/α

-axis current difference (di<sub>β

2/α

1</sub>) are computed based on equations;

di<sub>α

1/β</sub>

=i_α

(k+1)−

k₁i_α

(k)−

k₂i_β

(k),

di<sub>α

2/β

1</sub>=i_α

(k+2)−

k₁i_α

(k+1)−

k₂i_β

(k+1),

di<sub>β

1/α</sub>

=i_β

(k+1)−

k₁i_β

(k)+k₂i_α

(k),

di<sub>β

2/α

1</sub>=i_β

(k+2)−

k₁i_β

(k+1)+k₂i_α

(k+1),

respectively, where k₁ is a diagonal element of the dimensionless gain matrix K(k) and k₂ is a sub-diagonal element of the dimensionless gain matrix K(k), i_α

(k) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at the first sample point, i_α

(k+1) is a two-phase a-axis component of the stationary reference frame feedback stator current sample at a second sample point, i_α

(k+2) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at a third sample point, i_β

(k) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the first sample point, i_β

(k+1) is two-phase β

-axis component of the stationary reference frame feedback stator current sample at the second sample point, and i_β

(k+2) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the third sample point.

9. A method according to claim 1, further comprising:

detecting, at a fault detection and confirmation module, that a fault condition has occurred; and

communicating, a command to an open/short controller module to enter a three-phase short operating mode.

10. A method according to claim 1, further comprising:

sampling, at an abc reference frame-to-α

β

reference frame transformation module, samples of three-phase stationary reference frame feedback stator currents (i_sa . . . i_sc);

transforming, at the abc reference frame-to-α

β

reference frame transformation module, the three-phase stationary reference frame feedback stator current samples (i_sa(k) . . . i_sc(k)) into two-phase stationary reference frame feedback stator current samples (i_α

(k), i_β

(k)); and

storing, at the electrical angular speed estimator module, the two-phase stationary reference frame feedback stator current samples (i_α

(k), i_β

(k)).

11. A drive system for a permanent magnet machine, the drive system comprising:

a controller, comprising;

an electrical angular speed estimator module configured to compute an estimated electrical angular speed (ω

_est(k)) of the permanent magnet machine based on three or more two-phase stationary reference frame feedback stator current samples (i_α

(k), i_α

(k+1), i_α

(k+2), i_β

(k), i_β

(k+1), i_β

(k+2)), and a dimensionless gain (K) that is computed based on a sampling time (T) and machine parameters.

12. A system according to claim 11, wherein the machine parameters comprise:

a stator inductance (L_s) and a stator resistance (R_s).

13. A system according to claim 11, wherein the permanent magnet machine is a surface mount permanent magnet machine, and wherein the electrical angular speed estimator module is configured to compute the estimated electrical angular speed (ω

_est(k)) of the surface mount permanent magnet machine based on an equation;

14. A system according to claim 13, wherein the dimensionless gain (K) is computed based on an equation:

15. A system according to claim 14, wherein the electrical angular speed estimator module is configured to compute the first α

-axis current difference (di<sub>α

1</sub>), the second α

-axis current difference (di<sub>α

2</sub>), the first β

-axis current difference (di<sub>β

1</sub>), and the second β

-axis current difference (di<sub>β

2</sub>) based on equations;

di<sub>α

1</sub>=i_α

(k+1)−

Ki_α

(k),

di<sub>α

2</sub>=i_α

(k+2)−

Ki_α

(k+1),

di<sub>β

1</sub>=i_β

(k+1)−

Ki_β

(k),

di<sub>β

2</sub>=i_β

(k+2)−

Ki_β

(k+1),

respectively, where k is an index that corresponds to a first sample point, K is the dimensionless gain, i_α

(k) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at the first sample point, i_α

(k+1) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at a second sample point, i_α

(k+2) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at a third sample point, i_β

(k) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the first sample point, i_β

(k+1) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the second sample point, and i_β

(k+2) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the third sample point.

16. A system according to claim 11, wherein the permanent magnet machine is an interior permanent magnet machine, and wherein the electrical angular speed estimator module is configured to compute the estimated electrical angular speed (ω

_est(k)) of the interior permanent magnet machine based on an equation;

17. A system according to claim 16, wherein the dimensionless gain comprises a dimensionless gain matrix K(k), wherein the electrical angular speed estimator module is configured to compute the dimensionless gain matrix K(k) based on an equation:

18. A system according to claim 17, wherein the first α

-axis/β

-axis current difference (di<sub>α

1/β</sub>

), the second α

-axis/β

-axis current difference (di<sub>α

2/β

1</sub>), the first β

-axis/α

-axis current difference (di<sub>β

1/α</sub>

), and the second β

-axis/α

-axis current difference (di<sub>β

2/α

1</sub>) are computed based on equations;

di<sub>α

1/β</sub>

=i_α

(k+1)−

k₁i_α

(k)−

k₂i_β

(k),

di<sub>α

2/β

1</sub>=i_α

(k+2)−

k₁i_α

(k+1)−

k₂i_β

(k+1),

di<sub>β

1/α</sub>

=i_β

(k+1)−

k₁i_β

(k)+k₂i_α

(k),

di<sub>β

2/α

1</sub>=i_β

(k+2)−

k₁i_β

(k+1)+k₂i_α

(k+1),

respectively, where k₁ is a diagonal element of the dimensionless gain matrix K(k) and k₂ is a sub-diagonal element of the dimensionless gain matrix K(k), i_α

(k) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at the first sample point, i_α

(k+1) is a two-phase a-axis component of the stationary reference frame feedback stator current sample at a second sample point, i_α

(k+2) is a two-phase α

-axis component of the stationary reference frame feedback stator current sample at a third sample point, i_β

(k) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the first sample point, i_β

(k+1) is two-phase β

-axis component of the stationary reference frame feedback stator current sample at the second sample point, and i_β

(k+2) is a two-phase β

-axis component of the stationary reference frame feedback stator current sample at the third sample point.

19. A system according to claim 11, further comprising:

an inverter module comprising switches;

a fault detection and confirmation module configured to detect that a fault condition has occurred, and generate a command to enter a three-phase short operating mode; and

an open/short controller module configured to receive the command and to generate control signals that cause switches of the inverter module to be configured in the three-phase short operating mode; and

an abc reference frame-to-α

β

reference frame transformation module configured to sample three-phase stationary reference frame feedback stator currents (i_sa . . . i_sc) and to transform the samples of the three-phase stationary reference frame feedback stator currents (i_sa . . . i_sc) into two-phase stationary reference frame feedback stator current samples (i_α

(k), i_β

(k)), and wherein the electrical angular speed estimator module is configured to store the two-phase stationary reference frame feedback stator current samples (i_α

(k), i_β

(k)).

20. A controller for a permanent magnet machine, comprising:

an inverter module comprising switches;

a fault detection and confirmation module configured to detect that a fault condition has occurred, and generate a command to enter a three-phase short operating mode; and

an open/short controller module configured to receive the command and to generate control signals that cause switches of the inverter module to be configured in the three-phase short operating mode;

an abc reference frame-to-α

β

reference frame transformation module configured to sample three-phase stationary reference frame feedback stator currents (i_sa . . . i_sc) and to transform the samples of the three-phase stationary reference frame feedback stator currents (i_sa . . . i_sc) into two-phase stationary reference frame feedback stator current samples (i_α

(k), i_β

(k)); and

an electrical angular speed estimator module configured to compute an estimated electrical angular speed (ω

_est(k)) of the permanent magnet machine based on;

three or more two-phase stationary reference frame feedback stator current samples (i_α

(k), i_α

(k+1), i_α

(k+2), i_β

(k), i_β

(k+1), i_β

(k+2)), and a dimensionless gain (K) that is computed based on a sampling time (T) and machine parameters.