Granted Patent B1

US 7,282,886 · App. 11/462,596 · Granted Oct 16, 2007

Abstract

Claims (136)

1. A method for controlling a permanent magnet motor, the method comprising the steps of:

adjusting a first current command in response to a voltage error to produce a first adjusted current, the voltage error derived from a second current command during a voltage saturation of the permanent magnet motor;

limiting each of the first adjusted current and the second current command below a maximum current;

converting the first adjusted current to a first potential;

converting the second current command to a second potential; and

supplying the first and second potentials to the permanent magnet motor.

2. A method according to claim 1 , wherein said limiting step comprises:

limiting the first adjusted current below a first current limit; and

limiting the second current command below a second current limit, the second current limit derived from the first adjusted current and the maximum current.

3. A method according to claim 1 , wherein said limiting step comprises:

limiting the first adjusted current to a first predetermined maximum current to produce a first limited current; and

limiting the second current command between

I

s_max

2

-

(

i

ds_m

r

*

)

2

⁢

⁢

and

⁢

-

I

s_max

2

-

(

i

ds_m

r

*

)

2

,

wherein I s — max is a maximum stator current and i r* ds — m is the first limited current.

4. A method according to claim 1 , wherein the permanent magnet motor has a voltage limitation, and wherein said step of adjusting the first current command comprises:

determining a correction factor ω r L s (v r* qs −v r* qs );

low pass filtering the correction factor to produce a filtered value;

applying a predetermined control gain to the filtered value to produce a current adjustment; and

subtracting the current adjustment from the first current command to produce the first adjusted current;

wherein ω r is a rotor speed of the permanent magnet motor, L s is a machine per phase inductance, v r* qs is a q-axis reference voltage command derived from the second current command, and v r qs is a q-axis reference voltage derived from an application of the voltage limitation to v r* qs .

5. A method according to claim 1 , wherein the permanent magnet motor has a voltage limitation, and wherein said step of converting the first adjusted current comprises:

converting the first adjusted current to a first voltage command; and

limiting the first voltage command below the maximum potential to produce the first potential.

6. A method according to claim 1 , wherein the permanent magnet motor has a voltage limitation, and wherein said step of converting the second current command comprises:

converting the second current command to a second voltage command; and

limiting the second voltage command below the maximum potential to produce the second potential.

7. A method according to claim 6 , wherein said step of adjusting comprises determining the voltage error from a difference between the second voltage command and the second potential.

8. A method for controlling a permanent magnet motor, the method comprising the steps of:

adjusting a first current command in response to a first voltage error to produce a first adjusted current, the first voltage error derived from a second current command during a voltage saturation of the permanent magnet motor;

adjusting the second current command in response to a second voltage error to produce a second adjusted current, the second voltage error derived from the first current command during the voltage saturation of the permanent magnet motor;

limiting each of the first adjusted current and the second adjusted current below a maximum current;

converting the first adjusted current to a first potential;

converting the second adjusted current to a second potential; and

supplying the first and second potentials to the permanent magnet motor.

9. A method according to claim 8 , wherein said limiting step comprises:

limiting the first adjusted current below a first current limit; and

limiting the second adjusted current below a second current limit, the second current limit derived from the first current limit and the maximum current.

10. A method according to claim 8 , wherein said limiting step comprises:

limiting the first adjusted current below a first predetermined maximum current to produce a first limited current reference; and

limiting the second adjusted current between

I

s_max

2

-

(

i

ds_m

′

+

)

2

⁢

⁢

and

⁢

-

I

s_max

2

-

(

i

ds_m

r

+

)

2

,

wherein I s — max is the maximum current and i r* ds — m is the first limited current reference.

11. A method according to claim 8 , wherein the permanent magnet motor has a voltage limitation, and wherein the method further comprises prior to said step of adjusting the first current command:

producing a first voltage command for the second current command; and

determining the first voltage error from the first voltage command and the maximum voltage.

12. A method according to claim 8 , wherein the permanent magnet motor has a maximum voltage, and wherein said step of adjusting the first current command comprises:

determining a correction factor ω r L s (v r* qs −v r* qs );

low pass filtering the correction factor to produce a filtered value;

applying a predetermined control gain to the filtered value to produce a current adjustment; and

subtracting the current adjustment from the first current command to produce the first adjusted current;

wherein ω r is a rotor speed of the permanent magnet motor, L s is a machine per phase inductance, v r* qs is a q-axis reference voltage command derived from the second current command, and v r qs is a q-axis reference voltage derived from the maximum voltage and v r* qs .

13. A method according to claim 8 , wherein the permanent magnet motor has a maximum voltage, and wherein said step of adjusting the second current command comprises:

producing a second voltage command from the first current command; and

determining the second voltage error from the second voltage command and the maximum voltage.

14. A method according to claim 8 , wherein the permanent magnet motor has a maximum voltage, and wherein said step of adjusting the second current command comprises:

determining a correction factor ω r L s (v r* ds −v r* ds );

band pass filtering the correction factor to produce a filtered value;

applying a predetermined control gain to the filtered value to produce a current adjustment, and

subtracting the current adjustment from the second command current to produce the second adjusted current;

wherein ω r is a rotor speed of the permanent magnet motor, L s is a machine per phase inductance, v r* ds is a d-axis reference voltage command derived from the second command current, and v r ds is a d-axis reference voltage derived from the maximum voltage and v r* ds .

15. A method according to claim 8 , wherein the permanent magnet motor has a voltage limitation, and wherein the method further comprises:

converting the first adjusted current to a first voltage reference command;

converting the second adjusted current to a second voltage reference command; and

limiting each of the first and second voltage reference commands to the maximum voltage.

16. A control system for regulating an input voltage to a permanent magnet motor having a saturation current, the controller comprising:

a first current compensation module configured to:

subtract a first error from a first current command to produce a first adjusted current; and

limit said first adjusted current to a first maximum current to produce a first limited current;

a second current compensation module configured to limit a second current command to a second maximum current to produce a second limited current, said second maximum current derived from said first maximum current and said saturation current; and

a transformation module coupled to said first and second current compensation modules for converting said first limited current to a first input voltage and for converting said second limited current to a second input voltage, said first error produced while converting said second limited current to said second input voltage.

17. A control system according to claim 16 , wherein said first current compensation module comprises:

a low pass filter receiving said first error and producing a filtered signal;

a gain module coupled to said low pass filter for applying a control gain to said filtered signal; and

a summer coupled to said amplifier for comparing said first current command with said.

18. A control system according to claim 16 , wherein said second current compensation module comprises a summer for adding said second limited current with a second error, said second error produced while converting said first limited current to said first input voltage.

19. A control system according to claim 18 , wherein said second current compensation module further comprises:

a band pass filter receiving said second error and producing a filtered signal; and

a gain module coupled to said band pass filter for applying a control gain to said filtered signal.

20. A control system according to claim 16 , wherein said transformation module comprises a voltage limitation module configured to:

receive first and second voltage commands, said first voltage command derived from said first limited current, said second voltage command derived from said second limited current;

limit said first voltage command to produce said first input voltage, said second error being a difference between said first voltage command and said first input voltage; and

limit said second voltage command to produce said second input voltage, said first error being a difference between said second voltage command and said second input voltage.

Assignments (12)