Controller and method for minimizing phase advance current

• US 8,698,433 B2
• Filed: 08/09/2010
• Issued: 04/15/2014
• Est. Priority Date: 08/10/2009
• Status: Active Grant

• Current Assignee: Copeland Corporation LLC (Emerson Electric Company)
• Original Assignee: Emerson Climate Technologies Incorporated (Emerson Electric Company)
• Inventors: Green, Charles E.
• Primary Examiner(s): Chan, Kawing
• Application Number:
  US12/852,619
• Publication Number:
  US 20110031919A1
• Time in Patent Office: 1,345 Days
• Field of Search: 318/400.01, 318/400.02, 318/432, 318/700
• US Class Current: 318/400.02
• CPC Class Codes: F25B 49/025 Motor control arrangements
• CPC Class Codes: H02M 1/0085 Partially controlled bridges
• CPC Class Codes: H02M 1/4233 using a bridge converter comprising active switches
• CPC Class Codes: H02P 21/0089 using field weakening
• CPC Class Codes: H02P 21/06 Rotor flux based control involving the use of rotor position or rotor speed sensors
• CPC Class Codes: H02P 2201/15 Power factor Correction [PFC] circuit generating the DC link voltage for motor driving inverter motor power factor control H02P23/26
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A current control module generates a voltage request based on a d-axis current (Idr) demand. A switching control module controls a motor based on the voltage request and generates an out-of-volts (OOV) signal based on a comparison of the voltage request and an available voltage. An Idr injection module generates the Idr demand based on a direct current (DC) bus voltage, a rotational speed, and a demanded torque and selectively applies a first adjustment to the Idr demand. The Idr injection module identifies whether an improvement resulted from the first adjustment, wherein the improvement is identified based on at least one of (i) a measured current of the motor and (ii) the OOV signal. The Idr injection module selectively applies a second adjustment to the Idr demand based on whether the improvement is identified.

Claims

1. A system comprising:

a current control module that generates a voltage request based on a d-axis current (Idr) demand;

a switching control module that controls a motor based on the voltage request and that generates an out-of-volts (OOV) signal based on a comparison of the voltage request and an available voltage; and

an Idr injection module that;

generates the Idr demand based on a direct current (DC) bus voltage, a rotational speed, and a demanded torque;

selectively applies a first adjustment to the Idr demand;

identifies whether an improvement resulted from the first adjustment, wherein the improvement is identified when a measured current of the motor after the first adjustment is less than a measured current of the motor before the first adjustment; and

selectively applies a second adjustment to the Idr demand based on whether the improvement is identified.

2. The system of claim 1 wherein the improvement is identified when the OOV signal before the first adjustment is greater than a predetermined limit and the OOV signal after the first adjustment is less than the OOV signal before the first adjustment.

3. The system of claim 2 wherein the improvement is identified when all of the following are true:

(i) the OOV signal before the first adjustment is less than the predetermined limit, (ii) the OOV signal after the first adjustment is less than predetermined limit, and (iii) the measured current after the first adjustment is less than the measured current before the first adjustment.

4. The system of claim 1 wherein the Idr injection module:

determines a base demand;

selectively modifies an adjust value by applying the first and second adjustments; and

generates the Idr demand by adding the adjust value to the base demand.

5. The system of claim 4 wherein the Idr injection module determines the base demand from a lookup table based on the DC bus voltage, the rotational speed, and the demanded torque, and wherein the rotational speed is a commanded speed of the motor.

6. The system of claim 4 wherein:

when reset conditions are present, the Idr injection module resets the adjust value to zero, stores the rotational speed, and stores the DC bus voltage; and

the reset conditions include at least one of;

the OOV signal is greater than a first predetermined value,

a magnitude of a difference between the rotational speed and the stored value of the rotational speed is greater than a second predetermined value, and

a magnitude of a difference between the DC bus voltage and the stored value of the DC bus voltage is greater than a third predetermined value.

7. The system of claim 1 wherein the switching control module:

sets an OOV flag to a first value when the voltage request is greater than an upper limit based on the available voltage;

sets the OOV flag to a second value when the voltage request is less than the upper limit; and

generates the OOV signal based on an average of the OOV flag.

8. A system comprising:

a current control module that generates a voltage request based on a d-axis current (Idr) demand;

a switching control module that controls a motor based on the voltage request and that generates an out-of-volts (OOV) signal based on a comparison of the voltage request and an available voltage; and

an Idr injection module that;

generates the Idr demand based on a direct current (DC) bus voltage, a rotational speed, and a demanded torque;

selectively applies a first adjustment to the Idr demand;

identifies whether an improvement resulted from the first adjustment, wherein the improvement is identified based on at least one of (i) a measured current of the motor and (ii) the OOV signal; and

selectively applies a second adjustment to the Idr demand based on whether the improvement is identified,

wherein;

when the improvement is identified, the Idr injection module applies the second adjustment in a same direction as the first adjustment; and

when the improvement is not identified, the Idr injection module applies the second adjustment in an opposite direction of the first adjustment.

9. The system of claim 8 wherein when the improvement is not identified, the Idr injection module removes the first adjustment before applying the second adjustment.

10. A method comprising:

generating a d-axis current (Idr) demand based on a direct current (DC) bus voltage, a rotational speed, and a demanded torque;

generating a voltage request based on the Idr demand;

generating an out-of-volts (OOV) signal based on a comparison of the voltage request and an available voltage;

controlling a motor based on the voltage request;

selectively applying a first adjustment to the Idr demand;

identifying whether an improvement resulted from the first adjustment, wherein the improvement is identified when a measured current of the motor after the first adjustment is less than a measured current of the motor before the first adjustment; and

selectively applying a second adjustment to the Idr demand based on whether the improvement is identified.

11. The method of claim 10 wherein the improvement is identified when the OOV signal before the first adjustment is greater than a predetermined limit and the OOV signal after the first adjustment is less than the OOV signal before the first adjustment.

12. The method of claim 11 wherein the improvement is identified when all of the following are true:

(i) the OOV signal before the first adjustment is less than the predetermined limit, (ii) the OOV signal after the first adjustment is less than predetermined limit, and (iii) the measured current after the first adjustment is less than the measured current before the first adjustment.

13. The method of claim 10 further comprising:

determining a base demand;

selectively modifying an adjust value by applying the first and second adjustments; and

generating the Idr demand by adding the adjust value to the base demand.

14. The method of claim 13 further comprising determining the base demand from a lookup table based on the DC bus voltage, the rotational speed, and the demanded torque, and wherein the rotational speed is a commanded speed of the motor.

15. The method of claim 13 further comprising:

when reset conditions are present, resetting the adjust value to zero, storing the rotational speed, and storing the DC bus voltage; and

wherein the reset conditions include at least one of;

the OOV signal is greater than a first predetermined value,

a magnitude of a difference between the rotational speed and the stored value of the rotational speed is greater than a second predetermined value, and

a magnitude of a difference between the DC bus voltage and the stored value of the DC bus voltage is greater than a third predetermined value.

16. The method of claim 10 further comprising:

setting an OOV flag to a first value when the voltage request is greater than an upper limit based on the available voltage;

setting the OOV flag to a second value when the voltage request is less than the upper limit; and

generating the OOV signal based on an average of the OOV flag.

17. A method comprising:

generating a d-axis current (Idr) demand based on a direct current (DC) bus voltage, a rotational speed, and a demanded torque;

generating a voltage request based on the Idr demand;

generating an out-of-volts (OOV) signal based on a comparison of the voltage request and an available voltage;

controlling a motor based on the voltage request;

selectively applying a first adjustment to the Idr demand;

identifying whether an improvement resulted from the first adjustment, wherein the improvement is identified based on at least one of (i) a measured current of the motor and (ii) the OOV signal;

selectively applying a second adjustment to the Idr demand based on whether the improvement is identified;

when the improvement is identified, applying the second adjustment in a same direction as the first adjustment; and

when the improvement is not identified, applying the second adjustment in an opposite direction of the first adjustment.

18. A method of controlling a motor, the method comprising:

determining a base demand from a lookup table based on a direct current (DC) bus voltage, a commanded speed, and a demanded torque;

generating a d-axis current (Idr) demand by adding an adjust value to the base demand;

generating a voltage request based on the Idr demand;

setting an out-of-volts (OOV) flag to a first value when the voltage request is greater than an upper limit, wherein the upper limit is based on the DC bus voltage;

setting the OOV flag to a second value when the voltage request is less than the upper limit;

generating an OOV signal by averaging the OOV flag;

controlling a motor based on the voltage request;

selectively applying a first adjustment to the adjust value;

identifying whether an improvement resulted from the first adjustment, wherein the improvement is identified when at least one of;

both of the following are true;

(i) the OOV signal before the first adjustment is greater than a predetermined limit and (ii) the OOV signal after the first adjustment is less than the OOV signal before the first adjustment;

or

all of the following are true;

(i) the OOV signal before the first adjustment is less than the predetermined limit, (ii) the OOV signal after the first adjustment is less than predetermined limit, and (iii) a measured current after the first adjustment is less than the measured current before the first adjustment;

when the improvement is identified, applying a second adjustment to the adjust value in a same direction as the first adjustment;

when the improvement is not identified, applying the second adjustment to the adjust value in an opposite direction of the first adjustment; and

when reset conditions are present, resetting the adjust value to zero, storing the commanded speed, and storing the DC bus voltage,

wherein the reset conditions include at least one of;

the OOV signal is greater than a first predetermined value,

a magnitude of a difference between the commanded speed and the stored value of the commanded speed is greater than a second predetermined value, and

a magnitude of a difference between the DC bus voltage and the stored value of the DC bus voltage is greater than a third predetermined value.