Power factor control for floating frame controller for sensorless control of synchronous machines

• US 20070040524A1
• Filed: 08/17/2005
• Published: 02/22/2007
• Est. Priority Date: 08/17/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Sarlioglu, Bulent, Huggett, Colin
• Granted Patent: US 7,495,404 B2
• Time in Patent Office: Days
• US Class Current: 318/438
• CPC Class Codes: H02P 21/00 Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
• CPC Class Codes: H02P 21/0089 using field weakening
• 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

A system and method of controlling the power factor for providing either unity, leading or lagging results for the sensorless control of synchronous machines. The system and method provides an estimated angle of the phase current Park vector and uses a floating synchronous reference frame that is shifted from the estimated angle of the phase current Park vector by an angle β to allow the active control and change of the power factor during operation for applications such as producing reluctance torque of a salient pole synchronous machine during Main Engine Start (MES), and field weakening for Environmental Control Systems (ECS) and MES applications.

Claims

1. A method for actively controlling and changing a power factor during operation of a synchronous machine, the method comprising the steps of:

generating a floating synchronous reference frame;

providing an estimated angle of a phase current Park vector; and

shifting said floating synchronous reference frame from the estimated angle of the phase current Park vector by an angle beta (β

) to provide coordinate transformation for a controller to drive a synchronous machine.

2. A method for actively controlling and changing a power factor as claimed in claim 1, further comprising the step of:

generating said estimated angle of the phase current Park vector of the motor phase current from a Park vector of motor phase current in stationary reference frame.

3. A method for actively controlling and changing a power factor as claimed in claim 2, further comprising the step of:

multiplying said floating synchronous reference frame voltage Park vector command by an exponential function of said estimated angle of the phase current Park vector minus said beta angle (β

) to shift said floating reference frame from an estimated angle of a phase current Park vector by said beta angle (β

) to obtain the voltage Park vector command in stator reference frame.

4. A method for actively controlling and changing a power factor as claimed in claim 3, further comprising the step of:

multiplying said shifted floating reference frame voltage Park vector command by e<sup>+j(θ

est−

β

)</sup> to generate a stator reference frame voltage command imposed to a motor, wherein θ

_est is the estimated angular position of the current Park vector.

5. A method for actively controlling and changing a power factor as claimed in claim 4, wherein said beta angle (β

) is the current Park vector in floating reference frame.

6. A method for actively controlling and changing a power factor as claimed in claim 2, further comprising the step of:

multiplying said stationary reference frame current Park vector feedback by an exponential function of said estimated angle of the phase current Park vector minus said beta angle (β

) to shift said stator reference frame from an estimated angle of a phase current Park vector by said beta angle (β

) to obtain the current Park vector feedback in floating reference frame.

7. A method for actively controlling and changing a power factor as claimed in claim 6, further comprising the step of:

multiplying said shifted stationary reference frame current Park vector command by e<sup>−

j(θ

est−

β

)</sup> to generate a floating reference frame current feedback used in the controller, wherein θ

_est is the estimated angular position of the current Park vector.

8. A method of controlling a power factor at either unity, leading or lagging for the sensorless control of synchronous machines, comprising the steps of:

commanding a desired power factor (PF) of either a leading, lagging or unity value using a negative, positive, or unity command;

comparing said desired power factor (PF) with an actual power factor ((PF)fdbk) at a first adder, said comparison producing a power factor (PF) error value;

operating upon said power factor (PF) error value by a first PI regulator, wherein an output of said first PI regulator is an angle command of a current Park vector in floating reference frame provided to a floating frame controller; and

operating upon said angle command of said current Park vector in floating reference frame by said floating frame controller to provide a stator reference frame voltage command, wherein said stator reference frame voltage command is provided using a position estimate and said floating reference frame is shifted by an angle beta (β

).

9. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 8, further comprising the steps of:

decomposing said command of said current Park vector into v- and u-components of said Park vector in floating reference frame;

comparing said v- and u-components of said Park vector in floating reference frame at a second and third adder, respectively, with a corresponding feedback in floating reference frame to generate current errors;

operating upon said current errors by second and third PI regulators, wherein an output of said second and third PI regulators comprises a voltage value; and

summing said outputs of said second and third PI regulators with decoupling of crosscoupling terms to generate decoupled v- and u-voltages.

10. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 9, further comprising the step of:

operating upon said decoupled v- and u-voltages to generate a floating synchronous reference frame voltage Park vector command.

11. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 10, wherein the step of providing said stator reference frame voltage command further comprises the step of:

multiplying said floating synchronous reference frame voltage Park vector command by said angular position estimate of the current vector minus said beta angle (β

) to shift said floating reference frame from an estimated angle of a phase current Park vector by said beta angle (β

).

12. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 9, further comprising the steps of:

crossmultiplying the Park vector of motor phase current in stationary reference frame by e<sup>jθ

est</sup> and comparing the product with a zero value at a fourth adder to produce a cross product error value; and

operating upon said cross product error value by a fourth PI regulator, wherein an output of said fourth PI regulator is an angular velocity estimation of a current Park vector.

13. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 12, further comprising the step of:

adding said angular velocity estimation to an initial angular velocity ω

₀ at a fifth adder to generate an estimated angular velocity signal ω

_est.

14. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 13, further comprising the step of:

integrating said estimated angular velocity signal ω

_est for generating said position estimate of the current Park vector and establishing a floating reference frame by shifting the estimated angle of the stationary reference frame Park vector by the angle command of the current Park vector in the floating reference frame.

15. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 8, wherein said step of generating said stator reference voltage command using said position estimate further comprises the steps of:

measuring at least two motor phase currents;

determining a stationary reference frame current Park vector based on said motor phase currents;

estimating an angular velocity of the stationary reference frame current Park vector;

estimating an angle of the stationary reference frame current Park vector;

establishing a floating reference frame by shifting the estimated angle of the stationary reference frame Park vector by the angle command of the current Park vector in the floating reference frame, wherein the floating reference frame is shifted from the estimated angle of the phase current Park vector by the angle beta (β

);

transforming the stationary reference frame current Park vector into a floating reference frame current Park vector; and

generating a decoupled voltage command based on the floating reference frame current Park vector and said estimated angular velocity.

16. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 12, wherein said step of generating said stator reference frame voltage Park vector command using said position estimate comprises the steps of:

delivering an initial voltage command to said motor;

measuring at least two phase currents in said motor;

constructing a stationary reference frame current Park vector based on said phase currents;

transforming said stationary reference frame current Park vector into a floating reference frame current Park vector;

comparing a u-axis component of said floating reference frame current Park vector to a predetermined value;

using a PI regulator to drive said u-axis current towards said predetermined value;

forcing said output to be zero if an output of said fourth PI regulator is negative;

adding an initial low frequency to said output of said fourth PI regulator;

estimating the velocity and angle of the stationary reference frame current Park vector based on the output of said fourth PI regulator; and

modifying the voltage command based on the output of said fourth PI regulator.

17. A method of controlling a power factor for the sensorless control of synchronous machines as claimed in claim 16, wherein said predetermined value is zero.

18. An apparatus for controlling a power factor at either unity, leading or lagging for the sensorless control of synchronous machines, comprising:

a first adder for receiving a control command for a desired power factor (PF) of either a leading, lagging or unity value, said first adder further configured for comparing said desired power factor (PF) with an actual power factor ((PF)fdbk), said comparison producing a power factor (PF) error value;

a first PI regulator for operating upon said power factor (PF) error value, wherein an output of said first PI regulator is an angle command of said current Park vector in floating reference frame provided to a floating frame controller; and

a floating frame controller for operating upon said angle command of said current Park vector in floating reference frame to provide a stator reference frame voltage command, wherein said stator reference frame voltage command is provided using a position estimate and said floating reference frame is shifted by an angle beta (β

).

19. An apparatus for controlling a power factor for the sensorless control of synchronous machines as claimed in claim 18, wherein said apparatus further comprises:

a second and third adder for comparing said current Park vector in floating reference frame with a corresponding feedback in floating reference frame to generate current errors, wherein said current Park vector is decomposed into v- and u-components of said Park vector in floating reference frame;

second and third PI regulators for operating upon said current errors, wherein an output of said second and third PI regulators comprises a voltage value; and

a summer for summing said outputs of said second and third PI regulators with decoupling of crosscoupling terms to generate decoupled v- and u-voltages.

20. An apparatus for controlling a power factor for the sensorless control of synchronous machines as claimed in claim 19, wherein said apparatus further comprises:

a function block for operating upon said decoupled v- and u-voltages to generate a floating synchronous reference frame voltage Park vector command;

a multiplier for crossmultiplying said floating synchronous reference frame voltage Park vector command by said angular position estimate of the current vector minus said beta angle (β

) to shift said floating reference frame from an estimated angle of a phase current Park vector by said beta angle (β

) to generate said stator reference frame voltage command;

a multiplier for crossmultiplying at least one Park vector of a motor phase current in stationary reference frame by e<sup>jθ

est</sup>;

a fourth adder for comparing the product with a zero value to produce a cross product error value;

a fourth PI regulator for operating upon said cross product error value, wherein an output of said fourth PI regulator is an angular estimation of a current vector; and

a fifth adder for adding said angular estimation to an initial angular velocity ω

₀ to generate an estimated angular velocity signal ω

_est.