Methods, systems and apparatus for controlling a multi-phase inverter

• US 8,575,879 B2
• Filed: 08/19/2011
• Issued: 11/05/2013
• Est. Priority Date: 08/19/2011
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Welchko, Brian A., Dai, Min
• Primary Examiner(s): Santana, Eduardo Colon
• Assistant Examiner(s): CARRASQUILLO, JORGE L
• Application Number:
  US13/214,042
• Publication Number:
  US 20130043816A1
• Time in Patent Office: 809 Days
• Field of Search: 318/400.21, 318/490, 318/812, 318/767, 318/727, 318/377, 318/802, 318/803, 318/804, 318/806, 318/616, 318/807, 318/565, 318/376, 318/139, 318/375, 318/801, 318/563, 702/58, 702/59, 361/23, 361/74, 361/76, 361/79, 361/84, 324/545, 324/546, 324/765.01
• US Class Current: 318/563
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02P 21/0085 specially adapted for high speeds, e.g. above nominal speed
• CPC Class Codes: H02P 2203/09 Motor speed determination based on the current and/or voltage without using a tachogenerator or a physical encoder
• CPC Class Codes: H02P 27/08 with pulse width modulation
• CPC Class Codes: H02P 3/22 by short-circuit or resistive braking

Abstract

Embodiments of the present invention relate to methods, systems, a machine-readable medium operable in a controller, and apparatus for controlling a multi-phase inverter that drives a multi-phase electric machine. When a sensor fault is detected, a phase current angle is computed based on the feedback stator currents, and used to estimate an angular velocity and an angular position of a rotor of the multi-phase electric machine. When the estimated angular velocity of the multi-phase electric machine is less than a transition angular velocity threshold, an open-circuit response can be applied at the multi-phase inverter by controlling all switches in the multi-phase inverter drive to be open. By contrast, when the estimated angular velocity is greater than the transition angular velocity threshold, a short-circuit response can be applied at the multi-phase inverter by controlling selected switches in the multi-phase inverter drive to connect all phases of the multi-phase inverter to a single bus (e.g., either the plus bus or the minus bus).

Claims

1. A method for controlling a multi-phase inverter that drives a multi-phase electric machine, the method comprising:

detecting a sensor fault of a sensor that is used for sensing at least one of a rotor position and a rotor angular velocity of the multi-phase electric machine;

after detecting the sensor fault;

estimating, based on feedback stator currents, angular velocity of a rotor of the multi-phase electric machine;

determining whether the estimated angular velocity is greater than a transition angular velocity threshold;

applying an open-circuit response at the multi-phase inverter when the estimated angular velocity of the multi-phase electric machine is less than the transition angular velocity threshold; and

applying a short-circuit response at the multi-phase inverter when the estimated angular velocity is greater than the transition angular velocity threshold.

2. A method according to claim 1, wherein the applying the open-circuit response comprises:

controlling all switches in the multi-phase inverter drive to be open.

3. A method according to claim 1, wherein the applying the short-circuit response comprises:

controlling selected switches in the multi-phase inverter drive to connect all phases of the multi-phase inverter to a single bus; and

controlling all other non-selected switches in the multi-phase inverter drive to be open such that the non-selected switches are not connected to the single bus.

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

after detecting the sensor fault and before estimating, applying the short-circuit response at the multi-phase inverter.

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

computing a phase current angle based on the feedback stator currents, and

wherein estimating comprises;

estimating, based on the phase current angle, the angular velocity of the rotor of the multi-phase electric machine and an angular position of the rotor of the multi-phase electric machine.

6. A method according to claim 5, further comprising:

determining, prior to computing the phase current angle, whether the magnitude of the feedback stator currents are either qualified or disqualified for computing the phase current angle, wherein the phase current angle is computed when the magnitude of the feedback stator currents are determined to be qualified and is not computed when the magnitude of the feedback stator currents are determined to be disqualified.

7. A method according to claim 5, further comprising:

determining, after estimating the angular velocity and the angular position of the rotor, whether the estimated angular position of the rotor is sufficiently accurate before determining whether the estimated angular velocity is greater than the transition angular velocity threshold.

8. A method according to claim 7, wherein determining, after estimating the angular velocity and the angular position of the rotor, whether the estimated angular position of the rotor is sufficiently accurate, comprises:

after estimating the angular velocity and the angular position of the rotor and before determining whether the estimated angular velocity is greater than the transition angular velocity threshold, determining a magnitude of an angular difference between the computed phase current angle and the estimated angular position of the rotor; and

determining whether the magnitude of the angular difference is less than an angular threshold (θ

_thresh); and

wherein the step of determining whether the estimated angular velocity is greater than the transition angular velocity threshold is performed only when the magnitude of the angular difference is less than the angular threshold.

9. A method according to claim 1, wherein the feedback stator currents comprise:

stationary reference frame feedback stator currents.

10. A method according to claim 1, wherein the transition angular velocity threshold is one of:

a fixed predetermined angular velocity and is defined based on parameters characteristic of the multi-phase electric machine; and

an adjusted predetermined angular velocity and is defined based on parameters characteristic of the multi-phase electric machine adjusted according to at least one of a temperature of the multi-phase electric machine and a voltage of a voltage source.

11. An apparatus, comprising:

a multi-phase inverter to drive a multi-phase electric machine;

a fault detector to indicate detection of a sensor fault of a sensor that is used for sensing at least one of a rotor position and a rotor angular velocity of the multi-phase electric machine, wherein the sensor is designed to provide at least one of an angular velocity signal indicative of the angular velocity of a rotor of a multi-phase electric machine, and an angular position signal indicative of the angular position of the rotor of the multi-phase electric machine; and

a controller operable, in response to receiving an indication from the fault detector that the sensor fault has been detected, to estimate angular velocity of a rotor of the multi-phase electric machine based on feedback stator currents, to determine whether the estimated angular velocity is greater than a transition angular velocity threshold, and to apply either;

an open-circuit response at the multi-phase inverter when the estimated angular velocity of the multi-phase electric machine is less than the transition angular velocity threshold;

or

a short-circuit response at the multi-phase inverter when the estimated angular velocity is greater than the transition angular velocity threshold.

12. An apparatus according to claim 11, wherein the open-circuit response is applied by controlling all switches in the multi-phase inverter drive to be open.

13. An apparatus according to claim 11, wherein the short-circuit response is applied by controlling selected switches in the multi-phase inverter drive to connect all phases of the multi-phase inverter to a single bus, and by controlling all other non-selected switches in the multi-phase inverter drive to be open such that the non-selected switches are not connected to the single bus.

14. An apparatus according to claim 11, wherein the controller is further operable to apply the short-circuit response at the multi-phase inverter after the sensor fault is defected and before the angular velocity of the rotor is estimated.

15. An apparatus according to claim 11, wherein the controller is further operable to compute a phase current angle based on the feedback stator currents, and

wherein the controller is further operable to estimate, based on the phase current angle, the angular velocity of the rotor of the multi-phase electric machine and an angular position of the rotor of the multi-phase electric machine.

16. An apparatus according to claim 15, wherein the controller is further operable, before the controller computes the phase current angle, to determine whether the magnitude of the feedback stator currents are either qualified or disqualified to compute the phase current angle,

wherein the phase current angle is computed when the magnitude of the feedback stator currents are determined to be qualified and is not computed when the magnitude of the feedback stator currents are determined to be disqualified.

17. An apparatus according to claim 15, wherein the controller is further operable, after the controller estimates the angular velocity and the angular position of the rotor and before the controller determines whether the estimated angular velocity is greater than the transition angular velocity threshold, to determine whether the estimated angular position of the rotor is sufficiently accurate.

18. An apparatus according to claim 17, wherein, after the controller estimates the angular velocity and the angular position of the rotor and before the controller determines whether the estimated angular velocity is greater than the transition angular velocity threshold, the controller is further operable to determine a magnitude of an angular difference between the computed phase current angle and the estimated angular position of the rotor, to determine whether the magnitude of the angular difference is less than an angular threshold (θ

_thresh), and to determine whether the estimated angular velocity is greater than the transition angular velocity threshold only when the magnitude of the angular difference is less than the angular threshold.

19. An apparatus according to claim 11, wherein the feedback stator currents comprise:

stationary reference frame feedback stator currents.

20. A non-transitory machine-readable medium comprising sets of instructions operable in a controller to cause the controller to perform operations in response to the controller receiving an indication that a sensor for sensing either a position or angular velocity of a rotor has faulted, the operations comprising:

estimating, based on feedback stator currents, angular velocity of a rotor of a multi-phase electric machine;

determining whether the estimated angular velocity is greater than a transition angular velocity threshold; and

generating control signals to cause either;

an open-circuit response to be applied at a multi-phase inverter when the estimated angular velocity of the multi-phase electric machine is less than the transition angular velocity threshold;

or

a short-circuit response to be applied at the multi-phase inverter when the estimated angular velocity is greater than the transition angular velocity threshold.