Method and systems for an engine starter/generator

• US 8,030,788 B2
• Filed: 12/31/2008
• Issued: 10/04/2011
• Est. Priority Date: 12/31/2008
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Huang, Hao, Xu, Longya, Karipides, David Dimitri, Abbas, Mohamed
• Primary Examiner(s): ZARROLI, MICHAEL C
• Application Number:
  US12/347,616
• Publication Number:
  US 20100164428A1
• Time in Patent Office: 1,007 Days
• Field of Search: None
• US Class Current: 290/31
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F02C 7/268 Starting drives for the rotor , acting directly on the rotor of the gas turbine to be started
• CPC Class Codes: F02N 11/04 the motors being associated with current generators
• CPC Class Codes: F02N 11/0859 specially adapted to the type of the starter motor or integrated into it
• CPC Class Codes: F02N 15/00 Other power-operated starting apparatus; Component parts, details, or accessories, not provided for in, or of interest apart from groups F02N5/00 - F02N13/00
• CPC Class Codes: F02N 2011/0888 DC/DC converters
• CPC Class Codes: F02N 2011/0896 Inverters for electric machines, e.g. starter-generators
• CPC Class Codes: F02N 2250/08 Lubrication of starters; Sealing means for starters
• CPC Class Codes: H02P 21/24 Vector control not involving the use of rotor position or rotor speed sensors
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

A method and system for an engine starter/generator is provided. The starter/generator system includes a three phase squirrel cage induction machine, a three phase inverter/converter electrically coupled to the three phase squirrel cage induction machine. The starter/generator system also includes a bidirectional DC-DC converter electrically coupled to the three phase inverter/converter, and a digital control board configured to sensorlessly determine a rotor angle from a plurality of phase currents to the induction machine during a start mode. During the start mode, logic in the digital control board configures the starter/generator system into a combination of an induction motor, a three phase DC-AC inverter, and a DC-DC boost converter, and during a generate mode, the logic in the digital control board configures the starter/generator system into a combination of an induction generator, a three phase AC-DC converter, and a DC-DC buck converter.

Claims

1. A starter/generator system comprising:

a three phase squirrel cage induction machine; and

a first three-phase inverter/converter/controller (ICC) unit operatively coupled to said three phase squirrel cage induction machine through a first electrical path, said ICC comprising;

a three phase inverter/converter electrically coupled to said three phase squirrel cage induction machine;

a bidirectional DC-DC converter electrically coupled to said three phase inverter/converter; and

a digital control board configured to sensorlessly determine a rotor angle from a plurality of phase currents to the induction machine during a start mode;

wherein during a start mode, logic in said digital control board configures said starter/generator system into a combination of an induction motor, a three phase DC-AC inverter, and a DC-DC boost converter, and during a generate mode, the logic in said digital control board configures said starter/generator system into a combination of an induction generator, a three phase AC-DC converter, and a DC-DC buck converter.

2. A starter/generator system in accordance with claim 1 wherein commutation of the three phase inverter/converter is determined using a sensorless mechanism.

3. A starter/generator system in accordance with claim 1 wherein said DC-DC boost converter is configured to boost an input power from a first voltage value to a second voltage value, the second value being greater in magnitude than the first value.

4. A starter/generator system in accordance with claim 1 wherein said digital control board is configured to:

measure two of the three phase currents, i_a and i_b of the induction motor; and

convert the per phase quantities of phase currents, i_a and i_b into a current i_d and a current i_q, where i_d is the current aligning with the rotor flux linkage i_q is the current perpendicular to the rotor flux linkage;

control the field of the induction motor using i_d; and

control the torque of the induction motor using i_q.

5. A starter/generator system in accordance with claim 4 wherein said digital control board is further configured to determine a rotor angle of the induction motor using the currents, i_a and i_b, and a first voltage command, v*_α

and a second voltage command v*_β

.

6. A starter/generator system in accordance with claim 4 wherein said digital control board is further configured to determine a rotor angle of the induction motor using a flux linkage method.

7. A starter/generator system in accordance with claim 1 further comprising a second three-phase inverter/converter/controller (ICC) unit operatively coupled to said three phase squirrel cage induction machine through a second electrical path parallel to said first electrical path, said second ICC comprising:

a three phase inverter/converter electrically coupled to said three phase squirrel cage induction machine;

a bidirectional DC-DC converter electrically coupled to said three phase inverter/converter; and

a digital control board configured to sensorlessly determine a rotor angle from a plurality of phase currents to the induction machine during a start mode.

8. A starter/generator system in accordance with claim 1 wherein digital control board is configured to determine the rotor angle by integrating a summation of an estimated rotor speed and a slip speed.

9. A starter/generator system in accordance with claim 1 wherein digital control board is configured to determine a slip speed from an output of the output voltage regulator.

10. A starter/generator system in accordance with claim 1 wherein said digital control board is configured to convert a first preset voltage command v*_d and a second preset voltage command v*_q using the rotor angle to respective voltage commands to gate said AC-DC converter.

11. A method of controlling an engine starter/generator system for starting an engine and generating power using the engine, said method comprising:

during a start mode;

boosting an input voltage using a DC-DC converter;

inverting the boosted DC voltage into a three phase AC output that drives an induction motor configured to rotate the engine;

measuring two of the three phase currents, i_a and i_b;

converting phase currents, i_a and i_b into i_d and i_q, where i_d is the current aligning with the rotor flux linkage and i_q is the current perpendicular to the rotor flux linkage;

controlling a field of an induction machine of the starter/generator system using i_d;

controlling a torque of an induction machine of the starter/generator system using i_q;

during a generate mode;

applying a three phase output of the induction machine to the input of a the three phase converter to generate a three phase AC voltage;

converting the three phase AC voltage into a DC voltage at a first voltage magnitude greater than a predetermined output voltage magnitude of the starter/generator system;

bucking the DC voltage down to the predetermined output voltage magnitude of the starter/generator system using a cascaded DC-DC converter.

12. A method in accordance with claim 11 further comprising determining a rotor angle by integrating a summation of an estimated rotor speed and a slip speed wherein the slip speed is the output of an output voltage regulator.

13. A method in accordance with claim 11 further comprising converting a first preset voltage command v*_d and a second preset voltage command v*_q using the rotor angle to respective voltage commands to gate said AC-DC converter.

14. A method in accordance with claim 11 further comprising gating the DC-DC converter using a digital control board.

15. A method in accordance with claim 11 wherein converting phase currents, i_a and i_b into i_d and i_q, comprises converting phase currents, i_a and i_b into i_d and i_q, using a flux linkage position of a rotor of the induction machine.

16. A method in accordance with claim 11 further comprising sensorlessly determining a position of a rotor of the induction machine using the currents, i_α

and i_β

, and voltage commands, v*_α

and v*_β

by a flux linkage method.