Turbine/alternator on a common shaft with an associated electrical system

• US 6,323,625 B1
• Filed: 07/14/1998
• Issued: 11/27/2001
• Est. Priority Date: 12/03/1996
• Status: Expired due to Fees

• Current Assignee: Ashman Technologies Company
• Original Assignee: Brij B. Bhargava
• Inventors: Bhargava, Brij B.
• Primary Examiner(s): Enad, Elvin
• Assistant Examiner(s): MEDLEY, PETER M
• Application Number:
  US09/115,308
• Time in Patent Office: 1,232 Days
• Field of Search: 322/10, 322/32, 318/140
• US Class Current: 322/32
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F02C 7/26 Starting; Ignition
• 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: F02C 7/275 Mechanical drives
• CPC Class Codes: F02N 11/04 the motors being associated with current generators
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 24/201 with screw threaded or notch engaging securing means
• CPC Class Codes: Y10T 24/202 Resiliently biased

Abstract

An electrical system for a turbine/alternator comprising a gas driven turbine and permanent magnet alternator rotor rotating on a common shaft and comprising an inverter circuit connected either to an AC output circuit or the stator windings of the alternator. A control circuit during start-up mode connects the inverter circuit to the stator windings of the alternator and during the power generation mode it switches and connects the inverter circuit to the AC output circuit. Thus, during the start-up mode, the alternator functions as a motor to raise the speed of the turbine to a safe ignition speed and in the power generation mode the system provides power through the AC output circuit, electrical power having a frequency and voltage unrelated to the rotational speed of the turbine/alternator.

Claims

1. A high speed turbine/alternator system for generation of electric power, comprising:

a gas driven turbine system;

an alternator having a permanent magnet rotor and a stator;

a shaft which is coupled in common to said turbine system and said rotor;

an m-pole permanent magnet system carried by said rotor;

an annular retention system arranged over said rotor to oppose centripetal force and retain said magnet system in place;

a high permeability core included in said stator;

a slot system defined by said core;

an n-phase distributed winding carried in said slot system; and

an electrical system;

wherein electromagnetic interaction that generates n-phase AC signals in response to rotation of said rotor by said turbine system is limited to said m-pole permanent magnet system and said n-phase distributed winding;

and wherein said electrical system is configured to facilitate rotation of said rotor in a start-up operational mode of said turbine/alternator system and to extract said electric power from said n-phase AC signals during a power generation operational mode of said turbine/alternator system.

2. The turbine/alternator system according to claim 1 in which said shaft forces said permanent magnet rotor to rotate at the same speed as said gas driven turbine system at any given time, wherein said permanent magnets are formed of a rare earth material, and said electrical system includes:

a) an AC output circuit;

b) an inverter circuit connected to said AC output circuit;

c) a first contactor for connecting said inverter circuit to said n-phase distributed windings;

d) a DC bus connected to said inverter circuit;

e) a rectifier connected between said n-phase distributed windings and said DC bus;

f) a power supply circuit connected to said DC bus, operational during said start-up operational mode;

g) a driver connected to cause switching of said inverter circuit;

h) a signal generator driven by signals derived from the rotation of said shaft;

i) an open loop waveform generator;

j) a second contactor for connecting a selected one of said signal generator and said open loop waveform generator to said driver; and

k) a control circuit for, during said start-up operational mode, switching said first contactor to connect said inverter circuit to said n-phase distributed windings and switching said second contactor to connect said signal generator to said driver and during said power generation operational mode switching said first contactor to disconnect said inverter circuit from said n-phase distributed windings and switching said second contactor to connect said open loop waveform generator to said driver;

whereby during said start-up operational mode, said alternator functions as a motor to raise the speed of said turbine system to a safe ignition speed and in said power generation operational mode, said AC output circuit delivers said electric power with a frequency and voltage unrelated to the rotational speed of said shaft.

3. The turbine/alternator system according to claim 2, wherein said n-phase distributed winding and said electrical system are both a selected one of single-phase or poly-phase circuits.

4. The turbine/alternator system according to claim 2, wherein said electrical system includes microprocessors to control, monitor, and communicate all system functions and parameters for its normal operation.

5. The turbine/alternator system according to claim 2, wherein said power supply circuit comprises a battery and a boost circuit to provide to said DC bus a voltage between 0 volts and that voltage required by said inverter to raise the turbine/alternator speed to safe turbine ignition speed.

6. The turbine/alternator system according to claim 5, wherein said power supply circuit comprises a frequency pulse width modulator for driving said boost circuit.

7. The turbine/alternator system according to claim 6, wherein said control circuit controls the duty cycle of said pulse width modulator to regulate the voltage to said DC bus.

8. The turbine/alternator system according to claim 6, wherein said power supply circuit comprises a battery, a charger circuit and a constant frequency pulse width modulator for driving said charger circuit and adjusting the duty cycle of said pulse width modulator to control the charging voltage of said battery.

9. The turbine/alternator system according to claim 2, wherein said drive is a pulse width modulated driver.

10. The turbine/alternator system according to claim 2, wherein said power supply circuit comprises a battery and a step down circuit for recharging said battery during said power generation operational mode.

11. The turbine/alternator system according to claim 2, wherein said control circuit utilizes a Digital Signal Processor control in conjunction with an IGBT converter to control, monitor, and communicate all system functions and parameters for its normal operation.

12. The turbine/alternator system of claim 1, wherein said annular retention system includes a composite sleeve positioned about said magnet system.

13. The turbine/alternator system of claim 1, wherein said annular retention system includes a non-magnetic ring positioned about said magnet system.

14. The turbine/alternator system of claim 1, wherein said core is comprised of electrical steel laminations.

15. The turbine/alternator system of claim 1, wherein said alternator includes a selected one of a liquid and a gas cooling system configured to cool said stator.

16. A high-speed turbine/alternator system for generation of electric power, comprising:

a shaft;

a turbine system directly fixed to said shaft;

an alternator that has a stator that carries an n-phase distributed winding and further has a rotor that is directly fixed to said shaft wherein said rotor includes;

a) an m-pole permanent magnet system, and

b) an annular retention system arranged over said rotor to oppose centripetal force and retain said magnet system in place;

and wherein electromagnetic interaction that generates n-phase AC signals in response to rotation of said rotor by said turbine system is limited to said m-pole permanent magnet system and said n-phase distributed winding; and

an electrical system configured to facilitate rotation of said rotor in a start up operational mode of said turbine/alternator system and to extract said electric power from said n-phase AC signals during a power generation operational mode of said turbine/alternator system.

17. The turbine/alternator system of claim 16, wherein said annular retention system includes a composite sleeve positioned about said magnet system.

18. The turbine/alternator system of claim 16, wherein said annular retention system includes a non-magnetic ring positioned about said magnet system.

19. The turbine/alternator system of claim 16, wherein said magnet system includes rare earth magnets.

20. The turbine/alternator system of claim 16, wherein said stator includes a low loss, high permeability core.

21. The turbine/alternator system of claim 20, wherein said core defines a slot system and said n-phase distributed winding is carried in said slot system.

22. The turbine/alternator system of claim 20, wherein said core is comprised of electrical steel laminations.

23. The turbine/alternator system of claim 16, wherein said m-pole magnet system is a 4-pole magnet system and said n-phase distributed winding is a 3-phase distributed winding.

24. The turbine/alternator system of claim 16, wherein said alternator includes a selected one of a liquid and a gas cooling system configured to cool said stator.

25. The turbine/alternator system of claim 16, wherein said turbine system is a gas turbine driven system.

26. The turbine/alternator system of claim 16, wherein said electrical system includes:

a rectifier that rectifies said n-phase AC signals into a rectified signal;

a waveform generator;

an inverter that converts said rectified signal into said electric power in response to said waveform generator;

a filter system coupled to said inverter for filtering said electric power;

a DC power source; and

a contactor system configured to decouple at least a portion of said filter system from said inverter, couple said DC power source to said inverter and couple said inverter to said n-phase distributed winding during said start-up operational mode.