Electrical generator employing rotary engine

• US 6,014,015 A
• Filed: 08/06/1998
• Issued: 01/11/2000
• Est. Priority Date: 08/08/1997
• Status: Expired due to Term

• Current Assignee: Alpha Technologies Services, Inc. (EnerSys)
• Original Assignee: Alpha Technologies Incorporated (EnerSys)
• Inventors: Kaiser, Fredrick, Skinner, Russell A. Sr., Thorne, Anthony R.
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): Medley, Peter
• Application Number:
  US09/130,639
• Time in Patent Office: 523 Days
• Field of Search: 307/23, 307/64, 322/14, 322/15, 322/33, 322/34, 322/27, 290/40 B, 290/40 C, 290/40 R
• US Class Current: 322/15
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator

Abstract

A system for generating electrical power signals from a fluid fuel source. The system comprises an engine and a generator. The engine burns the fuel and is connected to the generator such that the generator generates a raw power signal. An output stage generates an output power signal from the raw power signal. A control circuit controls the operation of the engine based on the output power signal. The control circuit further controls the operation of the engine based on an output current of the generator when this output current exceeds a current threshold level. The control circuit additionally controls the operation of the engine based on a temperature of the engine when the engine temperature exceeds a rated temperature level. The system thus generates sufficient power to supply a variable load but stays within an operating range defined by a rated power level and the rated temperature level.

Claims

1. A system for generating a power signal at an output bus from a fuel source comprising:

an engine having an output shaft, where the engine is connected to the fuel source such that the engine burns fuel to rotate the output shaft;

a generator having generator output terminals and an input shaft operatively connected to the output shaft such that rotation of the output shaft causes the generator to generate a raw power signal at the generator output terminals;

an output stage operatively connected between the generator output terminals and the output bus, where the output stage generates an output power signal from the raw power signal; and

an engine control portion for generating an engine control signal for controlling the engine, where the engine control portion generates the engine control signal to operate the engine

in a voltage control mode based on the output power signal in the absence of at least one predetermined fault state, and

in a fault control mode in a predetermined relationship to a fault parameter associated with the predetermined fault state when the predetermined fault state exists.

2. A system as recited in claim 1, in which the engine control portion controls the engine to maintain an output power of the system within a predetermined operating range.

3. A system as recited in claim 1, in which the engine control portion comprises:

a voltage control circuit for generating a voltage control signal corresponding to a voltage of the output power signal;

a current control circuit for generating a current control signal corresponding to the output current of the generator;

a temperature control circuit for generating a temperature control signal corresponding to the temperature of the engine;

a sensors control circuit for generating the engine control signal based on the voltage control signal, the current control signal, and the temperature control signal; and

engine control means for controlling the engine based on the engine control signal.

4. A system as recited in claim 3, in which the engine control means comprises:

a carburetor operatively connected between the fuel source and the engine for controlling the amount of fuel flowing to the engine; and

a servo motor operatively connected to the carburetor to open and close the carburetor based on the engine control signal.

5. A system as recited in claim 1, in which the engine is a rotary engine.

6. A system as recited in claim 1, in which the generator is a permanent magnet generator.

7. A system as recited in claim 1, in which the output stage comprises a rectifier and a filter.

8. A system as recited in claim 1, in which the engine control portion generates the engine control signal in at least one fault control mode selected from a group of fault control modes comprising a temperature control mode and a current control mode.

9. A system as recited in claim 8, in which

when the engine control portion operates in the temperature control mode, the engine control portion controls engine RPM in inverse relationship to the temperature of the engine;

and

when the engine control portion operates in the current control mode, the engine control portion controls engine RPM in inverse relationship to the output current of the generator.

10. A system as recited in claim 1, in which the predetermined fault state exists when the predetermined fault parameter does not fall within a predetermined fault range associated with the predetermined fault parameter.

11. A system as recited in claim 1, in which the predetermined fault state is selected from a group of predetermined fault states comprising a temperature fault state in which the temperature of the engine does not fall within a rated temperature range and a current fault state in which the output current of the generator does not fall within a rated current range.

12. A system as recited in claim 11, in which:

the temperature of the engine does not fall within the rated temperature range when the temperature of the engine exceeds a rated temperature level; and

the output current of the generator does not fall within the rated current range when the output current of the generator exceeds a current threshold level.

13. A method of generating a power signal at an output bus from a fuel source comprising:

providing an engine having an output shaft;

providing a generator having an input shaft and generator output terminals;

providing an output stage for conditioning electrical signals;

operatively connecting the engine to the fuel source;

operatively connecting the engine output shaft to the generator input shaft;

operatively connecting the output stage between the generator output terminals and the output bus;

operating the engine to burn fuel such that rotation of the output shaft causes the generator to generate a raw power signal at the generator output terminals;

passing the raw power signal through the output stage to obtain an output power signal at the output bus;

controlling the engine based on an engine control signal, where the engine control signal is generated to operate the engine

in a predetermined relationship to the output power signal in the absence of a predetermined fault state; and

in a predetermined relationship to a fault parameter associated with the predetermined fault state when the predetermined fault state exists.

14. A method as recited in claim 13, further comprising the step of controlling the engine to maintain an output power of the system within a predetermined operating range.

15. A method as recited in claim 13, in which the step of controlling the engine comprises the steps of:

generating a voltage control signal corresponding to a voltage of the output power signal;

generating a current control signal corresponding to the output current of the generator;

generating a temperature control signal corresponding to the temperature of the engine;

generating the engine control signal based on the voltage control signal, the current control signal, and the temperature control signal; and

controlling the engine based on the engine control signal.

16. A method as recited in claim 15, in which the step of controlling the engine comprises the steps of:

connecting a carburetor between the fuel source and the engine;

connecting a servo motor to the carburetor; and

operating the servo motor based on the engine control signal to open and close the carburetor and thereby regulate the amount of fluid flowing to the engine.

17. A method as recited in claim 13, in which the step of providing the engine comprises the step of providing a rotary engine.

18. A system as recited in claim 13, in which the step of providing the generator comprises the step of providing a permanent magnet generator.

19. A system as recited in claim 13, in which the step of providing the output stage comprises the steps of providing a rectifier and a filter.

20. A method as recited in claim 13, in which the predetermined fault state exists when the predetermined fault parameter does not fall within a predetermined fault range associated with the predetermined fault parameter.

21. A method as recited in claim 13, in which the predetermined fault state is selected from a group of predetermined fault states comprising a temperature fault state in which the temperature of the engine does not fall within a rated temperature range and a current fault state in which the output current of the generator does not fall within a rated current range.

22. A method as recited in claim 21, in which:

the temperature of the engine does not fall within the rated temperature range when the temperature of the engine exceeds a rated temperature level; and

the output current of the generator does not fall within the rated current range when the output current of the generator exceeds a current threshold level.

23. A method as recited in claim 13, in which the predetermined fault state is selected from a group of predetermined fault states comprising a temperature fault state and a current fault state, where:

when the temperature fault state exists, the engine control portion controls engine RPM in inverse relationship to the temperature of the engine; and

when the current fault state exists, the engine control portion controls engine RPM in inverse relationship to the output current of the generator.