Electrical power generation system and method
First Claim
1. A system for generating electrical power for supply to a load, comprising:
- an air-breathing engine mechanically communicating with a movable shaft, the engine being structured and arranged to receive a mixture of air and fuel and burn the mixture such that the mixture expands and creates mechanical power that is used to drive the shaft;
a fuel system coupled with the engine and operable to supply fuel to the engine, the fuel system being responsive to a fuel control signal to vary a rate of fuel flow to the engine;
at least one engine sensor operable to measure at least one thermodynamic variable associated with the engine that is indicative of a relative thermodynamic efficiency of the engine;
an electrical generator coupled to the shaft such that movement of the shaft by the engine causes the generator to operate to create an alternating electrical current, the engine, shaft, and generator being connected such that a change in speed of the generator causes a corresponding change in speed of the engine and hence a change in rate of air flow through the engine;
a power electronics unit coupled to the generator for receiving the alternating electrical current therefrom and operable to synthesize an alternating output current and voltage at a predetermined frequency and relative phase for supply to the load;
a generator power sensor operable to measure power output from generator;
a load power sensor operable to measure power demanded by the load; and
a controller operably connected to the fuel system, to the at least one engine sensor, to the power electronics unit, to the generator power sensor, and to the load power sensor, the controller being operable to control the fuel system so as to cause the power output from the system to substantially match the power demanded by the load, and simultaneously to electrically control the generator to regulate speed thereof so as to control air flow rate through the engine in such a manner that fuel/air ratio of the mixture burned in the engine is controlled to substantially maximize the relative thermodynamic efficiency of the engine.
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Accused Products
Abstract
An electrical power generating system and method wherein a generator is driven by an air-breathing engine. At any operating condition, for a given power output the engine efficiency is substantially optimized by controlling the rate of air flow through the engine in such a manner that the fuel/air ratio is controlled to maintain a high peak temperature imparted to the working fluid in the engine. The method and system of the invention eliminate the need for variable-geometry mechanisms in the engine, and also eliminate the need for variable-geometry combustors and pre-burners. The invention is applicable to various types of air-breathing engines that operate at low fuel/air ratios.
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Citations
29 Claims
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1. A system for generating electrical power for supply to a load, comprising:
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an air-breathing engine mechanically communicating with a movable shaft, the engine being structured and arranged to receive a mixture of air and fuel and burn the mixture such that the mixture expands and creates mechanical power that is used to drive the shaft;
a fuel system coupled with the engine and operable to supply fuel to the engine, the fuel system being responsive to a fuel control signal to vary a rate of fuel flow to the engine;
at least one engine sensor operable to measure at least one thermodynamic variable associated with the engine that is indicative of a relative thermodynamic efficiency of the engine;
an electrical generator coupled to the shaft such that movement of the shaft by the engine causes the generator to operate to create an alternating electrical current, the engine, shaft, and generator being connected such that a change in speed of the generator causes a corresponding change in speed of the engine and hence a change in rate of air flow through the engine;
a power electronics unit coupled to the generator for receiving the alternating electrical current therefrom and operable to synthesize an alternating output current and voltage at a predetermined frequency and relative phase for supply to the load;
a generator power sensor operable to measure power output from generator;
a load power sensor operable to measure power demanded by the load; and
a controller operably connected to the fuel system, to the at least one engine sensor, to the power electronics unit, to the generator power sensor, and to the load power sensor, the controller being operable to control the fuel system so as to cause the power output from the system to substantially match the power demanded by the load, and simultaneously to electrically control the generator to regulate speed thereof so as to control air flow rate through the engine in such a manner that fuel/air ratio of the mixture burned in the engine is controlled to substantially maximize the relative thermodynamic efficiency of the engine. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for controlling an electrical generator system having an air-breathing engine mechanically communicating with a movable shaft, the engine being structured and arranged to receive a mixture of air and fuel and bum the mixture such that the mixture expands and creates mechanical power that is used to drive the shaft, the system having a fuel system coupled with the engine and operable to supply fuel to the engine, the fuel system being responsive to a fuel control signal to vary a rate of fuel flow to the engine, the system having an electrical generator coupled to the shaft such that movement of the shaft by the engine causes the generator to operate to create an alternating electrical current, wherein the engine, shaft, and generator are connected such that a change in speed of the generator causes a corresponding change in speed of the engine and hence a change in rate of air flow through the engine, and the system having a power electronics unit coupled to the generator for receiving the alternating electrical current therefrom and operable to synthesize an alternating output current and voltage at a predetermined frequency and relative phase for supply to the load, wherein electrical power output from the system is substantially determined by fuel flow rate to the engine, the method comprising the steps of:
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determining a power demanded by the load;
measuring at least one thermodynamic variable associated with the engine that is indicative of a relative thermodynamic efficiency of the engine;
controlling the fuel supply system to supply fuel to the engine at a controlled fuel flow rate such that the electrical power output from the system substantially matches the power demanded by the load; and
controlling the air flow rate through the engine independently of the electrical power output from the system so as to control fuel/air ratio of the mixture burned in the engine in such a manner as to substantially optimize the thermodynamic efficiency of the engine while substantially matching the power demanded by the load, the air flow rate being controlled by electrically controlling the speed of the generator and hence the air flow rate through the engine. - View Dependent Claims (18)
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19. A method for controlling an electrical generator system having an air-breathing engine mechanically communicating with a movable shaft, the engine being structured and arranged to receive a mixture of air and fuel and burn the mixture such that the mixture expands and creates mechanical power that is used to drive the shaft, the system having a fuel system coupled with the engine and operable to supply fuel to the engine, the fuel system being responsive to a fuel control signal to vary a rate of fuel flow to the engine, the system having an electrical generator coupled to the shaft such that movement of the shaft by the engine causes the generator to operate to create an alternating electrical current, wherein the engine, shaft, and generator are connected such that a change in speed of the generator causes a corresponding change in speed of the engine and hence a change in rate of air flow through the engine, and wherein electrical power output from the system is substantially determined by fuel flow rate to the engine, the method comprising the steps of:
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determining a power demanded by the load;
measuring at least one thermodynamic variable associated with the engine that is indicative of a relative thermodynamic efficiency of the engine;
controlling the fuel supply system to supply fuel to the engine at a controlled fuel flow rate such that the electrical power output from the system substantially matches the power demanded by the load;
operating upon the alternating electrical current from the generator so as to produce a non-alternating direct current at a non-alternating voltage;
operating upon the non-alternating direct current so as to synthesize an alternating output current and voltage at a predetermined frequency and relative phase for supply to the load;
controlling the air flow rate through the engine independently of the electrical power output from the system so as to control fuel/air ratio of the mixture burned in the engine in such a manner as to substantially optimize the thermodynamic efficiency of the engine while substantially matching the power demanded by the load, the air flow rate being controlled by actively controlling the non-alternating direct current so as to alter the speed of the generator and hence the air flow rate through the engine. - View Dependent Claims (20, 21, 22)
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23. A method for improving part-load efficiency of an air-breathing engine in an electrical generator system, the system having a movable shaft mechanically communicating with the engine and a fuel system coupled with the engine and operable to supply fuel to the engine at a controlled fuel flow rate, the engine being designed such that peak thermodynamic efficiency of the engine substantially coincides with a design point operating condition of the engine, the system having an electrical generator coupled to the shaft such that movement of the shaft by the engine causes the generator to operate to create an alternating electrical current, wherein the engine, shaft, and generator are connected such that a change in speed of the generator causes a corresponding change in speed of the engine and hence a change in rate of air flow through the engine, and wherein electrical power output from the system is substantially determined by fuel flow rate to the engine, the method comprising the steps of:
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operating the engine at a first part-load condition; and
at said first part-load condition, controlling the speed of the generator so as to control air flow rate through the engine while simultaneously controlling fuel flow rate to the engine so as to control fuel/air ratio in such a manner that a peak cycle temperature of the engine is substantially the same as the peak cycle temperature corresponding to the design point operating condition. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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Specification