Engine driven power inverter system with cogeneration

• US 7,239,034 B2
• Filed: 03/11/2005
• Issued: 07/03/2007
• Est. Priority Date: 03/16/2004
• Status: Active Grant

• Current Assignee: Tecogen Inc.
• Original Assignee: Tecogen Inc.
• Inventors: Gehret, Joseph B. Jr.
• Primary Examiner(s): Schuberg; Darren
• Assistant Examiner(s): Cuevas; Pedro J.
• Application Number:
  US11/078,191
• Publication Number:
  US 20050206167A1
• Time in Patent Office: 844 Days
• Field of Search: 290/2, 290/40.B, 322/24
• US Class Current: 290/40.00B
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 53/57 Charging stations without connection to power networks
• CPC Class Codes: B60L 8/003 Converting light into electric energy, e.g. by using photo-voltaic systems
• CPC Class Codes: F02C 6/18 using the waste heat of gas-turbine plants outside the plants themselves, e.g. gas-turbine power heat plants using waste heat as source of energy for refrigeration plants F25B27/02; using the waste heat of a gasturbine for steam generation or in a steam cycle see F01K23/10
• CPC Class Codes: F02D 2250/24 by using an external load, e.g. a generator
• CPC Class Codes: F02D 29/06 peculiar to engines driving electric generators
• CPC Class Codes: F02D 41/0205 using an auxiliary engine speed control engine speed control per se F02D31/00
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations

Abstract

A combined heat and AC power generating system is disclosed having black start capability for the full time, simultaneous production of both electricity and heat. Heat generated within the system is captured and used for heating applications such as heating building air and tap water. The power generating system comprises an engine, generator, rectifier, variable frequency drive inverter, and inverter control electronics. The system provides improved efficiency and prolonged engine life by always operating the engine with its throttle fully open to obtain maximum efficiency and the engine is normally operated near its stall point. In this operating state the inverter control electronics adjust the power output from the inverter to control the speed of the engine. This is done by increasing the power output from the inverter when the power drawn by the load decreases. This causes the engine to operate closer to its stall point and it slows down. The power from the inverter is decreased when the power drawn by the load increases. This causes the engine to operate further from its stall point and it speeds up. The slight power changes to facilitate this operation will always be drawn from or distributed to the electric utility grid so there is no wasted power. The inverter control electronics are responsive to signals from loads such as refrigeration loads to cause the frequency of the inverter output to change to permit the refrigeration load to operate more efficiently.

Claims

1. A combined heat and AC power generating system, the combined heat and AC power generating system comprising:

an internal combustion engine mechanically coupled to a rotating shaft;

an exhaust system for removing combustion gases from said enginel;

a permanent magnet alternator having a rotor mechanically coupled to the shaft and generating AC power;

rectifying means for converting the AC power from said alternator to DC power;

inverter means for converting the DC power from said rectifying means to AC power having a defined amplitude and a frequency different than the AC power output from said alternator;

a water jacket around said internal combustion engine;

a water jacket around said exhaust system;

a heat exchanger;

means for passing water through said water jacket around said internal combustion engine and said water jacket around said exhaust system to remove heat from said internal combustion engine and said exhaust system, the removed heat being utilized for purposes including heating building air and heating tap water;

a first sensor for sensing the speed of said engine and providing a first signal;

a second sensor for sensing the amount of power being output from said inverter means and providing a second signal; and

an electronic control unit responsive to the first and second signals for generating a control signal to said inverter for controlling the amount of power being output from said inverter means and thereby controlling the speed of said internal combustion engine.

2. The combined heat and AC power generating system of claim 1 further comprising a water jacket around said alternator and said means for passing water forces water through said alternator water jacket.

3. The combined heat and AC power generating system of claim 2 further comprising a water tank for holding water after it has passed through said heat exchanger.

4. The combined heat and AC power generating system of claim 3 wherein said means for passing water comprises a water pump for pumping water from said water tank to the water jackets of the engine, alternator and exhaust system.

5. The combined heat and AC power generating system of claim 1

wherein said engine is always run at its highest efficiency, normally near its stall point, with its throttle fully open, and (a) as the power consumed by the load decreases, this is sensed by said second sensor and the control signal generated by said electronic control unit causes said inverter to output more power which is not wasted but which increases the load on said engine and thereby slows said engine down to operate at a more efficient speed to provide the decreased amount of power consumed by the load, or (b) as the power consumed by the load increases, this is sensed by said second sensor and the control signal generated by said electronic control unit causes said inverter to output less power which is not wasted but which decreases the load on said engine and thereby speeds said engine up to operate in a more efficient speed to provide the increased power consumed by the load.

6. The control apparatus of claim 4 wherein the load uses AC power from both a utility power grid and from said inverter and when said inverter is caused to output more power to slow said engine down, the excess power output from said inverter means is returned to the utility power grid and is not wasted.

7. The combined heat and AC power generating system of claim 1 wherein said inverter means is a variable frequency drive inverter means for converting the DC power from said rectifying means to output AC power for a load, the output power from the variable frequency drive inverter means has an amplitude and different frequencies as required by the load when the load requires different amounts of power at different frequencies to make the load operate more efficiently, and further comprising:

a first sensor for sensing the speed of said engine and providing a first signal;

a second sensor for sensing the operating point of said inverter means and providing a second signal; and

an electronic control unit responsive to the first and second signals for generating a control signal to said inverter means for controlling the amplitude and frequency of the power being output from said inverter means to the load.

8. The combined heat and AC power generating system of claim 6 wherein said inverter means is a variable frequency drive inverter means for converting the DC power from said rectifying means to output AC power for a load, and the output power from said variable inverter means has an amplitude and different frequencies as required by the load to operate more efficiently.

9. Control apparatus for an AC power generating system that has an internal combustion engine, an alternator connected to and driven by the engine to generate AC power, rectifying means for converting AC power from the alternator to DC power, a controllable inverter means for converting the DC power from the rectifying means to output AC power to a load having a defined amplitude and a frequency different than the AC power from the alternator, the control apparatus comprising:

a first sensor for sensing the speed of the engine and providing a first signal;

a second sensor for sensing the amount of power being output from the inverter means and providing a second signal;

an electronic control unit responsive to the first and second signals for generating a control signal to the inverter means for controlling the amount of power being output from the inverter means and thereby controlling the speed of the engine;

wherein the engine is always run at its highest efficiency, normally near its stall point, with its throttle fully open, and (a) as the power consumed by the load decreases this is sensed by said second sensor and the control signal generated by the electronic control unit causes the inverter to output more power which is not wasted but which increases the load on the engine and thereby slows the engine down to operate at a more efficient speed to provide the decreased amount of power consumed by the load, or (b) as the power consumed by the load increases, this is sensed by said second sensor and the control signal generated by the electronic control unit causes the inverter to output less power which is not wasted but which decreases the load on the engine and thereby speeds the engine up to operate in a more efficient speed to provide the increased power consumed by the load.

10. The control apparatus of claim 9 wherein the alternator is a permanent magnet alternator having amorphous metal stators and the AC power output from the alternator is at a frequency that is different than the frequency of the AC power output from the alternator to the load.

11. The control apparatus of claim 10 wherein the closer the engine is driven to its stall point the slower the engine will run, and the further the engine is driven from its stall point the faster the engine will run.

12. The control apparatus of claim 11 wherein the load uses AC power from both the utility power grid and from the inverter and when the inverter means is caused to output more power to slow the engine down the excess power output from the inverter means is returned to the utility power grid and is not wasted.

13. The control apparatus of claim 9 wherein the controller is used with a combined heat and AC power generating system, the engine has an exhaust system, and the heat generated by the engine, its exhaust system and the alternator is captured and is utilized for many purposes including heating building air and heating tap water.

14. The control apparatus of claim 13 wherein the inverter means is a variable frequency drive inverter used to output power having an amplitude and different frequencies as required by the load when the load requires different amounts of power at different frequencies to make the load operate more efficiently.

15. The control apparatus of claim 9 wherein the inverter means is a variable frequency drive inverter used to output power having an amplitude and different frequencies as required by the load when the load requires different amounts of power at different frequencies to make the load operate more efficiently.

16. An AC power generating system for providing AC power at different amplitudes and different frequencies to a load, the generating system comprising:

an internal combustion engine;

an alternator connected to and driven by said engine for providing AC power;

rectifying means for converting AC power from said alternator to DC power;

a variable frequency drive inverter means for converting the DC power from said rectifying means to output AC power for a load, the output power from said inverter means having an amplitude and different frequencies as required by the load to operate more efficiently;

a first sensor for sensing the speed of said engine and providing a first signal;

a second sensor for sensing the operating point of said inverter means and providing a second signal; and

an electronic control unit responsive to the first and second signals for generating a control signal to said inverter means for controlling the amplitude and frequency of the power being output from said inverter means to the load wherein said engine is always run at its highest efficiency, normally near its stall point, with its throttle fully open, and (a) as the power consumed by the load decreases this is sensed by said second sensor and the control signal generated by said electronic control unit causes said inverter means to output more power which is not wasted but which increases the load on said engine and thereby slows said engine down to operate at a more efficient speed to provide the decreased amount of power consumed by the load, or (b) as the power consumed by the load increases this is sensed by said second sensor and the control signal generated by said electronic control unit causes said inverter means to output less power which is not wasted but which decreases the load on said engine and thereby speeds said engine up to operate in a more efficient speed to provide the increased power consumed by the load.

17. The AC power generating system for providing AC power at different amplitudes and different frequencies to a load in accordance with claim 16, wherein the AC power generating system is a combined heat and AC power generating system, said internal combustion engine has an exhaust system, and the heat generated by said engine, its exhaust system and the alternator is captured and is utilized for many purposes including heating building air and heating tap water.

18. The AC power generating system for providing AC power at different amplitudes and different frequencies to a load in accordance with claim 17, wherein the load uses AC power from both the utility power grid and from said inverter means, and when the inverter means is caused to output more power to slow said engine down, the excess power output from said inverter means is returned to the utility power grid and is not wasted.

19. The AC power generating system for providing AC power at different amplitudes and different frequencies to a load in accordance with claim 16, wherein the heat generated by said engine, its exhaust system and said alternator is captured by heating water flowing over portions of said engine, its exhaust system and said alternator.