Integrated generator field flash
The present invention provides an engine coupled to a generator, the generator being in communication with an automatic voltage regulator. The automatic voltage regulator has an integrated field flash circuit. Further, a controller may be in communication with the field flash circuit and the controller may control an output of the field flash circuit.
The present application claims the benefit of U.S. Provisional Patent Application No. 61/248,849 filed on Oct. 5, 2009, and the same is herein incorporated by reference in its entirety.
GOVERNMENT RIGHTSThe present invention was made with U.S. Government assistance under Department of Defense contract Number W15P7T-04-D-A003. The U.S. Government has certain rights in the invention.
BACKGROUNDThe present application is directed to unique systems, apparatus, and methods involving an electric power generator driven by an internal combustion engine.
A generator set (genset) typically includes an electric power generator together with an internal combustion engine structured to mechanically drive the generator to produce electricity. Genset implementation varies greatly, including both mobile and stationary applications, primary and standby/backup power, controlled and uncontrolled environments, and the like. In many applications it is desired that the genset operate outdoors, being able to tolerate environmental extremes of temperature, humidity, precipitation, and the like. Over time, AC generators may lose magnetism after long periods of storage and may not produce residual AC. To flash the generator, a generator operator or maintenance crew would connect an external relay to the field signals of an AC generator while rotating the machine. This process potentially results in unsafe voltages as well as insufficient flashing current. Accordingly, there remains an ongoing need for further contributions in this area of technology.
SUMMARYOne embodiment of the present application includes a unique generator set (genset) configuration. Other embodiments include unique genset systems, apparatus, and methods. Further embodiments, inventions, forms, objects, features, advantages, aspects, and benefits of the present application are otherwise set forth or become apparent from the description and drawings included herein.
The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:
For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
One nonlimiting embodiment of the present application includes genset equipment capable of providing a 30 kiloWatt (kW) VAC output. In operation, the genset is suitable for deployment in the battlefield to provide a soldier with the continuous power generation necessary for today's fielded electronic devices and various electrical equipment demands. It is developed to be fixed (skid mounted) or mobile (trailer mounted) allowing flexibility of movement. The housing assembly serves as the protective shell for the generator set. The housing has been designed with openings for maintenance and additional acoustical protection to further silence the generator set while operating. The generator has been ruggedized for unusual/harsh weather and to shield from debris.
In a further embodiment, an engine which is mechanically connected to a generator is started. A determination is made of when the engine speed reaches a starter disconnect speed. The starter disconnect speed may vary based on the specific engine and starter configuration utilized. When the engine has reached the starter disconnect speed, a flash current may be applied to the generator. A determination may be made of whether the generator is producing a residual AC voltage. If the generator is not producing a residual AC voltage, a flash current may then be applied to the generator. However, the generator may be flashed regardless of determining if the generator is producing a residual AC voltage, based on the demands of the end user. Furthermore, when the engine disconnect speed exceeds the starter disconnect speed, the AVR may enter an open-loop mode. In other embodiments, the AVR may remain in a closed loop mode throughout the flashing process; however, remaining in a closed loop mode may be less desirable based on production costs. Once the AVR has entered an open loop mode, a flash current may be applied to the generator until a target voltage output is read by the controller. After the target voltage is read by the controller, the AVR may be reverted to a closed-loop mode of operation.
In a further embodiment, when applying the flash current to the generator, over-current and over-voltage conditions are prevented through the use of PWM values (e.g. each PWM value corresponds to a voltage value as is commonly known in the art). Applying a flash current to the generator may also include sending a signal to flash the generator from the controller to a DC-DC converter, the DC-DC converter then sending a flash current to the generator.
In yet a further embodiment of the present invention, an engine is configured to provide mechanical power to a generator. The engine may be one of a gas turbine engine, a gasoline engine, a diesel engine, or any other engine capable of supplying sufficient mechanical power to drive a generator as is known by one of ordinary skill. An electrically isolated DC-DC converter is interfaced with an AVR, whereby the DC-DC converter is capable of providing a flash current to the generator upon command from a controller. Software logic may be incorporated into the controller. The software logic may contain a plurality of PWM values, each value corresponding to one of a plurality of voltage values. The software logic may also contain other commands, modes, operations, and the like. The DC-DC converter may be electrically isolated through the use of a diode, a switch, a field effect transistor, or any other device capable of providing electrical isolation known to one of ordinary skill. In an exemplary embodiment, the DC-DC converter can receive power from a genset battery as this is a convenient source of power for the DC-DC converter in the present genset configuration.
Further embodiments for automatically flashing an AC generator without operator intervention will follow. These embodiments eliminate the need for separate field flash circuitry as well as the need for an external relay because the field flash circuitry is incorporated into the AVR. In one embodiment, an integrated DC-DC converter, a diode, and software logic are configured to automatically flash an AC generator each time the engine hits starter disconnect speed on a genset startup. An isolated DC-DC converter is electrically isolated, allowing the flashing circuit to operate in cases of self-excited (e.g. shunt) gensets as well as separately excited (e.g. PMG or Quad) gensets. When the engine speed has passed a starter disconnect speed, the software logic enables the AVR into a boot mode, or open-loop mode. In the boot mode, the software logic reads the 3-phase average voltage of the generator output and automatically enables the DC-DC converter as well as driving an AVR transistor to a pre-determined level through PWM. The software logic can limit the DC-DC converter current into the generator field by controlling the open loop PWM during the boot mode. This process protects the DC-DC circuit from over-current and also prevents the output voltage from an over-voltage condition. While in open loop mode, the software logic may contain a pre-determined PWM vs. Voltage table that safely applies field flash current until a satisfactory output voltage is read by a controller. After the 3-phase average voltage of the generator reaches a pre-determined level (e.g. the field flash setpoint), the software logic can disable the DC-DC converter and the AVR reverts to a closed-loop mode of operation.
All housing body panels are connected using corrosion-resistant captive nuts. All seals for the panels are mechanically fastened to the housing panels. The top panel is shown in
Next referring to
The DCS is powered by a 24-VDC subsystem of the genset. Once genset mode, voltage, and frequency are determined by the DCS programming, the control automatically adjusts the display to show corresponding value limits, menus, and operational parameters. This embodiment of the genset provides limited remote operation capabilities through interface with an International Business Machine (IBM)-compatible PC. The operational status of the generator set can be monitored, and an emergency stop can be executed from up to a 250-foot (ft) (76.2-meter (m)) distance. The DCS includes a display that is a colored liquid crystal display (LCD) with a 6.5-inch (in) (165.1-millimeter (mm)) diagonal viewing area. It provides a combination of switches and LCD soft keys to allow the operator and maintainer to control the generator set. A high-level DCS control diagram is provided in
In one form, the genset engine is a Cummins QSB 4.5 Tier III engine. The vertical, water-cooled, four-cycle direct injection (DI) diesel engine utilizes a four-cylinder, turbocharged process that includes a cylinder head and valve cover, crankcase assembly, pistons, main bearing case, and lubrication system. This particular engine has a built-in close crankcase ventilation (CCV) system. The engine produces mechanical energy and interconnects with the AC generator via a rotating shaft. It is mounted to the skid toward the front panel of the generator set.
A cooling system for the genset includes three cooling fans (
To facilitate proper operation under extreme cold conditions, a winterization kit (
The genset fuel system is next described. It includes fuel fill (
The genset 24-VDC electrical system uses two 12-V batteries (
The AC generator (
The AC generator and voltage control system are of a drip-proof, guarded machine type and are synchronous and brushless, as specified in National Electrical Manufacturers Association (NEMA) Standard No. MG, part 33; the bearings are sealed and permanently lubricated; the AC electric power generation system leads are identified with permanent marker; and/or such leads are brought out of the frame through non-abrasive bushings and holders in the output terminal board to isolate each lead and hold it securely in place.
In certain embodiments, when operating in three-phase at rated load and frequency, the AC generator can be configured to withstand, without damage, two consecutive short circuits at the load terminals of 10 sec or less in duration within a 5-min interval at less than 300% of rated output current. The output box is located on the right-side panel and distributes electricity produced by the AC generator through the output terminal board. The output box contains the output terminal board, individual load terminals, and unit relays. All relays are socket-mounted and secured with a cover. The relay will not move unless the cover is removed.
The embodiment of
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.
Claims
1. A system, comprising:
- an engine operably coupled to a generator;
- an automatic voltage regulator operably coupled to the generator, the automatic voltage regulator having an integrated field flash circuit; and
- a controller in communication with the field flash circuit, the controller controlling an output of the field flash circuit.
2. The system of claim 1, wherein the field flash circuit is electrically isolated.
3. The system of claim 2, wherein a diode between the field flash circuit and the generator electrically isolates the field flash circuit.
4. The system of claim 1, wherein the field flash circuit further comprises a DC-DC converter operably coupled to an electrical energy source, the DC-DC converter being in communication with the controller, the controller controlling an output of the DC-DC converter.
5. The system of claim 4, wherein the DC-DC converter is electrically isolated.
6. The system of claim 1, wherein the controller is further structured to determine when the engine has reached a starter disconnect speed; and
- in response to determining when the engine has reached a starter disconnect speed, flashing the generator.
7. The system of claim 6, wherein the controller is further structured to apply field flash current until a target output voltage is achieved by the generator, the controller using a plurality of pulse-width modulation (PWM) values, each value corresponding to one of a plurality of voltage values.
8. The system of claim 1, wherein the automatic voltage regulator has an open-loop mode operable during generator flashing.
9. The system of claim 1, wherein the automatic voltage regulator has a closed-loop mode operable when a generator voltage output has reached a target output voltage.
10. An apparatus, comprising:
- an engine operably coupled to a generator;
- an automatic voltage regulator in communication with the generator and in communication with a controller; and
- means for flashing the generator.
11. The apparatus of claim 10, further comprising a means for controlling the open loop pulse-width modulation during a boot mode.
12. The apparatus of claim 10, further comprising a means for reverting the automatic voltage regulator to a closed-loop mode of operation when the voltage of the generator reaches a target voltage output.
13. A method, comprising:
- providing a generator operably connected to an engine;
- starting the engine;
- determining when the engine speed reaches a starter disconnect speed; and
- in response to determining when the engine reaches a starter disconnect speed, applying a flash current to the generator.
14. The method of claim 13, further comprising determining that the generator is not producing residual AC voltage; and
- in response to determining that the generator is not producing residual AC voltage, determining to apply a flash current to the generator.
15. The method of claim 13, further comprising determining when the engine disconnect speed exceeds the starter disconnect speed;
- in response to determining when the engine disconnect speed exceeds the starter disconnect speed, enabling an automatic voltage regulator to enter an open loop mode;
- in response to entering an open loop mode, applying a flash current to the generator until a target voltage output is read by the controller; and
- in response to obtaining a target voltage output, reverting the automatic voltage regulator to a closed loop mode.
16. The method of claim 15, wherein applying the flash current to the generator until a target voltage output is obtained further comprises preventing at least one of over-current and over-voltage through the use of a plurality of PWM values, each value corresponding to one of a plurality of voltage values.
17. The method of claim 15, wherein applying a flash current to the generator further comprises:
- sending a flash signal from the controller to a DC-DC converter; and
- in response to the DC-DC converter receiving the flash signal, sending a flash current from the DC-DC converter to the generator.
18. A method, comprising:
- providing a generator operably coupled to an engine, at least one of the generator and the engine being in communication with a controller;
- interfacing an electrically isolated DC-DC converter with an automatic voltage regulator, the DC-DC converter providing a flash current to the generator upon command from the controller.
19. The method of claim 18, further comprising integrating software logic into the controller, the software logic containing a plurality of PWM values, each value corresponding to one of a plurality of voltage values.
20. The method of claim 18, further comprising providing at least one of a diode, a switch, or a field effect transistor between the DC-DC converter and the generator, electrically isolating the DC-DC converter.
21. The method of claim 18, the DC-DC converter receiving power from a genset battery.
Type: Application
Filed: Oct 5, 2010
Publication Date: Apr 21, 2011
Inventors: Jean-Marie Loisel (Coon Rapids, MN), Alyssa Marlenee (St. Louis Park, MN), Arthur J. Punyko (St. Paul, MN), John R. Salchow (Minneapolis, MN)
Application Number: 12/924,775