Abstract:
An electronic circuit that accepts a variable DC voltage power source and converts it to a constant DC power source, the energy of which is either stored in a battery bank or sent out to DC loads or AC loads via a DC/AC conversion subsystem. The device capable of using solar, wind, geothermal, or hydroelectric energy sources.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to and incorporates by reference U.S. Provisional Patent Application No. 61/640,134 filed on Apr. 30, 2012. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is in the technical field of energy. More particularly, the present invention is in the technical field of an electronics package suitable for portable power systems. 
     Background of the Invention 
     There has been a long standing need for portable energy devices, and in particular devices that utilize renewable energy sources. Such devices can utilize solar, wind, geothermal, or hydroelectric sources of energy. Devices can be used to power devices such as cell phones, computers, lights, as well as many other important devices. 
     Such devices are commonly used in industrialized societies to provide access when away from the electrical grid; however, given the stable and pervasive nature of the grid portable energy devices often viewed as a as a convenience rather than a necessity. 
     The is not the case in the less industrialized settings, such as in the third world, or in remote areas where the electrical grid is not as omnipresent. These devices provide critical access, and in some cases life saving access to power. 
     While prior art devices do exist they suffer from a number of drawbacks that limit the practical utility of such devices. Whereas, for example, some prior art devices convert solar energy to DC voltages such as the devices depicted in U.S. Pat. No. 6,844,739, U.S. Pat. No. 4,794,272 for Maximum Power Point Trackers, or disclosed in U.S. Pat. No. 4,969,078 or U.S. Pat. No. 7,379,284 for DC/DC converters, these devices are single in scope—they operate off a DC input and produce a DC output. Therefore, theses devices are suitable for charging a battery, which stores electricity for later use. Batteries are not particularly efficient at capturing available energy, and can take a long time to charge before they are capable of delivering enough energy to usefully power an electrical device. 
     A need exists for a portable energy device that can provide AC power to surrogate devices, as well as providing associated energy storage. 
     SUMMARY OF THE INVENTION 
     The present invention is a single, enclosed, electronic system that provides power (either AC or DC) from external energy sources (solar, wind, hydrothermal, etc.). The system has storage capability as well as providing power from either stored energy or directly from external sources. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic drawing of the present invention. 
         FIG. 2  is a circuit drawing of a voltage conversion subsystem of the present invention. 
         FIG. 3  is an alternative circuit drawing of a voltage conversion subsystem of the present invention. 
         FIG. 4  is an alternative circuit drawing of a voltage conversion subsystem of the present invention. 
         FIG. 5  is a circuit drawing of a DC-AC conversion subsystem of the present invention. 
         FIG. 6  is a perspective view of the entire device. 
         FIG. 7  is a view of the top of the device when closed. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The power system described herein is an all-in-one unit that incorporates solar panels into a portable case having electronic circuitry enclosed which are capable of storing energy generated from solar panels (or other external sources) as well as sourcing energy in the form of an AC or DC voltage. The electronic circuitry is capable of regulating the variable power source inherent in solar panels to a constant DC voltage suitable for charging a battery, and/or running a DC to AC converter. The DC-to-AC converter is capable of transforming the DC voltage to an AC voltage (110 or 220 VAC, 50 or 60 Hz) to directly power surrogate devices connected to the power device. 
     Referring now to the invention in more detail, in  FIG. 1  there is shown a diagram, outlining the operation of the electronic system. The electronic system is composed of a DC conversion subsystem ( 12  in  FIG. 1 ), a power voltage bus ( 14  in  FIG. 1 ) battery storage  16 , a DC outlet  18 , and inverter  20 . 
     More specifically, the electronic system shown in  FIG. 1  provides a method of voltage conversion ( 12  in  FIG. 1 ) to take power from external sources (such as wind, solar, hydro, etc.—or plugging directly into the electric power grid) and convert it to the bus voltage ( 14  in  FIG. 1 , nominally 24 to 36 VDC). The bus voltage  14  is specifically set by the maximum charge voltage of the storage component  16 . The power delivered to the bus is either stored in the batteries  16 , shunted to the DC outlet  18 , or shunted to the inverter  20 . The inverter  20  provides conversion from DC to AC (either 110, 220 VAC at 50 or 60 Hz) and wires from the DC outlet to the front panel or wires from the AC outlet to the front panel allow for external connection of user loads (lights, television, computers, etc.). 
       FIG. 2  shows a typical boost converter used for DC/DC conversion. It increases an external DC voltage  10  to a larger voltage heretofore referred to as the bus voltage  14 . This converter uses a magnetic component  24  to store energy during a period of time when the semiconductor switching device  30  is in a conductive state, then discharges that energy through the load leveling capacitor  28  during the period of time when the semiconductor switching device  30  is non-conductive. By varying the ratio of conductive to non-conductive time, the DC voltage controller  26  varies the ratio of input  10  to output  14  voltage. The desired bus voltage  14  is set to the maximum charge voltage of the energy storage device  16 . 
       FIG. 3  shows a variation of the boost converter known as a SEPIC converter used for DC/DC conversion. It increases an external DC voltage  10  to a larger voltage heretofore referred to as the bus voltage  14 . This converter uses a magnetic component  32  to store energy during a period of time when the semiconductor switching device  34  is in a conductive state, then discharge that energy through the boost capacitor  36  during the period of time when the semiconductor switching device  34  is non-conductive. The secondary inductor  38  acts as a current sink to insure the average current to the load capacitor  40  and the DC bus  14  remains constant. By varying the ratio of conductive to non-conductive time, the DC voltage controller  42  varies the ratio of input  10  to output  14  voltage. 
     The desired bus voltage  14  is set to the maximum charge voltage of the energy storage device  16 . 
       FIG. 4  shows a DC converter implementation using the ‘flying capacitor’ type used for DC/DC conversion. During the time period when the semiconductor switching devices  50  and  54  are conductive,  52  and  56  are non conductive, the input capacitor  44  and boost capacitor  46  are in parallel and charging, while the load leveling capacitor  48  is discharged to the voltage bus  14  at desired level. When the semiconductor switching devices  50 ,  52 ,  54 , and  56  change states, the input capacitor  44  and the boost capacitor  46  are in series, and charging the load leveling capacitor  48  to the bus voltage  14 . By varying the ratio of conductive to non-conductive time, the bus voltage can be tuned to the voltage set by the maximum charge of the batteries. 
     Moving on to the DC/AC conversion system ( 20  in  FIG. 1 ), which converts the bus voltage  14  to an alternating voltage source  22  suitable for plug in devices depending on country.  FIG. 5  shows the most typical style of DC/AC converter, known as the H-bridge. Semiconductor switching devices  60 ,  62 ,  64 ,  66  operate in opposition to each other. When  60  and  66  conduct,  62  and  64  do not, the switching devices change state, reversing the polarity of the transformer  68 . This results in an alternating positive/negative voltage at the AC output  22 . By varying the turns ratio of transformer  68 , the magnitude of the AC voltage can be tuned to coincide with the RMS voltage of a utility (120 VAC, 210 VAC, etc.). The AC Voltage Control  58  determines the frequency of oscillation, to likewise coincide with the utility (50 or 60 Hz). 
       FIG. 6  shows the entire device. Solar panels  80  and  82  are connected to the base and cover. The device flips closed for portability. The AC and DC outlets are shown in the front of the unit  84 . The solar panels generate power in the sun, which the electronics previously described either store electricity or use it for external power via the outlets  84 . The electronics are stored in the base underneath solar panels  80 . 
       FIG. 7  shows a top view of the unit closed. The top cover folds over the base via hinges  86 , and the handle  88  allows the unit to be carried. 
     The advantages of the present invention include, without limitation, a single unit that converts a variable input DC voltage to a DC voltage suitable for storing power in a battery or delivering power as an AC or DC voltage. Also, it allows portable power generation without need for external fuels such as propane, diesel, or petroleum. 
     While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention.