Abstract:
A high efficiency lighting system maintains normal lighting conditions by lighting fixtures requiring DC electrical power. A power control device receives AC electrical power from a public utility converts AC power to DC power and delivers low voltage DC electrical power to lighting fixtures. A standby battery is provided to maintain power during power outages. Optionally, a photovoltaic DC electrical power source may be connected to the power control device, to provide alternate DC electrical power. In a further embodiment, a gas driven cogenerator unit may supply DC electrical power.

Description:
[0001]     This application is a continuation of application Ser. No. 11/007,965, filed Dec. 8, 2004, which application is a continuation of application Ser. No. 08/820,496 filed Mar. 19, 1997, now U.S. Pat. No. 6,933,627 dated Aug. 23, 2005, which application is a continuation-in-part of application Ser. No. 08/606,219 filed Mar. 7, 1996, which is a continuation-in-part of application Ser. No. 08/328,574, filed Oct. 24, 1994, now U.S. Pat. No. 5,500,561 dated Mar. 19, 1996, which was a continuation of application Ser. No. 08/129,375, filed Sep. 29, 1993, which is a continuation of application Ser. No. 07/944,796, filed Sep. 14, 1992, which is a continuation of application Ser. No. 07/638,637, filed Jan. 18, 1991. These applications are incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The field of the invention is high efficiency uninterruptible lighting systems.  
         [0003]     Uninterruptible power supplies are well known accessories especially when applied to computer equipment to “ride out” brief power outages so that no data is lost or compromised. Some have more battery storage capability so that operation may be maintained for an extended outage. Some special lighting systems are also protected in a similar fashion by an uninterruptible power source for critical applications such as operating rooms in hospitals. In lieu of such systems, reduced amounts of auxiliary emergency lighting is provided for special areas by modular systems which are only engaged during power outages; these modules are often used in stairwells and consist of a housing enclosing a battery, charger, power sensor and one or two flood lamps.  
         [0004]     These prior art systems do nothing to enhance lighting efficiency, and would not be considered as substitutes for conventional lighting.  
       OBJECTS OF THE INVENTION  
       [0005]     It is an object of this invention to provide an uninterruptible lighting system that can be routinely substituted for conventional building or office lighting.  
         [0006]     It is another object of this invention to provide high efficiency operation with lower operating cost than conventional incandescent and fluorescent lighting systems.  
         [0007]     It is yet another object of this invention to provide long term uninterruptibility (3 hours +) with small storage volumes.  
         [0008]     It is an object of this invention to provide optimum battery management for long storage life, ultra low maintenance, and economical operation.  
         [0009]     It is a further object of this invention to provide for economical connection to an alternate energy source such as a solar photovoltaic (PV) panel.  
         [0010]     It is another object of this invention to provide a system with enhanced safety through low voltage operation between the power control unit and the lighting fixtures.  
         [0011]     It is yet another object to achieve high power quality with low interference through very high power factor and low total harmonic distortion.  
         [0012]     It is an object of this invention to provide for expansion of the lighting system through a modular approach to increase subsystem and component standardization to reduce cost.  
       SUMMARY OF THE INVENTION  
       [0013]     In keeping with these objects and others which may become apparent, the present invention includes a high efficiency lighting system for maintaining normal lighting conditions by lighting fixtures requiring DC electrical power.  
         [0014]     The system includes a power control means for receiving AC electrical power from a grid source and delivering required low voltage DC electrical power to the lighting fixtures. The power control means converts the AC electrical power to DC electrical power.  
         [0015]     A battery provides, on a standby basis, the required DC low voltage electrical power to the power control means. The battery is connected to the power control means so that the battery may be maintained in a fully charged condition by the power control means during normal supply of AC electrical power from the grid source.  
         [0016]     The power control means delivers required DC electrical power from the battery to the lighting fixtures during an AC electrical power outage to maintain the power without interruption.  
         [0017]     The power control means can be a plurality of multiple power control means, each connected to its own battery for maintaining the lighting in a building with multiple rooms.  
         [0018]     An optional photovoltaic source of DC electrical power may be connected to the power control means for reducing the amount of electrical power taken from said grid source.  
         [0019]     The battery provides, on a standby basis, DC low voltage electrical power to the power control means, which power control means maintains the battery in a fully charged condition by electrical power from an AC grid source.  
         [0020]     In a version using AC power input only without an auxiliary battery or photovoltaic panel, the high efficiency lighting system for maintaining normal lighting conditions of lighting fixtures requiring DC electrical power, includes the power control means for receiving AC electrical power from a grid source and delivering required DC electrical power to the lighting fixtures, as well as a power control means converting AC electrical power to DC electrical power.  
         [0021]     In a further embodiment for remote use, such as a remote campsite without access to conventional AC power, a high efficiency lighting system maintains normal lighting conditions of lighting fixtures requiring DC electrical power. The remote system includes a power control means for receiving DC electrical power from a photovoltaic panel and delivering required low voltage DC electrical power to the remote lighting fixtures, and the power control means controls charging of a battery.  
         [0022]     The battery also provides, on a standby basis, the required DC low voltage electrical power to the power control means. It is connected to the power control means while being maintained in a charged condition by the power control means, during daylight hours of input of power from the photovoltaic panel.  
         [0023]     Moreover, the power control means delivers required DC electrical power from the battery to the lighting fixtures during periods of time when power from the photovoltaic panel is not available, such as at night times.  
         [0024]     The present invention also provides A DC power supply system for DC loads requiring DC electrical power that includes power control means for receiving AC electrical power from a grid source and delivering required low voltage DC electrical power to said DC load. It converts the AC electrical power to DC electrical power.  
         [0025]     In addition, one embodiment of the present invention includes a battery means that provides required DC low voltage electrical power on a standby basis to the power control means.  
         [0026]     The battery means is connected to the power control means so as to permit the battery control means to maintain the battery in a fully charged condition during normal supply of AC electrical power from the AC grid source.  
         [0027]     The power control means of the present invention delivers required DC electrical power from the battery means to a DC load during an AC electrical power outage so as to maintain normal operation of the DC load without interruption.  
         [0028]     In addition, the present invention optionally provides a DC power supply system having a photovoltaic [PV] source of DC electrical power connected to the power control means in order to reduce the amount of electrical power taken from said grid source.  
         [0029]     The DC power supply system of the present invention optionally further provides a cogeneration source of DC electrical power connected to the power control means to reduce the amount of electrical power taken from a grid source.  
         [0030]     Further, the present invention alternatively provides a DC power supply for DC loads requiring DC electrical power. The DC power supply includes a separate power control means for receiving AC electrical power from a grid source. The DC power supply delivers required low voltage DC electrical power to a DC load. The power control means converts the AC electrical power to DC electrical power.  
         [0031]     In addition, in an alternate embodiment, the DC power supply system for DC loads requiring DC electrical power includes a power control means for receiving DC electrical power from a DC power source and for delivering required low voltage DC electrical power to the DC load. The power control means is also directed toward the function of controlling charging of a battery means.  
         [0032]     In this battery-charging embodiment, the present invention&#39;s battery means provides the required DC low voltage electrical power on a standby basis to the power control means.  
         [0033]     Also, in this battery-charging embodiment, the battery means is connected to the power control means so as to maintain the power control means in a charged condition during hours of input from the DC power source.  
         [0034]     Furthermore, in this battery-charging embodiment, the power control means delivers required DC electrical power from the battery means to the DC load during times when power from the DC power supply is not available.  
         [0035]     The DC power supply system of the present invention further provides an optional embodiment wherein the DC power source is a cogeneration unit.  
         [0036]     Alternatively, in a different embodiment of the present invention, the DC power supply system has a DC power source that is at least one photovoltaic panel.  
         [0037]     In yet another embodiment of the present invention, the DC power supply system furnishes power to a DC load that is a household appliance. The household appliance may alternatively be a microwave oven, a heater, or any other household electrical device.  
         [0038]     Furthermore, in further embodiments with or without access to conventional AC power, a DC generator (e.g. powered by a natural gas engine) is used either as a primary source of electrical power or as a cogeneration companion to normal AC grid power. Thus the power control means can be supplied power for use by a high efficiency lighting system in much the same manner as DC electrical power is received from a photovoltaic panel.  
         [0039]     It can be appreciated that any compatible DC load can be serviced by the power control means of this high efficiency lighting system in addition to DC ballasted fluorescent lighting or instead of the latter lighting load. These other DC loads can be supplied with standby power from a storage battery as well. Some examples of DC loads include household appliances, microwave ovens, and heaters. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0040]     The present invention can best be understood in conjunction with the accompanying drawings, in which:  
         [0041]      FIG. 1  is a block diagram of basic uninterruptible lighting system;  
         [0042]      FIG. 2  is a physical block diagram of basic uninterruptible lighting system;  
         [0043]      FIG. 3  is a wiring layout of a single lighting module;  
         [0044]      FIG. 4  is a wiring layout of a four module system;  
         [0045]      FIG. 5  is a block diagram of lighting system with a PV panel;  
         [0046]      FIG. 6  is a front view of power control unit;  
         [0047]      FIG. 7  is a wiring diagram and specs for two lamp ballast;  
         [0048]      FIG. 8  is a wiring diagram and specs for single lamp ballast;  
         [0049]      FIG. 9  is a front view of battery enclosure; and  
         [0050]      FIG. 10  is a block diagram of power control unit.  
         [0051]      FIG. 11  is a block diagram of an alternate lighting system using natural gas cogeneration.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0052]      FIG. 1  shows a block diagram of the major components of an uninterruptible lighting system of this invention. It may be installed anywhere conventional building lighting is required. Unlike emergency lighting, this is a full service, high quality lighting product. It functions with standard fixtures and lamps, without compromise in output quality and with no flicker in the event of a power failure. This permits normal building activities to continue for several hours using battery storage without disruption of work activity due to loss of lighting. The key subsystem that ties the entire system together is the power control unit  1  which normally uses AC grid power to supply the lighting energy and keep the battery  2  charged. The lighting fixtures  3  are fluorescent tubes using electronic ballasts which have a low voltage (nominal 26.6 volts) DC input supplied by line  5  from power control unit (PCU)  1 . During a power outage, the DC line  5  is supplied by battery  2 .  
         [0053]      FIG. 2  shows a physical block diagram showing the AC electric service panel  6  with a three wire cable system supplying either 120 or 220 VAC to PCU  1 . Battery case  7  contains two group 24/27 deep discharge lead acid storage batteries wired in series and through a 30 amp fuse to the PCU  1 . The wiring to all lighting fixtures  3  is at a nominal 26.6 volts DC. In the preferred embodiment, each PCU can power ten two tube 48 inch T 8  fluorescent fixtures or 20 single tube fixtures.  
         [0054]      FIG. 3  shows a wiring layout for three offices as controlled by a single PCU  1 . A closet area  17  is used to house battery  2 . The AC line  4  leads to PCU I which is placed in the ceiling cavity. The DC wiring  5  to the lighting fixtures is also in the ceiling cavity.  
         [0055]     The 220 VAC input power to the PCU is 725 watts for an AC rms of approximately 3 amps. The equivalent 120 VAC unit will be about 6 amps. Because the PCU is power factor corrected to 0.99, a 20 amp circuit breaker and number  12  wire can support a maximum of 3 PCU&#39;s from a 120 volt line and 6 units from a 220 volt line for a total DC power output of about 2100 watts and 4200 watts respectively.  
         [0056]      FIG. 4  shows a wiring layout serving  8  small offices and four larger ones. This involves the use of four separate uninterruptible lighting systems using four PCU&#39;s  1  and four battery modules  2  located in four central closets  17 . The four PCU&#39;s are supplied from a single 220 VAC circuit breaker in power panel  6  via AC cable  4  as distributed from distribution box  20 . Each of the lighting systems supplies  10  two lamp fixtures  3 .  
         [0057]      FIG. 5  shows an uninterruptible lighting system including a PV panel  25 .  
         [0058]     As shown in  FIG. 6 , a front view of PCU  1 , it is simply wired to two terminals. This simple system configuration permits high security lighting using an AC line, battery back-up, and PV shared contribution. A system with the PCU alone attached to the AC line is a viable lighting system that can pay for itself by providing high efficiency DC lighting. By adding the battery subsystem, the user achieves uninterruptible lighting. By using a system without a battery but with AC input and a PV panel, the power savings of the PV contribution is achieved with the balance supplied by the AC input. In an area remote from the AC grid, a system using a PCU attached to a large PV panel and a larger battery can supply totally solar lighting. The PCU is sufficiently flexible to support all of these configurations of lighting systems. It can also supply other DC loads besides lighting, such as for example, household appliances, microwave ovens, heaters and the like. Furthermore, it can also alternately accept external DC power from many varied sources such as wind generators or engine powered generators.  
         [0059]      FIG. 6  shows a front view of PCU  1  with finned heat sink  28  and terminal strip  29 .  
         [0060]      FIGS. 7 and 8  show the wiring diagrams and specifications for the two lamp and one lamp DC ballasts respectively (designated as NB2756/2 and NB2727M respectively).  
         [0061]      FIG. 9  shows a front view of the battery case with hinged lid  36  and latches  37 . It is a thermoplastic case rated only for sealed type lead acid batteries.  
         [0062]      FIG. 10  shows a block diagram of the PCU  1 . The AC input is rectified by DC Rectifier Means  150  such as a bridge circuit. The Power Factor Correction Means  151  is used to achieve a high power factor (0.99) at the AC input. The Control Means  153  and Voltage Regulator means  152  interact through circuits such as pulse width modulation and DC to DC switching power supply topologies to provide the nominal 26.6 volts to the lighting ballasts or other suitable DC loads  157  through the power junction means  155 . Other voltages are also possible, such as 13.3, 26.6, 39.9 etc.  
         [0063]     The Battery Undervoltage Cut-Off  156  disconnects the battery  2  in situations of depletion to prevent “over sulfation” or chemical and physical damage to the storage battery. The PV Voltage Regulator and Suppressor  154  is a power conditioner block to suppress voltage transients (such as from lightning strikes in the vicinity) and also to prevent over charging of the storage battery from the PV panel  25 .  
         [0064]     An embodiment of control means  153  determines if the utility power drawn is above a manually pre-set threshold or a threshold derived from an automatic setpoint circuit. If the utility power drawn exceeds this threshold, voltage regulator means  152  output voltage will be set such that power junction means  155  will be biased accordingly such that power to DC loads  157  will be drawn from storage battery  2  and/or PV source  25  through its PV voltage and suppressor  154 . In this manner, AC power peaks from the utility are reduced as are monthly utility charges if a peak power surcharge is assigned. The power sharing between PV source  25  and battery  2  is regulated by the output voltage of PV source  25  as modified by PV voltage regulator and suppressor  154 . The interaction of voltage output at suppressor  154  with that of battery  2  voltage via biasing within power junction means  155  determines the level of power sharing between these DC secondary sources. The latter action also describes the sharing of power between PV panel  25  and battery  2  during periods of utility power outage.  
         [0065]      FIG. 11  is an alternate embodiment for a loadside powered lighting system including natural gas in a cogeneration component. AC power  50  is normally converted to DC power by DC power converter  51  and control means  52 . However, a cogenerator in the form of a DC gas generator  53  receives natural gas from a natural gas source  54 , and sends DC power to building lighting system  55 , such as electronic ballasted fluorescent lighting. This system provides a flatter and more predictable power demand for electric utility customers at building lighting system  55 , since it supplants peak power from electric utility generating sources. This results in reduced demand charges, since gas offers a lower cost per unit of energy consumed, compared to conventional AC power from a public utility.  
         [0066]     The cogeneration system can run continuously for lighting load  55 , without having to be sent back to AC line power  50 , which avoids the need for costly AC synchronization methods and sine wave purity, as is needed when sending excess electricity back to a public utility.  
         [0067]     DC gas generator  53  directly couples to building lighting system  55  through a diode isolator that allows either AC or DC power to operate building lighting system  55 .  
         [0068]     Other modifications may be made to the present invention without departing from the scope of the invention, as noted in the appended claims.