Abstract:
A power distribution system in which a power source is configured to supply an amount of high-frequency input power to a centralized frequency converter unit. The centralized frequency converter unit is configured to convert the high-frequency input power into low-frequency converted power. Passenger Electronic Device Controllers receive the converted power and distribute it to outlet units. Power management functions may be integrated with the distribution system. For instance, the centralized frequency converter unit can cause to be disabled unused outlet units when the power drawn by the used outlet units exceeds a predetermined threshold.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The subject matter of the present disclosure generally relates to power distribution systems, and more particularly relates to centralized conversion of high-frequency alternating current into low-frequency alternating current. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    The distribution of power among several loads presents certain challenges. This can be particularly true in environments where there is a limited amount of available power, but where hardware complexity and duplication are disadvantageous. 
         [0003]    For instance, in commercial aircraft, power having certain characteristics should be supplied simultaneously to numerous consumer power outlets for use in powering personal electronic devices, such as laptops or cellular telephones. Previous aircraft power distribution systems typically involve the distribution of raw aircraft power from a head-end device such as a power management system or circuit breaker, through a side wall disconnect panel to a first seat group. Power is then distributed from the first seat group to additional seat groups through seat-to-seat cabling that carries the power required by seat mounted power conversion units, which in turn provide power to a passenger interface at household voltage and frequency. Power carried through such seat-to-seat distribution networks is often 115 volt alternating current (VAC), three-phase power of either fixed (400 Hz) or variable (360-800 Hz) frequency. Seat power converters are necessary to convert this power to 110 VAC 60 Hz or other voltages to power passengers&#39; electronic devices. 
         [0004]    Systems of this type require seat power converters that are suitable for use with an aircraft platform, and thus they preferably have certain capabilities and characteristics, such as power factor correction, a low electromagnetic interference (EMI) signature, low current harmonics and a low load demand variation. Thus, the seat power converters often contain complex circuitry, such as energy storage and filtering devices, to adequately meet these requirements. In addition to the disadvantages inherent in complex circuitry, undesirable heat is generated at the point of conversion by processing power locally at the passengers&#39; seats. 
         [0005]    Often, various power management functions are accomplished alongside power distribution. Certain load distribution and management systems (LDMSs) have been previously disclosed. U.S. Pat. No. 5,754,445, titled “Load Distribution and Management System,” by Jouper et al. relates to such systems. U.S. Pat. No. 6,046,513, titled “Load Distribution and Management System,” by Jouper et al., U.S. Pat. No. 8,295,065, titled “System control by use of phase rotation signaling” by Jouper, and U.S. Pat. App. No. 2012/0,139,341, titled “System control by use of phase rotation signaling,” by Jouper, each relate to LDMSs. The disclosures of U.S. Pat. Nos. 5,754,445, 6,046,513, 8,295,065 and U.S. Pat. App. No. 2012/0,139,341 are hereby incorporated by reference herein in their entirety. 
         [0006]    The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above. 
       BRIEF SUMMARY OF THE DISCLOSURE 
       [0007]    Disclosed is a system for the distribution of power to several loads. In an embodiment, a power source supplies high-frequency input power to a Frequency Converter Unit (FCU) that is configured to convert the high-frequency input power into low-frequency converted power. The converted power is distributed to various outlet units through Passenger Electronic Device Controllers (PEDCNTs), each of which is associated with several outlets. 
         [0008]    An objective of the disclosed subject matter is to centralize the power conversion process and efficiently distribute the native power required by the passenger electronic devices, without requiring conversion circuitry to be associated directly with seating units. 
         [0009]    The subject matter of the present disclosure offers several advantages. For instance in passenger vehicles, distributing 60 Hz power to passenger seating has the advantage of eliminating the need to locally process the power at the seating in order to provide power to end-user devices. Control of power flow to the outlet unit, as well as safety functionality such as ground fault interruption and circuit breaker functionality, can all be accomplished with little power loss at the seat interface. Each seat device does not have to meet all of the power requirements of the aircraft as it is not directly attached to the aircraft power bus. Furthermore, in certain aircraft-based embodiments, the distribution of low-frequency power rather than high-frequency power may not require different power infrastructure in respect to wire sizes and run lengths, particularly because 110 VAC power is very similar in many respects to 115 VAC power. 
         [0010]    One advantage of the presently disclosed subject matter is that the size and weight of seat power units and their accompanying hardware are reduced. Weight reduction may be particularly advantageous to aircraft operators, as even small weight savings can lead to increases in aircraft performance, reduced initial capital and maintenance costs, and significant cost savings over the operational life span of the aircraft, particularly from reduced fuel consumption. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing summary, preferred embodiments, and other aspects of the present disclosure will be best understood with reference to a detailed description of specific embodiments, which follows, when read in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a schematic diagram of an embodiment contained within a commercial aircraft. 
           [0013]      FIG. 2  is a schematic diagram of a centralized frequency converter unit of an embodiment. 
           [0014]      FIG. 3  is a schematic diagram of a passenger electronic device controller of an embodiment. 
       
    
    
       [0015]    Like reference numbers and designations in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0016]      FIG. 1  is a schematic illustration of an embodiment. Aircraft power distribution and management system  101  has power source  102  that provides high-frequency input power to FCU  103 . In the embodiment, power source  102  is a generator driven by an aircraft engine. FCU  103  converts the high-frequency input power into low-frequency converted power. PEDCNTs  104  receive power from FCU  103  and cause it to be distributed to outlet units  105 . In the embodiment, outlet units  105  are consumer power outlets located at the passenger seats of the aircraft. PEDCNTs can optionally distribute power to power outlet units through outlet assemblies, which may, for instance, include power switching means for turning an outlet unit “on” or “off.” 
         [0017]    In the embodiment depicted in  FIG. 1 , two independent zones are controlled, each with an FCU operating in conjunction with one or more PEDCNTs. In the embodiment, PEDCNTs  104  are depicted as being connected in series to FCU  103 , though parallel connection may also be implemented. It should be understood by those of skill in the art to which the present disclosure pertains that the described FCUs and PEDCNTs may be employed in any suitable number or configuration. 
         [0018]    High-frequency power as used in the present disclosure refers to current having a frequency inclusive of between 360 and 800 Hz. Low-frequency power as used in the application refers to current having a frequency inclusive of between 50 and 60 Hz. 
         [0019]    Specifically, the high-frequency input power may be 115 VAC 400 Hz three-phase power, 115 VAC 360-380 Hz three-phase power, 230 VAC 400 Hz three-phase power or 230 VAC 360-380 Hz three-phase power, and the low-frequency converted power can be 110 VAC 60 Hz three-phase power. 
         [0020]    Some embodiments may perform power management functions in addition to distribution functions. For instance, in a situation where additional power is not available, the FCU may be configured to disable unused outlet units so that additional loads are not added to the power system, while still allowing those outlet units that are already drawing power to continue doing so. Thus, disruption to the passengers of a vehicle employing such an embodiment would be reduced, while load management is still accomplished effectively. 
         [0021]    Some PEDCNTs of certain embodiments may, in addition to a status whether power is available, make use of additional inputs in determining whether to disable unused outlet units. Power management may thus be accomplished in response to the dynamic circumstances in which an embodiment may operate. For instance, a PEDCNT may disable unused outlets in a decompression situation on an aircraft, thereby conserving power for more critical aircraft systems. 
         [0022]      FIG. 2  is a schematic diagram of FCU  201  of an embodiment. High-frequency input power is received along input power lines  202  and is fed to EMI filter  203 , where electromagnetic filtering is conducted. Switching noise from internal circuits is suppressed and filtered to prevent it from entering back into input power lines  202 . FCU central processing unit (CPU)  204  monitors the input power to determine whether it is within the nominal voltage and frequency range (typically 102-122 VAC and 360-380 Hz). When the input voltage is within an allowable range, relays  205  are closed to allow power to flow to three-phase power factor correction (PFC) unit  206 . PFC unit  206  corrects for current harmonics and power factor to satisfy aircraft platform requirements. In the embodiment, PFC unit  206  has PFC subunits  207 , each of which contributes current at 350 volts potential to the high voltage rail Hi Rail Direct Current Unit  208 . This intermediate voltage is used to store energy for short periods of power loss, typically in the range of 1-200 mSec. The intermediate voltage is fed to current inversion unit  209 , which consists of 60 Hz AC inverters  210  and inversion CPU  211 . Inversion CPU  211  provides a 60 Hz pulse width modulation signal causing inversion unit  209  to output 110 VAC three-phase power. Output control unit  212  has output relays  213  and output CPU  214 . Output CPU  214  monitors and controls power flow through output control unit  212 . Specifically, output CPU  214  monitors the power used on each phase of the three-phase 60 Hz output power. One phase of power is output over each of power lines  215 ,  216  and  217 . Interface &amp; host processor  218  is configured to provide to output CPU  214  an ON or OFF signal. Auxiliary power supply  219  and auxiliary hold up  220  provide working voltages for the internal circuitry of FCU  201 . It will be understood by those of skill in the art to which the present disclosure pertains that various electronic components and circuit designs are suitable for employment within FCU units. 
         [0023]    Interface &amp; host processor  218  interprets signals from the other vehicle systems. In an aircraft, information regarding decompression, weight-on-wheels, power availability, and system On/Off status allow FCU  201  to control the system as necessary during various flight phases. 
         [0024]    In the embodiment, output CPU  214  monitors the output of FCU  201  and when the power consumed is equal to a preprogrammed system maximum, signals to inversion CPU  211  to the change the phase rotation, for example from phase A, B, C over power lines  215 ,  216  and  217 , to phase A, C, B over power lines  215 ,  216  and  217 . Thus, three-phase power is still output from FCU  201 , however, the phase rotation change signals to a PEDCNT downstream that additional power is unavailable and to restrict the use of then unused outlet assemblies. 
         [0025]      FIG. 3  is a schematic illustration of a portion of an embodiment including PEDCNT  301 , that operates to control outlet assemblies  302 ,  303 , and  304 . Three-phase 60 Hz power is fed from a FCU into three-phase EMI filter  305 , which removes or suppresses undesirable electromagnetic noise. The resultant power is fed to three-phase ground fault interruption (GFI) unit  306  and to phase rotation detection unit  307 . Microcontroller  308  receives a Power AVAIL signal from phase rotation detection  307  when power is available. 
         [0026]    The output of three-phase GFI unit  308  is fed to outlet assemblies  302 ,  303 , and  304 . The number of outlets attached to the PEDCNT  301  are a design choice and can be a single unit or any plurality. Each outlet unit is fed by two solid state switches, one for each of two phases feeding the outlet. This implementation assumes a three-phase delta power configuration at the input of PEDCNT  301 . Other implementations will be apparent to those of skill in the art to which the present application pertains, including without limitation the use of electromechanical switches and power gating methods. In the embodiment, the voltage differential between phases A and B is 110 VAC with a single phase voltage of 63.6 VAC for each of the three phases. The difference voltage is equal to 1.73 multiplied by the voltage-per-phase. A control signal is used to turn “on” or “off” solid state switches  309  and  310  in order to control outlet unit  311 . An outlet unit sense line detects when a power cord is plugged into outlet  311  and a power request signal is fed to microcontroller  308 . 
         [0027]    Microcontroller  308  evaluates the power request signal and analyzes it in conjunction with the Power AVAIL signal to determine whether power should be supplied to outlet unit  311 . Phase rotation detection unit  307  determines if the three-phase power is of a normal rotation (for example, phases A, B, and C along lines 1, 2 and 3, respectively) or if the rotation has reversed (for example, phases A, C, and B along lines 1, 2 and 3, respectively). A normal rotation signifies that additional power is available. A reverse rotation signifies that the system is in a restricted power mode and that new requests for power from outlet units should be denied. If power is available, microcontroller  308  will cause solid state switches  309  and  310  to enter an ON status in response to the power request signal. If power is unavailable, as signaled by a reverse phase rotation in the embodiment, than microcontroller  308  will not permit power to be supplied to then unused outlet units, but will continue to allow power flow to outlets that are already in use when additional power became unavailable. 
         [0028]    In a preferred embodiment, a central conversion unit (or FCU) is used to convert 115 VAC three-phase power of high-frequency (fixed or variable) to 60 Hz 110 VAC three-phase power for distribution throughout seat interface units to a number of outlet units located in the cabin of a commercial aircraft. 
         [0029]    The central conversion unit may supply power to all of the passenger outlet units in the aircraft, or, optionally, the cabin can be split into several zones, each served by a separate central conversion unit. The central converter provides for power factor correction, harmonic control, and Electromagnetic Interference (EMI) filtering, as needed by the particular aircraft. These functions may be accomplished with a three-phase boost converter, power factor corrector and an appropriate EMI Filter. The output DC voltage of the power factor corrector stage would then be processed by an inverter to create a 60 Hz AC sine wave output in a three-phase configuration. This AC sine wave output could be of either a “Y” configuration with a NEUTRAL return and a line voltage of 110 VAC or a delta (“A”) configuration where the line-to-line voltage is 110 VAC and no neutral connection is required. The advantage of the “A” configuration is the elimination of the need for an additional connection between the central converter and all of the downstream seat units, which reduces the overall system weight by eliminating the need for a wire and associated wiring harness. The wires, including the neutral wire, maybe of the same wire gage so that each wire can carry the total capacity of any one phase of power. The wire gage for an AC line in such an embodiment may optionally be 16 AWG. The weight savings from eliminating the need for an additional wire can be significant. In a typical wide-bodied aircraft, ˜800 feet of wire may be eliminated, accounting for approximate 8 pounds of 16 AWG wire. Over the life cycle of the aircraft, significant cost savings from such a reduction can be achieved. 
         [0030]    Although the disclosed subject matter has been described and illustrated with respect to embodiments thereof, it should be understood by those skilled in the art that features of the disclosed embodiments can be combined, rearranged, etc., to produce additional embodiments within the scope of the invention, and that various other changes, omissions, and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.