Abstract:
An intelligent power distribution system distributes power on a vehicle. The system includes at least a first power source and a second power source for supplying electrical power, and at least a first power block and a second power block, each connected to receive power from the first power source and the second power source. Each power block includes at least one load and a power selector having a first input for receiving power from the first power source and a second power source and an output for supplying power from either the first power source or the second power source to the at least one load. The power selector selects either the first power source or the second power source for provision to the at least one load based on characteristics of the at least one load.

Description:
BACKGROUND 
     The present invention is related to power distribution systems, and in particular to intelligent power distribution systems. 
     Electrical power distribution systems employed in vehicles such as aircraft provide for the redundant distribution of power from a plurality of power sources to a plurality of loads. Each load is associated with one of a plurality of power distribution buses, which in turn is connected to one of the plurality of power sources. The system is redundant in that if one of the power sources fails, another one of the plurality of power sources can be used to supply the power distribution bus with power. In this power distribution topology, all loads connected to a particular power bus are supplied with power from a single power source. 
     However, a drawback of this topology is some loads create transients on the power distribution bus that can adversely affect the loads connected to the same power distribution bus. Typically, large (and therefore expensive) filters are required to reduce the effects of those transients. 
     SUMMARY 
     An intelligent power distribution system for distribution power on an aircraft, includes at least a first power source and a second power source for supplying electrical power, and at least a first power block and a second power block, each connected to receive power from the first power source and the second power source. Each power block includes at least one load and a power selector having a first input for receiving power from the first power source and a second power source and an output for supplying power from either the first power source or the second power source to the at least one load. The power selector selects either the first power source or the second power source for provision to the at least one load based on characteristics of the at least one load. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a circuit diagram of a power distribution system as known in the prior art. 
         FIG. 2  is a circuit diagram of a power distribution system according to an embodiment of the present invention. 
         FIG. 3  is a circuit diagram of a power block according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The power distribution system of the present invention provides for the intelligent distribution of power to various loads onboard a vehicle. A benefit of this approach is it allows for the intelligent isolation of “noisy” loads from “clean” loads. 
       FIG. 1  is a circuit diagram of power distribution system  10  as known in the prior art. Power distribution system  10  includes power sources  12   a - 12   c , contactors  14   a - 14   e , loads  16   a - 16   f , and power distribution buses  18   a - 18   c . Power supplied by power sources  12   a - 12   c  is distributed via selective control of contactors  14   a - 14   e  to power distribution buses  18   a - 18   c  for supply to loads  16   a - 16   f . In this type of power distribution architecture, loads  16   a - 16   f  draw power from whichever power source  12 - 12   c  is presently supplying power to the power distribution bus  18   a - 18   c  with which the load is associated. For example, loads  16   a  and  16   b  are associated with power bus  18   a , and will therefore draw power from whichever power source  12   a - 12   c  is configured to supply power to power distribution bus  18   a.    
     The benefit of this long-utilized power distribution topology is it provides power supply redundancy to each of the plurality of loads. For example, power source  12   a  supplies power to power distribution bus  18   a  through selective control of contactors  14   a  and  14   b  (i.e., by closing contactor  14   a  and opening contactor  14   b ). In the event power source  12   a  fails, power source  12   b  may be employed to supply power to power distribution bus  18   a  by selectively closing contactor  14   b  (and typically opening contactor  14   a ). 
     However, this power distribution topology requires that load  16   a  and  16   b  (as well as load pairs  16   c ,  16   d  and load pairs  16   e ,  16   f ) be sourced with power from the same power source. In the event that one of the loads (e.g., load  16   a ) is a “noisy” load that creates a lot of distortion on power distribution bus  18   a , those distortions are communicated to the loads sharing the same power distribution bus. 
       FIG. 2  is a circuit diagram of power distribution system  20  according to an embodiment of the present invention. Power distribution system  20  includes a plurality power sources  22   a - 22   c , power blocks  24   a - 24   f  and power distribution buses  26   a - 26   c . Each of the plurality of power blocks  24   a - 24   f  is connected to receive power from each of the plurality of power distribution buses  26   a - 26   c , and therefore each power block  24   a - 24   c  is capable of receiving power from any one of the plurality of power sources  22   a ,  22   c . For purposes of this description, loads associated with power blocks  24   a ,  24   c , and  24   e  are classified as “noisy” (i.e., loads with varying energy consumption in terms of varying current, electromagnetic interference, and/or power factor), while loads associated with power blocks  24   b ,  24   d , and  24   f  are described as “clean” (i.e., loads with consistent energy consumption in terms of current flow, electromagnetic interference and/or power factor). 
     Each power block  24   a - 24   f  is therefore capable of drawing power from any one of the plurality of power sources  22   a - 22   c . For example, power block  24   a  is connected to each of the plurality of power sources  22   a - 22   c , and may selectively draw power from one of the plurality of power sources. This is in contrast with the power distribution system described with respect to  FIG. 1 , in which each load  16   a - 16   f  was restricted to drawing power from the power bus to which it was connected, and as a result from whichever power source was providing power to the power bus associated with the load. A benefit of power distribution system  20  is “noisy” loads associated with power blocks  24   a ,  24   c , and  24   e  can be configured to draw power from one of the plurality of power sources (e.g., power source  22   a ) while “clean” loads associated with power blocks  24   b ,  24   d , and  24   f  can be configured to draw power from a different power source (e.g., power source  22   c ). In this way, “noisy” loads  24   a ,  24   c , and  24   e  do not adversely affect “clean” loads  24   b ,  24   d , and  24   f.    
     In one embodiment, each of the plurality of power blocks  24   a - 24   f  is pre-programmed with information regarding the type of load (e.g., “noisy” or “clean”) to which it is connected, and based on this a priori information determines the appropriate power source  22   a - 22   c  from which it should draw power. In another embodiment, rather than program power blocks  24   a - 24   f  with information about the type of load to which it is connected, each power block is programmed with information about the power source  22   a - 22   c  from which it should draw power. In both of these embodiments, prior knowledge of the system architecture (i.e., the loads which will be connected to each power block) is required to program power blocks  24   a - 24   f.    
     In addition, each power block  24   a - 24   f  may further include information regarding what power sources to connect to in the event the current power source fails or becomes unavailable. For example, power blocks  24   a ,  24   c  and  24   e  associated with “noisy” loads may be programmed to selectively draw power from power source  22   b  in the event power source  22   a  becomes unavailable. 
     In the embodiment shown in  FIG. 2 , each power block  24   a - 24   f  is connected to communication bus  28  for communicating with other power blocks  24   a - 24   f  and/or with controller  30 . Communication between controller  30  and the plurality of power blocks  24   a - 24   f  may include information regarding the type of load (e.g., “noisy”, “clean”, etc.) associated with each power block and the power source  22   a - 22   c  from which the power block is currently drawing power. This information is used by controller  30  to make determinations regarding from which power supply  22   a - 22   c  each power block  24   a - 24   f  should draw power. Communication between power blocks  24   a - 24   f  and controller  30  may be used in conjunction with a priori programming such that controller  30  of each power block  24   a - 24   f  to coordinate power source selections in the event one or more power sources becomes unavailable, or may be used in place of a priori programming such that controller  30  dynamically determines the power source  22   a - 22   c  from which each power block  24   a - 24   f  will draw power. A benefit of this approach is it allows power distribution system  20  to dynamically respond to changing load conditions. For example, the load associated with power block  24   a  may initially be classified as a “clean” load and be assigned to draw power from power source  22   c . During operation, the load associated with power block  24   a  may become “noisy”. Power block  24   a  monitors the power drawn and communicates the change in load characteristics to controller  30 . In response, controller  30  may instruct power block  24   a  to connect to a different power source (e.g., power sources  22   a - 22   c ) reserved for “noisy” loads. 
     Classification of a load (e.g., classifying a load as either “noisy” or “clean”) may be done locally by each of the power blocks  24   a - 24   f  based on monitored characteristics of the load, or may be done centrally by controller  30  based on information communicated from each of plurality of power blocks  24   a - 24   f . Classification of loads associated with each of the power blocks may be based on monitoring of voltage, current, power and/or combinations thereof. 
     In one embodiment, control of each of the plurality of power blocks  24   a - 24   f  is centralized in controller  30 , which receives inputs from each of the plurality of power blocks  24   a - 24   f  and in response provides instructions/commands to each of the plurality of power blocks  24   a - 24   f  regarding the power source  22   a - 22   c  from which the power block should draw power. In another embodiment, control of each of the plurality of power blocks  24   a - 24   f  is distributed among the plurality of power blocks, with no centralized controller. In this embodiment, power blocks  24   a - 24   f  communicate via communication bus  28  with one another, and determine in a distributed manner the power sources  22   a - 22   c  from which each of the plurality of power blocks  24   a - 24   f  should draw power. 
       FIG. 3  is a circuit diagram of power block  24   a  according to an embodiment of the present invention. In the embodiment shown in  FIG. 3 , power block  24   a  includes power selector  32  and load  34 . Power selector  32 , in turn, includes switch matrix  36 , local controller  38  and sensor  40 . 
     Power from each of the plurality of available power sources  22   a - 22   c  is provided as an input to power selector  32 . Within power selector  32 , switch matrix  36  includes a plurality of inputs for receiving power from each of the plurality of available power sources  22   a - 22   c , an output for providing one of the plurality of power sources  22   a - 22   c  to load  34 , and a plurality of switches S 1 -S 3  selectively controlled by local controller  38  to determine the power source  22   a - 22   c  provided to load  34 . Various switches and switch configurations may be employed to apply one of the plurality of power sources  22   a - 22   c  as an output to load  34 . For example, switches may make use of electro-mechanical switches, such as relays, or solid-state switch devices such as metal-oxide semiconductor field-effect transistors (MOSFETs), insulated gate bipolar transistors (IGBTs), and silicon carbide (SiC) switches. Likewise, various switch configurations may be employed to multiplex power from the input of switch matrix  36  to the output of switch matrix  36 . 
     In one embodiment, local controller  38  is programmed with a priori information regarding the type of load  34  to which it is connected (e.g., “noisy”, “clean”) and/or the power source  22   a - 22   c  to be used to supply power to load  34 . In this embodiment, while local controller  38  may communicate with other power blocks  24   b - 24   f , the selection of power to be supplied to load  34  is predetermined based on knowledge of the load and the power source  22   a - 22   c  selected to source particular types of loads. 
     In other embodiments, local controller  38  communicates with controller  30  (and/or other power blocks  24   a - 24   f ) to dynamically determine the appropriate power source to provide to load  34 . Communication provided by local controller  38  may include characteristics of the load as monitored by sensor  40 , determinations made by local controller  38  regarding whether the load is “noisy” or “clean,” and the power source  22   a - 22   c  presently connected to supply power to load  34 . In response, local controller  38  receives commands/instructions from controller  30  (and/or power blocks  24   b - 24   f ) selecting a power source  22   a - 22   c  to supply to load  34 . 
     In the embodiment shown in  FIG. 3 , sensor  40  is a current sensor configured to monitor current supplied to load  34 . Detected transients in the monitored current are indicative of a “noisy” load and can be used to classify a load as either “noisy” or “clean”. The monitored current characteristics can be communicated to controller  30  or may be processed locally by local controller  38  to classify the load (e.g., as either “noisy” or “clean”). If processed locally, then the classification of the load is communicated by local controller  38  to controller  30 . In other embodiments, other types of sensors may be employed to monitor other characteristics (e.g., voltage, power) of the power being supplied to load  34 . Local controller  38  receives the monitored characteristics, and based on the monitored characteristics determines whether the load is “noisy” or “clean”. 
     While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.