Abstract:
A power distribution system that provides supervision and protection. Hall effect devices are used to monitor power from a central power supply to a plurality of power converters. Fuses are connected between the converters and the central power source to protect the converters from catastrophic failure. Hall effect devices also monitor the output of power from the converters. A current controlling inductor is included between the converter outputs and the output power bus in order to restrict reverse current flow from a time that is sufficient to allow a circuit breaker to disconnect a failed converter. The Hall effect devices are connected to a computer which monitors the power in and out of the converters. The computer is thus able to detect a failed converter and disconnects it by operating an associated circuit breaker.

Description:
FIELD OF THE INVENTION 
     The present invention relates to power distribution systems and more particularly to a power distribution system for use in an electronic system. 
     BACKGROUND OF THE INVENTION 
     Power distribution systems are old and well-known. Typically they include a plurality of converters that are connected to the central power supply. Associated with each converter is a circuit breaker which is operated when the associated converter fails. A signal indicating such failure is often sent to a computer which then provides a signal or printout to inform an attendant of the converter failure. 
     Such systems, however, are limited to disconnection of failed converters. They do not provide for constant monitoring of the efficiency of the converters in order to detect a malfunctioning converter before it fails. Also, prior art systems do not protect malfunctioning converters from catastrophic failure since such systems do not restrict reverse current from other converters for the time required to disconnect a malfunctioning converter. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a power distribution system is provided for use in an electronic system that includes a load bus, a load connected to the load bus, and a direct current power source which is operative to provide power of a first characteristic. The power distribution system includes an input power monitoring circuit that is connected to the power source and a plurality of power conversion circuits that are connected to the input powe montoring circuit. 
     The input power monitoring circuits are operative to monitor current flow from the power source to the power conversion circuits, and to provide a plurality of power input status signals, each associated with a different one of the power conversion circuits. Each of the power conversion circuits are operative to convert the power supplied by the power source to power of a different characteristic. 
     The power distribution system also includes an output power monitor and control circuit that is connected between the plurality of power conversion circuits and the load bus, and this circuit is operative both to monitor current flow from the power conversion circuits and to provide a plurality of power output status signals, each associated with a different one of the power conversion circuits. 
     A power comparison circuit is also included and it is connected to the input power monitoring circuit and the output power monitor and control circuit. This comparison circuit is operative to compare the power input and output status signals to predetermined values therefor, and to provide a failure signal for each status signal that does not correspond to its predetermined values. 
    
    
     DESCRIPTION OF THE DRAWING 
     The single FIGURE of the accompanying drawing is a combined schematic and block diagram of the power distribution system of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the accompanying drawing the power distribution system of the present invention is shown connected to a -48 volt power source, a +5 volt bus and a computer. Conductor 100 is connected to the -48 volt power source and the assembly of Hall effect device 110 and flux concentrator 110A is located in magnetic field proximity thereto. Hall effect device 110 is also connected to the computer. A plurality of power conversion and monitoring circuits are connected to conductor 100. Three such circuits 200, 300 and 400 are shown connected. However, the present invention is not limited to only three power conversion and monitoring circuits. The present invention will be described with reference to power conversion and monitoring circuit 200 since the other power conversion and monitoring circuits are identical. 
     Power conversion and monitoring circuit 200 includes fuse 210 which is connected between conductor 100 and conductor 220. The asembly of Hall effect device 221 and flux concentrator 221A is located in magnetic field proximity to conductor 220 and Hall effect device 221 is electrically connected to the computer. Conductor 220 is further connected to contact 230 which is magnetically coupled to solenoid 231. Converter 240 is connected to contact 230, conductor 250, and controller 241 which is also connected to solenoid 231. The assembly of Hall effect device 251 and flux concentrator 251A is located in magnetic field proximity to conductor 250 and Hall effect device 251 is also electrically connected to the computer. Contact 260 is connected to conductor 250 and it is magnetically coupled to solenoid 261 which is connected to the computer. Inductor 270 is connected between contact 260 and conductor 500 which is further connected to the +5 volt bus. The assembly of Hall effect device 510 and flux concentrator 510A is located in magnetic field proximity to conductor 500 and this Hall effect device 510 is also electrically connected to the computer. 
     When converter 240 is operating properly current flows from the -48 volt power source, through conductor 100, fuse 210, conductor 220, contact 230 and into converter 240. This converter then provides a +5 volt output potential and causes a resultant current to flow through conductor 250, contact 260, inductor 270, conductor 500 and the +5 volt bus, if a load is connected to that bus. Conductor 100 generates a magnetic flux in response to current flow through it. Hall effect device 110 indirectly monitors this current flow since it monitors the magnetic flux generated by inductor 110 and concentrated by concentrator 110A. Hall effect device 110 then provides a signal to the computer representative of the current flowing out of the -48 volt power source. 
     Fuse 210 is effective to prevent catastrophic failure to converter 240 since it opens the path of current flow through this converter when the current reaches an excessive leel for a predetermined period of time. 
     Conductor 220 generates a magnetic flux in response to current flowing through it and converter 240. Hall effect device 221 monitors the magnetic flux generated by conductor 220 and therefore it indirectly monitors the current flowing into converter 240. Hall effect device 221 then provides a signal to the computer representing the current flowing through converter 24. Thus, the computer is able to monitor, via Hall effect device 110, the total current flowing into the power distribution system and it is also above to monitor, via Hall effect device 221, the current flowing into converter 240. 
     Converter 240 operates to convert the -48 volt potential occuring at its input to one or more different voltages at its output. Typically, these converters provide a +5 volt, +12 volt, or both potentials at their output. In the present application converters 240, 340 and 440 provide a +5 volt potential which is applied to the +5 volt bus. Controller 241 monitors the operation of converter 240 and upon detection of a malfunction in this converter, it operates solenoid 231. When this solenoid operates, it opens contact 230, thereby disconnecting converter 240 from the -48 volt power source. When converter 240 is operating properly, the +5 volt potential, appearing at the output of converter 240, is applied to the +5 volt bus via conductors 250 and 500, inductor 270 and contact 260. 
     If a load is attached to the bus then a resultant current flows through conductor 250 which then generates a magnetic flux. Hall effect device 251 monitors this magnetic flux and provides a signal representative thereof to the computer. Thus, the computer is provided with an indication of the current flowing into the converter, via Hall effect device 221, and the current flowing out of the converter, via Hall effect device 251. The computer is therefore able to determine the efficiency of the converter by comparing these input and output signals to each other and to predetermined values therefor. Since a predetermined efficiency is expected for converter 240, any variation therefrom can be determined by the computer. In the event that the efficiency is below a minimum acceptable level, the computer operates solenoid 261 which causes contact 260 to open, thereby disconnecting converter 240 from the +5 volt bus. 
     Inductor 270 is a current controlling inductor. In the event that converter 240 should fail, inductor 270 restricts the current flow from other converters into this failed converter. Such inflow of current is restricted to the magnetizing level of current for inductor 270. When converter 204 fails, current through inductor 270 must first decrease to zero and then reverse direction and flow into converter 240. The time required for this reverse current flow to build up to the magnetizing level of inductor 270, is greater than the time required for computer 270 to detect the failure in converter 240 and operate solenoid 261. Therefore, converter 240 is protected from damage due to excessive reverse current since it is disconnected from the +5 volt bus, via contact 260, before reverse current can exceed the magnetizing level of inductor 270. Converter 240 thus is also prevented from pulling down the voltage on the +5 volt bus. 
     Conductor 500 is connected to the junction of inductors 270, 370 and 470 and it thus creates a magnetic flux in response to current flowing from converters 240, 340 and 440. Hall effect device 510 monitors the magnetic flux generated by conductor 500 and provides a signal to the computer with represents the total current generated by converters 240, 340 and 440. Therefore, the computer is provided with an indication of the total current flowing out of converters 240, 340 and 440. By comparing this output current with the current input as indicated by the signal from Hall effect device 110, the computer is able to determine the overall efficiency of converters 240, 340 and 440. The resultant efficiency can be compared with a predetermined expected efficiency and computer printouts or other signalling means can be used to provide an indication of the actual versus the expected efficiency of these converters. 
     Thus, each converter has its input and output power measured on a continuous basis, by Hall effect devices. The output of the Hall effect devices is a voltage that is proportional to the monitored power. The signals provided by the Hall effect devices are applied to the computer. The computer could include a comparator for each Hall effect device. This comparator would be set to the voltage equivalent of the maximum power that is permitted in a given circuit. If that power is exceeded, the comparator provides a corresponding signal and the computer takes corrective action, such as operating fast acting solenoid 260. 
     The signals from the Hall effect devices could also be applied directly to a computer controlled supervisory system. This computer system would frequently check the Hall effect device signals to verify that the converters share the load properly. Deviations from predetermined expected ratios would again result in corrective action being taken, such as operating fast acting solenoid 260 or providing a computer printout for maintenance personnel. 
     The present invention also provides for fail safe operation since, if a single Hall effect device does not operate properly, this condition will be detected by the computer by means of cross checks with corresponding Hall effect devices. 
     Thus, the power distribution system of the present invention provides a novel, highly reliable and fail safe means of distributing power from a power source to a load bus. Hall effect devices are used to monitor current flowing from the power source, into and out of the various power converters, and into the load bus. Each of the Hall effect devices provides a signal representative of its respective detected current flow. These signals are applied to a computer which monitors these signals and compares them to predetermined expected values. Fuses are used to prevent catastrophic failure due to prolonged high current conditions. Logic controlled relays are used to disconnect a failed converter from the power source, and fast acting computer controlled relays are used by the computer to disconnect a malfunctioning converter from the load bus. Current controlling inductors are used to delay current build up in the converters for the time period required for the fast acting relays to operate and thereby disconnecting the converters from the load bus. 
     It will be obvious to those skilled in the art that numerous modifications of the present invention can be made without departing from the spirit of the invention which shall be limited only by the scope of the claims appended hereto.