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Dedicated avionics standby power supply

  • US 5,864,221 A
  • Filed: 07/29/1997
  • Issued: 01/26/1999
  • Est. Priority Date: 07/29/1997
  • Status: Expired due to Fees
First Claim
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1. For use in combination with an aircraft electrical supply and distribution system that includes a DC generator having at least a first DC output to normally provide a voltage V1, a first DC distribution system for said first DC output, a main rechargeable battery connected to said first DC distribution system, a second DC output to normally provide a voltage V2, a second DC distribution system for said second DC output, and a power failure signaling system for monitoring said second DC output and supplying a power failure indication at an output thereof when said second DC output commences to fall in level from said voltage V2, whereby a power failure indication is provided for an interval before said second DC output drops fully to zero in voltage level, a standby power supply for aircraft electronic apparatus, said aircraft electronic apparatus being normally supplied with DC electrical power at said voltage V2 over said second DC distribution system, said standby power supply having a principal input for connection to said first DC distribution system, said principal input comprising a first polarity input and second polarity input, and an output for connection to said aircraft electronic apparatus for supplying DC electrical power to said aircraft electronic apparatus when the DC voltage on said second DC electrical distribution system drops below voltage V2 in the course of failure of said DC generator, comprising:

  • rechargeable battery means for storing electrical energy, said battery means having a first polarity output and a second polarity output, and said battery means having an output of voltage V3 between said first polarity output and said second polarity output, where said voltage V3 is less than said voltages V1 or V2;

    a fast pulse mode battery charger;

    said fast pulse mode battery charger having a charger input for receiving DC current, said charger input comprising a first polarity charger input and a second polarity charger input, and a charger output, said charger output connected to said rechargeable battery means for supplying DC charging current to said battery means responsive to DC current at said charger input;

    DC to DC converter means;

    said DC to DC converter means having first and second polarity inputs and an output for up-converting a DC voltage applied across said first and second polarity inputs to a second DC voltage at said output, said second DC voltage being of greater magnitude than said first DC voltage and said output of said DC to DC converter means providing said standby power supply output;

    said DC to DC converter means output providing DC electrical power at said voltage V2 to said aircraft electronic apparatus, responsive to the application of said battery output voltage V3 across said DC to DC converter inputs;

    first electromagnetic relay means;

    said first electromagnetic relay means including an electromagnetic coil means and first and second make relay contacts, said make relay contacts being normally open condition to open an electrical circuit there through when said electromagnetic coil means is unenergized and, responsive to energization of said electromagnetic coil means, for closing an electrical circuit there through;

    said first make relay contacts being connected in series with said first polarity charger input of said fast pulse mode battery charger and said first polarity input of said principal input, and said second make relay contacts being connected in series with said second polarity charger input of said fast pulse mode battery charger and said second polarity input of said principal input, wherein said fast pulse mode battery charger input is electrically isolated from said principal input when said electromagnetic coil means of said first electromagnetic relay means is unenergized, and wherein an electrical current conducting circuit between said principal input and said fast pulse mode battery charger input is completed only when said electromagnetic coil means of said first electromagnetic relay means is energized;

    said electromagnetic coil means of said first electromagnetic relay means being connected to said second DC distribution system for receiving DC energization current, responsive to said DC generator supplying said voltage V2 to said second distribution system, whereby said first relay means completes a current path to said input of said fast pulse mode battery charger when said DC generator is functioning, and interrupts said current path when said DC generator is not functioning;

    second electromagnetic relay means;

    said second electromagnetic relay means including electromagnetic coil means and first and second break relay contacts, said break relay contacts thereof being normally closed to complete an electrical circuit therethrough when said electromagnetic coil means thereof is unenergized and, responsive to energization of said electromagnetic coil means thereof, for opening said electrical circuit therethrough;

    said first break relay contacts being connected in series between said first polarity output of said rechargeable battery means and said first polarity input of said DC to DC converter means; and

    said second break relay contacts being connected in series between said second polarity input of said DC to DC converter means and said second polarity output of said rechargeable battery means;

    wherein said rechargeable battery means output is connected to said DC to DC converter means to supply current to said DC to DC converter means only when said electromagnetic coil means of said second electromagnetic relay means is de-energized and wherein said rechargeable battery means output is disconnected from said DC to DC converter means when said electromagnetic coil means of said second electromagnetic relay means is energized;

    semiconductor switch means;

    said semiconductor switch means having a control input and first and second output terminals for normally providing a current conducting path between said first and second output terminals during the absence of a power failure indication voltage at said control input;

    said control input of said semiconductor switch means being connected to said power failure indication system output for receiving a power failure indication voltage when said DC generator is failing;

    said electrical coil means of said second electromagnetic relay means being connected electrically in series with said first and second output terminals of said semiconductor switch means across said second DC distribution system, wherein said second DC distribution system provides energization current to said electromagnetic coil means of said second electromagnetic relay means in the absence of a power failure indication voltage at said control input of said semiconductor switch means, whereby said second electromagnetic relay means prevents energization of said DC to DC converter means, and said standby power supply cannot supply DC current to said electronic apparatus when said DC generator is functioning;

    said semiconductor switch means being operable to switch into the electrically non-conducting state to discontinue energization of said second relay'"'"'s electromagnetic coil means;

    whereby, in the event said DC generator fails, said electromagnetic coil means of said second electromagnetic relay means deenergizes and said second electromagnetic relay mean'"'"'s break relay contacts complete a current conducting circuit from said rechargeable battery means to said DC to DC converter means prior to deenergization of said electromagnetic coil of said first electromagnetic relay means; and

    said fast pulse mode battery charger is interrupted to discontinue charging of said rechargeable battery means upon deenergization of said first electromagnetic relay means.

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