Fault detection system for electric automobile traction system having floating ground

  • US 5,561,380 A
  • Filed: 05/08/1995
  • Issued: 10/01/1996
  • Est. Priority Date: 05/08/1995
  • Status: Expired due to Term
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First Claim
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1. A device for detecting, in an electrically propelled automobile having a chassis, an electrical path to the chassis of the automobile from an electric traction system having a floating ground, comprising:

  • a traction battery;

    a traction motor;

    a positive direct current (DC) line and a negative DC line interconnecting the traction battery and traction motor;

    a positive sampling circuit electrically connected to the positive DC line for generating a first voltage representative of electric current flow from the battery;

    a negative sampling circuit electrically connected to the negative DC line for generating a second voltage representative of electric current flow back to the battery;

    an summing circuit electrically connected to the positive and negative sampling circuits for generating a summed signal representative of the first and second voltages; and

    a comparator electrically connected to the summing circuit for comparing the summed signal to a first reference signal which is proportional to the traction battery voltage and outputting a fault signal in response thereto when an electrical path exists between the chassis and the traction battery.

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