Fault detection circuit for sensing leakage currents between power source and chassis
First Claim
1. An electric vehicle fault detection circuit for detecting leakage currents between a DC power source and a chassis of the vehicle, comprising:
- a voltage sensor receiving voltages from the DC power source, said voltage sensor being connected to an analog reference and a chassis ground, said voltage sensor outputting a sensed analog reference signal and a sensed chassis ground signal;
a differential amplifier receiving said sensed analog reference signal and said sensed chassis ground signal from said voltage sensor, said differential amplifier detecting variations of said chassis ground signal from said analog reference signal and outputting a difference signal; and
a voltage comparator unit receiving said difference signal, for determining whether a magnitude of said difference signal output from said differential amplifier exceeds a predetermined threshold value.
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Abstract
A fault detection circuit for detecting leakage currents between a DC power source and chassis of an automobile, includes a voltage sensor coupled to the DC power source, the voltage sensor including an analog reference and a chassis ground. A differential amplifier is coupled to the voltage sensor and detects variations in the analog reference and the chassis ground. A voltage comparator unit determines whether the variations detected in the differential amplifier is above a predetermined threshold value. A built-in test circuit tests whether the fault detection circuit is operating correctly.
135 Citations
19 Claims
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1. An electric vehicle fault detection circuit for detecting leakage currents between a DC power source and a chassis of the vehicle, comprising:
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a voltage sensor receiving voltages from the DC power source, said voltage sensor being connected to an analog reference and a chassis ground, said voltage sensor outputting a sensed analog reference signal and a sensed chassis ground signal; a differential amplifier receiving said sensed analog reference signal and said sensed chassis ground signal from said voltage sensor, said differential amplifier detecting variations of said chassis ground signal from said analog reference signal and outputting a difference signal; and a voltage comparator unit receiving said difference signal, for determining whether a magnitude of said difference signal output from said differential amplifier exceeds a predetermined threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of detecting leakage currents between a DC power source and a chassis of the vehicle comprising the steps of:
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sensing an analog reference signal and a chassis ground signal; detecting a difference between said analog reference signal and said chassis ground signal; determining if a magnitude of said difference exceeds a predetermined threshold value; and outputting a leakage current warning signal when said predetermined threshold value is exceeded. - View Dependent Claims (17, 18, 19)
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Specification