Earth leakage detecting device, and vehicular power supply system

Patent metadata

Field	Value
Publication number	US-11906599-B2
Application number	US-202017621185-A
Country	US
Kind code	B2
Filing date	Jun 15, 2020
Priority date	Jun 28, 2019
Publication date	Feb 20, 2024
Grant date	Feb 20, 2024

Abstract

An earth leakage detecting device comprises following elements. A first end of coupling capacitor is connected to a current path of power storage connected to load in a state of being insulated from a ground. Voltage output unit generates a periodic voltage that changes periodically, and applies the periodic voltage to a second end of coupling capacitor via impedance element. Voltage measurer measures a voltage at a connection point between coupling capacitor and impedance element. Earth leakage determiner determines presence or absence of an earth leakage between the current path of power storage and the ground on the basis of the measured voltage. Voltage output unit has a preparation period for constantly outputting a potential between a high-side potential and a low-side potential of the periodic voltage before a measurement period for outputting the periodic voltage.

First claim

The invention claimed is:

1. An earth leakage detecting device comprising:
a coupling capacitor including a first end that is connected to a current path of a power storage, the power storage being connected to a load and insulated from a ground;
a voltage output unit that generates a periodic voltage that changes periodically, the voltage output unit applying the periodic voltage to a second end of the coupling capacitor via an impedance element;
a voltage measurer that measures a voltage at a connection point between the coupling capacitor and the impedance element; and
an earth leakage determiner that makes determination whether or not an earth leakage has occurred based on the voltage measured by the voltage measurer between the current path of the power storage and the ground, wherein
the voltage output unit is provided with (i) a preparation period in which the voltage output unit constantly outputs a potential between a high-side potential and a low-side potential of the periodic voltage, and (ii) a measurement period in which the voltage output unit outputs the periodic voltage, the preparation period being prior to the measurement period,
the earth leakage determiner sets a voltage measured in the preparation period to a reference potential, and
the earth leakage determiner uses at least one of a first peak value or a second peak value in the determination made by the power storage, the first peak value being indicated by a difference between an upper peak value of a voltage waveform measured in the measurement period and the reference potential, the second peak value being indicated by a difference between the reference potential and a lower peak value of the voltage waveform measured in the measurement period.

2. The earth leakage detecting device according to claim 1 , wherein the earth leakage determiner compares the first peak value with the second peak value to evaluate a reliability of the determination.

3. The earth leakage detecting device according to claim 2 , wherein
the voltage output unit constantly outputs an intermediate potential of the periodic voltage in the preparation period, and
the earth leakage determiner invalidates the determination when the first peak value and the second peak value do not correspond to each other.

4. The earth leakage detecting device according to claim 1 , wherein the earth leakage determiner determines that an earth leakage has occurred between the ground and the current path of the power storage when the first peak value is smaller than a first set value, when the second peak value is smaller than a second set value, or when a peak-to-peak value indicated by a difference between the upper peak value and the lower peak value is smaller than a third set value.

5. The earth leakage detecting device according to claim 1 , wherein the voltage output unit suspends a transition to the measurement period when the voltage measurer does not measure a constant potential for a predetermined time or more in the preparation period.

6. A vehicular power supply system comprising:
the earth leakage detecting device described in claim 1 ; and
the power storage that is mounted in the state of being insulated from the chassis ground of the vehicle and supplies power to the load in the vehicle.

7. An earth leakage detecting device comprising:
a coupling capacitor including a first end that is connected to a current path of a power storage, the power storage being connected to a load and insulated from a ground;
a voltage output unit that generates a periodic voltage that changes periodically, the voltage output unit applying the periodic voltage to a second end of the coupling capacitor via an impedance element;
a voltage measurer that measures a voltage at a connection point between the coupling capacitor and the impedance element via a low-pass filter; and
an earth leakage determiner that makes determination whether or not an earth leakage has occurred based on the voltage measured by the voltage measurer between the current path of the power storage and the ground, wherein
the voltage output unit is provided with (i) a preparation period for outputting a high-frequency periodic voltage converted to a constant voltage by the low-pass filter, and (ii) a measurement period for outputting the periodic voltage of a frequency passing through the low-pass filter, the preparation period being prior to the measurement period,
the earth leakage determiner sets a voltage measured in the preparation period to a reference potential, and
the earth leakage determiner uses at least one of a first peak value or a second peak value in the determination made by the power storage, the first peak value being indicated by a difference between an upper peak value of a voltage waveform measured in the measurement period and the reference potential, the second peak value being indicated by a difference between the reference potential and a lower peak value of the voltage waveform measured in the measurement period.

Assignees

• Sanyo Electric Co

Inventors

• Nakayama Masato
• Kunimitsu Tomonori
• Hamada Taisuke
• Asakura Jun

Classifications

• G01R31/52 Primary

  Testing for short-circuits, leakage current or ground faults · CPC title

• B60L3/0046

  relating to electric energy storage systems, e.g. batteries or capacitors · CPC title

• B60L3/0069 Primary

  relating to the isolation, e.g. ground fault or leak current · CPC title

• B60L3/12

  Recording operating variables {; Monitoring of operating variables} · CPC title

• G01R31/006

  on road vehicles, e.g. automobiles or trucks (testing of ignition installations peculiar to internal combustion engines F02P17/00) · CPC title