# US 11,906,599 B2 · Earth leakage detecting device, and vehicular power supply system

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- Number: US 11,906,599 B2
- Document ID: US11906599B2
- Status: Granted
- Kind: B2
- Application number: 17/621,185
- Filed: 2020-06-15
- Published: 2022-11-10
- Granted: 2024-02-20
- Earliest claimed: 2019-06-28
- Assignees: Sanyo Electric Co., Ltd.
- Applicants: SANYO Electric Co., Ltd.
- Inventors: Masato Nakayama; Tomonori Kunimitsu; Taisuke Hamada; Jun Asakura
- Web page: https://patentgrep.com/patent/US11906599B2

## CPC

- G01R 31/52: Testing for short-circuits, leakage current or ground faults
- B60L 3/0046: {relating to electric energy storage systems, e.g. batteries or capacitors}
- B60L 3/0069: {relating to the isolation, e.g. ground fault or leak current}
- B60L 3/12: Recording operating variables {; Monitoring of operating variables}
- G01R 31/006: {on road vehicles, e.g. automobiles or trucks (testing of ignition installations peculiar to internal combustion engines F02P17/00)}
- H02H 3/17: by means of an auxiliary voltage injected into the installation to be protected {(using summation current transformers H02H3/33)}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)

## 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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 2)

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.

### Claim 4 (depends on 1)

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.

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 1)

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.

### Claim 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.