INSULATION DETECTING DEVICE

• US 20150285851A1
• Filed: 04/03/2015
• Published: 10/08/2015
• Est. Priority Date: 04/03/2014
• Status: Active Grant

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: KAWAMURA, Yoshihiro, ARIGAYA, Ryosuke
• Granted Patent: US 9,874,595 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 3/0069 relating to the isolation, e.g. ground fault or leak current
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/14 Circuits therefor , e.g. for generating test voltages, sensing circuits G01R31/1209 - G01R31/1227 take precedence; for testing switches G01R31/327
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H02H 11/005 in case of too low isolation resistance, too high load, short-circuit; earth fault

Abstract

An insulation detecting device includes a flying capacitor that holds a charged voltage, and a measurement and calculation unit that measures the charged voltage of the flying capacitor and calculates a ground fault resistance formed between a direct-current power supply electrically insulated from a ground, and the ground, based on the measured voltage. The flying capacitor includes one or a plurality of first capacitors, one or a plurality of second capacitors connected with the first capacitor in parallel, and a parallel cancellation switch arranged between the first capacitor and the second capacitor, and which performs parallel connection, and cancellation of the parallel connection, between the first capacitor and the second capacitor. A capacitance of the flying capacitor is variably changed by turning on or turning off of the parallel cancellation switch.

Claims

1. An insulation detecting device comprising:

a flying capacitor configured to hold a charged voltage; and

a measurement and calculation unit configured to measure the charged voltage of the flying capacitor, and calculate a ground fault resistance formed between a direct-current power supply electrically insulated from a ground, and the ground, based on the measured voltage, wherein

the flying capacitor includes one or a plurality of first capacitors, one or a plurality of second capacitors connected with the first capacitor in parallel, and a parallel cancellation switch arranged between the first capacitor and the second capacitor, and which performs parallel connection, and cancellation of the parallel connection, between the first capacitor and the second capacitor, and

a capacitance of the flying capacitor is variably controlled by turning on or turning off of the parallel cancellation switch.

2. The insulation detecting device according to claim 1, further comprising:

a first switch arranged between one end of the flying capacitor and a positive electrode of the direct-current power supply;

a second switch arranged between the other end of the flying capacitor and a negative electrode of the direct-current power supply;

a third switch arranged between the one end of the flying capacitor and the ground; and

a fourth switch arranged between the other end of the flying capacitor and the ground, wherein

the charged voltages of the flying capacitor charged with a first path, a second path, and a third path are measured by the measurement and calculation unit with a fourth path, the first path being formed by turning on of only the first and the second switches, the second path being formed by turning on of only the first and the fourth switches, the third path being formed by turning on of only the second and the third switches, and the forth path being formed by turning on of only the third and the fourth switches, and

the measurement and calculation unit calculates the ground fault resistance, based on the measured voltages of the charged voltages respectively charged in the flying capacitor in the first to the third paths.

3. The insulation detecting device according to claim 1, wherein

the capacitance of the flying capacitor at a time of the cancellation of the parallel connection between the first capacitor and the second capacitor is half or less than the capacitance of the flying capacitor at a time of the parallel connection between the first capacitor and the second capacitor.

4. The insulation detecting device according to claim 1, further comprising:

a measurement mode configured to perform, in a state where the connection cancellation switch is kept off, full charge to the flying capacitor composed of only the first capacitor with the first path formed by turning on of the first and the second switches, measurement of the charged voltage of the flying capacitor fully charged with the fourth path formed by turning on of the third and the fourth switches, and calculation of an output voltage of the direct-current power supply, based on the measured voltage at the full charge measured by the measurement and calculation unit.

5. The insulation detecting device according to claim 2, wherein

the capacitance of the flying capacitor at a time of the cancellation of the parallel connection between the first capacitor and the second capacitor is half or less than the capacitance of the flying capacitor at a time of the parallel connection between the first capacitor and the second capacitor.

6. The insulation detecting device according to claim 2, further comprising:

a measurement mode configured to perform, in a state where the connection cancellation switch is kept off, full charge to the flying capacitor composed of only the first capacitor with the first path formed by turning on of the first and the second switches, measurement of the charged voltage of the flying capacitor fully charged with the fourth path formed by turning on of the third and the fourth switches, and calculation of an output voltage of the direct-current power supply, based on the measured voltage at the full charge measured by the measurement and calculation unit.

7. The insulation detecting device according to claim 3, further comprising:

a measurement mode configured to perform, in a state where the connection cancellation switch is kept off, full charge to the flying capacitor composed of only the first capacitor with the first path formed by turning on of the first and the second switches, measurement of the charged voltage of the flying capacitor fully charged with the fourth path formed by turning on of the third and the fourth switches, and calculation of an output voltage of the direct-current power supply, based on the measured voltage at the full charge measured by the measurement and calculation unit.