Dc power system and insulation resistance monitor device thereof

Patent metadata

Field	Value
Publication number	US-2025383393-A1
Application number	US-202519235884-A
Country	US
Kind code	A1
Filing date	Jun 12, 2025
Priority date	Jun 13, 2024
Publication date	Dec 18, 2025
Grant date	—

Abstract

A DC power system and an insulation resistance monitor device thereof are provided. The DC power system includes positive, neutral and negative lines, a protective earthing terminal and a grounding resistor. The grounding resistor is electrically connected between the neutral line and the protective earthing terminal. The insulation resistance monitor device includes a first resistor, a first sensing resistor and a first detection circuit. The first resistor is coupled to the positive or negative line. The first sensing resistor is coupled between a second terminal of the first resistor and the protective earthing terminal. The first detection circuit is electrically connected to the first sensing resistor, and is configured to measure a sensing voltage across the first sensing resistor and detect whether an insulation resistance between the protective earthing terminal and any of the positive, neutral and negative lines is abnormal according to the sensing voltage.

First claim

What is claimed is:

1 . An insulation resistance monitor device adapted to a DC power system comprising a positive line, a neutral line, a negative line, a protective earthing terminal, and a grounding resistor, wherein the grounding resistor is electrically connected between the neutral line and the protective earthing terminal, and the insulation resistance monitor device comprises:
a first resistor, having a first terminal coupled to the positive line or the negative line of the DC power system; a first sensing resistor, having a first terminal coupled to a second terminal of the first resistor and a second terminal coupled to the protective earthing terminal; and a first detection circuit, electrically connected to the first and second terminals of the first sensing resistor, and configured to measure a sensing voltage across the first sensing resistor and detect whether an insulation resistance between the protective earthing terminal and any of the positive line, the neutral line, and the negative line is abnormal according to the sensing voltage.

2 . The insulation resistance monitor device according to claim 1 , wherein the first detection circuit is configured to determine that the insulation resistance between the protective earthing terminal and any of the positive line, the neutral line, and the negative line is normal if the sensing voltage is between a first threshold voltage and a second threshold voltage, wherein when a resistance of the grounding resistor is between a lower bound of grounding resistance and an upper bound of grounding resistance, the sensing voltage is between the second threshold voltage and the first threshold voltage correspondingly.

3 . The insulation resistance monitor device according to claim 2 , wherein the first terminal of the first resistor is coupled to the positive line, and when the resistance of the grounding resistor increases from the lower bound of grounding resistance to the upper bound of grounding resistance, the sensing voltage decreases from the second threshold voltage to the first threshold voltage correspondingly.

4 . The insulation resistance monitor device according to claim 3 , wherein the first detection circuit is configured to determine that an insulation resistance between the protective earthing terminal and the neutral line is abnormal if the sensing voltage is between the second threshold voltage and a third threshold voltage, wherein when the resistance of the grounding resistor decreases from the lower bound of grounding resistance to a value close to or equal to zero, the sensing voltage increases from the second threshold voltage to the third threshold voltage correspondingly.

5 . The insulation resistance monitor device according to claim 4 , wherein the first detection circuit is configured to determine that an insulation resistance between the protective earthing terminal and the negative line is abnormal if the sensing voltage is between a fourth threshold voltage and a fifth threshold voltage, and the fourth threshold voltage is greater than the third threshold voltage and less than the fifth threshold voltage, wherein when the insulation resistance between the protective earthing terminal and the negative line decreases from a preset minimum value to a value close to or equal to zero, the sensing voltage increases from the fourth threshold voltage to the fifth threshold voltage correspondingly.

6 . The insulation resistance monitor device according to claim 3 , wherein the first detection circuit is configured to determine that an insulation resistance between the protective earthing terminal and the neutral line is abnormal if the sensing voltage is between the first threshold voltage and a third threshold voltage, wherein when the resistance of the grounding resistor increases from the upper bound of grounding resistance to k times of the upper bound of grounding resistance, the sensing voltage decreases from the first threshold voltage to the third threshold voltage correspondingly, where k is an integer greater than 1.

7 . The insulation resistance monitor device according to claim 6 , wherein the first detection circuit is configured to determine that an insulation resistance between the protective earthing terminal and the positive line is abnormal if the sensing voltage is between a fourth threshold voltage and a fifth threshold voltage, and the fourth threshold voltage is greater than the fifth threshold voltage and less than the third threshold voltage, wherein when the insulation resistance between the protective earthing terminal and the positive line decreases from a preset minimum value to a value close to or equal to zero, the sensing voltage decreases from the fourth threshold voltage to the fifth threshold voltage correspondingly.

8 . The insulation resistance monitor device according to claim 2 , wherein the first terminal of the first resistor is coupled to the negative line, and when the resistance of the grounding resistor increases from the lower bound of grounding resistance to the upper bound of grounding resistance, the sensing voltage increases from the first threshold voltage to the second threshold voltage correspondingly.

9 . The insulation resistance monitor device according to claim 8 , wherein the first detection circuit is configured to determine that an insulation resistance between the protective earthing terminal and the neutral line is abnormal if the sensing voltage is between the second threshold voltage and a third threshold voltage, wherein when the resistance of the grounding resistor increases from the upper bound of grounding resistance to k times of the upper bound of grounding resistance, the sensing voltage increases from the second threshold voltage to the third threshold voltage correspondingly, where k is an integer greater than 1.

10 . The insulation resistance monitor device according to claim 9 , wherein the first detection circuit is configured to determine that an insulation resistance between the protective earthing terminal and the negative line is abnormal if the sensing voltage is between a fourth threshold voltage and a fifth threshold voltage, and the fourth threshold voltage is greater than the third threshold voltage and less than the fifth threshold voltage, wherein when the insulation resistance between the protective earthing terminal and the negative line decreases from a preset minimum value to a value close to or equal to zero, the sensing voltage increases from the fourth threshold voltage to the fifth threshold voltage correspondingly.

11 . The insulation resistance monitor device according to claim 8 , wherein the first detection circuit is configured to determine that an insulation resistance between the protective earthing terminal and the neutral line is abnormal if the sensing voltage is between the first threshold voltage and a third threshold voltage, wherein when the resistance of the grounding resistor decreases from the lower bound of grounding resistance to a value close to or equal to zero, the sensing voltage decreases from the first threshold voltage to the third threshold voltage correspondingly.

12 . The insulation resistance monitor device according to claim 11 , wherein the first detection circuit is configured to determine that an insulation resistance between the protective earthing terminal and the positive line is abnormal if the sensing voltage is between a fourth threshold voltage and a fifth threshold voltage, and the fourth threshold voltage is greater than the fifth threshold voltage and less than the third threshold voltage, wherein when the insulation resistance between the protective earthing terminal

Assignees

• Delta Electronics Inc

Inventors

• Hu Boxue
• Wang Ruxi
• Zhang Chi
• Anup Anurag
• Liu Jian
• Barbosa Peter Mantovanelli

Classifications

• G01R19/1659

  to indicate that the value is within or outside a predetermined range of values (window) (G01R19/16514, G01R19/16519, G01R19/16528 and G01R19/16533 take precedence) · CPC title

• G01R31/40

  Testing power supplies (testing photovoltaic devices H02S50/10) · CPC title

• G01R27/025

  Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters · CPC title

• G01R31/52

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

• G01R31/14 Primary

  Circuits therefor {, e.g. for generating test voltages, sensing circuits (G01R31/1209 - G01R31/1227 take precedence; for testing switches G01R31/327)} · CPC title