Circuit for detecting leak from power supply

• US 20030137319A1
• Filed: 11/27/2002
• Published: 07/24/2003
• Est. Priority Date: 03/30/2001
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Furukawa, Kimihiko
• Granted Patent: US 6,833,708 B2
• Time in Patent Office: Days
• US Class Current: 324/771
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• CPC Class Codes: B60L 3/0069 relating to the isolation, e.g. ground fault or leak current
• CPC Class Codes: G01R 19/16538 in AC or DC supplies G01R19/16519 and G01R19/16528 take precedence
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults

Abstract

For use in a power source device having a cell unit (Vb), the invention provides a leak detecting circuit wherein a line P and a line N extending from the cell unit (Vb) are connected to each other by two P-side voltage dividing resistors (R1A, R1B) and two N-side voltage dividing resistors (R2A, R2B), and the midpoint between the P-side resistors (R1A, R1B) and N-side resistors (R2A, R2B) is grounded. The line P and the line N are also connected to each other by first to third auxiliary voltage dividing resistors (R3, R4, R5). The midpoint between the first and second auxiliary resistors (R3) (R4) and the midpoint between the P-side first and second resistors (R1A) (R1B) are connected to each other by a P-side voltage comparison circuit (V1). The midpoint between the second and third auxiliary resistors (R4) (R5) and the midpoint between the N-side first and second resistors (R2A) (R2B) are connected to each other by an N-side voltage comparison circuit (V2).

Claims

1. A leak detecting circuit for a power source device having a cell unit comprising a plurality of cells connected in series, the leak detecting circuit being characterized in that a pair of positive and negative power lines extending from respective opposite electrodes of the cell unit are connected to each other by four voltage dividing resistors (R1A, R1B, R2A, R2B) connected to one another in series, a midpoint between the two voltage dividing resistors (R1A, R1B) arranged on the positive power line side and the two voltage dividing resistors (R2A, R2B) arranged on the negative power line side being grounded, and the potential difference between the positive power line and the midpoint between the two voltage dividing resistors (R1A, R1B) on the positive side and the potential difference between the negative power line and the midpoint between the two voltage dividing resistors (R2A, R2B) on the negative side being compared with respective reference voltages to detect a leak.

2. A leak detecting circuit according to claim 1 wherein the reference voltage on the positive side is set at a potential difference to be produced between the positive power line and the midpoint between the two voltage dividing resistors (R1A, R1B) on the positive side when a leak occurs due to a ground-fault resistance value to be detected, and the reference voltage on the negative side is set at a potential difference to be produced between the negative power line and the midpoint between the two voltage dividing resistors (R2A, R2B) on the negative side when a leak occurs due to a ground-fault resistance value to be detected.

3. A leak detecting circuit according to claim 1 or 2 wherein the pair of positive and negative power lines extending from the respective opposite electrodes of the cell unit are connected to each other by at least three auxiliary voltage dividing resistors (R3, R4, R5) connected to one another in series, and at least two potential reference points are provided between the auxiliary voltage dividing resistors, a positive-side voltage comparison circuit (V1) being interposed between one of the potential reference points and the midpoint between the two voltage dividing resistors (R1A, R1B) on the positive side;

a negative-side voltage comparison circuit (V2) being interposed between the other potential reference point and the midpoint between the two voltage dividing resistors (R2A, R2B) on the negative side.

4. A leak detecting circuit according to claim 3 wherein the positive-side voltage comparison circuit (V1) and the negative-side voltage comparison circuit (V2) each have a sensitivity region in the vicinity of the voltage to be detected and corresponding to a ground-fault voltage value to be judged as producing the leak.

5. A leak detecting circuit according to claim 3 or 4 wherein a positive-side voltage limiter is interposed between the positive power line and a positive terminal of the positive-side voltage comparison circuit (V1) for limiting the potential difference between opposite ends of the voltage limiter to not higher than a predetermined value, and a negative-side voltage limiter is interposed between the negative power line and a negative terminal of the negative-side voltage comparison circuit (V2) for limiting the potential difference between opposite ends of the negative-side voltage limiter to not higher than a predetermined value.