VOLTAGE MONITOR WITH SELF DIAGNOSTIC FUNCTION

• US 20110074435A1
• Filed: 09/28/2010
• Published: 03/31/2011
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: MIZOGUCHI, Tomomichi
• Granted Patent: US 8,441,263 B2
• Time in Patent Office: Days
• US Class Current: 324/433
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 35/00 Testing or calibrating of apparatus covered by the other groups of this subclass
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

In a voltage monitor, an abnormality detecting unit receives first information outputted from a first obtaining unit and second information outputted from a second obtaining unit, and determines that an abnormality that affects on at least one of first and second diagnostic thresholds arises in the voltage monitor when the first information is different from the second information. The abnormality detecting unit receives a first forced signal outputted from a first forced-output unit and a second forced signal outputted from a second forced-output unit. The abnormality detecting unit determines whether a timing at which the level of the first diagnostic threshold is switched for each step is deviated from a timing at which the level of the second diagnostic threshold is switched for a corresponding step based on a result of a comparison between the first forced signal and the second forced signal.

Claims

1. A voltage monitor for monitoring a voltage of a battery relative to a monitor threshold and for diagnosing the monitor threshold based on each of a first diagnostic threshold and a second diagnostic threshold, the voltage monitor comprising:

a first obtaining unit configured to obtain a first relative relationship between the battery voltage and one of the monitor threshold and the first diagnostic threshold and to output first information indicative of the first relative relationship;

a second obtaining unit configured to obtain a second relative relationship between the battery voltage and one of the monitor threshold and the second diagnostic threshold and to output second information indicative of the second relative relationship;

a threshold switching unit configured to stepwisely switch, by a constant level, a level of each of the first and second diagnostic thresholds when each of the first and second diagnostic thresholds is used by a corresponding one of the first and second obtaining units;

a first forced-output unit configured to forcibly output a first forced signal when a preset period of time has elapsed since a start of the stepwise switch of the first diagnostic threshold by the threshold switching unit;

a second forced-output unit configured to forcibly output a second forced signal when the preset period of time has elapsed since a start of the stepwise switch of the second diagnostic threshold by the threshold switching unit; and

an abnormality detecting unit configured to;

receive the first information outputted from the first obtaining unit and the second information outputted from the second obtaining unit;

determine that an abnormality that affects on at least one of the first and second diagnostic thresholds arises in the voltage monitor when the first information is different from the second information;

receive the first forced signal outputted from the first forced-output unit and the second forced signal outputted from the second forced-output unit; and

determine whether a timing at which the level of the first diagnostic threshold is switched for each step is deviated from a timing at which the level of the second diagnostic threshold is switched for a corresponding step based on a result of a comparison between the first forced signal and the second forced signal.

2. The voltage monitor according to claim 1, wherein each of the first forced signal and the second forced signal has a level that is reversed from one of a low level and a high level to the other thereof.

3. The voltage monitor according to claim 2, wherein the first obtaining unit is configured to output, as the first information, a first signal with a level being shifted from one of a low level and a high level to the other thereof based on the stepwise switch of the level of the first diagnostic threshold, the second obtaining unit is configured to output, as the second information, a second signal with a level being shifted from one of a low level and a high level to the other thereof based on the stepwise switch of the level of the second diagnostic threshold, and each of the first forced signal and the second forced signal has the level that is reversed from the low level to the high level when the level of each of the first and second signals is shifted from the high level to the low level, and has the level that is reversed from the high level to the low level when the level of each of the first and second signals is shifted from the low level to the high level.

4. The voltage monitor according to claim 1, wherein the level of each of the first and second diagnostic thresholds is a voltage level, and the threshold switching unit is configured to stepwisely switch the level of each of the first and second diagnostic thresholds within a usable voltage range of the battery.

5. The voltage monitor according to claim 1, wherein the first obtaining unit comprises:

a first voltage divider configured to output a voltage corresponding to each of the monitor threshold and the first diagnostic threshold as a divided voltage of the voltage of the battery;

a first reference voltage source configured to output a first reference voltage; and

a first comparator configured to;

receive the divided voltage outputted from the first voltage divider and the first reference voltage outputted from the first reference voltage source;

compare the divided voltage with the first reference voltage; and

output a result of the comparison as the first information,

and the second obtaining unit comprises;

a second voltage divider configured to output a voltage corresponding to each of the monitor threshold and the second diagnostic threshold as a divided voltage of the voltage of the battery;

a second reference voltage source configured to output a second reference voltage; and

a second comparator configured to;

receive the divided voltage outputted from the second voltage divider and the second reference voltage outputted from the second reference voltage source;

compare the divided voltage with the second reference voltage; and

output a result of the comparison as the second information,

the threshold switching unit being configured to stepwisely switch a ratio of division of the voltage of the battery to thereby stepwisely switch the level of each of the first and second diagnostic thresholds.

6. The voltage monitor according to claim 1, wherein the first obtaining unit comprises:

a first voltage divider configured to divide a reference voltage to output a divided voltage corresponding to one of the monitor threshold and the first diagnostic threshold; and

a first comparator configured to;

receive the divided voltage outputted from the first voltage divider and the voltage of the battery;

compare the battery voltage with the divided voltage; and

output a result of the comparison as the first information, and the second obtaining unit comprises;

a second voltage divider configured to divide the reference voltage to output a divided voltage corresponding to one of the monitor threshold and the second diagnostic threshold; and

a second comparator configured to;

receive the divided voltage outputted from the second voltage divider and the voltage of the battery;

compare the battery voltage with the divided voltage; and

output a result of the comparison as the second information,

the threshold switching unit being configured to stepwisely switch a ratio of division of the reference voltage to thereby stepwisely switch the level of each of the first and second diagnostic thresholds.

7. A voltage monitor for monitoring a voltage of a battery relative to a monitor threshold and for diagnosing the monitor threshold based on a diagnostic threshold relative to the voltage of the battery, the voltage monitor comprising:

an obtaining unit configured to obtain a relative relationship between the battery voltage and each of the monitor threshold and the diagnostic threshold and to output first information indicative of the relative relationship;

a threshold switching unit configured to stepwisely switch a level of the diagnostic threshold to be used by the obtaining unit by a constant level;

a voltage detecting unit configured to detect the voltage of the battery and to output the voltage of the battery;

an estimating unit configured to receive the voltage of the battery outputted from the voltage detecting unit, compare the voltage of the battery with the diagnostic threshold to estimate the relative relationship between the battery voltage and the diagnostic threshold, and output second information indicative of the estimated relative relationship;

a forced-output unit configured to forcibly output a forced signal when a preset period of time has elapsed since a start of the stepwise switch of the diagnostic threshold by the threshold switching unit, the estimating unit being configured to estimate, based on the estimated relative relationship between the battery voltage and the diagnostic threshold, a timing at which the forced signal is outputted by the forced-output unit; and

an abnormality detecting unit configured to;

receive the first information outputted from the obtaining unit and the second information outputted from the estimating unit;

determine that an abnormality that affects on the diagnostic threshold arises in the voltage monitor when the first information is different from the second information;

receive the forced signal outputted from the forced-output unit; and

determine whether a timing at which the level of the diagnostic threshold is switched for each step is deviated from a normal timing for a corresponding step based on a result of a comparison between a timing of the forced output signal to be inputted to the abnormality detecting unit and the estimated timing at which the forced signal is outputted by the forced-output unit.

8. The voltage monitor according to claim 7, wherein the forced signal has a level that is reversed from one of a low level and a high level to the other thereof.

9. The voltage monitor according to claim 8, wherein the obtaining unit is configured to output, as the first information, a signal with a level being shifted from one of a low level and a high level to the other thereof based on the stepwise switch of the level of the diagnostic threshold, and the forced signal has the level that is reversed from the low level to the high level when the level of the signal is shifted from the high level to the low level, and has the level that is reversed from the high level to the low level when the level of the signal is shifted from the low level to the high level.

10. The voltage monitor according to claim 7, wherein the level of each of the first and second diagnostic thresholds is a voltage level, and the threshold switching unit is configured to stepwisely switch the level of the diagnostic threshold within a usable voltage range of the battery.

11. The voltage monitor according to claim 7, wherein the obtaining unit comprises:

a voltage divider configured to output a voltage corresponding to each of the monitor threshold and the diagnostic threshold as a divided voltage of the voltage of the battery;

a reference voltage source configured to output a reference voltage; and

a comparator configured to;

receive the divided voltage outputted from the voltage divider and the reference voltage outputted from the reference voltage source;

compare the divided voltage with the reference voltage; and

output a result of the comparison as the first information,

the threshold switching unit being configured to stepwisely switch a ratio of division of the voltage of the battery to thereby stepwisely switch the level of the diagnostic threshold.

12. The voltage monitor according to claim 7, wherein the obtaining unit comprises:

a voltage divider configured to divide a reference voltage to output a divided voltage corresponding to each of the monitor threshold and the diagnostic threshold; and

a comparator configured to;

receive the divided voltage outputted from the voltage divider and the voltage of the battery;

compare the battery voltage with the divided voltage; and

output a result of the comparison as the first information,

the threshold switching unit being configured to stepwisely switch a ratio of division of the reference voltage to thereby stepwisely switch the level of the diagnostic threshold.