Set battery charging condition detecting apparatus

• US 20030015995A1
• Filed: 07/01/2002
• Published: 01/23/2003
• Est. Priority Date: 07/12/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Imai, Atsushi, Yamashita, Haruyoshi, Tamura, Hiroshi
• Granted Patent: US 6,563,291 B2
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/12 Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 58/14 Preventing excessive discharging
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/18 of two or more battery modules
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An over-charge determining circuit provided for every unit cell generates, a cell over-charge detection signal which becomes high level when a cell voltage is higher than an upper limit value of an allowable voltage range thereof which is set as the threshold value voltage. The threshold value voltage is changed to a lower limit value of the allowable voltage range with which the cell over-charge detection signal surely becomes high level. Even when an output of an AND circuit for obtaining a logical product of the cell over-charge detection signals should become high, if an over-charge determining circuit of which output is fixed to the low level due to a fault of the like exists, the output of the AND circuit becomes low.

Claims

1. A charging condition detecting apparatus comprising:

a first voltage comparator which is provided for every unit cell forming a chargeable/dischargeable set battery to provide an output of an active level when a cell voltage across the unit cell is higher than a first threshold value voltage set to an upper limit value of an allowable voltage range of the cell voltage;

a second voltage comparator which is provided for every unit cell to provide an output of the active level when the cell voltage of the unit cell is lower than a second threshold value voltage set to a lower limit value of the allowable voltage range;

a first logical sum calculation circuit for generating an over-charge detection signal by obtaining a logical sum of the outputs of the first voltage comparator;

a second logical sum calculation circuit for generating an over-discharge detection signal by obtaining a logical sum of the outputs of the second voltage comparator;

a threshold value voltage changing circuit for changing, depending on an external command, the first threshold value voltage to a first inspection value lower than the lower limit value of the allowable voltage range and also changing the second threshold value voltage to a second inspection value higher than the upper limit value of the allowable voltage range;

a first logical product calculation circuit for generating a first fault detection signal by obtaining a logical product of outputs of the first voltage comparator; and

a second logical product calculation circuit for generating a second fault detection signal by obtaining a logical product of outputs of the second voltage comparator.

2. A charging condition detecting apparatus according to claim 1, further comprising:

a selection circuit is provided for selecting and outputting the over-charge detection signal and the over-discharge detection signal before the first and second threshold value voltages are changed by the threshold value voltage changing circuit, and then selecting and outputting the first and second fault detection signals after the first and second threshold value voltages are changed.

3. A charging condition detecting apparatus according to claim 1, wherein:

each of the first and second voltage comparators is constructed with a voltage dividing circuit for dividing the cell voltage and a comparator for comparing a comparison voltage generated with the voltage dividing circuit with a reference voltage which is set to a value obtained by dividing the upper limit value or lower limit value of the allowable voltage range with a voltage dividing ratio of the voltage dividing circuit; and

the threshold value voltage changing circuit changes the first or second threshold value voltage by changing the voltage dividing ratio of the voltage dividing circuit to relatively change the comparison voltage for the reference voltage.

4. A charging condition detecting apparatus according to claim 1, wherein the first and the second voltage comparators operate by receiving a power source voltage supplied from the unit cells as a comparison object in the voltage comparator or a group of the unit cells to which the unit cell belongs.

5. A charging condition detecting apparatus according to claim 1, wherein the unit cell is a lithium battery constructed with electrodes formed of material which absorbs and releases lithium ions.

6. A charging condition detecting apparatus according to claim 1, wherein the set battery is a vehicle battery loaded as a power source of an electric vehicle or a hybrid electric vehicle.

7. A charging condition detecting apparatus comprising:

a voltage comparator provided for every unit cell forming a chargeable/dischargeable set battery to provide an output of an active level when a cell voltage across the unit cell exceeds, in a side going out of an allowable voltage range, a threshold value voltage which is set to a boundary value of the allowable voltage range of the cell voltage;

a logical sum calculation circuit for obtaining a logical sum of outputs of voltage comparator provided for every unit cell;

a threshold value voltage changing circuit for changing, depending on an external command, the threshold value voltage to an inspection value with which the comparator provides an output of the active level from the boundary value when the unit cell voltage is within the allowable voltage range; and

a logical product calculation circuit for obtaining a logical product of the outputs of the voltage comparator provided for every unit cell.

8. A charging condition detecting apparatus according to claim 7, wherein any one of the boundary value and inspection value is set as an upper limit value of the allowable voltage range and the other is set as a lower limit value of the allowable voltage range.