JP2754506B2 - Cell short detection charger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cell short detection device for detecting a battery short in a battery.

[0002]

2. Description of the Related Art Generally, a power source is supplied to a system (for example, a computer system) by a battery comprising one cell.
Since it is not possible to obtain a voltage sufficient to supply power to the battery, power is supplied from a battery in which a plurality of cells (for example, eight cells) are connected in series. At this time, even if any of the plurality of cells is short-circuited, the cell is used without any particular detection.

[0003]

Therefore, when any one of a plurality of cells is short-circuited, the following problem occurs.

(1) There is a problem that the voltage of a battery composed of a plurality of cells drops as shown by a dotted line in FIG. 6 and a system driven by the battery goes down.
Further, even when the battery is fully charged, as shown by the dotted line in FIG. 6, the Low battery voltage or the Dead battery voltage is immediately detected, and there is a problem that the system cannot be operated for a long time.

(2) Since the battery capacity is reduced, there is a problem that the system for detecting the remaining battery level cannot accurately detect the remaining battery level (see FIG. 6). (3) A battery with a short-circuited cell has a low voltage as shown by a dotted line in FIG. 6, and thus is determined to be an empty battery and has a problem of being overcharged. Overcharging has the following problems.

[0006] The battery deteriorates. The temperature of the battery itself rises, which adversely affects the surrounding mechanically operating floppy disk or hard disk. (4) When the degree of discharge of a plurality of cells constituting a battery is different, an accurate battery voltage cannot be detected at the beginning of charging, and for example, overdischarge occurs due to a difference in capacity among a plurality of cells connected in series to the battery. The voltage of the cell that has been dropped extremely decreases, the voltage becomes 0 V when the charge amount is zero, and the voltage becomes the reverse voltage when the battery is reversely charged. There was also a problem that it was difficult to determine whether they were different.

An object of the present invention is to solve these problems by detecting a short circuit of a battery and preventing overcharging and system down.

[0008]

Means for solving the problem will be described with reference to FIG. In FIG. 1, a battery 1 is a battery in which a plurality of cells are connected in series, and is a battery for which a cell short is detected.

The battery charge controller 5 detects the battery voltage after a predetermined time t1 has elapsed since the start of charging the battery 1, and this battery voltage is set to a predetermined reference voltage Vb.
If not, a cell short is detected. If a cell short is detected, charging is stopped. The battery voltage is set to a predetermined voltage V before starting charging the battery.
a (where Va <Vb) or more, charging is continued with a small current, and when the voltage exceeds a predetermined voltage Va, charging of the battery is started. Here, the predetermined voltage V
a and Vb are set based on data detected by the temperature sensor.

[0010]

According to the present invention, as shown in FIG. 1, the battery charge controller 5 starts charging the battery 1 for a predetermined time t1.
When the battery voltage after the passage is not higher than the preset reference voltage Vb, it is detected that any of the cells of the battery 1 is short-circuited.

When the battery charge controller 5 detects a short circuit in the cell, the charging of the battery 1 is stopped.
Charging is started when the battery 1 is removed and a new battery 1 is mounted, and when the battery voltage after a lapse of a predetermined time t1 is not equal to or higher than a preset reference voltage Vb, one of the cells of the battery 1 becomes a cell. It detects that it is short-circuited.

Further, the battery charge controller 5 controls the voltage of the battery 1 by a predetermined voltage Va (where Va <V
b) When the battery voltage is not equal to or higher than the predetermined value, charging is continued with a minute current, and when the detected battery voltage exceeds the predetermined voltage Va, charging of the battery 1 is started. Is not detected, any one of the cells of the battery 1 is detected to be short-circuited.
Stops charging the battery 1 when it detects a cell short.

Further, a temperature sensor is provided, and the voltage Va and the voltage Vb are set based on the operating environment temperature detected by the temperature sensor. This is because the voltage of the battery is affected by the temperature.

Therefore, it is possible to detect a short circuit of the battery 1 to prevent overcharging and system down.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of an embodiment of the present invention will be described in order with reference to FIGS.

FIG. 1 is a block diagram showing one embodiment of the present invention.
In FIG. 1, a battery 1 is a battery in which a plurality of cells are connected in series, and as shown in FIG.

The AC adapter 2 generates a DC voltage from a commercial power supply. The DC-DC converter 3 has A
The DC voltage generated by the C adapter 2 is
It is converted to C voltage.

The charging switch 4 is a switch for applying or cutting off the DC voltage generated by the DC-DC converter 3 to the battery 1. The battery charge controller 5 controls the charge of the battery 1. The A / D converter 6 converts the voltage of the battery 1 into a digital voltage and takes in the digital voltage. ON / OFF to control charging, to detect a cell short of the battery 1, and to turn the charging switch 4 OFF when detecting a cell short.
F to stop charging, notify the user of a cell short by sending a cell short notification 8,
When the battery 1 is removed and another battery 1 is mounted, the cell short flag 51 is reset to start discharging (described later with reference to FIG. 2).

The cell short flag 51 is turned on when the battery charge controller 5 detects a short circuit of the battery 1 and sets the fact that the short circuit is detected. When the cell short flag 51 is set to ON, the charging switch 4 is turned OFF and the battery 1
To stop charging the cell, or perform a cell short notification 8.

The A / D converter 6 converts the voltage of the battery 1 into a digital voltage. The counter 7
The time is counted, and the battery charge controller 5 turns on the charge switch 4 to supply a current from the DC-DC converter 3 to the battery 1 to measure a predetermined time t1 or the like.

When the battery charge controller 5 detects a cell short, the cell short notification 8 notifies the user that a cell short has been detected (for example, the display of FIG. ).

Next, the operation of the configuration of FIG. 1 will be described in detail according to the order shown in the flowchart of FIG. In FIG. 2, S0 sets Va and Vb by the temperature sensor.
Since the voltages Va and Vb are affected by the temperature of the battery, the voltages Va and Vb are set based on the temperature detected by the temperature sensor.

In S1, the cell short flag 51 is ON.
Or OFF. Since it is initially OFF, S
Proceed to 2. On the other hand, if a cell short has already been detected in S5, it is ON and the process proceeds to S8.

In step S2, it is determined whether the battery is charged. YES
In the case of, it is determined at S3 whether or not the charging counter is being operated.
In the case of ES, the charging time is counted in S4 (the charging time is counted by the counter 7 in FIG. 1), and the process returns to S0. In the case of NO, the process proceeds to S5. On the other hand, in the case of NO, since the battery is not being charged, the process returns to S0.

A step S5 decides whether or not a cell short is detected. In this cell short detection, for example, as shown in FIG. 3A, when the battery voltage after a lapse of a predetermined time t1 from the start of charging the battery 1 is not higher than or equal to a preset reference voltage Vb, a cell short is detected. Is detected. If the cell is short, the process proceeds to S7. If it is not a cell short, the cell short flag 51 is turned off in S6, and S0
Return to

At S7, since the cell short is detected at S5, the battery charging is stopped and the cell short flag 51 is set to ON. A step S8 decides whether or not the battery has been removed. In the case of YES, since the battery 1 has been removed by the user and another battery 1 has been mounted, the cell short flag 51 is turned off in S9, and the battery 1 can be charged. On the other hand, in the case of NO, since the battery 1 is removed and the battery 1 is not replaced, the cell short flag 51 is turned on and the battery 1 is kept in a state where charging is not possible, and the battery 1 is removed and the battery 1 is waited for replacement.

As described above, the battery charge controller 5 turns on the charge switch 4 to start charging the battery 1. When the battery voltage does not become equal to or higher than the reference voltage Vb even after the lapse of the predetermined time t1, any one of the batteries 1 It is detected that one of the cells is short-circuited (cell short-circuit), and the charge switch 4
OFF to stop charging and cell short flag 5
Turn 1 ON. Then, in response to the display or sounding of the cell short-circuit, the cell short flag 51 is reset to OFF in response to the user removing the battery 1 and attaching the new battery 1, and charging is started. . As a result, it is possible to avoid the danger of the system going down due to a decrease in the battery voltage due to the use of the battery 1 in which the cell is short-circuited, and to accurately display the remaining battery level.

FIG. 3 is a diagram for explaining the operation of the present invention. FIG.
(A) shows a constant current charging voltage curve. The horizontal axis is time t
And the vertical axis represents the voltage of the battery 1. Where Vb
Is a reference voltage, and t1 is a charging time for detecting a cell short. The solid line is the charging voltage curve of the normal battery 1, and the dotted line is the charging voltage curve of the battery 1 with a short-circuited cell.

The cell short detection is performed by detecting the battery 1 with a constant current.
Of the battery 1 (battery voltage) when a predetermined time t1 (for example, several minutes to several tens of minutes) has elapsed since the start of charging of the battery 1
Is detected, and when the detected battery voltage does not exceed the reference voltage Vb measured in advance, it is detected that the cell is short-circuited.

FIG. 3B shows a fast charging voltage curve. The horizontal axis represents time t, and the vertical axis represents the voltage of the battery 1. Here, Vb is a reference voltage, and t2 (may be shared with t1) is a charging time for detecting a cell short. The solid line is the charging voltage curve of the normal battery 1, and the dotted line is the charging voltage curve of the battery 1 with a short-circuited cell.

The cell short detection is performed by detecting the battery 1 with a large current.
For a predetermined time t2 (where t2 <t
1, for example, several minutes), the voltage (battery voltage) of the battery 1 is detected, and when the detected battery voltage does not exceed the reference voltage Vb measured in advance, it is determined that the cell is short-circuited. To detect. In the case of rapid charging, the charging voltage changes in a mountain-like manner as shown in the figure. Therefore, the voltage is detected after t2 to check whether the voltage does not exceed the reference voltage Vb. I do.

FIG. 3C shows an example of a battery in which a cell is short-circuited. Here, the hatched cells are short-circuited. Assuming that the voltage of one cell constituting the battery 1 is v1 and the number of cells is n, the voltage V of the normal battery 1 is V = n × v1 (1). The voltage Vs of the battery 1 when one cell constituting the battery 1 is short-circuited is as follows: Vs = (n−1) × v1 = n × v1−v1 = V−v1 (2) When V is obtained from this equation (2), V = Vs + v1 (3)

Accordingly, when the cells constituting the battery 1 are short-circuited, the voltage at the time of charging is reduced as shown in FIGS. 3A and 3B, so that the battery voltage after the predetermined time t1 or t2 has elapsed. However, when the reference voltage Vb does not exceed the previously measured reference voltage Vb, it can be easily detected as a cell short.

FIG. 4 shows another operation explanatory diagram of the present invention.
This is because when the voltage when the battery 1 is charged is low (for example, as described with reference to FIG. 3A), even if the battery 1 is charged with a constant current for a predetermined time t1, a predetermined voltage Va lower than the reference voltage Vb is applied. If the voltage does not exceed the predetermined voltage Va, trickle charging (charging with a small current) is performed until the voltage exceeds the predetermined voltage Va. This trickle charge is performed and a predetermined voltage V
a, normal charging is performed for a predetermined time t1,
If the battery voltage at this time does not exceed the reference voltage Vb, a cell short is detected. Thus, the predetermined voltage Va
Performing trickle charging when Va <Vb is not satisfied is not possible because the accurate battery voltage cannot be detected at the beginning of charging if the degree of discharge of a plurality of cells constituting the battery 1 is different. Thus, an accurate battery voltage can be detected.

FIG. 5 shows an example of a cell short display according to the present invention. This is a display for notifying the user that a cell short has occurred when the battery charge controller 5 detects a cell short, and prompting the user to replace the battery 1.

FIG. 5A shows a display example when charging is started. At this time, the characters “CHARGE” and “BATT” are displayed to indicate that the battery 1 is being charged, and a state in which the battery 1 has not yet been charged without displaying any of the four divided parts of the battery 1 is displayed.

FIG. 5B shows the state during charging and the counting of charging time. At this time, the characters “CHARGE” and “BATT” are displayed to indicate that the battery 1 is being charged. One of the four divided battery 1s is displayed, indicating that the battery 1 has been charged a little.

FIG. 5C shows a display example when a cell short is detected. At this time, since charging has been suspended,
The display of CHARGE and BATT is turned off, the both ends of the four divisions of the battery 1 are displayed, and the center two are blinked to indicate that a cell short has been detected.

[0039]

As described above, according to the present invention,
When the battery voltage after a lapse of a predetermined time t1 from the start of charging the battery is not higher than or equal to a preset reference voltage Vb, a configuration is adopted which detects that any of the cells of the battery is short-circuited. In addition, it is possible to detect a cell short-circuit of the battery 1 and to notify the user by displaying that the cell short-circuit is detected or sounding, and to replace the battery 1 having the cell short-circuit, thereby preventing a voltage drop. As a result, (1) when the system is driven by the battery 1 in which the cell is short-circuited, the voltage of the battery 1 is low and the system is shut down. The system can be prevented from going down.

(2) When detecting and displaying the remaining battery level, if the cell is short-circuited, the accurate remaining battery level cannot be calculated. Therefore, the battery must be replaced with a normal battery, and the accurate remaining battery level can be calculated. You can do so.

(3) If there is a cell short, battery 1
Is overcharged, causing a rise in temperature and adverse effects on the floppy disk and the hard disk. Therefore, replacement of the battery with a normal battery can be prevented, and this adverse effect can be prevented. (4) When a plurality of cells constituting a battery have different degrees of discharge, an accurate battery voltage cannot be detected at the beginning of charging. However, according to the present invention, charging is continued with a small current and all cells (voltage (0 or reverse voltage cell) rises to a substantially normal cell voltage, and an accurate battery voltage can be detected. This makes it possible to judge a cell short in a state where an accurate battery voltage can be detected, and eliminate an erroneous judgment of a cell short due to a difference in cell capacity.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the present invention.

FIG. 3 is an operation explanatory diagram of the present invention.

FIG. 4 is another operation explanatory diagram of the present invention.

FIG. 5 is an example of a cell short display according to the present invention.

FIG. 6 is a discharge voltage curve of a battery.

[Explanation of symbols]

 1: Battery 2: AC adapter 3: DC-DC converter 4: Discharge switch 5: Battery charge controller 51: Cell short flag 6: A / D converter 7: Counter 8: Cell short notification

Claims (2)

(57) [Claims] 1. A battery is charged by detecting a short circuit of a battery cell .
In the cell short detection charging device that, supplying charging current from the charging power source to the battery
Or charge switch to cut off and convert analog voltage of the above battery to digital voltage
An A / D converter for, at the start of charging the battery in the ON the charging switch
Means that continued charging at a minute current when the digital battery voltage detecting the back <br/> Teri voltage detection is not the reference voltage V a or more set in advance, was detected at the time of the lapse of the predetermined time t the digital after the predetermined time t1 has elapsed starting charging <br/> battery and the charging switch is turned oN when the battery voltage of the digital exceeds the predetermined voltage V a
The battery voltage of the battery is detected and the detected battery voltage
Is equal to or higher than a preset reference voltage Vb (Vb> Va)
A short-circuit detection charging device, comprising: a battery charging controller having means for charging the battery . 2. A temperature sensor for detecting a use environment temperature of the battery, and means for setting the voltage Va and the voltage Vb based on the use environment temperature detected by the temperature sensor. The charging device according to claim 1, wherein