JP2985613B2 - Storage battery device with short-circuit cell number detection function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage battery device having a function of detecting the number of short-circuited cells, comprising a nickel-cadmium storage battery or the like and a device for detecting the number of short-circuited cells for detecting the number of cells in which a cell short-circuit has occurred.

[0002]

2. Description of the Related Art A nickel-cadmium storage battery is a secondary battery in which an alkaline electrolyte is filled between a nickel electrode on a positive electrode side and a cadmium electrode on a negative electrode via a separator. The storage battery device is configured to obtain a high voltage by connecting a plurality of cells of such a nickel cadmium storage battery in series. In some of the storage battery devices, a short-circuit cell number detection device is provided to detect the number of cells of a nickel cadmium storage battery in which a cell short circuit has occurred. In addition to this, a dry-up detection device is provided to detect dry-up due to exhaustion of the electrolyte,
In some cases, an integrated battery capacity calculating device is provided, and the integrated battery capacity indicating the battery capacity actually stored at that time in the nickel cadmium storage battery is calculated at any time.

Cell short-circuiting is a phenomenon in which a storage battery device repeatedly charges and discharges to generate needle-like metal cadmium in a separator inside a cell of a nickel cadmium storage battery, which causes a short circuit between positive and negative electrode plates. is there. When such a cell short circuit occurs, the cell no longer serves as a storage battery. Therefore, the short-circuit cell number detection device of the storage battery device measures the terminal voltages of all cells connected in series in the storage battery device during charging, and this terminal voltage becomes abnormally low due to a decrease in the internal resistance of some cells. In this case, it is determined that a cell short circuit has occurred, and the number of cells in which the cell short circuit has occurred is detected. Further, when the cell short circuit occurs in a large number of cells, the storage battery device cannot supply a sufficient voltage, so that the battery is notified to the outside as a battery abnormality.

[0004] Dry-up is a phenomenon in which the electrolyte inside the cells of a nickel-cadmium storage battery is gasified and exhausted due to overcharging or the like, and the internal resistance rises abnormally. Then, the dry-up detection device of the storage battery device measures the terminal voltages of all cells connected in series in the storage battery device during charging, and when this terminal voltage becomes abnormally high due to an increase in the internal resistance of some cells. This dry-up is detected. Also, if such dry-up occurs even in one cell, the storage battery device cannot supply a sufficient current due to an increase in internal resistance and it becomes difficult to charge the battery. Notify externally that the battery is abnormal.

[0005] The integrated battery capacity is, for example, a value when the nickel cadmium storage battery is in a completely discharged state is set to 0 mAmsec (milliamp millisecond). This is a value calculated by repeating the integration process of subtracting the discharge capacity obtained by time-integrating the current. Therefore, this integrated battery capacity represents the battery capacity actually stored in the storage battery device at that time, and at the time of charging, it can be used to determine the percentage of the rated battery capacity and to indicate the progress of charging, In addition, at the time of discharging, the integrated battery capacity indicates the remaining capacity as it is, and the remaining available battery capacity can be notified without performing charging thereafter. However, since errors are accumulated when such integration of the charge capacity and the discharge capacity is repeated, the integrated battery capacity calculation device of the storage battery device is, for example, one that is completely discharged when the terminal voltage of the nickel cadmium storage battery falls below a predetermined voltage. Assuming
The integrated battery capacity at that time is reset to 0 mAm seconds to initialize the integration.

[0006]

However, the terminal voltage of a nickel-cadmium storage battery is affected by the magnitude of the charging current at the time of charging, and when a large charging current is supplied for rapid charging, this terminal voltage is reduced. Will also rise. However, the conventional short-circuit cell number detecting device sets the cell voltage per cell as a reference of the cell short-circuit to a constant value, and the measured terminal voltage indicates the cell voltage and the rated cell number indicating the number of mounted cells. The number of short-circuit cells was detected based on the number of cells lower than the product of the short-circuit cells.If the charge current is small, the number of short-circuit cells is excessively detected. There is a problem that the number of cells is detected less than the actual number. And
When the number of short-circuit cells becomes inaccurate in this way, there is a possibility that a battery abnormality is erroneously detected.

The dry-up detecting device and the integrated battery capacity calculating device calculate the cell voltage per cell by dividing the measured terminal voltage by the number of cells of the storage battery device, and if the cell voltage is equal to or higher than a predetermined value. In addition to detecting dry-up, if the value is equal to or less than a predetermined value, a complete discharge state is detected and the integrated battery capacity is reset to 0 mAm seconds. It is necessary to subtract the number of short-circuited cells that have already caused a cell short-circuit from the rated number of cells. Therefore, when the number of short-circuit cells is incorrect, a problem arises that the detection of dry-up by the dry-up detector and the detection of the complete discharge state by the integrated battery capacity calculator become unreliable. .

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a storage battery device with a short-circuit cell number detection function capable of obtaining an accurate short-circuit cell number based on a predicted cell voltage per cell according to a charging current. And

[0009]

According to a first aspect of the present invention, there is provided a storage battery device having a short-circuit cell number detection function, comprising: a chargeable storage battery comprising a plurality of cells; and a charging current flowing into the storage battery during charging. Charging current detecting means for detecting the terminal voltage of the storage battery at the time of charging, a voltage value set in advance as an initial value for estimating the cell voltage, the charging current detected by the charging current detecting means A predicted cell voltage calculating means for converting the converted voltage value as a predicted cell voltage for predicting a cell voltage per cell based on a predetermined conversion procedure of setting a higher voltage value as the charging current increases. A rated cell number recording means for recording the rated cell number of the storage battery; a predicted cell voltage calculated by the predicted cell voltage calculation means and a rated cell recorded in the rated cell number recording means. The number of short-circuit cells is obtained by subtracting the terminal voltage detected by the terminal voltage detection means from the product of the numbers and dividing the result of the subtraction by the predicted cell voltage. .

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the storage battery device with the short-circuit cell number detection function rounds down the value below the decimal point of the short-circuit cell number calculated by the short-circuit cell number calculation means to convert the short-circuit cell number into an integer. The present invention is characterized in that means for converting the number of short-circuit cells to integers are provided.

[0011]

The rechargeable storage battery provided in the storage battery device with the function of detecting the number of short-circuit cells according to the present invention includes all secondary batteries such as nickel cadmium storage batteries.

The charging current detecting means includes, for example, a resistor having an extremely low resistance value connected in series to the storage battery, and measures a charging current by measuring a voltage drop in the resistor due to a current flowing in the storage battery. Can be detected. The terminal voltage detecting means detects the terminal voltages of the entire plurality of cells of the storage battery during the charging.

The predicted cell voltage calculating means presets a cell voltage predicted when the charging current is 0 A, for example, as an initial value, and, based on the charging current detected by the charging current detecting means, increases as the charging current increases. The predicted cell voltage is calculated according to a predetermined conversion procedure that results in a voltage value higher than the initial value. The predicted cell voltage is obtained by predicting the cell voltage per cell according to the magnitude of the charging current for a cell in which no cell short circuit has occurred. Therefore, if no cell short-circuit has occurred, the value obtained by multiplying the predicted cell voltage by the rated cell number of the storage battery mounted on the storage battery device should match the terminal voltage detected by the terminal voltage detection means during charging. . The rated cell number of this storage battery device is recorded in the rated cell number recording means. Since the rated cell number is fixed for each type of storage battery device, a read-only recording unit can be used as the rated cell number recording unit.

The conversion procedure executed by the predicted cell voltage calculation means includes, in addition to a procedure of performing a predetermined calculation using the charging current as a parameter, a table of predicted cell voltage values set in advance for each charging current value. It may be a procedure for referring to and calculating a predicted cell voltage corresponding to the charging current,
The predicted cell voltage can be calculated by a method other than the original arithmetic processing. Also, this conversion procedure should not result in a large predicted charging cell voltage having a lower predicted cell voltage than a smaller charging current for any two types of charging currents. In some cases, the same predicted cell voltage may be obtained for large and small charging currents.

The short-circuit cell number calculating means first subtracts the terminal voltage detected by the terminal voltage detecting means from the product of the predicted cell voltage calculated by the predicted cell voltage calculating means and the rated cell number recorded in the rated cell number recording means. I do. That is, as described above, if no cell short-circuit has occurred, the result of this subtraction should be almost 0 V. However, if a cell short-circuit has occurred, the internal resistance of the cell in which the cell short-circuit has occurred is almost zero. Since it is 0Ω, the result of the subtraction shows a large voltage value in proportion to the number of short-circuit cells. Therefore, the short-circuit cell number calculation means can obtain the short-circuit cell number by further dividing the subtraction result by the predicted cell voltage.

As a result, according to the storage battery device with the short-circuit cell number detecting function of the first aspect, a predicted cell voltage is calculated by estimating the cell voltage per cell according to the magnitude of the charging current.
Since the number of short-circuited cells is calculated from the actual terminal voltage based on the predicted cell voltage, the accurate number of short-circuited cells can be detected.

The calculation procedure in the short-circuit cell number calculation means or the like is not particularly limited as long as the calculation is substantially the same. That is, for example, it is assumed that the predicted cell voltage calculation means calculates a predicted terminal voltage by predicting a terminal voltage when all cells are connected in series, and the terminal voltage detection means detects the shorted cell number calculation means from the predicted terminal voltage. The terminal voltage may be subtracted, the result of the subtraction may be further divided by the predicted terminal voltage, and the number of short-circuit cells may be obtained by multiplying by the rated cell number recorded in the rated cell number recording means.

Since the number of short-circuit cells detected here does not change frequently, it is usually necessary to perform one detection only during charging, for example, when the charging capacity exceeds a predetermined ratio of the rated battery capacity. To do. Further, in order to further increase the detection accuracy of the number of short-circuit cells, the terminal voltage is detected by the terminal voltage detection means a plurality of times, and the average value thereof is employed to eliminate the influence of noise or to detect the short-circuit cell as a detection result. If the same value is not detected a plurality of times, the number may not be adopted as a valid result to avoid erroneous detection.

In the storage battery device with a short-circuit cell number detecting function according to a second aspect, the short-circuit cell number integer converting means converts the short-circuit cell number calculated by the short-circuit cell number calculating means into an integer. In an actual operation by the short-circuit cell number calculating means, a fraction after the decimal point usually occurs in the result. However, since a cell short-circuit is a phenomenon in which the positive and negative electrode plates in the cell are short-circuited, it is unlikely that the inside of the cell connected in series is further divided and short-circuited, and thus the short-circuited cell is not considered. Numbers are also usually integers. Therefore, in claim 2, by converting the number of short-circuit cells calculated by the short-circuit cell number calculation means into an integer, the number of short-circuit cells can be obtained as an integer value as in a general concept.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 to 5 show an embodiment of the present invention. FIG. 1 is a flowchart showing the operation of the short-circuit cell number detecting process shown in FIG. 2, and FIG. 2 is an interrupt routine of the microcomputer. FIG. 3 is a block diagram showing the configuration of the storage battery device, FIG. 4 is a diagram showing the relationship between the charging current and the predicted cell voltage, and FIG.
4 is a memory map of a recording area of the number of short-circuit cells in a PROM.

The storage battery device of this embodiment will be described in the case where the arithmetic control unit of the short-circuit cell number detecting device is constituted by a one-chip microcomputer.

As shown in FIG. 3, the storage battery device includes a nickel cadmium storage battery 1 and a microcomputer board 2 housed in a case. The nickel cadmium storage battery 1 has a plurality of cells 1a connected in series. The positive electrode is connected to a positive terminal 3 of the storage battery device, and the negative electrode is connected to a negative terminal 5 via a shunt resistor 4. The charging and discharging of the storage battery device is performed through the positive terminal 3 and the negative terminal 5. The shunt resistor 4 is an extremely low-resistance resistor having a resistance value of about several mΩ, and functions as a current detector for detecting the magnitude of the current flowing therethrough. In this storage battery device, a thermostat 6 and a thermistor 7 are arranged in the vicinity of the nickel-cadmium storage battery 1 so that their respective conduction states and resistance values can be read from external terminals.
Since the thermostat 6 is shut off when the temperature rises to a predetermined value or more, the terminal state of charge of the nickel cadmium storage battery 1 can be detected by reading out this conduction state from the outside. Since the resistance value of the thermistor 7 changes according to the temperature of the nickel-cadmium storage battery 1, the resistance value can be read from the outside to be used for detecting the timing of completion of charging and the like.

The microcomputer board 2 is a circuit board on which the microcomputer 2a and its peripheral circuits are mounted. The microcomputer 2a has analog ports AD1 to AD3 for inputting analog signals and performing AD conversion. The terminal voltage of the nickel cadmium storage battery 1 is input to the first analog port AD1 via the terminal voltage input circuit 2b, and the voltage drop due to the charging current of the shunt resistor 4 is input to the second analog port AD2. Is input via the charging current input circuit 2c, and a voltage drop due to the discharging current of the shunt resistor 4 is input to the third analog port AD3 via the discharging current input circuit 2d. Terminal voltage input circuit 2b
Is an interface circuit for converting the terminal voltage of the nickel cadmium storage battery 1 into a voltage range in which AD conversion can be performed by resistance division and sending it to the first analog port AD1. The charging current input circuit 2c and the discharging current input circuit 2d
An inverting amplifier and a non-inverting amplifier that obtain a predetermined gain by applying negative feedback to an operational amplifier (operational amplifier). The inverting amplifier and the non-inverting amplifier convert voltage drops corresponding to a charging current and a discharging current into voltage ranges in which AD conversion can be performed, respectively. Interface circuit for sending the signals to the second and third analog ports AD2 and AD3. However, the charging current input circuit 2c outputs a positive voltage when the charging current flows through the shunt resistor 4,
The discharge current input circuit 2d outputs a positive voltage when a discharge current flows through the shunt resistor 4, and the negative voltage is treated as a current value of 0A. A charging current and a discharging current are separately input to the analog ports AD2 and AD3. As a result, the values of the terminal voltage, the charging current and the discharging current of the nickel cadmium storage battery 1 are input to these analog ports AD1 to AD3, respectively, and are converted into digital signals internally. The value of the terminal voltage input to the first analog port AD1 actually includes the voltage drop of the shunt resistor 4, but this voltage drop can be almost ignored.

The microcomputer 2a has IO ports D0 to D10 for performing digital input / output.
An EEP as an external storage device is connected to the IO ports D0 to D3.
The ROM 2e is connected. The EEPROM 2e is an EEPROM [Electrically Erasable Programmable] which is a nonvolatile semiconductor memory device which can be electrically written.
Read-Only Memory], and the IO ports D0 to D
3, data can be read from and written to the EEPROM 2e. This EEPRO
In M2e, battery information unique to the battery device, such as the rated battery capacity and the number of rated cells, is written and stored in advance, and dynamic battery information, such as the number of short-circuit cells, is also written and updated as needed. . 5 for IO ports D4 to D8
An LED array 2f having a plurality of LEDs [Light Emitting Diodes] is connected so that the LEDs corresponding to each of the IO ports D4 to D8 can be arbitrarily turned on. A communication terminal 9 which is an external terminal of the storage battery device is connected to the IO port D9, and communication with a charger or the like can be performed via the communication terminal 9. An operation switch 8 provided with an operation unit on the surface of the storage battery device is connected to the IO port D10 so that the operation of the operation switch 8 can be read.

The microcomputer 2a is supplied with a constant voltage power supply from the nickel cadmium storage battery 1 via a power supply circuit 2g. Also, an AD conversion circuit and EEPROM in the microcomputer 2a are used.
The M2e and the LED array 2f are also supplied with power from the nickel-cadmium storage battery 1 via a power supply circuit (not shown). However, the power supply of the AD conversion circuit and the like is controlled by the microcomputer 2a so as to be supplied only when necessary, so that useless power is not consumed.

The operation of the short-circuit cell number detecting device of the storage battery device having the above configuration will be described with reference to the flowcharts of FIGS.

The microcomputer 2a has an internal PR.
The control operation is performed by the CPU [Central Processing Unit] performing input / output of each of the ports AD1 to AD3 and D0 to D10 according to the program stored in the OM [Programmable Read-Only Memory]. The microcomputer 2a has a timer interrupt function therein, and can call a program interrupt routine by a hardware interrupt at each time interval set in the timer. Then, the short-circuit cell number detecting device is realized by this interrupt routine.

This interrupt routine is set so as to be called at a relatively long timer interval T1 in order to suppress power consumption when the control is in a standby state. And when this interrupt routine is called,
As shown in FIG. 2, in the first step (hereinafter referred to as "S"), detection is performed by AD-converting the value of the charging current input to the analog port AD2 (S
1). Next, it is checked whether or not the state of charge has been set (S2). If the state of charge has not been set,
It is determined whether the value of the detected charging current is equal to or more than the charging start current Imin (S3). Then, the charging start current Imin
If it is determined that the current time is less than the above, it indicates that the control is in the normal standby state or another state and charging has not been started, and the interrupt routine is immediately terminated.

Here, when the charging of the storage battery device is started, it is determined that the charging current has become equal to or more than the charging start current Imin in the process of S3 of the interrupt routine called first after that. The interruption time is set to a timer time interval T2 shorter than the timer time T1 (S4), and the charging state is set (S4).
5) The control is shifted from the standby state to the charging state. Then, the charging capacity is calculated by multiplying the detected charging current value by the timer time T2, which is the time interval of the timer interrupt (S6). If the charging capacity calculated here is integrated, it means that the charging current has been integrated over time, so that the charge amount accumulated in the nickel-cadmium storage battery 1 by charging can be detected. Further, at this time, if the charging current is multiplied by a charging efficiency that changes according to the magnitude of the charging current and the number of times of charging, more accurate charging capacity can be calculated. The reason for setting the timer interrupt time in the charging state to the timer time interval T2 shorter than the timer time interval T1 in the standby state is to accurately detect the charging capacity based on the charging current. It is possible to cope with the case where the current is unstable or changes significantly.

When the charge capacity is calculated as described above, the RAM [Random] in the microcomputer 2a is used.
The value of the charging current stored in the Access Memory] and the integrated battery capacity are updated (S7), and the number of short-circuited cells is detected (S8). The update of the value of the charging current in S7 is performed by rewriting the value stored in the RAM to a newly detected value. In addition, the integrated battery capacity is updated by first adding the previously calculated charged capacity to the previous integrated battery capacity read from the RAM, and writing the addition result to the RAM as a new integrated battery capacity.

The process of detecting the number of short-circuited cells in S8 is a process of detecting the number of cells 1a in which a cell short-circuit has occurred among the plurality of cells 1a of the nickel cadmium storage battery 1 and recording the number in the EEPROM 2e. However, the detection of the number of short-circuit cells
It is designed to be performed only once per charge. That is, as shown in FIG.
The integrated battery capacity before updating by the process of
Is determined to be less than R% of the rated battery capacity stored in (S21), and then it is determined whether the integrated battery capacity after the update in the process of S7 is equal to or more than R% of the rated battery capacity. (S22). If the integrated battery capacity before the update is not less than R% of the rated battery capacity or the integrated battery capacity after the update is not more than R% of the rated battery capacity,
This short-circuit cell number detection processing in S8 is immediately terminated. However, the integrated battery capacity before update is less than R% of the rated battery capacity, and the integrated battery capacity after update is R% of the rated battery capacity.
%, That is, when the integrated battery capacity just exceeds R% of the rated battery capacity due to charging, the number of short-circuit cells is detected only once. The number of short-circuited cells is detected by first performing A / D conversion on the value of the terminal voltage input to the analog port AD1 (S23) and predicting from the internal PROM based on the previously detected charging current value. The cell voltage is read (S24).

In the detection of the terminal voltage in step S23, in order to avoid the influence of noise, the terminal voltage value input to the analog port AD1 is continuously AD-converted and read a plurality of times.
An average of the remaining values excluding the maximum value and the minimum value of these values is obtained, and this is used as an effective terminal voltage. Also, one cell 1 of the nickel-cadmium storage battery 1 at the time of charging
The cell voltage of a is 1.3 if this cell 1a is normal.
The higher the charging current is, the higher the voltage is in the range of about V to 1.6 V. Therefore, in this embodiment, this one cell 1
The cell voltage of “a” is approximated by a linear expression of the charging current I as the predicted cell voltage Vsel, and is obtained by calculating the expression Vsel = Vsel0 + kI. Here, Vsel0 is the initial value of the virtual predicted cell voltage when the charging current I is 0A. Also, k
Is a positive constant close to zero. Accordingly, the relationship between the charging current and the predicted cell voltage is represented by a straight line that rises to the right as shown in FIG. 4, and as the charging current increases, the predicted cell voltage gradually increases. In the process of S24, the predicted cell voltage can be calculated by calculating the equation Vsel = Vsel0 + kI based on the value of the charging current. However, since such an operation imposes a useless load on the microcomputer 2a, a ROM table method for reading out a predicted cell voltage stored in an internal PROM in advance is used here. That is,
The charging current is classified into appropriate ranges, and the predicted cell voltage for the charging current representative of each range is calculated in advance and written in the PROM. Of the predicted cell voltage.

When the predicted cell voltage is read as described above, the predicted cell voltage, the previously detected terminal voltage, and E
The number of short-circuited cells is calculated from the rated number of cells stored in the EPROM 2e (S25), and the detected number of short-circuited cells is calculated as EEP.
The data is recorded in the ROM 2e (S26), and the short-circuit cell number detection processing in S8 is ended.

In the process of S25, the predicted cell voltage is set to Vsel
, The terminal voltage V and the rated cell number N, the short-circuit cell number NS is expressed by the following equation: NS = INT ((N × Vsel−V) / Vsel
). That is, the sub-expression (N × Vsel
−V) predicts the terminal voltage by the product of the rated cell number N and the predicted cell voltage Vsel, and calculates the predicted terminal voltage N × V
This is the result of subtracting the actually detected terminal voltage V from sel. If no cell short circuit has occurred in each cell 1a, the subtraction result should be almost 0V. However, when a cell short-circuit has occurred, the internal resistance of the cell 1a in which the cell short-circuit has occurred is almost 0Ω, so that this partial expression (N × Vsel−V) increases in proportion to the number of short-circuit cells. Will show the value. Therefore, by dividing this sub-expression (N × Vsel−V) by the predicted cell voltage Vsel, the number of short-circuit cells, which is the number of cells 1a having a short-circuit, can be obtained. However, the number of short-circuit cells obtained by this division usually has a fraction below the decimal point. However, a cell short-circuit is a phenomenon in which the positive and negative electrode plates in the cell 1a are short-circuited, and the cell 1a is partially short-circuited. Since such a state cannot be considered, the number of short-circuit cells is also generally an integer. Therefore, in the operation of S25, the fractional part below the decimal point is rounded down using the INT function for converting the value of the argument to an integer to obtain the integer number of short-circuit cells NS.

The number of short-circuit cells detected in this way is S
26 is recorded in the EEPROM 2e. EE
The PROM 2e can store 16-bit data at each address (16-bit address). In the recording area for the number of short-circuit cells, as shown in FIG. Each short-circuit cell number up to 12 cells is allocated, and a numerical value of the number of times of detection from 0 to 65535 can be recorded at each address. The numerical value of each address is all initialized to 0 when the storage battery device is shipped from the factory. And S
In the process of 26, for example, if two cells are detected as the number of short-circuit cells, the EE corresponding to the two cells having the number of short-circuit cells
The numerical value recorded at the address on the PROM 2e is incremented and updated. Therefore, the number of short-circuit cells detected here is recorded as a histogram-like table on the EEPROM 2e. When the number of short-circuited cells recorded here is used for the determination of a battery abnormality, etc., in order to take care of the detection, the number of detected cells having the largest number of cells among the three or more times is used. The number of effective short-circuit cells is assumed. Therefore, for example, even if the number of short-circuited cells of 5 cells is detected and recorded only once or twice, if the maximum value of the number of short-circuited cells detected 3 or more times is 4 cells, the effective number of short-circuited cells is Is 4 cells.

Once charging is started, in the interrupt routine called thereafter, it is determined that the charging state has been set in the process of S2. In this case as well, subsequently, it is determined whether or not the value of the detected charging current is equal to or greater than the charging start current Imin (S9).
After executing the processing of steps 6 to S8, the interrupt routine is terminated.

The charging operation is completed when the operator removes the storage battery device from the charger or when the charger automatically detects full charge by the -ΔV charging method or the like. When the charging is completed, the charging current is not supplied. Therefore, in the processing of S9 shown in FIG. 2 in the interrupt routine called first after that, it is determined that the charging current has become less than the charging start current Imin. Is returned to the timer time T1 interval (S10), the charge state is released (S11), the value of the charge current in the RAM is updated to 0A, and the interrupt routine is terminated from (S12).
Then, the control returns from the charging state to the initial standby state. However, when the remaining capacity at the start of charging is equal to or more than R% of the rated battery capacity, or when charging is stopped before the integrated battery capacity reaches R% of the rated battery capacity, the above S8
Does not actually detect the number of short-circuit cells.

As described above, according to the apparatus for detecting the number of short-circuited cells of the storage battery device of the present embodiment, the number of short-circuited cells is determined from the difference between the terminal voltage predicted based on the predicted cell voltage and the actually detected terminal voltage. At the time of calculation, the change in cell voltage according to the magnitude of the charging current is taken into account, so that the accurate number of short-circuited cells can be detected. Thus, for example, when it is determined that the battery is abnormal when the number of short-circuit cells becomes equal to or more than a predetermined number, the reliability of the determination can be increased.

When the dry-up is detected, it is determined whether or not the cell voltage of each cell 1a of the nickel cadmium storage battery 1 is abnormally high.
The terminal voltage is divided by the value obtained by subtracting the number of short-circuit cells from the number of rated cells. Therefore, by detecting the accurate number of short-circuit cells by the short-circuit cell number detection device of the present embodiment, it is possible to make dry-up detection highly reliable.

Further, the integrated battery capacity stored in the RAM is set to, for example, a value of 0 mAm second immediately after the manufacture of the battery device in which the nickel cadmium battery 1 is in a completely discharged state. In addition to the addition, at the time of discharge, the integration process of subtracting the discharge capacity calculated by a method not described in this embodiment is repeated so that the battery capacity actually stored at that time in the nickel cadmium storage battery 1 is represented as needed. Has become.
At this time, when discharging, the nickel cadmium storage battery 1
When the cell voltage of each cell 1a becomes equal to or less than a predetermined voltage, it is determined that the battery has been completely discharged, and the integrated battery capacity is reset to a value of 0 mAm seconds to prevent accumulation of errors due to integration. Therefore, also in this case, in order to compare the cell voltage with the predetermined voltage, it is necessary to divide the terminal voltage by a value obtained by subtracting the number of short-circuit cells from the number of rated cells. By detecting the short-circuit cell number, the reset of the integrated battery capacity can be appropriately performed.

[0042]

As is clear from the above description, according to the storage battery device with the short-circuit cell number detection function of the present invention, the difference between the terminal voltage predicted based on the predicted cell voltage and the actually detected terminal voltage is obtained. When calculating the number of short-circuit cells, the change in cell voltage according to the magnitude of the charging current is taken into account, so that the accurate number of short-circuit cells can be detected.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a flow chart showing the operation of the short-circuit cell number detection processing shown in FIG.

FIG. 2, showing an embodiment of the present invention, is a flowchart illustrating the operation of an interrupt routine in a microcomputer.

FIG. 3, showing an embodiment of the present invention, is a block diagram illustrating a configuration of a storage battery device.

FIG. 4 illustrates an example of the present invention, and is a diagram illustrating a relationship between a charging current and a predicted cell voltage.

FIG. 5 shows an embodiment of the present invention, wherein an EEP
4 is a memory map of a recording area of a short-circuit cell number in a ROM.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 nickel cadmium storage battery 2 microcomputer board 2 a microcomputer 2 b terminal voltage input circuit 2 c charging current input circuit 2 e EEPROM 4 shunt resistor

Claims (2)

(57) [Claims] A chargeable storage battery comprising a plurality of cells; a charge current detection means for detecting a charge current flowing into the storage battery during charging; a terminal voltage detection means for detecting a terminal voltage of the storage battery during charging; A voltage value set in advance as an initial value for estimating the voltage, based on the charging current detected by the charging current detection unit,
The conversion is performed according to a predetermined conversion procedure in which the larger the charging current is, the higher the voltage value is.
Predicted cell voltage calculating means for calculating a cell voltage per cell as a predicted cell voltage; rated cell number recording means for recording the rated cell number of the storage battery; predicted cell voltage and rated cell calculated by the predicted cell voltage calculating means Short circuit cell number calculating means for subtracting the terminal voltage detected by the terminal voltage detecting means from a product of the rated cell number recorded in the number recording means and further dividing the subtraction result by the predicted cell voltage to obtain the number of short circuit cells. And a storage battery device with a function of detecting the number of short-circuit cells. 2. The method according to claim 1, further comprising a short-circuit cell number integer converting means for rounding off the value below the decimal point of the short-circuit cell number calculated by the short-circuit cell number calculating means to convert the short-circuit cell number into an integer. The storage battery device with the short-circuit cell number detection function described in the above.